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Sample records for gram-positive cocci isolated

  1. Gram-Positive Anaerobic Cocci

    PubMed Central

    Murdoch, D. A.

    1998-01-01

    Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum β-lactam resistance. PMID:9457430

  2. Vancomycin-Resistant Gram-Positive Cocci Isolated from the Saliva of Wild Songbirds

    PubMed Central

    Ishihara, Shingo; Bitner, Jessica J.; Farley, Greg H.

    2014-01-01

    We analyzed highly vancomycin-resistant Gram-positive bacteria isolated from the saliva of migratory songbirds captured, sampled, and released from a birdbanding station in western Kansas. Individual bacterial isolates were identified by partial 16S rRNA sequencing. Most of the bacteria in this study were shown to be Staphylococcus succinus with the majority being isolated from the American Robin. Some of these bacteria were shown to carry vanA, vanB, and vanC vancomycin-resistance genes and have the ability to form biofilms. One of the van gene-carrying isolates is also coagulase positive, which is normally considered a virulence factor. Other organisms isolated included Staphylococcus saprophyticus as well as Enterococcus gallinarum. Given the wide range of the American Robin and ease of horizontal gene transfer between Gram-positive cocci, we postulate that these organisms could serve as a reservoir of vancomycin-resistance genes capable of transferring to human pathogens. PMID:23224296

  3. Identification of lactic acid bacteria and Gram-positive catalase-positive cocci isolated from naturally fermented sausage (sucuk).

    PubMed

    Kaban, G; Kaya, M

    2008-10-01

    The aim of the study was to identify lactic acid bacteria and Gram-positive catalase-positive cocci isolated from Turkish dry fermented sausage (sucuk) produced by 7 different manufacturers without using starter culture. A total of 129 isolates of lactic acid bacteria were identified phenotypically. Lactobacillus plantarum was the dominant species (45.7%) followed by L. curvatus (10.9%) and L. fermentum (9.3%). Pediococcus isolates were identified as P. pentosaceus and P. acidilactici. All the isolates of gram-positive and catalase-positive cocci (123 isolates) were classified as Staphylococcus except for 1 isolate assigned to Kocuria rosea. The species isolated most often were S. xylosus (41.5%) and S. saprophyticus (28.5%). Four isolates were identified as S. equorum (3.3%), 1 isolate was assigned to S. carnosus (0.8%). PMID:19019118

  4. [Antimicrobial susceptibility of clinical isolates of aerobic Gram-positive cocci and anaerobic bacteria in 2006].

    PubMed

    Yamaguchi, Takahiro; Yoshida, Isamu; Itoh, Yoshihisa; Tachibana, Mineji; Takahashi, Choichiro; Kaku, Mitsuo; Kanemitsu, Keiji; Okada, Masahiko; Horikawa, Yoshinori; Shiotani, Joji; Kino, Hiroyoshi; Ono, Yuka; Baba, Hisashi; Matsuo, Shuji; Asari, Seishi; Toyokawa, Masahiro; Matsuoka, Kimiko; Kusano, Nobuchika; Nose, Motoko; Murase, Mitsuharu; Miyamoto, Hitoshi; Saikawa, Tetsunori; Hiramatsu, Kazufumi; Kohno, Shigeru; Yanagihara, Katsunori; Yamane, Nobuhisa; Nakasone, Isamu; Maki, Hideki; Yamano, Yoshinori

    2010-12-01

    The activity of antibacterial agents against aerobic Gram-positive cocci (26 species, 1022 strains) and anaerobic bacteria (23 species, 184 strains) isolated from clinical specimens in 2006 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 53.0% and 65.8%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 micrcog/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 87.6%. Ceftriaxone, cefpirome, cefepime, carbapenem antibiotics, VCM, teicoplanin, linezolid(LZD) and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 10.9% of E. faecalis strains or 3.5% of E. faecium strains showed intermediate or resistant to LZD. 24.4% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM were under 1 microg/mL, suggesting that VCM had excellent activity against C. difficile. Carbapenems showed good activity against Peptococcaceae, Bacteroides spp., and Prevotella spp. However since several strains of Bacteroides fragilis showed resistant to carbapenems and the susceptibility of this species should be well-focused in the future. PMID:21425596

  5. [Antimicrobial susceptibility of clinical isolates of aerobic gram-positive cocci and anaerobic bacteria in 2008].

    PubMed

    Yoshida, Isamu; Yamaguchi, Takahiro; Kudo, Reiko; Fuji, Rieko; Takahashi, Choichiro; Oota, Reiko; Kaku, Mitsuo; Kunishima, Hiroyuki; Okada, Masahiko; Horikawa, Yoshinori; Shiotani, Joji; Kino, Hiroyoshi; Ono, Yuka; Fujita, Shinichi; Matsuo, Shuji; Kono, Hisashi; Asari, Seishi; Toyokawa, Masahiro; Kusano, Nobuchika; Nose, Motoko; Horii, Toshinobu; Tanimoto, Ayako; Miyamoto, Hitoshi; Saikawa, Tetsunori; Hiramatsu, Kazufumi; Kohno, Shigeru; Yanagihara, Katsunori; Yamane, Nobuhisa; Nakasone, Isamu; Maki, Hideki; Yamano, Yoshinori

    2012-02-01

    The activity of antibacterial agents against aerobic Gram-positive cocci (25 genus or species, 1029 strains) and anaerobic bacteria (21 genus or species, 187 strains) isolated from clinical specimens in 2008 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 59.6% and 81.2%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM), linezolid (LZD) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 microg/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 92.0% that was highest among our previous reports. Cefpirome, carbapenems, VCM, teicoplanin (TEIC), LZD and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 15.9% of E. faecalis strains and 1.2% of E. faecium strains showed intermediate to LZD. 17.1% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM was under 1 microg/mL, suggesting that VCM had excellent activity. Carbapenems showed good activity against Clostridiales, Bacteroides spp., and Prevotella spp., but one strain of Bacteroides fragilis showed resistant to carbapenems. And so, the susceptibility of this species should be well-focused in the future at detecting continuously. PMID:22808693

  6. Numerical taxonomy of moderately halophilic gram-positive cocci isolated from the Salar de Atacama (Chile).

    PubMed

    Valderrama, M J; Prado, B; del Moral, A; Ríos, R; Ramos-Cormenzana, A; Campos, V

    1991-06-01

    A taxonomic study has been carried out on 22 strains of moderately halophilic motile cocci isolated from the Salar de Atacama (Chile). The 112 phenotypic tests were analyzed by numerical taxonomy using SSM coefficient and the unweighted pair group method of association (UPGMA). At the 67% similarity level, two phenons were obtained: phenon A included 11 strains and phenon B, 11 strains too, whereas the six reference strains did not cluster within these two phenons. These results suggest that moderately halophilic cocci with different phenotypic characteristics from previously described species can be isolated from the hypersaline habitat Salar de Atacama. PMID:1867776

  7. Changes of the Quinolones Resistance to Gram-positive Cocci Isolated during the Past 8 Years in the First Bethune Hospital

    NASA Astrophysics Data System (ADS)

    Xu, Jiancheng; Chen, Qihui; Yao, Hanxin; Zhou, Qi

    This study was to investigate the quinolones resistance to gram-positive cocci isolated in the First Bethune Hospital during the past 8 years. Disk diffusion test was used to study the antimicrobial resistance. The data were analyzed by WHONET 5 software according to Clinical and Laboratory Standards Institute (CLSI). The rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococci (MRCNS) were 50.8%∼83.3% and 79.4%∼81.5%during the past 8 years, respectively. In recent 8 years, the quinolones resistance to gram-positive cocci had increased. Monitoring of the quinolones resistance to gram-positive cocci should be strengthened. The change of the antimicrobial resistance should be investigated in order to guide rational drug usage in the clinic and prevent bacterial strain of drug resistance from being transmitted.

  8. Vancomycin tolerance in Gram-positive cocci.

    PubMed

    Moscoso, Miriam; Domenech, Mirian; García, Ernesto

    2011-12-01

    Vancomycin, a glycopeptide antimicrobial agent, represents the last line of defence against a wide range of multi-resistant Gram-positive pathogens such as enterococci, staphylococci and streptococci. However, vancomycin-resistant enterococci and staphylococci, along with vancomycin-tolerant clinical isolates, are compromising the therapeutic efficacy of vancomycin. It is conceivable that tolerance may emerge during prolonged vancomycin use. It has not been until recently, however, that the molecular basis of this tolerance began to be understood. Superoxide anions might be involved in the bactericidal activity of vancomycin in enterococci, and recent evidence suggests that the stringent response is partly responsible for vancomycin tolerance in Enterococcus faecalis. The mechanism of vancomycin tolerance in Staphylococcus aureus and Streptococcus pneumoniae is sometimes associated with a reduction of autolysin activity. Vancomycin tolerance in S. aureus and S. pneumoniae also appears to be somehow related with the two-component regulatory systems linked to cell envelope stress, although the precise molecular regulatory pathways remain poorly defined. PMID:23761352

  9. Spectrum and potency of dalbavancin tested against 3322 Gram-positive cocci isolated in the United States Surveillance Program (2004).

    PubMed

    Jones, Ronald N; Stilwell, Matthew G; Sader, Helio S; Fritsche, Thomas R; Goldstein, Beth P

    2006-02-01

    Dalbavancin is an injectable, next generation lipoglycopeptide with an extended serum elimination half-life. Once-weekly dosing has been successful for treatment of skin and skin structure (SSSI) and catheter-related bloodstream infections (CR-BSI). Concurrent with clinical trails, dalbavancin resistance surveillance was initiated in 2003, and results are reported here for the 2004 United States (USA) component. A total of 3322 Gram-positive cocci were tested by reference broth microdilution methods. Organism species tested included: Staphylococcus aureus (2102; 49% oxacillin-resistant), coagulase-negative staphylococci (CoNS; 255, 82% oxacillin-resistant), beta-hemolytic streptococci (241), viridans group streptococci (46), and Streptococcus pneumoniae (678). Dalbavancin (MIC90,0.06-0.12 microg/mL) was comparable in spectrum, but superior in potency to vancomycin (MIC90,1-2 microg/mL) against staphylococci. Dalbavancin MIC90 values against the tested streptococci was 0.03 microg/mL. Dalbavancin was more active against tested SSTI pathogens than comparator agents having complete susceptibility rates (100.0%) similar to vancomycin. Vancomycin, (16- to 32-fold), linezolid (8- to 32-fold), daptomycin (4- to 32-fold), and quinupristin/dalfopristin (4- to 32-fold) were less active than dalbavancin. In conclusion, dalbavancin exhibited greater potency than comparison glycopeptides or lipopeptides, streptogramin combinations, and oxazolidinones against Gram-positive pathogens associated with SSSI or CR-BSI. Dalbavancin wild-type MIC distributions remain unchanged compared with prior sampled years (2002-2003) in the USA. PMID:16426793

  10. Glycopeptide Resistance in Gram-Positive Cocci: A Review

    PubMed Central

    Sujatha, S.; Praharaj, Ira

    2012-01-01

    Vancomycin-resistant enterococci (VRE) have emerged as important nosocomial pathogens in the past two decades all over the world and have seriously limited the choices available to clinicians for treating infections caused by these agents. Methicillin-resistant Staphylococcus aureus, perhaps the most notorious among the nosocomial pathogens, was till recently susceptible to vancomycin and the other glycopeptides. Emergence of vancomycin nonsusceptible strains of S. aureus has led to a worrisome scenario where the options available for treating serious infections due to these organisms are very limited and not well evaluated. Vancomycin resistance in clinically significant isolates of coagulase-negative staphylococci is also on the rise in many setups. This paper aims to highlight the genetic basis of vancomycin resistance in Enterococcus species and S. aureus. It also focuses on important considerations in detection of vancomycin resistance in these gram-positive bacteria. The problem of glycopeptide resistance in clinical isolates of coagulase-negative staphylococci and the phenomenon of vancomycin tolerance seen in some strains of Streptococcus pneumoniae has also been discussed. Finally, therapeutic options available and being developed against these pathogens have also found a mention. PMID:22778729

  11. New antimicrobial agents as therapy for resistant gram-positive cocci.

    PubMed

    Lentino, J R; Narita, M; Yu, V L

    2008-01-01

    Vancomycin- and methicillin-resistant gram-positive cocci have emerged as an increasingly problematic cause of hospital-acquired infections. We conducted a literature review of newer antibiotics with activity against vancomycin-resistant and methicillin-resistant gram-positive cocci. Quinupristin/dalfopristin, linezolid, daptomycin, and tigecycline have in vitro activity for methicillin-resistant staphylococci and are superior to vancomycin for vancomycin-resistant isolates. Dalbavancin, telavancin, and oritavancin are new glycopeptides that have superior pharmacodynamic properties compared to vancomycin. We review the antibacterial spectrum, clinical indications and contraindications, pharmacologic properties, and adverse events associated with each of these agents. Daptomycin has rapid bactericidal activity for Staphylococcus aureus and is approved for use in bacteremia and right-sided endocarditis. Linezolid is comparable to vancomycin in patients with methicillin-resistant S. aureus (MRSA) pneumonia and has pharmacoeconomic advantages given its oral formulation. Quinupristin/dalfopristin is the drug of choice for vancomycin-resistant Enterococcus faecium infections but has no activity against Enterococcus faecalis. Tigecycline has activity against both enterococcus species and MRSA; it is also active against Enterobacteriaceae and anaerobes which allows for use in intra-abdominal and diabetic foot infections. A review of numerous in vitro and animal model studies shows that interaction between these newer agents and other antistaphylococcal agents for S. aureus are usually indifferent (additive). PMID:17899228

  12. Activity of quinolones against gram-positive cocci: clinical features.

    PubMed

    Giamarellou, H

    1995-01-01

    The potential role of the commercially available fluoroquinolones in the treatment of Gram-positive infections is discussed on the basis of data obtained from animal experiments and clinical trials. In respiratory tract infections, and particularly in community-acquired pneumonia, it is evident that the presently available quinolones cannot be prescribed empirically as first-line therapy because of their borderline activity against Streptococcus pneumoniae and anaerobes. Reports of pneumococcal seeding in other tissues during quinolone therapy render their administration a debatable issue. Experience in endocarditis is limited to the use of ciprofloxacin plus rifampicin in intravenous drug users with right-sided Staphylococcus aureus endocarditis. Patients with staphylococcal osteomyelitis are included among cases of other bone infections. In noncontrolled studies ciprofloxacin, ofloxacin and pefloxacin attained a staphylococcal eradication rate ranging from 70 to 100%, while the addition of rifampicin has been proven to reduce the emergence of resistant mutants during therapy. In soft tissue and skin structure infections that also involve Gram-negative bacteria, ciprofloxacin and ofloxacin eradicated 72.6 and 89% of staphylococci, respectively; however, the presence of diabetes or vascular disease compromised the success of treatment. In staphylococcal peritonitis complicating continuous ambulatory peritoneal dialysis, results with ciprofloxacin given intravenously or intraperitoneally were promising. In infections in neutropenic hosts, success of prophylaxis or therapy is still not clear, since colonisation and breakthrough bacteraemias with viridans streptococci and staphylococci have been reported. Furthermore, therapeutic results are compromised by the low response rate in Gram-positive infections. Despite the reported clinical efficacy of the newer fluoroquinolones, physicians should be alerted to the emergence of staphylococci resistant to fluoroquinolones

  13. Antibiotic therapeutic options for infections caused by drug-resistant Gram-positive cocci.

    PubMed

    Banwan, K; Senok, A C; Rotimi, V O

    2009-01-01

    Serious infections caused by Gram-positive bacteria are currently difficult to treat because many of these pathogens are now resistant to standard antimicrobial agents. As a result of the emergence and spread of multidrug-resistant Gram-positive pathogens, new antimicrobial agents are urgently needed for clinical use. In recent years, there has been an increase in the number of drugs that have activity against these Gram-positive pathogens. Daptomycin, tigecycline, linezolid, quinupristin/dalfopristin and dalbavancin are five antimicrobial agents that are useful for the treatment of infections due to drug-resistant Gram-positive cocci. This review focuses on their mechanism of action, pharmacokinetics, spectrum of activity, clinical effectiveness, drug interaction and safety. These antimicrobial agents provide the clinician with additional treatment options among the limited therapies for resistant Gram-positive bacterial infection. PMID:20701863

  14. Development of a five-hour radiometric serum antibacterial assay for gram-positive cocci

    SciTech Connect

    Beckwith, D.G.; Guidon, P.T. Jr.

    1981-03-01

    A preliminary report on a 5-hr radiometric serum antibacterial assay (ABA) for Gram-positive cocci is presented. The method agreed within +- one twofold dilution with static ABA endpoints in 24/26 (92%) of the assays and with cidal ABA end-points in 23/26 (88%) of the assays performed.

  15. Identification, classification, and clinical relevance of catalase-negative, gram-positive cocci, excluding the streptococci and enterococci.

    PubMed Central

    Facklam, R; Elliott, J A

    1995-01-01

    Several new genera and species of gram-positive, catalase-negative cocci that can cause infections in humans have been described. Although these bacteria were isolated in the clinical laboratory, they were considered nonpathogenic culture contaminants and were not thought to be the cause of any diseases. Isolation of pure cultures of these bacteria from normally sterile sites has led to the conclusion that these bacteria can be an infrequent cause of infection. This review describes the new bacteria and the procedures useful for clinical laboratories to aid in their identification. The clinical relevance and our experience with the various genera and species are reviewed and discussed. PMID:8665466

  16. Molecular, technological and safety characterization of Gram-positive catalase-positive cocci from slightly fermented sausages.

    PubMed

    Martín, B; Garriga, M; Hugas, M; Bover-Cid, S; Veciana-Nogués, M T; Aymerich, T

    2006-03-15

    The population of Gram-positive catalase-positive cocci from slightly fermented sausages was characterized at species and strain level by molecular techniques and some technological and hygienic aspects were also considered. Staphylococcus xylosus was the predominant species (80.8%) followed by Staphylococcus warneri (8.3%), Staphylococcus epidermidis (5.8%) Staphylococcus carnosus (4.6%), and Kocuria varians (0.4%). Proteolytic activity was observed in 23% of the isolates. The species with the highest percentage of proteolytic strains was S. warneri. Lipolytic activity was found in 45.8% of the isolates and S. xylosus was the species with the highest percentage of lipolytic isolates. Biogenic amine production was not widely distributed (only 14.6% of the isolates). Tyramine was the most intense amine produced, although by only 4.6% of the isolates. Phenylethylamine was more frequently detected (10.8% of isolates) but at lower levels. Some strains also produced putrescine (3.3%), cadaverine (2.9%), histamine (1.3%) and tryptamine (0.4%). All isolates were susceptible to linezolid and vancomicin and over 70% were resistant to penicillin G, ampicillin and sulphonamides. Most of the mecA+ strains (only 4.6% of isolates) also displayed resistance to multiple antibiotics. A reduced enterotoxigenic potential was found. Only 3.3% of isolates showed staphylococcal enterotoxins genes, all identified as entC gene. The combination of RAPD-PCR and plasmid profiling allowed the discrimination of 208 different profiles among the 240 Gram-positive catalase-positive cocci characterized, indicating a great genetic variability. PMID:16297478

  17. Evaluation of the automated system Vitek2 for identification and antimicrobial susceptibility testing of Brazilian Gram-positive cocci strains.

    PubMed

    d'Azevedo, Pedro Alves; Siquiera, Itacy; Gugel, Juliana; Antunes, Ana Lúcia Souza; Secchi, Carina; Pasternak, Jacyr; Martino, Marinês Dalla Vale

    2009-04-01

    Automated instruments offer many advantages for clinical laboratories. Nevertheless, they can have problems identifying and determining susceptibilities of some pathogens. Vitek2 (bioMérieux) is an automated system that was recently introduced to Brazil. We evaluated the performance of this equipment for Brazilian isolates that had been characterized using reference identification and antimicrobial susceptibility testing methods. Ninety-nine strains of Gram-positive cocci from a local reference center collection were analyzed, consisting of 50 coagulase-negative Staphylococcus (CoNS) and 49 Enterococcus and related species. Vitek2 correctly identified 79.8% (79/99) of the isolates. Oxacillin resistance was detected in 76% (19/25) of resistant S. epidermidis strains and in 88% (22/25) of other resistant CoNS species strains. Vancomycin resistance was detected in 100% (20/20) of resistant Enterococcus and related species strains. Vitek2 performed very well for the identification of S. epidermidis and non-epidermidis staphylococci, and for the detection of vancomycin resistance in Enterococcus and related species. However, the system needs improvement in order to provide reliable results for the characterization of some CoNS species, identification of Enterococcus and related species and for detecting oxacillin resistance in CoNS. PMID:20140353

  18. Accuracy of the VITEK® 2 system for a rapid and direct identification and susceptibility testing of Gramnegative rods and Gram-positive cocci in blood samples.

    PubMed

    Nimer, N A; Al-Saa'da, R J; Abuelaish, O

    2016-03-01

    The performance of the VITEK® 2 system for direct rapid identification and antimicrobial susceptibility testing of the bacteria responsible for blood infections was determined. The isolates studied included 166 Gram-negative rods and 74 Gram-positive cocci from inpatients. Specially treated monomicrobial samples from positive blood culture bottles were directly inoculated into the VITEK 2 system and the results were compared with those from cards inoculated with standardized bacterial suspensions. Compared with the standard method, 95.8% of Gram-negative rods were correctly identified by VITEK 2 and the overall level of agreement between the two methods in susceptibility testing was 92.0%. For Gram-positive bacteria, 89.2% were correctly identified by VITEK 2 and susceptibility testing revealed an overall agreement rate of 91.3%. These results suggest that VITEK 2 cards inoculated with fluids sampled directly from positive blood culture bottles are suitable for speedy identification and susceptibility testing of Gram-negative bacilli and Gram-positive cocci. PMID:27334076

  19. [Resistance to "last resort" antibiotics in Gram-positive cocci: The post-vancomycin era].

    PubMed

    Rincón, Sandra; Panesso, Diana; Díaz, Lorena; Carvajal, Lina P; Reyes, Jinnethe; Munita, José M; Arias, César A

    2014-04-01

    New therapeutic alternatives have been developed in the last years for the treatment of multidrug-resistant Gram-positive infections. Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are considered a therapeutic challenge due to failures and lack of reliable antimicrobial options. Despite concerns related to the use of vancomycin in the treatment of severe MRSA infections in specific clinical scenarios, there is a paucity of solid clinical evidence that support the use of alternative agents (when compared to vancomycin). Linezolid, daptomycin and tigecycline are antibiotics approved in the last decade and newer cephalosporins (such as ceftaroline and ceftobiprole) and novel glycopeptides (dalvavancin, telavancin and oritavancin) have reached clinical approval or are in the late stages of clinical development. This review focuses on discussing these newer antibiotics used in the "post-vancomycin" era with emphasis on relevant chemical characteristics, spectrum of antimicrobial activity, mechanisms of action and resistance, as well as their clinical utility. PMID:24968051

  20. 18 GHz electromagnetic field induces permeability of Gram-positive cocci

    PubMed Central

    Nguyen, The Hong Phong; Shamis, Yury; Croft, Rodney J.; Wood, Andrew; McIntosh, Robert L.; Crawford, Russell J.; Ivanova, Elena P.

    2015-01-01

    The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8T, S. aureus ATCC 25923 and S. epidermidis ATCC 14990T, was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains (S. epidermidis ATCC 14990T~ 0%; Staphylococcus aureus CIP 65.8T S. aureus ATCC 25923, ~40%; Planococcus maritimus KMM 3738, ~80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy. PMID:26077933

  1. Use of Enzyme Tests in Characterization and Identification of Aerobic and Facultatively Anaerobic Gram-Positive Cocci

    PubMed Central

    Bascomb, Shoshana; Manafi, Mammad

    1998-01-01

    The contribution of enzyme tests to the accurate and rapid routine identification of gram-positive cocci is introduced. The current taxonomy of the genera of aerobic and facultatively anaerobic cocci based on genotypic and phenotypic characterization is reviewed. The clinical and economic importance of members of these taxa is briefly summarized. Tables summarizing test schemes and kits available for the identification of staphylococci, enterococci, and streptococci on the basis of general requirements, number of tests, number of taxa, test classes, and completion times are discussed. Enzyme tests included in each scheme are compared on the basis of their synthetic moiety. The current understanding of the activity of enzymes important for classification and identification of the major groups, methods of testing, and relevance to the ease and speed of identification are reviewed. Publications describing the use of different identification kits are listed, and overall identification successes and problems are discussed. The relationships between the results of conventional biochemical and rapid enzyme tests are described and considered. The use of synthetic substrates for the detection of glycosidases and peptidases is reviewed, and the advantages of fluorogenic synthetic moieties are discussed. The relevance of enzyme tests to accurate and meaningful rapid routine identification is discussed. PMID:9564566

  2. Evaluation of the in vitro activity of tigecycline against multiresistant Gram-positive cocci containing tetracycline resistance determinants.

    PubMed

    Borbone, Sonia; Lupo, Agnese; Mezzatesta, Maria Lina; Campanile, Floriana; Santagati, Maria; Stefani, Stefania

    2008-03-01

    This study was undertaken to test the in vitro activity of tigecycline against 117 clinically relevant Gram-positive pathogens and to correlate this activity with their resistance gene content. Overall, tigecycline showed a minimal inhibitory concentration (MIC) range of 0.015-0.5mg/L, able to inhibit potently all multiresistant streptococci, enterococci and MR staphylococci. Tigecycline was active against methicillin-resistant Staphylococcus aureus (MRSA) and enterococci, with MICs for 90% of the organisms (MIC(90)) of 0.25 mg/L and 0.12 mg/L, respectively, being more active than linezolid (MIC(90)=2 mg/L) and quinupristin/dalfopristin (MIC(90)=0.5 and 2-4 mg/L, respectively). Molecular characterisation of resistance determinants demonstrated the concomitant presence of different classes of genes: in particular, tet(M), erm(B) and erm(C) in Streptococcus agalactiae; tet(O), variably associated with different erm genes, in Streptococcus pyogenes; vanA, tet(M) and erm(B) in Enterococcus faecalis, and vanA and erm(B) in Enterococcus faecium. All the MRSA strains harboured SCCmec and erm genes and 50% possessed tet(K) with tet(M) genes. Staphylococcus epidermidis strains were only resistant to erythromycin. These results clearly demonstrate that tigecycline has a MIC(90) range of 0.015-0.5 mg/L both against tetracycline-susceptible and -resistant isolates carrying other resistance determinants, suggesting that this drug could play an important role in the treatment of infections caused by these multiresistant Gram-positive pathogens. PMID:17646087

  3. Survey of Extreme Solvent Tolerance in Gram-Positive Cocci: Membrane Fatty Acid Changes in Staphylococcus haemolyticus Grown in Toluene

    PubMed Central

    Nielsen, Lindsey E.; Kadavy, Dana R.; Rajagopal, Soumitra; Drijber, Rhae; Nickerson, Kenneth W.

    2005-01-01

    We exploited the unique ecological niche of oil fly larval guts to isolate a strain of Staphylococcus haemolyticus which may be the most solvent-tolerant gram-positive bacterium yet described. This organism is able to tolerate 100% toluene, benzene, and p-xylene on plate overlays and saturating levels of these solvents in monophasic liquid cultures. A comparison of membrane fatty acids by gas chromatography after growth in liquid media with and without toluene showed that in cells continuously exposed to solvent the proportion of anteiso fatty acids increased from 25.8 to 33.7% while the proportion of 20:0 straight-chain fatty acids decreased from 19.3 to 10.1%. No changes in the membrane phospholipid composition were noted. Thus, S. haemolyticus alters its membrane fluidity via fatty acid composition to become more fluid when it is exposed to solvent. This response is opposite that commonly found in gram-negative bacteria, which change their fatty acids so that the cytoplasmic membrane is less fluid. Extreme solvent tolerance in S. haemolyticus is not accompanied by abnormal resistance to anionic or cationic detergents. Finally, six strains of Staphylococcus aureus and five strains of Staphylococcus epidermidis, which were not obtained by solvent selection, also exhibited exceptional solvent tolerance. PMID:16151101

  4. Novel physico-chemical diagnostic tools for high throughput identification of bovine mastitis associated gram-positive, catalase-negative cocci

    PubMed Central

    2014-01-01

    Background The routine diagnosis of Streptococcus spp. and other mastitis associated gram-positive, catalase-negative cocci is still based upon biochemical tests and serological methods, which frequently provide ambiguous identification results. We therefore aimed to establish an accurate identification system for differential diagnosis of mastitis associated Streptococcus spp. and related species using biophysical techniques such as Fourier-transform infrared (FTIR) spectroscopy and MALDI – TOF/MS. Results Based on a panel of 210 isolates from cases of bovine mastitis, an unsupervised FTIR spectral reference library was established and an artificial neural network (ANN) - assisted identification system was developed. All bacterial isolates were previously identified by species-specific PCR and/or 16S rRNA gene sequence analysis. An overall identification rate of 100% at species level for 173 strains unknown to the ANN and the library was achieved by combining ANN and the spectral database, thus demonstrating the suitability of our FTIR identification system for routine diagnosis. In addition, we investigated the potential of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of mastitis associated Streptococcus spp. and related bacteria. Using the Microflex LT System, MALDI Biotyper software™ (V3.3) we achieved an accuracy rate of 95.2%. A blind study, including 21 clinical samples from dairy cows, revealed a 100% correct species identification rate for FTIR and 90.5% for MALDI-TOF MS, indicating that these techniques are valuable tools for diagnosis. Conclusions This study clearly demonstrates that FTIR spectroscopy as well as MALDI-TOF MS can significantly improve and facilitate the identification and differentiation of mastitis associated Streptococcus spp. and related species. Although the FTIR identification system turned out being slightly superior to MALDI-TOF MS in terms of identification

  5. Unusual coiled gram-positive anaerobe isolated from a gutter wall abscess.

    PubMed Central

    Pollock, H M; Rintala, L

    1977-01-01

    A gram-positive, nonsporing coiled rod was visible on Gram stain and isolated in pure culture from 20 ml of pus. This organism differs from previously described species in that it produces only acetic acid from glucose metabolism, hydrolyzes esculin, and has less fermentative activity in carbohydrates. Images PMID:145446

  6. Comparison of Direct Colony Method versus Extraction Method for Identification of Gram-Positive Cocci by Use of Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry ▿

    PubMed Central

    Alatoom, Adnan A.; Cunningham, Scott A.; Ihde, Sherry M.; Mandrekar, Jayawant; Patel, Robin

    2011-01-01

    We evaluated Bruker Biotyper (version 2.0) matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) for the identification of 305 clinical isolates of staphylococci, streptococci, and related genera by comparing direct colony testing with preparatory extraction. Isolates were previously identified by use of phenotypic testing and/or 16S rRNA gene sequencing. Manufacturer-specified score cutoffs for genus- and species-level identification were used. After excluding 7 isolates not present in the Biotyper library, the Biotyper correctly identified 284 (95%) and 207 (69%) isolates to the genus and species levels, respectively, using extraction. By using direct colony testing, the Biotyper identified 168 (56%) and 60 (20%) isolates to the genus and species levels, respectively. Overall, more isolates were identified to the genus and species levels with preparatory extraction than with direct colony testing (P < 0.0001). The analysis was repeated after dividing the isolates into two subgroups, staphylococci, streptococci, and enterococci (n = 217) and “related genera” (n = 81). For the former subgroup, the extraction method resulted in the identification of 213 (98%) and 171 (79%) isolates to the genus and species levels, respectively, whereas the direct colony method identified 136 (63%) and 56 (26%) isolates to the genus and species levels, respectively. In contrast, for the subgroup of related genera, the extraction method identified 71 (88%) and 36 (44%) isolates to the genus and species levels, respectively, while the direct colony method identified 32 (40%) and 4 (5%) isolates to the genus and species levels, respectively. For both subgroups, preparatory extraction was superior to direct colony testing for the identification of isolates to the genus and species levels (P < 0.0001). Preparatory extraction is needed for the identification of a substantial proportion of Gram-positive cocci using the Biotyper method according

  7. Metabolic versatility of Gram-positive microbial isolates from contaminated river sediments.

    PubMed

    Narancic, Tanja; Djokic, Lidija; Kenny, Shane T; O'Connor, Kevin E; Radulovic, Vanja; Nikodinovic-Runic, Jasmina; Vasiljevic, Branka

    2012-05-15

    Gram-positive bacteria from river sediments affected by the proximity of a petrochemical industrial site were isolated and characterized with respect to their ability to degrade a wide range of aromatic compounds. In this study we identified metabolically diverse Gram-positive bacteria capable of growth on wide range aromatic compounds in the presence of heavy metals and with the ability to accumulate biopolymers. Thirty-four isolates that were able to use 9 or more common aromatic pollutants, such as benzene, biphenyl, naphthalene etc. as a sole source of carbon and energy included members of Bacillus, Arthrobacter, Rhodococcus, Gordonia, Streptomyces, and Staphylococcus genus. Rhodococcus sp. TN105, Gordonia sp. TN103 and Arthrobacter sp. TN221 were identified as novel strains. Nine isolates were able to grow in the presence of one or more metals (mercury, cadmium, nickel) at high concentration (100mM). Seven isolates could degrade 15 different aromatic compounds and could grow in the presence of one or more heavy metals. Two of these isolates were resistant to multiple antibiotics including erythromycin and nalidixic acid. One third of isolates could accumulate at least one biopolymer. Twelve isolates (mainly Bacillus sp. and Arthrobacter sp.) accumulated polyphosphate, 3 Bacillus sp. accumulated polyhydroxybutyrate, while 4 isolates could accumulate exopolysaccharides. PMID:22421345

  8. Isolation of Highly Active Monoclonal Antibodies against Multiresistant Gram-Positive Bacteria

    PubMed Central

    Rossmann, Friederike S.; Laverde, Diana; Kropec, Andrea; Romero-Saavedra, Felipe; Meyer-Buehn, Melanie; Huebner, Johannes

    2015-01-01

    Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL) of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA). At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium), a mouse peritonitis model (using S. aureus Newman and LAC) and a rat endocarditis model (using E. faecalis 12030) and were shown to provide protection in all models at a concentration of 4 μg/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials. PMID:25706415

  9. Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments

    SciTech Connect

    Van Nostrand, J. D.; Khijniak, T. V.; Gentry, T. J.; Novak, M. T.; Sowder, A. G.; Zhou, J. Z.; Bertsch, P. M.; Morris, P. J.

    2007-01-01

    Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms. Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing gene probes for functions associated with biogeochemical cycling, metal homeostasis, and organic contaminant degradation showed little overlap among the four isolates. Fifteen of the genes were detected in all four isolates with only two of these related to metal resistance, specifically to tellurium. Each of the four isolates also displayed resistance to at least one of six antibiotics tested, with resistance to kanamycin, gentamycin, and ciprofloxacin observed in at least two of the isolates. Further characterization of S. aureofaciens NR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Ni tolerance constitutively. In addition, both were able to grow in higher concentrations of Ni at pH 6 as compared with pH 7 (42.6 and 8.5 mM Ni at pH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examined in these two isolates; a similar pH-dependent metal tolerance was observed when grown with Co and Zn. Neither isolate was tolerant to Cd. These findings suggest that Ni is exerting a selection pressure at this site for metal-resistant actinomycetes.

  10. Isolating "Unknown" Bacteria in the Introductory Microbiology Laboratory: A New Selective Medium for Gram-Positives.

    ERIC Educational Resources Information Center

    McKillip, John L.; Drake, MaryAnne

    1999-01-01

    Describes the development, preparation, and use of a medium that can select against a wide variety of Gram-negative bacteria while still allowing growth and differentiation of a wide range of Gram-positives. (WRM)

  11. In Vitro Activities of the Ketolide HMR 3647 against Recent Gram-Positive Clinical Isolates and Haemophilus influenzae

    PubMed Central

    Barry, Arthur L.; Fuchs, Peter C.; Brown, Steven D.

    1998-01-01

    The ketolide HMR 3647 (previously RU 66647) was evaluated against 2,563 recent clinical isolates of gram-positive pathogens and 200 Haemophilus influenzae isolates. HMR 3647 was active against macrolide-resistant streptococci, including pneumococci, but was not active against macrolide- or lincosamide-resistant staphylococci. Against H. influenzae, the potency of HMR 3647 was similar to that of azithromycin. PMID:9687424

  12. Isolation and Characterization of Gram-Positive Piezophilic Bacteria from Deep Marine Subsurface Sediment

    NASA Astrophysics Data System (ADS)

    Runko, G. M.; Fang, J.; Kato, C.

    2014-12-01

    The marine deep biosphere remains as the least studied of all of Earth's habitats and is inadequately understood, but is extremely important to understand the impacts that microbes have on global biogeochemical cycles. Sediment samples were obtained during IODP Expedition 337 in the western Pacific Ocean, from 1,498 meters below the seafloor (mbsf; samples 6R3), 1,951-1,999 mbsf (19R1), and 2,406 mbsf (29R7). These samples were initially mixed with marine broth and cultivated under anaerobic conditions at pressure of 35 MPa (megapascal) and temperatures of 35° C, 45° C, and 55° C for 3 months on board the Chikyu. Single colonies were isolated via plating on marine broth. Then, six strains of bacteria were identified, 6R3-1, 6R3-15, 19R1-5, 29R7-12B, 29R7-12M, and 29R7-12S. The six strains were then examined for optimal growth temperature and pressure. These organisms are Gram-positive, spore-forming, facultative anaerobic piezophilic bacteria. Major fatty acids are anteiso-15:0, anteiso-17:0 and iso-15:0. Phylogenetic analysis of 16S rRNA gene sequences revealed that the isolates are closely related to Virgibacillus pantothenticus, Robinsoniella peoriensis, and Bacillus subtilis. Because of their abundance in the deep marine subsurface, these microorganisms likely play an important role in sustaining the deep microbial ecosystem and influencing biogeochemical cycles in the deep biosphere.

  13. Isolation of gram-positive rods that resemble but are clearly distinct from Actinomyces pyogenes from mixed wound infections.

    PubMed Central

    Wüst, J; Lucchini, G M; Lüthy-Hottenstein, J; Brun, F; Altwegg, M

    1993-01-01

    Beginning in 1990, gram-positive rods resembling Actinomyces pyogenes were found with increasing frequency in mixed cultures from various infectious processes, most of them from patients with otitis, empyema, pilonidal cysts, perianal abscesses, and decubitus ulcers. Ribotyping and hybridization showed that these gram-positive rods could be divided into five groups not related to known Actinomyces species. Biochemical markers for reliable differentiation into these groups, however, could not be found. Therefore, naming new species is not warranted unless parameters are discovered that allow identification without DNA hybridization. These gram-positive rods have been isolated only in mixed cultures with anaerobes, Staphylococcus aureus, Streptococcus "milleri," enterococci, and gram-negative rods. Their exact role in these possibly synergistic infections needs further investigation. Images PMID:8501213

  14. Isolation and Characterization of Gram-Positive Biosurfactant-Producing Halothermophilic Bacilli From Iranian Petroleum Reservoirs

    PubMed Central

    Zargari, Saeed; Ramezani, Amin; Ostvar, Sassan; Rezaei, Rasool; Niazi, Ali; Ayatollahi, Shahab

    2014-01-01

    Background: Petroleum reservoirs have long been known as the hosts of extremophilic microorganisms. Some of these microorganisms are known for their potential biotechnological applications, particularly production of extra and intracellular polymers and enzymes. Objectives: Here, 14 petroleum liquid samples from southern Iranian oil reservoirs were screened for presence of biosurfactant‐producing halothermophiles. Materials and Methods: Mixture of the reservoir fluid samples with a minimal growth medium was incubated under an N2 atmosphere in 40°C; 0.5 mL samples were transferred from the aqueous phase to agar plates after 72 hours of incubation; 100 mL cell cultures were prepared using the MSS-1 (mineral salt solution 1) liquid medium with 5% (w/v) NaCl. The time-course samples were analyzed by recording the absorbance at 600 nm using a spectrophotometer. Incubation was carried out in 40°C with mild shaking in aerobic conditions. Thermotolerance was evaluated by growing the isolates at 40, 50, 60 and 70°C with varying NaCl concentrations of 5% and 10% (w/v). Halotolerance was evaluated using NaCl concentrations of 5%, 10%, 12.5% and 15% (w/v) and incubating them at 40°C under aerobic and anaerobic conditions. Different phenotypic characteristics were evaluated, as outlined in Bergey's manual of determinative bacteriology. Comparing 16S rDNA sequences is one of the most powerful tools for classification of microorganisms. Results: Among 34 isolates, 10 demonstrated biosurfactant production and growth at temperatures between 40°C and 70°C in saline media containing 5%‐15% w/v NaCl. Using partial 16S rDNA sequencing (and amplified ribosomal DNA restriction analysis [ARDRA]) and biochemical tests (API tests 20E and 50 CHB), all the 10 isolates proved to be facultative anaerobic, Gram-positive moderate thermohalophiles of the genus Bacillus (B. thermoglucosidasius, B. thermodenitrificans, B. thermoleovorans, B. stearothermophilus and B. licheniformis

  15. Isolation and solubilization of gram-positive bacterial cell wall-associated proteins.

    PubMed

    Cole, Jason N; Djordjevic, Steven P; Walker, Mark J

    2008-01-01

    This chapter describes a simple, rapid and reproducible method to prepare bacterial cell wall extracts for two-dimensional gel electrophoresis (2DE). The extraction process uses mutanolysin, an N-acetylmuramidase, to gently solubilize cell wall-associated proteins from Gram-positive prokaryotes. The cells are first washed with buffer and resuspended in a solution containing mutanolysin. Following incubation at 37 degrees C, the sample is centrifuged and the supernatant containing the soluble cell wall-associated proteins is harvested. Following a brief precipitation step, the pellet is solubilized in sample buffer ready for isoelectric focusing and 2DE analysis. PMID:18369905

  16. In Vitro Activities of a New Lipopeptide, HMR 1043, against Susceptible and Resistant Gram-Positive Isolates

    PubMed Central

    Bemer, Pascale; Juvin, Marie-Emmanuelle; Bryskier, Andre; Drugeon, Henri

    2003-01-01

    The purpose of this study was to compare the activity of HMR 1043 with those of daptomycin and teicoplanin against gram-positive isolates. Susceptibility tests were performed for 52 strains, 26 parental strains, including staphylococcal, streptococcal, enterococcal, and listerial strains, and 26 HMR 1043-resistant mutants obtained from parental strains by using the Szybalski method. Agar dilution and disk diffusion susceptibility tests were performed by the procedures outlined by the NCCLS. HMR 1043 demonstrated good activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro was less influenced by the presence of calcium ions than that of daptomycin. Susceptibility test breakpoints were not defined because of the poor correlation coefficients obtained with the different disks tested. PMID:12937020

  17. Evidence for Direct Electron Transfer by a Gram-Positive Bacterium Isolated from a Microbial Fuel Cell▿†

    PubMed Central

    Wrighton, K. C.; Thrash, J. C.; Melnyk, R. A.; Bigi, J. P.; Byrne-Bailey, K. G.; Remis, J. P.; Schichnes, D.; Auer, M.; Chang, C. J.; Coates, J. D.

    2011-01-01

    Despite their importance in iron redox cycles and bioenergy production, the underlying physiological, genetic, and biochemical mechanisms of extracellular electron transfer by Gram-positive bacteria remain insufficiently understood. In this work, we investigated respiration by Thermincola potens strain JR, a Gram-positive isolate obtained from the anode surface of a microbial fuel cell, using insoluble electron acceptors. We found no evidence that soluble redox-active components were secreted into the surrounding medium on the basis of physiological experiments and cyclic voltammetry measurements. Confocal microscopy revealed highly stratified biofilms in which cells contacting the electrode surface were disproportionately viable relative to the rest of the biofilm. Furthermore, there was no correlation between biofilm thickness and power production, suggesting that cells in contact with the electrode were primarily responsible for current generation. These data, along with cryo-electron microscopy experiments, support contact-dependent electron transfer by T. potens strain JR from the cell membrane across the 37-nm cell envelope to the cell surface. Furthermore, we present physiological and genomic evidence that c-type cytochromes play a role in charge transfer across the Gram-positive bacterial cell envelope during metal reduction. PMID:21908627

  18. Production of a bacteriocin by a poultry derived Campylobacter jejuni isolate with antimicrobial activity against Clostridium perfringens and other Gram positive bacteria.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have purified a bacteriocin peptide (termed CUV-3), produced by a poultry cecal isolate of Campylobacter jejuni (strain CUV-3) with inhibitory activity against Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staphylococcus epidermidis and Listeria mon...

  19. Isolation and Characterization of Four Gram-PositiveNickel-Tolerant Microorganisms from Contaminated Riparian Sediments

    SciTech Connect

    Van Nostrand, Joy D.; Khijniak, Tatiana V.; Gentry, Terry J.; Novak, Michelle T.; Sowder, Andrew G.; Zhou, Jizhong Z.; Bertsch, PaulM.; Morris, Pamela J.

    2006-08-30

    Microbial communities from riparian sediments contaminatedwith high levels of Ni and U were examined for metal-tolerantmicroorganisms. Isolation of four aerobic Ni-tolerant, Gram-positiveheterotrophic bacteria indicated selection pressure from Ni. Theseisolates were identified as Arthrobacter oxydans NR-1, Streptomycesgalbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatosporacystarginea NR-4 based on partial 16S rDNA sequences. A functional genemicroarray containing gene probes for functions associated withbiogeochemical cycling, metal homeostasis, and organic contaminantdegradation showed little overlap among the four isolates. Fifteen of thegenes were detected in all four isolates with only two of these relatedto metal resistance, specifically to tellurium. Each of the four isolatesalso displayed resistance to at least one of six antibiotics tested, withresistance to kanamycin, gentamycin, and ciprofloxacin observed in atleast two of the isolates. Further characterization of S. aureofaciensNR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Nitolerance constitutively. In addition, both were able to grow in higherconcentrations of Ni at pH 6 as compared to pH 7 (42.6 and 8.5 mM Ni atpH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examinedin these two isolates; a similar pH-dependent metal tolerance wasobserved when grown with Co and Zn. Neither isolate was tolerant to Cd.These findings suggest that Ni is exerting a selection pressure at thissite for metal-resistant actinomycetes.

  20. Gram-Positive Nickel Resistant Bacteria Isolated from Riparian Sediments Contaminated with Ni and U on the Savannah River Site

    NASA Astrophysics Data System (ADS)

    Sowder, A. G.; Khijniak, T. V.; van Nostrand, J.; Bertsch, P. M.; Morris, P. J.

    2002-12-01

    The natural attenuation of pollutants in riparian and wetland systems is driven in large part by the services provided by the diverse microbial communities that thrive in these nutritionally and chemically complex environments. For co-contaminated systems, the presence of heavy metals at excessive levels may alter the structure and function of microbial communities that are essential for the immobilization of inorganics and degradation of organic contaminants. We examined riparian sediments heavily contaminated with U and Ni (1000's of mg/kg) from a small stream on the U.S. Department of Energy's Savannah River Site that received metallurgical process effluents wastewater over a thirty-year period associated with the production of nuclear materials. Four gram positive bacteria were isolated that displayed marked resistance (5000 mg/kg) to Ni relative to organisms from uncontaminated control locations: Arthrobacter oxydans, Streptomyces galbus, Streptomyces aureofaciens, and Kitasatospora cystarginea. The metal resistance of S. aureofaciens and K. cystarginea was further characterized in growth experiments for resistance to other metals. Ongoing geochemical characterization of U and Ni in terms of solid phase partitioning and aqueous phase speciation and solubility indicate that Ni is more chemically labile and, by extension, bioavailable than U in these aged-contaminated sediments. Accordingly, the isolation of Ni resistant organisms is consistent with greater selective pressure from Ni as a result of its greater bioavailability. These results are placed in context of environmental management and remediation of co-contaminated, biogeochemically complex environments.

  1. A poultry-intestinal isolate of Campylobacter jejuni produces a bacteriocin (CUV-3) active against a range of Gram positive bacterial pathogens including Clostridium perfringens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A newly isolated bacteriocin, CUV-3, produced by a poultry cecal isolate of Campylobacter jejuni strain CUV-3 had inhibitory activity against several Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staph.epidermidis and Listeria monocytogenes. The pept...

  2. Application of different molecular techniques for characterization of catalase-positive cocci isolated from sucuk.

    PubMed

    Kesmen, Zülal; Yarimcam, Burcu; Aslan, Hakiye; Ozbekar, Esra; Yetim, Hasan

    2014-02-01

    This study was carried out for the characterization and discrimination of the indigenous Gram positive, catalase-positive cocci (GCC) population in sucuk, a traditional Turkish dry-fermented sausage. Sucuk samples, produced by the traditional method without starter culture were collected from 8 local producers in Kayseri/Turkey and a total of 116 GCC isolates were identified by using different molecular techniques. Two different molecular fingerprinting methods; namely, randomly amplified polymorphic DNA-PCR (RAPD-PCR) and repetitive extragenic palindrome-PCR (rep-PCR), were used for the clustering of isolates and identification at species level was carried out by full length sequencing of 16S rDNA. Combining the results obtained from molecular fingerprinting and 16S rDNA sequencing showed that the dominant GCC species isolated from the sucuk samples was Staphylococcus saprophyticus followed by Staphylococcus succinus and Staphylococcus equorum belonging to the Staphylococcus genus. Real-time PCR DNA melting curve analysis and high-resolution melting (HRM) analysis targeting the V1 + V3 regions of 16S rDNA were also applied for the discrimination of isolates belonging to different species. It was observed statistically different Tm values and species-specific HRM profiles for all except 2 species (S. saprophyticus and Staphylococcus xylosus) that have high 16S rDNA sequence similarity. The combination of rep-PCR and/or PCR-RAPD with 16S rRNA gene sequencing was an efficient approach for the characterization and identification of the GCC population in spontaneously fermented sucuk. On the other hand, intercalating dye assays were found to be a simple and very promising technique for the differentiation of the GCC population at species level. PMID:24410408

  3. Phenotypic antimicrobial susceptibility and occurrence of selected resistance genes in gram-positive mastitis pathogens isolated from Wisconsin dairy cows.

    PubMed

    Ruegg, P L; Oliveira, L; Jin, W; Okwumabua, O

    2015-07-01

    . uberis carried multiple resistance genes. Results indicate that most gram-positive mastitis organisms were susceptible to most antimicrobials used for intramammary administration, but some resistance to drugs used for systemic treatment of mastitis was noted. The presence of selected resistance genes was not proportional to the occurrence of phenotypic resistance. PMID:25912858

  4. Differential toxicity of Al2O3 particles on Gram-positive and Gram-negative sediment bacterial isolates from freshwater.

    PubMed

    Bhuvaneshwari, M; Bairoliya, Sakcham; Parashar, Abhinav; Chandrasekaran, N; Mukherjee, Amitava

    2016-06-01

    The current study was aimed to explore the differential effects on Gram-positive and Gram-negative freshwater sediment bacterial isolates upon exposure to nano-particles and bulk particles of Al2O3 at low concentrations (0.25, 0.5, and 1 mg/L). The Gram-negative Pseudomonas aeruginosa was more susceptible to both the nano-forms and bulk forms than the Gram-positive Bacillus altitudinis. The generation of reactive oxygen species (ROS) and release of lipopolysaccharide due to membrane damage were dependent on the dose of nano-Al2O3. The Fourier transform infrared spectroscopy (FT-IR) studies confirmed the attachment of nano-Al2O3 on bacterial cells, which may lead to subsequent changes in the cell membrane composition and integrity. Internalization of nano-Al2O3 was estimated to be more for P. aeruginosa than for B. altitudinis cells. As a role of defense mechanism, the biofilm formation and production of extracellular polymeric substances (EPSs; polysaccharide and protein) were increased with respect to the concentration of toxicant. Nano-Al2O3 was estimated to cause more DNA damage than the bulk particles in both Gram-positive and Gram-negative bacterial strains. PMID:26965278

  5. In Vitro Activity of Plazomicin against 5,015 Gram-Negative and Gram-Positive Clinical Isolates Obtained from Patients in Canadian Hospitals as Part of the CANWARD Study, 2011-2012

    PubMed Central

    Adam, H.; Baxter, M.; Denisuik, A.; Lagacé-Wiens, P.; Karlowsky, J. A.; Hoban, D. J.; Zhanel, G. G.

    2014-01-01

    Plazomicin is a next-generation aminoglycoside that is not affected by most clinically relevant aminoglycoside-modifying enzymes. The in vitro activities of plazomicin and comparator antimicrobials were evaluated against a collection of 5,015 bacterial isolates obtained from patients in Canadian hospitals between January 2011 and October 2012. Susceptibility testing was performed using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method, with MICs interpreted according to CLSI breakpoints, when available. Plazomicin demonstrated potent in vitro activity against members of the family Enterobacteriaceae, with all species except Proteus mirabilis having an MIC90 of ≤1 μg/ml. Plazomicin was active against aminoglycoside-nonsusceptible Escherichia coli, with MIC50 and MIC90 values identical to those for aminoglycoside-susceptible isolates. Furthermore, plazomicin demonstrated equivalent activities versus extended-spectrum β-lactamase (ESBL)-producing and non-ESBL-producing E. coli and Klebsiella pneumoniae, with 90% of the isolates inhibited by an MIC of ≤1 μg/ml. The MIC50 and MIC90 values for plazomicin against Pseudomonas aeruginosa were 4 μg/ml and 16 μg/ml, respectively, compared with 4 μg/ml and 8 μg/ml, respectively, for amikacin. Plazomicin had an MIC50 of 8 μg/ml and an MIC90 of 32 μg/ml versus 64 multidrug-resistant P. aeruginosa isolates. Plazomicin was active against methicillin-susceptible and methicillin-resistant Staphylococcus aureus, with both having MIC50 and MIC90 values of 0.5 μg/ml and 1 μg/ml, respectively. In summary, plazomicin demonstrated potent in vitro activity against a diverse collection of Gram-negative bacilli and Gram-positive cocci obtained over a large geographic area. These data support further evaluation of plazomicin in the clinical setting. PMID:24550325

  6. A simple and efficient Triton X-100 boiling and chloroform extraction method of RNA isolation from Gram-positive and Gram-negative bacteria.

    PubMed

    Sung, Kidon; Khan, Saeed A; Nawaz, Mohamed S; Khan, Ashraf A

    2003-12-01

    A fast, reliable, and inexpensive Triton X-100 boiling procedure for RNA isolation from both the Gram-positive and Gram-negative bacteria was developed. The yield of RNA was 0.2-2 mg per 10 ml bacterial culture. The method was tested on Gram-positive and Gram-negative bacteria of eight genera and nine species and yielded reproducible results. In parallel experiments, the Qiagen and hot phenol extraction methods both yielded RNA that contained contaminating 16S and 23S rRNA. The Triton X-100 boiling method reported here yielded RNA that was free from 16S and 23S rRNA, contained full-length transcripts and did not require additional purification. The presence of specific mRNA in one of the RNA samples obtained by this procedure was demonstrated by partial amplification of a 732 bp vancomycin resistance gene, vanA, by reverse transcription-polymerase chain reaction (RT-PCR). The presence of a full-length transcript (1031 bases) of the vanA gene was verified by Northern hybridization and probing with a digoxigenin (DIG)-labeled vanA PCR partial product. The method provides a rapid, reliable, and simple tool for the isolation of good quality RNA suitable for various molecular biology experiments. PMID:14659548

  7. In vitro activity of tedizolid against gram-positive bacteria in patients with skin and skin structure infections and hospital-acquired pneumonia: a Korean multicenter study.

    PubMed

    Lee, Yangsoon; Hong, Sung Kuk; Choi, Sunghak; Im, Weonbin; Yong, Dongeun; Lee, Kyungwon

    2015-09-01

    We compared the activities of tedizolid to those of linezolid and other commonly used antimicrobial agents against gram-positive cocci recovered from patients with skin and skin structure infections (SSSIs) and hospital-acquired pneumonia (HAP) in Korean hospitals. Gram-positive isolates were collected from 356 patients with SSSIs and 144 patients with HAP at eight hospitals in Korea from 2011 to 2014. SSSIs included impetigo, cellulitis, erysipelas, furuncles, abscesses, and infected burns. Antimicrobial susceptibility was tested by using the CLSI agar dilution method. All of the gram-positive isolates were inhibited by ≤1 μg/mL tedizolid. The minimum inhibitory concentration [MIC]₉₀ of tedizolid was 0.5 μg/mL for methicillin-resistant Staphylococcus aureus, which was 4-fold lower than that of linezolid. Tedizolid may become a useful option for the treatment of SSSIs and HAP caused by gram-positive bacteria. PMID:26206690

  8. In Vitro Activities of Daptomycin, Vancomycin, Quinupristin- Dalfopristin, Linezolid, and Five Other Antimicrobials against 307 Gram-Positive Anaerobic and 31 Corynebacterium Clinical Isolates

    PubMed Central

    Goldstein, Ellie J. C.; Citron, Diane M.; Merriam, C. Vreni; Warren, Yumi A.; Tyrrell, Kerrin L.; Fernandez, Helen T.

    2003-01-01

    The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The daptomycin MICs determined on Ca2+-supplemented (50 mg/liter) brucella agar plates were one- to fourfold lower than those determined in unsupplemented media. Daptomycin was highly active (MICs, ≤2 μg/ml) against many strains including 36 of 37 peptostreptococci, 37 of 48 isolates of the Eubacterium group, and all strains of Propionibacterium spp., Clostridium perfringens, Clostridium difficile, and other Clostridium spp. It was fourfold or greater more active than vancomycin against Clostridium innocuum and 16 of 34 strains of vancomycin-resistant lactobacilli. Three strains of C. difficile for which quinupristin-dalfopristin and linezolid MICs were >8 μg/ml were inhibited by <1 μg of daptomycin per ml. Daptomycin MICs were ≥4 μg/ml for most strains of Clostridium clostridioforme, Clostridium paraputrificum, Clostridium tertium, and Clostridium ramosum; the isolates were generally more resistant to other antimicrobials. Daptomycin was two- to fourfold less active against Actinomyces spp. than vancomycin, quinupristin-dalfopristin, or linezolid. Twenty-nine of 31 strains of Corynebacterium spp., including Corynebacterium jeikeium, Corynebacterium amycolatum, and Corynebacterium pseudodiphtheriticum, were inhibited by ≤0.25 μg of daptomycin per ml. For two strains of “Corynebacterium aquaticum,” 8 μg of daptomycin per ml was required for inhibition. Daptomycin demonstrated very good activities against a broad range of gram-positive organisms including vancomycin-resistant C. innocuum and lactobacillus strains and quinupristin-dalfopristin- and linezolid-resistant C. difficile strains. PMID:12499210

  9. In vitro activity of dalbavancin and five comparator agents against common and uncommon Gram-positive organisms isolated from cancer patients.

    PubMed

    Rolston, Kenneth V I; Wang, Weiqun; Nesher, Lior; Shelburne, Samuel A; Prince, Randall A

    2016-05-01

    Dalbavancin is a long acting, bactericidal lipoglycopeptide. Its in vitro activity was compared with that of vancomycin, daptomycin, linezolid, trimethoprim/sulfamethoxazole (TMP/SMX) and levofloxacin against 241 Gram-positive organisms isolated from cancer patients. The rank order of potency for the glycopeptides based on MIC90 (μg ml(-1)), that is, the concentration of antimicrobial agent required to inhibit 90% of isolates tested was dalbavancin (0.12 μg ml(-1))>daptomycin (1.0 μg ml(-1))>vancomycin (2.0 μg ml(-1)) for coagulase-negative staphylococci and Staphylococcus aureus isolates (including methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains). Dalbavancin had potent activity against staphylococcal isolates with vancomycin MICs⩾1.0 μg ml(-1). TMP/SMX also had potent activity against staphylococci including methicillin-resistant strains, whereas levofloxacin had moderate to poor anti-staphylococcal activity. Dalbavancin also exhibited more potent activity than vancomycin and daptomycin against Bacillus spp., Corynebacterium spp., Micrococcus spp. and various streptococci (including Streptococcus pneumoniae, viridans group streptococci (VGS), beta-hemolytic streptococci and gamma-hemolytic streptococci). MBC determinations showed that dalbavancin had potent bactericidal activity against MRSA with no tolerance being detected. These data suggest that dalbavancin may be considered as an alternative to vancomycin, especially in institutions wherein a substantial proportion of infections are caused by organisms with vancomycin MICs⩾1.0 μg ml(-1). PMID:26626876

  10. Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.

    PubMed

    D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

    2014-12-01

    The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological

  11. Daptomycin: a novel lipopeptide antibiotic against Gram-positive pathogens

    PubMed Central

    Beiras-Fernandez, Andres; Vogt, Ferdinand; Sodian, Ralf; Weis, Florian

    2010-01-01

    The aim of this review is to summarize the historical background of drug resistance of Gram-positive pathogens as well as to describe in detail the novel lipopeptide antibiotic daptomycin. Pharmacological and pharmacokinetic aspects are reviewed and the current clinical use of daptomycin is presented. Daptomycin seems to be a reliable drug in the treatment of complicated skin and skin structure infections, infective right-sided endocarditis, and bacteremia caused by Gram-positive agents. Its unique mechanism of action and its low resistance profile, together with its rapid bactericidal action make it a favorable alternative to vancomycin in multi-drug resistant cocci. The role of daptomycin in the treatment of prosthetic material infections, osteomyelitis, and urogenital infections needs to be evaluated in randomized clinical trials. PMID:21694898

  12. Isolation and Structural Elucidation of Brevibacillin, an Antimicrobial Lipopeptide from Brevibacillus laterosporus That Combats Drug-Resistant Gram-Positive Bacteria.

    PubMed

    Yang, Xu; Huang, En; Yuan, Chunhua; Zhang, Liwen; Yousef, Ahmed E

    2016-05-01

    A new environmental bacterial strain exhibited strong antimicrobial characteristics against methicillin-resistantStaphylococcus aureus, vancomycin-resistant strains ofEnterococcus faecalisandLactobacillus plantarum, and other Gram-positive bacteria. The producer strain, designated OSY-I1, was determined to beBrevibacillus laterosporusvia morphological, biochemical, and genetic analyses. The antimicrobial agent was extracted from cells of OSY-I1with isopropanol, purified by high-performance liquid chromatography, and structurally analyzed using mass spectrometry (MS) and nuclear magnetic resonance (NMR). The MS and NMR results, taken together, uncovered a linear lipopeptide consisting of 13 amino acids and an N-terminal C6fatty acid (FA) chain, 2-hydroxy-3-methylpentanoic acid. The lipopeptide (FA-Dhb-Leu-Orn-Ile-Ile-Val-Lys-Val-Val-Lys-Tyr-Leu-valinol, where Dhb is α,β-didehydrobutyric acid and valinol is 2-amino-3-methyl-1-butanol) has a molecular mass of 1,583.0794 Da and contains three modified amino acid residues: α,β-didehydrobutyric acid, ornithine, and valinol. The compound, designated brevibacillin, was determined to be a member of a cationic lipopeptide antibiotic family. In addition to its potency against drug-resistant bacteria, brevibacillin also exhibited low MICs (1 to 8 μg/ml) against selected foodborne pathogenic and spoilage bacteria, such asListeria monocytogenes,Bacillus cereus, andAlicyclobacillus acidoterrestris Purified brevibacillin showed no sign of degradation when it was held at 80°C for 60 min, and it retained at least 50% of its antimicrobial activity when it was held for 22 h under acidic or alkaline conditions. On the basis of these findings, brevibacillin is a potent antimicrobial lipopeptide which is potentially useful to combat drug-resistant bacterial pathogens and foodborne pathogenic and spoilage bacteria. PMID:26921428

  13. Transformation of gram positive bacteria by sonoporation

    DOEpatents

    Yang, Yunfeng; Li, Yongchao

    2014-03-11

    The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

  14. Activities of Tedizolid and Linezolid Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe, and Latin American Countries in 2014.

    PubMed

    Pfaller, Michael A; Flamm, Robert K; Jones, Ronald N; Farrell, David J; Mendes, Rodrigo E

    2016-09-01

    Tedizolid and linezolid in vitro activities against 3,032 Gram-positive pathogens collected in Asia-Pacific, Eastern European, and Latin American medical centers during 2014 were assessed. The isolates were tested for susceptibility by the current reference broth microdilution methods. Due to concern over the effect of MIC endpoint criteria on the results of testing the oxazolidinones tedizolid and linezolid, MIC endpoint values were read by two methods: (i) reading the MIC at the first well where the trailing began without regard for pinpoint trailing, according to CLSI M07-A10 and M100-S26 document instructions for reading linezolid (i.e., 80% inhibition of growth; these reads were designated tedizolid 80 and linezolid 80), and (ii) at 100% inhibition of growth (designated tedizolid 100 and linezolid 100). All Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group, and Enterococcus faecalis isolates were inhibited at tedizolid 80 and 100 MIC values of 0.25 and 0.5, 0.25 and 0.25, 0.25 and 0.5, 0.12 and 0.25, and 0.5 and 1 μg/ml, respectively. Generally, MIC50 and MIC90 results for tedizolid 80 and linezolid 80 were one doubling dilution lower than those read at 100% inhibition. Tedizolid was 4- to 8-fold more potent than linezolid against all the isolates tested regardless of the MIC endpoint criterion used. Despite the differences in potency, >99.9% of isolates tested in this survey were susceptible to both linezolid and tedizolid using CLSI and EUCAST interpretive criteria. In conclusion, tedizolid demonstrated greater in vitro potency than linezolid against Gram-positive pathogens isolated from patients in medical centers across the Asia-Pacific region, Eastern Europe, and Latin America. PMID:27353270

  15. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance.

    PubMed

    Valle, Demetrio L; Cabrera, Esperanza C; Puzon, Juliana Janet M; Rivera, Windell L

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria. PMID

  16. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance

    PubMed Central

    Valle, Demetrio L.; Cabrera, Esperanza C.; Puzon, Juliana Janet M.; Rivera, Windell L.

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria. PMID

  17. Isolation and Purification of Enteroicin E-760 with a Broad Antimicrobial Activity Against Gram-positive and Gram-negative Bacteria (AAC01569-06 Version 3)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Strain NRRL B-30745, isolated from chicken ceca, and identified as an Enterococcus spp. of the durans/faecium/hirae group, produces a 5362 Da bacteriocin that inhibits the growth of Salmonella enteritidis, S. choleraesuis, S. typhimurium, S. gallinarum, Escherichia coli O157:H7, Yersinia enterocolit...

  18. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, L.O.; Barbosa-Alleyne, M.D.F.

    1996-01-09

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

  19. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, L.O.; Barbosa-Alleyne, M.D.F.

    1999-06-29

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

  20. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal; Barbosa-Alleyne, Maria D. F.

    1996-01-01

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

  1. Ethanol production in gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal; Barbosa-Alleyne, Maria D. F.

    1999-01-01

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

  2. Bacteriocins of gram-positive bacteria.

    PubMed Central

    Jack, R W; Tagg, J R; Ray, B

    1995-01-01

    In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following

  3. [New antimicrobials against Gram-positive organisms].

    PubMed

    Montejo, M

    2008-01-01

    Glycopeptides have been the antimicrobials most commonly used for infections by Gram-positive organisms and methicillin resistant S. aureus (MRSA). In recent years, however, glycopeptide resistance and tolerance have become a serious problem. Thus, enterococci highly resistant to vancomycin, vancomycin-intermediate/ resistant S. aureus (VISA), and vancomycin tolerance in S. aureus are found, and increased therapeutic failure and mortality are clinically reported with vancomycin MIC for S. aureus > or = 1.5-2 microg/mL. When faced with these organisms, we therefore need potent bactericidal antimicrobials that may be empirically administered, effective against susceptible and resistant pathogens, easily dosed, with few adverse effects and no significant interaction with other drugs, and that can be administered in an outpatient setting. In bacteremia by methicillin-susceptible S. aureus, use of vancomycin is associated to a greater failure and mortality rate as compared to semisynthetic penicillins. New treatment options for MRSA infections include daptomycin, linezolid, tygecycline, and quinupristin/dalfopristin. New anti-MRSA drugs are also under development, including glycopeptides (dalbavancin, telavancin, and oritavancin), ceftobiprole, and iclaprim. This paper reviews the new antimicrobials against Gram-positive organisms. PMID:18957022

  4. Peptide conversations in Gram-positive bacteria.

    PubMed

    Monnet, Véronique; Juillard, Vincent; Gardan, Rozenn

    2016-05-01

    Within Gram-positive bacteria, the expression of target genes is controlled at the population level via signaling peptides, also known as pheromones. Pheromones control a wide range of functions, including competence, virulence, and others that remain unknown. Until now, their role in bacterial gene regulation has probably been underestimated; indeed, bacteria are able to produce, by ribosomal synthesis or surface protein degradation, an extraordinary variety of peptides which are released outside bacteria and among which, some are pheromones that mediate cell-to-cell communication. The review aims at giving an updated overview of these peptide-dependant communication pathways. More specifically, it follows the whole peptide circuit from the peptide production and secretion in the extracellular medium to its interaction with sensors at bacterial surface or re-import into the bacteria where it plays its regulation role. In recent years, as we have accumulated more knowledge about these systems, it has become apparent that they are more complex than they first appeared. For this reason, more research on peptide-dependant pathways is needed to develop new strategies for controlling functions of interest in Gram-positive bacteria. In particular, such research could lead to alternatives to the use of antibiotics against pathogenic bacteria. In perspective, the review identifies new research questions that emerge in this field and that have to be addressed. PMID:25198780

  5. [Epidemiology of the infection by resistant Gram-positive microorganisms].

    PubMed

    Cercenado, E

    2016-09-01

    Resistance among Gram-positive microorganisms to classical and new antimicrobials is a therapeutic threat. In Spain, methicillin resistance among Staphylococcus aureus (25-30%) and coagulase-negative staphylococci (50-60%) seems to have stabilized in the last decade. Among enterococci, vancomycin resistance is less than 5%. Both linezolid and daptomycin, in general, show good activity against these microorganisms. However, the resistance rates of Staphylococcus epidermidis to linezolid (20.9%), and of Enterococcus faecium to daptomycin (10.5%) in isolates from intensive care units are a worrying. PMID:27608305

  6. Gram-Positive Uropathogens, Polymicrobial Urinary Tract Infection, and the Emerging Microbiota of the Urinary Tract

    PubMed Central

    Kline, Kimberly A.; Lewis, Amanda L.

    2015-01-01

    Gram-positive bacteria are a common cause of urinary tract infection (UTI), particularly among individuals who are elderly, pregnant, or who have other risk factors for UTI. Here we review the epidemiology, virulence mechanisms, and host response to the most frequently isolated Gram-positive uropathogens: Staphylococcus saprophyticus, Enterococcus faecalis, and Streptococcus agalactiae. We also review several emerging, rare, misclassified, and otherwise underreported Gram-positive pathogens of the urinary tract including Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella. The literature strongly suggests that urologic diseases involving Gram-positive bacteria may be easily overlooked due to limited culture-based assays typically utilized for urine in hospital microbiology laboratories. Some UTIs are polymicrobial in nature, often involving one or more Gram-positive bacteria. We herein review the risk factors and recent evidence for mechanisms of bacterial synergy in experimental models of polymicrobial UTI. Recent experimental data has demonstrated that, despite being cleared quickly from the bladder, some Gram-positive bacteria can impact pathogenic outcomes of co-infecting organisms. When taken together, the available evidence argues that Gram-positive bacteria are important uropathogens in their own right, but that some can be easily overlooked because they are missed by routine diagnostic methods. Finally, a growing body of evidence demonstrates that a surprising variety of fastidious Gram-positive bacteria may either reside in or be regularly exposed to the urinary tract and further suggests that their presence is widespread among women, as well as men. Experimental studies in this area are needed; however, there is a growing appreciation that the composition of bacteria found in the bladder could be a potentially important determinant in urologic disease, including susceptibility to UTI. PMID:27227294

  7. Gram-Positive Uropathogens, Polymicrobial Urinary Tract Infection, and the Emerging Microbiota of the Urinary Tract.

    PubMed

    Kline, Kimberly A; Lewis, Amanda L

    2016-04-01

    Gram-positive bacteria are a common cause of urinary-tract infection (UTI), particularly among individuals who are elderly, pregnant, or who have other risk factors for UTI. Here we review the epidemiology, virulence mechanisms, and host response to the most frequently isolated Gram-positive uropathogens: Staphylococcus saprophyticus, Enterococcus faecalis, and Streptococcus agalactiae. We also review several emerging, rare, misclassified, and otherwise underreported Gram-positive pathogens of the urinary tract including Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella. The literature strongly suggests that urologic diseases involving Gram-positive bacteria may be easily overlooked due to limited culture-based assays typically utilized for urine in hospital microbiology laboratories. Some UTIs are polymicrobial in nature, often involving one or more Gram-positive bacteria. We herein review the risk factors and recent evidence for mechanisms of bacterial synergy in experimental models of polymicrobial UTI. Recent experimental data has demonstrated that, despite being cleared quickly from the bladder, some Gram-positive bacteria can impact pathogenic outcomes of co-infecting organisms. When taken together, the available evidence argues that Gram-positive bacteria are important uropathogens in their own right, but that some can be easily overlooked because they are missed by routine diagnostic methods. Finally, a growing body of evidence demonstrates that a surprising variety of fastidious Gram-positive bacteria may either reside in or be regularly exposed to the urinary tract and further suggests that their presence is widespread among women, as well as men. Experimental studies in this area are needed; however, there is a growing appreciation that the composition of bacteria found in the bladder could be a potentially important determinant in urologic disease, including susceptibility to UTI. PMID:27227294

  8. Methods for targetted mutagenesis in gram-positive bacteria

    SciTech Connect

    Yang, Yunfeng

    2014-05-27

    The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

  9. Glass bead transformation method for gram-positive bacteria

    PubMed Central

    Rattanachaikunsopon, Pongsak; Phumkhachorn, Parichat

    2009-01-01

    A simple, inexpensive and reproducible transformation method was developed for Gram-positive bacteria. It was based on agitation of bacterial protoplasts with glass beads in the presence of DNA and polyethylene glycol. By using this method, introduction of pGK12 into protoplasts of several strains of Gram-positive bacteria was achieved. PMID:24031442

  10. Case-Control Study of Telavancin as an Alternative Treatment for Gram-Positive Bloodstream Infections in Patients with Cancer.

    PubMed

    Chaftari, Anne-Marie; Hachem, Ray; Jordan, Mary; Garoge, Kumait; Al Hamal, Zainab; El Zakhem, Aline; Viola, George M; Granwehr, Bruno; Mulanovich, Victor; Gagel, Andrew; Reitzel, Ruth; Yousif, Ammar; Jiang, Ying; Raad, Issam

    2016-01-01

    Gram-positive bacterial infections are an important cause of morbidity and death among cancer patients, despite current therapy. In this case-control study, we evaluated the clinical outcomes and safety of telavancin in cancer patients with uncomplicated Gram-positive bloodstream infections (BSIs). Between March 2011 and May 2013, we enrolled cancer patients with uncomplicated Gram-positive BSIs to receive intravenous telavancin therapy for at least 14 days for Staphylococcus aureus and 7 days for other Gram-positive cocci. Patients with baseline creatinine clearance (CLCR) values of >50 ml/min received 10 mg/kg/day of telavancin, and those with CLCR values between 30 and 49 ml/min received 7.5 mg/kg/day. Patients were compared with a retrospective cohort of 39 historical patients with Gram-positive BSIs, matched for underlying malignancy, infecting organism, and neutropenia status, who had been treated with vancomycin. A total of 78 patients were analyzed, with 39 in each group. The most common pathogen causing BSIs was S. aureus (51%), followed by alpha-hemolytic streptococci (23%), Enterococcus spp. (15%), coagulase-negative staphylococci (8%), and beta-hemolytic streptococci (3%). Sixty-two percent of patients had hematological malignancies, and 38% had solid tumors; 51% of the patients were neutropenic. The overall response rate determined by clinical outcome and microbiological eradication at 72 h following the initiation of therapy, in the absence of relapse, deep-seated infections, and/or infection-related death, was better with telavancin than with vancomycin (86% versus 61%; P = 0.013). Rates of drug-related adverse events were similar in the two groups (telavancin, 31%; vancomycin, 23%; P = 0.79), with similar rates of renal adverse events. Telavancin may provide a useful alternative to standard vancomycin therapy for Gram-positive BSIs in cancer patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01321879.). PMID

  11. Case-Control Study of Telavancin as an Alternative Treatment for Gram-Positive Bloodstream Infections in Patients with Cancer

    PubMed Central

    Hachem, Ray; Jordan, Mary; Garoge, Kumait; Al Hamal, Zainab; El Zakhem, Aline; Viola, George M.; Granwehr, Bruno; Mulanovich, Victor; Gagel, Andrew; Reitzel, Ruth; Yousif, Ammar; Jiang, Ying; Raad, Issam

    2015-01-01

    Gram-positive bacterial infections are an important cause of morbidity and death among cancer patients, despite current therapy. In this case-control study, we evaluated the clinical outcomes and safety of telavancin in cancer patients with uncomplicated Gram-positive bloodstream infections (BSIs). Between March 2011 and May 2013, we enrolled cancer patients with uncomplicated Gram-positive BSIs to receive intravenous telavancin therapy for at least 14 days for Staphylococcus aureus and 7 days for other Gram-positive cocci. Patients with baseline creatinine clearance (CLCR) values of >50 ml/min received 10 mg/kg/day of telavancin, and those with CLCR values between 30 and 49 ml/min received 7.5 mg/kg/day. Patients were compared with a retrospective cohort of 39 historical patients with Gram-positive BSIs, matched for underlying malignancy, infecting organism, and neutropenia status, who had been treated with vancomycin. A total of 78 patients were analyzed, with 39 in each group. The most common pathogen causing BSIs was S. aureus (51%), followed by alpha-hemolytic streptococci (23%), Enterococcus spp. (15%), coagulase-negative staphylococci (8%), and beta-hemolytic streptococci (3%). Sixty-two percent of patients had hematological malignancies, and 38% had solid tumors; 51% of the patients were neutropenic. The overall response rate determined by clinical outcome and microbiological eradication at 72 h following the initiation of therapy, in the absence of relapse, deep-seated infections, and/or infection-related death, was better with telavancin than with vancomycin (86% versus 61%; P = 0.013). Rates of drug-related adverse events were similar in the two groups (telavancin, 31%; vancomycin, 23%; P = 0.79), with similar rates of renal adverse events. Telavancin may provide a useful alternative to standard vancomycin therapy for Gram-positive BSIs in cancer patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01321879.) PMID

  12. First Report of Human Infection by Agromyces mediolanus, a Gram-Positive Organism Found in Soil.

    PubMed

    Sridhar, Siddharth; Wang, Angela Y M; Chan, Jasper F W; Yip, Cyril C Y; Lau, Susanna K P; Woo, Patrick C Y; Yuen, Kwok-Yung

    2015-10-01

    We report the first human infection by a member of the Agromyces genus, a group of Gram-positive bacteria found in soil. A patient with a long-term venous catheter developed bacteremia due to a non-vancomycin-susceptible isolate of Agromyces mediolanus. Rapid identification was possible by matrix-assisted laser desorption ionization-time of flight mass spectrometry. PMID:26202108

  13. First Report of Human Infection by Agromyces mediolanus, a Gram-Positive Organism Found in Soil

    PubMed Central

    Sridhar, Siddharth; Wang, Angela Y. M.; Chan, Jasper F. W.; Yip, Cyril C. Y.; Woo, Patrick C. Y.; Yuen, Kwok-Yung

    2015-01-01

    We report the first human infection by a member of the Agromyces genus, a group of Gram-positive bacteria found in soil. A patient with a long-term venous catheter developed bacteremia due to a non-vancomycin-susceptible isolate of Agromyces mediolanus. Rapid identification was possible by matrix-assisted laser desorption ionization–time of flight mass spectrometry. PMID:26202108

  14. [Comparative urinary bactericidal activity of oral antibiotics against gram-positive pathogens].

    PubMed

    Bedenić, Branka; Budimir, Ana; Gverić, Ana; Plecko, Vanda; Vranes, Jasmina; Bubonja-Sonje, Marina; Kalenić, Smilja

    2012-01-01

    In routine bacteriological laboratories the antibacterial activity of antibiotics is determined by in vitro testing, usually by disk-diffusion test. However, in vitro testing does not always reflect antibacterial efficiency of antibiotics in vivo. In this investigation, the urine samples obtained in a single oral dose pharmacokinetic study were examined for their bactericidal activity against a range of relevant Gram-positive urinary tract pathogens. Urinary bactericidal activity of linezolid had been previously compared with ciprofloxacin but not with other oral antibiotics such as beta-lactams. Linezolid showed satisfactory urinary bactericidal titres throughout the whole testing period against all Gram-positive cocci. Fluoroquinolones displayed high and persisting levels of urinary bactericidal activity against staphylococci, but their activity against enterococci was weaker. According to the results of ex-vivo testing amoxycillin could be recommended only for infections caused by E. faecalis. Amoxycillin combined with clavulanic acid can be considered as a therapeutic option for infections caused by S. saprophyticus and E. faecalis. Older cephalosporins had high titres only against S. saprophyticus. Their drawback is a short elimination half-time in urine resulting in rapid decrease of urinary bactericidal titers during dosing interval. Furthermore, they do not show activity against enterococci due to their intrinsic resistance to cephalosporins. PMID:22930932

  15. Identification of Aerobic Gram-Positive Bacilli by Use of Vitek MS

    PubMed Central

    Navas, Maria; Pincus, David H.; Wilkey, Kathy; Sercia, Linda; LaSalvia, Margaret; Wilson, Deborah; Procop, Gary W.

    2014-01-01

    The accuracy of Vitek MS mass spectrometric identifications was assessed for 206 clinically significant isolates of aerobic Gram-positive bacilli representing 20 genera and 38 species. The Vitek MS identifications were correct for 85% of the isolates (56.3% to the species level, 28.6% limited to the genus level), with misidentifications occurring for 7.3% of the isolates. PMID:24501030

  16. Diversity of pigmented Gram-positive bacteria associated with marine macroalgae from Antarctica.

    PubMed

    Leiva, Sergio; Alvarado, Pamela; Huang, Ying; Wang, Jian; Garrido, Ignacio

    2015-12-01

    Little is known about the diversity and roles of Gram-positive and pigmented bacteria in Antarctic environments, especially those associated with marine macroorganisms. This work is the first study about the diversity and antimicrobial activity of culturable pigmented Gram-positive bacteria associated with marine Antarctic macroalgae. A total of 31 pigmented Gram-positive strains were isolated from the surface of six species of macroalgae collected in the King George Island, South Shetland Islands. On the basis of 16S rRNA gene sequence similarities ≥99%, 18 phylotypes were defined, which were clustered into 11 genera of Actinobacteria (Agrococcus, Arthrobacter, Brachybacterium, Citricoccus, Kocuria, Labedella, Microbacterium, Micrococcus, Rhodococcus, Salinibacterium and Sanguibacter) and one genus of the Firmicutes (Staphylococcus). It was found that five isolates displayed antimicrobial activity against a set of macroalgae-associated bacteria. The active isolates were phylogenetically related to Agrococcus baldri, Brachybacterium rhamnosum, Citricoccus zhacaiensis and Kocuria palustris. The results indicate that a diverse community of pigmented Gram-positive bacteria is associated with Antartic macroalgae and suggest its potential as a promising source of antimicrobial and pigmented natural compounds. PMID:26507390

  17. Evaluation of the Bruker MALDI Biotyper for Identification of Gram-Positive Rods: Development of a Diagnostic Algorithm for the Clinical Laboratory

    PubMed Central

    Bloemberg, Guido V.; Zbinden, Reinhard; Böttger, Erik C.; Hombach, Michael

    2014-01-01

    Reported matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identification rates of Gram-positive rods (GPR) are low compared to identification rates of Gram-positive cocci. In this study, three sample preparation methods were compared for MALDI-TOF MS identification of 190 well-characterized GPR strains: direct transfer, direct transfer-formic acid preparation, and ethanol-formic acid extraction. Using the interpretation criteria recommended by the manufacturer, identification rates were significantly higher for direct transfer-formic acid preparation and ethanol-formic acid extraction than for direct transfer. Reducing the species cutoff from 2.0 to 1.7 significantly increased species identification rates. In a subsequent prospective study, 215 clinical GPR isolates were analyzed by MALDI-TOF MS, and the results were compared to those for identification using conventional methods, with discrepancies being resolved by 16S rRNA and rpoB gene analysis. Using the direct transfer-formic acid preparation and a species cutoff of 1.7, congruencies on the genus and species levels of 87.4% and 79.1%, respectively, were achieved. In addition, the rate of nonidentified isolates dropped from 12.1% to 5.6% when using an extended database, i.e., the Bruker database amended by reference spectra of the 190 GPR of the retrospective study. Our data demonstrate three ways to improve GPR identification by the Bruker MALDI Biotyper, (i) optimize sample preparation using formic acid, (ii) reduce cutoff scores for species identification, and (iii) expand the database. Based on our results, we suggest an identification algorithm for the clinical laboratory combining MALDI-TOF MS with nucleic acid sequencing. PMID:24452159

  18. Isolation, cultivation and genomic analysis of magnetosome biomineralization genes of a new genus of South-seeking magnetotactic cocci within the Alphaproteobacteria

    PubMed Central

    Morillo, Viviana; Abreu, Fernanda; Araujo, Ana C.; de Almeida, Luiz G. P.; Enrich-Prast, Alex; Farina, Marcos; de Vasconcelos, Ana T. R.; Bazylinski, Dennis A.; Lins, Ulysses

    2014-01-01

    Although magnetotactic bacteria (MTB) are ubiquitous in aquatic habitats, they are still considered fastidious microorganisms with regard to growth and cultivation with only a relatively low number of axenic cultures available to date. Here, we report the first axenic culture of an MTB isolated in the Southern Hemisphere (Itaipu Lagoon in Rio de Janeiro, Brazil). Cells of this new isolate are coccoid to ovoid in morphology and grow microaerophilically in semi-solid medium containing an oxygen concentration ([O2]) gradient either under chemoorganoheterotrophic or chemolithoautotrophic conditions. Each cell contains a single chain of approximately 10 elongated cuboctahedral magnetite (Fe3O4) magnetosomes. Phylogenetic analysis based on the 16S rRNA gene sequence shows that the coccoid MTB isolated in this study represents a new genus in the Alphaproteobacteria; the name Magnetofaba australis strain IT-1 is proposed. Preliminary genomic data obtained by pyrosequencing shows that M. australis strain IT-1 contains a genomic region with genes involved in biomineralization similar to those found in the most closely related magnetotactic cocci Magnetococcus marinus strain MC-1. However, organization of the magnetosome genes differs from M. marinus. PMID:24616719

  19. Isolation, cultivation and genomic analysis of magnetosome biomineralization genes of a new genus of South-seeking magnetotactic cocci within the Alphaproteobacteria

    SciTech Connect

    Morillo, Viviana; Abreu, Fernanda; Araujo, Ana C; de Almeida, Luiz G; Enrich-Prast, Alex; Farina, Marcos; de Vasconcelos, Ana T; Bazylinski, Dennis A; Lins, Ulysses

    2014-01-01

    Although magnetotactic bacteria (MTB) are ubiquitous in aquatic habitats, they are still considered fastidious microorganisms with regard to growth and cultivation with only a relatively low number of axenic cultures available to date. Here, we report the first axenic culture of an MTB isolated in the Southern Hemisphere (Itaipu Lagoon in Rio de Janeiro, Brazil). Cells of this new isolate are coccoid to ovoid in morphology and grow microaerophilically in semi-solid medium containing an oxygen concentration ([O2]) gradient either under chemoorganoheterotrophic or chemolithoautotrophic conditions. Each cell contains a single chain of approximately 10 elongated cuboctahedral magnetite (Fe3O4) magnetosomes. Phylogenetic analysis based on the 16S rRNA gene sequence shows that the coccoid MTB isolated in this study represents a new genus in the Alphaproteobacteria; the name Magnetofaba australis strain IT-1 is proposed. Preliminary genomic data obtained by pyrosequencing shows that M. australis strain IT-1 contains a genomic region with genes involved in biomineralization similar to those found in the most closely related magnetotactic cocci Magnetococcus marinus strain MC-1. However, organization of the magnetosome genes differs from M. marinus.

  20. Denitrification in Gram-positive bacteria: an underexplored trait.

    PubMed

    Verbaendert, Ines; De Vos, Paul; Boon, Nico; Heylen, Kim

    2011-01-01

    Denitrifying organisms are essential in removing fixed nitrogen pollutants from ecosystems (e.g. sewage sludge). They can be detrimental (e.g. for agricultural soil) and can also produce the greenhouse gas N2O (nitrous oxide). Therefore a more comprehensive understanding of this process has become increasingly important regarding its global environmental impact. Even though bacterial genome sequencing projects may reveal new data, to date the denitrification abilities and features in Gram-positive bacteria are still poorly studied and understood. The present review evaluates current knowledge on the denitrification trait in Gram-positive bacteria and addresses the likely existence of unknown denitrification genes. In addition, current molecular tools to study denitrification gene diversity in pure cultures and environmental samples seem to be highly biased, and additional novel approaches for the detection of denitrifying (Gram-positive) bacteria appear to be crucial in re-assessing the real diversity of denitrifiers. PMID:21265783

  1. A microdomain for protein secretion in Gram-positive bacteria.

    PubMed

    Rosch, Jason; Caparon, Michael

    2004-06-01

    Gram-positive bacteria face unique challenges in generating biologically active conformations for their exported proteins because they lack a dedicated compartment for folding secreted polypeptides. We have discovered that protein secretion by way of the general secretory (Sec) pathway in the important human pathogen Streptococcus pyogenes proceeds through a single microdomain. Unlike other mechanisms for asymmetry involving the Sec pathway, proteins destined for secretion are targeted to a single locus distal to either cell pole that has specialized to contain the Sec translocons. This subcellular organization may represent a paradigm for secretion common to other Gram-positive pathogens with profound implications for pathogenesis. PMID:15178803

  2. Baseline Activity of Telavancin against Gram-Positive Clinical Isolates Responsible for Documented Infections in U.S. Hospitals (2011-2012) as Determined by the Revised Susceptibility Testing Method

    PubMed Central

    Farrell, David J.; Sader, Helio S.; Flamm, Robert K.; Jones, Ronald N.

    2014-01-01

    Telavancin had MIC50 and MIC90 values of 0.03 and 0.06 μg/ml (100.0% susceptible), respectively, against methicillin-resistant and -susceptible Staphylococcus aureus. Telavancin was active against vancomycin-susceptible Enterococcus faecalis (MIC50/90, 0.12/0.12 μg/ml; 100% susceptible) and Enterococcus faecium (MIC50/90, 0.03/0.06 μg/ml), while higher MIC values were obtained against vancomycin-resistant E. faecium (MIC50/90, 1/2 μg/ml) and E. faecalis (MIC50/90, >2/>2 μg/ml). Streptococci showed telavancin modal MIC results of ≤0.015 μg/ml, except against Streptococcus agalactiae (i.e., 0.03 μg/ml). This study reestablishes the telavancin spectrum of activity against isolates recovered from the United States (2011-2012) using the revised broth microdilution method. PMID:25348529

  3. Multiple genes encoding 2,3-dihydroxybiphenyl 1,2-dioxygenase in the gram-positive polychlorinated biphenyl-degrading bacterium Rhodococcus erythropolis TA421, isolated from a termite ecosystem.

    PubMed Central

    Maeda, M; Chung, S Y; Song, E; Kudo, T

    1995-01-01

    Rhodococcus erythropolis TA421 was isolated from a termite ecosystem and is able to degrade a wide range of polychlorinated biphenyl (PCB) congeners. Genetic and biochemical analyses of the PCB catabolic pathway of this organism revealed that there are four different bphC genes (bphC1, bphC2, bphC3, and bphC4) which encode 2,3-dihydroxybiphenyl dioxygenases. As determined by Southern hybridization, none of the bphC genes exhibits homology to any other bphC gene. bphC1, bphC2, and bphC4 encode enzymes that have narrow substrate specificities and cleave the first aromatic ring in the meta position. In contrast, bphC3 encodes a meta cleavage dioxygenase with broad substrate specificity. Asturias et al. have shown that the closely related organism Rhodococcus globerulus P6 contains three different bphC genes (bphC1, bphC2, and bpHC3) which encode meta cleavage dioxygenases. The data suggest that there is a diverse family of bphC genes which encode PCB meta cleavage dioxygenases in members of the genus Rhodococcus. PMID:7574595

  4. Protein secretion and surface display in Gram-positive bacteria

    PubMed Central

    Schneewind, Olaf; Missiakas, Dominique M.

    2012-01-01

    The cell wall peptidoglycan of Gram-positive bacteria functions as a surface organelle for the transport and assembly of proteins that interact with the environment, in particular, the tissues of an infected host. Signal peptide-bearing precursor proteins are secreted across the plasma membrane of Gram-positive bacteria. Some precursors carry C-terminal sorting signals with unique sequence motifs that are cleaved by sortase enzymes and linked to the cell wall peptidoglycan of vegetative forms or spores. The sorting signals of pilin precursors are cleaved by pilus-specific sortases, which generate covalent bonds between proteins leading to the assembly of fimbrial structures. Other precursors harbour surface (S)-layer homology domains (SLH), which fold into a three-pronged spindle structure and bind secondary cell wall polysaccharides, thereby associating with the surface of specific Gram-positive microbes. Type VII secretion is a non-canonical secretion pathway for WXG100 family proteins in mycobacteria. Gram-positive bacteria also secrete WXG100 proteins and carry unique genes that either contribute to discrete steps in secretion or represent distinctive substrates for protein transport reactions. PMID:22411983

  5. Peritonitis due to uncommon gram-positive pathogens in children undergoing peritoneal dialysis

    PubMed Central

    Dotis, J; Printza, N; Papachristou, F

    2012-01-01

    Peritonitis is still the main complication of peritoneal dialysis (PD) in children. Staphylococcus, especially Staphylococcus epidermidis and Staphylococcus aureus, are the predominant species isolated, followed by Streptococcus spp. and by far by gram-negative bacteria and fungi. We describe three cases of PD-related peritonitis in pediatric patients due to uncommon gram-positive pathogens, which were treated with intraperitoneal antibiotic agents. PMID:23935296

  6. Multiple Responses of Gram-Positive and Gram-Negative Bacteria to Mixture of Hydrocarbons

    PubMed Central

    Marilena Lăzăroaie, Mihaela

    2010-01-01

    Most of our knowledge about pollutants and the way they are biodegraded in the environment has previously been shaped by laboratory studies using hydrocarbon-degrading bacterial strains isolated from polluted sites. In present study Gram-positive (Mycobacterium sp. IBBPo1, Oerskovia sp. IBBPo2, Corynebacterium sp. IBBPo3) and Gram-negative (Chryseomonas sp. IBBPo7, Pseudomonas sp. IBBPo10, Burkholderia sp. IBBPo12) bacteria, isolated from oily sludge, were found to be able to tolerate pure and mixture of saturated hydrocarbons, as well as pure and mixture of monoaromatic and polyaromatic hydrocarbons. Isolated Gram-negative bacteria were more tolerant to mixture of saturated (n-hexane, n-hexadecane, cyclohexane), monoaromatic (benzene, toluene, ethylbenzene) and polyaromatic (naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons than Gram-positive bacteria. There were observed cellular and molecular modifications induced by mixture of saturated, monoaromatic and polyaromatic hydrocarbons to Gram-positive and Gram-negative bacteria. These modifications differ from one strain to another and even for the same bacterial strain, according to the nature of hydrophobic substrate. PMID:24031541

  7. Cyclic diguanylate signaling in Gram-positive bacteria.

    PubMed

    Purcell, Erin B; Tamayo, Rita

    2016-09-01

    The nucleotide second messenger 3'-5' cyclic diguanylate monophosphate (c-di-GMP) is a central regulator of the transition between motile and non-motile lifestyles in bacteria, favoring sessility. Most research investigating the functions of c-di-GMP has focused on Gram-negative species, especially pathogens. Recent work in Gram-positive species has revealed that c-di-GMP plays similar roles in Gram-positives, though the precise targets and mechanisms of regulation may differ. The majority of bacterial life exists in a surface-associated state, with motility allowing bacteria to disseminate and colonize new environments. c-di-GMP signaling regulates flagellum biosynthesis and production of adherence factors and appears to be a primary mechanism by which bacteria sense and respond to surfaces. Ultimately, c-di-GMP influences the ability of a bacterium to alter its transcriptional program, physiology and behavior upon surface contact. This review discusses how bacteria are able to sense a surface via flagella and type IV pili, and the role of c-di-GMP in regulating the response to surfaces, with emphasis on studies of Gram-positive bacteria. PMID:27354347

  8. Oritavancin: a potential weapon in the battle against serious Gram-positive pathogens.

    PubMed

    Crandon, Jared; Nicolau, David P

    2008-06-01

    Oritavancin is a lipoglycopeptide antibiotic with activity against aerobic and anaerobic Gram-positive bacteria. Oritavancin separates itself from other glycopeptides through its potent in vitro activity against resistant isolates of Staphylococcus aureus, Enterococcus spp. and Streptococcus spp. Oritavancin possesses a long half-life that should allow, at maximum, once-daily dosing. Currently, oritavancin has completed two Phase III trials and one Phase II trial for the treatment of complicated skin and skin structure infections, and two Phase II trials for the treatment of Gram-positive bacteremia. In all instances, oritavancin displayed favorable outcomes and was noninferior to comparator agents (vancomycin followed by oral cephalexin) when a comparison was made. Further studies are necessary to fully characterize dose and clinical role. PMID:18505390

  9. Future trends in the treatment of serious Gram-positive infections.

    PubMed

    Metzger, Rosemarie; Bonatti, Hugo; Sawyer, Robert

    2009-01-01

    Gram-positive organisms are the most common bacterial pathogens that cause diseases in humans, with streptococci and staphylococci occurring most frequently. Immunization has been extremely successful in eradicating some Gram-positive infections, such as diphtheria and tetanus, and relatively successful for pneumococci. Staphylococcus aureus vaccines are under investigation. In terms of antimicrobial susceptibility, some Gram-positive organisms have remained sensitive to most antimicrobials, whereas others, including staphylococci, pneumococci and enterococci, have developed clinically relevant resistance. Extensive exposure to antimicrobials in the hospital setting has caused the spread of clones mainly in the hospital environment, yet multiresistance is now also found in community-acquired diseases. Community-acquired methicillin-resistant S. aureus (CA-MRSA) and resistant pneumococci are the most important examples, but even viridans streptococci are becoming resistant to some antibiotics. Moreover, MRSA and vancomycin-resistant enterococci (VRE) are found in pets and farm animals. Because of these concerns, new antimicrobials have been developed during the past decade, including quinupristin/dalfopristin, linezolid, tigecycline, daptomycin and dalbavancin. Also under investigation are beta-lactams, streptogramins and quinolones with activity against MRSA, penicillin-resistant pneumococci and VRE. Finally, infection-control measures, including the identification of carriers of multiresistant organisms and appropriate isolation, must continue to be implemented. PMID:19271030

  10. Pilins in gram-positive bacteria: A structural perspective.

    PubMed

    Krishnan, Vengadesan

    2015-07-01

    Pilins or fimbrilins are a class of proteins found in bacterial surface pilus, a hair-like surface appendage. Both the Gram-negative and -positive bacteria produce pilins to assemble pili on their cell-surface for different purposes including adherence, twitching motility, conjugation, immunomodulation, biofilm formation, and electron transfer. Immunogenic properties of the pilins make them attractive vaccine candidates. The polymerized pilins play a key role in the initiation of host adhesion, which is a critical step for bacterial colonization and infection. Because of their key role in adhesion and exposure on the cell surface, targeting the pilins-mediated adhesion (anti-adhesion therapy) is also seen as a promising alternative approach for preventing and treating bacterial infections, one that may overcome their ever-increasing repertoires of resistance mechanisms. Individual pilins interact with each other non-covalently to assemble the pilus fiber with the help of associated proteins like chaperones and Usher in Gram-negative bacteria. In contrast, the pilins in Gram-positive bacteria often connect with each other covalently, with the help of sortases. Certain unique structural features present on the pilins distinguish them from one another across different bacterial strains, and these dictate their cellular targets and functions. While the structure of pilins has been extensively studied in Gram-negative pathogenic bacteria, the pilins in Gram-positive pathogenic bacteria have been in only during the last decade. Recently, the discovery of pilins in non-pathogenic bacteria, such as Lactobacillus rhamnosus GG, has received great attention, though traditionally the attention was on pathogenic bacteria. This review summarizes and discusses the current structural knowledge of pilins in Gram-positive bacteria with emphasis on those pilins which are sortase substrates. PMID:26178080

  11. Acquired inducible antimicrobial resistance in Gram-positive bacteria

    PubMed Central

    Chancey, Scott T; Zähner, Dorothea; Stephens, David S

    2012-01-01

    A major contributor to the emergence of antibiotic resistance in Gram-positive bacterial pathogens is the expansion of acquired, inducible genetic elements. Although acquired, inducible antibiotic resistance is not new, the interest in its molecular basis has been accelerated by the widening distribution and often ‘silent’ spread of the elements responsible, the diagnostic challenges of such resistance and the mounting limitations of available agents to treat Gram-positive infections. Acquired, inducible antibiotic resistance elements belong to the accessory genome of a species and are horizontally acquired by transformation/recombination or through the transfer of mobile DNA elements. The two key, but mechanistically very different, induction mechanisms are: ribosome-sensed induction, characteristic of the macrolide–lincosamide–streptogramin B antibiotics and tetracycline resistance, leading to ribosomal modifications or efflux pump activation; and resistance by cell surface-associated sensing of β-lactams (e.g., oxacillin), glycopeptides (e.g., vancomycin) and the polypeptide bacitracin, leading to drug inactivation or resistance due to cell wall alterations. PMID:22913355

  12. Type IV Pili in Gram-Positive Bacteria

    PubMed Central

    Craig, Lisa

    2013-01-01

    SUMMARY Type IV pili (T4P) are surface-exposed fibers that mediate many functions in bacteria, including locomotion, adherence to host cells, DNA uptake (competence), and protein secretion and that can act as nanowires carrying electric current. T4P are composed of a polymerized protein, pilin, and their assembly apparatuses share protein homologs with type II secretion systems in eubacteria and the flagella of archaea. T4P are found throughout Gram-negative bacterial families and have been studied most extensively in certain model Gram-negative species. Recently, it was discovered that T4P systems are also widespread among Gram-positive species, in particular the clostridia. Since Gram-positive and Gram-negative bacteria have many differences in cell wall architecture and other features, it is remarkable how similar the T4P core proteins are between these organisms, yet there are many key and interesting differences to be found as well. In this review, we compare the two T4P systems and identify and discuss the features they have in common and where they differ to provide a very broad-based view of T4P systems across all eubacterial species. PMID:24006467

  13. Disulfide-Bond-Forming Pathways in Gram-Positive Bacteria

    PubMed Central

    2015-01-01

    Disulfide bonds are important for the stability and function of many secreted proteins. In Gram-negative bacteria, these linkages are catalyzed by thiol-disulfide oxidoreductases (Dsb) in the periplasm. Protein oxidation has been well studied in these organisms, but it has not fully been explored in Gram-positive bacteria, which lack traditional periplasmic compartments. Recent bioinformatics analyses have suggested that the high-GC-content bacteria (i.e., actinobacteria) rely on disulfide-bond-forming pathways. In support of this, Dsb-like proteins have been identified in Mycobacterium tuberculosis, but their functions are not known. Actinomyces oris and Corynebacterium diphtheriae have recently emerged as models to study disulfide bond formation in actinobacteria. In both organisms, disulfide bonds are catalyzed by the membrane-bound oxidoreductase MdbA. Remarkably, unlike known Dsb proteins, MdbA is important for pathogenesis and growth, which makes it a potential target for new antibacterial drugs. This review will discuss disulfide-bond-forming pathways in bacteria, with a special focus on Gram-positive bacteria. PMID:26644434

  14. New antimicrobial approaches to gram positive respiratory infections.

    PubMed

    Liapikou, Adamantia; Cilloniz, Catia; Mensa, Josep; Torres, Antonio

    2015-06-01

    Nowadays, we face growing resistance among gram-positive and gram-negative pathogens that cause respiratory infection in the hospital and in the community. The spread of penicillin- and macrolide-resistant pneumococci, Community-acquired methicillin-resistant staphylococcus aureus (Ca-MRSA), the emergence of glycopeptide-resistant staphylococci underline the need for underline the need for therapeutic alternatives. A number of new therapeutic agents, with activity against the above Gram (+) respiratory pathogens, as ceftaroline, ceftopibrole, telavancin, tedizolid have become available, either in clinical trials or have been approved for clinical use. Especially, the development of new oral antibiotics, as nemonaxacin, omadacyclin, cethromycin and solithromycin will give a solution to the lack of oral drugs for outpatient treatment. In the future the clinician needs to optimize the use of old and new antibiotics to treat gram (+) respiratory serious infections. PMID:24878422

  15. Ribosomal DNA Sequencing for Identification of Aerobic Gram-Positive Rods in the Clinical Laboratory (an 18-Month Evaluation)

    PubMed Central

    Bosshard, P. P.; Abels, S.; Zbinden, R.; Böttger, E. C.; Altwegg, M.

    2003-01-01

    We have evaluated over a period of 18 months the use of 16S ribosomal DNA (rDNA) sequence analysis as a means of identifying aerobic gram-positive rods in the clinical laboratory. Two collections of strains were studied: (i) 37 clinical strains of gram-positive rods well identified by phenotypic tests, and (ii) 136 clinical isolates difficult to identify by standard microbiological investigations, i.e., identification at the species level was impossible. Results of molecular analyses were compared with those of conventional phenotypic identification procedures. Good overall agreement between phenotypic and molecular identification procedures was found for the collection of 37 clinical strains well identified by conventional means. For the 136 clinical strains which were difficult to identify by standard microbiological investigations, phenotypic characterization identified 71 of 136 (52.2%) isolates at the genus level; 65 of 136 (47.8%) isolates could not be discriminated at any taxonomic level. In comparison, 16S rDNA sequencing identified 89 of 136 (65.4%) isolates at the species level, 43 of 136 (31.6%) isolates at the genus level, and 4 of 136 (2.9%) isolates at the family level. We conclude that (i) rDNA sequencing is an effective means for the identification of aerobic gram-positive rods which are difficult to identify by conventional techniques, and (ii) molecular identification procedures are not required for isolates well identified by phenotypic investigations. PMID:12958237

  16. Photodynamic inactivation of Gram-positive bacteria employing natural resources.

    PubMed

    Mamone, L; Di Venosa, G; Gándara, L; Sáenz, D; Vallecorsa, P; Schickinger, S; Rossetti, M V; Batlle, A; Buzzola, F; Casas, A

    2014-04-01

    The aim of this paper was to investigate a collection of plant extracts from Argentina as a source of new natural photosensitizers (PS) to be used in Photodynamic Inactivation (PDI) of bacteria. A collection of plants were screened for phototoxicity upon the Gram-positive species Staphylococcus epidermidis. Three extracts turned out to be photoactive: Solanum verbascifolium flower, Tecoma stans flower and Cissus verticillata root. Upon exposure to a light dose of 55J/cm(2), they induced 4, 2 and 3logs decrease in bacterial survival, respectively. Photochemical characterisation of S. verbascifolium extract was carried out. PDI reaction was dependent mainly on singlet oxygen and to a lesser extent, on hydroxyl radicals, through type II and I reactions. Photodegradation experiments revealed that the active principle of the extract was not particularly photolabile. It is noticeable that S. verbascifolium -PDI was more efficient under sunlight as compared to artificial light (total eradication vs. 4 logs decrease upon 120min of sunlight). The balance between oxidant and antioxidant compounds is likely to be masking or unmasking potential PS of plant extracts, but employing the crude extract, the level of photoactivity of S. verbascifolium is similar to some artificial PS upon exposure to sunlight, demonstrating that natural resources can be employed in PDI of bacteria. PMID:24705374

  17. High-Level Fluorescence Labeling of Gram-Positive Pathogens

    PubMed Central

    Aymanns, Simone; Mauerer, Stefanie; van Zandbergen, Ger; Wolz, Christiane; Spellerberg, Barbara

    2011-01-01

    Fluorescence labeling of bacterial pathogens has a broad range of interesting applications including the observation of living bacteria within host cells. We constructed a novel vector based on the E. coli streptococcal shuttle plasmid pAT28 that can propagate in numerous bacterial species from different genera. The plasmid harbors a promoterless copy of the green fluorescent variant gene egfp under the control of the CAMP-factor gene (cfb) promoter of Streptococcus agalactiae and was designated pBSU101. Upon transfer of the plasmid into streptococci, the bacteria show a distinct and easily detectable fluorescence using a standard fluorescence microscope and quantification by FACS-analysis demonstrated values that were 10–50 times increased over the respective controls. To assess the suitability of the construct for high efficiency fluorescence labeling in different gram-positive pathogens, numerous species were transformed. We successfully labeled Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis, Enterococcus faecalis, Enterococcus faecium, Streptococcus mutans, Streptococcus anginosus and Staphylococcus aureus strains utilizing the EGFP reporter plasmid pBSU101. In all of these species the presence of the cfb promoter construct resulted in high-level EGFP expression that could be further increased by growing the streptococcal and enterococcal cultures under high oxygen conditions through continuous aeration. PMID:21731607

  18. Multidrug efflux pumps of Gram-positive bacteria.

    PubMed

    Schindler, Bryan D; Kaatz, Glenn W

    2016-07-01

    Gram-positive organisms are responsible for some of the most serious of human infections. Resistance to front-line antimicrobial agents can complicate otherwise curative therapy. These organisms possess multiple drug resistance mechanisms, with drug efflux being a significant contributing factor. Efflux proteins belonging to all five transporter families are involved, and frequently can transport multiple structurally unrelated compounds resulting in a multidrug resistance (MDR) phenotype. In addition to clinically relevant antimicrobial agents, MDR efflux proteins can transport environmental biocides and disinfectants which may allow persistence in the healthcare environment and subsequent acquisition by patients or staff. Intensive research on MDR efflux proteins and the regulation of expression of their genes is ongoing, providing some insight into the mechanisms of multidrug recognition and transport. Inhibitors of many of these proteins have been identified, including drugs currently being used for other indications. Structural modifications guided by structure-activity studies have resulted in the identification of potent compounds. However, lack of broad-spectrum pump inhibition combined with potential toxicity has hampered progress. Further work is required to gain a detailed understanding of the multidrug recognition process, followed by application of this knowledge in the design of safer and more highly potent inhibitors. PMID:27449594

  19. The acetylproteome of Gram-positive model bacterium Bacillus subtilis.

    PubMed

    Kim, Dooil; Yu, Byung Jo; Kim, Jung Ae; Lee, Yong-Jik; Choi, Soo-Geun; Kang, Sunghyun; Pan, Jae-Gu

    2013-05-01

    N(ε) -lysine acetylation, a reversible and highly regulated PTM, has been shown to occur in the model Gram-negative bacteria Escherichia coli and Salmonella enterica. Here, we extend this acetylproteome analysis to Bacillus subtilis, a model Gram-positive bacterium. Through anti-acetyllysine antibody-based immunoseparation of acetylpeptides followed by nano-HPLC/MS/MS analysis, we identified 332 unique lysine-acetylated sites on 185 proteins. These proteins are mainly involved in cellular housekeeping functions such as central metabolism and protein synthesis. Fifity-nine of the lysine-acetylated proteins showed homology with lysine-acetylated proteins previously identified in E. coli, suggesting that acetylated proteins are more conserved. Notably, acetylation was found at or near the active sites predicted by Prosite signature, including SdhA, RocA, Kbl, YwjH, and YfmT, indicating that lysine acetylation may affect their activities. In 2-amino-3-ketobutyrate CoA ligase Kbl, a class II aminotransferase, a lysine residue involved in pyridoxal phosphate attachment was found to be acetylated. This data set provides evidence for the generality of lysine acetylation in eubacteria and opens opportunities to explore the consequences of acetylation modification on the molecular physiology of B. subtilis. PMID:23468065

  20. Multifunctional cellulose beads and their interaction with gram positive bacteria.

    PubMed

    Blachechen, Leandro S; Fardim, Pedro; Petri, Denise F S

    2014-09-01

    Cellulose beads with ∼3 mm of diameter and high circularity were obtained by dripping cellulose solutions (5, 6, and 7 wt %) dissolved in NaOH7%/urea12%, into HCl 2 M coagulation bath. Carboxylic groups were generated on beads surface through NaClO/NaClO2/TEMPO oxidation method, achieving total charge density of ∼0.77 mmol/g. Pristine (CB) and oxidized (OCB) beads were characterized by means of optical images analyses, scanning electron microscopy (SEM) and compression tests. Both types of beads, CB and OCB, were used as adsorbent for poly(4-vinyl-N-pentylpyridinium) bromide, QPVP-C5, a bactericidal agent. The adsorption of QPVP-C5 on CB and OCB was evaluated by means of FTIR-ATR, UV-vis, CHN elemental analyses, and X-ray photoelectron spectroscopy (XPS). The adsorbed amount of QPVP-C5 was remarkably higher on OCB than on CB due to ionic interactions. Desorption was less than 5%. The interaction between neat OCB or OCB coated and two different amounts of QPVP-C5 and Gram-positive bacteria Micrococcus luteus was assessed by changes in turbidimetry, SEM, and elemental analyses. Bacteria adsorbed on the surface of neat OCB and weakly QPVP-C5 coated OCB due to hydrogen bonding or ion-dipole interaction. Notorious bactericidal action was observed for OCB samples coated with large amount of QPVP-C5. PMID:25100636

  1. Novel antimicrobial peptides that inhibit gram positive bacterial exotoxin synthesis.

    PubMed

    Merriman, Joseph A; Nemeth, Kimberly A; Schlievert, Patrick M

    2014-01-01

    Gram-positive bacteria, such as Staphylococcus aureus, cause serious human illnesses through combinations of surface virulence factors and secretion of exotoxins. Our prior studies using the protein synthesis inhibitor clindamycin and signal transduction inhibitors glycerol monolaurate and α-globin and β-globin chains of hemoglobin indicate that their abilities to inhibit exotoxin production by S. aureus are separable from abilities to inhibit growth of the organism. Additionally, our previous studies suggest that inhibition of exotoxin production, in absence of ability to kill S. aureus and normal flora lactobacilli, will prevent colonization by pathogenic S. aureus, while not interfering with lactobacilli colonization. These disparate activities may be important in development of novel anti-infective agents that do not alter normal flora. We initiated studies to explore the exotoxin-synthesis-inhibition activity of hemoglobin peptides further to develop potential agents to prevent S. aureus infections. We tested synthesized α-globin chain peptides, synthetic variants of α-globin chain peptides, and two human defensins for ability to inhibit exotoxin production without significantly inhibiting S. aureus growth. All of these peptides were weakly or not inhibitory to bacterial growth. However, the peptides were inhibitory to exotoxin production with increasing activity dependent on increasing numbers of positively-charged amino acids. Additionally, the peptides could be immobilized on agarose beads or have amino acid sequences scrambled and still retain exotoxin-synthesis-inhibition. The peptides are not toxic to human vaginal epithelial cells and do not inhibit growth of normal flora L. crispatus. These peptides may interfere with plasma membrane signal transduction in S. aureus due to their positive charges. PMID:24748386

  2. Antimicrobial susceptibility of gram-positive udder pathogens from bovine mastitis milk in Switzerland.

    PubMed

    Overesch, G; Stephan, R; Perreten, V

    2013-06-01

    We evaluated the susceptibility of the gram-positive mastitis pathogens S. aureus, Str. uberis, Str. dysgalactiae, E. faecalis and L. garviae to antibiotics that are of epidemiological interest or are critically important for mastitis therapy and human medicine. Penicillin resistance was found to be most frequent in S. aureus, and nearly 5 % of the Str. uberis strains displayed a decreased susceptibility to this antibiotic. Resistance to aminoglycosides and macrolides was also detected in the strains tested. The detection of methicillin-resistant S. aureus (MRSA) and of a ciprofloxacin-resistant Str. dysgalactiae isolate corroborated the emergence of mastitis pathogens resistant to critically important antibiotics and underscores the importance of susceptibility testing prior to antibiotic therapy. The monitoring of antibiotic susceptibility patterns and antibiogram analyses are strongly recommended for targeted antimicrobial treatment and to avoid the unnecessary use of the latest generation of antibiotics. PMID:23732380

  3. The bactericidal activities of HMR 3004, HMR 3647 and erythromycin against gram-positive bacilli and development of resistance.

    PubMed

    Fernández-Roblas, R; Calvo, R; Esteban, J; Bryskier, A; Soriano, F

    1999-02-01

    The bactericidal activities of two new ketolides, HMR 3004 and HMR 3647, and the potential to develop resistance to these two antibiotics were studied in Gram-positive bacilli. As judged by time-kill kinetics both ketolides were mostly bacteriostatic, being bactericidal against only highly susceptible isolates of Corynebacterium striatum (two isolates) and Corynebacterium minutissimum (one isolate). Spontaneous resistant mutants were detected in seven of 30 strains tested, mainly in Rhodococcus equi, C. minutissimum and C. striatum, with a very low frequency of mutation (10(-12)-10(-15)). PMID:11252337

  4. In Vitro Activities of Dalbavancin and Nine Comparator Agents against Anaerobic Gram-Positive Species and Corynebacteria

    PubMed Central

    Goldstein, Ellie J. C.; Citron, Diane M.; Merriam, C. Vreni; Warren, Yumi; Tyrrell, Kerin; Fernandez, Helen T.

    2003-01-01

    Dalbavancin is a novel semisynthetic glycopeptide with enhanced activity against gram-positive species. Its comparative in vitro activities and those of nine comparator agents, including daptomycin, vancomycin, linezolid, and quinupristin-dalfopristin, against 290 recent gram-positive clinical isolates strains, as determined by the NCCLS agar dilution method, were studied. The MICs of dalbavancin at which 90% of various isolates tested were inhibited were as follows: Actinomyces spp., 0.5 μg/ml; Clostridium clostridioforme, 8 μg/ml; C. difficile, 0.25 μg/ml; C. innocuum, 0.25 μg/ml; C. perfringens, 0.125 μg/ml; C. ramosum, 1 μg/ml; Eubacterium spp., 1 μg/ml; Lactobacillus spp., >32 μg/ml, Propionibacterium spp., 0.5 μg/ml; and Peptostreptococcus spp., 0.25 μg/ml. Dalbavancin was 1 to 3 dilutions more active than vancomycin against most strains. Dalbavancin exhibited excellent activity against gram-positive strains tested and warrants clinical evaluation. PMID:12760876

  5. Biochemical characterization of Gram-positive and Gram-negative plant-associated bacteria with micro-Raman spectroscopy.

    PubMed

    Paret, Mathews L; Sharma, Shiv K; Green, Lisa M; Alvarez, Anne M

    2010-04-01

    Raman spectra of Gram-positive and Gram-negative plant bacteria have been measured with micro-Raman spectrometers equipped with 785 and 514.5 nm lasers. The Gram-positive bacteria Microbacterium testaceum, Paenibacillus validus, and Clavibacter michiganensis subsp. michiganensis have strong carotenoid bands in the regions 1155-1157 cm(-1) and 1516-1522 cm(-1) that differentiate them from other tested Gram-negative bacteria. In the Raman spectrum of Gram-positive bacteria Bacillus megaterium excited with 785 nm laser, the Raman bands at 1157 and 1521 cm(-1) are weak in intensity compared to other Gram-positive bacteria, and these bands did not show significant resonance Raman enhancement in the spectrum recorded with 514.5 nm laser excitation. The Gram-positive bacteria could be separated from each other based on the bands associated with the in-phase C=C (v(1)) vibrations of the polyene chain of carotenoids. None of the Gram-negative bacteria tested had carotenoid bands. The bacteria in the genus Xanthomonas have a carotenoid-like pigment, xanthomonadin, identified in Xanthomonas axonopodis pv. dieffenbachiae, and it is a unique Raman marker for the bacteria. The representative bands for xanthomonadin were the C-C stretching (v(2)) vibrations of the polyene chain at 1135-1136 cm(-1) and the in-phase C=C (v(1)) vibrations of the polyene chain at 1529-1531 cm(-1), which were distinct from the carotenoid bands of other tested bacteria. The tyrosine peak in the region 1170-1175 cm(-1) was the only other marker present in Gram-negative bacteria that was absent in all tested Gram-positives. A strong-intensity exopolysaccharide-associated marker at 1551 cm(-1) is a distinguishable feature of Enterobacter cloacae. The Gram-negative Agrobacterium rhizogenes and Ralstonia solanacearum were differentiated from each other and other tested bacteria on the basis of presence or absence and relative intensities of peaks. The principal components analysis (PCA) of the spectra

  6. Cultivation of aerobic chemoorganotrophic proteobacteria and gram-positive bacteria from a hot spring microbial mat.

    PubMed Central

    Nold, S C; Kopczynski, E D; Ward, D M

    1996-01-01

    The diversity of aerobic chemoorganotrophic bacteria inhabiting the Octopus Spring cyanobacterial mat community (Yellowstone National Park) was examined by using serial-dilution enrichment culture and a variety of enrichment conditions to cultivate the numerically significant microbial populations. The most abundant bacterial populations cultivated from dilutions to extinction were obtained from enrichment flasks which contained 9.0 x 10(2) primary producer (Synechococcus spp.) cells in the inoculum. Two isolates exhibited 16S rRNA nucleotide sequences typical of beta-proteobacteria. One of these isolates contained a 16S rRNA sequence identical to a sequence type previously observed in the mat by molecular retrieval techniques. Both are distantly related to a new sequence directly retrieved from the mat and contributed by a beta-proteobacterial community member. Phenotypically diverse gram-positive isolates genetically similar to Bacillus flavothermus were obtained from a variety of dilutions and enrichment types. These isolates exhibited identical 16S rRNA nucleotide sequences through a variable region of the molecule. Of the three unique sequences observed, only one had been previously retrieved from the mat, illustrating both the inability of the cultivation methods to describe the composition of a microbial community and the limitations of the ability of molecular retrieval techniques to describe populations which may be less abundant in microbial communities. PMID:8899976

  7. Antimicrobial Diterpenes from Azorella Species Against Gram-Positive Bacteria.

    PubMed

    Donoso, Viviana; Bacho, Mitchell; Núiñez, Solange; Rovirosa, Juana; San-Martin, Aurelio; Leiva, Sergio

    2015-11-01

    The present study was aimed at evaluating the antibacterial activity of mulinane and azorellane diterpenes isolated from the Andean plants Azorella compacta and A. trifoliolata and semisynthetic derivatives against reference and multidrug-resistant strains. The results revealed that the semisynthetic compound 7-acetoxy-mulin-9,12-diene (5) exhibited antibacterial activity against reference and multidrug-resistant strains of Staphylococcus aureus and moderate antimycobacterial activity against Mycobacterium smegmatis ATCC 14468. PMID:26749825

  8. Multistep Resistance Development Studies of Ceftaroline in Gram-Positive and -Negative Bacteria▿

    PubMed Central

    Clark, Catherine; McGhee, Pamela; Appelbaum, Peter C.; Kosowska-Shick, Klaudia

    2011-01-01

    Ceftaroline, the active component of the prodrug ceftaroline fosamil, is a novel broad-spectrum cephalosporin with bactericidal activity against Gram-positive and -negative isolates. This study evaluated the potential for ceftaroline and comparator antibiotics to select for clones of Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis with elevated MICs. S. pneumoniae and S. pyogenes isolates in the present study were highly susceptible to ceftaroline (MIC range, 0.004 to 0.25 μg/ml). No streptococcal strains yielded ceftaroline clones with increased MICs (defined as an increase in MIC of >4-fold) after 50 daily passages. Ceftaroline MICs for H. influenzae and M. catarrhalis were 0.06 to 2 μg/ml for four strains and 8 μg/ml for a β-lactamase-positive, efflux-positive H. influenzae with a mutation in L22. One H. influenzae clone with an increased ceftaroline MIC (quinolone-resistant, β-lactamase-positive) was recovered after 20 days. The ceftaroline MIC for this isolate increased 16-fold, from 0.06 to 1 μg/ml. MICs for S. aureus ranged from 0.25 to 1 μg/ml. No S. aureus isolates tested with ceftaroline had clones with increased MIC (>4-fold) after 50 passages. Two E. faecalis isolates tested had ceftaroline MICs increased from 1 to 8 μg/ml after 38 days and from 4 to 32 μg/ml after 41 days, respectively. The parental ceftaroline MIC for the one K. pneumoniae extended-spectrum β-lactamase-negative isolate tested was 0.5 μg/ml and did not change after 50 daily passages. PMID:21343467

  9. Antibacterial Efficacy of Eravacycline In Vivo against Gram-Positive and Gram-Negative Organisms.

    PubMed

    Monogue, Marguerite L; Thabit, Abrar K; Hamada, Yukihiro; Nicolau, David P

    2016-08-01

    Members of the tetracycline class are frequently classified as bacteriostatic. However, recent findings have demonstrated an improved antibacterial killing profile, often achieving ≥3 log10 bacterial count reduction, when such antibiotics have been given for periods longer than 24 h. We aimed to study this effect with eravacycline, a novel fluorocycline, given in an immunocompetent murine thigh infection model over 72 h against two methicillin-resistant Staphylococcus aureus (MRSA) isolates (eravacycline MICs = 0.03 and 0.25 μg/ml) and three Enterobacteriaceae isolates (eravacycline MICs = 0.125 to 0.25 μg/ml). A humanized eravacycline regimen, 2.5 mg/kg of body weight given intravenously (i.v.) every 12 h (q12h), demonstrated progressively enhanced activity over the 72-h study period. A cumulative dose response in which bacterial density was reduced by more than 3 log10 CFU at 72 h was noted over the study period in the two Gram-positive isolates, and eravacycline performed similarly to comparator antibiotics (tigecycline, linezolid, and vancomycin). A cumulative dose response with eravacycline and comparators (tigecycline and meropenem) over the study period was also observed in the Gram-negative isolates, although more variability in bacterial killing was observed for all antibacterial agents. Overall, a bacterial count reduction of ≥3 log was achieved in one of the three isolates with both eravacycline and tigecycline, while meropenem achieved a similar endpoint against two of the three isolates. Bactericidal activity is typically defined in vitro over 24 h; however, extended regimen studies in vivo may demonstrate an improved correlation with clinical outcomes by better identification of antimicrobial effects. PMID:27353265

  10. Thermophilic Gram-Positive Biocatalysts for Biomass Conversion to Ethanol

    SciTech Connect

    Shanmugam, K.T.; Ingram, L.O.; Maupin-Furlow, J.A.; Preston, J.F.; Aldrich, H.C.

    2003-12-01

    Production of energy from renewable sources is receiving increased attention due to the finite nature of fossil fuels and the environmental impact associated with the continued large scale use of fossil energy sources. Biomass, a CO2-neutral abundant resource, is an attractive alternate source of energy. Biomass-derived sugars, such as glucose, xylose, and other minor sugars, can be readily fermented to fuel ethanol and commodity chemicals. Extracellular cellulases produced by fungi are commercially developed for depolymerization of cellulose in biomass to glucose for fermentation by appropriate biocatalysts in a simultaneous saccharification and fermentation (SSF) process. Due to the differences in the optimum conditions for the activity of the fungal cellulases and the growth and fermentation characteristics of the current industrial biocatalysts, SSF of cellulose is envisioned at conditions that are not optimal for the fungal cellulase activity leading to higher than required cost of cellulase in SSF. We have isolated bacterial biocatalysts whose growth and fermentation requirements match the optimum conditions for commercial fungal cellulase activity (pH 5.0 and 50 deg. C). These isolates fermented both glucose and xylose, major components of cellulose and hemicellulose, respectively, to L(+)-lactic acid. Xylose was metabolized through the pentose-phosphate pathway by these organisms as evidenced by the fermentation profile and analysis of the fermentation products of 13C1-xylose by NMR. As expected for the metabolism of xylose by the pentose-phosphate pathway, 13C-lactate accounted for more than 90% of the total 13C-labeled products. All three strains fermented crystalline cellulose to lactic acid with the addition of fungal cellulase (Spezyme CE) (SSF) at an optimum of about 10 FPU/g cellulose. These isolates also fermented cellulose and sugar cane bagasse hemicellulose acid hydrolysate simultaneously. Based on fatty acid profile and 16S rRNA sequence, these

  11. Robenidine Analogues as Gram-Positive Antibacterial Agents.

    PubMed

    Abraham, Rebecca J; Stevens, Andrew J; Young, Kelly A; Russell, Cecilia; Qvist, Anastasia; Khazandi, Manouchehr; Wong, Hui San; Abraham, Sam; Ogunniyi, Abiodun D; Page, Stephen W; O'Handley, Ryan; McCluskey, Adam; Trott, Darren J

    2016-03-10

    Robenidine, 1 (2,2'-bis[(4-chlorophenyl)methylene]carbonimidic dihydrazide), was active against MRSA and VRE with MIC's of 8.1 and 4.7 μM, respectively. SAR revealed tolerance for 4-Cl isosteres with 4-F (8), 3-F (9), 3-CH3 (22), and 4-C(CH3)3 (27) (23.7-71 μM) and with 3-Cl (3), 4-CH3 (21), and 4-CH(CH3)2 (26) (8.1-13.0 μM). Imine carbon alkylation identified a methyl/ethyl binding pocket that also accommodated a CH2OH moiety (75; 2,2'-bis[1-(4-chlorophenyl)-2-hydroxyethylidene]carbonimidic dihydrazide). Analogues 1, 27 (2,2'-bis{[4-(1,1-dimethylethyl)phenyl]methylene}carbonimidic dihydrazide), and 69 (2,2'-bis[1-(4-chlorophenyl)ethylidene]carbonimidic dihydrazide hydrochloride) were active against 24 clinical MRSA and MSSA isolates. No dose-limiting cytotoxicity at ≥2× MIC or hemolysis at ≥8× MIC was observed. Polymyxin B addition engendered Escherichia coli and Pseudomonas aeruginosa Gram-negative activity MIC's of 4.2-21.6 μM. 1 and 75 displayed excellent microsomal stability, intrinsic clearance, and hepatic extraction ratios with T1/2 > 247 min, CLint < 7 μL/min/mg protein, and EH < 0.22 in both human and mouse liposomes for 1 and in human liposomes for 75. PMID:26765953

  12. Uncultivated Magnetotactic Cocci from Yuandadu Park in Beijing, China▿

    PubMed Central

    Lin, Wei; Pan, Yongxin

    2009-01-01

    In the present study, we investigated a group of uncultivated magnetotactic cocci, which was magnetically isolated from a freshwater pond in Beijing, China. Light and transmission electron microscopy showed that these cocci ranged from 1.5 to 2.5 μm and contained two to four chains of magnetite magnetosomes, which sometimes were partially disorganized. Overall, the size of the disorganized magnetosomes was significantly smaller than that arranged in chains. All characterized magnetosome crystals were elongated (shape factor = 0.64) and fall into the single-domain size range (30 to 115 nm). Comparative 16S rRNA gene sequence analysis and fluorescence in situ hybridization showed that the enriched bacteria were a virtually homogeneous population and represented a novel lineage in the Alphaproteobacteria. The closest cultivated relative was magnetotactic coccoid strain MC-1 (88% sequence identity). First-order reversal curve diagrams revealed that these cocci had relatively strong magnetic interactions compared to the single-chain magnetotactic bacteria. Low-temperature magnetic measurements showed that the Verwey transition of them was ∼108 K, confirming magnetite magnetosomes, and the delta ratio δFC/δZFC was >2. Based on the structure, phylogenetic position and magnetic properties, the enriched magnetotactic cocci of Alphaproteobacteria are provisionally named as “Candidatus Magnetococcus yuandaducum.” PMID:19376904

  13. The affect of low-coherent light on microbial colony forming ability and morphology of some gram-positive and gram-negative bacteria

    NASA Astrophysics Data System (ADS)

    Popov, Denis E.; Tuchina, Elena S.; Chernova, Julia A.; Podshibyakin, Dmitry; Rudik, Dmitry V.; Samsonova, Maria; Gromov, Igor; Tuchin, Valery V.

    2005-06-01

    Gram-negative E. coli, gram-positive facultative anaerobe cocci Staphylococcus lugdensis, Micrococcus halobius, and Stomatococcus mucilaginosus as subjects of study were chosen. LEDs with spectrum maxima at 405 nm (without any exogenous sensitizer) and 660 nm (in conjunction with methylene blue) and power densities of 23 mW/cm2 and 5.7 mW/cm2 accordingly as continuous light sources were chosen. Photosensitized light's affect by methylene blue was studied on E. coli only. The original scheme of experiment set up was developed. It permits one to increase expositions quantity in each experiment for more certain trend's construction over dose curves and decrease parasite flora sowing. As a result of accomplished studies it was established that blue low-coherent light have unalike weak light's dose depending suppressing effect on cocci whereas red low-coherent light have a moderate dose-depended suppressing effect at low irradiation doses and a moderate dose-depended stimulating effect at high irradiation doses on sensitized by MeBlue E. coli. For all ofthis, but Staphylococcus morphology changes were observed.

  14. Can procalcitonin differentiate Staphylococcus aureus from coagulase-negative staphylococci in clustered gram-positive bacteremia?

    PubMed

    Shomali, William; Hachem, Ray; Chaftari, Anne-Marie; Bahu, Ramez; Helou, Gilbert El; Jiang, Ying; Hanania, Alex; Reitzel, Ruth; Raad, Issam

    2013-06-01

    Procalcitonin (PCT) and pro-adrenomedullin (ProADM) have been proposed as diagnostic and prognostic biomarkers of infection. Between July 2009 and January 2012, we studied the role of these biomarkers in 163 patients with clustered gram-positive and gram-negative bacteremia. PCT levels were significantly higher in patients with Staphylococcus aureus and gram-negative bacteremia than those with coagulase-negative staphylococci (CoNS) isolated from blood cultures (P = 0.29 and <0.001, respectively). ProADM levels were only significantly higher in patients with gram-negative bacteremia (median 1.46 nmol/L) than those with CoNS (median 1.01 nmol/L) (P = 0.04). Among patients with CoNS, PCT, and ProADM, levels failed to differentiate blood contamination (medians 0.24 ng/mL and 0.97 nmol/L) from true bacteremia (medians 0.26 ng/mL and 1.14 nmol/L) (P = 0.51 and 0.57, respectively). In cancer patients, PCT (and to a lesser extent, ProADM) was useful in differentiating CoNS from S. aureus and gram-negative bacteremia. PMID:23578976

  15. [Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between april 2003 and march 2004].

    PubMed

    Shinagawa, Nagao; Fuchimoto, Sadayoshi; Sueda, Taijiro; Hiyama, Eizo; Takesue, Yoshio; Murakami, Yoshiaki; Ooge, Hiroki; Uemura, Kenichiro; Mizuno, Isamu; Tsumura, Hiroaki; Hirata, Koichi; Katsuramaki, Tadashi; Mizukuchi, Tohru; Ushijima, Yasuhide; Ushida, Tomohiro; Aikawa, Naoki; Yo, Kikuo; Takayama, Tadatoshi; Sato, Takeshi; Kato, Koumei; Yura, Jiro; Manabe, Tadao; Takeyama, Hiromitsu; Wakasugi, Takehiro; Taniguchi, Masaaki; Yokoyama, Takashi; Takeuchi, Hitoshi; Yasui, Yoshimasa; Mashita, Keiji; Ikeda, Seiyo; Yasunami, Yoichi; Ryu, Shinichiro; Ishikawa, Syu; Mizuno, Akira; Kubo, Shoji; Suehiro, Shigefumi; Fujimoto, Mikio; Higaki, Kazuyuki; Tanimura, Hiroshi; Taniguchi, Katsutoshi; Tsuji, Takeshi; Ohnishi, Hironobu; Yamaue, Hiroki; Kawai, Manabu; Tanaka, Noriaki; Iwagaki, Hiromi; Kimura, Hideyuki

    2007-04-01

    Tendency of isolated bacteria from infections in abdominal surgery during the period from April 2005 to March 2006 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 384 strains including 18 strains of Candida spp. were isolated from 161 (70.3%) of 229 patients with surgical infections. One hundred and ninty-five strains were isolated from primary infections, and 171 strains were isolated from postoperative infections. From primary infections, aerobic Gram-negative bacteria and aerobic Gram-positive bacteria were predominant, while aerobic Gram-positive bacteria were predominant from postoperative infections. The isolation rate of aerobic Gram-positive bacteria, such as Enterococcus spp. and Staphylococcus aureus were higher from both types of infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Pseudomonas aeruginosa, Klebsiella spp. in this order, and from postoperative infections, E. coli was the most predominantly isolated, followed by Klebsiella pneumoniae and P. aeruginosa. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both primary and postoperative infections. In this series, we noticed no vancomycin-resistant Gram-positive cocci, nor multidrug-resistant P. aeruginosa. But cefazolin-resistant E. coli producing extended spectrum fl-lactamase was seen in 5.0 per cents. We should be carefully followed up the facts that the increasing isolation rates of B. fragilis group and Bilophila wadsworthia which were resistant to both penicillins and cephems. PMID:17612256

  16. Performances of VITEK 2 Colorimetric Cards for Identification of Gram-Positive and Gram-Negative Bacteria

    PubMed Central

    Wallet, Frédéric; Loïez, Caroline; Renaux, Emilie; Lemaitre, Nadine; Courcol, René J.

    2005-01-01

    Thepurpose of this study was to evaluate the new VITEK 2 identification cards that use colorimetric reading to identify gram-positive and gram-negative bacteria (GP and GN cards, respectively) in comparison to fluorimetric cards (ID-GPC and ID-GNB, respectively). A total of 580 clinical isolates and stock collection strains belonging to 116 taxa were included in the study. Of the 249 gram-positive strains tested with both the ID-GPC and GP cards, 218 (87.5%) and 235 (94.4%) strains were correctly identified (to the genus and species level), respectively. Of the 331 gram-negative strains tested with the ID-GNB and GN cards, 295 (89.1%) and 321 (97%) strains were correctly identified, respectively. Another focus of the study was to apply the percentages of correct identifications obtained in this study to the list of bacteria isolated in our laboratory (32,739 isolates) in the year 2004. We obtained 97.9% correct identifications with the colorimetric cards and 93.9% with fluorescent cards. PMID:16145083

  17. Clinical update on linezolid in the treatment of Gram-positive bacterial infections

    PubMed Central

    Ager, Sally; Gould, Kate

    2012-01-01

    Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs. PMID:22787406

  18. Thusin, a Novel Two-Component Lantibiotic with Potent Antimicrobial Activity against Several Gram-Positive Pathogens

    PubMed Central

    Xin, Bingyue; Zheng, Jinshui; Liu, Hualin; Li, Junhua; Ruan, Lifang; Peng, Donghai; Sajid, Muhammad; Sun, Ming

    2016-01-01

    Due to the rapidly increasing prevalence of multidrug-resistant bacterial strains, the need for new antimicrobial drugs to treat infections has become urgent. Bacteriocins, which are antimicrobial peptides of bacterial origin, are considered potential alternatives to conventional antibiotics and have attracted widespread attention in recent years. Among these bacteriocins, lantibiotics, especially two-component lantibiotics, exhibit potent antimicrobial activity against some clinically relevant Gram-positive pathogens and have potential applications in the pharmaceutical industry. In this study, we characterized a novel two-component lantibiotic termed thusin that consists of Thsα, Thsβ, and Thsβ' (mutation of Thsβ, A14G) and that was isolated from a B. thuringiensis strain BGSC 4BT1. Thsα and Thsβ (or Thsβ') exhibit optimal antimicrobial activity at a 1:1 ratio and act sequentially to affect target cells, and they are all highly thermostable (100°C for 30 min) and pH tolerant (pH 2.0 to 9.0). Thusin shows remarkable efficacy against all tested Gram-positive bacteria and greater activities than two known lantibiotics thuricin 4A-4 and ticin A4, and one antibiotic vancomycin against various bacterial pathogens (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus (MRSA), Staphylococcus sciuri, Enterococcus faecalis, and Streptococcus pneumoniae). Moreover, thusin is also able to inhibit the outgrowth of B. cereus spores. The potent antimicrobial activity of thusin against some Gram-positive pathogens indicates that it has potential for the development of new drugs. PMID:27486447

  19. Thusin, a Novel Two-Component Lantibiotic with Potent Antimicrobial Activity against Several Gram-Positive Pathogens.

    PubMed

    Xin, Bingyue; Zheng, Jinshui; Liu, Hualin; Li, Junhua; Ruan, Lifang; Peng, Donghai; Sajid, Muhammad; Sun, Ming

    2016-01-01

    Due to the rapidly increasing prevalence of multidrug-resistant bacterial strains, the need for new antimicrobial drugs to treat infections has become urgent. Bacteriocins, which are antimicrobial peptides of bacterial origin, are considered potential alternatives to conventional antibiotics and have attracted widespread attention in recent years. Among these bacteriocins, lantibiotics, especially two-component lantibiotics, exhibit potent antimicrobial activity against some clinically relevant Gram-positive pathogens and have potential applications in the pharmaceutical industry. In this study, we characterized a novel two-component lantibiotic termed thusin that consists of Thsα, Thsβ, and Thsβ' (mutation of Thsβ, A14G) and that was isolated from a B. thuringiensis strain BGSC 4BT1. Thsα and Thsβ (or Thsβ') exhibit optimal antimicrobial activity at a 1:1 ratio and act sequentially to affect target cells, and they are all highly thermostable (100°C for 30 min) and pH tolerant (pH 2.0 to 9.0). Thusin shows remarkable efficacy against all tested Gram-positive bacteria and greater activities than two known lantibiotics thuricin 4A-4 and ticin A4, and one antibiotic vancomycin against various bacterial pathogens (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus (MRSA), Staphylococcus sciuri, Enterococcus faecalis, and Streptococcus pneumoniae). Moreover, thusin is also able to inhibit the outgrowth of B. cereus spores. The potent antimicrobial activity of thusin against some Gram-positive pathogens indicates that it has potential for the development of new drugs. PMID:27486447

  20. Mechanism of action of recombinant acc-royalisin from royal jelly of Asian honeybee against gram-positive bacteria.

    PubMed

    Shen, Lirong; Liu, Dandan; Li, Meilu; Jin, Feng; Din, Meihui; Parnell, Laurence D; Lai, Chao-Qiang

    2012-01-01

    The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees, has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Asian honeybee Apis cerana cerana, was expressed by fusing with glutathione S-transferase (GST) in Escherichia coli BL21, isolated and purified. The agar dilution assays with inhibition zone showed that RAcc-royalisin, similar to nisin, inhibits the growth of Gram-positive bacteria. The antibacterial activity of RAcc-royalisin was associated with its concentration, and was weakened by heat treatment ranging from 55°C to 85°C for 15 min. Both RAcc-royalisin and nisin exhibited the minimum inhibitory concentrations (MIC) of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml against Gram-positive bacterial strains, Bacillus subtilis and Micrococcus flavus and Staphyloccocus aureus in the microplate assay, respectively. However, RAcc-royalisin did not show antimicrobial activity against tested Gram-negative bacterial and fungal strains. The antibacterial activity of RAcc-royalisin agrees well with the decrease in bacterial cell hydrophobicity, the leakage of 260-nm absorbing materials, and the observation by transmission electron microscopy, all indicating that RAcc-royalisin induced the disruption and dysfunction of cell walls and membranes. This is the first report detailing the antibacterial mechanism of royalisin against Gram-positive bacteria, and provides insight into the application of recombinant royalisin in food and pharmaceutical industries as an antimicrobial agent. PMID:23056609

  1. Surface multiheme c-type cytochromes from Thermincola potens and implications for respiratory metal reduction by Gram-positive bacteria

    PubMed Central

    Carlson, Hans K.; Iavarone, Anthony T.; Gorur, Amita; Yeo, Boon Siang; Tran, Rosalie; Melnyk, Ryan A.; Mathies, Richard A.; Auer, Manfred; Coates, John D.

    2012-01-01

    Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium. PMID:22307634

  2. Nucleotide sequence alignment of hdcA from Gram-positive bacteria.

    PubMed

    Diaz, Maria; Ladero, Victor; Redruello, Begoña; Sanchez-Llana, Esther; Del Rio, Beatriz; Fernandez, Maria; Martin, Maria Cruz; Alvarez, Miguel A

    2016-03-01

    The decarboxylation of histidine -carried out mainly by some gram-positive bacteria- yields the toxic dietary biogenic amine histamine (Ladero et al. 2010 〈10.2174/157340110791233256〉 [1], Linares et al. 2016 〈http://dx.doi.org/10.1016/j.foodchem.2015.11.013〉〉 [2]). The reaction is catalyzed by a pyruvoyl-dependent histidine decarboxylase (Linares et al. 2011 〈10.1080/10408398.2011.582813〉 [3]), which is encoded by the gene hdcA. In order to locate conserved regions in the hdcA gene of Gram-positive bacteria, this article provides a nucleotide sequence alignment of all the hdcA sequences from Gram-positive bacteria present in databases. For further utility and discussion, see 〈http://dx.doi.org/ 10.1016/j.foodcont.2015.11.035〉〉 [4]. PMID:26958625

  3. Labeling and Selective Inactivation of Gram-Positive Bacteria Employing Bimodal Photoprobes with Dual Readouts.

    PubMed

    Galstyan, Anzhela; Block, Desiree; Niemann, Silke; Grüner, Malte C; Abbruzzetti, Stefania; Oneto, Michele; Daniliuc, Constantin G; Hermann, Sven; Viappiani, Cristiano; Schäfers, Michael; Löffler, Bettina; Strassert, Cristian A; Faust, Andreas

    2016-04-01

    Carbohydrate-conjugated silicon(IV) phthalocyanines with bimodal photoactivity were developed as probes with both fluorescent labeling and photosensitizing capabilities, and the concomitant fluorescent labeling and photoinduced inactivation of Gram-positive and Gram-negative models was explored. The maltohexaose-conjugated photoprobe provides a dual readout to distinguish between both groups of pathogens, as only the Gram-positive species was inactivated, even though both appeared labeled with near-infrared luminescence. Antibiotic resistance did not hinder the phototoxic effect, as even the methicillin-resistant pathogen Staphylococcus aureus (MRSA) was completely photoinactivated. Time-resolved confocal fluorescence microscopy analysis suggests that the photoprobe sticks onto the outer rim of the microorganisms, explaining the resistance of Gram-negative species on the basis of their membrane constitution. The mannose-conjugated photoprobe yields a different readout because it is able to label and to inactivate only the Gram-positive strain. PMID:26929124

  4. New insights into regulation of the tryptophan biosynthetic operon in Gram-positive bacteria.

    PubMed

    Gutierrez-Preciado, A; Jensen, R A; Yanofsky, C; Merino, E

    2005-08-01

    The tryptophan operon of Bacillus subtilis serves as an excellent model for investigating transcription regulation in Gram-positive bacteria. In this article, we extend this knowledge by analyzing the predicted regulatory regions in the trp operons of other fully sequenced Gram-positive bacteria. Interestingly, it appears that in eight of the organisms examined, transcription of the trp operon appears to be regulated by tandem T-box elements. These regulatory elements have recently been described in the trp operons of two bacterial species. Single T-box elements are commonly found in Gram-positive bacteria in operons encoding aminoacyl tRNA synthetases and proteins performing other functions. Different regulatory mechanisms appear to be associated with variations of trp gene organization within the trp operon. PMID:15953653

  5. Class D β-lactamases do exist in Gram-positive bacteria

    SciTech Connect

    Toth, Marta; Antunes, Nuno Tiago; Stewart, Nichole K.; Frase, Hilary; Bhattacharya, Monolekha; Smith, Clyde A.; Vakulenko, Sergei B.

    2015-11-09

    Production of β-lactamases of one of four molecular classes (A, B, C and D) is the major mechanism of bacterial resistance to β-lactams, the largest class of antibiotics, which have saved countless lives since their inception 70 years ago. Although several hundred efficient class D enzymes have been identified in Gram-negative pathogens over the last four decades, none have been reported in Gram-positive bacteria. Here we demonstrate that efficient class D β-lactamases capable of hydrolyzing a wide array of β-lactam substrates are widely disseminated in various species of environmental Gram-positive organisms. Class D enzymes of Gram-positive bacteria have a distinct structural architecture and employ a unique substrate-binding mode that is quite different from that of all currently known class A, C and D β-lactamases. In conclusion, these enzymes thus constitute a previously unknown reservoir of novel antibiotic-resistance enzymes.

  6. Nucleotide sequence alignment of hdcA from Gram-positive bacteria

    PubMed Central

    Diaz, Maria; Ladero, Victor; Redruello, Begoña; Sanchez-Llana, Esther; del Rio, Beatriz; Fernandez, Maria; Martin, Maria Cruz; Alvarez, Miguel A.

    2016-01-01

    The decarboxylation of histidine -carried out mainly by some gram-positive bacteria- yields the toxic dietary biogenic amine histamine (Ladero et al. 2010 〈10.2174/157340110791233256〉 [1], Linares et al. 2016 〈http://dx.doi.org/10.1016/j.foodchem.2015.11.013〉〉 [2]). The reaction is catalyzed by a pyruvoyl-dependent histidine decarboxylase (Linares et al. 2011 〈10.1080/10408398.2011.582813〉 [3]), which is encoded by the gene hdcA. In order to locate conserved regions in the hdcA gene of Gram-positive bacteria, this article provides a nucleotide sequence alignment of all the hdcA sequences from Gram-positive bacteria present in databases. For further utility and discussion, see 〈http://dx.doi.org/ 10.1016/j.foodcont.2015.11.035〉〉 [4]. PMID:26958625

  7. Class D β-lactamases do exist in Gram-positive bacteria

    PubMed Central

    Toth, Marta; Antunes, Nuno Tiago; Stewart, Nichole K.; Frase, Hilary; Bhattacharya, Monolekha; Smith, Clyde; Vakulenko, Sergei

    2015-01-01

    Production of β-lactamases of the four molecular classes (A, B, C, and D) is the major mechanism of bacterial resistance to β-lactams, the largest class of antibiotics that have saved countless lives since their inception 70 years ago. Although several hundred efficient class D enzymes have been identified in Gram-negative pathogens over the last four decades, they have not been reported in Gram-positive bacteria. Here we demonstrate that efficient class D β-lactamases capable of hydrolyzing a wide array of β-lactam substrates are widely disseminated in various species of environmental Gram-positive organisms. Class D enzymes of Gram-positive bacteria have a distinct structural architecture and employ a unique substrate binding mode quite different from that of all currently known class A, C, and D β-lactamases. They constitute a novel reservoir of antibiotic resistance enzymes. PMID:26551395

  8. Stabilizing isopeptide bonds revealed in gram-positive bacterial pilus structure.

    PubMed

    Kang, Hae Joo; Coulibaly, Fasséli; Clow, Fiona; Proft, Thomas; Baker, Edward N

    2007-12-01

    Many bacterial pathogens have long, slender pili through which they adhere to host cells. The crystal structure of the major pilin subunit from the Gram-positive human pathogen Streptococcus pyogenes at 2.2 angstroms resolution reveals an extended structure comprising two all-beta domains. The molecules associate in columns through the crystal, with each carboxyl terminus adjacent to a conserved lysine of the next molecule. This lysine forms the isopeptide bonds that link the subunits in native pili, validating the relevance of the crystal assembly. Each subunit contains two lysine-asparagine isopeptide bonds generated by an intramolecular reaction, and we find evidence for similar isopeptide bonds in other cell surface proteins of Gram-positive bacteria. The present structure explains the strength and stability of such Gram-positive pili and could facilitate vaccine development. PMID:18063798

  9. Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

    2010-02-01

    A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO2-NH2-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

  10. Use of PNA FISH for blood cultures growing Gram-positive cocci in chains without a concomitant antibiotic stewardship intervention does not improve time to appropriate antibiotic therapy.

    PubMed

    Cosgrove, Sara E; Li, David X; Tamma, Pranita D; Avdic, Edina; Hadhazy, Eric; Wakefield, Teresa; Gherna, Michael; Carroll, Karen C

    2016-09-01

    Peptide nucleic acid fluorescence in situ hybridization (PNA FISH) is a rapid diagnostic assay that can identify certain organisms growing in blood cultures 30-90 min from the time of positive Gram-stain. Existing studies have demonstrated a clinical utility with this assay when antibiotic stewardship programs assist clinicians with interpreting the results. However, the benefit of these rapid assays in the absence of concomitant antibiotic stewardship involvement is unclear. In this randomized study of 220 patients with enterococcal or streptococcal bacteremia, we found that PNA FISH, in the absence of concomitant input from an antibiotic stewardship program, had no impact on time to effective or optimal therapy, length of hospital stay, or in-hospital mortality. Our results suggest that in the absence of guidance from an antibiotic stewardship program, the clinical benefits of rapid diagnostic microbiological tools may be reduced. PMID:27412814

  11. Isoelectric points and surface hydrophobicity of Gram-positive cocci as determined by cross-partition and hydrophobic affinity partition in aqueous two-phase systems.

    PubMed Central

    Miörner, H; Albertsson, P A; Kronvall, G

    1982-01-01

    Thirty-nine streptococcal strains belonging to groups A, C, and G and 12 staphylococcal strains were investigated with respect to surface charge and hydrophobicity. Isoelectric points of the bacteria were determined by cross-partition experiments in dextran-polyethylene glycol two-phase systems containing charged polymers. The results obtained indicate that group A, C, and G streptococci have isoelectric points of pH 3.75 +/- 0.15 standard deviation. Staphylococci show an isoelectric point of around pH 2 and thereby differ markedly from the streptococci. Pretreatment of bacteria with human serum resulted in a significant change in the isoelectric points of streptococci. In a second series of experiments, an aqueous dextran-polyethylene glycol two-phase system containing polyethylene glycol palmitate or stearate was used to study the hydrophobic surface properties of the bacterial cells. The partition of the staphylococci was not influenced by the addition of up to 1% (wt/wt) polyethylene glycol palmitate or stearate, whereas the streptococci showed a large variation in affinity for polyethylene glycol-bound hydrophobic groups. The bacterial strains included in the study were also tested for uptake of human serum proteins. A positive correlation was found between the hydrophobic affinity of group A streptococci and the density of receptors for aggregated beta-2-microglobulin. PMID:7042571

  12. The use of lysozyme modified with fluorescein for the detection of Gram-positive bacteria.

    PubMed

    Arabski, Michał; Konieczna, Iwona; Tusińska, Ewa; Wąsik, Sławomir; Relich, Inga; Zając, Krzysztof; Kamiński, Zbigniew J; Kaca, Wiesław

    2015-01-01

    Lysozyme (1,4-β-N-acetylmuramidase) is commonly applied in the food, medical, and pharmaceutical industries. In this study, we tested a novel application of fluorescein-modified lysozyme (using carboxyfluorescein with a triazine-based coupling reagent) as a new tool for the detection of Gram-positive soil bacteria. The results, obtained by cultivation methods, fluorescence analysis, and laser interferometry, showed that, after optimization, fluorescein-modified lysozyme could be used to evaluate the prevalence of Gram-positive bacteria essential in bioremediation of soils with low pH, such as those degraded by sulfur. PMID:24916601

  13. Pharmacologic options for CNS infections caused by resistant Gram-positive organisms.

    PubMed

    Peppard, William J; Johnston, Carolyn J; Urmanski, Angela M

    2008-02-01

    Infectious disease continues to evolve, presenting new and challenging clinical situations for practitioners. Specific to device-related and neurosurgical-related CNS infections, Gram-positive organisms are of growing concern. Current Infection Disease Society of America guidelines for the treatment of CNS infections offer little direction after conventional therapy, consisting of vancomycin, has failed or the patient has demonstrated intolerance. A review of literature evaluating alternative therapies, specifically linezolid, quinupristin/dalfopristin, daptomycin and tigecycline, will be presented. Interpretations of these data are offered followed by a brief presentation of future therapies, including ortavancin, telavancin, dalbavancin, ceftobiprole and iclaprim, all of which possess potent Gram-positive activity. PMID:18251666

  14. Predictive Factors of Spontaneous Bacterial Peritonitis Caused by Gram-Positive Bacteria in Patients With Cirrhosis

    PubMed Central

    Kim, Jung Ho; Jeon, Yong Duk; Jung, In Young; Ahn, Mi Young; Ahn, Hea Won; Ahn, Jin Young; Ku, Nam Su; Han, Sang Hoon; Choi, Jun Yong; Ahn, Sang Hoon; Song, Young Goo; Han, Kwang Hyub; Kim, June Myung

    2016-01-01

    Abstract Spontaneous bacterial peritonitis (SBP) in patients with cirrhosis is typically caused by gram-negative bacteria. However, the number of SBP cases due to gram-positive bacteria is steadily increasing. To date, little is known about the predictive factors involved in SBP infections. We performed a retrospective cohort study of patients (>18 years) with SBP due to gram-positive and -negative bacteria who were enrolled from January 2006 to December 2013 at Severance Hospital in Seoul, Korea where the incidences of hepatitis B virus associated chronic liver disease, cirrhosis, and hepatocellular carcinoma are high. Only the 1st SBP episode for each patient within the study period was included in our analysis. We identified 77 patients with cirrhosis and SBP. Of these, 27 patients (35%) had gram-positive bacterial infections and 50 patients (65%) had gram-negative bacterial infections. Our univariate analysis revealed that an early stage of cirrhosis (P = 0.004), lower creatinine level (P = 0.011), lower Sequential Organ Failure Assessment (SOFA) score (P = 0.001), lower Model for End-Stage Liver Disease score (P = 0.005), and use of systemic antibiotics within 30 days before SBP diagnosis (P = 0.03) were significantly associated with gram-positive bacterial infections. Our multivariate analysis indicated that the use of systemic antibiotics within 30 days before SBP diagnosis (odds ratio, 3.94; 95% CI, 1.11–13.96; P = 0.033) and a lower SOFA score (odds ratio, 0.56; 95% CI, 0.37–0.86; P = 0.007) were independent predictive factors of SBP caused by gram-positive bacterial infections in patients with cirrhosis. However, we did not observe a statistically significant difference in the 28-day mortality between the gram-positive and -negative bacterial infection groups (40.7% vs 46.0%, respectively; P = 0.407). In this study, the incidence rate of SBP caused by gram-positive bacteria in patients with cirrhosis was similar to the

  15. Fresh layers of RNA-mediated regulation in Gram-positive bacteria.

    PubMed

    Bouloc, Philippe; Repoila, Francis

    2016-04-01

    Bacterial regulatory RNAs have been defined as diverse classes of cis and trans elements that may intervene at each step of gene expression, from RNA and protein synthesis to degradation. Here, we report on a few examples from Gram-positive bacteria that extend the definition of regulatory RNAs to include 5' and 3' UTRs that also act as cis and trans regulators. New examples unveil the existence of cis and trans acting regulatory RNAs on a single molecule. Also, we highlight data showing that a key RNA chaperone in Enterobacteriaceae, Hfq, does not fulfill the same role in Gram-positive Firmicutes. PMID:26773797

  16. Efficacy of intravenous clindamycin and methicillin in gram-positive soft tissue infections.

    PubMed Central

    Chessick, K C; Begley, L A; Curtis, L E; Hirsch, E F; Kaiser, C W; Burek, C A; Soroff, H S

    1975-01-01

    In a comparative study on a general surgical service, intravenous clindamycin phosphate or methicillin was used to treat a variety of soft tissue infections due to gram-positive organisms, chiefly staphylococci. The infections were rated according to severity, responsible organisms, and site of the infection. Excellent or good clinical and bacteriologic responses were obtained with both clindamycin and methicillin as adjuncts to basic surgical therapy in these soft tissue infections. The adverse effects of each drug were detailed, and were comparable. Clindamycin phosphate is a satisfactory substitute for methicillin in soft tissue infections secondary to gram-positive organisms. PMID:1111453

  17. Infections caused by Gram-positive bacteria: a review of the global challenge.

    PubMed

    Woodford, Neil; Livermore, David M

    2009-09-01

    Infections caused by multidrug-resistant Gram-positive bacteria represent a major public health burden, not just in terms of morbidity and mortality, but also in terms of increased expenditure on patient management and implementation of infection control measures. Staphylococcus aureus and Enterococcus spp. are established pathogens in the hospital environment, and their frequent multidrug resistance complicates therapy. The archetypal hospital "superbug", methicillin-resistant S. aureus (MRSA), regularly attracts mass-media interest and, in many countries, there is political pressure to reduce MRSA infection rates, with some progress now being made in the United Kingdom and the United States. To compound these established problems, we have witnessed the emergence and spread of virulent clones of MRSA in the community, and of Clostridium difficile in hospitals. Multidrug-resistant Streptococcus pneumoniae clones are major community pathogens in many parts of the world, but are now being challenged by new conjugate vaccines. Using combinations of molecular epidemiological tools, which characterize the resistant isolates and their resistance determinants, scientists can track highly successful bacterial strains at local, national, and international levels. These methods have provided new insights into the evolution of key pathogens, and this information may aid the design of control strategies and vaccines. In addition, the development of new antimicrobials including oxazolidinones, lipopeptides, glycylcyclines, ketolides, and new generations of fluoroquinolones, antistaphylococcal b-lactams, and glycopeptides must remain a high priority for the continued effective treatment of infections caused by resistant strains. So far, resistance to these newer agents is identified rarely in surveillance programs, but occasional reports of resistance causing therapeutic failure (e.g., with linezolid, daptomycin, telithromycin, or newer fluoroquinolones) give cause for concern

  18. Comparison of the Bruker MALDI-TOF Mass Spectrometry System and Conventional Phenotypic Methods for Identification of Gram-Positive Rods

    PubMed Central

    Barberis, Claudia; Almuzara, Marisa; Join-Lambert, Olivier; Ramírez, María Soledad; Famiglietti, Angela; Vay, Carlos

    2014-01-01

    In recent years, MALDI-TOF Mass Spectrometry (MS) method has emerged as a promising and a reliable tool for bacteria identification. In this study we compared Bruker MALDI-TOF MS and conventional phenotypic methods to identify a collection of 333 Gram-positive clinical isolates comprising 22 genera and 60 species. 16S rRNA sequencing was the reference molecular technique, and rpoB gene sequecing was used as a secondary gene target when 16Sr RNA did not allow species identification of Corynebacterium spp. We also investigate if score cut-offs values of ≥1,5 and ≥1,7 were accurate for genus and species-level identification using the Bruker system. Identification at species level was obtained for 92,49% of Gram-positive rods by MALDI-TOF MS compared to 85,89% by phenotypic method. Our data validates the score ≥1,5 for genus level and ≥1,7 for species-level identification in a large and diverse collection of Gram-positive rods. The present study has proved the accuracy of MALDI-TOF MS as an identification method in Gram-positive rods compared to currently used methods in routine laboratories. PMID:25184254

  19. Magnetosome chain arrangement and stability in magnetotactic cocci.

    PubMed

    Lins, Ulysses; Farina, Marcos

    2004-05-01

    We have studied the disposition of chains of magnetosomes inside magnetotactic cocci with light and electron microscopy. Light microscopy of isolated cocci indicated that the chains of magnetosomes are disposed on opposite sides of the cell. Electron spectroscopic imaging of whole unprocessed bacteria, showed the magnetosome chains in the cells. Freeze-etching of the cell surface allowed the observation of the close association of the chain with the cell surface. During the replication process of the freeze-etching, the magnetosome chains remained attached to the replicas, which indicates that chains were very close to the cell surface before freezing. We provide evidence that the large area of the contact faces between magnetosomes in a chain may provide an extra mechanical stability that helps keep the magnetosomes in chains even after isolation from the bacteria. Comparison with pointed magnetosomes from different cocci present in the same samples showed that the maintenance of linear chains is more difficult to be achieved because of the geometry of the crystals. PMID:15031646

  20. An extreme-halophile archaebacterium possesses the interlock type of prephenate dehydratase characteristic of the Gram-positive eubacteria

    NASA Technical Reports Server (NTRS)

    Jensen, R. A.; d'Amato, T. A.; Hochstein, L. I.

    1988-01-01

    The focal point of phenylalanine biosynthesis is a dehydratase reaction which in different organisms may be prephenate dehydratase, arogenate dehydratase, or cyclohexadienyl dehydratase. Gram-positive, Gram-negative, and cyanobacterial divisions of the eubacterial kingdom exhibit different dehydratase patterns. A new extreme-halophile isolate, which grows on defined medium and is tentatively designated as Halobacterium vallismortis CH-1, possesses the interlock type of prephenate dehydratase present in Gram-positive bacteria. In addition to the conventional sensitivity to feedback inhibition by L-phenylalanine, the phenomenon of metabolic interlock was exemplified by the sensitivity of prephenate dehydratase to allosteric effects produced by extra-pathway (remote) effectors. Thus, L-tryptophan inhibited activity while L-tyrosine, L-methionine, L-leucine and L-isoleucine activated the enzyme. L-Isoleucine and L-phenylalanine were effective at micromolar levels; other effectors operated at mM levels. A regulatory mutant selected for resistance to growth inhibition caused by beta-2-thienylalanine possessed an altered prephenate dehydratase in which a phenomenon of disproportionately low activity at low enzyme concentration was abolished. Inhibition by L-tryptophan was also lost, and activation by allosteric activators was diminished. Not only was sensitivity to feedback inhibition by L-phenylalanine lost, but the mutant enzyme was now activated by this amino acid (a mutation type previously observed in Bacillus subtilis). It remains to be seen whether this type of prephenate dehydratase will prove to be characteristic of all archaebacteria or of some archaebacterial subgroup cluster.

  1. Telavancin activity tested against a contemporary collection of Gram-positive pathogens from USA Hospitals (2007-2009).

    PubMed

    Mendes, Rodrigo E; Sader, Helio S; Farrell, David J; Jones, Ronald N

    2012-01-01

    This study updates the activity of telavancin against Gram-positive pathogens collected from USA hospitals (2007-2009). Telavancin (MIC(50/90), 0.12/0.25 μg/mL) was active against coagulase-negative staphylococci and methicillin-resistant Staphylococcus aureus (100% susceptible), for which only daptomycin (MIC(50/90), 0.25/0.5 μg/mL; 99% susceptible) and quinupristin/dalfopristin (MIC(50/90), ≤ 0.25-0.5/0.5 μg/mL; 99% susceptible) exhibited similar activity. Telavancin (MIC(50/90), 0.25/0.5 μg/mL) inhibited 96.5% of Enterococcus faecalis at the Food and Drug Administration breakpoint (MIC, ≤ 1 μg/mL), where ampicillin (99.9% susceptible), daptomycin (99.9% susceptible), and linezolid (100% susceptible) also demonstrated high-level coverage. Telavancin inhibited, respectively, 100.0% and 91.7% of VanB-phenotype E. faecalis and E. faecium at ≤ 1 μg/mL, whereas it was less active against VanA strains. Telavancin was uniformly active against Streptococcus pneumoniae and resistant subsets, and demonstrated good potency (MIC(90), 0.06-0.12 μg/mL) against other streptococci, regardless of resistance to other drugs. This assessment reveals potent activity of telavancin against Gram-positive isolates collected from USA hospitals with no evidence of emergence of resistance. PMID:22078909

  2. Caenorhabditis elegans immune conditioning with the probiotic bacterium Lactobacillus acidophilus strain NCFM enhances gram-positive immune responses.

    PubMed

    Kim, Younghoon; Mylonakis, Eleftherios

    2012-07-01

    Although the immune response of Caenorhabditis elegans to microbial infections is well established, very little is known about the effects of health-promoting probiotic bacteria on evolutionarily conserved C. elegans host responses. We found that the probiotic Gram-positive bacterium Lactobacillus acidophilus NCFM is not harmful to C. elegans and that L. acidophilus NCFM is unable to colonize the C. elegans intestine. Conditioning with L. acidophilus NCFM significantly decreased the burden of a subsequent Enterococcus faecalis infection in the nematode intestine and prolonged the survival of nematodes exposed to pathogenic strains of E. faecalis and Staphylococcus aureus, including multidrug-resistant (MDR) isolates. Preexposure of nematodes to Bacillus subtilis did not provide any beneficial effects. Importantly, L. acidophilus NCFM activates key immune signaling pathways involved in C. elegans defenses against Gram-positive bacteria, including the p38 mitogen-activated protein kinase pathway (via TIR-1 and PMK-1) and the β-catenin signaling pathway (via BAR-1). Interestingly, conditioning with L. acidophilus NCFM had a minimal effect on Gram-negative infection with Pseudomonas aeruginosa or Salmonella enterica serovar Typhimurium and had no or a negative effect on defense genes associated with Gram-negative pathogens or general stress. In conclusion, we describe a new system for the study of probiotic immune agents and our findings demonstrate that probiotic conditioning with L. acidophilus NCFM modulates specific C. elegans immunity traits. PMID:22585961

  3. Novel antibiotics targeting respiratory ATP synthesis in Gram-positive pathogenic bacteria.

    PubMed

    Balemans, Wendy; Vranckx, Luc; Lounis, Nacer; Pop, Ovidiu; Guillemont, Jérôme; Vergauwen, Karen; Mol, Selena; Gilissen, Ron; Motte, Magali; Lançois, David; De Bolle, Miguel; Bonroy, Kristien; Lill, Holger; Andries, Koen; Bald, Dirk; Koul, Anil

    2012-08-01

    Emergence of drug-resistant bacteria represents a high, unmet medical need, and discovery of new antibacterials acting on new bacterial targets is strongly needed. ATP synthase has been validated as an antibacterial target in Mycobacterium tuberculosis, where its activity can be specifically blocked by the diarylquinoline TMC207. However, potency of TMC207 is restricted to mycobacteria with little or no effect on the growth of other Gram-positive or Gram-negative bacteria. Here, we identify diarylquinolines with activity against key Gram-positive pathogens, significantly extending the antibacterial spectrum of the diarylquinoline class of drugs. These compounds inhibited growth of Staphylococcus aureus in planktonic state as well as in metabolically resting bacteria grown in a biofilm culture. Furthermore, time-kill experiments showed that the selected hits are rapidly bactericidal. Drug-resistant mutations were mapped to the ATP synthase enzyme, and biochemical analysis as well as drug-target interaction studies reveal ATP synthase as a target for these compounds. Moreover, knockdown of the ATP synthase expression strongly suppressed growth of S. aureus, revealing a crucial role of this target in bacterial growth and metabolism. Our data represent a proof of principle for using the diarylquinoline class of antibacterials in key Gram-positive pathogens. Our results suggest that broadening the antibacterial spectrum for this chemical class is possible without drifting off from the target. Development of the diarylquinolines class may represent a promising strategy for combating Gram-positive pathogens. PMID:22615276

  4. Transformations of the gram-positive honey bee pathogen, Paenibacillus larvae, by electroporation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study we developed an electrotransformation method for use with the Gram-positive bacterium Paenibacillus larvae—a deadly pathogen of honey bees. The method is substantially different from the only other electroporation method for a Paenibacillus species found in the literature. Using the ty...

  5. Oligopolyphenylenevinylene-Conjugated Oligoelectrolyte Membrane Insertion Molecules Selectively Disrupt Cell Envelopes of Gram-Positive Bacteria

    PubMed Central

    Poh, Wee Han; Chu, Justin Jang Hann; Loo, Joachim Say Chye; Bazan, Guillermo C.; Hancock, Lynn E.

    2015-01-01

    The modification of microbial membranes to achieve biotechnological strain improvement with exogenous small molecules, such as oligopolyphenylenevinylene-conjugated oligoelectrolyte (OPV-COE) membrane insertion molecules (MIMs), is an emerging biotechnological field. Little is known about the interactions of OPV-COEs with their target, the bacterial envelope. We studied the toxicity of three previously reported OPV-COEs with a selection of Gram-negative and Gram-positive organisms and demonstrated that Gram-positive bacteria are more sensitive to OPV-COEs than Gram-negative bacteria. Transmission electron microscopy demonstrated that these MIMs disrupt microbial membranes and that this occurred to a much greater degree in Gram-positive organisms. We used a number of mutants to probe the nature of MIM interactions with the microbial envelope but were unable to align the membrane perturbation effects of these compounds to previously reported membrane disruption mechanisms of, for example, cationic antimicrobial peptides. Instead, the data support the notion that OPV-COEs disrupt microbial membranes through a suspected interaction with diphosphatidylglycerol (DPG), a major component of Gram-positive membranes. The integrity of model membranes containing elevated amounts of DPG was disrupted to a greater extent by MIMs than those prepared from Escherichia coli total lipid extracts alone. PMID:25576607

  6. Antimicrobial and Efflux Pump Inhibitory Activity of Caffeoylquinic Acids from Artemisia absinthium against Gram-Positive Pathogenic Bacteria

    PubMed Central

    Fiamegos, Yiannis C.; Kastritis, Panagiotis L.; Exarchou, Vassiliki; Han, Haley; Bonvin, Alexandre M. J. J.; Vervoort, Jacques; Lewis, Kim; Hamblin, Michael R.; Tegos, George P.

    2011-01-01

    Background Traditional antibiotics are increasingly suffering from the emergence of multidrug resistance amongst pathogenic bacteria leading to a range of novel approaches to control microbial infections being investigated as potential alternative treatments. One plausible antimicrobial alternative could be the combination of conventional antimicrobial agents/antibiotics with small molecules which block multidrug efflux systems known as efflux pump inhibitors. Bioassay-driven purification and structural determination of compounds from plant sources have yielded a number of pump inhibitors which acted against gram positive bacteria. Methodology/Principal Findings In this study we report the identification and characterization of 4′,5′-O-dicaffeoylquinic acid (4′,5′-ODCQA) from Artemisia absinthium as a pump inhibitor with a potential of targeting efflux systems in a wide panel of Gram-positive human pathogenic bacteria. Separation and identification of phenolic compounds (chlorogenic acid, 3′,5′-ODCQA, 4′,5′-ODCQA) was based on hyphenated chromatographic techniques such as liquid chromatography with post column solid-phase extraction coupled with nuclear magnetic resonance spectroscopy and mass spectroscopy. Microbial susceptibility testing and potentiation of well know pump substrates revealed at least two active compounds; chlorogenic acid with weak antimicrobial activity and 4′,5′-ODCQA with pump inhibitory activity whereas 3′,5′-ODCQA was ineffective. These intitial findings were further validated with checkerboard, berberine accumulation efflux assays using efflux-related phenotypes and clinical isolates as well as molecular modeling methodology. Conclusions/Significance These techniques facilitated the direct analysis of the active components from plant extracts, as well as dramatically reduced the time needed to analyze the compounds, without the need for prior isolation. The calculated energetics of the docking poses supported the

  7. Reliability of Disk Diffusion Test Results for the Antimicrobial Susceptibility Testing of Nosocomial Gram-positive Microorganisms: Is E-test Method Better?

    PubMed Central

    Khalili, Hossein; Soltani, Rasool; Negahban, Sorrosh; Abdollahi, Alireza; Gholami, Keirollah

    2012-01-01

    Disk diffusion test is the usual applicable method for assessing the antimicrobial susceptibility pattern in most institutions and hospitals. The aim of this study was to determine the reliability of resistant-reported results of disk diffusion test for 6 routinely used antibiotics against Gram-positive microorganisms of nosocomial origin, using E-test method. Over a 1-year period, clinical specimens (e.g. blood, tracheal secretions, wound secretions, urine, etc.) were obtained from hospitalized patients with defined nosocomial infection and were cultured. Isolated Gram-positive bacteria underwent disk diffusion test for cephalothin, oxacillin, clindamycin, ciprofloxacin, vancomycin, teicoplanin (only for Enterococci), and meropenem antibiotics. E-test method was performed for all isolates resistant or intermediately sensitive to the disks of any mentioned antibiotics. Data showed compatible results of disk diffusion test with the results of E-test method for cephalothin, oxacillin, ciprofloxacin, vancomycin, and teicoplanin. None of ciprofloxacin- and vancomycin-resistant isolates in disk diffusion test showed sensitivity in E-test method. Significant differences between the results of disk diffusion and E-test methods were observed for clindamycin and meropenem against S.aureus (p = 0.01 and 0.04, respectively) and Enterococcus spp (p = 0.03 and 0.02, respectively). In order to increase the reliability of antimicrobial susceptibility results, it is recommended to perform E-test for nosocomial Gram-positive microorganisms that show antibiotic resistance by disk diffusion test and it is more important for clindamycin and meropenem. PMID:24250479

  8. Purification of equine neutrophil lysozyme and its antibacterial activity against gram-positive and gram-negative bacteria.

    PubMed

    Pellegrini, A; Waiblinger, S; Von Fellenberg, R

    1991-01-01

    Lysozyme from equine neutrophil granulocytes was isolated in a pure form by fast performance liquid chromatography, i.e. ion-exchange chromatography and reversed-phase chromatography. The lysozyme lysed Micrococcus luteus, Bacillus subtilis and Staphylococcus lentus and was also bactericidal against the Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae, Bordetella bronchiseptica, and Serratia marcescens. Staphylococcus aureus and Staphylococcus epidermidis were not lysed. The lysozyme was only very slightly bactericidal for S. epidermidis and S. aureus. Equine neutrophil lysozyme was found to be bactericidal for Gram-positive as well as for Gram-negative bacteria without further treatment. Equine and chicken egg white lysozymes were found to be immunologically related when examined using specific antisera against each of them. Both lysozymes also had very similar specific enzymatic activities against M. luteus membranes. PMID:1803722

  9. Antimicrobial susceptibilities of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents.

    PubMed

    Soriano, F; Zapardiel, J; Nieto, E

    1995-01-01

    The susceptibilities of 265 strains of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents were tested. Most strains were susceptible to vancomycin, doxycycline, and fusidic acid. Corynebacterium jeikeium and Corynebacterium urealyticum were the most resistant organisms tested. Resistance to beta-lactams, clindamycin, erythromycin, azythromycin, ciprofloxacin and gentamicin was common among strains of Corynebacterium xerosis and Corynebacterium minutissimum. Ampicillin resistance among Listeria monocytogenes was more prevalent than previously reported. Optochin, fosfomycin, and nitrofurantoin showed very little activity against most organisms tested, but the use of nitrofurantoin as a selective agent in culture medium may prevent the recovery of some isolates. Except for the unvarying activity of vancomycin against Corynebacterium species, the antimicrobial susceptibilities of the latter to other antibiotics are usually unpredictable, such that susceptibility tests are necessary for selecting the best antimicrobial treatment. PMID:7695308

  10. Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

    PubMed Central

    Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

    2000-01-01

    An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of <60 V/cm. Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

  11. Antimicrobial Growth Promoters Used in Animal Feed: Effects of Less Well Known Antibiotics on Gram-Positive Bacteria

    PubMed Central

    Butaye, Patrick; Devriese, Luc A.; Haesebrouck, Freddy

    2003-01-01

    There are not many data available on antibiotics used solely in animals and almost exclusively for growth promotion. These products include bambermycin, avilamycin, efrotomycin, and the ionophore antibiotics (monensin, salinomycin, narasin, and lasalocid). Information is also scarce for bacitracin used only marginally in human and veterinary medicine and for streptogramin antibiotics. The mechanisms of action of and resistance mechanisms against these antibiotics are described. Special emphasis is given to the prevalence of resistance among gram-positive bacteria isolated from animals and humans. Since no susceptibility breakpoints are available for most of the antibiotics discussed, an alternative approach to the interpretation of MICs is presented. Also, some pharmacokinetic data and information on the influence of these products on the intestinal flora are presented. PMID:12692092

  12. β-Lactam Resistance Mechanisms: Gram-Positive Bacteria and Mycobacterium tuberculosis.

    PubMed

    Fisher, Jed F; Mobashery, Shahriar

    2016-01-01

    The value of the β-lactam antibiotics for the control of bacterial infection has eroded with time. Three Gram-positive human pathogens that were once routinely susceptible to β-lactam chemotherapy-Streptococcus pneumoniae, Enterococcus faecium, and Staphylococcus aureus-now are not. Although a fourth bacterium, the acid-fast (but not Gram-positive-staining) Mycobacterium tuberculosis, has intrinsic resistance to earlier β-lactams, the emergence of strains of this bacterium resistant to virtually all other antibiotics has compelled the evaluation of newer β-lactam combinations as possible contributors to the multidrug chemotherapy required to control tubercular infection. The emerging molecular-level understanding of these resistance mechanisms used by these four bacteria provides the conceptual framework for bringing forward new β-lactams, and new β-lactam strategies, for the future control of their infections. PMID:27091943

  13. Blue green alga mediated synthesis of gold nanoparticles and its antibacterial efficacy against Gram positive organisms.

    PubMed

    Suganya, K S Uma; Govindaraju, K; Kumar, V Ganesh; Dhas, T Stalin; Karthick, V; Singaravelu, G; Elanchezhiyan, M

    2015-02-01

    Biofunctionalized gold nanoparticles (AuNPs) play an important role in design and development of nanomedicine. Synthesis of AuNPs from biogenic materials is environmentally benign and possesses high bacterial inhibition and bactericidal properties. In the present study, blue green alga Spirulina platensis protein mediated synthesis of AuNPs and its antibacterial activity against Gram positive bacteria is discussed. AuNPs were characterized using Ultraviolet-visible (UV-vis) spectroscopy, Fluorescence spectroscopy, Fourier Transform-Infrared (FTIR) spectroscopy, Raman spectroscopy, High Resolution-Transmission Electron Microscopy (HR-TEM) and Energy Dispersive X-ray analysis (EDAX). Stable, well defined AuNPs of smaller and uniform shape with an average size of ~ 5 nm were obtained. The antibacterial efficacy of protein functionalized AuNPs were tested against Gram positive organisms Bacillus subtilis and Staphylococcus aureus. PMID:25492207

  14. Natural transfer of conjugative transposon Tn916 between gram-positive and gram-negative bacteria.

    PubMed

    Bertram, J; Strätz, M; Dürre, P

    1991-01-01

    The conjugative streptococcal transposon Tn916 was found to transfer naturally between a variety of gram-positive and gram-negative eubacteria. Enterococcus faecalis hosting the transposon could serve as a donor for Alcaligenes eutrophus, Citrobacter freundii, and Escherichia coli at frequencies of 10(-6) to 10(-8). No transfer was observed with several phototrophic species. Mating of an E. coli strain carrying Tn916 yielded transconjugants with Bacillus subtilis, Clostridium acetobutylicum, Enterococcus faecalis, and Streptococcus lactis subsp. diacetylactis at frequencies of 10(-4) to 10(-6). Acetobacterium woodii was the only gram-positive organism tested that did not accept the transposon from a gram-negative donor. The results prove the ability of conjugative transposable elements such as Tn916 for natural cross-species gene transfer, thus potentially contributing to bacterial evolution. PMID:1846142

  15. Small regulatory RNAs from low-GC Gram-positive bacteria

    PubMed Central

    Brantl, Sabine; Brückner, Reinhold

    2014-01-01

    Small regulatory RNAs (sRNAs) that act by base-pairing were first discovered in so-called accessory DNA elements—plasmids, phages, and transposons—where they control replication, maintenance, and transposition. Since 2001, a huge body of work has been performed to predict and identify sRNAs in a multitude of bacterial genomes. The majority of chromosome-encoded sRNAs have been investigated in E. coli and other Gram-negative bacteria. However, during the past five years an increasing number of sRNAs were found in Gram-positive bacteria. Here, we outline our current knowledge on chromosome-encoded sRNAs from low-GC Gram-positive species that act by base-pairing, i.e., an antisense mechanism. We will focus on sRNAs with known targets and defined regulatory mechanisms with special emphasis on Bacillus subtilis. PMID:24576839

  16. Mid-infrared spectroscopic assessment of nanotoxicity in gram-negative vs. gram-positive bacteria.

    PubMed

    Heys, Kelly A; Riding, Matthew J; Strong, Rebecca J; Shore, Richard F; Pereira, M Glória; Jones, Kevin C; Semple, Kirk T; Martin, Francis L

    2014-03-01

    Nanoparticles appear to induce toxic effects through a variety of mechanisms including generation of reactive oxygen species (ROS), physical contact with the cell membrane and indirect catalysis due to remnants from manufacture. The development and subsequent increasing usage of nanomaterials has highlighted a growing need to characterize and assess the toxicity of nanoparticles, particularly those that may have detrimental health effects such as carbon-based nanomaterials (CBNs). Due to interactions of nanoparticles with some reagents, many traditional toxicity tests are unsuitable for use with CBNs. Infrared (IR) spectroscopy is a non-destructive, high throughput technique, which is unhindered by such problems. We explored the application of IR spectroscopy to investigate the effects of CBNs on Gram-negative (Pseudomonas fluorescens) and Gram-positive (Mycobacterium vanbaalenii PYR-1) bacteria. Two types of IR spectroscopy were compared: attenuated total reflection Fourier-transform infrared (ATR-FTIR) and synchrotron radiation-based FTIR (SR-FTIR) spectroscopy. This showed that Gram-positive and Gram-negative bacteria exhibit differing alterations when exposed to CBNs. Gram-positive bacteria appear more resistant to these agents and this may be due to the protection afforded by their more sturdy cell wall. Markers of exposure also vary according to Gram status; Amide II was consistently altered in Gram-negative bacteria and carbohydrate altered in Gram-positive bacteria. ATR-FTIR and SR-FTIR spectroscopy could both be applied to extract biochemical alterations induced by each CBN that were consistent across the two bacterial species; these may represent potential biomarkers of nanoparticle-induced alterations. Vibrational spectroscopy approaches may provide a novel means of fingerprinting the effects of CBNs in target cells. PMID:24162371

  17. Procalcitonin Levels in Gram-Positive, Gram-Negative, and Fungal Bloodstream Infections

    PubMed Central

    Ferranti, Marta; Moretti, Amedeo; Al Dhahab, Zainab Salim; Cenci, Elio; Mencacci, Antonella

    2015-01-01

    Procalcitonin (PCT) can discriminate bacterial from viral systemic infections and true bacteremia from contaminated blood cultures. The aim of this study was to evaluate PCT diagnostic accuracy in discriminating Gram-positive, Gram-negative, and fungal bloodstream infections. A total of 1,949 samples from patients with suspected bloodstream infections were included in the study. Median PCT value in Gram-negative (13.8 ng/mL, interquartile range (IQR) 3.4–44.1) bacteremias was significantly higher than in Gram-positive (2.1 ng/mL, IQR 0.6–7.6) or fungal (0.5 ng/mL, IQR 0.4–1) infections (P < 0.0001). Receiver operating characteristic analysis showed an area under the curve (AUC) for PCT of 0.765 (95% CI 0.725–0.805, P < 0.0001) in discriminating Gram-negatives from Gram-positives at the best cut-off value of 10.8 ng/mL and an AUC of 0.944 (95% CI 0.919–0.969, P < 0.0001) in discriminating Gram-negatives from fungi at the best cut-off of 1.6 ng/mL. Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative Gram-negative bacteria (17.1 ng/mL, IQR 5.9–48.5 versus 3.5 ng/mL, IQR 0.8–21.5; P < 0.0001). This study suggests that PCT may be of value to distinguish Gram-negative from Gram-positive and fungal bloodstream infections. Nevertheless, its utility to predict different microorganisms needs to be assessed in further studies. PMID:25852221

  18. Synthetic Teichoic Acid Conjugate Vaccine against Nosocomial Gram-Positive Bacteria

    PubMed Central

    Laverde, Diana; Wobser, Dominique; Romero-Saavedra, Felipe; Hogendorf, Wouter; van der Marel, Gijsbert; Berthold, Martin; Kropec, Andrea; Codee, Jeroen; Huebner, Johannes

    2014-01-01

    Lipoteichoic acids (LTA) are amphiphilic polymers that are important constituents of the cell wall of many Gram-positive bacteria. The chemical structures of LTA vary among organisms, albeit in the majority of Gram-positive bacteria the LTAs feature a common poly-1,3-(glycerolphosphate) backbone. Previously, the specificity of opsonic antibodies for this backbone present in some Gram-positive bacteria has been demonstrated, suggesting that this minimal structure may be sufficient for vaccine development. In the present work, we studied a well-defined synthetic LTA-fragment, which is able to inhibit opsonic killing of polyclonal rabbit sera raised against native LTA from Enterococcus faecalis 12030. This promising compound was conjugated with BSA and used to raise rabbit polyclonal antibodies. Subsequently, the opsonic activity of this serum was tested in an opsonophagocytic assay and specificity was confirmed by an opsonophagocytic inhibition assay. The conjugated LTA-fragment was able to induce specific opsonic antibodies that mediate killing of the clinical strains E. faecalis 12030, Enterococcus faecium E1162, and community-acquired Staphylococcus aureus strain MW2 (USA400). Prophylactic immunization with the teichoic acid conjugate and with the rabbit serum raised against this compound was evaluated in active and passive immunization studies in mice, and in an enterococcal endocarditis rat model. In all animal models, a statistically significant reduction of colony counts was observed indicating that the novel synthetic LTA-fragment conjugate is a promising vaccine candidate for active or passive immunotherapy against E. faecalis and other Gram-positive bacteria. PMID:25333799

  19. Identification of novel aminopiperidine derivatives for antibacterial activity against Gram-positive bacteria.

    PubMed

    Lee, Hee-Yeol; An, Kyung-Mi; Jung, Juyoung; Koo, Je-Min; Kim, Jeong-Geun; Yoon, Jong-Min; Lee, Myong-Jae; Jang, HyeonSoo; Lee, Hong-Sub; Park, Soobong; Kang, Jae-Hoon

    2016-07-01

    We have previously reported amidopiperidine derivatives as a novel peptide deformylase (PDF) inhibitor and evaluated its antibacterial activity against Gram-positive bacteria, but poor pharmacokinetic profiles have resulted in low efficacy in in vivo mouse models. In order to overcome these weaknesses, we newly synthesized aminopiperidine derivatives with remarkable antimicrobial properties and oral bioavailability, and also identified their in vivo efficacy against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and penicillin-resistant Streptococcus pneumoniae (PRSP). PMID:27173797

  20. Progress in the Development of Effective Vaccines to Prevent Selected Gram Positive Bacterial Infections

    PubMed Central

    Bronze, Michael S.; Dale, James B.

    2010-01-01

    Infections due to virulent gram positive bacteria, such as Staphylococcus aureus, group B streptococci and group A streptococci remain significant causes of morbidity and mortality despite progress in antimicrobial therapy. Despite significant advances in the understanding of the pathogenesis of infection due to these organisms, there are only limited strategies to prevent infection. In this paper, we review efforts to develop safe and effective vaccines that would prevent infections due to these 3 pathogens. PMID:20697258

  1. Class D β-lactamases do exist in Gram-positive bacteria

    DOE PAGESBeta

    Toth, Marta; Antunes, Nuno Tiago; Stewart, Nichole K.; Frase, Hilary; Bhattacharya, Monolekha; Smith, Clyde A.; Vakulenko, Sergei B.

    2015-11-09

    Production of β-lactamases of one of four molecular classes (A, B, C and D) is the major mechanism of bacterial resistance to β-lactams, the largest class of antibiotics, which have saved countless lives since their inception 70 years ago. Although several hundred efficient class D enzymes have been identified in Gram-negative pathogens over the last four decades, none have been reported in Gram-positive bacteria. Here we demonstrate that efficient class D β-lactamases capable of hydrolyzing a wide array of β-lactam substrates are widely disseminated in various species of environmental Gram-positive organisms. Class D enzymes of Gram-positive bacteria have a distinctmore » structural architecture and employ a unique substrate-binding mode that is quite different from that of all currently known class A, C and D β-lactamases. In conclusion, these enzymes thus constitute a previously unknown reservoir of novel antibiotic-resistance enzymes.« less

  2. Critical cell wall hole size for lysis in Gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Mitchell, Gabriel; Wiesenfeld, Kurt; Nelson, Daniel; Weitz, Joshua

    2013-03-01

    Gram-positive bacteria transport molecules necessary for their survival through holes in their cell wall. The holes in cell walls need to be large enough to let critical nutrients pass through. However, the cell wall must also function to prevent the bacteria's membrane from protruding through a large hole into the environment and lysing the cell. As such, we hypothesize that there exists a range of cell wall hole sizes that allow for molecule transport but prevent membrane protrusion. Here we develop and analyze a biophysical theory of the response of a Gram-positive cell's membrane to the formation of a hole in the cell wall. We predict a critical hole size in the range 15-24nm beyond which lysis occurs. To test our theory, we measured hole sizes in Streptococcus pyogenes cells undergoing enzymatic lysis via transmission electron microscopy. The measured hole sizes are in strong agreement with our theoretical prediction. Together, the theory and experiments provide a means to quantify the mechanisms of death of Gram-positive cells via enzymatically mediated lysis and provides insight into the range of cell wall hole sizes compatible with bacterial homeostasis.

  3. Employing carbon dots modified with vancomycin for assaying Gram-positive bacteria like Staphylococcus aureus.

    PubMed

    Zhong, Dan; Zhuo, Yan; Feng, Yuanjiao; Yang, Xiaoming

    2015-12-15

    By employing attractive performance of fluorescent carbon dots, we herein successfully established an assay for analyzing bacteria firstly. Specifically, carbon dots with blue fluorescence were initially synthesized according to a previous report, and modified with vancomycin on their surfaces. Subsequently, the prepared carbon dots were applied to detect Staphylococcus aureus accompanied with a linear range of 3.18×10(5)-1.59×10(8) cfu/mL as well as a detection limit of 9.40×10(4) cfu/mL. Compared with other regular methods, our method is more rapid and convenient in term of methodology. Meanwhile, the current strategy was applied for detection of other bacteria including Bacillus subtilis, Listeria monocytogenes, Salmonella, Pseudomonas aeruginosa and Escherichia coli, and the modified carbon dots showed obvious affinity with Gram-positive bacteria owing to the ligand-receptor interactions between vancomycin and the cell walls, suggesting its value for detecting Gram-positive bacteria. Additionally, the practicability of this sensing approach was validated by recovery experiments conducted in orange juice, confirming its potential to broaden avenues for detection of Gram-positive bacteria. PMID:26188677

  4. Mechanical Consequences of Cell-Wall Turnover in the Elongation of a Gram-Positive Bacterium

    PubMed Central

    Misra, Gaurav; Rojas, Enrique R.; Gopinathan, Ajay; Huang, Kerwyn Casey

    2013-01-01

    A common feature of walled organisms is their exposure to osmotic forces that challenge the mechanical integrity of cells while driving elongation. Most bacteria rely on their cell wall to bear osmotic stress and determine cell shape. Wall thickness can vary greatly among species, with Gram-positive bacteria having a thicker wall than Gram-negative bacteria. How wall dimensions and mechanical properties are regulated and how they affect growth have not yet been elucidated. To investigate the regulation of wall thickness in the rod-shaped Gram-positive bacterium Bacillus subtilis, we analyzed exponentially growing cells in different media. Using transmission electron and epifluorescence microscopy, we found that wall thickness and strain were maintained even between media that yielded a threefold change in growth rate. To probe mechanisms of elongation, we developed a biophysical model of the Gram-positive wall that balances the mechanical effects of synthesis of new material and removal of old material through hydrolysis. Our results suggest that cells can vary their growth rate without changing wall thickness or strain by maintaining a constant ratio of synthesis and hydrolysis rates. Our model also indicates that steady growth requires wall turnover on the same timescale as elongation, which can be driven primarily by hydrolysis rather than insertion. This perspective of turnover-driven elongation provides mechanistic insight into previous experiments involving mutants whose growth rate was accelerated by the addition of lysozyme or autolysin. Our approach provides a general framework for deconstructing shape maintenance in cells with thick walls by integrating wall mechanics with the kinetics and regulation of synthesis and turnover. PMID:23746506

  5. Fighting infections due to multidrug-resistant Gram-positive pathogens.

    PubMed

    Cornaglia, G

    2009-03-01

    Growing bacterial resistance in Gram-positive pathogens means that what were once effective and inexpensive treatments for infections caused by these bacteria are now being seriously questioned, including penicillin and macrolides for use against pneumococcal infections and-in hospitals-oxacillin for use against staphylococcal infections. As a whole, multidrug-resistant (MDR) Gram-positive pathogens are rapidly becoming an urgent and sometimes unmanageable clinical problem. Nevertheless, and despite decades of research into the effects of antibiotics, the actual risk posed to human health by antibiotic resistance has been poorly defined; the lack of reliable data concerning the outcomes resulting from antimicrobial resistance stems, in part, from problems with study designs and the methods used in resistence determination. Surprisingly little is known, too, about the actual effectiveness of the many types of intervention aimed at controlling antibiotic resistance. New antibiotics active against MDR Gram-positive pathogens have been recently introduced into clinical practice, and the antibiotic pipeline contains additional compounds at an advanced stage of development, including new glycopeptides, new anti-methicillin-resistant Staphylococcus aureus (MRSA) beta-lactams, and new diaminopyrimidines. Many novel antimicrobial agents are likely to be niche products, endowed with narrow antibacterial spectra and/or targeted at specific clinical problems. Therefore, an important educational goal will be to change the current, long-lasting attitudes of both physicians and customers towards broad-spectrum and multipurpose compounds. Scientific societies, such as the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), must play a leading role in this process. PMID:19335367

  6. Recognition of U-rich RNA by Hfq from the Gram-positive pathogen Listeria monocytogenes

    PubMed Central

    Kovach, Alexander R.; Hoff, Kirsten E.; Canty, John T.; Orans, Jillian

    2014-01-01

    Hfq is a post-transcriptional regulator that binds U- and A-rich regions of sRNAs and their target mRNAs to stimulate their annealing in order to effect translation regulation and, often, to alter their stability. The functional importance of Hfq and its RNA-binding properties are relatively well understood in Gram-negative bacteria, whereas less is known about the RNA-binding properties of this riboregulator in Gram-positive species. Here, we describe the structure of Hfq from the Gram-positive pathogen Listeria monocytogenes in its RNA-free form and in complex with a U6 oligoribonucleotide. As expected, the protein takes the canonical hexameric toroidal shape of all other known Hfq structures. The U6 RNA binds on the “proximal face” in a pocket formed by conserved residues Q9, N42, F43, and K58. Additionally residues G5 and Q6 are involved in protein-nucleic and inter-subunit contacts that promote uracil specificity. Unlike Staphylococcus aureus (Sa) Hfq, Lm Hfq requires magnesium to bind U6 with high affinity. In contrast, the longer oligo-uridine, U16, binds Lm Hfq tightly in the presence or absence of magnesium, thereby suggesting the importance of additional residues on the proximal face and possibly the lateral rim in RNA interaction. Intrinsic tryptophan fluorescence quenching (TFQ) studies reveal, surprisingly, that Lm Hfq can bind (GU)3G and U6 on its proximal and distal faces, indicating a less stringent adenine-nucleotide specificity site on the distal face as compared to the Gram-positive Hfq proteins from Sa and Bacillus subtilis and suggesting as yet uncharacterized RNA-binding modes on both faces. PMID:25150227

  7. Telavancin versus Vancomycin for Hospital-Acquired Pneumonia due to Gram-positive Pathogens

    PubMed Central

    Lalani, Tahaniyat; Corey, G. Ralph; Kanafani, Zeina A.; Nannini, Esteban C.; Rocha, Marcelo G.; Rahav, Galia; Niederman, Michael S.; Kollef, Marin H.; Shorr, Andrew F.; Lee, Patrick C.; Lentnek, Arnold L.; Luna, Carlos M.; Fagon, Jean-Yves; Torres, Antoni; Kitt, Michael M.; Genter, Fredric C.; Barriere, Steven L.; Friedland, H. David; Stryjewski, Martin E.

    2011-01-01

    Background. Telavancin is a lipoglycopeptide bactericidal against gram-positive pathogens. Methods. Two methodologically identical, double-blind studies (0015 and 0019) were conducted involving patients with hospital-acquired pneumonia (HAP) due to gram-positive pathogens, particularly methicillin-resistant Staphylococcus aureus (MRSA). Patients were randomized 1:1 to telavancin (10 mg/kg every 24 h) or vancomycin (1 g every 12 h) for 7–21 days. The primary end point was clinical response at follow-up/test-of-cure visit. Results. A total of 1503 patients were randomized and received study medication (the all-treated population). In the pooled all-treated population, cure rates with telavancin versus vancomycin were 58.9% versus 59.5% (95% confidence interval [CI] for the difference, –5.6% to 4.3%). In the pooled clinically evaluable population (n = 654), cure rates were 82.4% with telavancin and 80.7% with vancomycin (95% CI for the difference, –4.3% to 7.7%). Treatment with telavancin achieved higher cure rates in patients with monomicrobial S. aureus infection and comparable cure rates in patients with MRSA infection; in patients with mixed gram-positive/gram-negative infections, cure rates were higher in the vancomycin group. Incidence and types of adverse events were comparable between the treatment groups. Mortality rates for telavancin-treated versus vancomycin-treated patients were 21.5% versus 16.6% (95% CI for the difference, –0.7% to 10.6%) for study 0015 and 18.5% versus 20.6% (95% CI for the difference, –7.8% to 3.5%) for study 0019. Increases in serum creatinine level were more common in the telavancin group (16% vs 10%). Conclusions. The primary end point of the studies was met, indicating that telavancin is noninferior to vancomycin on the basis of clinical response in the treatment of HAP due to gram-positive pathogens. PMID:21148517

  8. Comparison of tryptophan biosynthetic operon regulation in different Gram-positive bacterial species.

    PubMed

    Gutiérrez-Preciado, Ana; Yanofsky, Charles; Merino, Enrique

    2007-09-01

    The tryptophan biosynthetic operon has been widely used as a model system for studying transcription regulation. In Bacillus subtilis, the trp operon is primarily regulated by a tryptophan-activated RNA-binding protein, TRAP. Here we show that in many other Gram-positive species the trp operon is regulated differently, by tRNA(Trp) sensing by the RNA-based T-box mechanism, with T-boxes arranged in tandem. Our analyses reveal an apparent relationship between trp operon organization and the specific regulatory mechanism(s) used. PMID:17555843

  9. Sequencing and Characterization of the xyl Operon of a Gram-Positive Bacterium, Tetragenococcus halophila

    PubMed Central

    Takeda, Yasuo; Takase, Kazuma; Yamato, Ichiro; Abe, Keietsu

    1998-01-01

    The xyl operon of a gram-positive bacterium, Tetragenococcus halophila (previously called Pediococcus halophilus), was cloned and sequenced. The DNA was about 7.7 kb long and contained genes for a ribose binding protein and part of a ribose transporter, xylR (a putative regulatory gene), and the xyl operon, along with its regulatory region and transcription termination signal, in this order. The DNA was AT rich, the GC content being 35.8%, consistent with the GC content of this gram-positive bacterium. The xyl operon consisted of three genes, xylA, encoding a xylose isomerase, xylB, encoding a xylulose kinase, and xylE, encoding a xylose transporter, with predicted molecular weights of 49,400, 56,400, and 51,600, respectively. The deduced amino acid sequences of the XylR, XylA, XylB, and XylE proteins were similar to those of the corresponding proteins in other gram-positive and -negative bacteria, the similarities being 37 to 64%. Each polypeptide of XylB and XylE was expressed functionally in Escherichia coli. XylE transported d-xylose in a sodium ion-dependent manner, suggesting that it is the first described xylose/Na+ symporter. The XylR protein contained a consensus sequence for binding catabolites of glucose, such as glucose-6-phosphate, which has been discovered in glucose and fructose kinases in bacteria. Correspondingly, the regulatory region of this operon contained a putative binding site of XylR with a palindromic structure. Furthermore, it contained a consensus sequence, CRE (catabolite-responsive element), for binding CcpA (catabolite control protein A). We speculate that the transcriptional regulation of this operon resembles the regulation of catabolite-repressible operons such as the amy, lev, xyl, and gnt operons in various gram-positive bacteria. We discuss the significance of the regulation of gene expression of this operon in T. halophila. PMID:9647823

  10. Sequencing and characterization of the xyl operon of a gram-positive bacterium, Tetragenococcus halophila.

    PubMed

    Takeda, Y; Takase, K; Yamato, I; Abe, K

    1998-07-01

    The xyl operon of a gram-positive bacterium, Tetragenococcus halophila (previously called Pediococcus halophilus), was cloned and sequenced. The DNA was about 7.7 kb long and contained genes for a ribose binding protein and part of a ribose transporter, xylR (a putative regulatory gene), and the xyl operon, along with its regulatory region and transcription termination signal, in this order. The DNA was AT rich, the GC content being 35.8%, consistent with the GC content of this gram-positive bacterium. The xyl operon consisted of three genes, xylA, encoding a xylose isomerase, xylB, encoding a xylulose kinase, and xylE, encoding a xylose transporter, with predicted molecular weights of 49,400, 56,400, and 51,600, respectively. The deduced amino acid sequences of the XylR, XylA, XylB, and XylE proteins were similar to those of the corresponding proteins in other gram-positive and -negative bacteria, the similarities being 37 to 64%. Each polypeptide of XylB and XylE was expressed functionally in Escherichia coli. XylE transported D-xylose in a sodium ion-dependent manner, suggesting that it is the first described xylose/Na+ symporter. The XylR protein contained a consensus sequence for binding catabolites of glucose, such as glucose-6-phosphate, which has been discovered in glucose and fructose kinases in bacteria. Correspondingly, the regulatory region of this operon contained a putative binding site of XylR with a palindromic structure. Furthermore, it contained a consensus sequence, CRE (catabolite-responsive element), for binding CcpA (catabolite control protein A). We speculate that the transcriptional regulation of this operon resembles the regulation of catabolite-repressible operons such as the amy, lev, xyl, and gnt operons in various gram-positive bacteria. We discuss the significance of the regulation of gene expression of this operon in T. halophila. PMID:9647823

  11. Desulfotomaculum spp. and related gram-positive sulfate-reducing bacteria in deep subsurface environments

    PubMed Central

    Aüllo, Thomas; Ranchou-Peyruse, Anthony; Ollivier, Bernard; Magot, Michel

    2013-01-01

    Gram-positive spore-forming sulfate reducers and particularly members of the genus Desulfotomaculum are commonly found in the subsurface biosphere by culture based and molecular approaches. Due to their metabolic versatility and their ability to persist as endospores. Desulfotomaculum spp. are well-adapted for colonizing environments through a slow sedimentation process. Because of their ability to grow autotrophically (H2/CO2) and produce sulfide or acetate, these microorganisms may play key roles in deep lithoautotrophic microbial communities. Available data about Desulfotomaculum spp. and related species from studies carried out from deep freshwater lakes, marine sediments, oligotrophic and organic rich deep geological settings are discussed in this review. PMID:24348471

  12. Numbers and types of anaerobic bacteria isolated from clinical specimens since 1960.

    PubMed Central

    Holland, J W; Hill, E O; Altemeier, W A

    1977-01-01

    Between 1960 and 1974, 826 specimens, excluding stool, urine, sputum, and blood, yielded 689 (83%) positive cultures, of which 403 (58.5%) contained anaerobic bacteria. This represents 48.8% of the total specimens cultured. Isolates from 153 specimens obtained and stocked from 1965 to 1974 were reidentified by current criteria. Gram-negative bacilli, primarily bacteroides, were the most frequently isolated anaerobes, being found in 70% of 153 anaerobe-positive specimens and accounting for 42% of the total anaerobes isolated. Gram-positive cocci were second in occurrence, being found in 66% of 153 specimens and accounting for 40% of the total isolates. Bacteroides fragilis was by far the most frequently isolated species. Compairson of 14 years of cumulative data with data from current studies covering 1- to 2-year periods indicated that the anaerobes isolated from clinical material have not changed significantly in type or relative numbers. PMID:833266

  13. Identification of gram-negative and gram-positive bacteria by fluorescence studies

    NASA Astrophysics Data System (ADS)

    Demchak, Jonathan; Calabrese, Joseph; Tzolov, Marian

    2011-03-01

    Several type strains of bacteria including Vibrio fischeri, Azotobacter vinelandii, Enterobacter cloacae, and Corynebacterium xerosis, were cultured in the laboratory following standard diagnostic protocol based on their individual metabolic strategies. The bacterial cultures were not further treated and they were studied in their pristine state (pure culture - axenic). The fluorescent studies were applied using a continuous wave and a pulsed excitation light sources. Emission and excitation spectra were recorded for the continuous wave excitation and they all show similar spectral features with the exception of the gram positive bacteria showing vibronic structures. The vibrational modes involved in these vibronic bands have energy typical for carbon-carbon vibrations. The fluorescence is quenched in addition of water, even a very thin layer, which confirms that the observed spectral features originate from the outer parts of the bacteria. These results allow to conclude that the fluorescence spectroscopy can be used as a method for studying the membranes of the bacteria and eventually to discriminate between gram positive and gram negative bacteria. The pulsed experiments show that the fluorescence lifetime is in the sub-microsecond range. The results indicate that the observed spectra are superposition of the emission with different lifetimes.

  14. Two Active Forms of UDP-N-Acetylglucosamine Enolpyruvyl Transferase in Gram-Positive Bacteria

    PubMed Central

    Du, Wensheng; Brown, James R.; Sylvester, Daniel R.; Huang, Jianzhong; Chalker, Alison F.; So, Chi Y.; Holmes, David J.; Payne, David J.; Wallis, Nicola G.

    2000-01-01

    Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts were made to construct a double-deletion strain, no mutants were obtained. This indicates that both genes encode active enzymes that can substitute for each other, but that the presence of a MurA function is essential to the organism. The two genes were further cloned and overexpressed, and the enzymes they encode were purified. Both enzymes catalyzed the transfer of enolpyruvate from phosphoenolpyruvate to UDP-N-acetylglucosamine, confirming they are both active UDP-N-acetylglucosamine enolpyruvyl transferases. The catalytic parameters of the two enzymes were similar, and they were both inhibited by the antibiotic fosfomycin. PMID:10894720

  15. The Mechanisms of Virulence Regulation by Small Noncoding RNAs in Low GC Gram-Positive Pathogens

    PubMed Central

    Pitman, Stephanie; Cho, Kyu Hong

    2015-01-01

    The discovery of small noncoding regulatory RNAs (sRNAs) in bacteria has grown tremendously recently, giving new insights into gene regulation. The implementation of computational analysis and RNA sequencing has provided new tools to discover and analyze potential sRNAs. Small regulatory RNAs that act by base-pairing to target mRNAs have been found to be ubiquitous and are the most abundant class of post-transcriptional regulators in bacteria. The majority of sRNA studies has been limited to E. coli and other gram-negative bacteria. However, examples of sRNAs in gram-positive bacteria are still plentiful although the detailed gene regulation mechanisms behind them are not as well understood. Strict virulence control is critical for a pathogen’s survival and many sRNAs have been found to be involved in that process. This review outlines the targets and currently known mechanisms of trans-acting sRNAs involved in virulence regulation in various gram-positive pathogens. In addition, their shared characteristics such as CU interaction motifs, the role of Hfq, and involvement in two-component regulators, riboswitches, quorum sensing, or toxin/antitoxin systems are described. PMID:26694351

  16. Cell to cell communication by autoinducing peptides in gram-positive bacteria.

    PubMed

    Sturme, Mark H J; Kleerebezem, Michiel; Nakayama, Jiro; Akkermans, Antoon D L; Vaugha, Elaine E; de Vos, Willem M

    2002-08-01

    While intercellular communication systems in Gram-negative bacteria are often based on homoserine lactones as signalling molecules, it has been shown that autoinducing peptides are involved in intercellular communication in Gram-positive bacteria. Many of these peptides are exported by dedicated systems, posttranslationally modified in various ways, and finally sensed by other cells via membrane-located receptors that are part of two-component regulatory systems. In this way the expression of a variety of functions including virulence, genetic competence and the production of antimicrobial compounds can be modulated in a co-ordinated and cell density- and growth phase-dependent manner. Occasionally the autoinducing peptide has a dual function, such as in the case of nisin that is both a signalling pheromone involved in quorum sensing and an antimicrobial peptide. Moreover, biochemical, genetic and genomic studies have shown that bacteria may contain multiple quorum sensing systems, underlining the importance of intercellular communication. Finally, in some cases different peptides may be recognised by the same receptor, while also hybrid receptors have been constructed that respond to new peptides or show novel responses. This paper provides an overview of the characteristics of autoinducing peptide-based quorum sensing systems, their application in various gram-positive bacteria, and the discovery of new systems in natural and engineered ecosystems. PMID:12448722

  17. Organic solvent adaptation of Gram positive bacteria: applications and biotechnological potentials.

    PubMed

    Torres, Sebastian; Pandey, Ashok; Castro, Guillermo R

    2011-01-01

    Organic-solvent-tolerant bacteria are considered extremophiles with different tolerance levels that change among species and strains, but also depend on the inherent toxicity of the solvent. Extensive studies to understand the mechanisms of organic solvent tolerance have been done in Gram-negative bacteria. On the contrary, the information on the solvent tolerance mechanisms in Gram-positive bacteria remains scarce. Possible shared mechanisms among Gram-(-) and Gram-(+) microorganisms include: energy-dependent active efflux pumps that export toxic organic solvents to the external medium; cis-to-trans isomerization of unsaturated membrane fatty acids and modifications in the membrane phospholipid headgroups; formation of vesicles loaded with toxic compounds; and changes in the biosynthesis rate of phospholipids to accelerate repair processes. However, additional physiological responses of Gram-(+) bacteria to organic solvents seem to be specific. The aim of the present work is to review the state of the art of responsible mechanisms for organic solvent tolerance in Gram-positive bacteria, and their industrial and environmental biotechnology potential. PMID:21504787

  18. Prognostic factors and monomicrobial necrotizing fasciitis: gram-positive versus gram-negative pathogens

    PubMed Central

    2011-01-01

    Background Monomicrobial necrotizing fasciitis is rapidly progressive and life-threatening. This study was undertaken to ascertain whether the clinical presentation and outcome for patients with this disease differ for those infected with a gram-positive as compared to gram-negative pathogen. Methods Forty-six patients with monomicrobial necrotizing fasciitis were examined retrospectively from November 2002 to January 2008. All patients received adequate broad-spectrum antibiotic therapy, aggressive resuscitation, prompt radical debridement and adjuvant hyperbaric oxygen therapy. Eleven patients were infected with a gram-positive pathogen (Group 1) and 35 patients with a gram-negative pathogen (Group 2). Results Group 2 was characterized by a higher incidence of hemorrhagic bullae and septic shock, higher APACHE II scores at 24 h post-admission, a higher rate of thrombocytopenia, and a higher prevalence of chronic liver dysfunction. Gouty arthritis was more prevalent in Group 1. For non-survivors, the incidences of chronic liver dysfunction, chronic renal failure and thrombocytopenia were higher in comparison with those for survivors. Lower level of serum albumin was also demonstrated in the non-survivors as compared to those in survivors. Conclusions Pre-existing chronic liver dysfunction, chronic renal failure, thrombocytopenia and hypoalbuminemia, and post-operative dependence on mechanical ventilation represent poor prognostic factors in monomicrobial necrotizing fasciitis. Patients with gram-negative monobacterial necrotizing fasciitis present with more fulminant sepsis. PMID:21208438

  19. Oritavancin: A New Lipoglycopeptide Antibiotic in the Treatment of Gram-Positive Infections.

    PubMed

    Brade, Karrine D; Rybak, Jeffrey M; Rybak, Michael J

    2016-03-01

    Resistance among Gram-positive organisms has been steadily increasing over the last several years; however, the development of new antibiotics to treat infections caused from these organisms has fallen short of the emergent need. Specifically, resistance among Staphylococcus aureus and Enterococcus spp. to essential antibiotics is considered a major problem. Oritavancin is a semisynthetic lipoglycopeptide antibiotic that was recently approved for the treatment of acute bacterial skin and skin structure infections (ABSSSI). While structurally related to vancomycin, oritavancin also possesses unique mechanisms of action that greatly enhance its antimicrobial potency against multi-drug resistant pathogens including both VanA- and VanB-mediated vancomycin-resistant enterococci. Owing to the addition of the highly hydrophobic tail group, oritavancin possesses a prolonged half-life ranging from 200-300 h. Although oritavancin is only currently Food and Drug Administration approved for ABSSSI, this agent may eventually play a role in additional indications where new innovative therapy is needed including bacteremia and deep-seeded, Gram-positive infections such as infective endocarditis or osteomyelitis. This review will focus on oritavancin's spectrum of activity, mechanisms of action and resistance, pharmacokinetic and pharmacodynamic properties, and the completed and ongoing clinical studies evaluating its use. PMID:26831328

  20. Synthetic Quorum Sensing and Cell-Cell Communication in Gram-Positive Bacillus megaterium.

    PubMed

    Marchand, Nicholas; Collins, Cynthia H

    2016-07-15

    The components of natural quorum-sensing (QS) systems can be used to engineer synthetic communication systems that regulate gene expression in response to chemical signals. We have used the machinery from the peptide-based agr QS system from Staphylococcus aureus to engineer a synthetic QS system in Bacillus megaterium to enable autoinduction of a target gene at high cell densities. Growth and gene expression from these synthetic QS cells were characterized in both complex and minimal media. We also split the signal production and sensing components between two strains of B. megaterium to produce sender and receiver cells and characterized the resulting communication in liquid media and on semisolid agar. The system described in this work represents the first synthetic QS and cell-cell communication system that has been engineered to function in a Gram-positive host, and it has the potential to enable the generation of dynamic gene regulatory networks in B. megaterium and other Gram-positive organisms. PMID:26203497

  1. Interfacial charge transfer between CdTe quantum dots and Gram negative vs. Gram positive bacteria.

    SciTech Connect

    Dumas, E.; Gao, C.; Suffern, D.; Bradforth, S. E.; Dimitrejevic, N. M.; Nadeau, J. L.; McGill Univ.; Univ. of Southern California

    2010-01-01

    Oxidative toxicity of semiconductor and metal nanomaterials to cells has been well established. However, it may result from many different mechanisms, some requiring direct cell contact and others resulting from the diffusion of reactive species in solution. Published results are contradictory due to differences in particle preparation, bacterial strain, and experimental conditions. It has been recently found that C{sub 60} nanoparticles can cause direct oxidative damage to bacterial proteins and membranes, including causing a loss of cell membrane potential (depolarization). However, this did not correlate with toxicity. In this study we perform a similar analysis using fluorescent CdTe quantum dots, adapting our tools to make use of the particles fluorescence. We find that two Gram positive strains show direct electron transfer to CdTe, resulting in changes in CdTe fluorescence lifetimes. These two strains also show changes in membrane potential upon nanoparticle binding. Two Gram negative strains do not show these effects - nevertheless, they are over 10-fold more sensitive to CdTe than the Gram positives. We find subtoxic levels of Cd{sup 2+} release from the particles upon irradiation of the particles, but significant production of hydroxyl radicals, suggesting that the latter is a major source of toxicity. These results help establish mechanisms of toxicity and also provide caveats for use of certain reporter dyes with fluorescent nanoparticles which will be of use to anyone performing these assays. The findings also suggest future avenues of inquiry into electron transfer processes between nanomaterials and bacteria.

  2. Sonodynamic excitation of Rose Bengal for eradication of gram-positive and gram-negative bacteria.

    PubMed

    Nakonechny, Faina; Nisnevitch, Michael; Nitzan, Yeshayahu; Nisnevitch, Marina

    2013-01-01

    Photodynamic antimicrobial chemotherapy based on photosensitizers activated by illumination is limited by poor penetration of visible light through skin and tissues. In order to overcome this problem, Rose Bengal was excited in the dark by 28 kHz ultrasound and was applied for inactivation of bacteria. It is demonstrated, for the first time, that the sonodynamic technique is effective for eradication of gram-positive Staphylococcus aureus and gram-negative Escherichia coli. The net sonodynamic effect was calculated as a 3-4 log10 reduction in bacteria concentration, depending on the cell and the Rose Bengal concentration and the treatment time. Sonodynamic treatment may become a novel and effective form of antimicrobial therapy and can be used for low-temperature sterilization of medical instruments and surgical accessories. PMID:23509759

  3. Gram-positive and gram-negative bacterial toxins in sepsis: a brief review.

    PubMed

    Ramachandran, Girish

    2014-01-01

    Bacterial sepsis is a major cause of fatality worldwide. Sepsis is a multi-step process that involves an uncontrolled inflammatory response by the host cells that may result in multi organ failure and death. Both gram-negative and gram-positive bacteria play a major role in causing sepsis. These bacteria produce a range of virulence factors that enable them to escape the immune defenses and disseminate to remote organs, and toxins that interact with host cells via specific receptors on the cell surface and trigger a dysregulated immune response. Over the past decade, our understanding of toxins has markedly improved, allowing for new therapeutic strategies to be developed. This review summarizes some of these toxins and their role in sepsis. PMID:24193365

  4. Charged Nonclassical Antifolates with Activity Against Gram-Positive and Gram-Negative Pathogens.

    PubMed

    Scocchera, Eric; Reeve, Stephanie M; Keshipeddy, Santosh; Lombardo, Michael N; Hajian, Behnoush; Sochia, Adrienne E; Alverson, Jeremy B; Priestley, Nigel D; Anderson, Amy C; Wright, Dennis L

    2016-07-14

    Although classical, negatively charged antifolates such as methotrexate possess high affinity for the dihydrofolate reductase (DHFR) enzyme, they are unable to penetrate the bacterial cell wall, rendering them poor antibacterial agents. Herein, we report a new class of charged propargyl-linked antifolates that capture some of the key contacts common to the classical antifolates while maintaining the ability to passively diffuse across the bacterial cell wall. Eight synthesized compounds exhibit extraordinary potency against Gram-positive S. aureus with limited toxicity against mammalian cells and good metabolic profile. High resolution crystal structures of two of the compounds reveal extensive interactions between the carboxylate and active site residues through a highly organized water network. PMID:27437079

  5. Surviving the Acid Test: Responses of Gram-Positive Bacteria to Low pH

    PubMed Central

    Cotter, Paul D.; Hill, Colin

    2003-01-01

    Gram-positive bacteria possess a myriad of acid resistance systems that can help them to overcome the challenge posed by different acidic environments. In this review the most common mechanisms are described: i.e., the use of proton pumps, the protection or repair of macromolecules, cell membrane changes, production of alkali, induction of pathways by transcriptional regulators, alteration of metabolism, and the role of cell density and cell signaling. We also discuss the reponses of Listeria monocytogenes, Rhodococcus, Mycobacterium, Clostridium perfringens, Staphylococcus aureus, Bacillus cereus, oral streptococci, and lactic acid bacteria to acidic environments and outline ways in which this knowledge has been or may be used to either aid or prevent bacterial survival in low-pH environments. PMID:12966143

  6. Structure of homoserine O-acetyltransferase from Staphylococcus aureus: the first Gram-positive ortholog structure

    PubMed Central

    Thangavelu, Bharani; Pavlovsky, Alexander G.; Viola, Ronald

    2014-01-01

    Homoserine O-acetyltransferase (HTA) catalyzes the formation of l-O-acetyl-homoserine from l-homoserine through the transfer of an acetyl group from acetyl-CoA. This is the first committed step required for the biosynthesis of methionine in many fungi, Gram-positive bacteria and some Gram-negative bacteria. The structure of HTA from Staphylococcus aureus (SaHTA) has been determined to a resolution of 2.45 Å. The structure belongs to the α/β-hydrolase superfamily, consisting of two distinct domains: a core α/β-domain containing the catalytic site and a lid domain assembled into a helical bundle. The active site consists of a classical catalytic triad located at the end of a deep tunnel. Structure analysis revealed some important differences for SaHTA compared with the few known structures of HTA. PMID:25286936

  7. Structure of homoserine O-acetyltransferase from Staphylococcus aureus: the first Gram-positive ortholog structure.

    PubMed

    Thangavelu, Bharani; Pavlovsky, Alexander G; Viola, Ronald

    2014-10-01

    Homoserine O-acetyltransferase (HTA) catalyzes the formation of L-O-acetyl-homoserine from L-homoserine through the transfer of an acetyl group from acetyl-CoA. This is the first committed step required for the biosynthesis of methionine in many fungi, Gram-positive bacteria and some Gram-negative bacteria. The structure of HTA from Staphylococcus aureus (SaHTA) has been determined to a resolution of 2.45 Å. The structure belongs to the α/β-hydrolase superfamily, consisting of two distinct domains: a core α/β-domain containing the catalytic site and a lid domain assembled into a helical bundle. The active site consists of a classical catalytic triad located at the end of a deep tunnel. Structure analysis revealed some important differences for SaHTA compared with the few known structures of HTA. PMID:25286936

  8. Regulating the Intersection of Metabolism and Pathogenesis in Gram-positive Bacteria

    PubMed Central

    RICHARDSON, ANTHONY R.; SOMERVILLE, GREG A.; SONENSHEIN, ABRAHAM L.

    2015-01-01

    Pathogenic bacteria must contend with immune systems that actively restrict the availability of nutrients and cofactors, and create a hostile growth environment. To deal with these hostile environments, pathogenic bacteria have evolved or acquired virulence determinants that aid in the acquisition of nutrients. This connection between pathogenesis and nutrition may explain why regulators of metabolism in nonpathogenic bacteria are used by pathogenic bacteria to regulate both metabolism and virulence. Such coordinated regulation is presumably advantageous because it conserves carbon and energy by aligning synthesis of virulence determinants with the nutritional environment. In Gram-positive bacterial pathogens, at least three metabolite-responsive global regulators, CcpA, CodY, and Rex, have been shown to coordinate the expression of metabolism and virulence genes. In this chapter, we discuss how environmental challenges alter metabolism, the regulators that respond to this altered metabolism, and how these regulators influence the host-pathogen interaction. PMID:26185086

  9. Subterfuge and sabotage: evasion of host innate defenses by invasive gram-positive bacterial pathogens.

    PubMed

    Okumura, Cheryl Y M; Nizet, Victor

    2014-01-01

    The development of a severe invasive bacterial infection in an otherwise healthy individual is one of the most striking and fascinating aspects of human medicine. A small cadre of gram-positive pathogens of the genera Streptococcus and Staphylococcus stand out for their unique invasive disease potential and sophisticated ability to counteract the multifaceted components of human innate defense. This review illustrates how these leading human disease agents evade host complement deposition and activation, impede phagocyte recruitment and activation, resist the microbicidal activities of host antimicrobial peptides and reactive oxygen species, escape neutrophil extracellular traps, and promote and accelerate phagocyte cell death through the action of pore-forming cytolysins. Understanding the molecular basis of bacterial innate immune resistance can open new avenues for therapeutic intervention geared to disabling specific virulence factors and resensitizing the pathogen to host innate immune clearance. PMID:25002085

  10. Purification Techniques of Bacteriocins from Lactic Acid Bacteria and Other Gram-Positive Bacteria

    NASA Astrophysics Data System (ADS)

    Saavedra, Lucila; Sesma, Fernando

    The search for new antimicrobial peptides produced by lactic acid ­bacteria and other Gram-positive microorganisms has become an interesting field of research in the past decades. The fact that bacteriocins are active against numerous foodborne and human pathogens, are produced by generally regarded as safe (GRAS) microorganisms, and are readily degraded by proteolytic host systems makes them attractive candidates for biotechnological applications. However, before suggesting or choosing a new bacteriocin for future technology developments, it is necessary to elucidate its biochemical structure and its mode of action, which may be carried out once the bacteriocin is purified to homogeneity. This chapter focuses on describing the main strategies used for the purification of numerous bacteriocins.

  11. Selective Inactivation of Resistant Gram-Positive Pathogens with a Light-Driven Hybrid Nanomaterial.

    PubMed

    Grüner, Malte; Tuchscherr, Lorena; Löffler, Bettina; Gonnissen, Dominik; Riehemann, Kristina; Staniford, Mark C; Kynast, Ulrich; Strassert, Cristian A

    2015-09-23

    Herein, we present a straightforward strategy to disperse highly insoluble photosensitizers in aqueous environments, without major synthetic efforts and keeping their photosensitizing abilities unaffected. A layered nanoclay was employed to adsorb and to solubilize a highly efficient yet hydrophobic Si(IV) phthalocyaninate in water. The aggregation of the photoactive dye was correlated with its photophysical properties, particularly with the ability to produce highly cytotoxic singlet oxygen. Moreover, the resulting hybrid nanomaterial is able to selectively photoinactivate Gram-positive pathogens, due to local interactions between the bacterial membranes and the negatively charged nanodiscs. Nanotoxicity assays confirmed its innocuousness toward eukaryotic cells, showing that it constitutes a new class of "phototriggered magic bullet" for the inactivation of pathogens in phototherapy, as well as in the development of coatings for self-disinfecting surfaces. PMID:26360157

  12. An Export-Specific Reporter Designed for Gram-Positive Bacteria: Application to Lactococcus lactis

    PubMed Central

    Poquet, Isabelle; Ehrlich, S. Dusko; Gruss, Alexandra

    1998-01-01

    The identification of exported proteins by fusion studies, while well developed for gram-negative bacteria, is limited for gram-positive bacteria, in part due to drawbacks of available export reporters. In this work, we demonstrate the export specificity and use of the Staphylococcus aureus secreted nuclease (Nuc) as a reporter for gram-positive bacteria. Nuc devoid of its export signal (called ΔSPNuc) was used to create two fusions whose locations could be differentiated. Nuclease activity was shown to require an extracellular location in Lactococcus lactis, thus demonstrating the suitability of ΔSPNuc to report protein export. The shuttle vector pFUN was designed to construct ΔSPNuc translational fusions whose expression signals are provided by inserted DNA. The capacity of ΔSPNuc to reveal and identify exported proteins was tested by generating an L. lactis genomic library in pFUN and by screening for Nuc activity directly in L. lactis. All ΔSPNuc fusions displaying a strong Nuc+ phenotype contained a classical or a lipoprotein-type signal peptide or single or multiple transmembrane stretches. The function of some of the predicted signals was confirmed by cell fractionation studies. The fusions analyzed included long (up to 455-amino-acid) segments of the exported proteins, all previously unknown in L. lactis. Homology searches indicate that several of them may be implicated in different cell surface functions, such as nutrient uptake, peptidoglycan assembly, environmental sensing, and protein folding. Our results with L. lactis show that ΔSPNuc is well suited to report both protein export and membrane protein topology. PMID:9537391

  13. The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium

    PubMed Central

    Santos, Joana A.; Alonso-García, Noelia; Macedo-Ribeiro, Sandra; Pereira, Pedro José Barbosa

    2014-01-01

    Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators. PMID:24847070

  14. Microcins from Enterobacteria: On the Edge Between Gram-Positive Bacteriocins and Colicins

    NASA Astrophysics Data System (ADS)

    Rebuffat, Sylvie

    Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

  15. Raman spectroscopy of xylitol uptake and metabolism in Gram-positive and Gram-negative bacteria.

    PubMed

    Palchaudhuri, Sunil; Rehse, Steven J; Hamasha, Khozima; Syed, Talha; Kurtovic, Eldar; Kurtovic, Emir; Stenger, James

    2011-01-01

    Visible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negative Escherichia coli, E. coli C and E. coli K-12. E. coli C, but not E. coli K-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in the E. coli K-12. In both viridans group streptococcus and the E. coli C derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy. PMID:21037297

  16. Raman Spectroscopy of Xylitol Uptake and Metabolism in Gram-Positive and Gram-Negative Bacteria▿

    PubMed Central

    Palchaudhuri, Sunil; Rehse, Steven J.; Hamasha, Khozima; Syed, Talha; Kurtovic, Eldar; Kurtovic, Emir; Stenger, James

    2011-01-01

    Visible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negative Escherichia coli, E. coli C and E. coli K-12. E. coli C, but not E. coli K-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in the E. coli K-12. In both viridans group streptococcus and the E. coli C derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy. PMID:21037297

  17. Ultrasound-Mediated DNA Transformation in Thermophilic Gram-Positive Anaerobes

    PubMed Central

    Ji, Yuetong; He, Zhili; Pu, Yunting; Zhou, Jizhong; Xu, Jian

    2010-01-01

    Background Thermophilic, Gram-positive, anaerobic bacteria (TGPAs) are generally recalcitrant to chemical and electrotransformation due to their special cell-wall structure and the low intrinsic permeability of plasma membranes. Methodology/Principal Findings Here we established for any Gram-positive or thermophiles an ultrasound-based sonoporation as a simple, rapid, and minimally invasive method to genetically transform TGPAs. We showed that by applying a 40 kHz ultrasound frequency over a 20-second exposure, Texas red-conjugated dextran was delivered with 27% efficiency into Thermoanaerobacter sp. X514, a TGPA that can utilize both pentose and hexose for ethanol production. Experiments that delivered plasmids showed that host-cell viability and plasmid DNA integrity were not compromised. Via sonoporation, shuttle vectors pHL015 harboring a jellyfish gfp gene and pIKM2 encoding a Clostridium thermocellum β-1,4-glucanase gene were delivered into X514 with an efficiency of 6×102 transformants/µg of methylated DNA. Delivery into X514 cells was confirmed via detecting the kanamycin-resistance gene for pIKM2, while confirmation of pHL015 was detected by visualization of fluorescence signals of secondary host-cells following a plasmid-rescue experiment. Furthermore, the foreign β-1,4-glucanase gene was functionally expressed in X514, converting the host into a prototypic thermophilic consolidated bioprocessing organism that is not only ethanologenic but cellulolytic. Conclusions/Significance In this study, we developed an ultrasound-based sonoporation method in TGPAs. This new DNA-delivery method could significantly improve the throughput in developing genetic systems for TGPAs, many of which are of industrial interest yet remain difficult to manipulate genetically. PMID:20838444

  18. Isolation and characterization of halophilic lactic acid bacteria isolated from "terasi" shrimp paste: a traditional fermented seafood product in Indonesia.

    PubMed

    Kobayashi, Takeshi; Kajiwara, Michika; Wahyuni, Mita; Kitakado, Toshihide; Hamada-Sato, Naoko; Imada, Chiaki; Watanabe, Etsuo

    2003-10-01

    Lactic acid bacteria from "terasi" shrimp paste, a highly popular fermented seafood in Indonesia were isolated and characterized. Viable cell counts were 10(4) to 10(6) cfu/g on MRS medium. All the isolates were catalase-negative, gram-positive cocci and were able to grow at 15% NaCl. Numerical phenotypic analysis showed that the isolates clustered into one group. However, they could be classified into two types: the Tetragenococcus halophilus group and the T. muriaticus group as revealed by a restriction fragment length polymorphism (RFLP) analysis and sequencing of the 16S rRNA gene. This study is the first to show that both species of Tetragenococcus are distributed in Indonesian fermented foods. PMID:14673751

  19. Sequence-Based Characterization of Tn5801-Like Genomic Islands in Tetracycline-Resistant Staphylococcus pseudintermedius and Other Gram-positive Bacteria from Humans and Animals

    PubMed Central

    de Vries, Lisbeth E.; Hasman, Henrik; Jurado Rabadán, Sonia; Agersø, Yvonne

    2016-01-01

    Antibiotic resistance in pathogens is often associated with mobile genetic elements, such as genomic islands (GI) including integrative and conjugative elements (ICEs). These can transfer resistance genes within and between bacteria from humans and/or animals. The aim of this study was to investigate whether Tn5801-like GIs carrying the tetracycline resistance gene, tet(M), are common in Staphylococcus pseudintermedius from pets, and to do an overall sequences-based characterization of Tn5801-like GIs detected in Gram-positive bacteria from humans and animals. A total of 27 tetracycline-resistant S. pseudintermedius isolates from Danish pets (1998–2005) were screened for tet(M) by PCR. Selected isolates (13) were screened for GI- or ICE-specific genes (intTn5801 or xisTn916) and their tet(M) gene was sequenced (Sanger-method). Long-range PCR mappings and whole-genome-sequencing (Illumina) were performed for selected S. pseudintermedius-isolates (seven and three isolates, respectively) as well as for human S. aureus isolates (seven and one isolates, respectively) and one porcine Enterococcus faecium isolate known to carry Tn5801-like GIs. All 27 S. pseudintermedius were positive for tet(M). Out of 13 selected isolates, seven contained Tn5801-like GIs and six contained Tn916-like ICEs. Two different Tn5801-like GI types were detected among S. pseudintermedius (Tn5801 and GI6287) - both showed high similarity compared to GenBank sequences from human pathogens. Two distinct Tn5801-like GI types were detected among the porcine E. faecium and human S. aureus isolates (Tn6014 and GI6288). Tn5801-like GIs were detected in GenBank-sequences from Gram-positive bacteria of human, animal or food origin worldwide. Known Tn5801-like GIs were divided into seven types. The results showed that Tn5801-like GIs appear to be relatively common in tetracycline-resistant S. pseudintermedius in Denmark. Almost identical Tn5801-like GIs were identified in different Gram-positive species

  20. Transport Capabilities of Eleven Gram-positive Bacteria: Comparative Genomic Analyses

    PubMed Central

    Lorca, Graciela L.; Barabote, Ravi D.; Zlotopolski, Vladimir; Tran, Can; Winnen, Brit; Hvorup, Rikki N.; Stonestrom, Aaron J.; Nguyen, Elizabeth; Huang, Li-Wen; Kim, David S.; Saier, Milton H.

    2007-01-01

    The genomes of eleven Gram-positive bacteria that are important for human health and the food industry, nine low G+C lactic acid bacteria and two high G+C Gram-positive organisms, were analyzed for their complement of genes encoding transport proteins. Thirteen to eighteen percent of their genes encode transport proteins, larger percentages than observed for most other bacteria. All of these bacteria possess channel proteins, some of which probably function to relieve osmotic stress. Amino acid uptake systems predominate over sugar and peptide cation symporters, and of the sugar uptake porters, those specific for oligosaccharides and glycosides often outnumber those for free sugars. About 10% of the total transport proteins are constituents of putative multidrug efflux pumps with Major Facilitator Superfamily (MFS)-type pumps (55%) being more prevalent than ATP-binding cassette (ABC)-type pumps (33%), which, however, usually greatly outnumber all other types. An exception to this generalization is Streptococcus thermophilus with 54% of its drug efflux pumps belonging to the ABC superfamily and 23% belonging each to the Multidrug/Oligosaccharide/Polysaccharide (MOP) superfamily and the MFS. These bacteria also display peptide efflux pumps that may function in intercellular signalling, and macromolecular efflux pumps, many of predictable specificities. Most of the bacteria analyzed have no pmf-coupled or transmembrane flow electron carriers. The one exception is Brevibacterium linens, which in addition to these carriers, also has transporters of several families not represented in the other ten bacteria examined. Comparisons with the genomes of organisms from other bacterial kingdoms revealed that lactic acid bacteria possess distinctive proportions of recognized transporter types (e.g., more porters specific for glycosides than reducing sugars). Some homologues of transporters identified had previously been identified only in Gram-negative bacteria or in eukaryotes

  1. Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria

    PubMed Central

    Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

    2013-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

  2. [Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2003 and March 2004].

    PubMed

    Shinagawa, Nagao; Taniguchi, Masaaki; Hirata, Koichi; Katsuramaki, Tadashi; Mizukuchi, Tohru; Mashita, Keiji; Ushijima, Yasuhide; Ushida, Tomohiro; Ishikawa, Syu; Aikawa, Naoki; Yo, Kikuo; Mizuno, Akira; Takayama, Tadatoshi; Sato, Takeshi; Kato, Koumei; Kubo, Shoji; Suehiro, Shigefumi; Yura, Jiro; Fujimoto, Mikio; Manabe, Tadao; Takeyama, Hiromitsu; Tanimura, Hiroshi; Taniguchi, Katsutoshi; Hasegawa, Masamitsu; Yamaue, Hiroki; Ohnishi, Hironobu; Tanaka, Noriaki; Iwagaki, Hiromi; Kimura, Hideyuki; Tsumura, Hiroaki; Fuchimoto, Sadayoshi; Yokoyama, Takashi; Sueda, Taijiro; Takesue, Yoshio; Takeuchi, Hitoshi; Yasui, Yoshimasa; Hiyama, Eizo; Ikeda, Seiyo; Yasunami, Yoichi

    2006-04-01

    Tendency of isolated bacteria from infections in general surgery during the period from April 2004 to March 2005 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 645 strains including 17 strains of Candida spp. were isolated from 226 (79.0%) of 286 patients with surgical infections. Three hundred and seventeen strains were isolated from primary infections, and 345 strains were isolated from postoperative infections. From primary infections, anaerobic Gram-positive bacteria and anaerobic Gram-negative bacteria were predominant, while aerobic Gram-positive bacteria were predominant from postoperative infections. The isolation rate of aerobic Gram-positive bacteria, such as Enterococcus spp. and Staphylococcus aureus were higher from both types of infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Pseudomonas aeruginosa, Klebsiella pneumoniae and Citrobacter freundii in this order, and from postoperative infections, P. aeruginosa was the most predominantly isolated, followed by E. coli, E. cloacae, and K. pneumoniae. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both primary infections followed by Bilophila wadsworthia. While the isolation rate of B. fragilis group was also the highest from postoperative infections, the following bacteria were Bacteroides thetaiotaomicron and B. wadsworthia in this order. In this series, we noticed no vancomycin-resistant Gram-positive cocci, but a few strains of moderately arbekacin-resistant MRSA. Carbapenem-resistant P. aeruginosa but not multidrug-resistant was seen in 13.3 per cents. Also cefazolin-resistant E. coli probably producing extended spectrum beta-lactamase was seen in 7.0 per

  3. Genetic features of circular bacteriocins produced by Gram-positive bacteria.

    PubMed

    Maqueda, Mercedes; Sánchez-Hidalgo, Marina; Fernández, Matilde; Montalbán-López, Manuel; Valdivia, Eva; Martínez-Bueno, Manuel

    2008-01-01

    This review highlights the main genetic features of circular bacteriocins, which require the co-ordinated expression of several genetic determinants. In general terms, it has been demonstrated that the expression of such structural genes must be combined with the activity of proteins involved in maturation (cleavage/circularization) and secretion outside the cell via different transporter systems, as well as multifaceted immunity mechanisms essential to ensuring the bacteria's self-protection against such strong inhibitors. Several circular antibacterial peptides produced by Gram-positive bacteria have been described to date, including enterocin AS-48, from Enterococcus faecalis S-48 (the first one characterized), gassericin A, from Lactobacillus gasseri LA39, and a similar one, reutericin 6, from Lactobacillus reuteri LA6, butyrivibriocin AR10, from the ruminal anaerobe Butyrivibrio fibrisolvens AR10, uberolysin, from Streptococcus uberis, circularin A, from Clostridium beijerinckii ATCC 25752, and subtilosin A, from Bacillus subtilis. We summarize here the progress made in the understanding of their principal genetic features over the last few years, during which the functional roles of circular proteins with wide biological activity have become clearer. PMID:18034824

  4. ε, a New Subunit of RNA Polymerase Found in Gram-Positive Bacteria

    PubMed Central

    Keller, Andrew N.; Yang, Xiao; Wiedermannová, Jana; Delumeau, Olivier; Krásný, Libor

    2014-01-01

    RNA polymerase in bacteria is a multisubunit protein complex that is essential for gene expression. We have identified a new subunit of RNA polymerase present in the high-A+T Firmicutes phylum of Gram-positive bacteria and have named it ε. Previously ε had been identified as a small protein (ω1) that copurified with RNA polymerase. We have solved the structure of ε by X-ray crystallography and show that it is not an ω subunit. Rather, ε bears remarkable similarity to the Gp2 family of phage proteins involved in the inhibition of host cell transcription following infection. Deletion of ε shows no phenotype and has no effect on the transcriptional profile of the cell. Determination of the location of ε within the assembly of RNA polymerase core by single-particle analysis suggests that it binds toward the downstream side of the DNA binding cleft. Due to the structural similarity of ε with Gp2 and the fact they bind similar regions of RNA polymerase, we hypothesize that ε may serve a role in protection from phage infection. PMID:25092033

  5. Inactivation of Gram-positive biofilms by low-temperature plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Marchal, F.; Robert, H.; Merbahi, N.; Fontagné-Faucher, C.; Yousfi, M.; Romain, C. E.; Eichwald, O.; Rondel, C.; Gabriel, B.

    2012-08-01

    This work is devoted to the evaluation of the efficiency of a new low-temperature plasma jet driven in ambient air by a dc-corona discharge to inactivate adherent cells and biofilms of Gram-positive bacteria. The selected microorganisms were lactic acid bacteria, a Weissella confusa strain which has the particularity to excrete a polysaccharide polymer (dextran) when sucrose is present. Both adherent cells and biofilms were treated with the low-temperature plasma jet for different exposure times. The antimicrobial efficiency of the plasma was tested against adherent cells and 48 h-old biofilms grown with or without sucrose. Bacterial survival was estimated using both colony-forming unit counts and fluorescence-based assays for bacterial cell viability. The experiments show the ability of the low-temperature plasma jet at atmospheric pressure to inactivate the bacteria. An increased resistance of bacteria embedded within biofilms is clearly observed. The resistance is also significantly higher with biofilm in the presence of sucrose, which indicates that dextran could play a protective role.

  6. Fate study of water-borne gram positive vegetative bacterial cells with Raman microscopy

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason; Tripathi, Ashish; Minter, Jennifer; Wilcox, Phillip; Christesen, Steven

    2010-04-01

    We present an initial bacterial fate study of Gram positive vegetative cells suspended in water and stored at ambient room temperature via Raman spectroscopy monitoring. Two types of cells were considered for this study: vegetative cells of Bacillus cereus, Bacillus thuringiensis which contain the polyhydroxybutyric acid (PHBA) as an energy storage compound and Bacillus subtlilis cells which do not. The cells were cultured specifically for this project. Immediately following the culturing phase, the bacteria were extracted, cleaned and at the onset of the study were suspended in de-ionized water and stored at room temperature. Aliquots of suspensions were deposited onto aluminum slides at different times and allowed to dry for Raman analysis. Spectra from multiple regions of each dried spot and each deposit time were acquired along with the bright-field and fluorescence images. Results were examined to investigate the effect of suspension time on the spectral signatures as well as the fate behavior of the three types of cells investigated. The cells were monitored daily for over a 14 period during which time the onset of starvation induced sporulation was observed.

  7. Organization of genes for tetrapyrrole biosynthesis in gram--positive bacteria.

    PubMed

    Johansson, P; Hederstedt, L

    1999-03-01

    Clusters of genes encoding enzymes for tetrapyrrole biosynthesis were cloned from Bacillus sphaericus, Bacillus stearothermophilus, Brevibacillus brevis and Paenibacillus macerans. The sequences of all hemX genes found, and of a 6.3 kbp hem gene cluster from P. macerans, were determined. The structure of the hem gene clusters was compared to that of other Gram-positive bacteria. The Bacillus and Brevibacillus species have a conserved organization of the genes hemAXCDBL, required for biosynthesis of uroporphyrinogen III (UroIII) from glutamyl-tRNA. In P. macerans, the hem genes for UroIII synthesis are also closely linked but their organization is different: there is no hemX gene and the gene cluster also contains genes, cysG8 and cysG(A)-hemD, encoding the enzymes required for synthesis of sirohaem from UroIII. Bacillus subtilis contains genes for three proteins, NasF, YInD and YInF, with sequence similarity to Escherichia coli CysG, which is a multi-functional protein catalysing sirohaem synthesis from UroIII. It is shown that YInF is required for sirohaem synthesis and probably catalyses the precorrin-2 to sirohaem conversion. YInD probably catalyses precorrin-2 synthesis from UroIII and NasF seems to be specific for nitrite reduction. PMID:10217486

  8. Triterpene sapogenin-polyarginine conjugates exhibit promising antibacterial activity against Gram-positive strains.

    PubMed

    Na, Heiya; Li, Xiangpeng; Zou, Cunbin; Wang, Chenhong; Wang, Chao; Liu, Keliang

    2016-07-01

    Triterpene sapogenins are a group of biologically active compounds with antibacterial activity. However, the limited solubility and poor bioavailability of triterpene sapogenins restrict their therapeutic application. Polyarginine peptides are small cationic peptides with high affinities for multiple negatively charged cell membranes and possess moderate antibacterial activities. In this study, we designed and synthesized a series of sapogenin-polyarginine conjugates in which the triterpene sapogenin moiety was covalently appended to the positively charged polyarginine via click chemistry. A clear synergistic effect was found, and the conjugates exhibited potent and selective antibacterial activity against Gram-positive strains. Among them, BAc-R3 was the most promising compound, which was also proven to be nontoxic toward mammalian cells as well as stable in plasma. The mechanism of BAc-R3 primarily involves an interaction with the bacterial membrane, similar to that of antimicrobial peptides (AMPs). This scaffold design opens an avenue for the further development of novel antibiotics comprised of the combination of a peptide and a natural product. PMID:27209170

  9. Molecular screening for alkane hydroxylase genes in Gram-negative and Gram-positive strains.

    PubMed

    Smits, T H; Röthlisberger, M; Witholt, B; van Beilen, J B

    1999-08-01

    We have developed highly degenerate oligonucleotides for polymerase chain reaction (PCR) amplification of genes related to the Pseudomonas oleovorans GPo1 and Acinetobacter sp. ADP1 alkane hydroxylases, based on a number of highly conserved sequence motifs. In all Gram-negative and in two out of three Gram-positive strains able to grow on medium- (C6-C11) or long-chain n-alkanes (C12-C16), PCR products of the expected size were obtained. The PCR fragments were cloned and sequenced and found to encode peptides with 43.2-93.8% sequence identity to the corresponding fragment of the P. oleovorans GPo1 alkane hydroxylase. Strains that were unable to grow on n-alkanes did not yield PCR products with homology to alkane hydroxylase genes. The alkane hydroxylase genes of Acinetobacter calcoaceticus EB104 and Pseudomonas putida P1 were cloned using the PCR products as probes. The two genes allow an alkane hydroxylase-negative mutant of Acinetobacter sp. ADP1 and an Escherichia coli recombinant containing all P. oleovorans alk genes except alkB, respectively, to grow on n-alkanes, showing that the cloned genes do indeed encode alkane hydroxylases. PMID:11207749

  10. Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria.

    PubMed

    Mistou, Michel-Yves; Sutcliffe, Iain C; van Sorge, Nina M

    2016-07-01

    The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. PMID:26975195

  11. Evolution of peptidoglycan biosynthesis under the selective pressure of antibiotics in Gram-positive bacteria.

    PubMed

    Mainardi, Jean-Luc; Villet, Régis; Bugg, Timothy D; Mayer, Claudine; Arthur, Michel

    2008-03-01

    Acquisition of resistance to the two classes of antibiotics therapeutically used against Gram-positive bacteria, the glycopeptides and the beta-lactams, has revealed an unexpected flexibility in the peptidoglycan assembly pathway. Glycopeptides select for diversification of the fifth position of stem pentapeptides because replacement of D-Ala by D-lactate or D-Ser at this position prevents binding of the drugs to peptidoglycan precursors. The substitution is generally well tolerated by the classical D,D-transpeptidases belonging to the penicillin-binding protein family, except by low-affinity enzymes. Total elimination of the fifth residue by a D,D-carboxypeptidase requires a novel cross-linking enzyme able to process the resulting tetrapeptide stems. This enzyme, an L,D-transpeptidase, confers cross-resistance to beta-lactams and glycopeptides. Diversification of the side chain of the precursors, presumably in response to the selective pressure of peptidoglycan endopeptidases, is controlled by aminoacyl transferases of the Fem family that redirect specific aminoacyl-tRNAs from translation to peptidoglycan synthesis. Diversification of the side chains has been accompanied by a parallel divergent evolution of the substrate specificity of the L,D-transpeptidases, in contrast to the D,D-transpeptidases, which display an unexpected broad specificity. This review focuses on the role of antibiotics in selecting or counter-selecting diversification of the structure of peptidoglycan precursors and their mode of polymerization. PMID:18266857

  12. Sortases and the Art of Anchoring Proteins to the Envelopes of Gram-Positive Bacteria

    PubMed Central

    Marraffini, Luciano A.; DeDent, Andrea C.; Schneewind, Olaf

    2006-01-01

    The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis. PMID:16524923

  13. Amplification of fluorescently labelled DNA within gram-positive and acid-fast bacteria.

    PubMed

    Vaid, A; Bishop, A H

    1999-10-01

    Representative organisms from a variety of Gram-positive genera were subjected to varying regimes in order to optimise the intracellular amplification of DNA. The bacteria were subjected to treatments with paraformaldehyde, muramidases and mild acid hydrolysis to discover which regime made each organism permeable to the amplification reagents yet allowed retention of the fluorescein-labelled amplified products within the cell. Scanning electron micrographs were used to corroborate the effectiveness of the treatments, as seen by fluorescent photomicrographs, with the damage caused to the bacterial walls. A combination of mutanolysin and lysozyme was found most effective for Bacillus cereus, whereas permeabilisation of Streptomyces coelicolor, Lactococcus lactis and Clostridium sporogenes was most effective when exposed to lysozyme only. Surprisingly, direct amplification with no pre-treatment gave the brightest fluorescence in Mycobacterium phlei. Comparing the techniques of whole cell PCR, primed in situ labelling (PRINS), and cycle PRINS showed that under the conditions used the strongest intensity of fluorescence was obtained with in situ PCR; only L. lactis and M. phlei produced signals with cycle PRINS, fluorescence was not seen for any of the organisms with PRINS. PMID:10520585

  14. Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria

    PubMed Central

    Mistou, Michel-Yves; Sutcliffe, Iain C.; van Sorge, Nina M.

    2016-01-01

    The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. PMID:26975195

  15. Biofilms affecting progression of mild steel corrosion by Gram positive Bacillus sp.

    PubMed

    Lin, Johnson; Madida, Bafana B

    2015-10-01

    The biodeterioration of metals have detrimental effects on the environment with economic implications. The deterioration of metals is of great concern to industry. In this study, mild steel coupons which were immersed in a medium containing Gram-positive Bacillus spp. and different nutrient sources were compared with the control in sterile deionized water. The weight loss of the coupons in the presence of Bacillus spp. alone was lower than the control and was further reduced when additional carbon sources, especially fructose, were added. The level of metal corrosion was significantly increased in the presence of nitrate with or without bacteria. There was a significant strong correlation between the weight loss and biofilm level (r =  0.64; p < 0.05). The addition of nitrate and Bacillus spp. produced more biofilms on the coupons and resulted in greater weight loss compared to that with Bacillus spp. only under the same conditions. However, Bacillus spp. enriched with carbon sources formed less biofilms and results in lower weight loss compared to that with Bacillus spp. only. The production of biofilm by Bacillus spp. influences the level of metal corrosion under different environmental conditions, thereby, supporting the development of a preventive strategy against corrosion. PMID:25847372

  16. Gramicidin A Mutants with Antibiotic Activity against Both Gram-Positive and Gram-Negative Bacteria.

    PubMed

    Zerfas, Breanna L; Joo, Yechaan; Gao, Jianmin

    2016-03-17

    Antimicrobial peptides (AMPs) have shown potential as alternatives to traditional antibiotics for fighting infections caused by antibiotic-resistant bacteria. One promising example of this is gramicidin A (gA). In its wild-type sequence, gA is active by permeating the plasma membrane of Gram-positive bacteria. However, gA is toxic to human red blood cells at similar concentrations to those required for it to exert its antimicrobial effects. Installing cationic side chains into gA has been shown to lower its hemolytic activity while maintaining the antimicrobial potency. In this study, we present the synthesis and the antibiotic activity of a new series of gA mutants that display cationic side chains. Specifically, by synthesizing alkylated lysine derivatives through reductive amination, we were able to create a broad selection of structures with varied activities towards Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Importantly, some of the new mutants were observed to have an unprecedented activity towards important Gram-negative pathogens, including Escherichia coli, Klebsiella pneumoniae and Psuedomonas aeruginosa. PMID:26918268

  17. Specific primers for the detection of freshwater alphaproteobacterial magnetotactic cocci.

    PubMed

    Lin, Wei; Pan, Yongxin

    2009-12-01

    Freshwater magnetotactic cocci within Alphaproteobacteria are of ecological interest due to their ubiquitous distribution in aquatic environments as well as their potential roles in iron cycling and the bulk magnetism of sediment. To effectively investigate the diversity and distribution of these cocci, specific primers (FMTCf and FMTCr) were developed. Their specificity, applicability, and effectiveness were then evaluated theoretically and empirically. PMID:20112228

  18. Microbiologic spectrum and susceptibility of isolates in delayed post-cataract surgery endophthalmitis.

    PubMed

    Jindal, Animesh; Pathengay, Avinash; Jalali, Subhadra; Mathai, Annie; Pappuru, Rajeev Reddy; Narayanan, Raja; Chhablani, Jay; Sharma, Savitri; Das, Taraprasad; Flynn, Harry W

    2015-01-01

    The objective of this study was to evaluate the microbiological spectrum and antimicrobial susceptibility of isolates in delayed post-cataract surgery endophthalmitis. A retrospective review of 33 consecutive patients with culture proven delayed post-cataract surgery endophthalmitis was done from January 2006 to March 2013. There were 22 bacterial and eleven fungal cases. Common isolates were Streptococci (seven cases), coagulase-negative staphylococci (five), Gram-negative bacilli (seven), Nocardia (two), Aspergillus (five), Candida (five). Gram-positive cocci were most susceptible to vancomycin and gatifloxacin (91.7%). Gram-negative isolates were most susceptible to ofloxacin (85.7%). Fungi being slow growing organisms are an important cause of delayed post-cataract surgery endophthalmitis. PMID:26124631

  19. Microbiologic spectrum and susceptibility of isolates in delayed post-cataract surgery endophthalmitis

    PubMed Central

    Jindal, Animesh; Pathengay, Avinash; Jalali, Subhadra; Mathai, Annie; Pappuru, Rajeev Reddy; Narayanan, Raja; Chhablani, Jay; Sharma, Savitri; Das, Taraprasad; Flynn, Harry W

    2015-01-01

    The objective of this study was to evaluate the microbiological spectrum and antimicrobial susceptibility of isolates in delayed post-cataract surgery endophthalmitis. A retrospective review of 33 consecutive patients with culture proven delayed post-cataract surgery endophthalmitis was done from January 2006 to March 2013. There were 22 bacterial and eleven fungal cases. Common isolates were Streptococci (seven cases), coagulase-negative staphylococci (five), Gram-negative bacilli (seven), Nocardia (two), Aspergillus (five), Candida (five). Gram-positive cocci were most susceptible to vancomycin and gatifloxacin (91.7%). Gram-negative isolates were most susceptible to ofloxacin (85.7%). Fungi being slow growing organisms are an important cause of delayed post-cataract surgery endophthalmitis. PMID:26124631

  20. Tedizolid: a novel oxazolidinone with potent activity against multidrug-resistant gram-positive pathogens.

    PubMed

    Zhanel, George G; Love, Riley; Adam, Heather; Golden, Alyssa; Zelenitsky, Sheryl; Schweizer, Frank; Gorityala, Bala; Lagacé-Wiens, Philippe R S; Rubinstein, Ethan; Walkty, Andrew; Gin, Alfred S; Gilmour, Matthew; Hoban, Daryl J; Lynch, Joseph P; Karlowsky, James A

    2015-02-01

    Tedizolid phosphate is a novel oxazolidinone prodrug (converted to the active form tedizolid by phosphatases in vivo) that has been developed and recently approved (June 2014) by the United States FDA for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) caused by susceptible Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Tedizolid is an oxazolidinone, but differs from other oxazolidinones by possessing a modified side chain at the C-5 position of the oxazolidinone nucleus which confers activity against certain linezolid-resistant pathogens and has an optimized C- and D-ring system that improves potency through additional binding site interactions. The mechanism of action of tedizolid is similar to other oxazolidinones and occurs through inhibition of bacterial protein synthesis by binding to 23S ribosomal RNA (rRNA) of the 50S subunit of the ribosome. As with other oxazolidinones, the spontaneous frequency of resistance development to tedizolid is low. Tedizolid is four- to eightfold more potent in vivo than linezolid against all species of staphylococci, enterococci, and streptococci, including drug-resistant phenotypes such as MRSA and vancomycin-resistant enterococci (VRE) and linezolid-resistant phenotypes. Importantly, tedizolid demonstrates activity against linezolid-resistant bacterial strains harboring the horizontally transmissible cfr gene, in the absence of certain ribosomal mutations conferring reduced oxazolidinone susceptibility. With its half-life of approximately 12 h, tedizolid is dosed once daily. It demonstrates linear pharmacokinetics, has a high oral bioavailability of approximately 90 %, and is primarily excreted by the liver as an inactive, non-circulating sulphate conjugate. Tedizolid does not require dosage adjustment in patients with any degree of renal dysfunction or hepatic dysfunction. Studies in animals have demonstrated that the pharmacodynamic parameter most closely

  1. Functional analysis of an unusual type IV pilus in the Gram-positive Streptococcus sanguinis.

    PubMed

    Gurung, Ishwori; Spielman, Ingrid; Davies, Mark R; Lala, Rajan; Gaustad, Peter; Biais, Nicolas; Pelicic, Vladimir

    2016-01-01

    Type IV pili (Tfp), which have been studied extensively in a few Gram-negative species, are the paradigm of a group of widespread and functionally versatile nano-machines. Here, we performed the most detailed molecular characterisation of Tfp in a Gram-positive bacterium. We demonstrate that the naturally competent Streptococcus sanguinis produces retractable Tfp, which like their Gram-negative counterparts can generate hundreds of piconewton of tensile force and promote intense surface-associated motility. Tfp power 'train-like' directional motion parallel to the long axis of chains of cells, leading to spreading zones around bacteria grown on plates. However, S. sanguinis Tfp are not involved in DNA uptake, which is mediated by a related but distinct nano-machine, and are unusual because they are composed of two pilins in comparable amounts, rather than one as normally seen. Whole genome sequencing identified a locus encoding all the genes involved in Tfp biology in S. sanguinis. A systematic mutational analysis revealed that Tfp biogenesis in S. sanguinis relies on a more basic machinery (only 10 components) than in Gram-negative species and that a small subset of four proteins dispensable for pilus biogenesis are essential for motility. Intriguingly, one of the piliated mutants that does not exhibit spreading retains microscopic motility but moves sideways, which suggests that the corresponding protein controls motion directionality. Besides establishing S. sanguinis as a useful new model for studying Tfp biology, these findings have important implications for our understanding of these widespread filamentous nano-machines. PMID:26435398

  2. The cholesterol-dependent cytolysin family of gram-positive bacterial toxins.

    PubMed

    Heuck, Alejandro P; Moe, Paul C; Johnson, Benjamin B

    2010-01-01

    The cholesterol-dependent cytolysins (CDCs) are a family of beta-barrel pore-forming toxins secreted by Gram-positive bacteria. These toxins are produced as water-soluble monomeric proteins that after binding to the target cell oligomerize on the membrane surface forming a ring-like pre-pore complex, and finally insert a large beta-barrel into the membrane (about 250 A in diameter). Formation of such a large transmembrane structure requires multiple and coordinated conformational changes. The presence of cholesterol in the target membrane is absolutely required for pore-formation, and therefore it was long thought that cholesterol was the cellular receptor for these toxins. However, not all the CDCs require cholesterol for binding. Intermedilysin, secreted by Streptoccocus intermedius only binds to membranes containing a protein receptor, but forms pores only if the membrane contains sufficient cholesterol. In contrast, perfringolysin O, secreted by Clostridium perfringens, only binds to membranes containing substantial amounts of cholesterol. The mechanisms by which cholesterol regulates the cytolytic activity of the CDCs are not understood at the molecular level. The C-terminus of perfringolysin O is involved in cholesterol recognition, and changes in the conformation of the loops located at the distal tip of this domain affect the toxin-membrane interactions. At the same time, the distribution of cholesterol in the membrane can modulate toxin binding. Recent studies support the concept that there is a dynamic interplay between the cholesterol-binding domain of the CDCs and the excess of cholesterol molecules in the target membrane. PMID:20213558

  3. Antibiotic utilization improvement with the Nanosphere Verigene Gram-Positive Blood Culture assay.

    PubMed

    Beal, Stacy G; Thomas, Cody; Dhiman, Neelam; Nguyen, Daniel; Qin, Huanying; Hawkins, Jennifer M; Dekmezian, Mhair; Benavides, Raul

    2015-04-01

    New technologies offer rapid identification of organisms and antimicrobial resistance markers in blood cultures several hours faster than conventional methods. We sought to determine whether implementation of the Verigene® Gram-Positive Blood Culture (BC-GP) assay paired with a well-defined results reporting algorithm would lead to earlier deescalation of empiric therapy for inpatients with methicillin-sensitive Staphylococcus aureus (MSSA) and vancomycin-resistant Enterococcus (VRE) bacteremia. The algorithm design focused on lessening the demand for pharmacist time by using electronic communications where possible. Our study compared inpatients with MSSA and VRE bacteremia from the time period before (pre-BC-GP) and after (post-BC-GP) implementation of the assay on June 25, 2013. The time from blood draw to identification and susceptibility results was decreased by 36.4 hours (P < 0.001) in the post-BC-GP group. The mean time from collection to the first dose of optimal antibiotics was reduced in the post-BC-GP group by 18.9 hours (P = 0.004) overall, with a 20.6-hour reduction (P = 0.009) for patients with MSSA and a 20.7-hour reduction (P = 0.077) for patients with VRE. Additionally, the percent of patients on empiric therapy who were placed on optimal antibiotics at any time after the Gram stain result was available increased from 64% (45/70) pre-BC-GP to 80% (43/54) post-BC-GP. The BC-GP led to an increased rate of deescalation of empiric antibiotics and a reduction in the time to optimal antibiotics for patients with MSSA and VRE bacteremia. PMID:25829639

  4. Lipoglycopeptide Antibacterial Agents in Gram-Positive Infections: A Comparative Review.

    PubMed

    Van Bambeke, Françoise

    2015-12-01

    Oritavancin, telavancin, and dalbavancin are recently marketed lipoglycopeptides that exhibit remarkable differences to conventional molecules. While dalbavancin inhibits the late stages of peptidoglycan synthesis by mainly impairing transglycosylase activity, oritavancin and telavancin anchor in the bacterial membrane by the lipophilic side chain linked to their disaccharidic moiety, disrupting membrane integrity and causing bacteriolysis. Oritavancin keeps activity against vancomycin-resistant enterocococci, being a stronger inhibitor of transpeptidase than of transglycosylase activity. These molecules have potent activity against Gram-positive organisms, most notably staphylococci (including methicillin-resistant Staphylococcus aureus and to some extent vancomycin-intermediate S. aureus), streptococci (including multidrug-resistant pneumococci), and Clostridia. All agents are indicated for the treatment of acute bacterial skin and skin structure infections, and telavancin, for hospital-acquired and ventilator-associated bacterial pneumonia. While telavancin is administered daily at 10 mg/kg, the remarkably long half-lives of oritavancin and dalbavancin allow for infrequent dosing (single dose of 1200 mg for oritavancin and 1000 mg at day 1 followed by 500 mg at day 8 for dalbavancin), which could be exploited in the future for outpatient therapy. Among possible safety issues evidenced during clinical development were an increased risk of developing osteomyelitis with oritavancin; taste disturbance, nephrotoxicity, and risk of corrected QT interval prolongation (especially in the presence of at-risk co-medications) with telavancin; and elevation of hepatic enzymes with dalbavancin. Interference with coagulation tests has been reported with oritavancin and telavancin. These drugs proved non-inferior to conventional treatments in clinical trials but their advantages may be better evidenced upon future evaluation in more severe infections. PMID:26603874

  5. Opioid Exacerbation of Gram-positive sepsis, induced by Gut Microbial Modulation, is Rescued by IL-17A Neutralization

    PubMed Central

    Meng, Jingjing; Banerjee, Santanu; Li, Dan; Sindberg, Gregory M.; Wang, Fuyuan; Ma, Jing; Roy, Sabita

    2015-01-01

    Sepsis is the predominant cause of mortality in ICUs, and opioids are the preferred analgesic in this setting. However, the role of opioids in sepsis progression has not been well characterized. The present study demonstrated that morphine alone altered the gut microbiome and selectively induced the translocation of Gram-positive gut bacteria in mice. Using a murine model of poly-microbial sepsis, we further demonstrated that morphine treatment led to predominantly Gram-positive bacterial dissemination. Activation of TLR2 by disseminated Gram-positive bacteria induced sustained up-regulation of IL-17A and IL-6. We subsequently showed that overexpression of IL-17A compromised intestinal epithelial barrier function, sustained bacterial dissemination and elevated systemic inflammation. IL-17A neutralization protected barrier integrity and improved survival in morphine-treated animals. We further demonstrated that TLR2 expressed on both dendritic cells and T cells play essential roles in IL-17A production. Additionally, intestinal sections from sepsis patients on opioids exhibit similar disruption in gut epithelial integrity, thus establishing the clinical relevance of this study. This is the first study to provide a mechanistic insight into the opioid exacerbation of sepsis and show that neutralization of IL-17A might be an effective therapeutic strategy to manage Gram-positive sepsis in patients on an opioid regimen. PMID:26039416

  6. Defining a role for Hfq in Gram-positive bacteria: evidence for Hfq-dependent antisense regulation in Listeria monocytogenes

    PubMed Central

    Nielsen, Jesper Sejrup; Lei, Lisbeth Kristensen; Ebersbach, Tine; Olsen, Anders Steno; Klitgaard, Janne Kudsk; Valentin-Hansen, Poul; Kallipolitis, Birgitte Haahr

    2010-01-01

    Small trans-encoded RNAs (sRNAs) modulate the translation and decay of mRNAs in bacteria. In Gram-negative species, antisense regulation by trans-encoded sRNAs relies on the Sm-like protein Hfq. In contrast to this, Hfq is dispensable for sRNA-mediated riboregulation in the Gram-positive species studied thus far. Here, we provide evidence for Hfq-dependent translational repression in the Gram-positive human pathogen Listeria monocytogenes, which is known to encode at least 50 sRNAs. We show that the Hfq-binding sRNA LhrA controls the translation and degradation of its target mRNA by an antisense mechanism, and that Hfq facilitates the binding of LhrA to its target. The work presented here provides the first experimental evidence for Hfq-dependent riboregulation in a Gram-positive bacterium. Our findings indicate that modulation of translation by trans-encoded sRNAs may occur by both Hfq-dependent and -independent mechanisms, thus adding another layer of complexity to sRNA-mediated riboregulation in Gram-positive species. PMID:19942685

  7. Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes

    EPA Science Inventory

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

  8. Daptomycin: an evidence-based review of its role in the treatment of Gram-positive infections

    PubMed Central

    Gonzalez-Ruiz, Armando; Seaton, R Andrew; Hamed, Kamal

    2016-01-01

    Infections caused by Gram-positive pathogens remain a major public health burden and are associated with high morbidity and mortality. Increasing rates of infection with Gram-positive bacteria and the emergence of resistance to commonly used antibiotics have led to the need for novel antibiotics. Daptomycin, a cyclic lipopeptide with rapid bactericidal activity against a wide range of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, has been shown to be effective and has a good safety profile for the approved indications of complicated skin and soft tissue infections (4 mg/kg/day), right-sided infective endocarditis caused by S. aureus, and bacteremia associated with complicated skin and soft tissue infections or right-sided infective endocarditis (6 mg/kg/day). Based on its pharmacokinetic profile and concentration-dependent bactericidal activity, high-dose (>6 mg/kg/day) daptomycin is considered an important treatment option in the management of various difficult-to-treat Gram-positive infections. Although daptomycin resistance has been documented, it remains uncommon despite the increasing use of daptomycin. To enhance activity and to minimize resistance, daptomycin in combination with other antibiotics has also been explored and found to be beneficial in certain severe infections. The availability of daptomycin via a 2-minute intravenous bolus facilitates its outpatient administration, providing an opportunity to reduce risk of health care-associated infections, improve patient satisfaction, and minimize health care costs. Daptomycin, not currently approved for use in the pediatric population, has been shown to be widely used for treating Gram-positive infections in children. PMID:27143941

  9. Daptomycin: an evidence-based review of its role in the treatment of Gram-positive infections.

    PubMed

    Gonzalez-Ruiz, Armando; Seaton, R Andrew; Hamed, Kamal

    2016-01-01

    Infections caused by Gram-positive pathogens remain a major public health burden and are associated with high morbidity and mortality. Increasing rates of infection with Gram-positive bacteria and the emergence of resistance to commonly used antibiotics have led to the need for novel antibiotics. Daptomycin, a cyclic lipopeptide with rapid bactericidal activity against a wide range of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, has been shown to be effective and has a good safety profile for the approved indications of complicated skin and soft tissue infections (4 mg/kg/day), right-sided infective endocarditis caused by S. aureus, and bacteremia associated with complicated skin and soft tissue infections or right-sided infective endocarditis (6 mg/kg/day). Based on its pharmacokinetic profile and concentration-dependent bactericidal activity, high-dose (>6 mg/kg/day) daptomycin is considered an important treatment option in the management of various difficult-to-treat Gram-positive infections. Although daptomycin resistance has been documented, it remains uncommon despite the increasing use of daptomycin. To enhance activity and to minimize resistance, daptomycin in combination with other antibiotics has also been explored and found to be beneficial in certain severe infections. The availability of daptomycin via a 2-minute intravenous bolus facilitates its outpatient administration, providing an opportunity to reduce risk of health care-associated infections, improve patient satisfaction, and minimize health care costs. Daptomycin, not currently approved for use in the pediatric population, has been shown to be widely used for treating Gram-positive infections in children. PMID:27143941

  10. Evaluation of the Andromas Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Aerobically Growing Gram-Positive Bacilli

    PubMed Central

    Farfour, E.; Leto, J.; Barritault, M.; Barberis, C.; Meyer, J.; Dauphin, B.; Le Guern, A.-S.; Leflèche, A.; Badell, E.; Guiso, N.; Leclercq, A.; Le Monnier, A.; Lecuit, M.; Rodriguez-Nava, V.; Bergeron, E.; Raymond, J.; Vimont, S.; Bille, E.; Carbonnelle, E.; Guet-Revillet, H.; Lécuyer, H.; Beretti, J.-L.; Vay, C.; Berche, P.; Ferroni, A.; Nassif, X.

    2012-01-01

    Matrix-associated laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a rapid and simple microbial identification method. Previous reports using the Biotyper system suggested that this technique requires a preliminary extraction step to identify Gram-positive rods (GPRs), a technical issue that may limit the routine use of this technique to identify pathogenic GPRs in the clinical setting. We tested the accuracy of the MALDI-TOF MS Andromas strategy to identify a set of 659 GPR isolates representing 16 bacterial genera and 72 species by the direct colony method. This bacterial collection included 40 C. diphtheriae, 13 C. pseudotuberculosis, 19 C. ulcerans, and 270 other Corynebacterium isolates, 32 L. monocytogenes and 24 other Listeria isolates, 46 Nocardia, 75 Actinomyces, 18 Actinobaculum, 11 Propionibacterium acnes, 18 Propionibacterium avidum, 30 Lactobacillus, 21 Bacillus, 2 Rhodococcus equi, 2 Erysipelothrix rhusiopathiae, and 38 other GPR isolates, all identified by reference techniques. Totals of 98.5% and 1.2% of non-Listeria GPR isolates were identified to the species or genus level, respectively. Except for L. grayi isolates that were identified to the species level, all other Listeria isolates were identified to the genus level because of highly similar spectra. These data demonstrate that rapid identification of pathogenic GPRs can be obtained without an extraction step by MALDI-TOF mass spectrometry. PMID:22692743

  11. Genome-wide gene order distances support clustering the gram-positive bacteria

    PubMed Central

    House, Christopher H.; Pellegrini, Matteo; Fitz-Gibbon, Sorel T.

    2015-01-01

    Initially using 143 genomes, we developed a method for calculating the pair-wise distance between prokaryotic genomes using a Monte Carlo method to estimate the conservation of gene order. The method was based on repeatedly selecting five or six non-adjacent random orthologs from each of two genomes and determining if the chosen orthologs were in the same order. The raw distances were then corrected for gene order convergence using an adaptation of the Jukes-Cantor model, as well as using the common distance correction D′ = −ln(1-D). First, we compared the distances found via the order of six orthologs to distances found based on ortholog gene content and small subunit rRNA sequences. The Jukes-Cantor gene order distances are reasonably well correlated with the divergence of rRNA (R2 = 0.24), especially at rRNA Jukes-Cantor distances of less than 0.2 (R2 = 0.52). Gene content is only weakly correlated with rRNA divergence (R2 = 0.04) over all distances, however, it is especially strongly correlated at rRNA Jukes-Cantor distances of less than 0.1 (R2 = 0.67). This initial work suggests that gene order may be useful in conjunction with other methods to help understand the relatedness of genomes. Using the gene order distances in 143 genomes, the relations of prokaryotes were studied using neighbor joining and agreement subtrees. We then repeated our study of the relations of prokaryotes using gene order in 172 complete genomes better representing a wider-diversity of prokaryotes. Consistently, our trees show the Actinobacteria as a sister group to the bulk of the Firmicutes. In fact, the robustness of gene order support was found to be considerably greater for uniting these two phyla than for uniting any of the proteobacterial classes together. The results are supportive of the idea that Actinobacteria and Firmicutes are closely related, which in turn implies a single origin for the gram-positive cell. PMID:25653643

  12. N-Ethylmaleimide Sensitive Factor (NSF) Inhibition Prevents Vascular Instability following Gram-Positive Pulmonary Challenge

    PubMed Central

    Lee, Ji Young; Linge, Helena M.; Ochani, Kanta; Lin, Ke; Miller, Edmund J.

    2016-01-01

    Background The Acute Respiratory Distress Syndrome (ARDS), remains a significant source of morbidity and mortality in critically ill patients. Pneumonia and sepsis are leading causes of ARDS, the pathophysiology of which includes increased pulmonary microvascular permeability and hemodynamic instability resulting in organ dysfunction. We hypothesized that N-ethylmaleimide sensitive factor (NSF) regulates exocytosis of inflammatory mediators, such as Angiopoietin-2 (Ang-2), and cytoskeletal stability by modulating myosin light chain (MLC) phosphorylation. Therefore, we challenged pulmonary cells, in vivo and in vitro, with Gram Positive bacterial cell wall components, lipoteichoic acid (LTA), and peptidoglycan (PGN) and examined the effects of NSF inhibition. Methods Mice were pre-treated with an inhibitor of NSF, TAT-NSF700 (to prevent Ang-2 release). After 30min, LTA and PGN (or saline alone) were instilled intratracheally. Pulse oximetry was assessed in awake mice prior to, and 6 hour post instillation. Post mortem, tissues were collected for studies of inflammation and Ang-2. In vitro, pulmonary endothelial cells were assessed for their responses to LTA and PGN. Results Pulmonary challenge induced signs of airspace and systemic inflammation such as changes in neutrophil counts and protein concentration in bronchoalveolar lavage fluid and tissue Ang-2 concentration, and decreased physiological parameters including oxygen saturation and pulse distention. TAT-NSF700 pre-treatment reduced LTA-PGN induced changes in lung tissue Ang-2, oxygen saturation and pulse distention. In vitro, LTA-PGN induced a rapid (<2 min) release of Ang-2, which was significantly attenuated by TAT-NSF700 or anti TLR2 antibody. Furthermore, TAT-NSF700 reduced LTA-PGN-induced MLC phosphorylation at low concentrations of 1–10 nM. Conclusions TAT-NSF700 decreased Ang-2 release, improved oxygen saturation and pulse distention following pulmonary challenge by inhibiting MLC phosphorylation, an

  13. Meso-substituted cationic porphyrins as efficient photosensitizers of gram-positive and gram-negative bacteria.

    PubMed

    Merchat, M; Bertolini, G; Giacomini, P; Villanueva, A; Jori, G

    1996-02-01

    Previous studies on the photosensitization of bacterial cells with different neutral or negatively charged porphyrins and phthalocyanines have demonstrated that, although Gram-positive bacteria are efficiently photoinactivated, Gram-negative bacteria become photosensitive only after modification of the permeability of their outer membrane. The results described in this paper show that two meso-substituted cationic porphyrins, namely tetra(4N-methyl-pyridyl)porphine tetraiodide and tetra(4N,N,N-trimethyl-anilinium)porphine, efficiently photosensitize the inactivation of Gram-negative bacteria, such as Vibrio anguillarum and Escherichia coli. A negatively charged meso-substituted porphyrin, tetra(4-sulphonatophenyl)porphine, has no appreciable photosensitizing activity towards Gram-negative bacteria, although all three porphyrins exhibit a similar subcellular distribution pattern, being mainly localized in the protoplasts or spheroplasts. Moreover, the three porphyrins show similar efficiency in the photoinactivation of the Gram-positive bacterium Entorecoccus seriolicida. PMID:8622178

  14. Dustborne and Airborne Gram-Positive and Gram-Negative Bacteria in High versus Low ERMI Homes

    PubMed Central

    Adhikari, Atin; Kettleson, Eric M.; Vesper, Stephen; Kumar, Sudhir; Popham, David L.; Schaffer, Christopher; Indugula, Reshmi; Chatterjee, Kanistha; Allam, Karteek K.; Grinshpun, Sergey A.; Reponen, Tiina

    2014-01-01

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home’s Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified into low (<5) and high (>5) ERMI groups based on the average ERMI values as well as 2011 ERMI values. Dust and air samples were collected from the homes in 2011 and all samples were analyzed for Gram-positive and Gram-negative bacteria using QPCR assays, endotoxin by the LAL assay, and N-acetyl-muramic acid using HPLC. In addition, air samples were analyzed for culturable bacteria. When average ERMI values were considered, the concentration and load of Gram-positive bacteria determined with QPCR in house dust, but not air, were significantly greater in high ERMI homes than in low ERMI homes. Furthermore, the concentration of endotoxin, but not muramic acid, in the dust was significantly greater in high ERMI than in low ERMI homes. In contrast, when ERMI values of 2011 were considered, Gram-negative bacteria determined with QPCR in air, endotoxin in air, and muramic acid in dust were significantly greater in high ERMI homes. The results suggest that both short-term and long-term mold contamination in homes could be linked with the bacterial concentrations in house dust, however, only the current mold status was associated with bacterial concentrations in air. Although correlations were found between endotoxin and Gram-negative bacteria as well as between muramic acid and Gram-positive bacteria in the entire data set, diverging associations were observed between the different measures of bacteria and the home moldiness. It is likely that concentrations of cells obtained by QPCR and concentrations of cell wall components are not equivalent and represent too broad categories to understand the bacterial composition and sources of the home microbiota. PMID:24642096

  15. In Vitro Activity of Ozenoxacin against Quinolone-Susceptible and Quinolone-Resistant Gram-Positive Bacteria

    PubMed Central

    López, Y.; Tato, M.; Espinal, P.; Garcia-Alonso, F.; Gargallo-Viola, D.; Cantón, R.

    2013-01-01

    In vitro activity of ozenoxacin, a novel nonfluorinated topical (L. D. Saravolatz and J. Leggett, Clin. Infect. Dis. 37:1210–1215, 2003) quinolone, was compared with the activities of other quinolones against well-characterized quinolone-susceptible and quinolone-resistant Gram-positive bacteria. Ozenoxacin was 3-fold to 321-fold more active than other quinolones. Ozenoxacin could represent a first-in-class nonfluorinated quinolone for the topical treatment of a broad range of dermatological infections. PMID:24080666

  16. Antibiotics for gram-positive bacterial infection: vancomycin, teicoplanin, quinupristin/dalfopristin, oxazolidinones, daptomycin, telavancin, and ceftaroline.

    PubMed

    Nailor, Michael D; Sobel, Jack D

    2011-07-01

    An overview of the mechanism of action, dosing, clinical indications, and toxicities of the glycopeptide vancomycin is provided. The emerging gram-positive bacterial resistance to antimicrobials and its mechanisms are reviewed. Strategies to control this emergence of resistance are expected to be proposed. Newer antimicrobial agents that have activity against vancomycin-resistant organisms are now available and play a critical role in the treatment of life-threatening infections. PMID:21679789

  17. Antibiotics for gram-positive bacterial infections: vancomycin, teicoplanin, quinupristin/dalfopristin, oxazolidinones, daptomycin, dalbavancin, and telavancin.

    PubMed

    Nailor, Michael D; Sobel, Jack D

    2009-12-01

    An overview of the mechanism of action, dosing, clinical indications, and toxicities of the glycopeptide vancomycin is provided. The emerging gram-positive bacterial resistance to antimicrobials and its mechanisms are reviewed. Strategies to control this emergence of resistance are expected to be proposed. Newer antimicrobial agents that have activity against vancomycin-resistant organisms are now available and play a critical role in the treatment of life-threatening infections. PMID:19909893

  18. Efficacy of linezolid on gram-positive bacterial infection in elderly patients and the risk factors associated with thrombocytopenia

    PubMed Central

    Bi, Li-qing; Zhou, Jing; Huang, Ming; Zhou, Su-ming

    2013-01-01

    Objective : Linezolid is active against drug-resistant gram-positive bacteria. However, the efficacy and safety of linezolid in the treatment of the elderly have not been well characterized. The purpose of this study was to evaluate the efficacy of linezolid in the treatment of the elderly with gram-positive bacterial infection and to investigate the risk factors associated with the development of thrombocytopenia in these patients. Methodology: This was a retrospective analysis of 50 elderly patients who were treated with intravenous linezolid for gram-positive bacterial infection. Clinical data and bacteriological responses were assessed. Risk factors associated with thrombocytopenia in elderly patients were analyzed. Results: The overall clinical cure rate of linezolid was 74%, and the bacteriological eradication rate was 69%. Thrombocytopenia occurred in 24 patients, and thrombocytopenia was associated with both the duration of treatment (P = 0.005) and the baseline platelet count (P = 0.042). Based on a logistic regression analysis, the baseline platelet count <200×109/L (OR = 0.244; 95% CI = 0.068- 0.874; P = 0.030) was identified as the only significant risk factor for linezolid-associated thrombocytopenia in elderly patients. The mean platelet count decreased significantly from the 7th day of treatment, and decreased to the lowest value 1-2 days after the end of therapy. Conclusions : Linezolid is effective and safe for the elderly with gram-positive bacterial infections. Adverse effects such as thrombocytopenia are of greater concern. Platelet counts should be monitored in patients who are treated with linezolid and that measures should be taken in advance to avoid hemorrhagic tendencies. PMID:24353639

  19. The efficacy and safety of daptomycin: first in a new class of antibiotics for Gram-positive bacteria.

    PubMed

    Rybak, M J

    2006-03-01

    In the face of increasing resistance to currently available antibiotics, there is a continued interest in the development of new drugs to treat Gram-positive infections. One such agent is the cyclic lipopeptide daptomycin-licensed in the USA for treatment of Gram-positive complicated skin and skin structure infections (cSSSIs) in 2003 and currently awaiting European approval for a similar indication (complicated skin and soft tissue infections). Daptomycin exerts its rapid bactericidal effect through insertion into and subsequent depolarisation of the bacterial cell membrane, a mode of action unlike that of any other available antibiotic. This novel mechanism of action makes the development of cross-resistance between daptomycin and other antibiotic classes unlikely. Daptomycin is highly active in vitro against a range of Gram-positive pathogens, including both susceptible and multidrug-resistant staphylococci and enterococci. Bactericidal activity has also been demonstrated against both growing and stationary-phase organisms, suggesting potential utility in the treatment of deep-seated infections. Two pivotal clinical studies comparing daptomycin 4 mg/kg per day intravenously with vancomycin or oxacillin-class antibiotics demonstrated the efficacy of daptomycin for treatment of cSSSIs. Daptomycin was well tolerated, with most adverse events considered to be unrelated to study medication, of mild-to-moderate intensity, and with a frequency and distribution similar to those associated with comparator antibiotics. The favourable clinical profile and low potential for development of resistance combine to make daptomycin a promising alternative to current agents for treatment of Gram-positive bacterial infections. PMID:16445721

  20. Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

    NASA Technical Reports Server (NTRS)

    Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

    1984-01-01

    Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

  1. RNA-mediated regulation in Gram-positive pathogens: an overview punctuated with examples from the group A Streptococcus

    PubMed Central

    Miller, Eric W.; Cao, Tram N.; Pflughoeft, Kathryn J.; Sumby, Paul

    2014-01-01

    RNA-based mechanisms of regulation represent a ubiquitous class of regulators that are associated with diverse processes including nutrient sensing, stress response, modulation of horizontal gene transfer, and virulence factor expression. While better studied in Gram-negative bacteria, the literature is replete with examples of the importance of RNA-mediated regulatory mechanisms to the virulence and fitness of Gram-positives. Regulatory RNAs are classified as cis-acting, e.g. riboswitches, which modulate the transcription, translation, or stability of co-transcribed RNA, or trans-acting, e.g. small regulatory RNAs, which target separate mRNAs or proteins. The group A Streptococcus (GAS, Streptococcus pyogenes) is a Gram-positive bacterial pathogen from which several regulatory RNA mechanisms have been characterized. The study of RNA-mediated regulation in GAS has uncovered novel concepts with respect to how small regulatory RNAs may positively regulate target mRNA stability, and to how CRISPR RNAs are processed from longer precursors. This review provides an overview of RNA-mediated regulation in Gram-positive bacteria, and is highlighted with specific examples from GAS research. The key roles that these systems play in regulating bacterial virulence are discussed and future perspectives outlined. PMID:25091277

  2. Probing interaction of gram-positive and gram-negative bacterial cells with ZnO nanorods.

    PubMed

    Jain, Aanchal; Bhargava, Richa; Poddar, Pankaj

    2013-04-01

    In the present work, the physiological effects of the ZnO nanorods on the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Aerobacter aerogenes) bacterial cells have been studied. The analysis of bacterial growth curves for various concentrations of ZnO nanorods indicates that Gram positive and Gram negative bacterial cells show inhibition at concentrations of ~64 and ~256 μg/mL respectively. The marked difference in susceptibility towards nanorods was also validated by spread plate and disk diffusion methods. In addition, the scanning electron micrographs show a clear damage to the cells via changed morphology of the cells from rod to coccoid etc. The confocal optical microscopy images of these cells also demonstrate the reduction in live cell count in the presence of ZnO nanorods. These, results clearly indicate that the antibacterial activity of ZnO nanorods is higher towards Gram positive bacterium than Gram negative bacterium which indicates that the structure of the cell wall might play a major role in the interaction with nanostructured materials and shows high sensitivity to the particle concentration. PMID:23827568

  3. ppGpp negatively impacts ribosome assembly affecting growth and antimicrobial tolerance in Gram-positive bacteria

    PubMed Central

    Corrigan, Rebecca M.; Bellows, Lauren E.; Wood, Alison

    2016-01-01

    The stringent response is a survival mechanism used by bacteria to deal with stress. It is coordinated by the nucleotides guanosine tetraphosphate and pentaphosphate [(p)ppGpp], which interact with target proteins to promote bacterial survival. Although this response has been well characterized in proteobacteria, very little is known about the effectors of this signaling system in Gram-positive species. Here, we report on the identification of seven target proteins for the stringent response nucleotides in the Gram-positive bacterium Staphylococcus aureus. We demonstrate that the GTP synthesis enzymes HprT and Gmk bind with a high affinity, leading to an inhibition of GTP production. In addition, we identified five putative GTPases—RsgA, RbgA, Era, HflX, and ObgE—as (p)ppGpp target proteins. We show that RsgA, RbgA, Era, and HflX are functional GTPases and that their activity is promoted in the presence of ribosomes but strongly inhibited by the stringent response nucleotides. By characterizing the function of RsgA in vivo, we ascertain that this protein is involved in ribosome assembly, with an rsgA deletion strain, or a strain inactivated for GTPase activity, displaying decreased growth, a decrease in the amount of mature 70S ribosomes, and an increased level of tolerance to antimicrobials. We additionally demonstrate that the interaction of ppGpp with cellular GTPases is not unique to the staphylococci, as homologs from Bacillus subtilis and Enterococcus faecalis retain this ability. Taken together, this study reveals ribosome inactivation as a previously unidentified mechanism through which the stringent response functions in Gram-positive bacteria. PMID:26951678

  4. Recognition of gram-positive intestinal bacteria by hybridoma- and colostrum-derived secretory immunoglobulin A is mediated by carbohydrates.

    PubMed

    Mathias, Amandine; Corthésy, Blaise

    2011-05-13

    Humans live in symbiosis with 10(14) commensal bacteria among which >99% resides in their gastrointestinal tract. The molecular bases pertaining to the interaction between mucosal secretory IgA (SIgA) and bacteria residing in the intestine are not known. Previous studies have demonstrated that commensals are naturally coated by SIgA in the gut lumen. Thus, understanding how natural SIgA interacts with commensal bacteria can provide new clues on its multiple functions at mucosal surfaces. Using fluorescently labeled, nonspecific SIgA or secretory component (SC), we visualized by confocal microscopy the interaction with various commensal bacteria, including Lactobacillus, Bifidobacteria, Escherichia coli, and Bacteroides strains. These experiments revealed that the interaction between SIgA and commensal bacteria involves Fab- and Fc-independent structural motifs, featuring SC as a crucial partner. Removal of glycans present on free SC or bound in SIgA resulted in a drastic drop in the interaction with gram-positive bacteria, indicating the essential role of carbohydrates in the process. In contrast, poor binding of gram-positive bacteria by control IgG was observed. The interaction with gram-negative bacteria was preserved whatever the molecular form of protein partner used, suggesting the involvement of different binding motifs. Purified SIgA and SC from either mouse hybridoma cells or human colostrum exhibited identical patterns of recognition for gram-positive bacteria, emphasizing conserved plasticity between species. Thus, sugar-mediated binding of commensals by SIgA highlights the currently underappreciated role of glycans in mediating the interaction between a highly diverse microbiota and the mucosal immune system. PMID:21454510

  5. Recognition of Gram-positive Intestinal Bacteria by Hybridoma- and Colostrum-derived Secretory Immunoglobulin A Is Mediated by Carbohydrates*

    PubMed Central

    Mathias, Amandine; Corthésy, Blaise

    2011-01-01

    Humans live in symbiosis with 1014 commensal bacteria among which >99% resides in their gastrointestinal tract. The molecular bases pertaining to the interaction between mucosal secretory IgA (SIgA) and bacteria residing in the intestine are not known. Previous studies have demonstrated that commensals are naturally coated by SIgA in the gut lumen. Thus, understanding how natural SIgA interacts with commensal bacteria can provide new clues on its multiple functions at mucosal surfaces. Using fluorescently labeled, nonspecific SIgA or secretory component (SC), we visualized by confocal microscopy the interaction with various commensal bacteria, including Lactobacillus, Bifidobacteria, Escherichia coli, and Bacteroides strains. These experiments revealed that the interaction between SIgA and commensal bacteria involves Fab- and Fc-independent structural motifs, featuring SC as a crucial partner. Removal of glycans present on free SC or bound in SIgA resulted in a drastic drop in the interaction with Gram-positive bacteria, indicating the essential role of carbohydrates in the process. In contrast, poor binding of Gram-positive bacteria by control IgG was observed. The interaction with Gram-negative bacteria was preserved whatever the molecular form of protein partner used, suggesting the involvement of different binding motifs. Purified SIgA and SC from either mouse hybridoma cells or human colostrum exhibited identical patterns of recognition for Gram-positive bacteria, emphasizing conserved plasticity between species. Thus, sugar-mediated binding of commensals by SIgA highlights the currently underappreciated role of glycans in mediating the interaction between a highly diverse microbiota and the mucosal immune system. PMID:21454510

  6. Surface Proteins of Gram-Positive Bacteria and Mechanisms of Their Targeting to the Cell Wall Envelope

    PubMed Central

    Navarre, William Wiley; Schneewind, Olaf

    1999-01-01

    The cell wall envelope of gram-positive bacteria is a macromolecular, exoskeletal organelle that is assembled and turned over at designated sites. The cell wall also functions as a surface organelle that allows gram-positive pathogens to interact with their environment, in particular the tissues of the infected host. All of these functions require that surface proteins and enzymes be properly targeted to the cell wall envelope. Two basic mechanisms, cell wall sorting and targeting, have been identified. Cell well sorting is the covalent attachment of surface proteins to the peptidoglycan via a C-terminal sorting signal that contains a consensus LPXTG sequence. More than 100 proteins that possess cell wall-sorting signals, including the M proteins of Streptococcus pyogenes, protein A of Staphylococcus aureus, and several internalins of Listeria monocytogenes, have been identified. Cell wall targeting involves the noncovalent attachment of proteins to the cell surface via specialized binding domains. Several of these wall-binding domains appear to interact with secondary wall polymers that are associated with the peptidoglycan, for example teichoic acids and polysaccharides. Proteins that are targeted to the cell surface include muralytic enzymes such as autolysins, lysostaphin, and phage lytic enzymes. Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections. In this review we describe the mechanisms for both sorting and targeting of proteins to the envelope of gram-positive bacteria and review the functions of known surface proteins. PMID:10066836

  7. Bacteriophages and bacteriophage-derived endolysins as potential therapeutics to combat Gram-positive spore forming bacteria.

    PubMed

    Nakonieczna, A; Cooper, C J; Gryko, R

    2015-09-01

    Since their discovery in 1915, bacteriophages have been routinely used within Eastern Europe to treat a variety of bacterial infections. Although initially ignored by the West due to the success of antibiotics, increasing levels and diversity of antibiotic resistance is driving a renaissance for bacteriophage-derived therapy, which is in part due to the highly specific nature of bacteriophages as well as their relative abundance. This review focuses on the bacteriophages and derived lysins of relevant Gram-positive spore formers within the Bacillus cereus group and Clostridium genus that could have applications within the medical, food and environmental sectors. PMID:26109320

  8. Antimicrobial activity of daptomycin tested against Gram-positive pathogens collected in Europe, Latin America, and selected countries in the Asia-Pacific Region (2011).

    PubMed

    Sader, Helio S; Flamm, Robert K; Jones, Ronald N

    2013-04-01

    We report the results of the international daptomycin surveillance programs for Europe, Latin America, and selected Asia-Pacific nations. A total of 7948 consecutive Gram-positive organisms of clinical significance were collected in 2011 and susceptibility tested against daptomycin and various comparator agents by Clinical and Laboratory Standards Institute (Clinical and Laboratory Standards Institute. M07-A9. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard: ninth edition Wayne, PA: CLSI. 2012.; Cubicin Package Insert 2012. Cubist Pharmaceuticals, Inc, Lexington, MA. Available at http://www.cubicin.com/pdf/PrescribingInformation.pdf. Accessed January 1, 2012.) broth microdilution methods. The test medium was adjusted to contain physiological levels of calcium (50 mg/L) when testing daptomycin. Daptomycin exhibited potent activity against methicillin-susceptible and -resistant Staphylococcus aureus overall and for each region (MIC(50/90), 0.25-0.5/0.5 μg/mL), with susceptibility rates at 100.0% in Latin America, Australia/New Zealand, and India, and at 99.9% in Europe. The daptomycin MIC(50/90) for coagulase-negative staphylococci was also at 0.25-0.5/0.5 μg/mL, and only 1 isolate was considered nonsusceptible with a MIC value at 2 μg/mL. Daptomycin was also highly active against Enterococcus faecalis (MIC(50/90), 1/1-2 μg/mL) and E. faecium (MIC(50/90), 2/2 μg/mL for both vancomycin-susceptible and -resistant isolates). All enterococcal isolates were susceptible to daptomycin (MIC, ≤4 μg/mL) and tigecycline. Susceptibility to linezolid for E. faecalis was at 100.0%, while for E. faecium regional susceptibility rates were at 100.0% except in Europe (99.0%). Viridans group streptococci (MIC(50/90), 0.25/1 μg/mL) and β-haemolytic streptococci (MIC(50/90), ≤0.06/0.25 μg/mL) continue to be very susceptible to daptomycin. In summary, the results of this investigation document the high potency and

  9. Influenza-induced type I interferon enhances susceptibility to gram-negative and gram-positive bacterial pneumonia in mice

    PubMed Central

    Lee, Benjamin; Robinson, Keven M.; McHugh, Kevin J.; Scheller, Erich V.; Mandalapu, Sivanarayana; Chen, Chen; Di, Y. Peter; Clay, Michelle E.; Enelow, Richard I.; Dubin, Patricia J.

    2015-01-01

    Suppression of type 17 immunity by type I interferon (IFN) during influenza A infection has been shown to enhance susceptibility to secondary bacterial pneumonia. Although this mechanism has been described in coinfection with gram-positive bacteria, it is unclear whether similar mechanisms may impair lung defense against gram-negative infections. Furthermore, precise delineation of the duration of type I IFN-associated susceptibility to bacterial infection remains underexplored. Therefore, we investigated the effects of preceding influenza A virus infection on subsequent challenge with the gram-negative bacteria Escherichia coli or Pseudomonas aeruginosa and the temporal association between IFN expression with susceptibility to Staphylococcus aureus challenge in a mouse model of influenza and bacterial coinfection. Here we demonstrate that preceding influenza A virus led to increased lung E. coli and P. aeruginosa bacterial burden, which was associated with suppression of type 17 immunity and attenuation of antimicrobial peptide expression. Enhanced susceptibility to S. aureus coinfection ceased at day 14 of influenza infection, when influenza-associated type I IFN levels had returned to baseline levels, further suggesting a key role for type I IFN in coinfection pathogenesis. These findings further implicate type I IFN-associated suppression of type 17 immunity and antimicrobial peptide production as a conserved mechanism for enhanced susceptibility to both gram-positive and gram-negative bacterial coinfection during influenza infection. PMID:26001778

  10. Quantitative proteomic view associated with resistance to clinically important antibiotics in Gram-positive bacteria: a systematic review

    PubMed Central

    Lee, Chang-Ro; Lee, Jung Hun; Park, Kwang Seung; Jeong, Byeong Chul; Lee, Sang Hee

    2015-01-01

    The increase of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) poses a worldwide and serious health threat. Although new antibiotics, such as daptomycin and linezolid, have been developed for the treatment of infections of Gram-positive pathogens, the emergence of daptomycin-resistant and linezolid-resistant strains during therapy has now increased clinical treatment failures. In the past few years, studies using quantitative proteomic methods have provided a considerable progress in understanding antibiotic resistance mechanisms. In this review, to understand the resistance mechanisms to four clinically important antibiotics (methicillin, vancomycin, linezolid, and daptomycin) used in the treatment of Gram-positive pathogens, we summarize recent advances in studies on resistance mechanisms using quantitative proteomic methods, and also examine proteins playing an important role in the bacterial mechanisms of resistance to the four antibiotics. Proteomic researches can identify proteins whose expression levels are changed in the resistance mechanism to only one antibiotic, such as LiaH in daptomycin resistance and PrsA in vancomycin resistance, and many proteins simultaneously involved in resistance mechanisms to various antibiotics. Most of resistance-related proteins, which are simultaneously associated with resistance mechanisms to several antibiotics, play important roles in regulating bacterial envelope biogenesis, or compensating for the fitness cost of antibiotic resistance. Therefore, proteomic data confirm that antibiotic resistance requires the fitness cost and the bacterial envelope is an important factor in antibiotic resistance. PMID:26322035

  11. A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria.

    PubMed

    Quiles-Puchalt, Nuria; Tormo-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Iñigo; Novick, Richard P; Christie, Gail E; Penadés, José R

    2013-08-01

    The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria. PMID:23771138

  12. CRIg Functions as a Macrophage Pattern Recognition Receptor to Directly Bind and Capture Blood-Borne Gram-Positive Bacteria.

    PubMed

    Zeng, Zhutian; Surewaard, Bas G J; Wong, Connie H Y; Geoghegan, Joan A; Jenne, Craig N; Kubes, Paul

    2016-07-13

    Kupffer cells (KCs), the vast pool of intravascular macrophages in the liver, help to clear blood-borne pathogens. The mechanisms by which KCs capture circulating pathogens remain unknown. Here we use intra-vital imaging of mice infected with Staphylococcus aureus to directly visualize the dynamic process of bacterial capture in the liver. Circulating S. aureus were captured by KCs in a manner dependent on the macrophage complement receptor CRIg, but the process was independent of complement. CRIg bound Staphylococcus aureus specifically through recognition of lipoteichoic acid (LTA), but not cell-wall-anchored surface proteins or peptidoglycan. Blocking the recognition between CRIg and LTA in vivo diminished the bacterial capture in liver and led to systemic bacterial dissemination. All tested Gram-positive, but not Gram-negative, bacteria bound CRIg in a complement-independent manner. These findings reveal a pattern recognition role for CRIg in the direct capture of circulating Gram-positive bacteria from the bloodstream. PMID:27345697

  13. A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria

    PubMed Central

    Quiles-Puchalt, Nuria; Tormo-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Íñigo; Novick, Richard P.; Christie, Gail E.; Penadés, José R.

    2013-01-01

    The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria. PMID:23771138

  14. Ultrasound-induced inactivation of gram-negative and gram-positive bacteria in secondary treated municipal wastewater.

    PubMed

    Drakopoulou, S; Terzakis, S; Fountoulakis, M S; Mantzavinos, D; Manios, T

    2009-06-01

    The effect of 24kHz, high energy ultrasound in the presence and absence of titanium dioxide particles on the destruction of different bacteria groups was studied. Applying a total of 1500W/L for 60min (this corresponds to 5400kJ/L specific nominal energy), the mean destruction of gram-negative bacteria such as total coliforms, faecal coliforms and Pseudomonas spp. was 99.5%, 99.2% and 99.7%, respectively. More recalcitrant to sonolytic inactivation were the gram-positive bacteria Clostridium perfringens and faecal streptococci with a mean removal of 66% and 84%, respectively. The presence of 5g/L TiO(2) generally enhanced the destruction of gram-negative bacteria, yielding three to five logs reduction. On the other hand, the relatively weak sonochemical inactivation of gram-positive bacteria was only slightly affected by the presence of solid particles. Inactivation was found to follow first-order kinetics regarding bacteria population and was not affected significantly by the wastewater quality. Ultrasound irradiation at 4000kJ/L specific nominal energy and in the presence of 5g/L TiO(2) achieved less than 10(3) CFU/100mL total coliforms, thus meeting USEPA quality standards for wastewater reuse. PMID:19131265

  15. Potential Role for Telavancin in Bacteremic Infections Due to Gram-Positive Pathogens: Focus on Staphylococcus aureus

    PubMed Central

    Corey, G. Ralph; Rubinstein, Ethan; Stryjewski, Martin E.; Bassetti, Matteo; Barriere, Steven L.

    2015-01-01

    Staphylococcus aureus bacteremia (SAB) is one of the most common serious bacterial infections and the most frequent invasive infection due to methicillin-resistant S. aureus (MRSA). Treatment is challenging, particularly for MRSA, because of limited treatment options. Telavancin is a bactericidal lipoglycopeptide antibiotic that is active against a range of clinically relevant gram-positive pathogens including MRSA. In experimental animal models of sepsis telavancin was shown to be more effective than vancomycin. In clinically evaluable patients enrolled in a pilot study of uncomplicated SAB, cure rates were 88% for telavancin and 89% for standard therapy. Among patients with infection due to only gram-positive pathogens enrolled in the 2 phase 3 studies of telavancin for treatment of hospital-acquired pneumonia, cure rates for those with bacteremic S. aureus pneumonia were 41% (9/22, telavancin) and 40% (10/25, vancomycin) with identical mortality rates. These data support further evaluation of telavancin in larger, prospective studies of SAB. PMID:25472944

  16. Gram-Positive and Gram-Negative Bacteria Do Not Trigger Monocytic Cytokine Production through Similar Intracellular Pathways

    PubMed Central

    Rabehi, Lila; Irinopoulou, Théano; Cholley, Béatrice; Haeffner-Cavaillon, Nicole; Carreno, Marie-Paule

    2001-01-01

    Toll-like receptors (TLRs) are involved in human monocyte activation by lipopolysaccharide (LPS) and Staphylococcus aureus Cowan (SAC), suggesting that gram-positive and gram-negative bacteria may trigger similar intracellular events. Treatment with specific kinase inhibitors prior to cell stimulation dramatically decreased LPS-induced cytokine production. Blocking of the p38 pathway prior to LPS stimulation decreased interleukin-1α (IL-1α), IL-1ra, and tumor necrosis factor alpha (TNF-α) production, whereas blocking of the ERK1/2 pathways inhibited IL-1α, IL-1β, and IL-1ra but not TNF-α production. When cells were stimulated by SAC, inhibition of the p38 pathway did not affect cytokine production, whereas only IL-1α production was decreased in the presence of ERK kinase inhibitor. We also demonstrated that although LPS and SAC have been shown to bind to CD14 before transmitting signals to TLR4 and TLR2, respectively, internalization of CD14 occurred only in monocytes triggered by LPS. Pretreatment of the cells with SB203580, U0126, or a mixture of both inhibitors did not affect internalization of CD14. Altogether, these results suggest that TLR2 signaling does not involve p38 mitogen-activated protein kinase signaling pathways, indicating that divergent pathways are triggered by gram-positive and gram-negative bacteria, thereby inducing cytokine production. PMID:11402003

  17. Biosynthesis of Auxin by the Gram-Positive Phytopathogen Rhodococcus fascians Is Controlled by Compounds Specific to Infected Plant Tissues

    PubMed Central

    Vandeputte, Olivier; Öden, Sevgi; Mol, Adeline; Vereecke, Danny; Goethals, Koen; El Jaziri, Mondher; Prinsen, Els

    2005-01-01

    The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. We show here for the first time that R. fascians produces and secretes the auxin indole-3-acetic acid. Interestingly, whereas noninfected-tobacco extracts have no effect, indole-3-acetic acid synthesis is highly induced in the presence of infected-tobacco extracts when tryptophan is not limiting. Indole-3-acetic acid production by a plasmid-free strain shows that the biosynthetic genes are located on the bacterial chromosome, although plasmid-encoded genes contribute to the kinetics and regulation of indole-3-acetic acid biosynthesis. The indole-3-acetic acid intermediates present in bacterial cells and secreted into the growth media show that the main biosynthetic route used by R. fascians is the indole-3-pyruvic acid pathway with a possible rate-limiting role for indole-3-ethanol. The relationship between indole-3-acetic acid production and the symptoms induced by R. fascians is discussed. PMID:15746315

  18. Novel sigmaB regulation modules of Gram-positive bacteria involve the use of complex hybrid histidine kinases.

    PubMed

    de Been, Mark; Francke, Christof; Siezen, Roland J; Abee, Tjakko

    2011-01-01

    A common bacterial strategy to cope with stressful conditions is the activation of alternative sigma factors that control specific regulons enabling targeted responses. In the human pathogen Bacillus cereus, activation of the major stress-responsive sigma factor σ(B) is controlled by a signalling route that involves the multi-sensor hybrid histidine kinase RsbK. RsbK-type kinases are not restricted to the B. cereus group, but occur in a wide variety of other bacterial species, including members of the the low-GC Gram-positive genera Geobacillus and Paenibacillus as well as the high-GC actinobacteria. Genome context and protein sequence analyses of 118 RsbK homologues revealed extreme variability in N-terminal sensory as well as C-terminal regulatory domains and suggested that RsbK-type kinases are subject to complex fine-tuning systems, including sensitization and desensitization via methylation and demethylation within the helical domain preceding the H-box. The RsbK-mediated stress-responsive sigma factor activation mechanism that has evolved in B. cereus and the other species differs markedly from the extensively studied and highly conserved RsbRST-mediated σ(B) activation route found in Bacillus subtilis and other low-GC Gram-positive bacteria. Implications for future research on sigma factor control mechanisms are presented and current knowledge gaps are briefly discussed. PMID:21051490

  19. Neither Single nor a Combination of Routine Laboratory Parameters can Discriminate between Gram-positive and Gram-negative Bacteremia

    PubMed Central

    Ratzinger, Franz; Dedeyan, Michel; Rammerstorfer, Matthias; Perkmann, Thomas; Burgmann, Heinz; Makristathis, Athanasios; Dorffner, Georg; Loetsch, Felix; Blacky, Alexander; Ramharter, Michael

    2015-01-01

    Adequate early empiric antibiotic therapy is pivotal for the outcome of patients with bloodstream infections. In clinical practice the use of surrogate laboratory parameters is frequently proposed to predict underlying bacterial pathogens; however there is no clear evidence for this assumption. In this study, we investigated the discriminatory capacity of predictive models consisting of routinely available laboratory parameters to predict the presence of Gram-positive or Gram-negative bacteremia. Major machine learning algorithms were screened for their capacity to maximize the area under the receiver operating characteristic curve (ROC-AUC) for discriminating between Gram-positive and Gram-negative cases. Data from 23,765 patients with clinically suspected bacteremia were screened and 1,180 bacteremic patients were included in the study. A relative predominance of Gram-negative bacteremia (54.0%), which was more pronounced in females (59.1%), was observed. The final model achieved 0.675 ROC-AUC resulting in 44.57% sensitivity and 79.75% specificity. Various parameters presented a significant difference between both genders. In gender-specific models, the discriminatory potency was slightly improved. The results of this study do not support the use of surrogate laboratory parameters for predicting classes of causative pathogens. In this patient cohort, gender-specific differences in various laboratory parameters were observed, indicating differences in the host response between genders. PMID:26522966

  20. Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria

    PubMed Central

    Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Yadav, Anand

    2013-01-01

    Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50 μL leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3 mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0 mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

  1. Neofiscalin A and fiscalin C are potential novel indole alkaloid alternatives for the treatment of multidrug-resistant Gram-positive bacterial infections.

    PubMed

    Bessa, Lucinda J; Buttachon, Suradet; Dethoup, Tida; Martins, Rosário; Vasconcelos, Vitor; Kijjoa, Anake; Martins da Costa, Paulo

    2016-08-01

    Ten indole alkaloids were obtained from the marine sponge-associated fungus Neosartorya siamensis KUFA 0017. We studied the antimicrobial properties of these and of three other compounds previously isolated from the soil fungus N. siamensis KUFC 6349. Only neofiscalin A showed antimicrobial activity against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE); with a minimum inhibitory concentration (MIC) of 8 μg mL(-1) against both strains. Another compound, fiscalin C, presented synergistic activity against MRSA when combined with oxacillin, although alone showed no antibacterial effect. Moreover, neofiscalin A, when present at sub-MICs, hampered the ability of both MRSA and VRE strains to form a biofilm. Additionally, the biofilm inhibitory concentration values of neofiscalin A against the MRSA and VRE isolates were 96 and 80 μg mL(-1), respectively. At a concentration of 200 μg mL(-1), neofiscalin A was able to reduce the metabolic activity of the biofilms by ∼50%. One important fact is that our results also showed that neofiscalin A had no cytotoxicity against a human brain capillary endothelial cell line. PMID:27268269

  2. Biomineralization of carbonates by Marinococcus albus and Marinococcus halophilus isolated from the Salar de Atacama (Chile).

    PubMed

    Rivadeneyra, M A; Delgado, G; Soriano, M; Ramos-Cormenzana, A; Delgado, R

    1999-07-01

    We studied the precipitation of carbonates in 17 strains of moderately halophilic, Gram-positive cocci belonging to two species: Marinococcus halophilus and Marinococcus albus, isolated from the Salar de Atacama (Chile). They were cultivated in solid and liquid laboratory media for 42 days at salt concentrations (wt/vol) of 3%, 7.5%, 15%, and 20%. The bioliths precipitated were studied by X-ray diffraction and scanning electron microscopy. M. halophilus formed crystals at each of the salt concentrations, with a maximum number of strains capable of precipitating carbonates at 7.5% and 15% salt concentrations. M. albus did not precipitate at 20% and showed a maximum at 7.5%. This behavior is similar to that of other gram-positive bacteria and differs from that found in gram-negative bacteria. The bioliths precipitated were spherical, generally isolated, with a size of 10-100 microm, varying with salinity. They were of magnesium calcite (CO3 Ca1-x Mgx) with Mg content increasing with increasing salinity and Mg/Ca molar ratio of the culture medium. These results demonstrate the active role played by M. halophilus and M. albus in the precipitation of carbonates. PMID:10387118

  3. Targeting agr- and agr-Like Quorum Sensing Systems for Development of Common Therapeutics to Treat Multiple Gram-Positive Bacterial Infections

    PubMed Central

    Gray, Brian; Hall, Pamela; Gresham, Hattie

    2013-01-01

    Invasive infection by the Gram-positive pathogen Staphylococcus aureus is controlled by a four gene operon, agr that encodes a quorum sensing system for the regulation of virulence. While agr has been well studied in S. aureus, the contribution of agr homologues and analogues in other Gram-positive pathogens is just beginning to be understood. Intriguingly, other significant human pathogens, including Clostridium perfringens, Listeria monocytogenes, and Enterococcus faecalis contain agr or analogues linked to virulence. Moreover, other significant human Gram-positive pathogens use peptide based quorum sensing systems to establish or maintain infection. The potential for commonality in aspects of these signaling systems across different species raises the prospect of identifying therapeutics that could target multiple pathogens. Here, we review the status of research into these agr homologues, analogues, and other peptide based quorum sensing systems in Gram-positive pathogens as well as the potential for identifying common pathways and signaling mechanisms for therapeutic discovery. PMID:23598501

  4. Clinical Experience with Daptomycin for the Treatment of Gram-positive Infections in Children and Adolescents

    PubMed Central

    Syriopoulou, Vassiliki; Dailiana, Zoe; Dmitriy, Nisichenko; Utili, Riccardo; Pathan, Rashidkhan

    2016-01-01

    Background: This subgroup analysis of the European Cubicin Outcomes Registry Experience evaluated the safety and effectiveness of daptomycin in children and adolescent patients (<18 years). Methods: Clinical outcomes at the end of therapy were assessed as success (cured or improved), failure or nonevaluable. Safety was assessed for up to 30 days post treatment. Results: Eighty-one children and adolescent patients were included in this study. The most common primary infections were bacteremia (19.8%), complicated skin and soft-tissue infection (18.5%), osteomyelitis (13.6%), endocarditis (12.3%), foreign body/prosthetic infection (12.3%), uncomplicated skin and soft-tissue infection (9.9%) and other (13.6%). Daptomycin doses ranged from 4 to >10 mg/kg/day. Median duration of therapy was 12.5 (interquartile range, 7–25; mean, 16.7; standard deviation, 12.8) days. Staphylococcus aureus (46.7%) was the most commonly isolated pathogen (23.8% methicillin-resistant S. aureus). Forty-nine (60.5%) patients completed daptomycin therapy without further antibiotics, 27 (33.3%) switched to another antibiotic, 4 (4.9%) discontinued because of adverse events (AEs) and 1 (1.2%) discontinued because of other reason. Overall, 75 (92.6%; 95% confidence interval: 95.2–100.0%) patients achieved clinical success; 39 of 41 (95.1%) patients receiving daptomycin monotherapy and 36 of 40 (90.0%) patients receiving concomitant antibiotics. Six (7.4%) patients reported AEs, including 1 patient with increased blood creatine phosphokinase. Three (3.7%) patients had serious AEs; 1 (1.2%) had a serious AE possibly related to daptomycin. Conclusion: Daptomycin, alone or combined with other antibiotics and/or surgery, demonstrated high clinical success rates against a wide variety of infections and was well tolerated in children and adolescents. PMID:26849158

  5. Distinct Mechanisms Underlie Boosted Polysaccharide-Specific IgG Responses Following Secondary Challenge with Intact Gram-Negative versus Gram-Positive Extracellular Bacteria.

    PubMed

    Kar, Swagata; Arjunaraja, Swadhinya; Akkoyunlu, Mustafa; Pier, Gerald B; Snapper, Clifford M

    2016-06-01

    Priming of mice with intact, heat-killed cells of Gram-negative Neisseria meningitidis, capsular serogroup C (MenC) or Gram-positive group B Streptococcus, capsular type III (GBS-III) bacteria resulted in augmented serum polysaccharide (PS)-specific IgG titers following booster immunization. Induction of memory required CD4(+) T cells during primary immunization. We determined whether PS-specific memory for IgG production was contained within the B cell and/or T cell populations, and whether augmented IgG responses following booster immunization were also dependent on CD4(+) T cells. Adoptive transfer of purified B cells from MenC- or GBS-III-primed, but not naive mice resulted in augmented PS-specific IgG responses following booster immunization. Similar responses were observed when cotransferred CD4(+) T cells were from primed or naive mice. Similarly, primary immunization with unencapsulated MenC or GBS-III, to potentially prime CD4(+) T cells, failed to enhance PS-specific IgG responses following booster immunization with their encapsulated isogenic partners. Furthermore, in contrast to GBS-III, depletion of CD4(+) T cells during secondary immunization with MenC or another Gram-negative bacteria, Acinetobacter baumannii, did not inhibit augmented PS-specific IgG booster responses of mice primed with heat-killed cells. Also, in contrast with GBS-III, booster immunization of MenC-primed mice with isolated MenC-PS, a TI Ag, or a conjugate of MenC-PS and tetanus toxoid elicited an augmented PS-specific IgG response similar to booster immunization with intact MenC. These data demonstrate that memory for augmented PS-specific IgG booster responses to Gram-negative and Gram-positive bacteria is contained solely within the B cell compartment, with a differential requirement for CD4(+) T cells for augmented IgG responses following booster immunization. PMID:27183619

  6. Plants used in Guatemala for the treatment of respiratory diseases. 1. Screening of 68 plants against gram-positive bacteria.

    PubMed

    Caceres, A; Alvarez, A V; Ovando, A E; Samayoa, B E

    1991-02-01

    Respiratory ailments are important causes of morbidity and mortality in developing countries. Ethnobotanical surveys and literature reviews conducted in Guatemala during 1986-88 showed that 234 plants from 75 families, most of them of American origin, have been used for the treatment of respiratory ailments. Three Gram-positive bacteria causing respiratory infections (Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes) were used to screen 68 of the most commonly used plants for activity. Twenty-eight of these (41.2%) inhibited the growth of one or more of the bacteria tested. Staphylococcus aureus was inhibited by 18 of the plant extracts, while 7 extracts were effective against Streptococcus pyogenes. Plants of American origin which exhibited antibacterial activity were: Gnaphalium viscosum, Lippia alba, Lippia dulcis, Physalis philadelphica, Satureja brownei, Solanum nigrescens and Tagetes lucida. These preliminary in vitro results provide scientific basis for the use of these plants against bacterial respiratory infections. PMID:2023428

  7. Differential effects of gram-positive and gram-negative bacterial products on morphine induced inhibition of phagocytosis

    PubMed Central

    Jana, Ninkovic; Vidhu, Anand; Raini, Dutta; Zhang, Li; Saluja, Anuj; Meng, Jingjing; Lisa, Koodie; Santanu, Banerjee; Sabita, Roy

    2016-01-01

    Opioid drug abusers have a greater susceptibility to gram positive (Gram (+)) bacterial infections. However, the mechanism underlying opioid modulation of Gram (+) versus Gram (−) bacterial clearance has not been investigated. In this study, we show that opioid treatment resulted in reduced phagocytosis of Gram (+), when compared to Gram (−) bacteria. We further established that LPS priming of chronic morphine treated macrophages leads to potentiated phagocytosis and killing of both Gram (+) and Gram (−) bacteria in a P-38 MAP kinase dependent signaling pathway. In contrast, LTA priming lead to inhibition of both phagocytosis and bacterial killing. This study demonstrates for the first time the differential effects of TLR4 and TLR2 agonists on morphine induced inhibition of phagocytosis. Our results suggest that the incidence and severity of secondary infections with Gram (+) bacteria would be higher in opioid abusers. PMID:26891899

  8. Arginine Patch Predicts the RNA Annealing Activity of Hfq from Gram-Negative and Gram-Positive Bacteria.

    PubMed

    Zheng, Amy; Panja, Subrata; Woodson, Sarah A

    2016-06-01

    The Sm-protein Hfq facilitates interactions between small non-coding RNA (sRNA) and target mRNAs. In enteric Gram-negative bacteria, Hfq is required for sRNA regulation, and hfq deletion results in stress intolerance and reduced virulence. By contrast, the role of Hfq in Gram-positive is less established and varies among species. The RNA binding and RNA annealing activity of Hfq from Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Bacillus subtilis, and Staphylococcus aureus were compared using minimal RNAs and fluorescence spectroscopy. The results show that RNA annealing activity increases with the number of arginines in a semi-conserved patch on the rim of the Hfq hexamer and correlates with the previously reported requirement for Hfq in sRNA regulation. Thus, the amino acid sequence of the arginine patch can predict the chaperone function of Hfq in sRNA regulation in different organisms. PMID:27049793

  9. Armadillidin: a novel glycine-rich antibacterial peptide directed against gram-positive bacteria in the woodlouse Armadillidium vulgare (Terrestrial Isopod, Crustacean).

    PubMed

    Herbinière, Juline; Braquart-Varnier, Christine; Grève, Pierre; Strub, Jean-Marc; Frère, Jacques; Van Dorsselaer, Alain; Martin, Gilbert

    2005-01-01

    We report the isolation and the characterization of a novel antibacterial peptide from hemocytes of the woodlouse Armadillidium vulgare, naturally infected or uninfected by Wolbachia, an intracellular Gram-negative bacterium. This molecule displays antibacterial activity against Gram-positive bacteria despite its composition which classes it into the glycine-rich antibacterial peptide family, usually directed against fungi and Gram-negative bacteria. The complete sequence was determined by a combination of Edman degradation, mass spectrometry and cDNA cloning using a hemocyte library. The mature peptide (53 residues) has a 5259 Da molecular mass and is post-translationally modified by a C-terminal amidation. This peptide is characterized by a high level of glycine (47%) and a fivefold repeated motif GGGFH(R/S). As no evident sequence homology to other hitherto described antibacterial peptides has been found out, this antibacterial peptide was named armadillidin. Armadillidin is constitutively expressed in hemocytes and appears to be specific of A. vulgare. PMID:15752546

  10. Gram-negative and gram-positive antibacterial properties of the whole plant extract of willow herb (Epilobium angustifolium).

    PubMed

    Bartfay, Wally J; Bartfay, Emma; Johnson, Julia Green

    2012-01-01

    The emergence of new pathogens and the increase in the number of multidrug-resistant strains in well-established pathogens during the past decade represent a growing public health concern globally. With the current lack of research and development of new antibiotics by large pharmaceutical companies due to poor financial returns, new alternatives need to be explored including natural herbal or plant-based extracts with reported antibacterial properties. Willow herb (Epilobium angustifolium) preparations have been used in traditional aboriginal and folk medicine preparations externally as an antiphlogistic to treat prostate and gastrointestinal disorders and as an antiseptic to treat infected wounds. The authors hypothesized that a whole plant extract of willow herb would exhibit antimicrobial properties on a variety of both Gram-positive and gram-negative bacteria in culture. The authors found that, in comparison to growth controls, willow herb extract significantly inhibited the growth of Micrococcus luteus (p < .01), Staphylococcus aureus (p < .05), Escherichia coli (p < .001), and Pseudomonas aeruginosa (p < .001). They also found that willow herb extract inhibited the growth of bacteria in culture more effectively than vancomycin (p < .05) or tetracycline (p < .004). These results provide preliminary support for the traditional folkloric claim that the plant willow herb possesses antibacterial properties against a variety of gram-positive and gram-negative bacteria. Given that whole plant extract was utilized for this study, further investigations are warranted to determine which specific part of the plant (i.e., leaves, stem, roots, and flowers) possess the antibacterial properties. PMID:21208973

  11. Oral pristinamycin for the treatment of resistant Gram-positive infections in patients with cancer: Evaluation of clinical outcomes.

    PubMed

    Teng, J C; Lingaratnam, S M; Trubiano, J A; Thursky, K A; Slavin, M A; Worth, L J

    2016-05-01

    Pristinamycin has been used to treat a range of Gram-positive infections, but reported experience in patients with malignancy is limited. This study aimed to evaluate the use of pristinamycin in patients with cancer at an Australian centre. All patients commenced on oral pristinamycin therapy at the Peter MacCallum Cancer Centre between January 2005 and December 2014 were identified using the hospital pharmacy dispensing system. Information on demographics, co-morbidities, cancer diagnosis, infection characteristics, pristinamycin regimen, pristinamycin tolerability and outcomes was collected. The median duration of follow-up was 398 days. In total, 26 patients received pristinamycin, with median age of 61 years and a male predominance (65%). Underlying diagnoses were haematological malignancies (50%) and solid tumours (50%). Pathogens included 13 meticillin-resistant Staphylococcus aureus, 6 vancomycin-resistant Enterococcus faecium, 4 meticillin-resistant Staphylococcus epidermidis, 2 meticillin-susceptible S. aureus and 1 vancomycin-susceptible E. faecium. Infection sites were osteomyelitis (6), skin and soft-tissue (4), intra-abdominal/pelvic abscess (4), bloodstream (3), empyema (3), endocarditis/endovascular (3), prosthesis-related infection (2) and epididymo-orchitis (1). One patient ceased pristinamycin due to nausea. Regarding outcome, 13 patients (50%) were cured of infection, 8 (31%) had suppression and 5 (19%) had relapse. Relapses included 1 endovascular infection, 2 episodes of osteomyelitis, 1 pelvic abscess and 1 skin and soft-tissue infection. Overall, 81% of patients achieved cure or suppression of antibiotic-resistant or complex Gram-positive infections, consistent with published experience in non-cancer populations. A favourable tolerability profile makes oral pristinamycin a viable treatment option, particularly in settings where outpatient management of cancer is the objective. PMID:27089829

  12. The opening of the SPP1 bacteriophage tail, a prevalent mechanism in Gram-positive-infecting siphophages.

    PubMed

    Goulet, Adeline; Lai-Kee-Him, Joséphine; Veesler, David; Auzat, Isabelle; Robin, Gautier; Shepherd, Dale A; Ashcroft, Alison E; Richard, Eric; Lichière, Julie; Tavares, Paulo; Cambillau, Christian; Bron, Patrick

    2011-07-15

    The SPP1 siphophage uses its long non-contractile tail and tail tip to recognize and infect the Gram-positive bacterium Bacillus subtilis. The tail-end cap and its attached tip are the critical components for host recognition and opening of the tail tube for genome exit. In the present work, we determined the cryo-electron microscopic (cryo-EM) structure of a complex formed by the cap protein gp19.1 (Dit) and the N terminus of the downstream protein of gp19.1 in the SPP1 genome, gp21(1-552) (Tal). This complex assembles two back-to-back stacked gp19.1 ring hexamers, interacting loosely, and two gp21(1-552) trimers interacting with gp19.1 at both ends of the stack. Remarkably, one gp21(1-552) trimer displays a "closed" conformation, whereas the second is "open" delineating a central channel. The two conformational states dock nicely into the EM map of the SPP1 cap domain, respectively, before and after DNA release. Moreover, the open/closed conformations of gp19.1-gp21(1-552) are consistent with the structures of the corresponding proteins in the siphophage p2 baseplate, where the Tal protein (ORF16) attached to the ring of Dit (ORF15) was also found to adopt these two conformations. Therefore, the present contribution allowed us to revisit the SPP1 tail distal-end architectural organization. Considering the sequence conservation among Dit and the N-terminal region of Tal-like proteins in Gram-positive-infecting Siphoviridae, it also reveals the Tal opening mechanism as a hallmark of siphophages probably involved in the generation of the firing signal initiating the cascade of events that lead to phage DNA release in vivo. PMID:21622577

  13. Nanoemulsion Therapy for Burn Wounds Is Effective as a Topical Antimicrobial Against Gram-Negative and Gram-Positive Bacteria.

    PubMed

    Dolgachev, Vladislav A; Ciotti, Susan M; Eisma, Rone; Gracon, Stephen; Wilkinson, J Erby; Baker, James R; Hemmila, Mark R

    2016-01-01

    The aim of this study is to investigate the antimicrobial efficacy of two different nanoemulsion (NE) formulations against Gram-positive and Gram-negative bacteria in an in vivo rodent scald burn model. Male Sprague-Dawley rats were anesthetized and received a partial-thickness scald burn. Eight hours after burn injury, the wound was inoculated with 1 × 10(8) colony-forming units of Pseudomonas aeruginosa or Staphylococcus aureus. Treatment groups consisted of two different NE formulations (NB-201 and NB-402), NE vehicle, or saline. Topical application of the treatment was performed at 16 and 24 hours after burn injury. Animals were killed 32 hours after burn injury, and skin samples were obtained for quantitative wound culture and determination of dermal inflammation markers. In a separate set of experiments, burn wound progression was measured histologically after 72 hours of treatment. Both NE formulations (NB-201 and NB-402) significantly reduced burn wound infections with either P. aeruginosa or S. aureus and decreased median bacterial counts at least three logs when compared with animals with saline applications (p < .0001). NB-201 and NB-402 also decreased dermal neutrophil recruitment and sequestration into the wound as measured by myeloperoxidase (MPO) assay and histopathology (p < .05). In addition, there was a decrease in the proinflammatory dermal cytokines (interleukin 1-beta [IL-1β], IL-6, and tumor necrosis factor alpha [TNF-α]) and the neutrophil chemoattractants CXCL1 and CXCL2. Using histologic examination, it was found that both NB-201 and NB-402 appeared to suppress burn wound progression 72 hours after injury. Topically applied NB-201 and NB-402 are effective in decreasing Gram-positive and Gram-negative bacteria growth in burn wounds, reducing inflammation, and abrogating burn wound progression. PMID:26182074

  14. Differential sensitivity of aerobic gram-positive and gram-negative microorganisms to 2,4,6-trinitrotoluene (TNT) leads to dissimilar growth and TNT transformation: Results of soil and pure culture studies

    SciTech Connect

    Fuller, M.E.; Manning, J.F. Jr.

    1996-07-30

    The effects of 2,4,6-trinitrotoluene (TNT) on indigenous soil populations and pure bacterial cultures were examined. The number of colony-forming units (CFU) appearing when TNT-contaminated soil was spread on 0.3% molasses plates decreased by 50% when the agar was amended with 67 {mu}g TNT mL{sup -1}, whereas a 99% reduction was observed when uncontaminated soil was plated. Furthermore, TNT-contaminated soil harbored a greater number of organisms able to grow on plates amended with greater than 10 {mu}g TNT mL{sup -1}. The percentage of gram-positive isolates was markedly less in TNT-contaminated soil (7%; 2 of 30) than in uncontaminated soil (61%; 20 of 33). Pseudomonas aeruginosa, Pseudomonas corrugate, Pseudomonasfluorescens and Alcaligenes xylosoxidans made up the majority of the gram-negative isolates from TNT-contaminated soil. Gram-positive isolates from both soils demonstrated marked growth inhibition when greater than 8-16 {mu}g TNT mL{sup -1} was present in the culture media. Most pure cultures of known aerobic gram-negative organisms readily degraded TNT and evidenced net consumption of reduced metabolites. However, pure cultures of aerobic gram-positive bacteria were sensitive to relatively low concentrations of TNT as indicated by the 50% reduction in growth and TNT transformation which was observed at approximately 10 {mu}g TNT mL{sup -1}. Most non-sporeforming gram-positive organisms incubated in molasses media amended with 80 {mu}g TNT mL{sup -1} or greater became unculturable, whereas all strains tested remained culturable when incubated in mineral media amended with 98 {mu}g TNT mL{sup -1}, indicating that TNT sensitivity is likely linked to cell growth. These results indicate that gram-negative organisms are most likely responsible for any TNT transformation in contaminated soil, due to their relative insensitivity to high TNT concentrations and their ability to transform TNT.

  15. Induction of nitric oxide production by polyosides from the cell walls of Streptococcus mutans OMZ 175, a gram-positive bacterium, in the rat aorta.

    PubMed Central

    Martin, V; Kleschyov, A L; Klein, J P; Beretz, A

    1997-01-01

    The cardiovascular dysfunctions associated with septic shock induced by gram-negative or gram-positive bacteria (gram-positive or gram-negative septic shock) are comparable. In gram-negative septic shock, lipopolysaccharide (LPS) induces nitric oxide (NO) synthase, which contributes to the vascular hypotension and hyporeactivity to vasoconstrictors. The role of NO in gram-positive septic shock and the nature of the bacterial wall components responsible for the vascular effects of gram-positive bacteria are not well known. This study investigated the vascular effects of cell wall serotype polyosides, rhamnose glucose polymers (RGPs), from Streptococcus mutans, in comparison with lipoteichoic acid (LTA) from Staphylococcus aureus, on the induction of NO synthase activity in the rat aorta. We show that 10 microg of both RGPs and LTA per ml induced hyporeactivity to noradrenaline, L-arginine-induced relaxation, increases of 2.2- and 7.8-fold, respectively, of cyclic GMP production, and increases of 7- and 12-fold in nitrite release. All of these effects appeared after several hours of incubation and were inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase. Electron paramagnetic resonance spin trapping experiments demonstrated directly that RGPs and LTA induced NO overproduction (four- to eightfold, respectively) in rat aortic rings; this production was inhibited by L-NAME and prevented by dexamethasone. These results demonstrate directly the induction of NO production in vascular tissue by LTA and show that another, chemically different component of gram-positive bacteria can also have these properties. This result suggests that different components of the gram-positive bacterial wall could be implicated in the genesis of cardiovascular dysfunctions observed in gram-positive septic shock. PMID:9169734

  16. Draft Genome Sequence of Branchiibius sp. NY16-3462-2, Isolated from a Mixed Clinical Sample.

    PubMed

    Lapierre, Pascal; Halse, Tanya A; Shea, Joseph; Escuyer, Vincent E; Musser, Kimberlee A

    2016-01-01

    Here, we report the release of a draft genome assembly of a Gram-positive cocci Branchiibius sp. NY16-3462-2 with a high-GC content, sequenced from a mixed clinical sample containing Mycobacterium tuberculosis This genome is the first publicly available sequence from a representative of the genus Branchiibius. PMID:27174280

  17. Draft Genome Sequence of Branchiibius sp. NY16-3462-2, Isolated from a Mixed Clinical Sample

    PubMed Central

    Halse, Tanya A.; Shea, Joseph; Escuyer, Vincent E.; Musser, Kimberlee A.

    2016-01-01

    Here, we report the release of a draft genome assembly of a Gram-positive cocci Branchiibius sp. NY16-3462-2 with a high-GC content, sequenced from a mixed clinical sample containing Mycobacterium tuberculosis. This genome is the first publicly available sequence from a representative of the genus Branchiibius. PMID:27174280

  18. Clinical significance of coryneform Gram-positive rods from blood identified by MALDI-TOF mass spectrometry and their susceptibility profiles - a retrospective chart review.

    PubMed

    Mushtaq, Ammara; Chen, Derrick J; Strand, Gregory J; Dylla, Brenda L; Cole, Nicolynn C; Mandrekar, Jayawant; Patel, Robin

    2016-07-01

    With the advent of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), most Gram-positive rods (GPRs) are readily identified; however, their clinical relevance in blood cultures remains unclear. Herein, we assessed the clinical significance of GPRs isolated from blood and identified in the era of MALDI-TOF MS. A retrospective chart review of patients presenting to the Mayo Clinic, Rochester, MN, from January 1, 2013, to October 13, 2015, was performed. Any episode of a positive blood culture for a GPR was included. We assessed the number of bottles positive for a given isolate, time to positivity of blood cultures, patient age, medical history, interpretation of culture results by the healthcare team and whether infectious diseases consultation was obtained. We also evaluated the susceptibility profiles of a larger collection of GPRs tested in the clinical microbiology laboratory of the Mayo Clinic, Rochester, MN from January 1, 2013, to October 31, 2015. There were a total of 246 GPRs isolated from the blood of 181 patients during the study period. 56% (n = 101) were deemed contaminants by the healthcare team and were not treated; 33% (n = 59) were clinically determined to represent true bacteremia and were treated; and 8% (n = 14) were considered of uncertain significance, with patients prescribed treatment regardless. Patient characteristics associated with an isolate being treated on univariate analysis included younger age (P = 0.02), identification to the species level (P = 0.02), higher number of positive blood culture sets (P < 0.0001), lower time to positivity (P < 0.0001), immunosuppression (P = 0.03), and recommendation made by an infectious disease consultant (P = 0.0005). On multivariable analysis, infectious diseases consultation (P = 0.03), higher number of positive blood culture sets (P = 0.0005) and lower time to positivity (P = 0.03) were associated with an isolate being treated. 100, 83, 48 and 34% of GPRs

  19. Dynamic NETosis is Carried Out by Live Neutrophils in Human and Mouse Bacterial Abscesses and During Severe Gram-Positive Infection

    PubMed Central

    Yipp, Bryan G.; Petri, Björn; Salina, Davide; Jenne, Craig N.; Scott, Brittney N. V.; Zbytnuik, Lori D.; Pittman, Keir; Asaduzzaman, Muhammad; Wu, Kaiyu; Meijndert, H. Christopher; Malawista, Stephen E.; de Boisfleury Chevance, Anne; Zhang, Kunyan; Conly, John; Kubes, Paul

    2013-01-01

    Neutrophil extracellular traps (NETs) are released, as neutrophils die in vitro, in a process requiring hours, leaving a temporal gap for invasive microbes to exploit. Functional neutrophils undergoing NETosis have not been documented. During Gram-positive skin infections, we directly visualized live PMN in vivo rapidly releasing NETs, which prevented bacterial dissemination. NETosis occurred during crawling thereby casting large areas of NETs. NET-releasing PMN developed diffuse decondensed nuclei ultimately becoming devoid of DNA. Cells with abnormal nuclei displayed unusual crawling behavior highlighted by erratic pseudopods and hyperpolarization consistent with the nucleus being a fulcrum for crawling. A combined requirement of Tlr2 and complement mediated opsonization tightly regulated NET release. Additionally live human PMN developed decondensed nuclei and formed NETS in vivo and intact anuclear neutrophils were abundant in Gram-positive human abscesses. Therefore early in infection, non-cell death NETosis occurs in vivo during Gram-positive infection in mice and humans. PMID:22922410

  20. Structure-Activity Analysis of Gram-positive Bacterium-producing Lasso Peptides with Anti-mycobacterial Activity

    PubMed Central

    Inokoshi, Junji; Koyama, Nobuhiro; Miyake, Midori; Shimizu, Yuji; Tomoda, Hiroshi

    2016-01-01

    Lariatin A, an 18-residue lasso peptide encoded by the five-gene cluster larABCDE, displays potent and selective anti-mycobacterial activity. The structural feature is an N-terminal macrolactam ring, through which the C-terminal passed to form the rigid lariat-protoknot structure. In the present study, we established a convergent expression system by the strategy in which larA mutant gene-carrying plasmids were transformed into larA-deficient Rhodococcus jostii, and generated 36 lariatin variants of the precursor protein LarA to investigate the biosynthesis and the structure-activity relationships. The mutational analysis revealed that four amino acid residues (Gly1, Arg7, Glu8, and Trp9) in lariatin A are essential for the maturation and production in the biosynthetic machinery. Furthermore, the study on structure-activity relationships demonstrated that Tyr6, Gly11, and Asn14 are responsible for the anti-mycobacterial activity, and the residues at positions 15, 16 and 18 in lariatin A are critical for enhancing the activity. This study will not only provide a useful platform for genetically engineering Gram-positive bacterium-producing lasso peptides, but also an important foundation to rationally design more promising drug candidates for combatting tuberculosis. PMID:27457620

  1. Biocompatible Fe3O4 increases the efficacy of amoxicillin delivery against Gram-positive and Gram-negative bacteria.

    PubMed

    Grumezescu, Alexandru Mihai; Gestal, Monica Cartelle; Holban, Alina Maria; Grumezescu, Valentina; Vasile, Bogdan Stefan; Mogoantă, Laurențiu; Iordache, Florin; Bleotu, Coralia; Mogoșanu, George Dan

    2014-01-01

    This paper reports the synthesis and characterization of amoxicillin- functionalized magnetite nanostructures (Fe3O4@AMO), revealing and discussing several biomedical applications of these nanomaterials. Our results proved that 10 nm Fe3O4@AMO nanoparticles does not alter the normal cell cycle progression of cultured diploid cells, and an in vivo murine model confirms that the nanostructures disperse through the host body and tend to localize in particular sites and organs. The nanoparticles were found clustered especially in the lungs, kidneys and spleen, next to the blood vessels at this level, while being totally absent in the brain and liver, suggesting that they are circulated through the blood flow and have low toxicity. Fe3O4@AMO has the ability to be easily circulated through the body and optimizations may be done so these nanostructures cluster to a specific target region. Functionalized magnetite nanostructures proved a great antimicrobial effect, being active against both the Gram positive pathogen S. aureus and the Gram negative pathogen E. coli. The fabricated nanostructures significantly reduced the minimum inhibitory concentration (MIC) of the active drug. This result has a great practical relevance, since the functionalized nanostructures may be used for decreasing the therapeutic doses which usually manifest great severe side effects, when administrated in high doses. Fe3O4@AMO represents also a suitable approach for the development of new alternative strategies for improving the activity of therapeutic agents by targeted delivery and controlled release. PMID:24759068

  2. Silver-doped manganese dioxide and trioxide nanoparticles inhibit both gram positive and gram negative pathogenic bacteria.

    PubMed

    Kunkalekar, R K; Prabhu, M S; Naik, M M; Salker, A V

    2014-01-01

    Palladium, ruthenium and silver-doped MnO2 and silver doped Mn2O3 nanoparticles were synthesized by simple co-precipitation technique. SEM-TEM analysis revealed the nano-size of these synthesized samples. XPS data illustrates that Mn is present in 4+ and 3+ oxidation states in MnO2 and Mn2O3 respectively. Thermal analysis gave significant evidence for the phase changes with increasing temperature. Antibacterial activity of these synthesized nanoparticles on three Gram positive bacterial cultures (Staphylococcus aureus ATCC 6538, Streptococcus epidermis ATCC 12228, Bacillus subtilis ATCC 6633) and three Gram negative cultures (Escherichia coli ATCC 8739, Salmonella abony NCTC 6017 and Klebsiella pneumoniae ATCC 1003) was investigated using a disc diffusion method and live/dead assay. Only Ag-doped MnO2 and Ag-doped Mn2O3 nanoparticles showed antibacterial property against all six-test bacteria but Ag-doped MnO2 was found to be more effective than Ag-doped Mn2O3. PMID:24140741

  3. Regulation of transcription by eukaryotic-like serine-threonine kinases and phosphatases in Gram-positive bacterial pathogens

    PubMed Central

    Wright, David P; Ulijasz, Andrew T

    2014-01-01

    Bacterial eukaryotic-like serine threonine kinases (eSTKs) and serine threonine phosphatases (eSTPs) have emerged as important signaling elements that are indispensable for pathogenesis. Differing considerably from their histidine kinase counterparts, few eSTK genes are encoded within the average bacterial genome, and their targets are pleiotropic in nature instead of exclusive. The growing list of important eSTK/P substrates includes proteins involved in translation, cell division, peptidoglycan synthesis, antibiotic tolerance, resistance to innate immunity and control of virulence factors. Recently it has come to light that eSTK/Ps also directly modulate transcriptional machinery in many microbial pathogens. This novel form of regulation is now emerging as an additional means by which bacteria can alter their transcriptomes in response to host-specific environmental stimuli. Here we focus on the ability of eSTKs and eSTPs in Gram-positive bacterial pathogens to directly modulate transcription, the known mechanistic outcomes of these modifications, and their roles as an added layer of complexity in controlling targeted RNA synthesis to enhance virulence potential. PMID:25603430

  4. Two different primary oxidation mechanisms during biotransformation of thymol by gram-positive bacteria of the genera Nocardia and Mycobacterium.

    PubMed

    Hahn, Veronika; Sünwoldt, Katharina; Mikolasch, Annett; Schauer, Frieder

    2013-02-01

    Thymol has antibacterial, antifungal, insecticidal, and antioxidative properties which are the basis for the wide use of this compound in the cosmetic, food, and pharmaceutical industries. Although thymol is a ubiquitously occurring substance in the environment, data about its degradation and detoxification by bacteria are sparse. Here, we show the existence of two different pathways for the biotransformation of thymol by Nocardia cyriacigeorgica and Mycobacterium neoaurum which were described for the first time for gram-positive bacteria. The first pathway starts with hydroxylation of thymol to thymohydroquinone (2-isopropyl-5-methylbenzene-1,4-diol) with subsequent oxidation to thymobenzoquinone (2-isopropyl-5-methyl-1,4-benzoquinone). The second pathway involves hydroxylation of the methyl group followed by oxidation to 3-hydroxy-4-isopropylbenzoic acid, possibly via the aldehyde 3-hydroxy-4-isopropylbenzaldehyde. It is noteworthy that the branched side chain of thymol was not oxidized. Similarities and differences of these oxidation processes with those of the gram-negative bacterium Pseudomonas putida, fungi, and plants are discussed and, in addition, the toxicity of thymol towards N. cyriacigeorgica and M. neoaurum was tested. The experiments showed a temporary growth inhibition with 0.025 % thymol. This was explained by degradation of thymol and the formation of products which are less toxic than thymol itself. PMID:22828982

  5. Antimicrobial photodynamic efficiency of novel cationic porphyrins towards periodontal Gram-positive and Gram-negative pathogenic bacteria.

    PubMed

    Prasanth, Chandra Sekhar; Karunakaran, Suneesh C; Paul, Albish K; Kussovski, Vesselin; Mantareva, Vanya; Ramaiah, Danaboyina; Selvaraj, Leslie; Angelov, Ivan; Avramov, Latchezar; Nandakumar, Krishnankutty; Subhash, Narayanan

    2014-01-01

    The Gram-negative Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum are major causative agents of aggressive periodontal disease. Due to increase in the number of antibiotic-resistant bacteria, antimicrobial Photodynamic therapy (aPDT) seems to be a plausible alternative. In this work, photosensitization was performed on Gram-positive and Gram-negative bacteria in pure culture using new-age cationic porphyrins, namely mesoimidazolium-substituted porphyrin derivative (ImP) and pyridinium-substituted porphyrin derivative (PyP). The photophysical properties of both the sensitizers including absorption, fluorescence emission, quantum yields of the triplet excited states and singlet oxygen generation efficiencies were evaluated in the context of aPDT application. The studied porphyrins exhibited high ability to accumulate into bacterial cells with complete penetration into early stage biofilms. As compared with ImP, PyP was found to be more effective for photoinactivation of bacterial strains associated with periodontitis, without any signs of dark toxicity, owing to its high photocytotoxicity. PMID:24164211

  6. Inhibition of various gram-positive and gram-negative bacteria growth on selenium nanoparticle coated paper towels.

    PubMed

    Wang, Qi; Larese-Casanova, Philip; Webster, Thomas J

    2015-01-01

    There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns. PMID:25926733

  7. The structure of secondary cell wall polymers: how Gram-positive bacteria stick their cell walls together.

    PubMed

    Schäffer, Christina; Messner, Paul

    2005-03-01

    The cell wall of Gram-positive bacteria has been a subject of detailed chemical study over the past five decades. Outside the cytoplasmic membrane of these organisms the fundamental polymer is peptidoglycan (PG), which is responsible for the maintenance of cell shape and osmotic stability. In addition, typical essential cell wall polymers such as teichoic or teichuronic acids are linked to some of the peptidoglycan chains. In this review these compounds are considered as 'classical' cell wall polymers. In the course of recent investigations of bacterial cell surface layers (S-layers) a different class of 'non-classical' secondary cell wall polymers (SCWPs) has been identified, which is involved in anchoring of S-layers to the bacterial cell surface. Comparative analyses have shown considerable differences in chemical composition, overall structure and charge behaviour of these SCWPs. This review discusses the progress that has been made in understanding the structural principles of SCWPs, which may have useful applications in S-layer-based 'supramolecular construction kits' in nanobiotechnology. PMID:15758211

  8. Mobilizable Rolling-Circle Replicating Plasmids from Gram-Positive Bacteria: A Low-Cost Conjugative Transfer

    PubMed Central

    Fernández-López, Cris; Bravo, Alicia; Ruiz-Cruz, Sofía; Solano-Collado, Virtu; Garsin, Danielle A.; Lorenzo-Díaz, Fabián; Espinosa, Manuel

    2014-01-01

    Chapter summary Conjugation is a key mechanism for horizontal gene transfer in bacteria. Some plasmids are not self-transmissible but can be mobilized by functions encoded in trans provided by other auxiliary conjugative elements. Although the transfer efficiency of mobilizable plasmids is usually lower than that of conjugative elements, mobilizable plasmidsare more frequently found in nature. In this sense, replication and mobilization can be considered as important mechanisms influencing plasmid promiscuity. Here we review the present available information on two families of small mobilizable plasmids from Gram-positive bacteria that replicate via the rolling-circle mechanism. One of these families, represented by the streptococcal plasmid pMV158, is an interesting model since it contains a specific mobilization module (MOBV) that is widely distributed among mobilizable plasmids. We discuss a mechanism in which the promiscuity of the pMV158 replicon is based on the presence of two origins of lagging strand synthesis. The current strategies to assess plasmid transfer efficiency as well as to inhibit conjugative plasmid transfer are presented. Some applications of these plasmids as biotechnological tools are also reviewed. PMID:25606350

  9. A zebrafish intelectin ortholog agglutinates both Gram-negative and Gram-positive bacteria with binding capacity to bacterial polysaccharide.

    PubMed

    Chen, Lei; Yan, Jie; Sun, Weiping; Zhang, Yan; Sui, Chao; Qi, Jing; Du, Yijun; Feng, Lijun

    2016-08-01

    Intelectins are glycan-binding lectins found in various species including cephalochordates, urochordates, fish, amphibians and mammals. But their detailed functions are not well studied in zebrafish which is a good model to study native immunity. In this study, we cloned a zebrafish intelectin ortholog, zebrafish intelectin 2 (zITLN2), which contains a conserved fibrinogen-related domain (FReD) in the N-terminus and the unique intelectin domain in the C-terminus. We examined the tissue distribution of zITLN2 in adult zebrafish and found that zITLN2 was expressed in various organs with the highest level in intestine. Like amphioxus intelectins, zITLN2 expression was upregulated in adult zebrafish infected with Staphylococcus aureus with the highest expression level at 12 h after challenge. Recombinant zITLN2 protein expressed in E. coli was able to agglutinate both Gram-negative and Gram-positive bacteria to similar degrees in a calcium-dependent manner. Furthermore, recombinant zITLN2 bound lipopolysaccharide (LPS) and peptidoglycan (PGN) comparably. Our work on zITLN2 provided further information to understand functions of this new family of lectins and the innate immunity in vertebrates. PMID:27329687

  10. Antibacterial Activity of Stenotrophomonas maltophilia Endolysin P28 against both Gram-positive and Gram-negative Bacteria

    PubMed Central

    Dong, Hongling; Zhu, Chaoyang; Chen, Jingyi; Ye, Xing; Huang, Yu-Ping

    2015-01-01

    Maltocin P28 is a phage-tail like bacteriocin produced by Stenotrophomonas maltophilia P28. The ORF8 of maltocin P28 gene cluster is predicted to encode an endolysin and we name it endolysin P28. Sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. Endolysin P28 has the four consensus motifs as that of Escherichia coli phage lambda gpR. In this study, endolysin P28 was expressed in E. coli BL21 (DE3) and purified with a C-terminal oligo-histidine tag. The antibacterial activity of endolysin P28 increased as the temperature rose from 25 to 45°C. Thermostability assays showed that endolysin P28 was stable up to 50°C, while its residual activity was reduced by 55% after treatment at 70°C for 30 min. Acidity and high salinity could enhance its antibacterial activity. Endolysin P28 exhibited a broad antibacterial activity against 14 out of 16 tested Gram-positive and Gram-negative bacteria besides S. maltophilia. Moreover, it could effectively lyse intact Gram-negative bacteria in the absence of ethylenediaminetetraacetic acid as an outer membrane permeabilizer. Therefore, the characteristics of endolysin P28 make it a potential therapeutic agent against multi-drug-resistant pathogens. PMID:26635765

  11. Presence and dissemination of the multiresistance gene cfr in Gram-positive and Gram-negative bacteria.

    PubMed

    Shen, Jianzhong; Wang, Yang; Schwarz, Stefan

    2013-08-01

    The emergence of the multiresistance gene cfr in staphylococci is of global concern. In addition to conferring resistance to phenicols, lincosamides, pleuromutilins, streptogramin A antibiotics and selected 16-membered macrolides, the cfr gene also confers resistance to the oxazolidinone linezolid. Linezolid is a last-resort antimicrobial agent for the treatment of serious infections in humans caused by resistant Gram-positive bacteria. The cfr gene is often located on plasmids and several cfr-carrying plasmids have been described, which differ in their structure, their size and the presence of additional resistance genes. These plasmids are important vehicles that promote the spread of the cfr gene not only among bacteria of the same species, but also among those of different species and genera. Moreover, the cfr gene has been identified in close proximity to different insertion sequences, which most probably also play an important role in its dissemination. This review summarizes current knowledge on the genetic environment of the multiresistance gene cfr with particular reference to mobile genetic elements and co-located resistance genes that may support its emergence. PMID:23543608

  12. Inhibition of various gram-positive and gram- negative bacteria growth on selenium nanoparticle coated paper towels

    PubMed Central

    Wang, Qi; Larese-Casanova, Philip; Webster, Thomas J

    2015-01-01

    There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns. PMID:25926733

  13. Differential Targeting of the E-Cadherin/β-Catenin Complex by Gram-Positive Probiotic Lactobacilli Improves Epithelial Barrier Function

    PubMed Central

    Hummel, Stephanie; Veltman, Katharina; Cichon, Christoph; Sonnenborn, Ulrich

    2012-01-01

    The intestinal ecosystem is balanced by dynamic interactions between resident and incoming microbes, the gastrointestinal barrier, and the mucosal immune system. However, in the context of inflammatory bowel diseases (IBD), where the integrity of the gastrointestinal barrier is compromised, resident microbes contribute to the development and perpetuation of inflammation and disease. Probiotic bacteria have been shown to exert beneficial effects, e.g., enhancing epithelial barrier integrity. However, the mechanisms underlying these beneficial effects are only poorly understood. Here, we comparatively investigated the effects of four probiotic lactobacilli, namely, Lactobacillus acidophilus, L. fermentum, L. gasseri, and L. rhamnosus, in a T84 cell epithelial barrier model. Results of DNA microarray experiments indicating that lactobacilli modulate the regulation of genes encoding in particular adherence junction proteins such as E-cadherin and β-catenin were confirmed by quantitative reverse transcription-PCR (qRT-PCR). Furthermore, we show that epithelial barrier function is modulated by Gram-positive probiotic lactobacilli via their effect on adherence junction protein expression and complex formation. In addition, incubation with lactobacilli differentially influences the phosphorylation of adherence junction proteins and the abundance of protein kinase C (PKC) isoforms such as PKCδ that thereby positively modulates epithelial barrier function. Further insight into the underlying molecular mechanisms triggered by these probiotics might also foster the development of novel strategies for the treatment of gastrointestinal diseases (e.g., IBD). PMID:22179242

  14. Structure-Activity Analysis of Gram-positive Bacterium-producing Lasso Peptides with Anti-mycobacterial Activity

    NASA Astrophysics Data System (ADS)

    Inokoshi, Junji; Koyama, Nobuhiro; Miyake, Midori; Shimizu, Yuji; Tomoda, Hiroshi

    2016-07-01

    Lariatin A, an 18-residue lasso peptide encoded by the five-gene cluster larABCDE, displays potent and selective anti-mycobacterial activity. The structural feature is an N-terminal macrolactam ring, through which the C-terminal passed to form the rigid lariat-protoknot structure. In the present study, we established a convergent expression system by the strategy in which larA mutant gene-carrying plasmids were transformed into larA-deficient Rhodococcus jostii, and generated 36 lariatin variants of the precursor protein LarA to investigate the biosynthesis and the structure-activity relationships. The mutational analysis revealed that four amino acid residues (Gly1, Arg7, Glu8, and Trp9) in lariatin A are essential for the maturation and production in the biosynthetic machinery. Furthermore, the study on structure-activity relationships demonstrated that Tyr6, Gly11, and Asn14 are responsible for the anti-mycobacterial activity, and the residues at positions 15, 16 and 18 in lariatin A are critical for enhancing the activity. This study will not only provide a useful platform for genetically engineering Gram-positive bacterium-producing lasso peptides, but also an important foundation to rationally design more promising drug candidates for combatting tuberculosis.

  15. Transcriptional profiling of Gram-positive Arthrobacter in the phyllosphere: induction of pollutant degradation genes by natural plant phenolic compounds.

    PubMed

    Scheublin, Tanja R; Deusch, Simon; Moreno-Forero, Silvia K; Müller, Jochen A; van der Meer, Jan Roelof; Leveau, Johan H J

    2014-07-01

    Arthrobacter chlorophenolicus A6 is a Gram-positive, 4-chlorophenol-degrading soil bacterium that was recently shown to be an effective colonizer of plant leaf surfaces. The genetic basis for this phyllosphere competency is unknown. In this paper, we describe the genome-wide expression profile of A.chlorophenolicus on leaves of common bean (Phaseolus vulgaris) compared with growth on agar surfaces. In phyllosphere-grown cells, we found elevated expression of several genes known to contribute to epiphytic fitness, for example those involved in nutrient acquisition, attachment, stress response and horizontal gene transfer. A surprising result was the leaf-induced expression of a subset of the so-called cph genes for the degradation of 4-chlorophenol. This subset encodes the conversion of the phenolic compound hydroquinone to 3-oxoadipate, and was shown to be induced not only by 4-chlorophenol but also hydroquinone, its glycosylated derivative arbutin, and phenol. Small amounts of hydroquinone, but not arbutin or phenol, were detected in leaf surface washes of P.vulgaris by gas chromatography-mass spectrometry. Our findings illustrate the utility of genomics approaches for exploration and improved understanding of a microbial habitat. Also, they highlight the potential for phyllosphere-based priming of bacteria to stimulate pollutant degradation, which holds promise for the application of phylloremediation. PMID:24373130

  16. A Continuum of Anionic Charge: Structures and Functions of d-Alanyl-Teichoic Acids in Gram-Positive Bacteria†

    PubMed Central

    Neuhaus, Francis C.; Baddiley, James

    2003-01-01

    Teichoic acids (TAs) are major wall and membrane components of most gram-positive bacteria. With few exceptions, they are polymers of glycerol-phosphate or ribitol-phosphate to which are attached glycosyl and d-alanyl ester residues. Wall TA is attached to peptidoglycan via a linkage unit, whereas lipoteichoic acid is attached to glycolipid intercalated in the membrane. Together with peptidoglycan, these polymers make up a polyanionic matrix that functions in (i) cation homeostasis; (ii) trafficking of ions, nutrients, proteins, and antibiotics; (iii) regulation of autolysins; and (iv) presentation of envelope proteins. The esterification of TAs with d-alanyl esters provides a means of modulating the net anionic charge, determining the cationic binding capacity, and displaying cations in the wall. This review addresses the structures and functions of d-alanyl-TAs, the d-alanylation system encoded by the dlt operon, and the roles of TAs in cell growth. The importance of dlt in the physiology of many organisms is illustrated by the variety of mutant phenotypes. In addition, advances in our understanding of d-alanyl ester function in virulence and host-mediated responses have been made possible through targeted mutagenesis of dlt. Studies of the mechanism of d-alanylation have identified two potential targets of antibacterial action and provided possible screening reactions for designing novel agents targeted to d-alanyl-TA synthesis. PMID:14665680

  17. Pattern recognition receptors and interleukin-8 mediate effects of Gram-positive and Gram-negative bacteria on lung epithelial cell function

    PubMed Central

    Sorrentino, R; de Souza, P M; Sriskandan, S; Duffin, C; Paul-Clark, M J; Mitchell, J A

    2008-01-01

    Background and purpose: Lung epithelial cells express pattern recognition receptors, which react to bacteria. We have evaluated the effect of Gram-positive and Gram-negative bacteria on interleukin-8 (CXCL8) release from epithelial cells and the integrity of the epithelial barrier. Experimental approach: Primary cultures of human airway epithelial cells and the epithelial cell line A549 were used, and CXCL8 release was measured after exposure to Gram-negative or Gram-positive bacteria. Epithelial barrier function was assessed in monolayer cultures of A549 cells. Results: Gram-positive bacteria Staphylococcus aureus or Streptococcus pneumoniae, induced release of CXCL8 from human airway epithelial cells. These bacteria also disrupted barrier function in A549 cells, an effect mimicked by CXCL8 and blocked by specific binding antibodies to CXCL8. Gram–negative bacteria Escherichia coli or Pseudomonas aeruginosa induced greater release of CXCL8 than Gram-positive bacteria. However, Gram-negative bacteria did not affect epithelial barrier function directly, but prevented disruption induced by Gram-positive bacteria. These effects of Gram-negative bacteria on barrier function were mimicked by FK565, an agonist of the nucleotide-binding oligomerization domain 1 (NOD1) receptor, but not by the Toll-like receptor (TLR) 4 agonist bacterial lipopolysaccharide. Neither the Gram-negative bacteria nor FK565 blocked CXCL8 release. Conclusions: These data show differential functional responses induced by Gram-negative and Gram-positive bacteria in human lung epithelial cells. The NOD1 receptors may have a role in preventing disruption of the epithelial barrier in lung, during inflammatory states. PMID:18536738

  18. Characterization of Leuconostoc oenos Isolated from Oregon Wines †

    PubMed Central

    Izuagbe, Y. S.; Dohman, T. P.; Sandine, W. E.; Heatherbell, D. A.

    1985-01-01

    This study was designed to characterize isolates of Leuconostoc species from Oregon wines. Gram-positive cocci were isolated, and their biochemical properties and abilities to decompose malic acid were determined. All of the isolates were heterofermentative, catalase negative, and facultatively anaerobic and occurred in pairs and chains. They produced acid from glucose, fructose, mannose, ribose, cellobiose, trehalose, and salicin but not from sucrose or lactose. They did not produce ammonia from arginine or dextran from sucrose. They grew at pH values of less than 4 and in 10% ethanol. Most but not all strains produced lactic acid and carbon dioxide from malic acid, as determined by paper chromatography and respirometry, respectively. These malolactic bacteria were considered to be strains of Leuconostoc oenos. We compared these isolates with reference strains for relative growth at pH values of 4.0, 3.5, 3.0, and 2.8 at 22°C. The isolates were similar in their growth responses at the two highest pH levels. At pH 3.0 and 2.8, however, the strains failed to grow but revealed variable abilities to dissimilate malic acid. PMID:16346886

  19. [Microbiological isolates in patients with febrile neutropenia and hematological neoplasias].

    PubMed

    Figuera Esparza, M; Carballo, M; Silva, M; Figueredo, A; Avilán, J

    2006-09-01

    We studied the frequency of culture isolation, type of microorganism isolated and local pattern of resistance in 309 adult febrile neutropenic inpatients with hematological neoplasm, who were hospitalized between January 1998 and December 2003, in Caracas University Hospital (Hospital Universitario de Caracas), in Venezuela. There were 576 febrile neutropenic episodes. Organisms were isolated in 41% of 940 cultures. The most common organisms involved were gram-negative bacilli (48%), followed by gram-positive cocci (35.1%), fungal (11.5%) and other agents (5.4%). Coagulase-negative staphylococci (22.4%) and Escherichia coli (13.4%) were the most isolated; 58.5% of 479 agents isolated had an antibiogram; 62.2% of coagulase-negative staphylococci and 23.1% coagulase-positive staphylococci were oxacillin-resistant. We did not find any vancomycin-resistant organisms. The gram-negative antimicrobial sensitivity for imipenem was 96.2%, cefepime 81%, and ceftazidime 57.5%. Tazobactam-piperacillin and sulbactam-cefoperazone were tested in 26% of antibiograms and had activity of 57.1% and 77.5%, respectively. Fungi were not characterized. Betalactamases producing gram-negative bacilli were found. In general, micro-biological identification and local vigilance of antibacterial resistance pattern must be done routinely in these patients, in order to improve empiric therapy guidelines. PMID:17099792

  20. Does capillary racetrack-based enrichment reflect the diversity of uncultivated magnetotactic cocci in environmental samples?

    PubMed

    Lin, Wei; Tian, Lanxiang; Li, Jinhua; Pan, Yongxin

    2008-02-01

    The racetrack-based PCR approach is widely used in phylogenetic analysis of magnetotactic bacteria (MTB), which are isolated from environmental samples using the capillary racetrack method. To evaluate whether the capillary racetrack-based enrichment can truly reflect the diversity of MTB in the targeted environmental sample, phylogenetic diversity studies of MTB enriched from the Miyun lake near Beijing were carried out, using both the capillary racetrack-based PCR and a modified metagenome-based PCR approach. Magnetotactic cocci were identified in the studied sample using both approaches. Comparative studies showed that three clusters of magnetotactic cocci were revealed by the modified metagenome-based PCR approach, while only one of them (e.g. MYG-22 sequence) was detected by the racetrack-based PCR approach from the studied sample. This suggests that the result of capillary racetrack-based enrichment might have been biased by the magnetotaxis of magnetotactic bacteria. It appears that the metagenome-based PCR approach better reflects the original diversity of MTB in the environmental sample. PMID:18179585

  1. Rapid Discrimination of Gram-Positive and Gram-Negative Bacteria in Liquid Samples by Using NaOH-Sodium Dodecyl Sulfate Solution and Flow Cytometry

    PubMed Central

    Wada, Atsushi; Kono, Mari; Kawauchi, Sawako; Takagi, Yuri; Morikawa, Takashi; Funakoshi, Kunihiro

    2012-01-01

    Background For precise diagnosis of urinary tract infections (UTI), and selection of the appropriate prescriptions for their treatment, we explored a simple and rapid method of discriminating gram-positive and gram-negative bacteria in liquid samples. Methodology/Principal Findings We employed the NaOH-sodium dodecyl sulfate (SDS) solution conventionally used for plasmid extraction from Escherichia coli and the automated urine particle analyzer UF-1000i (Sysmex Corporation) for our novel method. The NaOH-SDS solution was used to determine differences in the cell wall structures between gram-positive and gram-negative bacteria, since the tolerance to such chemicals reflects the thickness and structural differences of bacterial cell walls. The UF-1000i instrument was used as a quantitative bacterial counter. We found that gram-negative bacteria, including E. coli, in liquid culture could easily be lysed by direct addition of equal volumes of NaOH-SDS solution. In contrast, Enterococcus faecalis, which is a gram-positive bacterium, could not be completely lysed by the solution. We then optimized the reaction time of the NaOH-SDS treatment at room temperature by using 3 gram-positive and 4 gram-negative bacterial strains and determined that the optimum reaction time was 5 min. Finally, in order to evaluate the generalizability of this method, we treated 8 gram-positive strains and 8 gram-negative strains, or 4 gram-positive and 4 gram-negative strains incubated in voluntary urine from healthy volunteers in the same way and demonstrated that all the gram-positive bacteria were discriminated quantitatively from gram negative bacteria using this method. Conclusions/Significance Using our new method, we could easily discriminate gram-positive and gram-negative bacteria in liquid culture media within 10 min. This simple and rapid method may be useful for determining the treatment course of patients with UTIs, especially for those without a prior history of UTIs. The method

  2. Transformation of the gram-positive bacterium Clavibacter xyli subsp. cynodontis by electroporation with plasmids from the IncP incompatibility group.

    PubMed Central

    Metzler, M C; Zhang, Y P; Chen, T A

    1992-01-01

    We report the transformation of a gram-positive bacterium, Clavibacter xyli subsp. cynodontis, with several plasmids in the IncP incompatibility group from gram-negative bacteria. Our results suggest that IncP plasmids may be transferable to other gram-positive organisms. After optimizing electroporation parameters, we obtained a maximum of 2 x 10(5) transformants per microgram of DNA. The availability of a transformation system for this bacteria will facilitate its use in indirectly expressing beneficial traits in plants. PMID:1624442

  3. Antimicrobial activity of cationic gemini surfactant containing an oxycarbonyl group in the lipophilic portion against gram-positive and gram-negative microorganisms.

    PubMed

    Tatsumi, Taiga; Imai, Yoshitane; Kawaguchi, Kakuhiro; Miyano, Naoko; Ikeda, Isao

    2014-01-01

    We evaluated the antimicrobial activities of a cationic Gemini surfactant, trans-1,4-bis[2-(alkanoyloxy)ethyldimethylammonio]-2-butene dichloride [II-m-2(t-butene)] and its derivatives against Gram-positive and Gram-negative microorganisms. The II-m-2(t-butene) compound was previously shown to have good surface activity and biodegradability. A dodecanoyloxy derivative (m = 12) of II-m-2(t-butene) showed excellent antimicrobial activity against Gram-positive Streptococcus aureus [minimum inhibitory concentration (MIC): 7.8 μg/mL] and Gram-negative Escherichia coli (MIC: 31.2 μg/mL). PMID:24420061

  4. Lactobacillus plantarum LB95 impairs the virulence potential of Gram-positive and Gram-negative food-borne pathogens in HT-29 and Vero cell cultures.

    PubMed

    Dutra, Virna; Silva, Ana Carla; Cabrita, Paula; Peres, Cidália; Malcata, Xavier; Brito, Luisa

    2016-01-01

    Listeria monocytogenes, Salmonella enterica and verocytotoxigenic Escherichia coli (VTEC) are amongst the most important agents responsible for food outbreaks occurring worldwide. In this work, two Lactobacillus spp. strains (LABs), Lactobacillus plantarum (LB95) and Lactobacillus paraplantarum (LB13), previously isolated from spontaneously fermenting olive brines, and two reference probiotic strains, Lactobacillus casei Shirota and Lactobacillus rhamnosus GG, were investigated for their ability to attenuate the virulence of the aforementioned pathogens using animal cell culture assays. In competitive exclusion assays, the relative percentages of adhesion and invasion of S. enterica subsp. enterica serovar Enteritidis were significantly reduced when the human HT-29 cell line was previously exposed to LB95. The relative percentage of invasion by Listeria monocytogenes was significantly reduced when HT-29 cells were previously exposed to LB95. In the cytotoxicity assays, the cell-free supernatant of the co-culture (CFSC)of VTEC with LB95 accounted for the lowest value obtained amongst the co-cultures of VTEC with LABs, and was significantly lower than the value obtained with the co-culture of VTEC with the two probiotic reference strains. The cytotoxicity of CFSC of VTEC with both LB95 and LB13 exhibited values not significantly different from the cell-free supernatant of the nonpathogenic E. coli B strain. Our results suggested that LB95 may be able to attenuate the virulence of Gram-positive and Gram-negative food-borne pathogens; together with other reported features of these strains, our data reveal their possible use in probiotic foods due to their interesting potential in preventing enteric infections in humans. PMID:26506821

  5. Adsorption and Fenton regeneration of SBA-15 for di-(2-ethylhexyl) phthalate leached from PVC sheets by Gram-positive strains LHM1 and LHM2

    NASA Astrophysics Data System (ADS)

    Hwang, S.; Latorre, I.; Caban, M.; Soto, B.; Montalvo-Rodríguez, R.; Hernández-Maldonado, A.

    2012-12-01

    Bioleaching of Di-(2-ethylhexyl) phthalate (DEHP) from PVC sheets was studied with newly isolated, Gram-positive strains LHM1 and LHM2 capable of growing on DEHP as the sole carbon source. According to 16S rRNA gene analysis, strains LHM1 and LHM2 were closely related (more than 97% similarity) to Chryseomicrobium imtechense MW 10(T) and Lysinibacillus fusiformis NBRC 15717(T), respectively. The biodeteriorated PVC sheets by the strains LHM1 and LHM2 had thicker biofilm development. Despite their metabolic capability of degrading DEHP as the sole carbon source, the strains LHM1 and LHM2 did not metabolize all DEHP leached out of the PVC sheets. Thermogravimetric analysis (TGA) showed that the biodeterioration by strains LHM1 and LHM2 resulted in less amount of and weakly bonded DEHP present in PVC sheets, in comparison to the virgin PVC sheet. Therefore, PVC biodeterioration by strains LHM1 and LHM2 might play an important role in stability of PVC sheets and fate and effect of leached DEHP on the environmental receptors. In response to this, an advanced adsorption with SBA-15 was assessed as a potential alternative DEHP remediation with arsenic as a co-contaminant. SBA-15 had an excellent arsenic adsorption showing >90% arsenic removal when arsenic was present as a singular contaminant. Adsorption effectiveness was irrelevant to the solid/liquid (S/L) ratio. However, when arsenic was present together with DEHP, arsenic adsorption to bare SBA-15 was reduced by 10 - 40%, with lesser S/L ratio having greater arsenic removal. On the contrary, bare SBA-15 only adsorbed ~30% of DEHP on average. When DEHP was present as a co-solute with arsenic, DEHP adsorption to bare SBA-15 was increased. For SBA-15 regeneration, adsorbed arsenic was recovered with EDTA elution, whereas adsorbed DEHP was destructed with Fenton oxidation.

  6. Acylation of SC4 dodecapeptide increases bactericidal potency against Gram-positive bacteria, including drug-resistant strains.

    PubMed Central

    Lockwood, Nathan A; Haseman, Judith R; Tirrell, Matthew V; Mayo, Kevin H

    2004-01-01

    We have conjugated dodecyl and octadecyl fatty acids to the N-terminus of SC4, a potently bactericidal, helix-forming peptide 12-mer (KLFKRHLKWKII), and examined the bactericidal activities of the resultant SC4 'peptide-amphiphile' molecules. SC4 peptide-amphiphiles showed up to a 30-fold increase in bactericidal activity against Gram-positive strains (Staphylococcus aureus, Streptococcus pyogenes and Bacillus anthracis), including S. aureus strains resistant to conventional antibiotics, but little or no increase in bactericidal activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Fatty acid conjugation improved endotoxin (lipopolysaccharide) neutralization by 3- to 6-fold. Although acylation somewhat increased lysis of human erythrocytes, it did not increase lysis of endothelial cells, and the haemolytic effects occurred at concentrations 10- to 100-fold higher than those required for bacterial cell lysis. For insight into the mechanism of action of SC4 peptide-amphiphiles, CD, NMR and fluorescence spectroscopy studies were performed in micelle and liposome models of eukaryotic and bacterial cell membranes. CD indicated that SC4 peptide-amphiphiles had the strongest helical tendencies in liposomes mimicking bacterial membranes, and strong membrane integration of the SC4 peptide-amphiphiles was observed using tryptophan fluorescence spectroscopy under these conditions; results that correlated with the increased bactericidal activities of SC4 peptide-amphiphiles. NMR structural analysis in micelles demonstrated that the two-thirds of the peptide closest to the fatty acid tail exhibited a helical conformation, with the positively-charged side of the amphipathic helix interacting more with the model membrane surface. These results indicate that conjugation of a fatty acid chain to the SC4 peptide enhances membrane interactions, stabilizes helical structure in the membrane-bound state and increases bactericidal potency. PMID:14609430

  7. Relative Roles of the Cellular and Humoral Responses in the Drosophila Host Defense against Three Gram-Positive Bacterial Infections

    PubMed Central

    Cho, Ju Hyun; Lee, Janice; Lafarge, Marie-Céline; Kocks, Christine; Ferrandon, Dominique

    2011-01-01

    Background Two NF-kappaB signaling pathways, Toll and immune deficiency (imd), are required for survival to bacterial infections in Drosophila. In response to septic injury, these pathways mediate rapid transcriptional activation of distinct sets of effector molecules, including antimicrobial peptides, which are important components of a humoral defense response. However, it is less clear to what extent macrophage-like hemocytes contribute to host defense. Methodology/Principal Findings In order to dissect the relative importance of humoral and cellular defenses after septic injury with three different Gram-positive bacteria (Micrococcus luteus, Enterococcus faecalis, Staphylococcus aureus), we used latex bead pre-injection to ablate macrophage function in flies wildtype or mutant for various Toll and imd pathway components. We found that in all three infection models a compromised phagocytic system impaired fly survival – independently of concomitant Toll or imd pathway activation. Our data failed to confirm a role of the PGRP-SA and GNBP1 Pattern Recognition Receptors for phagocytosis of S. aureus. The Drosophila scavenger receptor Eater mediates the phagocytosis by hemocytes or S2 cells of E. faecalis and S. aureus, but not of M. luteus. In the case of M. luteus and E. faecalis, but not S. aureus, decreased survival due to defective phagocytosis could be compensated for by genetically enhancing the humoral immune response. Conclusions/Significance Our results underscore the fundamental importance of both cellular and humoral mechanisms in Drosophila immunity and shed light on the balance between these two arms of host defense depending on the invading pathogen. PMID:21390224

  8. B. subtilis GS67 protects C. elegans from Gram-positive pathogens via fengycin-mediated microbial antagonism.

    PubMed

    Iatsenko, Igor; Yim, Joshua J; Schroeder, Frank C; Sommer, Ralf J

    2014-11-17

    Studies on Caenorhabditis elegans have provided detailed insight into host-pathogen interactions. Usually, the E. coli strain OP50 is used as food source for laboratory studies, but recent work has shown that a variety of bacteria have dramatic effects on C. elegans physiology, including immune responses. However, the mechanisms by which different bacteria impact worm resistance to pathogens are poorly understood. Although pathogen-specific immune priming is often discussed as a mechanism underlying such observations, interspecies microbial antagonism might represent an alternative mode of action. Here, we use several natural Bacillus strains to study their effects on nematode survival upon pathogen challenge. We show that B. subtilis GS67 persists in the C. elegans intestine and increases worm resistance to Gram-positive pathogens, suggesting that direct inhibition of pathogens might be the primary protective mechanism. Indeed, chemical and genetic analyses identified the lipopeptide fengycin as the major inhibitory molecule produced by B. subtilis GS67. Specifically, a fengycin-defective mutant of B. subtilis GS67 lost inhibitory activity against pathogens and was unable to protect C. elegans from infections. Furthermore, we found that purified fengycin cures infected worms in a dose-dependent manner, indicating that it acts as an antibiotic. Our results reveal a molecular mechanism for commensal-mediated C. elegans protection and highlight the importance of interspecies microbial antagonism for the outcome of animal-pathogen interactions. Furthermore, our work strengthens C. elegans as an in vivo model to reveal protective mechanisms of commensal bacteria, including those relevant to mammalian hosts. PMID:25448001

  9. Unexpected Roles for Toll-Like Receptor 4 and TRIF in Intraocular Infection with Gram-Positive Bacteria

    PubMed Central

    Parkunan, Salai Madhumathi; Randall, C. Blake; Coburn, Phillip S.; Astley, Roger A.; Staats, Rachel L.

    2015-01-01

    Inflammation caused by infection with Gram-positive bacteria is typically initiated by interactions with Toll-like receptor 2 (TLR2). Endophthalmitis, an infection and inflammation of the posterior segment of the eye, can lead to vision loss when initiated by a virulent microbial pathogen. Endophthalmitis caused by Bacillus cereus develops as acute inflammation with infiltrating neutrophils, and vision loss is potentially catastrophic. Residual inflammation observed during B. cereus endophthalmitis in TLR2−/− mice led us to investigate additional innate pathways that may trigger intraocular inflammation. We first hypothesized that intraocular inflammation during B. cereus endophthalmitis would be controlled by MyD88- and TRIF-mediated signaling, since MyD88 and TRIF are the major adaptor molecules for all bacterial TLRs. In MyD88−/− and TRIF−/− mice, we observed significantly less intraocular inflammation than in eyes from infected C57BL/6J mice, suggesting an important role for these TLR adaptors in B. cereus endophthalmitis. These results led to a second hypothesis, that TLR4, the only TLR that signals through both MyD88 and TRIF signaling pathways, contributed to inflammation during B. cereus endophthalmitis. Surprisingly, B. cereus-infected TLR4−/− eyes also had significantly less intraocular inflammation than infected C57BL/6J eyes, indicating an important role for TLR4 in B. cereus endophthalmitis. Taken together, our results suggest that TLR4, TRIF, and MyD88 are important components of the intraocular inflammatory response observed in experimental B. cereus endophthalmitis, identifying a novel innate immune interaction for B. cereus and for this disease. PMID:26195555

  10. Flow cytometric evaluation of physico-chemical impact on Gram-positive and Gram-negative bacteria

    PubMed Central

    Fröhling, Antje; Schlüter, Oliver

    2015-01-01

    Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfill the requirements of food safety without affecting the produce quality. The efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the time span needed to obtain results. The aim of this study was to compare the inactivation effects of peracetic acid (PAA), ozonated water (O3), and cold atmospheric pressure plasma (CAPP) on Gram-positive and Gram-negative bacteria using flow cytometric methods. E. coli cells were completely depolarized after treatment (15 s) with 0.25% PAA at 10°C, and after treatment (10 s) with 3.8 mg l−1 O3 at 12°C. The membrane potential of CAPP treated cells remained almost constant at an operating power of 20 W over a time period of 3 min, and subsequently decreased within 30 s of further treatment. Complete membrane permeabilization was observed after 10 s O3 treatment, but treatment with PAA and CAPP did not completely permeabilize the cells within 2 and 4 min, respectively. Similar results were obtained for esterase activity. O3 inactivates cellular esterase but esterase activity was detected after 4 min CAPP treatment and 2 min PAA treatment. L. innocua cells and P. carotovorum cells were also permeabilized instantaneously by O3 treatment at concentrations of 3.8 ± 1 mg l−1. However, higher membrane permeabilization of L. innocua and P. carotovorum than of E. coli was observed at CAPP treatment of 20 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. Important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process parameters. PMID

  11. Target affinities of faropenem to and its impact on the morphology of gram-positive and gram-negative bacteria.

    PubMed

    Dalhoff, A; Nasu, T; Okamoto, K

    2003-07-01

    Faropenem is a new oral beta-lactam antibiotic unique from carbapenems and other available beta-lactams. Determinants of the in vitro activity of beta-lactam antibiotics include affinity to penicillin-binding proteins (PBPs) and beta-lactamase stability. In this study, the binding affinity of faropenem to various PBPs and its impact on the morphology of Staphylococcus aureus and Escherichia coli were evaluated. In general, faropenem demonstrated high binding affinity to high-molecular-weight PBPs but low affinity to low-molecular-weight PBPs. In S. aureus and Streptococcus pneumoniae, faropenem exhibited high binding affinity to PBP1, followed by PBP3 and PBP2. In E. coli, faropenem showed the highest affinity for PBP2, followed by PBP1A, PBP1B, PBP3 and PBP4. In Proteus vulgaris, binding was highest to PBP4, followed by PBP1A, PBP2 and PBP3. In Serratia marcescens, faropenem bound preferentially to PBP2 and PBP4. Exposure of S. aureus to faropenem at minimum inhibitory concentrations (MICs) of 1/8 or 1/4 resulted in irregular septum formation. At 1x MIC or higher, a larger number of lysed cells were observed. Exposure of E. coli to 1/8x MIC or 1/4x MIC also induced changes in cellular shape; the normal rod-shaped form changed to a spherical form in a time-dependent manner. After exposure of E. coli to 1x MIC for 2 h, bulging-shaped E. coli cells were observed and after 4 h of exposure cell lysis was demonstrated. In the presence of 4x MIC, spheroplast-like forms and cell lysis were observed. The morphological changes triggered by faropenem are in agreement with the PBP binding affinities reported. Thus, the high binding affinities of faropenem to PBPs from gram-negative and gram-positive bacteria are mirrored by its pronounced and concentration-dependent bactericidal effect. PMID:12886052

  12. Distinctive Binding of Avibactam to Penicillin-Binding Proteins of Gram-Negative and Gram-Positive Bacteria

    PubMed Central

    Asli, Abdelhamid; Brouillette, Eric; Krause, Kevin M.; Nichols, Wright W.

    2015-01-01

    Avibactam is a novel non-β-lactam β-lactamase inhibitor that covalently acylates a variety of β-lactamases, causing inhibition. Although avibactam presents limited antibacterial activity, its acylation ability toward bacterial penicillin-binding proteins (PBPs) was investigated. Staphylococcus aureus was of particular interest due to the reported β-lactamase activity of PBP4. The binding of avibactam to PBPs was measured by adding increasing concentrations to membrane preparations of a variety of Gram-positive and Gram-negative bacteria prior to addition of the fluorescent reagent Bocillin FL. Relative binding (measured here as the 50% inhibitory concentration [IC50]) to PBPs was estimated by quantification of fluorescence after gel electrophoresis. Avibactam was found to selectively bind to some PBPs. In Escherichia coli, Pseudomonas aeruginosa, Haemophilus influenzae, and S. aureus, avibactam primarily bound to PBP2, with IC50s of 0.92, 1.1, 3.0, and 51 μg/ml, respectively, whereas binding to PBP3 was observed in Streptococcus pneumoniae (IC50, 8.1 μg/ml). Interestingly, avibactam was able to significantly enhance labeling of S. aureus PBP4 by Bocillin FL. In PBP competition assays with S. aureus, where avibactam was used at a fixed concentration in combination with varied amounts of ceftazidime, the apparent IC50 of ceftazidime was found to be very similar to that determined for ceftazidime when used alone. In conclusion, avibactam is able to covalently bind to some bacterial PBPs. Identification of those PBP targets may allow the development of new diazabicyclooctane derivatives with improved affinity for PBPs or new combination therapies that act on multiple PBP targets. PMID:26574008

  13. Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

    2014-07-01

    Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results

  14. Antibacterial Activity of Sphingoid Bases and Fatty Acids against Gram-Positive and Gram-Negative Bacteria

    PubMed Central

    Fischer, Carol L.; Drake, David R.; Dawson, Deborah V.; Blanchette, Derek R.; Brogden, Kim A.

    2012-01-01

    There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity—the sphingoid bases d-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid—against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P < 0.0001) for each bacterial species except Serratia marcescens and Pseudomonas aeruginosa. d-Sphingosine (MBC range, 0.3 to 19.6 μg/ml), dihydrosphingosine (MBC range, 0.6 to 39.1 μg/ml), and phytosphingosine (MBC range, 3.3 to 62.5 μg/ml) were active against all bacteria except S. marcescens and P. aeruginosa (MBC > 500 μg/ml). Sapienic acid (MBC range, 31.3 to 375.0 μg/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 μg/ml). Lauric acid (MBC range, 6.8 to 375.0 μg/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 μg/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection. PMID:22155833

  15. Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria

    PubMed Central

    2014-01-01

    Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results

  16. Genome sequence of Desulfitobacterium hafniense DCB-2, a Gram-positive anaerobe capable of dehalogenation and metal reduction

    PubMed Central

    2012-01-01

    Background The genome of the Gram-positive, metal-reducing, dehalorespiring Desulfitobacterium hafniense DCB-2 was sequenced in order to gain insights into its metabolic capacities, adaptive physiology, and regulatory machineries, and to compare with that of Desulfitobacterium hafniense Y51, the phylogenetically closest strain among the species with a sequenced genome. Results The genome of Desulfitobacterium hafniense DCB-2 is composed of a 5,279,134-bp circular chromosome with 5,042 predicted genes. Genome content and parallel physiological studies support the cell's ability to fix N2 and CO2, form spores and biofilms, reduce metals, and use a variety of electron acceptors in respiration, including halogenated organic compounds. The genome contained seven reductive dehalogenase genes and four nitrogenase gene homologs but lacked the Nar respiratory nitrate reductase system. The D. hafniense DCB-2 genome contained genes for 43 RNA polymerase sigma factors including 27 sigma-24 subunits, 59 two-component signal transduction systems, and about 730 transporter proteins. In addition, it contained genes for 53 molybdopterin-binding oxidoreductases, 19 flavoprotein paralogs of the fumarate reductase, and many other FAD/FMN-binding oxidoreductases, proving the cell's versatility in both adaptive and reductive capacities. Together with the ability to form spores, the presence of the CO2-fixing Wood-Ljungdahl pathway and the genes associated with oxygen tolerance add flexibility to the cell's options for survival under stress. Conclusions D. hafniense DCB-2's genome contains genes consistent with its abilities for dehalogenation, metal reduction, N2 and CO2 fixation, anaerobic respiration, oxygen tolerance, spore formation, and biofilm formation which make this organism a potential candidate for bioremediation at contaminated sites. PMID:22316246

  17. Cellular fatty acid composition as an adjunct to the identification of asporogenous, aerobic gram-positive rods.

    PubMed

    Bernard, K A; Bellefeuille, M; Ewan, E P

    1991-01-01

    Cellular fatty acid (CFA) compositions of 561 asporogenous, aerobic gram-positive rods were analyzed by gas-liquid chromatography as an adjunct to their identification when grown on blood agar at 35 degrees C. The organisms could be divided into two groups. In the first group (branched-chain type), which included coryneform CDC groups A-3, A-4, and A-5; some strains of B-1 and B-3; "Corynebacterium aquaticum"; Brevibacterium liquefaciens; Rothia dentocariosa; and Listeria spp., the rods had sizable quantities of antiesopentadecanoic (Ca15:0) and anteisoheptadecanoic (Ca17:0) acids. Other species with these types of CFA included B. acetylicum, which contained large amounts of isotridecanoic (Ci13:0) and anteisotridecanoic (Ca13:0) acids. CFAs useful for distinguishing among Jonesia denitrificans, Oerskovia spp., some strains of CDC groups B-1 and B-3, Kurthia spp., and Propionibacterium avidum were hexadecanoic (C 16:0) acid, isopentadecanoic (Ci15:0) acid, and Ca15:0). The second group (straight-chained type), which included Actinomyces pyogenes; Arcanobacterium haemolyticum; C. bovis; C. cystitidis; C. diphtheriae; C. flavescens, "C. gentalium"; C. jeikeium; C. kutscheri; C. matruchotii; C .minutissimum; C. mycetoides; C. pilosum; C. pseudodiphtheriticum; "C. pseudogenitalium"; C. pseudotuberculosis; C. renale; CDC groups 1, 2, ANF-1, D-2, E, F-1, F-2, G-1, G-2, and I-2; C. striatum; "C. tuberculostearicum"; C. ulcerans; C. vitarumen; C. xerosis; and Erysipelothrix rhusiopathiae, was typified by significant quantities of hexadecanoic (C16:0) and oleic acids (C18:cis9), with differences in the amounts of linoleic acid (C18:2), stearic acid (C18:0), an unnamed peak (equivalent chain length, 14.966), and small quantities of other known saturated and unsaturated fatty acids. CFA composition of these organisms was sufficiently discriminatory to assist in classification but could not be used as the sole means of identification. PMID:1899679

  18. Distinctive Binding of Avibactam to Penicillin-Binding Proteins of Gram-Negative and Gram-Positive Bacteria.

    PubMed

    Asli, Abdelhamid; Brouillette, Eric; Krause, Kevin M; Nichols, Wright W; Malouin, François

    2016-02-01

    Avibactam is a novel non-β-lactam β-lactamase inhibitor that covalently acylates a variety of β-lactamases, causing inhibition. Although avibactam presents limited antibacterial activity, its acylation ability toward bacterial penicillin-binding proteins (PBPs) was investigated. Staphylococcus aureus was of particular interest due to the reported β-lactamase activity of PBP4. The binding of avibactam to PBPs was measured by adding increasing concentrations to membrane preparations of a variety of Gram-positive and Gram-negative bacteria prior to addition of the fluorescent reagent Bocillin FL. Relative binding (measured here as the 50% inhibitory concentration [IC50]) to PBPs was estimated by quantification of fluorescence after gel electrophoresis. Avibactam was found to selectively bind to some PBPs. In Escherichia coli, Pseudomonas aeruginosa, Haemophilus influenzae, and S. aureus, avibactam primarily bound to PBP2, with IC50s of 0.92, 1.1, 3.0, and 51 μg/ml, respectively, whereas binding to PBP3 was observed in Streptococcus pneumoniae (IC50, 8.1 μg/ml). Interestingly, avibactam was able to significantly enhance labeling of S. aureus PBP4 by Bocillin FL. In PBP competition assays with S. aureus, where avibactam was used at a fixed concentration in combination with varied amounts of ceftazidime, the apparent IC50 of ceftazidime was found to be very similar to that determined for ceftazidime when used alone. In conclusion, avibactam is able to covalently bind to some bacterial PBPs. Identification of those PBP targets may allow the development of new diazabicyclooctane derivatives with improved affinity for PBPs or new combination therapies that act on multiple PBP targets. PMID:26574008

  19. Unravelling a vicious circle: animal feed marketed in Costa Rica contains irregular concentrations of tetracyclines and abundant oxytetracycline-resistant Gram-positive bacteria.

    PubMed

    Granados-Chinchilla, Fabio; Alfaro, Margarita; Chavarría, Guadalupe; Rodríguez, César

    2014-01-01

    Diverse tetracyclines are used to prevent and control bacterial infections in livestock and farmed fish. These drugs are administered through the diet, but farmers seldom check whether feed contains antibiotic-resistant bacteria that may colonise their crops or transfer their resistance traits to species of veterinary relevance. To examine whether antibiotic dosage defines the abundance of antibiotic-resistant bacteria in animal feed, we determined the concentration of parental compounds and epimers of oxytetracycline (OTC), doxycycline, tetracycline and chlortetracycline, as well as the abundance and resistance level of OTC-resistant bacteria in samples of fish (n = 21), poultry (n = 21), swine (n = 21), and shrimp feed (n = 21) marketed in Costa Rica. Fish feed contained the highest amounts of tetracyclines (119-8365 mg kg(-1)) and the largest proportion of bacteria resistant to 10 μg ml(-1) (1.8-92.4%) or 100 μg ml(-1) of OTC (12.5-63.8%). Poultry (78-438 mg kg(-1)) and swine (41-1076 mg kg(-1)) feed had intermediate concentrations of tetracyclines and OTC-resistant bacteria (0.2-66% and 0.3-49%, respectively), whereas shrimp feed showed the lowest amounts of tetracyclines (21.5-50.3 mg kg(-1)), no OTC and no culturable OTC-resistant bacteria. In line with these results, the MIC50 of OTC for 150 isolates from fish and poultry feed was > 256 µg ml(-1), while that of 150 bacteria isolated from swine feed was 192 µg ml(-1). Phenotypic tests, fatty acid profiles and proteotypic analyses by matrix-assisted laser desorption/ionisation-time of flight mass-spectroscopy revealed that most OTC-resistant isolates were Gram-positive bacteria of low G+C% content from the genera Staphylococcus and Bacillus. Clear correlations between OTC dosage and feed colonisation with OTC-resistant bacteria were seen in medicated feed for fish (r = 0.179-0.651). Nonetheless, some unmedicated feed for fish, swine and poultry contained large populations of OTC-resistant bacteria

  20. A Pathway Closely Related to the d-Tagatose Pathway of Gram-Negative Enterobacteria Identified in the Gram-Positive Bacterium Bacillus licheniformis

    PubMed Central

    Van der Heiden, Edwige; Lebrun, Sarah; Freichels, Régine; Brans, Alain; Vastenavond, Christian M.; Galleni, Moreno; Joris, Bernard

    2013-01-01

    We report the first identification of a gene cluster involved in d-tagatose catabolism in Bacillus licheniformis. The pathway is closely related to the d-tagatose pathway of the Gram-negative bacterium Klebsiella oxytoca, in contrast to the d-tagatose 6-phosphate pathway described in the Gram-positive bacterium Staphylococcus aureus. PMID:23524682

  1. Antimicrobial susceptibility of clinical isolates from earthquake victims in Wenchuan.

    PubMed

    Kang, M; Xie, Y; Mintao, C; Chen, Z; Chen, H; Fan, H; Chen, W; Guo, X

    2009-01-01

    On 12 May 2008, an earthquake measuring 8.0 on the Richter scale struck Wenchuan County, Sichuan, China. Between 12 May and 11 June, 1823 victims were hospitalized in West China Hospital. These patients were severely injured, and most of their wounds were contaminated. Here, the results of bacteriological identification and antibiotic susceptibility testing of 725 non-duplicate isolates from earthquake victims are presented. Gram-negative bacilli were most frequently isolated (71.3%). Only 18.9% of isolates were Gram-positive bacteria; Candida spp. accounted for 9.7%, and Gram-negative cocci for 0.1%. After anaerobic culture, four Clostridium sordellii strains and one Clostridium bifermentans strain were isolated from deep wounds. Specimen culture from earthquake victims revealed a spectrum of pathogens and antibiotic susceptibilities that was different from that usually encountered in West China Hospital, especially concerning methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase producers, and multidrug-resistant (MDR) non-fermenting Gram-negative bacilli. The pathophysiology of the injuries in earthquake victims was different from that in the patients who were not earthquake victims. A combination of environmental bacteria with a high proportion of Gram-negative bacteria was often observed in the earthquake victims. Approximately 26% of all earthquake victims were shown to be carriers of MDR microorganisms. Therefore, appropriate microbiological assessment upon admission, and identification of patients to be put in quarantine, is of paramount importance. PMID:19220339

  2. Characterization of ear fluid isolates of Alloiococcus otitidis from patients with recurrent otitis media.

    PubMed Central

    Bosley, G S; Whitney, A M; Pruckler, J M; Moss, C W; Daneshvar, M; Sih, T; Talkington, D F

    1995-01-01

    Nineteen isolates of Alloiococcus otitidis from ear fluid samples collected by tympanostomy from patients at four geographic locations were identified by phenotypic characterization and genetic relatedness. Initial growth of A. otitidis isolates occurred after 3 days at 37 degrees C on brain heart infusion (BHI) agar with 5% rabbit blood. Heavy growth occurred in BHI broth supplemented with 0.07% lecithin and 0.5% Tween 80 after 4 days of incubation. The isolates were gram-positive cocci that divided on an irregular plane and produced metabolic lactic acid, pyrrolidonyl arylamidase, and leucine aminopeptidase. These cocci grew sparsely in 6.5% NaCl-BHI broth, were asaccharolytic on both fermentative and oxidative bases, and were cytochrome negative by the iron-porphyrin test. The cellular fatty acid profile of A. otitidis was distinguished from those of related genera and characterized by major amounts ( > or = 14%) of 16:0, 18:2, 18:1 omega 9c, and 18:0 and smaller amounts of 14:0, 16:1 omega 7c, 17:0, and 18:1 omega 7c. Fifteen isolates demonstrated > 69% relatedness by DNA-DNA hybridization. Four isolates plus the original 15 were confirmed as A. otitidis by dot blot hybridization with a digoxigenin-labeled nucleotide probe specific for this species. The intergenic space between the genes coding for the 16S and 23S rRNAs of alloiococci was amplified by PCR, analyzed by restriction fragment length polymorphism, and determined to consist of three different genetic types. Although beta-lactamase negative, A. otitidis demonstrated intermediate levels of resistance to beta-lactams, including expanded-spectrum cephalosporins, and were resistant to trimethoprim-sulfamethoxazole and erythromycin. PMID:8576338

  3. Overcoming function annotation errors in the Gram-positive pathogen Streptococcus suis by a proteomics-driven approach

    PubMed Central

    Rodríguez-Ortega, Manuel J; Luque, Inmaculada; Tarradas, Carmen; Bárcena, José A

    2008-01-01

    Background Annotation of protein-coding genes is a key step in sequencing projects. Protein functions are mainly assigned on the basis of the amino acid sequence alone by searching of homologous proteins. However, fully automated annotation processes often lead to wrong prediction of protein functions, and therefore time-intensive manual curation is often essential. Here we describe a fast and reliable way to correct function annotation in sequencing projects, focusing on surface proteomes. We use a proteomics approach, previously proven to be very powerful for identifying new vaccine candidates against Gram-positive pathogens. It consists of shaving the surface of intact cells with two proteases, the specific cleavage-site trypsin and the unspecific proteinase K, followed by LC/MS/MS analysis of the resulting peptides. The identified proteins are contrasted by computational analysis and their sequences are inspected to correct possible errors in function prediction. Results When applied to the zoonotic pathogen Streptococcus suis, of which two strains have been recently sequenced and annotated, we identified a set of surface proteins without cytoplasmic contamination: all the proteins identified had exporting or retention signals towards the outside and/or the cell surface, and viability of protease-treated cells was not affected. The combination of both experimental evidences and computational methods allowed us to determine that two of these proteins are putative extracellular new adhesins that had been previously attributed a wrong cytoplasmic function. One of them is a putative component of the pilus of this bacterium. Conclusion We illustrate the complementary nature of laboratory-based and computational methods to examine in concert the localization of a set of proteins in the cell, and demonstrate the utility of this proteomics-based strategy to experimentally correct function annotation errors in sequencing projects. This approach also contributes to

  4. Conjunctival sac bacterial flora isolated prior to cataract surgery

    PubMed Central

    Suto, Chikako; Morinaga, Masahiro; Yagi, Tomoko; Tsuji, Chieko; Toshida, Hiroshi

    2012-01-01

    Objective To determine the trends of conjunctival sac bacterial flora isolated from patients prior to cataract surgery. Subjects and methods The study comprised 579 patients (579 eyes) who underwent cataract surgery. Specimens were collected by lightly rubbing the inferior palpebral conjunctival sac with a sterile cotton swab 2 weeks before surgery, and then cultured for isolation of bacteria and antimicrobial sensitivity testing. The bacterial isolates and percentage of drug-resistant isolates were compared among age groups and according to whether or not patients had diabetes mellitus, hyperlipidemia, dialysis therapy, oral steroid use, dry eye syndrome, or allergic conjunctivitis. Results The bacterial isolation rate was 39.2%. There were 191 strains of Gram-positive cocci, accounting for the majority of all isolates (67.0%), among which methicillin-sensitive coagulase-negative staphylococci was the most frequent (127 strains, 44.5%), followed by methicillin-resistant coagulase-negative staphylococci (37 strains, 12.7%). All 76 Gram-positive bacillary isolates (26.7%) were from the genus Corynebacterium. Among the 16 Gram-negative bacillary isolates (5.9%), the most frequent was Escherichia coli (1.0%). The bacterial isolation rate was higher in patients >60 years old, and was lower in patients with dry eye syndrome, patients under topical treatment for other ocular disorders, and patients with hyperlipidemia. There was no significant difference in bacterial isolation rate with respect to the presence/absence of diabetes mellitus, steroid therapy, dialysis, or a history of allergic conjunctivitis. Methicillin-resistant coagulase-negative staphylococci showed a significantly higher detection rate in diabetic patients than nondiabetic patients (20.3% versus 7.0%, P < 0.05). The percentage of all isolates resistant to levofloxacin, cefmenoxime, and tobramycin was 14.0%, 15.2%, and 17.9%, respectively, with no significant differences among these drugs. Conclusion

  5. Role for intracellular platelet-activating factor in the circulatory failure in a model of gram-positive shock.

    PubMed Central

    De Kimpe, S. J.; Thiemermann, C.; Vane, J. R.

    1995-01-01

    ) was inhibited by 74 +/- 4% by WEB2086 (3 x 10(-4) M), but not by BN52021, indicating that only WEB2086 acts on intracellular PAF receptors. 6. Thus, the intracellular release of PAF contributes to the circulatory and renal failure and induction of nitric oxide synthase elicited by LTA in anaesthetized rats. The difference between the two structurally different PAF antagonists in our septic shock models using either LTA or lipopolysaccharide (LPS), shows the importance of models for Gram-positive sepsis in the elucidation of the pathophysiology of septic shock and for the evaluation of potential drugs. PMID:8719795

  6. Role for intracellular platelet-activating factor in the circulatory failure in a model of gram-positive shock.

    PubMed

    De Kimpe, S J; Thiemermann, C; Vane, J R

    1995-12-01

    ) was inhibited by 74 +/- 4% by WEB2086 (3 x 10(-4) M), but not by BN52021, indicating that only WEB2086 acts on intracellular PAF receptors. 6. Thus, the intracellular release of PAF contributes to the circulatory and renal failure and induction of nitric oxide synthase elicited by LTA in anaesthetized rats. The difference between the two structurally different PAF antagonists in our septic shock models using either LTA or lipopolysaccharide (LPS), shows the importance of models for Gram-positive sepsis in the elucidation of the pathophysiology of septic shock and for the evaluation of potential drugs. PMID:8719795

  7. Collagen-binding Microbial Surface Components Recognizing Adhesive Matrix Molecule (MSCRAMM) of Gram-positive Bacteria Inhibit Complement Activation via the Classical Pathway*

    PubMed Central

    Kang, Mingsong; Ko, Ya-Ping; Liang, Xiaowen; Ross, Caná L.; Liu, Qing; Murray, Barbara E.; Höök, Magnus

    2013-01-01

    Members of a family of collagen-binding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) from Gram-positive bacteria are established virulence factors in several infectious diseases models. Here, we report that these adhesins also can bind C1q and act as inhibitors of the classical complement pathway. Molecular analyses of Cna from Staphylococcus aureus suggested that this prototype MSCRAMM bound to the collagenous domain of C1q and interfered with the interactions of C1r with C1q. As a result, C1r2C1s2 was displaced from C1q, and the C1 complex was deactivated. This novel function of the Cna-like MSCRAMMs represents a potential immune evasion strategy that could be used by numerous Gram-positive pathogens. PMID:23720782

  8. Multidrug-Resistance and Toxic Metal Tolerance of Medically Important Bacteria Isolated from an Aquaculture System

    PubMed Central

    Resende, Juliana Alves; Silva, Vânia L.; Fontes, Cláudia Oliveira; Souza-Filho, Job Alves; de Oliveira, Tamara Lopes Rocha; Coelho, Cíntia Marques; César, Dionéia Evangelista; Diniz, Cláudio Galuppo

    2012-01-01

    The use of antimicrobials and toxic metals should be considered carefully in aquaculture and surrounding environments. We aimed to evaluate medically relevant bacteria in an aquaculture system and their susceptibility to antimicrobials and toxic metals. Selective cultures for enterobacteria (ENT), non-fermenting Gram-negative rods (NFR) and Gram-positive cocci (GPC) were obtained from water samples collected in two different year seasons. The isolated bacteria were biochemically identified and antimicrobial and toxic metal susceptibility patterns were determined. Overall, 407 representative strains were recovered. In general, bacteria isolated from fish ponds showed higher multiple antibiotic resistance indices when compared to those isolated from a water-fed canal. Resistance to penicillin and azithromycin was observed more frequently in the GPC group, whereas resistance to ampicillin and ampicillin/sulbactam or gentamicin was observed more frequently in the ENT and NFR groups, respectively. All the isolated bacteria were tolerant to nickel, zinc, chromium and copper at high levels (≥1,024 μg mL−1), whereas tolerance to cadmium and mercury varied among the isolated bacteria (2–1,024 μg mL−1). Multidrug-resistant bacteria were more frequent and diverse in fish ponds than in the water-fed canal. A positive correlation was observed between antimicrobial resistance and metal tolerance. The data point out the need for water treatment associated with the aquaculture system. PMID:22972388

  9. [A new method for the disruption of cell walls of gram-positive bacteria and mycobacteria on the point of nucleic acid extraction: sand method].

    PubMed

    Şahin, Fikret; Kıyan, Mehmet; Karasartova, Djursun; Çalgın, M Kerem; Akhter, Shameem; Türegün Atasoy, Buse

    2016-01-01

    Nowadays molecular methods are widely used in the rapid diagnosis of infectious agents. Polymerase chain reaction (PCR) is the most preferred method for this purpose. Obtaining sufficient and pure DNA or RNA is important for the PCR. Different DNA extraction protocols such as phenol-chloroform, proteinase K, glass beads and boiling have been used successfully for DNA isolation from gram-negative bacteria. However since gram-positive bacteria have a thicker layer of peptidoglycan and mycobacteria have complex glycolipids in their cell walls, for the isolation of DNA or RNA from these microorganisms, the complex cell wall structure must be eliminated. For this purpose, the bacterial cell wall must be completely or partially removed forming sferoblast using lysostaphin in the Staphylococcus genus as gram-positive bacteria and using a chemical like cetyltrimethyl ammonium bromide for the Mycobacterium genus. In this study, we planned to use sand particles for the mechanical elimination of the cell wall without any need for chemicals and we called this procedure as "sand method". For the purpose of DNA extraction, the fine-grained sand was washed with ddH(2)O without losing small particles and then sterilized by autoclaving. For the purpose of RNA extraction; the sand was washed with ddH(2)O, incubated for 30 minutes with 10% HCl, and then autoclaved. A methicillin-resistant Staphylococcus aureus (MRSA) strain previously isolated and identified from a clinical specimen was mixed in 100 µl Tris-EDTA buffer with 100 mg sand. The mixture of bacteria and sand was vortexed at the maximum speed for 5 minutes. The MRSA-sand mix was treated with proteinase K and phenol-chloroform, and ethanol precipitation protocol was then followed for obtaining DNA. For comparison of the sand method with the other methods, the same amount of bacteria used in the sand method was incubated for one hour with lysostaphin, and then the proteinase K DNA extraction method were completed in the same

  10. Effectiveness of sequential intravenous-to-oral antibiotic switch therapy in hospitalized patients with gram-positive infection: the SEQUENCE cohort study.

    PubMed

    Rodriguez-Pardo, D; Pigrau, C; Campany, D; Diaz-Brito, V; Morata, L; de Diego, I C; Sorlí, L; Iftimie, S; Pérez-Vidal, R; García-Pardo, G; Larrainzar-Coghen, T; Almirante, B

    2016-08-01

    Switching from intravenous to oral antibiotic therapy may improve inpatient management and reduce hospital stays and the complications of intravenous treatment. We aimed to assess the effectiveness of intravenous-to-oral antibiotic switch therapy and an early discharge algorithm in hospitalized patients with gram-positive infection. We performed a prospective cohort study with a retrospective comparison cohort, recruited from eight tertiary, acute-care Spanish referral hospitals. All patients included had culture-confirmed methicillin-resistant gram-positive infection, or methicillin-susceptible gram-positive infection and beta-lactam allergy and had received intravenous treatment with glycopeptides, lipopeptides, or linezolid. The study comprised two cohorts: the prospective cohort to assess the effectiveness of a sequential intravenous-to-oral antibiotic switch algorithm and early discharge, and a retrospective cohort in which the algorithm had not been applied, used as the comparator. A total of 247 evaluable patients were included; 115 in the prospective and 132 in the retrospective cohort. Forty-five retrospective patients (34 %) were not changed to oral antibiotics, and 87 (66 %) were changed to oral antibiotics without following the proposed algorithm. The duration of hospitalization was significantly shorter in the prospective cohort compared to the retrospective group that did not switch to oral drugs (16.7 ± 18.7 vs 23 ± 13.4 days, P  < 0.001). No differences were observed regarding the incidence of catheter-related bacteraemia (4.4 % vs 2.6 %, P = 0.621). Our results suggest that an intravenous-to-oral antibiotic switch strategy is effective for reducing the length of hospital stay in selected hospitalized patients with gram-positive infection. PMID:27180242

  11. Targeting of key pathogenic factors from gram-positive bacteria by the soluble ectodomain of the scavenger-like lymphocyte receptor CD6.

    PubMed

    Martínez-Florensa, Mario; Consuegra-Fernández, Marta; Martínez, Vanesa G; Cañadas, Olga; Armiger-Borràs, Noelia; Bonet-Roselló, Lizette; Farrán, Aina; Vila, Jordi; Casals, Cristina; Lozano, Francisco

    2014-04-01

    Gram-positive bacteria cause a broad spectrum of infection-related diseases in both immunocompetent and immunocompromised hosts, ranging from localized infections to severe systemic conditions such as septic and toxic shock syndromes. This situation has been aggravated by the recent emergence of multidrug-resistant strains, thus stressing the need for alternative therapeutic approaches. One such possibility would be modulating the host's immune response. Herein, the potential use of a soluble form of the scavenger-like human lymphocyte receptor CD6 (shCD6) belonging to an ancient family of innate immune receptors has been evaluated. shCD6 can bind to a broad spectrum of gram-positive bacteria thanks to the recognition of highly conserved cell wall components (lipoteichoic acid [LTA] and peptidoglycan [PGN]), which are essential for their viability and pathogenicity and are not amenable to antibiotic resistance. shCD6 has in vitro inhibitory effects on both bacterial growth and Toll-like receptor-mediated inflammatory response induced by LTA plus PGN. In vivo infusion of shCD6 improves survival on mouse models of septic shock by Staphylococcus aureus (either multidrug-resistant or -sensitive) or their endotoxins (LTA + PGN) or exotoxins (TSST-1). These results support the use of shCD6 and/or other scavenger-like immune receptors in the treatment of severe gram-positive-induced infectious conditions. PMID:24265437

  12. Resilience in the Face of Uncertainty: Sigma Factor B Fine-Tunes Gene Expression To Support Homeostasis in Gram-Positive Bacteria.

    PubMed

    Guldimann, Claudia; Boor, Kathryn J; Wiedmann, Martin; Guariglia-Oropeza, Veronica

    2016-08-01

    Gram-positive bacteria are ubiquitous and diverse microorganisms that can survive and sometimes even thrive in continuously changing environments. The key to such resilience is the ability of members of a population to respond and adjust to dynamic conditions in the environment. In bacteria, such responses and adjustments are mediated, at least in part, through appropriate changes in the bacterial transcriptome in response to the conditions encountered. Resilience is important for bacterial survival in diverse, complex, and rapidly changing environments and requires coordinated networks that integrate individual, mechanistic responses to environmental cues to enable overall metabolic homeostasis. In many Gram-positive bacteria, a key transcriptional regulator of the response to changing environmental conditions is the alternative sigma factor σ(B) σ(B) has been characterized in a subset of Gram-positive bacteria, including the genera Bacillus, Listeria, and Staphylococcus Recent insight from next-generation-sequencing results indicates that σ(B)-dependent regulation of gene expression contributes to resilience, i.e., the coordination of complex networks responsive to environmental changes. This review explores contributions of σ(B) to resilience in Bacillus, Listeria, and Staphylococcus and illustrates recently described regulatory functions of σ(B). PMID:27208112

  13. Design and characterization of novel antimicrobial peptides, R-BP100 and RW-BP100, with activity against Gram-negative and Gram-positive bacteria.

    PubMed

    Torcato, Inês M; Huang, Yen-Hua; Franquelim, Henri G; Gaspar, Diana; Craik, David J; Castanho, Miguel A R B; Troeira Henriques, Sónia

    2013-03-01

    BP100 is a short cationic antimicrobial peptide with a mechanism of action dependent on peptide-lipid interactions and microbial surface charge neutralization. Although active against Gram-negative bacteria, BP100 is inactive against Gram-positive bacteria. In this study we report two newly designed BP100 analogues, RW-BP100 and R-BP100 that have the Tyr residue replaced with a Trp and/or the Lys residues replaced with an Arg. The new analogues in addition to being active against Gram-negative bacteria, possess activity against all tested Gram-positive bacteria. Mechanistic studies using atomic force microscopy, surface plasmon resonance and fluorescence methodologies reveal that the antibacterial efficiency follows the affinity for bacterial membrane. The studies suggest that the activity of BP100 and its analogues against Gram-negative bacteria is mainly driven by electrostatic interactions with the lipopolysaccharide layer and is followed by binding to and disruption of the inner membrane, whereas activity against Gram-positive bacteria, in addition to electrostatic attraction to the exposed lipoteichoic acids, requires an ability to more deeply insert in the membrane environment, which is favoured with Arg residues and is facilitated in the presence of a Trp residue. Knowledge on the mechanism of action of these antimicrobial peptides provides information that assists in the design of antimicrobials with higher efficacy and broader spectra of action, but also on the design of peptides with higher specificity if required. PMID:23246973

  14. Genetic characteristics of Streptococcus dysgalactiae isolated from cage cultured cobia, Rachycentron canadum (L.).

    PubMed

    Tsai, M-A; Wang, P-C; Yoshida, T; Chen, S-C

    2015-12-01

    Disease outbreaks occurred during 2007-2013 in Taiwan with 2.5-10% mortality among the cage cultured cobia, Rachycentron canadum (L.), characterized by the presence of polyserositis, pericarditis and peritonitis. The micro-organisms isolated from internal organs were Gram-positive cocci. The isolates were confirmed as Streptococcus dysgalactiae by a polymerase chain reaction assay that yielded the expected specific 259 bp amplicon. Additionally, partial sequence of the 16S-23S rDNA intergenic spacer region of the GCS strain isolates from fish was also compared and produced 100% sequence identity with S. dysgalactiae (GenBank accession number AB252398). The genetic characterization was then determined by pulsed-field gel electrophoresis (PFGE) analysis. Based on PFGE, the Apa I or Sma I digestion patterns of chromosomal DNA of these isolates were grouped into three main clusters. Taiwanese strains were divided into two clusters, and the tet(M) gene was detected in cluster 1 (pulsotypes: A1-A2 and S1-S3), but not in cluster 2 strains (pulsotypes: A3-A4 and S4-S5). Three Japanese strains from amberjack, Seriola dumerili (Risso), were grouped into cluster 3 (pulsotypes: A5-A7 and S6-S8) and displayed no mortality to cobia in the challenge experiment. Conversely, Taiwanese strains from cobia and snubnose pompano, Trachinotus blochii (L.), displayed a mortality rate of 50-87.5% in cobia. PMID:25087459

  15. Fructose Utilization in Lactococcus lactis as a Model for Low-GC Gram-Positive Bacteria: Its Regulator, Signal, and DNA-Binding Site

    PubMed Central

    Barrière, Charlotte; Veiga-da-Cunha, Maria; Pons, Nicolas; Guédon, Eric; van Hijum, Sacha A. F. T.; Kok, Jan; Kuipers, Oscar P.; Ehrlich, Dusko S.; Renault, Pierre

    2005-01-01

    In addition to its role as carbon and energy source, fructose metabolism was reported to affect other cellular processes, such as biofilm formation by streptococci and bacterial pathogenicity in plants. Fructose genes encoding a 1-phosphofructokinase and a phosphotransferase system (PTS) fructose-specific enzyme IIABC component reside commonly in a gene cluster with a DeoR family regulator in various gram-positive bacteria. We present a comprehensive study of fructose metabolism in Lactococcus lactis, including a systematic study of fru mutants, global messenger analysis, and a molecular characterization of its regulation. The fru operon is regulated at the transcriptional level by both FruR and CcpA and at the metabolic level by inducer exclusion. The FruR effector is fructose-1-phosphate (F1P), as shown by combined analysis of transcription and measurements of the intracellular F1P pools in mutants either unable to produce this metabolite or accumulating it. The regulation of the fru operon by FruR requires four adjacent 10-bp direct repeats. The well-conserved organization of the fru promoter region in various low-GC gram-positive bacteria, including CRE boxes as well as the newly defined FruR motif, suggests that the regulation scheme defined in L. lactis could be applied to these bacteria. Transcriptome profiling of fruR and fruC mutants revealed that the effect of F1P and FruR regulation is limited to the fru operon in L. lactis. This result is enforced by the fact that no other targets for FruR were found in the available low-GC gram-positive bacteria genomes, suggesting that additional phenotypical effects due to fructose metabolism do not rely directly on FruR control, but rather on metabolism. PMID:15901699

  16. In vitro metabolism of 2,2'-diaminopimelic acid from gram-positive and gram-negative bacterial cells by ruminal protozoa and bacteria.

    PubMed Central

    Denholm, A M; Ling, J R

    1989-01-01

    Bacillus megaterium GW1 and Escherichia coli W7-M5 were specifically radiolabeled with 2,2'-diamino[G-3H]pimelic acid [( 3H]DAP) as models of gram-positive and gram-negative bacteria, respectively. These radiolabeled bacterial mutants were incubated alone (control) and with mixed ruminal bacteria or protozoa, and the metabolic processes, rates, and patterns of radiolabeled products released from them were studied. Control incubations revealed an inherent difference between the two substrates; gram-positive supernatants consistently contained 5% radioactivity, whereas even at 0 h, those from the gram-negative mutant released 22%. Incubations with ruminal microorganisms showed that the two mutants were metabolized differently and that protozoa were the major effectors of their metabolism. Protozoa exhibited differential rates of engulfment (150 B. megaterium GW1 and 4,290 E. coli W7-M5 organisms per protozoan per h), and they extensively degraded [3H]DAP-labeled B. megaterium GW1 at rates up to nine times greater than those of ruminal bacteria. By contrast, [3H]DAP-labeled E. coli W7-M5 degradation by either ruminal bacteria or ruminal protozoa was more limited. These fundamental differences in the metabolism of the two mutants, especially by ruminal protozoa, were reflected in the patterns and rates of radiolabeled metabolites produced; many were rapidly released from [3H]DAP-labeled B. megaterium GW1, whereas few were slowly released from [3H]DAP-labeled E. coli W7-M5. Most radiolabeled products derived from [3H]DAP-labeled B. megaterium GW1 were peptides of bacterial peptidoglycan origin. The ruminal metabolism of DAP-containing gram-positive and gram-negative bacteria, even with the same peptidoglycan chemotype, is thus likely to be profoundly different.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2495759

  17. Identification of proteins capable of metal reduction from the proteome of the Gram-positive bacterium Desulfotomaculum reducens MI-1 using an NADH-based activity assay

    SciTech Connect

    Otwell, Annie E.; Sherwood, Roberts; Zhang, Sheng; Nelson, Ornella D.; Li, Zhi; Lin, Hening; Callister, Stephen J.; Richardson, Ruth E.

    2015-01-01

    Metal reduction capability has been found in numerous species of environmentally abundant Gram-positive bacteria. However, understanding of microbial metal reduction is based almost solely on studies of Gram-negative organisms. In this study, we focus on Desulfotomaculum reducens MI-1, a Gram-positive metal reducer whose genome lacks genes with similarity to any characterized metal reductase. D. reducens has been shown to reduce not only Fe(III), but also the environmentally important contaminants U(VI) and Cr(VI). By extracting, separating, and analyzing the functional proteome of D. reducens, using a ferrozine-based assay in order to screen for chelated Fe(III)-NTA reduction with NADH as electron donor, we have identified proteins not previously characterized as iron reductases. Their function was confirmed by heterologous expression in E. coli. These are the protein NADH:flavin oxidoreductase (Dred_2421) and a protein complex composed of oxidoreductase FAD/NAD(P)-binding subunit (Dred_1685) and dihydroorotate dehydrogenase 1B (Dred_1686). Dred_2421 was identified in the soluble proteome and is predicted to be a cytoplasmic protein. Dred_1685 and Dred_1686 were identified in both the soluble as well as the insoluble (presumably membrane) protein fraction, suggesting a type of membrane-association, although PSORTb predicts both proteins are cytoplasmic. Furthermore, we show that these proteins have the capability to reduce soluble Cr(VI) and U(VI) with NADH as electron donor. This study is the first functional proteomic analysis of D. reducens, and one of the first analyses of metal and radionuclide reduction in an environmentally relevant Gram-positive bacterium.

  18. Oxidative stress-mediated selective antimicrobial ability of nano-VO2 against Gram-positive bacteria for environmental and biomedical applications.

    PubMed

    Li, Jinhua; Zhou, Huaijuan; Wang, Jiaxing; Wang, Donghui; Shen, Ruxiang; Zhang, Xianlong; Jin, Ping; Liu, Xuanyong

    2016-06-01

    Vanadium dioxide (VO2) is a unique thermochromic material as a result of its semiconductor-metal transition, holding great promise for energy-saving intelligent windows. Herein, pure nano-VO2 from discrete nanoparticles to continuous films were successfully deposited on quartz glass by controlling the sputtering parameters. It was demonstrated that, for Gram-positive S. aureus and S. epidermidis, the nano-VO2 could effectively disrupt bacteria morphology and membrane integrity, and eventually cause death. By contrast, the nano-VO2 did not exhibit significant toxicity towards Gram-negative E. coli and P. aeruginosa. To our knowledge, this is the first report on a selective antimicrobial effect of nano-VO2 materials on Gram-positive bacteria. Based on the experimental results, a plausible mechanism was proposed for the antimicrobial selectivity, which might originate from the different sensitivity of Gram-positive and Gram-negative bacteria to intracellular reactive oxygen species (ROS) level. Elevated intracellular ROS levels exceed the threshold that bacteria can self-regulate to maintain cellular redox homeostasis and thus cause oxidative stress, which can be alleviated by the intervention of glutathione (GSH) antioxidant. In addition, nano-VO2 did not produce significant cytotoxicity (hemolysis) against human erythrocytes within 12 h. Meanwhile, potential cytotoxicity against HIBEpiC revealed a time- and dose-dependent behavior that might be controlled and balanced by careful design. The findings in the present work may contribute to understanding the antimicrobial behavior of nano-VO2, and to expanding the new applications of VO2-based nanomaterials in environmental and biomedical fields. PMID:27240639

  19. Oxidative stress-mediated selective antimicrobial ability of nano-VO2 against Gram-positive bacteria for environmental and biomedical applications

    NASA Astrophysics Data System (ADS)

    Li, Jinhua; Zhou, Huaijuan; Wang, Jiaxing; Wang, Donghui; Shen, Ruxiang; Zhang, Xianlong; Jin, Ping; Liu, Xuanyong

    2016-06-01

    Vanadium dioxide (VO2) is a unique thermochromic material as a result of its semiconductor-metal transition, holding great promise for energy-saving intelligent windows. Herein, pure nano-VO2 from discrete nanoparticles to continuous films were successfully deposited on quartz glass by controlling the sputtering parameters. It was demonstrated that, for Gram-positive S. aureus and S. epidermidis, the nano-VO2 could effectively disrupt bacteria morphology and membrane integrity, and eventually cause death. By contrast, the nano-VO2 did not exhibit significant toxicity towards Gram-negative E. coli and P. aeruginosa. To our knowledge, this is the first report on a selective antimicrobial effect of nano-VO2 materials on Gram-positive bacteria. Based on the experimental results, a plausible mechanism was proposed for the antimicrobial selectivity, which might originate from the different sensitivity of Gram-positive and Gram-negative bacteria to intracellular reactive oxygen species (ROS) level. Elevated intracellular ROS levels exceed the threshold that bacteria can self-regulate to maintain cellular redox homeostasis and thus cause oxidative stress, which can be alleviated by the intervention of glutathione (GSH) antioxidant. In addition, nano-VO2 did not produce significant cytotoxicity (hemolysis) against human erythrocytes within 12 h. Meanwhile, potential cytotoxicity against HIBEpiC revealed a time- and dose-dependent behavior that might be controlled and balanced by careful design. The findings in the present work may contribute to understanding the antimicrobial behavior of nano-VO2, and to expanding the new applications of VO2-based nanomaterials in environmental and biomedical fields.

  20. Evaluation of the in vitro growth of urinary tract infection-causing gram-negative and gram-positive bacteria in a proposed synthetic human urine (SHU) medium.

    PubMed

    Ipe, Deepak S; Ulett, Glen C

    2016-08-01

    Bacteriuria is a hallmark of urinary tract infection (UTI) and asymptomatic bacteriuria (ABU), which are among the most frequent infections in humans. A variety of gram-negative and gram-positive bacteria are associated with these infections but Escherichia coli contributes up to 80% of cases. Multiple bacterial species including E. coli can grow in human urine as a means to maintain colonization during infections. In vitro bacteriuria studies aimed at modeling microbial growth in urine have utilized various compositions of synthetic human urine (SHU) and a Composite SHU formulation was recently proposed. In this study, we sought to validate the recently proposed Composite SHU as a medium that supports the growth of several bacterial species that are known to grow in normal human urine and/or artificial urine. Comparative growth assays of gram-negative and gram-positive bacteria E. coli, Pseudomonas aeruginosa, Proteus mirabilis, Streptococcus agalactiae, Staphylococcus saprophyticus and Enterococcus faecalis were undertaken using viable bacterial count and optical density measurements over a 48h culture period. Three different SHU formulations were tested in various culture vessels, shaking conditions and volumes and showed that Composite SHU can support the robust growth of gram-negative bacteria but requires supplementation with 0.2% yeast extract to support the growth of gram-positive bacteria. Experiments are also presented that show an unexpected but major influence of P. mirabilis towards the ability to measure bacterial growth in generally accepted multiwell assays using absorbance readings, predicted to have a basis in the release of volatile organic compound(s) from P. mirabilis during growth in Composite SHU medium. This study represents an essential methodological validation of a more chemically defined type of synthetic urine that can be applied to study mechanisms of bacteriuria and we conclude will offer a useful in vitro model to investigate the

  1. Clonal Diversity in Multi Drug Resistant (MDR) Enterococci Isolated from Fecal Normal Flora.

    PubMed

    Hasannejad Bibalan, Meysam; Eshaghi, Morteza; Sadeghi, Javad; Asadian, Mahla; Narimani, Tahmineh; Talebi, Malihe

    2015-01-01

    Enterococci are Gram positive and catalase- negative cocci that are found in the gastrointestinal tract of mammals and birds, and are readily isolated from soil, surface and waters. The aim of this study was to discriminate between Enterococcus isolates based on repetitive element sequence based -PCR (Rep-PCR) with the BOXA2R primer and their antibiotics profile. Enterococci isolates were obtained from 180 fecal samples. The isolates were identified by biochemical reaction and specific identification was confirmed by PCR with species specific primers. All isolates were subjected to Rep typing and antimicrobial susceptibility tests. Rep-PCR analysis of 180 isolates revealed 93 REP types with forty-five single types (ST1 to ST45) and forty-eight common types (CT1 to 48). Antibiotic susceptibility tests exhibited that 53 (29.4%), 43 (23.8%), 11 (6.1%) and 9 (5%) were resistant to erythromycin, tetracycline, gentamicin and ciprofloxacin respectively but among the isolates, sixteen were multi drug resistant (MDR). These MDR isolates showed 11 Rep types with seven single types and four common types. In addition, 81.2% of MDR isolates were from male subjects and the average age of these persons was more than fifty years. This study showed that 56.2% of MDR isolates were homogeneous with 95 % similarity, and high rate of resistance to tetracycline and erythromycin (81.2%) were observed in these isolates. The concern about these normal flora isolates are the pathogenic potential of these bacteria through the horizontal transfer of antibiotic resistance and virulence genes. PMID:27014649

  2. Pleural effusion adenosine deaminase: a candidate biomarker to discriminate between Gram-negative and Gram-positive bacterial infections of the pleural space

    PubMed Central

    Li, Ruolin; Wang, Junli; Wang, Xinfeng; Wang, Maoshui

    2016-01-01

    OBJECTIVES: Delay in the treatment of pleural infection may contribute to its high mortality. In this retrospective study, we aimed to evaluate the diagnostic accuracy of pleural adenosine deaminase in discrimination between Gram-negative and Gram-positive bacterial infections of the pleural space prior to selecting antibiotics. METHODS: A total of 76 patients were enrolled and grouped into subgroups according to Gram staining: 1) patients with Gram-negative bacterial infections, aged 53.2±18.6 years old, of whom 44.7% had empyemas and 2) patients with Gram-positive bacterial infections, aged 53.5±21.5 years old, of whom 63.1% had empyemas. The pleural effusion was sampled by thoracocentesis and then sent for adenosine deaminase testing, biochemical testing and microbiological culture. The Mann-Whitney U test was used to examine the differences in adenosine deaminase levels between the groups. Correlations between adenosine deaminase and specified variables were also quantified using Spearman’s correlation coefficient. Moreover, receiver operator characteristic analysis was performed to evaluate the diagnostic accuracy of pleural effusion adenosine deaminase. RESULTS: Mean pleural adenosine deaminase levels differed significantly between Gram-negative and Gram-positive bacterial infections of the pleural space (191.8±32.1 U/L vs 81.0±16.9 U/L, p<0.01). The area under the receiver operator characteristic curve was 0.689 (95% confidence interval: 0.570, 0.792, p<0.01) at the cutoff value of 86 U/L. Additionally, pleural adenosine deaminase had a sensitivity of 63.2% (46.0-78.2%); a specificity of 73.7% (56.9-86.6%); positive and negative likelihood ratios of 2.18 and 0.50, respectively; and positive and negative predictive values of 70.6% and 66.7%, respectively. CONCLUSIONS: Pleural effusion adenosine deaminase is a helpful alternative biomarker for early and quick discrimination of Gram-negative from Gram-positive bacterial infections of the pleural space

  3. (1)H, (15)N and (13)C chemical shift assignment of the Gram-positive conjugative transfer protein TraHpIP501.

    PubMed

    Fercher, Christian; Keller, Walter; Zangger, Klaus; Helge Meyer, N

    2016-04-01

    Conjugative transfer of DNA represents the most important transmission pathway in terms of antibiotic resistance and virulence gene dissemination among bacteria. TraH is a putative transfer protein of the type IV secretion system (T4SS) encoded by the Gram-positive (G+) conjugative plasmid pIP501. This molecular machine involves a multi-protein core complex spanning the bacterial envelope thereby serving as a macromolecular secretion channel. Here, we report the near complete (1)H, (13)C and (15)N resonance assignment of a soluble TraH variant comprising the C-terminal domain. PMID:26559076

  4. Physico-Chemical-Managed Killing of Penicillin-Resistant Static and Growing Gram-Positive and Gram-Negative Vegetative Bacteria

    NASA Technical Reports Server (NTRS)

    Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor); Farris, III, Alex F. (Inventor)

    2012-01-01

    Systems and methods for the use of compounds from the Hofmeister series coupled with specific pH and temperature to provide rapid physico-chemical-managed killing of penicillin-resistant static and growing Gram-positive and Gram-negative vegetative bacteria. The systems and methods represent the more general physico-chemical enhancement of susceptibility for a wide range of pathological macromolecular targets to clinical management by establishing the reactivity of those targets to topically applied drugs or anti-toxins.

  5. A phylogenetic comparison of the 16S rRNA sequence of the fish pathogen, Renibacterium salmoninarum, to gram-positive bacteria.

    PubMed

    Gutenberger, S K; Giovannoni, S J; Field, K G; Fryer, J L; Rohovec, J S

    1991-01-15

    The 16S rRNA of Renibacterium salmoninarum, the causative agent of bacterial kidney disease in salmonids, was sequenced by reverse transcriptase to produce a nearly complete sequence (97%) of 1475 nucleotides. Phylogenetic comparisons to seventeen genera and signature sequence analysis indicated that R. salmoninarum was a member of the high G + C Gram-positive eubacterial subdivision although the reported G + C value is only 53%. A phylogenetic tree details the relationship of R. salmoninarum to ten actinomycetes from diverse environments. PMID:1709893

  6. The Effect of Bicarbonate on the Microbial Dissolution of Autunite Mineral in the Presence of Gram-Positive Bacteria

    SciTech Connect

    Sepulveda-Medina, Paola; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel

    2015-06-01

    Bacteria are key players in the processes that govern fate and transport of contaminants. The uranium release from Na and Ca-autunite by Arthrobacter oxydans strain G968 was evaluated in the presence of bicarbonate ions. This bacterium was previously isolated from Hanford Site soil and in earlier prescreening tests demonstrated low tolerance to U(VI) toxicity compared to other A.oxydans isolates. Experiments were conducted using glass serum bottles as mixed bioreactors and sterile 6-well cell culture plates with inserts separating bacteria cells from mineral solids. Reactors containing phosphorus-limiting media were amended with bicarbonate ranging between 0-10 mM and metaautunite solids to provide a U(VI) concentration of 4.4 mmol/L. Results showed that in the presence of bicarbonate, A.oxydans G968 was able to enhance the release of U(VI) from Na and Ca autunite at the same capacity as other A.oxydans isolates with relatively high tolerance to U(VI). The effect of bacterial strains on autunite dissolution decreases as the concentration of bicarbonate increases. The results illustrate that direct interaction between the bacteria and the mineral is not necessary to result in U (VI) biorelease from autunite. The formation of secondary calcium-phosphate mineral phases on the surface of the mineral during the dissolution can ultimately reduce the natural autunite mineral contact area, which bacterial cells can access. This thereby reduces the concentration of uranium released into the solution. This study provides a better understanding of the interactions between meta-autunite and microbes in conditions mimicking arid and semiarid subsurface environments of western U.S.

  7. The effect of bicarbonate on the microbial dissolution of autunite mineral in the presence of gram-positive bacteria.

    PubMed

    Sepulveda-Medina, Paola M; Katsenovich, Yelena P; Wellman, Dawn M; Lagos, Leonel E

    2015-06-01

    Bacteria are key players in the processes that govern fate and transport of contaminants. The uranium release from Na and Ca-autunite by Arthrobacter oxydans strain G968 was evaluated in the presence of bicarbonate ions. This bacterium was previously isolated from Hanford Site soil and in earlier prescreening tests demonstrated low tolerance to U(VI) toxicity compared to other A. oxydans isolates. Experiments were conducted using glass serum bottles as mixed bioreactors and sterile 6-well cell culture plates with inserts separating bacteria cells from mineral solids. Reactors containing phosphorus-limiting media were amended with bicarbonate ranging between 0 and 10 mM and meta-autunite solids to provide a U(VI) concentration of 4.4 mmol/L. Results showed that in the presence of bicarbonate, A. oxydans G968 was able to enhance the release of U(VI) from Na and Ca autunite at the same capacity as other A. oxydans isolates with relatively high tolerance to U(VI). The effect of bacterial strains on autunite dissolution decreases as the concentration of bicarbonate increases. The results illustrate that direct interaction between the bacteria and the mineral is not necessary to result in U(VI) biorelease from autunite. The formation of secondary calcium-phosphate mineral phases on the surface of the mineral during the dissolution can ultimately reduce the natural autunite mineral contact area, which bacterial cells can access. This thereby reduces the concentration of uranium released into the solution. This study provides a better understanding of the interactions between meta-autunite and microbes in conditions mimicking arid and semiarid subsurface environments of western U.S. PMID:25827574

  8. Isolation and characterization of anaerobic bacteria for symbiotic recycling of uric acid nitrogen in the gut of various termites.

    PubMed

    Thong-On, Arunee; Suzuki, Katsuyuki; Noda, Satoko; Inoue, Jun-ichi; Kajiwara, Susumu; Ohkuma, Moriya

    2012-01-01

    Recycling of the nitrogenous waste uric acid (UA) of wood-feeding termites by their gut bacteria is one of the significant aspects of symbiosis for the conservation of nitrogen sources. Diverse anaerobic UA-degrading bacteria comprising 16 species were isolated from the gut of eight termite species, and were assigned to Clostridia, Enterobacteriaceae, and low G+C Gram-positive cocci. UA-degrading Clostridia had never been isolated from termite guts. UA-degrading ability was sporadically distributed among phylogenetically various culturable anaerobic bacteria from termite guts. A strain of Clostridium sp., which was commonly isolated from three termite species and represented a probable new species in cluster XIVa of clostridia, utilized UA as a nitrogen source but not as a sole carbon and energy source. This feature is in clear contrast to that of well-studied purinolytic clostridia or previously isolated UA degraders from termite guts, which also utilize UA as a sole carbon and energy source. Ammonia is the major nitrogenous product of UA degradation. Various purines stimulated the growth of this strain when added to an otherwise growth-limiting, nitrogen poor medium. The bacterial species involved the recycling of UA nitrogen in the gut microbial community of termites are more diverse in terms of both taxonomy and nutritional physiology than previously recognized. PMID:22791052

  9. Design, synthesis and biological evaluation of 4-benzoyl-1-dichlorobenzoylthiosemicarbazides as potent Gram-positive antibacterial agents.

    PubMed

    Paneth, Agata; Plech, Tomasz; Kaproń, Barbara; Hagel, Dominika; Kosikowska, Urszula; Kuśmierz, Edyta; Dzitko, Katarzyna; Paneth, Piotr

    2016-01-01

    Twelve 4-benzoyl-1-dichlorobenzoylthiosemicarbazides have been tested as potential antibacterials. All the compounds had MICs between 0.49 and 15.63 µg/ml toward Micrococcus luteus, Bacillus cereus, Bacillus subtilis and Staphylococcus epidermidis indicating, in most cases, equipotent or even more effective action than cefuroxime. In order to clarify if the observed antibacterial effects are universal, further research were undertaken to test inhibitory potency of two most potent compounds 3 and 11 on clinical isolates of Staphylococcus aureus. Compound 11 inhibited the growth of methicillin-sensitive S. aureus (MSSA) at MICs of 1.95-7.81 µg/ml, methicillin-resistant S. aureus (MRSA) at MICs of 0.49-1.95 µg/ml and MDR-MRSA at MIC of 0.98 and 3.90 µg/ml, respectively. Finally, inhibitory efficacy of 3 and 11 on planktonic cells and biofilms formation in clinical isolates of S. aureus and Haemophilus parainfluenzae was tested. The majority of cells in biofilm populations of MSSA and MRSA were eradicated at low level of 3, with MBICs in the range of 7.82-15.63 µg/ml. PMID:25897586

  10. The RepA_N replicons of Gram-positive bacteria: a family of broadly distributed but narrow host range plasmids

    PubMed Central

    Weaver, Keith E.; Kwong, Stephen M.; Firth, Neville; Francia, Maria Victoria

    2009-01-01

    The pheromone-responsive conjugative plasmids of Enterococcus faecalis and the multi-resistance plasmids pSK1 and pSK41 of Staphylococcus aureus are among the best studied plasmids native to Gram-positive bacteria. Although these plasmids seem largely restricted to their native hosts, protein sequence comparison of their replication initiator proteins indicates that they are clearly related. Homology searches indicate that these replicons are representatives of a large family of plasmids and a few phage that are widespread among the low G+C Gram-positive bacteria. We propose to name this family the RepA_N family of replicons after the annotated conserved domain that the initiator protein contains. Detailed sequence comparisons indicate that the initiator protein phylogeny is largely congruent with that of the host, suggesting that the replicons have evolved along with their current hosts and that intergeneric transfer has been rare. However, related proteins were identified on chromosomal regions bearing characteristics indicative of ICE elements, and the phylogeny of these proteins displayed evidence of more frequent intergeneric transfer. Comparison of stability determinants associated with the RepA_N replicons suggests that they have a modular evolution as has been observed in other plasmid families. PMID:19100285

  11. Current Concepts in Antimicrobial Therapy Against Select Gram-Positive Organisms: Methicillin-Resistant Staphylococcus aureus, Penicillin-Resistant Pneumococci, and Vancomycin-Resistant Enterococci

    PubMed Central

    Rivera, Ana Maria; Boucher, Helen W.

    2011-01-01

    Gram-positive bacteria cause a broad spectrum of disease in immunocompetent and immunocompromised hosts. Despite increasing knowledge about resistance transmission patterns and new antibiotics, these organisms continue to cause significant morbidity and mortality, especially in the health care setting. Methicillin-resistant Staphylococcus aureus poses major problems worldwide as a cause of nosocomial infection and has emerged as a cause of community-acquired infections. This change in epidemiology affects choices of empirical antibiotics for skin and skin-structure infections and community-acquired pneumonia in many settings. Throughout the world, the treatment of community-acquired pneumonia and other respiratory tract infections caused by penicillin-resistant Streptococcus pneumoniae has been complicated by resistance to β-lactam and macrolide antibacterial drugs. Vancomycin-resistant enterococci are a major cause of infection in the hospital setting and remain resistant to treatment with most standard antibiotics. Treatment of diseases caused by resistant gram-positive bacteria requires appropriate use of available antibiotics and stewardship to prolong their effectiveness. In addition, appropriate and aggressive infection control efforts are vital to help prevent the spread of resistant pathogens. PMID:22134942

  12. Catellicoccus marimammalium gen. nov., sp. nov., a novel Gram-positive, catalase-negative, coccus-shaped bacterium from porpoise and grey seal.

    PubMed

    Lawson, Paul A; Collins, Matthew D; Falsen, Enevold; Foster, Geoffrey

    2006-02-01

    Two strains of an unknown Gram-positive, catalase-negative, facultatively anaerobic, coccus-shaped bacterium, originating from a porpoise and a grey seal, were characterized using phenotypic, biochemical and molecular phylogenetic methods. Chemical studies revealed the presence of a cell-wall murein based on L-lysine (type L-lys-gly-D-Asp) and a DNA G+C content of 38 mol%. Comparative 16S rRNA gene sequencing showed that this unidentified coccus-shaped organism formed a hitherto unknown subline closely related to, albeit distinct from, a number of other catalase-negative genera which included Enterococcus, Melissococcus, Tetragenococcus and Vagococcus. Other known Gram-positive, catalase-negative taxa were more distantly related. Tree-branching considerations and sequence divergence values of >6% with recognized taxa were indicative of this novel bacterium representing a separate genus. Based on phenotypic and phylogenetic evidence, it is proposed that this unknown bacterium, recovered from a porpoise and a grey seal, be classified as a novel genus and species, Catellicoccus marimammalium gen. nov., sp. nov. The type strain is M35/04/3T (=CCUG 49459T=CIP 108575T). PMID:16449452

  13. Daptomycin antibiotic lock therapy for hemodialysis patients with Gram-positive bloodstream infections following use of tunneled, cuffed hemodialysis catheters: retrospective single center analysis.

    PubMed

    Yen, Hung-Wen; Yang, Wu-Chang; Tarng, Der-Cherng; Yang, Chih-Yu; Chuang, Chiao-Lin; Huang, Ling-Ju; Lin, Pei-Yu; Wang, Chih-Chun; Li, Szu-Yuan

    2016-04-01

    Catheter-related blood stream infection (CRBSI) is a major complication in hemodialysis patients. We assessed the efficacy of systemic daptomycin (DPT) plus DPT antibiotic lock therapy (DPT-ALT) for catheter salvage in patients with Gram-positive CRBSIs. This is a retrospective study of hemodialysis patients with tunneled and cuffed hemodialysis catheters. All patients were from a single institution in Taipei and received systemic DPT plus DPT-ALT for the treatment of Gram-positive CRBSI. Successful resolution of CRBSI was implemented. Resolution of fever within 48 hours, negative result of repeated blood cultures after resolution of fever, no clinical evidence of CRBSI relapse and no need for catheter removal were measured. Fifteen hemodialysis patients received DPT-ALT for CRBSI, nine with coagulase-negative Staphylococcus (CONS), two with methicillin-resistant Staphylococcus aureus (MRSA), three with methicillin-sensitive Staphylococcus aureus (MSSA) and one with polymicrobial infections. Systemic DPT plus DPT-ALT cured 11 patients (73.3%). Treatment failed in all three MRSA cases (two with MRSA and one with MRSA + Enterococcus faecalis). Retrospective design and small sample size were the limitations of this study. Systemic DPT plus DPT-ALT appears to be a promising treatment for CRBSI from CONS and MSSA, but not for MRSA CRBSI. Systemic DPT plus DPT-ALT should be considered for patients with CRBSIs caused by certain species. PMID:26549513

  14. Identification of proteins capable of metal reduction from the proteome of the Gram-positive bacterium Desulfotomaculum reducens MI-1 using an NADH-based activity assay

    PubMed Central

    Otwell, A.E.; Sherwood, R.W.; Zhang, S.; Nelson, O.D.; Li, Z.; Lin, H.; Callister, S.J.; Richardson, R.E.

    2015-01-01

    Summary Understanding of microbial metal reduction is based almost solely on studies of Gram-negative organisms. In this study, we focus on Desulfotomaculum reducens MI-1, a Gram-positive metal reducer whose genome lacks genes with similarity to any characterized metal reductase. Using non-denaturing separations and mass spectrometry identification, in combination with a colorimetric screen for chelated Fe(III)-NTA reduction with NADH as electron donor, we have identified proteins from the D. reducens proteome not previously characterized as iron reductases. Their function was confirmed by heterologous expression in E. coli. Furthermore, we show that these proteins have the capability to reduce soluble Cr(VI) and U(VI) with NADH as electron donor. The proteins identified are NADH:flavin oxidoreductase (Dred_2421) and a protein complex composed of oxidoreductase FAD/NAD(P)-binding subunit (Dred_1685) and dihydroorotate dehydrogenase 1B (Dred_1686). Dred_2421 was identified in the soluble proteome and is predicted to be a cytoplasmic protein. Dred_1685 and Dred_1686 were identified in both the soluble as well as the insoluble protein fraction, suggesting a type of membrane-association, although PSORTb predicts both proteins are cytoplasmic. This study is the first functional proteomic analysis of D. reducens and one of the first analyses of metal and radionuclide reduction in an environmentally relevant Gram-positive bacterium. PMID:25389064

  15. N-Glycans on secretory component: mediators of the interaction between secretory IgA and gram-positive commensals sustaining intestinal homeostasis.

    PubMed

    Mathias, Amandine; Corthésy, Blaise

    2011-09-01

    Human beings live in symbiosis with billions of microorganisms colonizing mucosal surfaces. The understanding of the mechanisms underlying this fine-tuned intestinal balance has made significant processes during the last decades. We have recently demonstrated that the interaction of SIgA with Gram-positive bacteria is essentially based on Fab-independent, glycan-mediated recognition. Results obtained using mouse hybridoma- and colostrum-derived secretory IgA (SIgA) consistently show that N-glycans present on secretory component (SC) play a crucial role in the process. Natural coating may involve specific Gram-positive cell wall components, which may explain selective recognition at the molecular level. More widely, the existence of these complexes is involved in the modulation of intestinal epithelial cell (IEC) responses in vitro and the formation of intestinal biofilms. Thus, SIgA may act as one of the pillars in homeostatic maintenance of the microbiota in the gut, adding yet another facet to its multiple roles in the mucosal environment. PMID:22067937

  16. Use of the lactococcal nisA promoter to regulate gene expression in gram-positive bacteria: comparison of induction level and promoter strength.

    PubMed

    Eichenbaum, Z; Federle, M J; Marra, D; de Vos, W M; Kuipers, O P; Kleerebezem, M; Scott, J R

    1998-08-01

    We characterized the regulated activity of the lactococcal nisA promoter in strains of the gram-positive species Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis, and Bacillus subtilis. nisA promoter activity was dependent on the proteins NisR and NisK, which constitute a two-component signal transduction system that responds to the extracellular inducer nisin. The nisin sensitivity and inducer concentration required for maximal induction varied among the strains. Significant induction of the nisA promoter (10- to 60-fold induction) was obtained in all of the species studied at a nisin concentration just below the concentration at which growth is inhibited. The efficiency of the nisA promoter was compared to the efficiencies of the Spac, xylA, and lacA promoters in B. subtilis and in S. pyogenes. Because nisA promoter-driven expression is regulated in many gram-positive bacteria, we expect it to be useful for genetic studies, especially studies with pathogenic streptococci in which no other regulated promoters have been described. PMID:9687428

  17. Comparison of the Immunostimulatory and Proinflammatory Activities of Candidate Gram-Positive Endotoxins, Lipoteichoic Acid, Peptidoglycan, and Lipopeptides in Murine and Human Cells

    PubMed Central

    Kimbrell, Matthew R.; Warshakoon, Hemamali; Cromer, Jens R.; Malladi, Subbalakshmi; Hood, Jennifer D.; Balakrishna, Rajalakshmi; Scholdberg, Tandace A.; David, Sunil A.

    2008-01-01

    1. Summary The role of lipopolysaccharide (LPS) in the pathogenesis of Gram-negative septic shock is well established. The corresponding proinflammatory and immunostimulatory molecule(s) on the Gram-positive bacteria is less well understood, and their identification and characterization would be a key prerequisite in designing specific sequestrants of the Gram-positive endotoxin(s). We report in this paper the comparison of NF-κB-, cytokine- and chemokine-inducing activities of the TLR2 ligands, lipoteichoic acid (LTA), peptidoglycan (PGN), and lipopeptides, to LPS, a prototype TLR4 agonist, in murine macrophage cell-lines as well as in human blood. In murine cells, di- and triacyl liopopeptides are equipotent in their NF-κB inducing activity relative to LPS, but elicit much lower proinflammatory cytokines. However, both LPS and the lipopeptides potently induce the secretion of a pattern of chemokines that is suggestive of the engagement of a TLR4-independent TRIF pathway. In human blood, although the lipopeptides induce p38 MAP kinase phosphorylation and CD11b upregulation in granulocytes at ng/ml concentrations, they do not elicit proinflammatory cytokine production even at very high doses; LTA, however, activates neutrophils and induces cytokine secretion, although its potency is considerably less than that of LPS, presumably due to its binding to plasma proteins. We conclude that, in human blood, the pattern of immunostimulation and proinflammatory mediator production elicited by LTA parallels that of LPS. PMID:18468694

  18. The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for Gram-positive bacteria over erythrocytes

    NASA Astrophysics Data System (ADS)

    Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

    2013-04-01

    Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects.Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34254a

  19. Potentiation of photoinactivation of Gram-positive and Gram-negative bacteria mediated by six phenothiazinium dyes by addition of azide ion

    PubMed Central

    Kasimova, Kamola R; Sadasivam, Magesh; Landi, Giacomo; Sarna, Tadeusz; Hamblin, Michael R.

    2014-01-01

    Antimicrobial photodynamic inactivation (APDI) using phenothiazinium dyes is mediated by reactive oxygen species consisting of a combination of singlet oxygen (quenched by azide), hydroxyl radicals and other reactive oxygen species. We recently showed that addition of sodium azide paradoxically potentiated APDI of Gram-positive and Gram-negative bacteria using methylene blue as the photosensitizer, and this was due to electron transfer to the dye triplet state from azide anion, producing azidyl radical. Here we compare this effect using six different homologous phenothiazinium dyes: methylene blue, toluidine blue O, new methylene blue, dimethylmethylene blue, azure A, and azure B. We found both significant potentiation (up to 2 logs) and also significant inhibition (>3 logs) of killing by adding 10 mM azide depending on Gram classification, washing the dye from the cells, and dye structure. Killing of E. coli was potentiated with all 6 dyes after a wash, while S. aureus killing was only potentiated by MB and TBO with a wash and DMMB with no wash. More lipophilic dyes (higher log P value, such as DMMB) were more likely to show potentiation. We conclude that the Type I photochemical mechanism (potentiation with azide) likely depends on the microenvironment, i.e. higher binding of dye to bacteria. Bacterial dye-binding is thought to be higher with Gram-negative compared to Gram-positive bacteria, when unbound dye has been washed away, and with more lipophilic dyes. PMID:25177833

  20. Comparison of killing of gram-negative and gram-positive bacteria by pure singlet oxygen. [Salmonella typhimurium; Escherichia coli; Sarcina lutea; Staphylococcus aureus; Streptococcus lactis; Streptococcus faecalis

    SciTech Connect

    Dahl, T.A.; Midden, W.R. ); Hartman, P.E. )

    1989-04-01

    Gram-negative and gram-positive bacteria were found to display different sensitivities to pure singlet oxygen generated outside of cells. Killing curves for Salmonella typhimurium and Escherichia coli strains were indicative of multihit killing, whereas curves for Sarcina lutea, Staphylococcus aureus, Streptococcus lactis, and Streptococcus faecalis exhibited single-hit kinetics. The S. typhimurium deep rough strain TA1975, which lacks nearly all of the cell wall lipopolysaccharide coat and manifests concomitant enhancement of penetration by some exogenous substances, responded to singlet oxygen with initially faster inactivation than did the S. typhimurium wild-type strain, although the maximum rates of killing appeared to be quite similar. The structure of the cell wall thus plays an important role in susceptibility to singlet oxygen. The outer membrane-lipopolysaccharide portion of the gram-negative cell wall initially protects the bacteria from extracellular singlet oxygen, although it may also serve as a source for secondary reaction products which accentuate the rates of cell killing. S. typhimurium and E. coli strains lacking the cellular antioxidant, glutathione, showed no difference from strains containing glutathione in response to the toxic effects of singlet oxygen. Strains of Sarcina lutea and Staphylococcus aureus that contained carotenoids, however, were far more resistant to singlet oxygen lethality than were both carotenoidless mutants of the same species and other gram-positive species lacking high levels of protective carotenoids.

  1. Facile synthesis of gold nanoparticles on propylamine functionalized SBA-15 and effect of surface functionality of its enhanced bactericidal activity against gram positive bacteria

    NASA Astrophysics Data System (ADS)

    Bhuyan, Diganta; Gogoi, Animesh; Saikia, Mrinal; Saikia, Ratul; Saikia, Lakshi

    2015-07-01

    The facile synthesis of an SBA-15-pr-+NH3.Au0 nano-hybrid material by spontaneous autoreduction of aqueous chloroaurate anions on propylamine functionalized SBA-15 was successfully demonstrated. The as-synthesized SBA-15-pr-+NH3.Au0 nano-hybrid material was well characterized using low and wide angle x-ray diffraction (XRD), N2 adsorption-desorption isotherms, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX), x-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy and atomic absorption spectroscopy (AAS). The activity of the nano-hybrid material as a potent bactericidal agent was successfully tested against Gram positive/negative bacteria viz. Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The colony killing percentage of Gram positive bacteria was found to be higher than Gram negative bacteria due to the stronger electrostatic interaction between the positively-charged amine functionality of SBA-15 and the negatively charged functionality of the bacterial cell wall.

  2. Comparison of conventional dosing versus continuous-infusion vancomycin therapy for patients with suspected or documented gram-positive infections.

    PubMed Central

    James, J K; Palmer, S M; Levine, D P; Rybak, M J

    1996-01-01

    Ten patients were treated with conventional dosing (CD) and continuous-infusion (CI) vancomycin therapy in this prospective, randomized, crossover study. Patients were randomized to receive either CD or CI therapy for 2 consecutive days and then crossed over to receive the opposite regimen for 2 days. CD therapy consisted of 1 g of vancomycin every 12 h. CI therapy consisted of a 500-mg loading dose followed by 2 g infused over 24 h. Ten serum samples were obtained on the second day of each therapy for pharmacokinetic and pharmacodynamic analyses. Two clinical isolates of Staphylococcus aureus, one methicillin sensitive (MSSA 1199) and one methicillin resistant (MRSA 494), were chosen for pharmacodynamic evaluation of both regimens. The patient demographics (means +/- standard deviations [SD]) were as follows: sex, six males, four females; age, 36 +/- 11 years; and serum creatinine, 0.72 +/- 0.18 mg/dl. Mean pharmacokinetic parameters +/- SD for CD therapy were as follows: elimination rate constant, 0.16 +/- 0.07 h-1; half-life, 5.6 +/- 3.5 h; volume of distribution, 33.7 +/- 25 liters, 0.5 +/- 0.2 liters/kg; maximum concentration in serum, 53.4 +/- 19.3 micrograms/ml; and minimum concentration, 8.4 +/- 5.9 micrograms/ml. The steady-state concentration for CI was 20.2 +/- 11.1 micrograms/ml. Overall, both regimens resulted in the MIC being exceeded 100% of the time. The mean CD trough serum bactericidal titer (SBT) was 1:8, and the average CI SBTs were 1:16 for both isolates. Even though there was no statistically significant difference between CD trough and CI SBTs, the CI SBTs remained > 1:8 for 100% of the time versus 60% of the time for CD therapy. During CI therapy, 20 and 40% of the patients maintained SBTs of > 1:32 throughout the dosing interval for MSSA 1199 and MRSA 494, respectively. During CD therapy, however, only 10% of patients maintained SBTs of > 1:32 during the entire dosing interval for both isolates. The mean areas under the bactericidal titer

  3. Genome analysis of Desulfotomaculum gibsoniae strain GrollT a highly versatile Gram-positive sulfate-reducing bacterium

    PubMed Central

    Kuever, Jan; Visser, Michael; Loeffler, Claudia; Boll, Matthias; Worm, Petra; Sousa, Diana Z.; Plugge, Caroline M.; Schaap, Peter J.; Muyzer, Gerard; Pereira, Ines A.C.; Parshina, Sofiya N.; Goodwin, Lynne A.; Kyrpides, Nikos C.; Detter, Janine; Woyke, Tanja; Chain, Patrick; Davenport, Karen W.; Rohde, Manfred; Spring, Stefan; Klenk, Hans-Peter; Stams, Alfons J.M.

    2014-01-01

    Desulfotomaculum gibsoniae is a mesophilic member of the polyphyletic spore-forming genus Desulfotomaculum within the family Peptococcaceae. This bacterium was isolated from a freshwater ditch and is of interest because it can grow with a large variety of organic substrates, in particular several aromatic compounds, short-chain and medium-chain fatty acids, which are degraded completely to carbon dioxide coupled to the reduction of sulfate. It can grow autotrophically with H2 + CO2 and sulfate and slowly acetogenically with H2 + CO2, formate or methoxylated aromatic compounds in the absence of sulfate. It does not require any vitamins for growth. Here, we describe the features of D. gibsoniae strain GrollT together with the genome sequence and annotation. The chromosome has 4,855,529 bp organized in one circular contig and is the largest genome of all sequenced Desulfotomaculum spp. to date. A total of 4,666 candidate protein-encoding genes and 96 RNA genes were identified. Genes of the acetyl-CoA pathway, possibly involved in heterotrophic growth and in CO2 fixation during autotrophic growth, are present. The genome contains a large set of genes for the anaerobic transformation and degradation of aromatic compounds, which are lacking in the other sequenced Desulfotomaculum genomes. PMID:25197466

  4. Phenotypic Description and Antimicrobial Susceptibilities of Aerococcus sanguinicola Isolates from Human Clinical Samples

    PubMed Central

    Facklam, Richard; Lovgren, Marguerite; Shewmaker, Patricia Lynn; Tyrrell, Gregory

    2003-01-01

    This report describes the clinical sources and phenotypic characterization of 16 isolates of Aerococcus sanguinicola. Sixteen conventional tests were used to describe and differentiate the 16 isolates of A. sanguinicola from 30 strains of Aerococcus viridans, 27 strains of Aerococcus urinae, and a single strain each of Aerococcus christensenii and Aerococcus urinaehominis. The phenotypic characterizations of the type strains for each species and 14 A. sanguinicola isolates were also compared in the two reference laboratories. A. sanguinicola are catalase-negative, vancomycin-susceptible, gram-positive cocci arranged in clusters and tetrads, as are all Aerococcus species except A. christensenii (which is arranged in short chains). All 16 isolates of A. sanguinicola were leucine aminopeptidase and pyrrolidonylarylamidase positive, which is unique to this species among the aerococci. All A. sanguinicola isolates grew in broth containing 6.5% NaCl, hydrolyzed hippurate, and were variable in the bile-esculin test. None of the isolates deaminated arginine or were Voges-Proskauer positive. The type strain of A. sanguinicola was isolated from a blood culture of a patient living in Denmark. Seven additional isolates were from patients living in Canada, all with urinary tract infections (six were female). Eight isolates were from patients living in five different states in the United States; five were from patients with urinary tract infections, and three were from blood cultures of one patient each with pneumonia, suspected endocarditis, and unknown clinical conditions. The antimicrobial susceptibility patterns were unremarkable; all isolates tested were susceptible to penicillin, amoxicillin, cefotaxime, cefuroxime, erythromycin, chloramphenicol, vancomycin, quinupristin-dalfopristin (Synercid), rifampin, linezolid, and tetracycline. Six of the 15 cultures were resistant to ciprofloxacin and levofloxacin, but all 15 strains were susceptible to sparfloxacin. High

  5. Phenotypic description and antimicrobial susceptibilities of Aerococcus sanguinicola isolates from human clinical samples.

    PubMed

    Facklam, Richard; Lovgren, Marguerite; Shewmaker, Patricia Lynn; Tyrrell, Gregory

    2003-06-01

    This report describes the clinical sources and phenotypic characterization of 16 isolates of Aerococcus sanguinicola. Sixteen conventional tests were used to describe and differentiate the 16 isolates of A. sanguinicola from 30 strains of Aerococcus viridans, 27 strains of Aerococcus urinae, and a single strain each of Aerococcus christensenii and Aerococcus urinaehominis. The phenotypic characterizations of the type strains for each species and 14 A. sanguinicola isolates were also compared in the two reference laboratories. A. sanguinicola are catalase-negative, vancomycin-susceptible, gram-positive cocci arranged in clusters and tetrads, as are all Aerococcus species except A. christensenii (which is arranged in short chains). All 16 isolates of A. sanguinicola were leucine aminopeptidase and pyrrolidonylarylamidase positive, which is unique to this species among the aerococci. All A. sanguinicola isolates grew in broth containing 6.5% NaCl, hydrolyzed hippurate, and were variable in the bile-esculin test. None of the isolates deaminated arginine or were Voges-Proskauer positive. The type strain of A. sanguinicola was isolated from a blood culture of a patient living in Denmark. Seven additional isolates were from patients living in Canada, all with urinary tract infections (six were female). Eight isolates were from patients living in five different states in the United States; five were from patients with urinary tract infections, and three were from blood cultures of one patient each with pneumonia, suspected endocarditis, and unknown clinical conditions. The antimicrobial susceptibility patterns were unremarkable; all isolates tested were susceptible to penicillin, amoxicillin, cefotaxime, cefuroxime, erythromycin, chloramphenicol, vancomycin, quinupristin-dalfopristin (Synercid), rifampin, linezolid, and tetracycline. Six of the 15 cultures were resistant to ciprofloxacin and levofloxacin, but all 15 strains were susceptible to sparfloxacin. High

  6. The effect of a cellulose dressing and topical vancomycin on methicillin-resistant Staphylococcus aureus (MRSA) and Gram-positive organisms in chronic wounds: a case series.

    PubMed

    Albaugh, Karen W; Biely, Scott A; Cavorsi, Joseph P

    2013-05-01

    High levels of persistent bacteria may contribute to wound chronicity and delayed healing. A prospective study was conducted to: 1) evaluate the effect of applying vancomycin topically on appropriately cultured chronic lower leg wounds, specifically methicillin-resistant Staphylococcus aureus (MRSA) and Gram-positive bacteria, and 2) evaluate its effect in combination with a cellulose dressing on healing. Twenty-three (23) outpatients (11 men, 12 women, average age 65 years [range 39-89 years]) with lower extremity wounds (15 venous ulcers, six chronic open wounds with a history of diabetes, and two chronic open trauma wounds) averaging 43.58 weeks' (range 5-121 weeks) duration and swab-cultured positive for MRSA or Gram-positive bacteria were provided 1 g vancomycin delivered by a cellulose dressing and changed every 72 hours. Patients served as their own control, and all wounds were debrided once a week. Wound surface area and bacterial and exudate levels were recorded weekly during the 3-week pretreatment period and compared to 3-week treatment period levels. Patients were followed until healed. Mean change in wound surface area was +14.5% (SD 71.91) per week before and -24.6% (SD 13.59) during the vancomycin treatment period (P = 0.014), average exudate levels decreased from 2.75 (range 1-4) to 1.81 (range 0-3) (P = 0.016), and the number of patients with positive wound cultures for MRSA or Gram-positive bacteria decreased from 23 to four after the 3-week study period. All wounds healed after an average of 8.18 weeks (SD 4.76, range 2-17 weeks). The results of this study suggest topical vancomycin applied using a dressing that retains moisture reduces wound bacterial load and may facilitate healing. Randomized, controlled clinical studies to evaluate the effectiveness and efficacy of this treatment modality and explore the relationship between wound culture results and healing are warranted. PMID:23669259

  7. On-column labeling of gram-positive bacteria with a boronic acid functionalized squarylium cyanine dye for analysis by polymer-enhanced capillary transient isotachophoresis.

    PubMed

    Saito, Shingo; Massie, Tara L; Maeda, Takeshi; Nakazumi, Hiroyuki; Colyer, Christa L

    2012-03-01

    A new asymmetric, squarylium cyanine dye functionalized by boronic acid ("SQ-BA") was designed and synthesized for on-capillary labeling of gram-positive bacteria to provide for high sensitivity detection by way of a modified form of capillary electrophoresis with laser induced fluorescence detection (CE-LIF). The CE-based separation employed a polymer-enhanced buffer with capillary transient isotachophoresis in a new hybrid method dubbed "PectI." It was found that the addition of various monosaccharides to SQ-BA in a batch aqueous solution greatly enhanced the emission of the boronic acid functionalized dye by a factor of up to 18.3 at a long wavelength (λ(ex) = 630 nm, λ(em) = 660 nm) with a high affinity constant (K = ~10(2.80) M(-1)) superior to other sugar probes. Semiempirical quantum mechanics calculations suggest that the mechanism for this high enhancement may involve the dissociation of initially nonemissive dye associates (stabilized by an intramolecular hydrogen bond) upon complex formation with sugars. The fluorescence emission of SQ-BA was also significantly enhanced in the presence of a gram-positive bacterial spore, Bacillus globigii (Bg), which serves as a simulant of B. anthracis (or anthrax) and which possesses a peptidoglycan (sugar)-rich spore coat to provide ample sites for interaction with the dye. Several peaks were observed for a pure Bg sample even with polyethyleneoxide (PEO) present in the CE separation buffer, despite the polymer's previously demonstrated ability to focus microoorganisms to a single peak during migration. Likewise, several peaks were observed for a Bg sample when capillary transient isotachophoresis (ctITP) alone was employed. However, the new combination of these techniques as "PectI" dramatically and reproducibly focused the bacteria to a single peak with no staining procedure. Using PectI, the trace detection of Bg spores (corresponding to approximately three cells per injection) along with separation efficiency

  8. Occurrence of ferredoxin:NAD+ oxidoreductase activity and its ion specificity in several Gram-positive and Gram-negative bacteria

    PubMed Central

    Hess, Verena; Gallegos, Rene; Jones, J Andrew; Barquera, Blanca; Malamy, Michael H

    2016-01-01

    A ferredoxin:NAD+ oxidoreductase was recently discovered as a redox-driven ion pump in the anaerobic, acetogenic bacterium Acetobacterium woodii. The enzyme is assumed to be encoded by the rnf genes. Since these genes are present in the genomes of many bacteria, we tested for ferredoxin:NAD+ oxidoreductase activity in cytoplasmic membranes from several different Gram-positive and Gram-negative bacteria that have annotated rnf genes. We found this activity in Clostridium tetanomorphum, Clostridium ljungdahlii, Bacteroides fragilis, and Vibrio cholerae but not in Escherichia coli and Rhodobacter capsulatus. As in A. woodii, the activity was Na+-dependent in C. tetanomorphum and B. fragilis but Na+-independent in C. ljungdahlii and V. cholerae. We deleted the rnf genes from B. fragilis and demonstrated that the mutant has greatly reduced ferredoxin:NAD+ oxidoreductase activity. This is the first genetic proof that the rnf genes indeed encode the reduced ferredoxin:NAD+ oxidoreductase activity. PMID:26793417

  9. Occurrence of ferredoxin:NAD(+) oxidoreductase activity and its ion specificity in several Gram-positive and Gram-negative bacteria.

    PubMed

    Hess, Verena; Gallegos, Rene; Jones, J Andrew; Barquera, Blanca; Malamy, Michael H; Müller, Volker

    2016-01-01

    A ferredoxin:NAD(+) oxidoreductase was recently discovered as a redox-driven ion pump in the anaerobic, acetogenic bacterium Acetobacterium woodii. The enzyme is assumed to be encoded by the rnf genes. Since these genes are present in the genomes of many bacteria, we tested for ferredoxin:NAD(+) oxidoreductase activity in cytoplasmic membranes from several different Gram-positive and Gram-negative bacteria that have annotated rnf genes. We found this activity in Clostridium tetanomorphum, Clostridium ljungdahlii, Bacteroides fragilis, and Vibrio cholerae but not in Escherichia coli and Rhodobacter capsulatus. As in A. woodii, the activity was Na(+)-dependent in C. tetanomorphum and B. fragilis but Na(+)-independent in C. ljungdahlii and V. cholerae. We deleted the rnf genes from B. fragilis and demonstrated that the mutant has greatly reduced ferredoxin:NAD(+) oxidoreductase activity. This is the first genetic proof that the rnf genes indeed encode the reduced ferredoxin:NAD(+) oxidoreductase activity. PMID:26793417

  10. Di-N-Methylation of Anti-Gram-Positive Aminoglycoside-Derived Membrane Disruptors Improves Antimicrobial Potency and Broadens Spectrum to Gram-Negative Bacteria.

    PubMed

    Benhamou, Raphael I; Shaul, Pazit; Herzog, Ido M; Fridman, Micha

    2015-11-01

    The effect of di-N-methylation of bacterial membrane disruptors derived from aminoglycosides (AGs) on antimicrobial activity is reported. Di-N-methylation of cationic amphiphiles derived from several diversely structured AGs resulted in a significant increase in hydrophobicity compared to the parent compounds that improved their interactions with membrane lipids. The modification led to an enhancement in antibacterial activity and a broader antimicrobial spectrum. While the parent compounds were either modestly active or inactive against Gram-negative pathogens, the corresponding di-N-methylated compounds were potent against the tested Gram-negative as well as Gram-positive bacterial strains. The reported modification offers a robust strategy for the development of broad-spectrum membrane-disrupting antibiotics for topical use. PMID:26418734

  11. Histamine induces Toll-like receptor 2 and 4 expression in endothelial cells and enhances sensitivity to Gram-positive and Gram-negative bacterial cell wall components

    PubMed Central

    Talreja, Jaya; Kabir, Mohammad H; Filla, Michael B; Stechschulte, Daniel J; Dileepan, Kottarappat N

    2004-01-01

    Histamine is a major inflammatory molecule released from the mast cell, and is known to activate endothelial cells. However, its ability to modulate endothelial responses to bacterial products has not been evaluated. In this study we determined the ability of histamine to modulate inflammatory responses of endothelial cells to Gram-negative and Gram-positive bacterial cell wall components and assessed the role of Toll-like receptors (TLR) 2 and 4 in the co-operation between histamine and bacterial pathogens. Human umbilical vein endothelial cells (HUVEC) were incubated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or peptidoglycan (PGN) in the presence or absence of histamine, and the expression and release of interleukin-6 (IL-6), and NF-κB translocation were determined. The effect of histamine on the expression of mRNA and proteins for TLR2 and TLR4 was also evaluated. Incubation of HUVEC with LPS, LTA and PGN resulted in marked enhancement of IL-6 mRNA expression and IL-6 secretion. Histamine alone markedly enhanced IL-6 mRNA expression in HUVEC, but it did not stimulate proportional IL-6 release. When HUVEC were incubated with LPS, LTA, or PGN in the presence of histamine marked amplification of both IL-6 production and mRNA expression was noted. HUVEC constitutively expressed TLR2 and TLR4 mRNA and proteins, and these were further enhanced by histamine. The expression of mRNAs encoding MD-2 and MyD88, the accessory molecules associated with TLR signalling, were unchanged by histamine treatment. These results demonstrate that histamine up-regulates the expression of TLR2 and TLR4 and amplifies endothelial cell inflammatory responses to Gram-negative and Gram-positive bacterial components. PMID:15379983

  12. Comparative Proteomic Analysis of Desulfotomaculum reducens MI-1: Insights into the Metabolic Versatility of a Gram-Positive Sulfate- and Metal-Reducing Bacterium

    PubMed Central

    Otwell, Anne E.; Callister, Stephen J.; Zink, Erika M.; Smith, Richard D.; Richardson, Ruth E.

    2016-01-01

    The proteomes of the metabolically versatile and poorly characterized Gram-positive bacterium Desulfotomaculum reducens MI-1 were compared across four cultivation conditions including sulfate reduction, soluble Fe(III) reduction, insoluble Fe(III) reduction, and pyruvate fermentation. Collectively across conditions, we observed at high confidence ~38% of genome-encoded proteins. Here, we focus on proteins that display significant differential abundance on conditions tested. To the best of our knowledge, this is the first full-proteome study focused on a Gram-positive organism cultivated either on sulfate or metal-reducing conditions. Several proteins with uncharacterized function encoded within heterodisulfide reductase (hdr)-containing loci were upregulated on either sulfate (Dred_0633-4, Dred_0689-90, and Dred_1325-30) or Fe(III)-citrate-reducing conditions (Dred_0432-3 and Dred_1778-84). Two of these hdr-containing loci display homology to recently described flavin-based electron bifurcation (FBEB) pathways (Dred_1325-30 and Dred_1778-84). Additionally, we propose that a cluster of proteins, which is homologous to a described FBEB lactate dehydrogenase (LDH) complex, is performing lactate oxidation in D. reducens (Dred_0367-9). Analysis of the putative sulfate reduction machinery in D. reducens revealed that most of these proteins are constitutively expressed across cultivation conditions tested. In addition, peptides from the single multiheme c-type cytochrome (MHC) in the genome were exclusively observed on the insoluble Fe(III) condition, suggesting that this MHC may play a role in reduction of insoluble metals. PMID:26925055

  13. A Systems Biological Approach Reveals Multiple Crosstalk Mechanism between Gram-Positive and Negative Bacterial Infections: An Insight into Core Mechanism and Unique Molecular Signatures

    PubMed Central

    Thangam, Berla; Ahmed, Shiek S. S. J.

    2014-01-01

    Background Bacterial infections remain a major threat and a leading cause of death worldwide. Most of the bacterial infections are caused by gram-positive and negative bacteria, which are recognized by Toll-like receptor (TLR) 2 and 4, respectively. Activation of these TLRs initiates multiple pathways that subsequently lead to effective immune response. Although, both the TLRs share common signaling mechanism yet they may exhibit specificity as well, resulting in the release of diverse range of inflammatory mediators which could be used as candidate biomolecules for bacterial infections. Results We adopted systems biological approach to identify signaling pathways mediated by TLRs to determine candidate molecules associated with bacterial infections. We used bioinformatics concepts, including literature mining to construct protein-protein interaction network, prioritization of TLRs specific nodes using microarray data and pathway analysis. Our constructed PPI network for TLR 2 (nodes: 4091 and edges: 66068) and TLR 4 (node: 4076 and edges: 67898) showed 3207 common nodes, indicating that both the TLRs might share similar signaling events that are attributed to cell migration, MAPK pathway and several inflammatory cascades. Our results propose the potential collaboration between the shared signaling pathways of both the receptors may enhance the immune response against invading pathogens. Further, to identify candidate molecules, the TLRs specific nodes were prioritized using microarray differential expressed genes. Of the top prioritized TLR 2 molecules, 70% were co-expressed. A similar trend was also observed within TLR 4 nodes. Further, most of these molecules were preferentially found in blood plasma for feasible diagnosis. Conclusions The analysis reveals the common and unique mechanism regulated by both the TLRs that provide a broad perspective of signaling events in bacterial infections. Further, the identified candidate biomolecules could potentially aid

  14. Regulation of alkane degradation pathway by a TetR family repressor via an autoregulation positive feedback mechanism in a Gram-positive Dietzia bacterium.

    PubMed

    Liang, Jie-Liang; Nie, Yong; Wang, Miaoxiao; Xiong, Guangming; Wang, Yi-Ping; Maser, Edmund; Wu, Xiao-Lei

    2016-01-01

    n-Alkanes are ubiquitous in nature and serve as important carbon sources for both Gram-positive and Gram-negative bacteria. Hydroxylation of n-alkanes by alkane monooxygenases is the first and most critical step in n-alkane metabolism. However, regulation of alkane degradation genes in Gram-positive bacteria remains poorly characterized. We therefore explored the transcriptional regulation of an alkB-type alkane hydroxylase-rubredoxin fusion gene, alkW1, from Dietzia sp. DQ12-45-1b. The alkW1 promoter was characterized and so was the putative TetR family regulator, AlkX, located downstream of alkW1 gene. We further identified an unusually long 48 bp inverted repeat upstream of alkW1 and demonstrated the binding of AlkX to this operator. Analytical ultracentrifugation and microcalorimetric results indicated that AlkX formed stable dimers in solution and two dimers bound to one operator in a positive cooperative fashion characterized by a Hill coefficient of 1.64 (± 0.03) [k(D)  = 1.06 (± 0.16) μM, k(D) ' = 0.05 (± 0.01) μM]. However, the DNA-binding affinity was disrupted in the presence of long-chain fatty acids (C10-C24), suggesting that AlkX can sense the concentrations of n-alkane degradation metabolites. A model was therefore proposed where AlkX controls alkW1 expression in a metabolite-dependent manner. Bioinformatic analysis revealed that the alkane hydroxylase gene regulation mechanism may be common among Actinobacteria. PMID:26418273

  15. High-Throughput System for the Presentation of Secreted and Surface-Exposed Proteins from Gram-Positive Bacteria in Functional Metagenomics Studies

    PubMed Central

    Dobrijevic, Dragana; Di Liberto, Gaetana; Tanaka, Kosei; de Wouters, Tomas; Dervyn, Rozenn; Boudebbouze, Samira; Binesse, Johan; Blottière, Hervé M.; Jamet, Alexandre; Maguin, Emmanuelle; van de Guchte, Maarten

    2013-01-01

    Complex microbial ecosystems are increasingly studied through the use of metagenomics approaches. Overwhelming amounts of DNA sequence data are generated to describe the ecosystems, and allow to search for correlations between gene occurrence and clinical (e.g. in studies of the gut microbiota), physico-chemical (e.g. in studies of soil or water environments), or other parameters. Observed correlations can then be used to formulate hypotheses concerning microbial gene functions in relation to the ecosystem studied. In this context, functional metagenomics studies aim to validate these hypotheses and to explore the mechanisms involved. One possible approach is to PCR amplify or chemically synthesize genes of interest and to express them in a suitable host in order to study their function. For bacterial genes, Escherichia coli is often used as the expression host but, depending on the origin and nature of the genes of interest and the test system used to evaluate their putative function, other expression systems may be preferable. In this study, we developed a system to evaluate the role of secreted and surface-exposed proteins from Gram-positive bacteria in the human gut microbiota in immune modulation. We chose to use a Gram-positive host bacterium, Bacillus subtilis, and modified it to provide an expression background that behaves neutral in a cell-based immune modulation assay, in vitro. We also adapted an E. coli – B. subtilis shuttle expression vector for use with the Gateway high-throughput cloning system. Finally, we demonstrate the functionality of this host-vector system through the cloning and expression of a flagellin-coding sequence, and show that the expression-clone elicits an inflammatory response in a human intestinal epithelial cell line. The expression host can easily be adapted to assure neutrality in other assay systems, allowing the use of the presented presentation system in functional metagenomics of the gut and other ecosystems. PMID

  16. Comparison of Small-Intestinal Submucosa and Expanded Polytetrafluoroethylene as a Vascular Conduit in the Presence of Gram-Positive Contamination

    PubMed Central

    Shell, Daniel H.; Croce, Martin A.; Cagiannos, Catherine; Jernigan, T Wright; Edwards, Norma; Fabian, Timothy C.

    2005-01-01

    Objective: As a vascular conduit, expanded polytetrafluoroethylene (ePTFE) is susceptible to graft infection with Gram-positive organisms. Biomaterials, such as porcine small-intestinal submucosa (SIS), have been successfully used clinically as tissue substitutes outside the vascular arena. Summary Background Data: In the present study, we compared a small-diameter conduit of SIS to ePTFE in the presence of Gram-positive contamination to evaluate infection resistance, incorporation and remodeling, morphometry, graft patency, and neointimal hyperplasia (NH) development. Methods: Adult male mongrel pigs were randomized to receive either SIS or ePTFE (3-cm length, 6-mm diameter) and further randomized to 1 of 3 groups: Control (no graft inoculation), Staphylococcus aureus, or mucin-producing S epidermidis (each graft inoculation with 108 colonies/mL). Pressure measurements were obtained proximal and distal to the graft to create the iliac/aorta pressure ratio. Morphometric analysis of the neointima and histopathologic examinations was performed. Other outcomes included weekly WBC counts, graft incorporation, and quantitative culture of explanted grafts. Results: Eighteen animals were randomized. All grafts were patent throughout the 6-week study period. Infected SIS grafts had less NH and little change in their iliac/aorta indices compared with infected ePTFE grafts. Quantitative cultures at euthanasia demonstrated no growth in either SIS group compared with 1.7 × 104 colonies for ePTFE S aureus and 6 × 102 for ePTFE S epi (each P < 0.001). All SIS grafts were incorporated. Histology demonstrated remodeling into host artery with smooth muscle and capillary ingrowth in all SIS groups. Scanning electron micrography illustrated smooth and complete endothelialization of all SIS grafts. Conclusions: Compared with ePTFE, SIS induces host tissue remodeling, exhibits a decreased neointimal response to infection, and is resistant to bacterial colonization. SIS may provide a

  17. Photoinactivation of Gram positive and Gram negative bacteria with the antimicrobial peptide (KLAKLAK)(2) conjugated to the hydrophilic photosensitizer eosin Y.

    PubMed

    Johnson, Gregory A; Muthukrishnan, Nandhini; Pellois, Jean-Philippe

    2013-01-16

    We test the hypothesis that the antimicrobial peptide (KLAKLAK)(2) enhances the photodynamic activity of the photosensitizer eosin Y upon conjugation. The conjugate eosin-(KLAKLAK)(2) was obtained by solid-phase peptide synthesis. Photoinactivation assays were performed against the Gram-negative bacteria Escherichia coli , Pseudomonas aeruginosa , and multidrug resistant Acinetobacter baumannii AYE, as well as the Gram-positive bacteria Staphylococcus aureus , and Staphylococcus epidermidis . Partitioning assays were performed with E. coli and S. aureus . Photohemolysis and photokilling assays were also performed to assess the photodynamic activity of the conjugate toward mammalian cells. Eosin-(KLAKLAK)(2) photoinactivates 99.999% of 10(8) CFU/mL of most bacteria tested at a concentration of 1 μM or below. In contrast, neither eosin Y nor (KLAKLAK)(2) cause any significant photoinactivation under similar conditions. The increase in photodynamic activity of the photosensitizer conferred by the antimicrobial peptide is in part due to the fact that (KLAKLAK)(2) promotes the association of eosin Y to bacteria. Eosin-(KLAKLAK)(2) does not significantly associate with red blood cells or the cultured mammalian cell lines HaCaT, COS-7, and COLO 316. Consequently, little photodamage or photokilling is observed with these cells under conditions for which bacterial photoinactivation is achieved. The peptide (KLAKLAK)(2) therefore significantly enhances the photodynamic activity of eosin Y toward both Gram-positive and Gram-negative bacteria while interacting minimally with human cells. Overall, our results suggest that antimicrobial peptides such as (KLAKLAK)(2) might serve as attractive agents that can target photosensitizers to bacteria specifically. PMID:23240991

  18. Cationized Magnetoferritin Enables Rapid Labeling and Concentration of Gram-Positive and Gram-Negative Bacteria in Magnetic Cell Separation Columns

    PubMed Central

    Spencer, J.; Schwarzacher, W.

    2016-01-01

    ABSTRACT In order to identify pathogens rapidly and reliably, bacterial capture and concentration from large sample volumes into smaller ones are often required. Magnetic labeling and capture of bacteria using a magnetic field hold great promise for achieving this goal, but the current protocols have poor capture efficiency. Here, we present a rapid and highly efficient approach to magnetic labeling and capture of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria using cationized magnetoferritin (cat-MF). Magnetic labeling was achieved within a 1-min incubation period with cat-MF, and 99.97% of the labeled bacteria were immobilized in commercially available magnetic cell separation (MACS) columns. Longer incubation times led to more efficient capture, with S. aureus being immobilized to a greater extent than E. coli. Finally, low numbers of magnetically labeled E. coli bacteria (<100 CFU per ml) were immobilized with 100% efficiency and concentrated 7-fold within 15 min. Therefore, our study provides a novel protocol for rapid and highly efficient magnetic labeling, capture, and concentration of both Gram-positive and Gram-negative bacteria. IMPORTANCE Antimicrobial resistance (AMR) is a significant global challenge. Rapid identification of pathogens will retard the spread of AMR by enabling targeted treatment with suitable agents and by reducing inappropriate antimicrobial use. Rapid detection methods based on microfluidic devices require that bacteria are concentrated from large volumes into much smaller ones. Concentration of bacteria is also important to detect low numbers of pathogens with confidence. Here, we demonstrate that magnetic separation columns capture small amounts of bacteria with 100% efficiency. Rapid magnetization was achieved by exposing bacteria to cationic magnetic nanoparticles, and magnetized bacteria were concentrated 7-fold inside the column. Thus, bacterial capture and concentration were achieved

  19. Comparative proteomic analysis of Desulfotomaculum reducens MI-1: Insights into the metabolic versatility of a gram-positive sulfate- and metal-reducing bacterium

    DOE PAGESBeta

    Otwell, Anne E.; Callister, Stephen J.; Zink, Erika M.; Smith, Richard D.; Richardson, Ruth E.

    2016-02-19

    In this study, the proteomes of the metabolically versatile and poorly characterized Gram-positive bacterium Desulfotomaculum reducens MI-1 were compared across four cultivation conditions including sulfate reduction, soluble Fe(III) reduction, insoluble Fe(III) reduction, and pyruvate fermentation. Collectively across conditions, we observed at high confidence ~38% of genome-encoded proteins. Here, we focus on proteins that display significant differential abundance on conditions tested. To the best of our knowledge, this is the first full-proteome study focused on a Gram-positive organism cultivated either on sulfate or metal-reducing conditions. Several proteins with uncharacterized function encoded within heterodisulfide reductase (hdr)-containing loci were upregulated on either sulfatemore » (Dred_0633-4, Dred_0689-90, and Dred_1325-30) or Fe(III)-citrate-reducing conditions (Dred_0432-3 and Dred_1778-84). Two of these hdr-containing loci display homology to recently described flavin-based electron bifurcation (FBEB) pathways (Dred_1325-30 and Dred_1778-84). Additionally, we propose that a cluster of proteins, which is homologous to a described FBEB lactate dehydrogenase (LDH) complex, is performing lactate oxidation in D. reducens (Dred_0367-9). Analysis of the putative sulfate reduction machinery in D. reducens revealed that most of these proteins are constitutively expressed across cultivation conditions tested. In addition, peptides from the single multiheme c-type cytochrome (MHC) in the genome were exclusively observed on the insoluble Fe(III) condition, suggesting that this MHC may play a role in reduction of insoluble metals.« less

  20. In vitro antibacterial activity of AZD0914, a new spiropyrimidinetrione DNA gyrase/topoisomerase inhibitor with potent activity against Gram-positive, fastidious Gram-Negative, and atypical bacteria.

    PubMed

    Huband, Michael D; Bradford, Patricia A; Otterson, Linda G; Basarab, Gregory S; Kutschke, Amy C; Giacobbe, Robert A; Patey, Sara A; Alm, Richard A; Johnstone, Michele R; Potter, Marie E; Miller, Paul F; Mueller, John P

    2015-01-01

    AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, β-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development. PMID:25385112

  1. In Vitro Antibacterial Activity of AZD0914, a New Spiropyrimidinetrione DNA Gyrase/Topoisomerase Inhibitor with Potent Activity against Gram-Positive, Fastidious Gram-Negative, and Atypical Bacteria

    PubMed Central

    Bradford, Patricia A.; Otterson, Linda G.; Basarab, Gregory S.; Kutschke, Amy C.; Giacobbe, Robert A.; Patey, Sara A.; Alm, Richard A.; Johnstone, Michele R.; Potter, Marie E.; Miller, Paul F.; Mueller, John P.

    2014-01-01

    AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, β-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development. PMID:25385112

  2. DEVELOPING GRAM-POSITIVE ETHANOLOGENS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microbial fermentation of almost all the C5 & C6 sugars to biofuel is vital to the overall economic conversion process from lignocellulosic biomass to ethanol. Currently available ethanologens can only use C6, not the mixture of C5 & C6, and relatively low concentrations of ethanol kill the fer...

  3. Staphylococcus massiliensis sp. nov., isolated from a human brain abscess.

    PubMed

    Al Masalma, Mouhamad; Raoult, Didier; Roux, Véronique

    2010-05-01

    Gram-positive, catalase-positive, coagulase-negative, non-motile, non-fermentative and novobiocin-susceptible cocci were isolated from a human brain abscess sample (strain 5402776(T)). This novel strain was analysed by a polyphasic taxonomic approach. The respiratory quinones detected were MK-7 (93 %) and MK-6 (7 %) and the major fatty acids were C(15 : 0) iso (60.5 %), C(17 : 0) iso (8.96 %) C(15 : 0) anteiso (7.93 %) and C(19 : 0) iso (6.78 %). The peptidoglycan type was A3alpha l-Lys-Gly(2-3)-l-Ser-Gly. Based on cellular morphology and biochemical criteria, the new isolate was assigned to the genus Staphylococcus, although it did not correspond to any recognized species. The G+C content of the DNA was 36.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that the new isolate was most closely related to Staphylococcus piscifermentans, Staphylococcus condimenti, Staphylococcus carnosus subsp. carnosus, S. carnosus subsp. utilis and Staphylococcus simulans (97.7 %, 97.6 %, 97.6 %, 97.6 % and 96.5 % sequence similarity, respectively). Comparison of tuf, hsp60, rpoB, dnaJ and sodA gene sequences was also performed. In phylogenetic analysis inferred from tuf, dnaJ and rpoB gene sequence comparisons, strain 5402776(T) clustered with Staphylococcus pettenkoferi (93.7 %, 82.5 % and 89 % sequence similarity, respectively) and on phylogenetic analysis inferred from sodA gene sequence comparisons, it clustered with Staphylococcus chromogenes (82.8 %). On the basis of phenotypic and genotypic data, this isolate represents a novel species for which the name Staphylococcus massiliensis sp. nov. is proposed (type strain 5402776(T)=CCUG 55927(T)=CSUR P23(T)). PMID:19666814

  4. Characterization of 15 selected coccal bacteria isolated from Antarctic rock and soil samples from the McMurdo-Dry Valleys (South-Victoria Land)

    NASA Technical Reports Server (NTRS)

    Siebert, J.; Hirsch, P.; Friedmann, E. I. (Principal Investigator)

    1988-01-01

    Approximately 1500 cultures of microorganisms were isolated from rocks and soils of the Ross Desert (McMurdo-Dry Valleys). From these, 15 coccoid strains were chosen for more detailed investigation. They were characterized by morphological, physiological and chemotaxonomical properties. All isolates were Gram-positive, catalase-positive and nonmotile. Six strains showed red pigmentation and could be identified as members of the genera Micrococcus (M. roseus, M. agilis) or Deinococcus. In spite of their coccoid morphology, the remaining nine strains had to be associated with coryneform bacteria (Arthrobacter, Brevibacterium), because of their cell wall composition and G+C ratios. Most of the strains were psychrotrophic, but one strain was even obligately psychrophilic, with a temperature maximum below 20 degrees C. Red cocci had in vitro pH optima above 9.0 although they generally originated from acid samples. Most isolates showed a preference for sugar alcohols and organic acids, compounds which are commonly known to be released by lichens, molds and algae, the other components of the cryptoendolithic ecosystem. These properties indicate that our strains are autochthonous members of the natural Antarctic microbial population.

  5. Identification of human pathogens isolated from blood using microarray hybridisation and signal pattern recognition

    PubMed Central

    Wiesinger-Mayr, Herbert; Vierlinger, Klemens; Pichler, Rudolf; Kriegner, Albert; Hirschl, Alexander M; Presterl, Elisabeth; Bodrossy, Levente; Noehammer, Christa

    2007-01-01

    Background Pathogen identification in clinical routine is based on the cultivation of microbes with subsequent morphological and physiological characterisation lasting at least 24 hours. However, early and accurate identification is a crucial requisite for fast and optimally targeted antimicrobial treatment. Molecular biology based techniques allow fast identification, however discrimination of very closely related species remains still difficult. Results A molecular approach is presented for the rapid identification of pathogens combining PCR amplification with microarray detection. The DNA chip comprises oligonucleotide capture probes for 25 different pathogens including Gram positive cocci, the most frequently encountered genera of Enterobacteriaceae, non-fermenter and clinical relevant Candida species. The observed detection limits varied from 10 cells (e.g. E. coli) to 105 cells (S. aureus) per mL artificially spiked blood. Thus the current low sensitivity for some species still represents a barrier for clinical application. Successful discrimination of closely related species was achieved by a signal pattern recognition approach based on the k-nearest-neighbour method. A prototype software providing this statistical evaluation was developed, allowing correct identification in 100 % of the cases at the genus and in 96.7 % at the species level (n = 241). Conclusion The newly developed molecular assay can be carried out within 6 hours in a research laboratory from pathogen isolation to species identification. From our results we conclude that DNA microarrays can be a useful tool for rapid identification of closely related pathogens particularly when the protocols are adapted to the special clinical scenarios. PMID:17697354

  6. Low Level of Resistance in Enterococci Isolated in Four Hospitals, Marseille, France.

    PubMed

    Abat, Cédric; Raoult, Didier; Rolain, Jean-Marc

    2016-04-01

    Enterococci are gram-positive cocci responsible for various infections worldwide, and their prevalence of antibiotic resistance greatly varies worldwide. This study investigates the prevalence of resistance to antibiotics in enterococci from patients admitted in the four university hospitals of Marseille between January 2013 and September 2014. Two thousand nine hundred seventy-six patients-bacteria couples were identified (2,507 Enterococcus faecalis and 469 Enterococcus faecium) in the four university hospitals of Marseille. 1.3%, 8.9%, 1.4%, and 0% of E. faecalis strains were resistant to amoxicillin, gentamicin, teicoplanin, and vancomycin, respectively, and 83.9%, 49.2%, 1.3%, and 0.2% of E. faecium strains were resistant to amoxicillin, gentamicin, teicoplanin, and vancomycin, respectively. Resistance to aminoglycosides and vancomycin in strains isolated from blood cultures was significantly lower than that of most European countries included in the 2012 European Antimicrobial Resistance Surveillance Network report. Our low percentage of antibiotic resistance in enterococci is likely due to a low level of E. faecium infections, underlining the need to implement surveillance systems, especially to monitor the E. faecalis/E. faecium ratio evolution in blood cultures and others. PMID:26247097

  7. A thiol-disulfide oxidoreductase of the Gram-positive pathogen Corynebacterium diphtheriae is essential for viability, pilus assembly, toxin production and virulence

    PubMed Central

    Reardon-Robinson, Melissa E.; Osipiuk, Jerzy; Jooya, Neda; Chang, Chungyu; Joachimiak, Andrzej; Das, Asis; Ton-That, Hung

    2016-01-01

    Summary The Gram-positive pathogen Corynebacterium diphtheriae exports through the Sec apparatus many extracellular proteins that include the key virulence factors diphtheria toxin and the adhesive pili. How these proteins attain their native conformations after translocation as unfolded precursors remains elusive. The fact that the majority of these exported proteins contain multiple cysteine residues and that several membrane-bound oxidoreductases are encoded in the corynebacterial genome suggests the existence of an oxidative protein-folding pathway in this organism. Here we show that the shaft pilin SpaA harbors a disulfide bond in vivo and alanine substitution of these cysteines abrogates SpaA polymerization and leads to the secretion of degraded SpaA peptides. We then identified a thiol-disulfide oxidoreductase (MdbA), whose structure exhibits a conserved thioredoxin-like domain with a CPHC active site. Remarkably, deletion of mdbA results in a severe temperature-sensitive cell division phenotype. This mutant also fails to assemble pilus structures and is greatly defective in toxin production. Consistent with these defects, the ΔmdbA mutant is attenuated in a guinea pig model of diphtheritic toxemia. Given its diverse cellular functions in cell division, pilus assembly and toxin production, we propose that MdbA is a component of the general oxidative folding machine in C. diphtheriae. PMID:26294390

  8. A novel compound from the marine bacterium Bacillus pumilus S6-15 inhibits biofilm formation in gram-positive and gram-negative species.

    PubMed

    Nithya, Chari; Devi, Muthu Gokila; Karutha Pandian, Shunmugiah

    2011-05-01

    Biofilm formation is a critical problem in nosocomial infections and in the aquaculture industries and biofilms show high resistance to antibiotics. The aim of the present study was to reveal a novel anti-biofilm compound from marine bacteria against antibiotic resistant gram-positive and gram-negative biofilms. The bacterial extract (50 μg ml(-1)) of S6-01 (Bacillus indicus = MTCC 5559) showed 80-90% biofilm inhibition against Escherichia coli, Shigella flexneri, Proteus mirabilis and S6-15 (Bacillus pumilus = MTCC 5560) showed 80-95% biofilm inhibition against all the 10 tested organisms. Furthermore, they also reduced the hydrophobicity index and extracellular polymeric substances (EPS) production. Structural elucidation of the active principle in S6-15 using GC-MS, (1)H NMR, and (13)C NMR spectral data revealed it to be 4-phenylbutanoic acid. This is the first report of 4-phenylbutanoic acid as a natural product. The purified compound (10-15 μg ml(-1)) showed potential activity against a wide range of biofilms. This study for the first time, reports a novel anti-biofilm compound from a marine bacterium with wide application in medicine and the aquaculture industry. PMID:21614700

  9. A metal-repressed promoter from gram-positive Bacillus subtilis is highly active and metal-induced in gram-negative Cupriavidus metallidurans.

    PubMed

    Ribeiro-dos-Santos, Gabriela; Biondo, Ronaldo; Quadros, Oeber de Freitas; Vicente, Elisabete José; Schenberg, Ana Clara Guerrini

    2010-10-15

    A synthetic version of the metal-regulated gene A (mrgA) promoter from Bacillus subtilis, which in this Gram-positive bacterium is negatively regulated by manganese, iron, cobalt, or copper turned out to promote high level of basal gene expression that is further enhanced by Co(II), Cd(II), Mn(II), Zn(II), Cu(II), or Ni(II), when cloned in the Gram-negative bacterium Cupriavidus metallidurans. Promoter activity was monitored by expression of the reporter gene coding for the enhanced green fluorescent protein (EGFP), and cellular intensity fluorescence was quantified by flow cytometry. Expression levels in C. metallidurans driven by the heterologous promoter, here called pan, ranged from 20- to 53-fold the expression level driven by the Escherichia coli lac promoter (which is constitutively expressed in C. metallidurans), whether in the absence or presence of metal ions, respectively. The pan promoter did also function in E. coli in a constitutive pattern, regardless of the presence of Mn(II) or Fe(II). In conclusion, the pan promoter proved to be a powerful tool to express heterologous proteins in Gram-negative bacteria, especially in C. metallidurans grown upon high levels of toxic metals, with potential applications in bioremediation. PMID:20517979

  10. In vitro antimicrobial findings for fusidic acid tested against contemporary (2008-2009) gram-positive organisms collected in the United States.

    PubMed

    Jones, Ronald N; Mendes, Rodrigo E; Sader, Helio S; Castanheira, Mariana

    2011-06-01

    Fusidic acid has a long history of consistent activity against staphylococcal pathogens including methicillin-resistant Staphylococcus aureus (MRSA). Fusidic acid (CEM-102) was susceptibility tested against a surveillance study collection of 12,707 Gram-positive pathogens (2008-2009) from the United States. Reference broth microdilution method results demonstrated the following MIC(50/90) results: S. aureus (.12/.25 μg/mL), coagulase-negative staphylococci (.12/.25 μg/mL), enterococci (4/4 μg/mL), Streptococcus pyogenes (4/8 μg/mL), and viridans group Streptococcus spp. (>8/>8 μg/mL). At a proposed susceptible breakpoint (≤1 μg/mL), fusidic acid inhibited 99.7% of MRSA strains and 99.3% to 99.9% of multidrug-resistant phenotypes of S. aureus. Furthermore, S. aureus strains nonsusceptible to fusidic acid (.35%) generally had detectable resistance mechanisms (fusA, B, C, and E). Reviews of in vitro susceptibility test development confirm the accuracy and intermethod reproducibility of various fusidic acid methods. Fusidic acid is a promising oral therapy for staphylococcal skin and skin structure infections in the United States, where the contemporary S. aureus population remains without significant resistance. PMID:21546624

  11. Structural and functional conversion of molecular chaperone ClpB from the gram-positive halophilic lactic acid bacterium Tetragenococcus halophilus mediated by ATP and stress.

    PubMed

    Sugimoto, Shinya; Yoshida, Hiroyuki; Mizunoe, Yoshimitsu; Tsuruno, Keigo; Nakayama, Jiro; Sonomoto, Kenji

    2006-12-01

    In this study, we report the purification, initial structural characterization, and functional analysis of the molecular chaperone ClpB from the gram-positive, halophilic lactic acid bacterium Tetragenococcus halophilus. A recombinant T. halophilus ClpB (ClpB(Tha)) was overexpressed in Escherichia coli and purified by affinity chromatography, hydroxyapatite chromatography, and gel filtration chromatography. As demonstrated by gel filtration chromatography, chemical cross-linking with glutaraldehyde, and electron microscopy, ClpB(Tha) forms a homohexameric single-ring structure in the presence of ATP under nonstress conditions. However, under stress conditions, such as high-temperature (>45 degrees C) and high-salt concentrations (>1 M KCl), it dissociated into dimers and monomers, regardless of the presence of ATP. The hexameric ClpB(Tha) reactivated heat-aggregated proteins dependent upon the DnaK system from T. halophilus (KJE(Tha)) and ATP. Interestingly, the mixture of dimer and monomer ClpB(Tha), which was formed under stress conditions, protected substrate proteins from thermal inactivation and aggregation in a manner similar to those of general molecular chaperones. From these results, we hypothesize that ClpB(Tha) forms dimers and monomers to function as a holding chaperone under stress conditions, whereas it forms a hexamer ring to function as a disaggregating chaperone in cooperation with KJE(Tha) and ATP under poststress conditions. PMID:16997952

  12. Structural and Functional Conversion of Molecular Chaperone ClpB from the Gram-Positive Halophilic Lactic Acid Bacterium Tetragenococcus halophilus Mediated by ATP and Stress▿

    PubMed Central

    Sugimoto, Shinya; Yoshida, Hiroyuki; Mizunoe, Yoshimitsu; Tsuruno, Keigo; Nakayama, Jiro; Sonomoto, Kenji

    2006-01-01

    In this study, we report the purification, initial structural characterization, and functional analysis of the molecular chaperone ClpB from the gram-positive, halophilic lactic acid bacterium Tetragenococcus halophilus. A recombinant T. halophilus ClpB (ClpBTha) was overexpressed in Escherichia coli and purified by affinity chromatography, hydroxyapatite chromatography, and gel filtration chromatography. As demonstrated by gel filtration chromatography, chemical cross-linking with glutaraldehyde, and electron microscopy, ClpBTha forms a homohexameric single-ring structure in the presence of ATP under nonstress conditions. However, under stress conditions, such as high-temperature (>45°C) and high-salt concentrations (>1 M KCl), it dissociated into dimers and monomers, regardless of the presence of ATP. The hexameric ClpBTha reactivated heat-aggregated proteins dependent upon the DnaK system from T. halophilus (KJETha) and ATP. Interestingly, the mixture of dimer and monomer ClpBTha, which was formed under stress conditions, protected substrate proteins from thermal inactivation and aggregation in a manner similar to those of general molecular chaperones. From these results, we hypothesize that ClpBTha forms dimers and monomers to function as a holding chaperone under stress conditions, whereas it forms a hexamer ring to function as a disaggregating chaperone in cooperation with KJETha and ATP under poststress conditions. PMID:16997952

  13. Cell Shaving and False-Positive Control Strategies Coupled to Novel Statistical Tools to Profile Gram-Positive Bacterial Surface Proteomes.

    PubMed

    Solis, Nestor; Cordwell, Stuart J

    2016-01-01

    A powerful start to the discovery and design of novel vaccines, and for better understanding of host-pathogen interactions, is to profile bacterial surfaces using the proteolytic digestion of surface-exposed proteins under mild conditions. This "cell shaving" approach has the benefit of both identifying surface proteins and their surface-exposed epitopes, which are those most likely to interact with host cells and/or the immune system, providing a comprehensive overview of bacterial cell topography. An essential requirement for successful cell shaving is to account for (or minimize) cellular lysis that can occur during the shaving procedure and thus generate data that is biased towards non-surface (e.g., cytoplasmic) proteins. This is further complicated by the presence of "moonlighting" proteins, which are proteins predicted to be intracellular but with validated surface or extracellular functions. Here, we describe an optimized cell shaving protocol for Gram-positive bacteria that uses proteolytic digestion and a "false-positive" control to reduce the number of intracellular contaminants in these datasets. Released surface-exposed peptides are analyzed by liquid chromatography (LC) coupled to high-resolution tandem mass spectrometry (MS/MS). Additionally, the probabilities of proteins being surface exposed can be further calculated by applying novel statistical tools. PMID:27311663

  14. Growth of Ag-nanoparticles in an aqueous solution and their antimicrobial activities against Gram positive, Gram negative bacterial strains and Candida fungus.

    PubMed

    Aazam, Elham Shafik; Zaheer, Zoya

    2016-04-01

    Silver nanoparticles (AgNPs) were synthesized using Ocimum sanctum (Tulsi) leaves aqueous extract as reducing as well as a capping agent in absence and presence of cetyltrimethylammonium bromide (CTAB). The resulting nanomaterials were characterized by UV-visible spectrophotometer, and transmission electron microscope. The UV-Vis spectroscopy revealed the formation of AgNPs at 400-450 nm. TEM photographs indicate that the truncated triangular silver nanoplates and/or spherical morphology of the AgNPs with an average diameter of 25 nm have been distorted markedly in presence of CTAB. The AgNPs were almost mono disperse in nature. Antimicrobial activities of AgNPs were determined by using two bacteria (Gram positive Staphylococcus aureus MTCC-3160), Gram negative Escherichia coli MTCC-450) and one species of Candida fungus (Candida albicans ATCC 90030) with Kirby-Bauer or disc diffusion method. The zone of inhibition seems extremely good showing a relatively large zone of inhibition in both Staphylococcus aureus, Escherichia coli, and Candida albicans strains. PMID:26796584

  15. The Comparison of the Combined Toxicity between Gram-negative and Gram-positive Bacteria: a Case Study of Antibiotics and Quorum-sensing Inhibitors.

    PubMed

    Wang, Dali; Lin, Zhifen; Ding, Xiruo; Hu, Jingyun; Liu, Ying

    2016-02-01

    Quorum-sensing inhibitors (QSIs) are being used increasingly in diverse fields, and are likely to end up in the environment, where they may encounter the antibiotics and consequently cause joint effects on biological systems. However, the potential joint effects of QSIs and antibiotics have received little attention. In this study, the joint effects of antibiotics, represented by sulfonamides (SAs) and penicillin, as well as three potential QSIs, were investigated using both Gram-negative (Escherichia coli, E. coli) and Gram-positive bacteria (Bacillus subtilis, B. subtilis). It was found that E. coli tend to be more sensitive to the individual drugs than B. subtilis, whereas the joint effects on the two bacteria showed no difference regarding the same combination of antibiotics and QSIs. In general, SAs presented additive effects with γ-Valerolactone and 2-Pyrrolidinone, but antagonistic effects with L-(+)-Prolinol; penicillin exhibited antagonistic effects with all three QSIs. Moreover, it was found that the rate of resistance in E. coli against the individual antibiotics was reduced through the addition of the QSIs, which suggests a promising use of the QSIs in the bacterial infection treatment. This study also offers a valuable reference for the risk assessment of the antibiotics and QSIs in the real environment. PMID:27491790

  16. A thiol-disulfide oxidoreductase of the Gram-positive pathogen Corynebacterium diphtheriae is essential for viability, pilus assembly, toxin production and virulence.

    PubMed

    Reardon-Robinson, Melissa E; Osipiuk, Jerzy; Jooya, Neda; Chang, Chungyu; Joachimiak, Andrzej; Das, Asis; Ton-That, Hung

    2015-12-01

    The Gram-positive pathogen Corynebacterium diphtheriae exports through the Sec apparatus many extracellular proteins that include the key virulence factors diphtheria toxin and the adhesive pili. How these proteins attain their native conformations after translocation as unfolded precursors remains elusive. The fact that the majority of these exported proteins contain multiple cysteine residues and that several membrane-bound oxidoreductases are encoded in the corynebacterial genome suggests the existence of an oxidative protein-folding pathway in this organism. Here we show that the shaft pilin SpaA harbors a disulfide bond in vivo and alanine substitution of these cysteines abrogates SpaA polymerization and leads to the secretion of degraded SpaA peptides. We then identified a thiol-disulfide oxidoreductase (MdbA), whose structure exhibits a conserved thioredoxin-like domain with a CPHC active site. Remarkably, deletion of mdbA results in a severe temperature-sensitive cell division phenotype. This mutant also fails to assemble pilus structures and is greatly defective in toxin production. Consistent with these defects, the ΔmdbA mutant is attenuated in a guinea pig model of diphtheritic toxemia. Given its diverse cellular functions in cell division, pilus assembly and toxin production, we propose that MdbA is a component of the general oxidative folding machine in C. diphtheriae. PMID:26294390

  17. Sulfoxides, Analogues of L-Methionine and L-Cysteine As Pro-Drugs against Gram-Positive and Gram-Negative Bacteria.

    PubMed

    Anufrieva, N V; Morozova, E A; Kulikova, V V; Bazhulina, N P; Manukhov, I V; Degtev, D I; Gnuchikh, E Yu; Rodionov, A N; Zavilgelsky, G B; Demidkina, T V

    2015-01-01

    The problem of resistance to antibiotics requires the development of new classes of broad-spectrum antimicrobial drugs. The concept of pro-drugs allows researchers to look for new approaches to obtain effective drugs with improved pharmacokinetic and pharmacodynamic properties. Thiosulfinates, formed enzymatically from amino acid sulfoxides upon crushing cells of genus Allium plants, are known as antimicrobial compounds. The instability and high reactivity of thiosulfinates complicate their use as individual antimicrobial compounds. We propose a pharmacologically complementary pair: an amino acid sulfoxide pro-drug and vitamin B6 - dependent methionine γ-lyase, which metabolizes it in the patient's body. The enzyme catalyzes the γ- and β-elimination reactions of sulfoxides, analogues of L-methionine and L-cysteine, which leads to the formation of thiosulfinates. In the present work, we cloned the enzyme gene from Clostridium sporogenes. Ionic and tautomeric forms of the internal aldimine were determined by lognormal deconvolution of the holoenzyme spectrum and the catalytic parameters of the recombinant enzyme in the γ- and β-elimination reactions of amino acids, and some sulfoxides of amino acids were obtained. For the first time, the possibility of usage of the enzyme for effective conversion of sulfoxides was established and the antimicrobial activity of thiosulfinates against Gram-negative and Gram-positive bacteria in situ was shown. PMID:26798500

  18. Crystal Structure of DsbA from Corynebacterium diphtheriae and Its Functional Implications for CueP in Gram-Positive Bacteria

    PubMed Central

    Um, Si-Hyeon; Kim, Jin-Sik; Song, Saemee; Kim, Nam Ah; Jeong, Seong Hoon; Ha, Nam-Chul

    2015-01-01

    In Gram-negative bacteria in the periplasmic space, the dimeric thioredoxin-fold protein DsbC isomerizes and reduces incorrect disulfide bonds of unfolded proteins, while the monomeric thioredoxin-fold protein DsbA introduces disulfide bonds in folding proteins. In the Gram-negative bacteria Salmonella enterica serovar Typhimurium, the reduced form of CueP scavenges the production of hydroxyl radicals in the copper-mediated Fenton reaction, and DsbC is responsible for keeping CueP in the reduced, active form. Some DsbA proteins fulfill the functions of DsbCs, which are not present in Gram-positive bacteria. In this study, we identified a DsbA homologous protein (CdDsbA) in the Corynebacterium diphtheriae genome and determined its crystal structure in the reduced condition at 1.5 Å resolution. CdDsbA consists of a monomeric thioredoxin-like fold with an inserted helical domain and unique N-terminal extended region. We confirmed that CdDsbA has disulfide bond isomerase/reductase activity, and we present evidence that the N-terminal extended region is not required for this activity and folding of the core DsbA-like domain. Furthermore, we found that CdDsbA could reduce CueP from C. diphtheriae. PMID:26082031

  19. Sulfoxides, Analogues of L-Methionine and L-Cysteine As Pro-Drugs against Gram-Positive and Gram-Negative Bacteria

    PubMed Central

    Anufrieva, N. V.; Morozova, E. A.; Kulikova, V. V.; Bazhulina, N. P.; Manukhov, I. V.; Degtev, D. I.; Gnuchikh, E. Yu.; Rodionov, A. N.; Zavilgelsky, G. B.; Demidkina, T. V.

    2015-01-01

    The problem of resistance to antibiotics requires the development of new classes of broad-spectrum antimicrobial drugs. The concept of pro-drugs allows researchers to look for new approaches to obtain effective drugs with improved pharmacokinetic and pharmacodynamic properties. Thiosulfinates, formed enzymatically from amino acid sulfoxides upon crushing cells of genus Allium plants, are known as antimicrobial compounds. The instability and high reactivity of thiosulfinates complicate their use as individual antimicrobial compounds. We propose a pharmacologically complementary pair: an amino acid sulfoxide pro-drug and vitamin B6 – dependent methionine γ-lyase, which metabolizes it in the patient’s body. The enzyme catalyzes the γ- and β-elimination reactions of sulfoxides, analogues of L-methionine and L-cysteine, which leads to the formation of thiosulfinates. In the present work, we cloned the enzyme gene from Clostridium sporogenes. Ionic and tautomeric forms of the internal aldimine were determined by lognormal deconvolution of the holoenzyme spectrum and the catalytic parameters of the recombinant enzyme in the γ- and β-elimination reactions of amino acids, and some sulfoxides of amino acids were obtained. For the first time, the possibility of usage of the enzyme for effective conversion of sulfoxides was established and the antimicrobial activity of thiosulfinates against Gram-negative and Gram-positive bacteria in situ was shown. PMID:26798500

  20. Effect of kojic acid-grafted-chitosan oligosaccharides as a novel antibacterial agent on cell membrane of gram-positive and gram-negative bacteria.

    PubMed

    Liu, Xiaoli; Xia, Wenshui; Jiang, Qixing; Xu, Yanshun; Yu, Peipei

    2015-09-01

    Our work here, for the first time, reported the antibacterial activity of kojic acid-grafted-chitosan oligosaccharides (COS/KA) against three gram-positive and three gram-negative bacteria. Integrity of cell membrane, outer membrane (OM) and inner membrane (IM) permeabilization assay, alkaline phosphatase (ALP) and glucose-6-phosphate dehydrogenase (G6PDH) assay, and SDS-PAGE assay techniques were used to investigate the interactions between COS/KA and bacterial membranes. The antibacterial activity of COS/KA was higher than those of unmodified COS. The electric conductivity of bacteria suspensions increased, followed by increasing of the units of average release for ALP and G6PDH. COS/KA can also rapidly increase the 1-N-phenylanphthylamine (NPN) uptake and the release of β-galactosidase via increasing the permeability of OM and IM in Escherichia coli. SDS-PAGE indicated the content of cellular soluble proteins decreased significantly in COS/KA-treated bacteria. Hence, COS/KA has potential in food industry and biomedical sciences. PMID:25682520

  1. Intracerebral abscess with dissecting pneumocephalus caused by a gas-producing gram-positive rod following craniotomy for glioblastoma multiforme resection.

    PubMed

    Sarkiss, Christopher A; Soleymani, Teo; Caplan, Justin M; Dorsi, Michael J; Huang, Judy

    2013-11-01

    Propionibacterium acnes (P. acnes), an indolent and slow-growing anaerobic gram-positive bacterium, has largely been known as a commensal organism of the normal skin flora. However, P. acnes is increasingly being recognized as the causative infectious organism complicating craniotomies and shunt insertions. To our knowledge, we present the first reported patient with an intracerebral abscess with dissecting pneumocephalus caused by P. acnes. A 58-year-old woman who was immunocompetent presented 3 weeks after a craniotomy for resection of a glioblastoma multiforme with worsening mental status, lethargy and left hemiparesis. Head CT scans and MRI demonstrated significant vasogenic edema and dissecting pneumocephalus in the resection cavity. A craniotomy was performed and purulent material was found in the subdural space and resection cavity. Cultures were positive for P. acnes. She completed a full course of intravenous antibiotics appropriate for the organism. The infection was eradicated and the patient survived albeit with persistent deficits. This case illustrates the importance of considering an underlying intracerebral abscess in patients with worsening neurological function and pneumocephalus on imaging several weeks after surgery. Our review of the literature underscores the great importance in early recognition and treatment with both surgical debridement and antibiotic therapy in achieving optimal patient recovery. PMID:23688444

  2. In vitro susceptibilities of aerobic and facultative non-spore-forming gram-positive bacilli to HMR 3647 (RU 66647) and 14 other antimicrobials.

    PubMed

    Soriano, F; Fernández-Roblas, R; Calvo, R; García-Calvo, G

    1998-05-01

    The comparative in vitro activity of the ketolide HMR 3647 (RU 66647) and those of structurally related macrolide-lincosamide-streptogramin compounds (erythromycin, roxithromycin, azithromycin, clarithromycin, josamycin, lincomycin, pristinamycin, and quinupristin-dalfopristin) as well as those of benzylpenicillin, doxycycline, vancomycin, teicoplanin, levofloxacin, and rifapentine against 247 aerobic and facultative non-spore-forming gram-positive bacilli were determined by an agar dilution method. The ketolide was active against most organisms tested except Corynebacterium striatum, coryneform CDC group 12, and Oerskovia spp. The frequency of resistance to erythromycin and other macrolides as well as that to lincomycin was high. Pristinamycin and, to a lesser extent, quinupristin-dalfopristin were very active, but resistance to these agents was present in some strains of Rhodococcus equi, Listeria spp., C. striatum, Erysipelothrix rhusiopathiae, and Oerskovia spp. HMR 3647 was very active against all erythromycin-sensitive and many erythromycin-nonsusceptible strains, especially Corynebacterium minutissimum, Corynebacterium pseudodiphtheriticum, Corynebacterium amycolatum, and Corynebacterium jeikeium. In vitro resistance to benzylpenicillin was common, but doxycycline, vancomycin, and teicoplanin were very active against most organisms tested except E. rhusiopathiae, against which glycopeptide antibiotics were not active. The in vitro activity of levofloxacin was remarkable, but resistance to this agent was common for C. amycolatum, Corynebacterium urealyticum, C. jeikeium, and Oerskovia spp. strains. Rifapentine was also very active in vitro against many organisms, but resistance to this agent was always present in E. rhusiopathiae and was very common in C. striatum and C. urealyticum. PMID:9593121

  3. Effects of Photodynamic Therapy on Gram-Positive and Gram-Negative Bacterial Biofilms by Bioluminescence Imaging and Scanning Electron Microscopic Analysis

    PubMed Central

    Núñez, Silvia C.; Azambuja, Nilton; Fregnani, Eduardo R.; Rodriguez, Helena M.H.; Hamblin, Michael R.; Suzuki, Hideo; Ribeiro, Martha S.

    2013-01-01

    Abstract Objective: The aim of this study was to test photodynamic therapy (PDT) as an alternative approach to biofilm disruption on dental hard tissue, We evaluated the effect of methylene blue and a 660 nm diode laser on the viability and architecture of Gram-positive and Gram-negative bacterial biofilms. Materials and methods: Ten human teeth were inoculated with bioluminescent Pseudomonas aeruginosa or Enterococcus faecalis to form 3 day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify and evaluate the bacterial viability, and scanning electron microscopic (SEM) imaging was used to assess architecture and morphology of bacterial biofilm before and after PDT employing methylene blue and 40 mW, 660 nm diode laser light delivered into the root canal via a 300 μm fiber for 240 sec, resulting in a total energy of 9.6 J. The data were statistically analyzed with analysis of variance (ANOVA) followed by Tukey test. Results: The bacterial reduction showed a dose dependence; as the light energy increased, the bioluminescence decreased in both planktonic suspension and in biofilms. The SEM analysis showed a significant reduction of biofilm on the surface. PDT promoted disruption of the biofilm and the number of adherent bacteria was reduced. Conclusions: The photodynamic effect seems to disrupt the biofilm by acting both on bacterial cells and on the extracellular matrix. PMID:23822168

  4. The gills are an important site of iNOS expression in rainbow trout Oncorhynchus mykiss after challenge with the gram-positive pathogen Renibacterium salmoninarum.

    PubMed

    Campos-Perez, J J; Ward, M; Grabowski, P S; Ellis, A E; Secombes, C J

    2000-01-01

    Following injection challenge of rainbow trout with the Gram-positive pathogen Renibacterium salmoninarum, serum nitrate levels increased indicative of NO production. The timing and amount of nitrate produced varied with the virulence of the bacterial strain used, with the highest levels seen in fish challenged with the most virulent (autoaggregating) strain. Immunization with a killed R. salmoninarum preparation in Freund's incomplete adjuvant significantly increased nitrate levels after challenge. Inducible nitric oxide synthase (iNOS) transcript expression was detectable in rainbow trout tissues after injection challenge with R. salmoninarum, and its induction in the gills was both quick (between 3 and 6 hr) and relatively prolonged (lasting several days). iNOS expression in the kidney was also seen at a later stage (24 hr) but appeared to switch off relatively rapidly. Bath challenge with R. salmoninarum also induced iNOS expression in gill, and a variable expression in the gut and kidney also occurred. These results highlight the importance of the gills, not only as a point of entry of pathogens but also as a tissue capable of mounting an immune response. PMID:10651954

  5. Antimicrobial Activity of the Investigational Pleuromutilin Compound BC-3781 Tested against Gram-Positive Organisms Commonly Associated with Acute Bacterial Skin and Skin Structure Infections

    PubMed Central

    Biedenbach, Douglas J.; Paukner, Susanne; Ivezic-Schoenfeld, Zrinka; Jones, Ronald N.

    2012-01-01

    BC-3781 is a novel semisynthetic pleuromutilin antimicrobial agent developed as an intravenous and oral therapy for acute bacterial skin and skin structure infections (ABSSSI) and respiratory tract infections (RTI). BC-3781 and comparator agents were tested by the broth microdilution method against 1,893 clinical Gram-positive organisms predominantly causing ABSSSI. BC-3781 exhibited potent activity against methicillin-resistant Staphylococcus aureus (MIC50/90, 0.12/0.25 μg/ml), coagulase-negative staphylococci (MIC50/90, 0.06/0.12 μg/ml), β-hemolytic streptococci (MIC50/90, 0.03/0.06 μg/ml), viridans group streptococci (MIC50/90, 0.12/0.5 μg/ml), and Enterococcus faecium (including vancomycin-nonsusceptible strains) (MIC50/90, 0.12/2 μg/ml). Compared with other antibiotics in use for the treatment of ABSSSI, BC-3781 displayed the lowest MICs and only a minimal potential for cross-resistance with other antimicrobial classes. PMID:22232289

  6. Proteinase-producing halophilic lactic acid bacteria isolated from fish sauce fermentation and their ability to produce volatile compounds.

    PubMed

    Udomsil, Natteewan; Rodtong, Sureelak; Tanasupawat, Somboon; Yongsawatdigul, Jirawat

    2010-07-15

    Halophilic lactic acid bacteria were isolated from fish sauce mashes fermented at 1 to 12 months. Seven out of sixty-four isolates were selected according to their proteolytic activity and growth at 25% NaCl for characterization and investigation of volatile compound production. All selected isolates were Gram-positive cocci with pairs/tetrads and grew at 0-25% NaCl, pH 4.5-9.0. Results of 16S rRNA gene sequence analysis showed 99% homology to Tetragenococcus halophilus ATCC 33315. The restriction fragment length polymorphism (RFLP) patterns of all isolates were also similar to those of T. halophilus ATCC 33315. These isolates were, thus, identified as T. halophilus. All isolates hydrolyzed fish protein in the medium containing 25% NaCl. Intracellular aminopeptidase of 7 isolates exhibited the highest activity of 2.85-3.67 U/ml toward Ala-p-nitroanilide (Ala-pNA). T.halophilus strains MS33 and M11 showed the highest alanyl aminopeptidase activity (P<0.05), and produced histamine in mGYP broth containing 5 and 25% NaCl in the level of 6.62-22.55 and 13.14-20.39 mg/100ml, respectively. Predominant volatile compounds of fish broth containing 25% NaCl inoculated with T. halophilus MS33 and MRC5-5-2 were 1-propanol, 2-methylpropanal, and benzaldehyde, corresponding to major volatile compounds in fish sauce. T.halophilus appeared to play an important role in volatile compound formation during fish sauce fermentation. PMID:20541276

  7. Acyl Carrier Protein Synthases from Gram-Negative, Gram-Positive, and Atypical Bacterial Species: Biochemical and Structural Properties and Physiological Implications

    PubMed Central

    McAllister, Kelly A.; Peery, Robert B.; Zhao, Genshi

    2006-01-01

    Acyl carrier protein (ACP) synthase (AcpS) catalyzes the transfer of the 4′-phosphopantetheine moiety from coenzyme A (CoA) onto a serine residue of apo-ACP, resulting in the conversion of apo-ACP to the functional holo-ACP. The holo form of bacterial ACP plays an essential role in mediating the transfer of acyl fatty acid intermediates during the biosynthesis of fatty acids and phospholipids. AcpS is therefore an attractive target for therapeutic intervention. In this study, we have purified and characterized the AcpS enzymes from Escherichia coli, Streptococcus pneumoniae, and Mycoplasma pneumoniae, which exemplify gram-negative, gram-positive, and atypical bacteria, respectively. Our gel filtration column chromatography and cross-linking studies demonstrate that the AcpS enzyme from M. pneumoniae, like E. coli enzyme, exhibits a homodimeric structure, but the enzyme from S. pneumoniae exhibits a trimeric structure. Our biochemical studies show that the AcpS enzymes from M. pneumoniae and S. pneumoniae can utilize both short- and long-chain acyl CoA derivatives but prefer long-chain CoA derivatives as substrates. On the other hand, the AcpS enzyme from E. coli can utilize short-chain CoA derivatives but not the long-chain CoA derivatives tested. Finally, our biochemical studies show that M. pneumoniae AcpS is kinetically a very sluggish enzyme compared with those from E. coli and S. pneumoniae. Together, the results of these studies show that the AcpS enzymes from different bacterial species exhibit different native structures and substrate specificities with regard to the utilization of CoA and its derivatives. These findings suggest that AcpS from different microorganisms plays a different role in cellular physiology. PMID:16788183

  8. Effective photoinactivation of Gram-positive and Gram-negative bacterial strains using an HIV-1 Tat peptide-porphyrin conjugate.

    PubMed

    Bourré, Ludovic; Giuntini, Francesca; Eggleston, Ian M; Mosse, Charles A; Macrobert, Alexander J; Wilson, Michael

    2010-12-01

    Given that cell-penetrating peptides (CPP) are cationic and often amphipathic, similar to membrane-active antimicrobial peptides, it may be possible to use CPP conjugation to improve the delivery of photosensitisers for antimicrobial photodynamic therapy (antimicrobial PDT). We investigated the possibility of using a Tat peptide to deliver the photosensitiser, tetrakis(phenyl)porphyrin (TPP) and kill bacteria. The Tat peptide is a positively-charged mammalian cell-penetrating peptide with potent antimicrobial activity but no haemolytic activity. Fluorescence spectroscopy revealed that the bioconjugate can bind to and/or be incorporated into all bacterial species tested. All species were susceptible to the Tat-porphyrin, with the bactericidal effect being dependent on both the concentration and the light dose. Using the highest light dose, treatment with the Tat-porphyrin achieved reductions of 6.6 log(10) and 6.37 log(10) in the viable counts of Staphylococcus aureus and Streptococcus pyogenes, and reductions of 5.74 log(10) and 6.6 log(10) in the viable counts of Pseudomonas aeruginosa and Escherichia coli. Moreover, the Tat moiety appears to confer antimicrobial properties to the conjugate, particularly for the Gram positive strains, based on the observation of dark toxicity using 1 μM of Tat-porphyrin. Finally, the conjugate induced membrane destabilization by synergistic action of the peptide and PDT, resulting in carboxyfluorescein leakage from bacterial membrane-mimicking liposomes. These findings demonstrate that the use of CPP to deliver a photosensitiser is an effective way of improving the uptake and the treatment efficacy of antimicrobial PDT. PMID:20931134

  9. A new approach to treatment of resistant gram-positive infections: potential impact of targeted IV to oral switch on length of stay

    PubMed Central

    Desai, Mohammed; Franklin, Bryony Dean; Holmes, Alison H; Trust, Sarah; Richards, Mike; Jacklin, Ann; Bamford, Kathleen B

    2006-01-01

    Background Patients prescribed intravenous (IV) glycopeptides usually remain in hospital until completion of this treatment. Some of these patients could be discharged earlier if a switch to an oral antibiotic was made. This study was designed to identify the percentage of inpatients currently prescribed IV glycopeptides who could be discharged earlier if a switch to an oral agent was used, and to estimate the number of bed days that could be saved. We also aimed to identify the patient group(s) most likely to benefit, and to estimate the number of days of IV therapy that could be prevented in patients who remained in hospital. Methods Patients were included if they were prescribed an IV glycopeptide for 5 days or more. Predetermined IV to oral antibiotic switch criteria and discharge criteria were applied. A multiple logistic regression model was used to identify the characteristics of the patients most likely to be suitable for earlier discharge. Results Of 211 patients, 62 (29%) could have had a reduced length of stay if they were treated with a suitable oral antibiotic. This would have saved a total of 649 inpatient days (median 5 per patient; range 1–54). A further 31 patients (15%) could have switched to oral therapy as an inpatient thus avoiding IV line use. The patients most likely to be suitable for early discharge were those with skin and soft tissue infection, under the cardiology, cardiothoracic surgery, orthopaedics, general medical, plastic surgery and vascular specialities, with no high risk comorbidity and less than five other regularly prescribed drugs. Conclusion The need for glycopeptide therapy has a significant impact on length of stay. Effective targeting of oral antimicrobials could reduce the need for IV access, allow outpatient treatment and thus reduce the length of stay in patients with infections caused by antibiotic resistant gram-positive bacteria. PMID:16762061

  10. The Bacteroides mobilizable transposon Tn4555 integrates by a site-specific recombination mechanism similar to that of the gram-positive bacterial element Tn916.

    PubMed Central

    Tribble, G D; Parker, A C; Smith, C J

    1997-01-01

    The Bacteroides mobilizable transposon Tn4555 is a 12.2-kb molecule that encodes resistance to cefoxitin. Conjugal transposition is hypothesized to occur via a circular intermediate and is stimulated by coresident tetracycline resistance elements and low levels of tetracycline. In this work, the ends of the transposon were identified and found to consist of 12-bp imperfect inverted repeats, with an extra base at one end. In the circular form, the ends were separated by a 6-bp "coupling sequence" which was associated with either the left or the right transposon terminus when the transposon was inserted into the chromosome. Tn4555 does not duplicate its target site upon insertion. Using a conjugation-based transposition assay, we showed that the coupling sequence originated from 6 bases of genomic DNA flanking either side of the transposon prior to excision. Tn4555 preferentially transposed into a 589-bp genomic locus containing a 207-bp direct repeat. Integration occurred before or after the repeated sequence, with one integration site between the two repeats. These observations are consistent with a transposition model based on site-specific recombination. In the bacteriophage lambda model for site-specific recombination, the bacteriophage recombines with the Escherichia coli chromosome via a 7-bp "crossover" region. We propose that the coupling sequence of Tn4555 is analogous in function to the crossover region of lambda but that unlike the situation in lambda, recombination occurs between regions of nonhomologous DNA. This ability to recombine into divergent target sites is also a feature of the gram-positive bacterial transposon Tn916. PMID:9098073

  11. Silver nanocrystallites: Facile biofabrication using Shewanella oneidensis, and an evaluation of their comparative toxicity on Gram-negative and Gram-positive bacteria

    SciTech Connect

    Suresh, Anil K; Wang, Wei; Pelletier, Dale A; Moon, Ji Won; Gu, Baohua; Mortensen, Ninell P; Allison, David P; Joy, David Charles; Phelps, Tommy Joe; Doktycz, Mitchel John

    2010-01-01

    Microorganisms have long been known to develop resistance to metal ions either by sequestering metals inside the cell or by effluxing them into the extracellular media. Here we report the biosynthesis of extracellular silver based single nanocrystallites of well-defined composition and homogeneous morphology utilizing the -proteobacterium, Shewanella oneidensis strain MR-1, upon incubation with an aqueous solution of silver nitrate. Further characterization of these particles revealed that the crystals consist of small, reasonably monodispersed spheres in the size range 2 11 nm (with an average of 4 1.5 nm). The bactericidal effect of these biologically synthesized silver nanoparticles (biogenic-Ag) are compared to similar chemically synthesized nanoparticles (colloidal silver [colloidal-Ag] and oleate capped silver [oleate-Ag]). The determination of the bactericidal effect of these different silver nanoparticles was assessed using both Gram-negative (E. coli) and Gram-positive (B. subtilis) bacteria and based on the diameter of the inhibition zone in disc diffusion tests, minimum inhibitory concentrations, Live/Dead staining assays, and atomic force microscopy. From a toxicity perspective, a clear synthesis procedure, and a surface coat- and strain-dependent inhibition were observed for silver nanoparticles. Biogenic-Ag was found to be of higher toxicity when compared to colloidal-Ag for both E. coli and B. subtilis. E. coli was found to be more resistant to either of these nanoparticles than B. subtilis. In contrast, Oleate-Ag was not toxic to either of the bacteria. These findings have important implications for the potential uses of Ag nanomaterials and for their fate in biological and environmental systems.

  12. Regulation of the Alkane Hydroxylase CYP153 Gene in a Gram-Positive Alkane-Degrading Bacterium, Dietzia sp. Strain DQ12-45-1b

    PubMed Central

    Liang, Jie-Liang; JiangYang, Jing-Hong

    2015-01-01

    CYP153, one of the most common medium-chain n-alkane hydroxylases belonging to the cytochrome P450 superfamily, is widely expressed in n-alkane-degrading bacteria. CYP153 is also thought to cooperate with AlkB in degrading various n-alkanes. However, the mechanisms regulating the expression of the protein remain largely unknown. In this paper, we studied CYP153 gene transcription regulation by the potential AraC family regulator (CypR) located upstream of the CYP153 gene cluster in a broad-spectrum n-alkane-degrading Gram-positive bacterium, Dietzia sp. strain DQ12-45-1b. We first identified the transcriptional start site and the promoter of the CYP153 gene cluster. Sequence alignment of upstream regions of CYP153 gene clusters revealed high conservation in the −10 and −35 regions in Actinobacteria. Further analysis of the β-galactosidase activity in the CYP153 gene promoter-lacZ fusion cell indicated that the CYP153 gene promoter was induced by n-alkanes comprised of 8 to 14 carbon atoms, but not by derived decanol and decanic acid. Moreover, we constructed a cypR mutant strain and found that the CYP153 gene promoter activities and CYP153 gene transcriptional levels in the mutant strain were depressed compared with those in the wild-type strain in the presence of n-alkanes, suggesting that CypR served as an activator for the CYP153 gene promoter. By comparing CYP153 gene arrangements in Actinobacteria and Proteobacteria, we found that the AraC family regulator is ubiquitously located upstream of the CYP153 gene, suggesting its universal regulatory role in CYP153 gene transcription. We further hypothesize that the observed mode of CYP153 gene regulation is shared by many Actinobacteria. PMID:26567302

  13. Transcriptome-Wide Analyses of 5′-Ends in RNase J Mutants of a Gram-Positive Pathogen Reveal a Role in RNA Maturation, Regulation and Degradation

    PubMed Central

    Linder, Patrick; Lemeille, Sylvain; Redder, Peter

    2014-01-01

    RNA decay and maturation have in recent years been recognised as major regulatory mechanisms in bacteria. In contrast to Escherichia coli, the Firmicute (Gram-positive) bacteria often do not encode the well-studied endonuclease RNase E, but instead rely on the endonucleases RNase Y, RNase J1 and RNase J2, of which the latter two have additionally been shown to have 5′ to 3′ exonucleolytic activity. We have previously demonstrated that these RNases could be deleted individually in the pathogenic Firmicute Staphylococcus aureus; however, we here present that, outside a narrow permissive window of growth conditions, deleting one or both of the RNase J genes presents serious difficulties for the cell. Moreover, an active site mutant of RNase J1 behaved like a deletion, whereas no phenotypes were detected for the RNase J2 active site mutant. Furthermore, in order to study the in vivo enzymatic activity of RNase J1 and J2, a method was developed to map the exact 5′-ends of mature and processed RNA, on a global scale. An enrichment of 5′ RNA ends could be seen in the RNase J mutants, suggesting that their exonucleolytic activity is crucial for normal degradation of bulk RNA. Using the data to examine specific RNAs, we demonstrated that RNase J activity is needed for correct 5′ maturation of both the 16S rRNA and the RNase P ribozyme, and can also inactivate the latter, possibly as quality control. Additional examples show that RNase J perform initial cleavages, apparently competing with ribosomes for access to mRNAs. The novel 5′ mapping assay offers an exceptionally detailed view of RNase activity, and reveals that the roles of RNase J proteins are diverse, ranging from maturation and post-transcriptional regulation to degradation. PMID:24586213

  14. Structural Basis for the De-N-acetylation of Poly-β-1,6-N-acetyl-d-glucosamine in Gram-positive Bacteria*

    PubMed Central

    Little, Dustin J.; Bamford, Natalie C.; Pokrovskaya, Varvara; Robinson, Howard; Nitz, Mark; Howell, P. Lynne

    2014-01-01

    Exopolysaccharides are required for the development and integrity of biofilms produced by a wide variety of bacteria. In staphylococci, partial de-N-acetylation of the exopolysaccharide poly-β-1,6-N-acetyl-d-glucosamine (PNAG) by the extracellular protein IcaB is required for biofilm formation. To understand the molecular basis for PNAG de-N-acetylation, the structure of IcaB from Ammonifex degensii (IcaBAd) has been determined to 1.7 Å resolution. The structure of IcaBAd reveals a (β/α)7 barrel common to the family four carbohydrate esterases (CE4s) with the canonical motifs circularly permuted. The metal dependence of IcaBAd is similar to most CE4s showing the maximum rates of de-N-acetylation with Ni2+, Co2+, and Zn2+. From docking studies with β-1,6-GlcNAc oligomers and structural comparison to PgaB from Escherichia coli, the Gram-negative homologue of IcaB, we identify Arg-45, Tyr-67, and Trp-180 as key residues for PNAG binding during catalysis. The absence of these residues in PgaB provides a rationale for the requirement of a C-terminal domain for efficient deacetylation of PNAG in Gram-negative species. Mutational analysis of conserved active site residues suggests that IcaB uses an altered catalytic mechanism in comparison to other characterized CE4 members. Furthermore, we identified a conserved surface-exposed hydrophobic loop found only in Gram-positive homologues of IcaB. Our data suggest that this loop is required for membrane association and likely anchors IcaB to the membrane during polysaccharide biosynthesis. The work presented herein will help guide the design of IcaB inhibitors to combat biofilm formation by staphylococci. PMID:25359777

  15. Anaerococcus rubiinfantis sp. nov., isolated from the gut microbiota of a Senegalese infant with severe acute malnutrition.

    PubMed

    Tidjani Alou, Maryam; Khelaifia, Saber; Michelle, Caroline; Andrieu, Claudia; Armstrong, Nicholas; Bittar, Fadi; Sokhna, Cheikh; Diallo, Aldiouma; Fournier, Pierre-Edouard; Raoult, Didier; Million, Matthieu

    2016-08-01

    Anaerococcus rubiinfantis sp. nov. strain mt16(T) is a new species within the genus Anaerococcus, which was isolated by the culturomics approach from the gut microbiota of an infant suffering from kwashiorkor. A phenotypic, biochemical and proteomic description of this strain is hereby presented alongside a complete annotation of its genome. This strictly anaerobic species forms Gram-positive non-sporeforming cocci. The major fatty acid was hexadecanoic acid. The phylogenetic analysis of strain mt16(T) showed a 97.9% similarity level with Anaerococcus vaginalis, the closest validly published species. Its genome is 1,929,161 bp long with 29.5% G + C content and contains 1808 protein-coding genes and 56 RNA genes, among which are six rRNA genes. Genomic analysis identified 41/1864 coding genes as ORFans (2.2%) and at least 620/1808 (34.9%) orthologous proteins which are not shared with the closest phylogenetic species. We believe that the extension of the human anaerobic gut compendium by culturomics is one of the first steps that will improve the understanding of the links between the microbiome and health or disease. PMID:27328611

  16. Tamlicoccus marinus gen. nov., sp. nov., isolated from seawater.

    PubMed

    Lee, Soon Dong

    2013-06-01

    A novel actinobacterial strain was isolated from a seawater sample collected on Mara Island, Jeju, Republic of Korea. Cells of this organism were aerobic, Gram-positive, non-spore-forming, non-motile cocci that occurred singly or in pairs. Colonies were circular, smooth, convex and white-cream in colour. Phylogenetic analyses based on 16S rRNA gene sequences showed that the organism belonged to the family Dermacoccaceae and formed a monophyletic clade between the type strains of Demetria terragena (96.8% similarity) and Branchiibius hedensis (95.2% similarity). The cell-wall peptidoglycan contained L-lysine, alanine, aspartic acid, glutamic acid, glycine and serine, indicating that the isolate possessed peptidoglycan type A4α. The whole-cell sugars were galactose, glucose, mannose, xylose, arabinose, ribose and rhamnose. The major menaquinone was MK-8(H4). The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, an unknown phospholipid and five unknown lipids. The cellular fatty acid profile was represented by large amounts of iso-methyl branched and monounsaturated iso- and anteiso-methyl branched acids, along with the presence of a diagnostic 10-methyl acid. The G+C content of the DNA was 71 mol%. On the basis of data from polyphasic analyses presented here, strain MSW-24(T) is considered to represent a novel species of a new genus in the family Dermacoccaceae, for which the name Tamlicoccus marinus gen. nov., sp. nov. is proposed. The type strain of Tamlicoccus marinus is MSW-24(T) (=KCTC 19485(T)=DSM 21415(T)). PMID:23041643

  17. Microbial evolution of traditional mountain cheese and characterization of early fermentation cocci for selection of autochtonous dairy starter strains.

    PubMed

    Carafa, Ilaria; Clementi, Francesca; Tuohy, Kieran; Franciosi, Elena

    2016-02-01

    The microbial population of Traditional Mountain (TM) cheese was investigated and characterized for the selection of cocci suitable for developing new starter cultures. Samples of milk, curd and cheese at different ripening times were enumerated in selective culture media and 640 colonies were isolated from curd and cheese after 24 h of ripening. The Lactic Acid Bacteria (LAB) isolated from M17 were clustered into 231 biotypes by RAPD-PCR analysis and identified as Lactococcus lactis, Streptococcus thermophilus and Enterococcus faecalis. Forty percent of enterococci showed the in vitro ability to inhibit raw milk resident coliforms, but they were excluded as possible starters due to the presence of associated risk factors. All lactococci and streptococci were tested for their technological properties; 4 Lc. lactis subsp. lactis and 2 Sc. thermophilus which were fast acidifiers and did not produce unpleasant flavours were subjected to the freeze-drying stability test. Lc. lactis subsp. lactis biotype 68 and Sc. thermophilus biotype 93 showed the best technological properties and may be appropriate for cheese production. This work gave evidence of the high biodiversity of TM-cheese autochthonous biotypes which could be used as starter cultures for the improvement of TM-cheese technology. PMID:26678135

  18. Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria

    PubMed Central

    Mehmood, Shahid; Rehman, Malik A; Ismail, Hammad; Mirza, Bushra; Bhatti, Arshad S

    2015-01-01

    In this work, we highlighted the effect of surface modifications of one-dimensional (1D) ZnO nanostructures (NSs) grown by the vapor–solid mechanism on their antibacterial activity. Two sets of ZnO NSs were modified separately – one set was modified by annealing in an Ar environment, and the second set was modified in O2 plasma. Annealing in Ar below 800°C resulted in a compressed lattice, which was due to removal of Zn interstitials and increased O vacancies. Annealing above 1,000°C caused the formation of a new prominent phase, Zn2SiO4. Plasma oxidation of the ZnO NSs caused an expansion in the lattice due to the removal of O vacancies and incorporation of excess O. Photoluminescence (PL) spectroscopy was employed for the quantification of defects associated with Zn and O in the as-grown and processed ZnO NS. Two distinct bands were observed, one in the ultraviolet (UV) region, due to interband transitions, and other in the visible region, due to defects associated with Zn and O. PL confirmed the surface modification of ZnO NS, as substantial decrease in intensities of visible band was observed. Antibacterial activity of the modified ZnO NSs demonstrated that the surface modifications by Ar annealing limited the antibacterial characteristics of ZnO NS against Staphylococcus aureus. However, ZnO NSs annealed at 1,000°C or higher showed a remarkable antibacterial activity against Escherichia coli. O2 plasma–treated NS showed appreciable antibacterial activity against both E. coli and S. aureus. The minimum inhibition concentration was determined to be 0.5 mg/mL and 1 mg/mL for Ar-annealed and plasma-oxidized ZnO NS, respectively. It was thus proved that the O content at the surface of the ZnO NS was crucial to tune the antibacterial activity against both selected gram-negative (E. coli) and gram-positive (S. aureus) bacterial species. PMID:26213466

  19. Characteristics of lactic acid bacteria isolates and their effect on silage fermentation of fruit residues.

    PubMed

    Yang, Jinsong; Tan, Haisheng; Cai, Yimin

    2016-07-01

    The natural lactic acid bacteria (LAB) population, chemical composition, and silage fermentation of fruit residues were studied. Eighty-two strains of LAB were isolated from fruit residues such as banana leaf and stem, pineapple peel, and papaya peel. All strains were gram-positive and catalase-negative bacteria, and they were divided into 7 groups (A-G) according to morphological and biochemical characters. Strains in groups A to F were rods, and group G was cocci. Group F produced gas from glucose; other groups did not. Groups A to C and F formed dl-lactic acid, whereas groups D, E, and G formed l-lactic acid. Based on the 16S rRNA gene sequence and DNA-DNA hybridization analysis, groups A to G strains were identified as Lactobacillus plantarum (54.9% of the total isolates), Lactobacillus paraplantarum (3.6%), Lactobacillus nagelii (8.5%), Lactobacillus perolens (4.9%), Lactobacillus casei (11.0%), Lactobacillus fermentum (9.8%), and Enterococcus gallinarum (7.3%), respectively. Lactobacillus plantarum and Lactobacillus casei are the most frequently isolated from fruit residues as a dominant species, and they could grow at a lower pH conditions and produce more lactic acid than other isolates. Pineapple and papaya peels contained higher crude protein (11.5-13.8%) and water-soluble carbohydrate (16.8-22.4%), but lower acid detergent fiber contents (21.2 to 26.4%) than banana stems and leaves (8.2% crude protein, 42.8% acid detergent fiber, and 5.1% water-soluble carbohydrate). Compared with banana stem and leaf silages, the pineapple and papaya peel silages were well preserved with a lower pH and higher lactate content. The study suggests that the fruit residues contain excellent LAB species and abundant feed nutrients, and that they can be preserved as silage to be potential food resources for livestock. PMID:27108171

  20. Streptococcus hongkongensis sp. nov., isolated from a patient with an infected puncture wound and from a marine flatfish.

    PubMed

    Lau, Susanna K P; Curreem, Shirly O T; Lin, Cherry C N; Fung, Ami M Y; Yuen, Kwok-Yung; Woo, Patrick C Y

    2013-07-01

    A bacterium, HKU30(T), was isolated from the infected tissue of a patient with wound infection after puncture by a fish fin. Cells are facultative anaerobic, non-spore-forming, non-motile, Gram-positive cocci arranged in chains. Colonies were non-haemolytic. The strain was catalase, oxidase, urease and Voges-Proskauer test negative. It reacted with Lancefield's group G antisera and was resistant to optochin. It grew on bile aesculin agar and in 5 % NaCl. It was unidentified by three commercial identification systems. 16S rRNA gene sequence analysis indicated that the bacterium shared 98.2, 97.7, 97.4 and 97.1 % nucleotide identities with Streptococcus iniae, Streptococcus pseudoporcinus, Streptococcus parauberis and Streptococcus uberis, respectively. The DNA G+C content was 35.6 ± 0.9 mol% (mean ± sd). In view of the occupational exposure of the patient, an epidemiological study was performed to isolate the bacterium from marine fish. Two strains, with similar phenotypic and genotypic characteristics to those of HKU30(T), were isolated from a three-lined tongue sole (Cynoglossus abbreviatus) and an olive flounder (Paralichthys olivaceus) respectively. Phylogenetic analysis of four additional housekeeping genes, groEL, gyrB, sodA and rpoB, showed that the three isolates formed a distinct branch among known species of the genus Streptococcus, being most closely related to S. parauberis (CCUG 39954(T)). DNA-DNA hybridization demonstrated ≤ 53.8 % DNA relatedness between the three isolates and related species of the genus Streptococcus. A novel species, Streptococcus hongkongensis sp. nov., is proposed. The type strain is HKU30(T) ( = DSM 26014(T) = CECT 8154(T)). PMID:23264498

  1. Pneumococcal meningitis is promoted by single cocci expressing pilus adhesin RrgA.

    PubMed

    Iovino, Federico; Hammarlöf, Disa L; Garriss, Genevieve; Brovall, Sarah; Nannapaneni, Priyanka; Henriques-Normark, Birgitta

    2016-08-01

    Streptococcus pneumoniae (pneumococcus) is the primary cause of bacterial meningitis. Pneumococcal bacteria penetrates the blood-brain barrier (BBB), but the bacterial factors that enable this process are not known. Here, we determined that expression of pneumococcal pilus-1, which includes the pilus adhesin RrgA, promotes bacterial penetration through the BBB in a mouse model. S. pneumoniae that colonized the respiratory epithelium and grew in the bloodstream were chains of variable lengths; however, the pneumococci that entered the brain were division-competent, spherical, single cocci that expressed adhesive RrgA-containing pili. The cell division protein DivIVA, which is required for an ovoid shape, was localized at the poles and septum of pneumococcal chains of ovoid, nonseparated bacteria, but was absent in spherical, single cocci. In the bloodstream, a small percentage of pneumococci appeared as piliated, RrgA-expressing, DivIVA-negative single cocci, suggesting that only a minority of S. pneumoniae are poised to cross the BBB. Together, our data indicate that small bacterial cell size, which is signified by the absence of DivIVA, and the presence of an adhesive RrgA-containing pilus-1 mediate pneumococcal passage from the bloodstream through the BBB into the brain to cause lethal meningitis. PMID:27348589

  2. Antimicrobial susceptibility of clinically isolated anaerobic bacteria in a University Hospital Centre Split, Croatia in 2013.

    PubMed

    Novak, Anita; Rubic, Zana; Dogas, Varja; Goic-Barisic, Ivana; Radic, Marina; Tonkic, Marija

    2015-02-01

    Anaerobic bacteria play a significant role in many endogenous polymicrobial infections. Since antimicrobial resistance among anaerobes has increased worldwide, it is useful to provide local susceptibility data to guide empirical therapy. The present study reports recent data on the susceptibility of clinically relevant anaerobes in a University Hospital Centre (UHC) Split, Croatia. A total of 63 Gram-negative and 59 Gram-positive anaerobic clinical isolates from various body sites were consecutively collected from January to December 2013. Antimicrobial susceptibility testing was performed using standardized methods and interpreted using EUCAST criteria. Patient's clinical and demographic data were recorded by clinical microbiologist. Among 35 isolates of Bacteroides spp., 97.1% were resistant to penicillin (PCN), 5.7% to amoxicillin/clavulanic acid (AMC), 8.6% to piperacillin/tazobactam (TZP), 29.0% to clindamycin (CLI) and 2.9% to metronidazole (MZ). Percentages of susceptible strains to imipenem (IPM), meropenem (MEM) and ertapenem (ETP) were 94.3. Resistance of other Gram-negative bacilli was 76.0% to PCN, 8.0% to AMC, 12.0% to TZP, 28.0% to CLI and 8% to MZ. All other Gram-negative strains were fully susceptible to MEM and ETP, while 96.0% were susceptible to IPM. Clostridium spp. isolates were 100% susceptible to all tested antibiotics except to CLI (two of four tested isolates were resistant). Propionibacterium spp. showed resistance to CLI in 4.3%, while 100% were resistant to MZ. Among other Gram-positive bacilli, 18.2% were resistant to PCN, 9.1% to CLI and 54.5% to MZ, while 81.8% of isolates were susceptible to carbapenems. Gram-positive cocci were 100% susceptible to all tested antimicrobials except to MZ, where 28.6% of resistant strains were recorded. Abdomen was the most common source of isolates (82.5%). The most prevalent types of infection were abscess (22.1%), sepsis (14.8%), appendicitis (13.9%) and peritonitis (6.6%). Twenty four patients (19

  3. Ornithinimicrobium pekingense sp. nov., isolated from activated sludge.

    PubMed

    Liu, Xing-Yu; Wang, Bao-Jun; Jiang, Cheng-Ying; Liu, Shuang-Jiang

    2008-01-01

    The bacterial strain LW6(T) was isolated from activated sludge of a wastewater treatment bioreactor. Cells of strain LW6(T) are Gram-positive, irregular, short rods and cocci, 0.5-0.8x1.0-1.6 microm. Colonies are light-yellow, smooth, circular and 0.2-1.0 mm in diameter after 3 days incubation. Strain LW6(T) is aerobic and heterotrophic. It grows at a temperature range of 26-38 degrees C and pH range of 6-9, with optimal growth at 33-37 degrees C and pH 7.8-8.2. The predominant cellular fatty acids of strain LW6(T) are iso-C(15:0) (38.9%) and iso-C(17:1)omega9c (18.8%). Strain LW6(T) has the major respiratory menaquinones MK-8(H(4)) and MK-8(H(2)) and polar lipids phosphatidylinositol, phosphatidylglycerol, diphosphatidylglycerol and unknown glycolipid/phospholipids. The cell wall peptidoglycan of strain LW6(T) contained the amino acids ornithine, lysine, glutamic acid, alanine, glycine and aspartic acid. Its molar DNA G+C content is 69 mol% (T(m)). Analysis of 16S rRNA gene sequences indicated that strain LW6(T) was related phylogenetically to members of the genus Ornithinimicrobium, with similarities ranging from 98.3 to 98.7%. The DNA-DNA relatedness of strain LW6(T) to Ornithinimicrobium humiphilum DSM 12362(T) and Ornithinimicrobium kibberense K22-20(T) was respectively 31.5 and 15.2%. Based on these results, it is concluded that strain LW6(T) represents a novel species of the genus Ornithinimicrobium, for which the name Ornithinimicrobium pekingense sp. nov. is proposed. The type strain is strain LW6(T) (=CGMCC 1.5362(T) =JCM 14001(T)). PMID:18175694

  4. Isolation and characterization of thioxamycin.

    PubMed

    Matsumoto, M; Kawamura, Y; Yasuda, Y; Tanimoto, T; Matsumoto, K; Yoshida, T; Shoji, J

    1989-10-01

    A new peptide antibiotic named thioxamycin which contained thiazole and oxazole rings was isolated from the culture broth of Streptomyces sp. The antibiotic is acidic and lipophilic in nature. A molecular formula, C52H48N16O15S4, was indicated by elemental analysis and MS. One mol of threonine and three unusual amino acids were detected by amino acid analysis of the acid hydrolysate. The antibiotic is active in vitro against anaerobic Gram-positive and Gram-negative bacteria and also aerobic Gram-positive bacteria. PMID:2808134

  5. Classification and identification of pigmented cocci bacteria relevant to the soil environment via Raman spectroscopy.

    PubMed

    Kumar, Vinay; Kampe, Bernd; Rösch, Petra; Popp, Jürgen

    2015-12-01

    A soil habitat consists of a significant number of bacteria that cannot be cultivated by conventional means, thereby posing obvious difficulties in their classification and identification. This difficulty necessitates the need for advanced techniques wherein a well-compiled biomolecular database consisting of the already cultivable bacteria can be used as a reference in an attempt to link the noncultivable bacteria to their closest phylogenetic groups. Raman spectroscopy has been successfully applied to taxonomic studies of many systems like bacteria, fungi, and plants relying on spectral differences contributed by the variation in their overall biomolecular composition. However, these spectral differences can be obscured due to Raman signatures from photosensitive microbial pigments like carotenoids that show enormous variation in signal intensity hindering taxonomic investigations. In this study, we have applied laser-induced photobleaching to expel the carotenoid signatures from pigmented cocci bacteria. Using this method, we have investigated 12 species of pigmented bacteria abundant in soil habitats belonging to three genera mainly Micrococcus, Deinococcus, and Kocuria based on their Raman spectra with the assistance of a chemometric tool known as the radial kernel support vector machine (SVM). Our results demonstrate the potential of Raman spectroscopy as a minimally invasive taxonomic tool to identify pigmented cocci soil bacteria at a single-cell level. PMID:25940486

  6. Performance Evaluation of the Verigene Gram-Positive and Gram-Negative Blood Culture Test for Direct Identification of Bacteria and Their Resistance Determinants from Positive Blood Cultures in Hong Kong

    PubMed Central

    Siu, Gilman K. H.; Chen, Jonathan H. K.; Ng, T. K.; Lee, Rodney A.; Fung, Kitty S. C.; To, Sabrina W. C.; Wong, Barry K. C.; Cheung, Sherman; Wong, Ivan W. F.; Tam, Marble M. P.; Lee, Swing S. W.; Yam, W. C.

    2015-01-01

    Background A multicenter study was conducted to evaluate the diagnostic performance and the time to identifcation of the Verigene Blood Culture Test, the BC-GP and BC-GN assays, to identify both Gram-positive and Gram-negative bacteria and their drug resistance determinants directly from positive blood cultures collected in Hong Kong. Methods and Results A total of 364 blood cultures were prospectively collected from four public hospitals, in which 114 and 250 cultures yielded Gram-positive and Gram-negative bacteria, and were tested with the BC-GP and BC-GN assay respectively. The overall identification agreement for Gram-positive and Gram-negative bacteria were 89.6% and 90.5% in monomicrobial cultures and 62.5% and 53.6% in polymicrobial cultures, respectively. The sensitivities for most genus/species achieved at least 80% except Enterococcus spp. (60%), K.oxytoca (0%), K.pneumoniae (69.2%), whereas the specificities for all targets ranged from 98.9% to 100%. Of note, 50% (7/14) cultures containing K.pneumoniae that were missed by the BC-GN assay were subsequently identified as K.variicola. Approximately 5.5% (20/364) cultures contained non-target organisms, of which Aeromonas spp. accounted for 25% and are of particular concern. For drug resistance determination, the Verigene test showed 100% sensitivity for identification of MRSA, VRE and carbapenem resistant Acinetobacter, and 84.4% for ESBL-producing Enterobacteriaceae based on the positive detection of mecA, vanA, blaOXA and blaCTXM respectively. Conclusion Overall, the Verigene test provided acceptable accuracy for identification of bacteria and resistance markers with a range of turnaround time 40.5 to 99.2 h faster than conventional methods in our region. PMID:26431434

  7. An application of polymer-enhanced capillary transient isotachophoresis with an emissive boronic acid functionalized squarylium dye as an on-capillary labeling agent for gram-positive bacteria.

    PubMed

    Saito, Shingo; Maeda, Takeshi; Nakazumi, Hiroyuki; Colyer, Christa L

    2013-01-01

    In this paper, the characterization and application of the "PectI" (polymer-enhanced capillary transient isotachophoresis) technique for the separation and detection of same genus, gram-positive bacteria, Bacillus globigii (Bg) and Bacillus subtilis, is demonstrated by employing a boronic acid-functionalized squarylium dye (SQ-BA) as an on-capillary labeling agent, including the quantitative performance and applicability to crude samples. The effect of borate in the separation buffer was also investigated, which revealed that borate strongly affects the separation behavior of bacteria. PMID:23303103

  8. Antimicrobial activity of Calendula officinalis petal extracts against fungi, as well as Gram-negative and Gram-positive clinical pathogens.

    PubMed

    Efstratiou, Efstratios; Hussain, Abdullah I; Nigam, Poonam S; Moore, John E; Ayub, Muhammad A; Rao, Juluri R

    2012-08-01

    The aim of the present study was to assess the antimicrobial activity of methanol and ethanol extracts of pot marigold (Calendula officinalis) petals against clinical pathogens. The antimicrobial potential of C. officinalis extracts was evaluated against a panel of microorganisms isolated from patients at the Belfast City Hospital (BCH), including bacteria and fungi, using disc diffusion assay. Methanol extract of C. officinalis exhibited better antibacterial activity against most of the bacteria tested, than ethanol extract. Both methanol and ethanol extracts showed excellent antifungal activity against tested strains of fungi, while comparing with Fluconazole. PMID:22789794

  9. Short-term effects of temperature on the abundance and diversity of magnetotactic cocci.

    PubMed

    Lin, Wei; Wang, Yinzhao; Pan, Yongxin

    2012-03-01

    Temperature is one of the most important climate factors that can regulate the activity and growth of organisms. However, it is so far unclear how temperature influences the abundance and community composition of magnetotactic bacteria (MTB) that mineralize intracellular magnetite and/or greigite magnetosomes and play significant roles in the global iron cycling and sediment magnetization. To address this specific problem, in this study we have assessed the impact of temperature on freshwater magnetotactic cocci through laboratory microcosm simulations. Microcosms containing MTB were exposed to four constant temperatures ranging from 9°C to 37°C. After 10 days and 28 days of incubation, no significant differences in abundance were detected in microcosms at 9°C, 15°C, and 26°C (Student's t-test, P > 0.05); however, microcosms exposed to 37°C exhibited a significant decrease of magnetotactic cocci abundance (P < 0.05). Dendrogram analysis of community-amplified ribosomal DNA restriction analysis (community ARDRA) banding patterns distinguished the 37°C samples from samples at lower temperatures regardless of incubation periods. Furthermore, clone library analysis revealed that most of the operational taxonomic units (OTUs) detected in samples from 9°C to 26°C were absent from the 37°C microcosms, whereas six OTUs were exclusively detected in the 37°C samples. Community compositions from four incubation temperatures were further compared using statistical phylogenetic methods (UniFrac and LIBSHUFF), which revealed that the 37°C samples harbored phylogenetically distinct MTB communities compared to those found in 9°C, 15°C, and 26°C samples. Taken together, our results indicate that elevated temperature can influence the abundance and diversity of dominant members of magnetotactic cocci. This linkage further infers that the abundance and diversity of MTB (e.g., based on the fossil magnetosomes) may be useful in reconstruction of paleotemperature. PMID

  10. Short-term effects of temperature on the abundance and diversity of magnetotactic cocci

    PubMed Central

    Lin, Wei; Wang, Yinzhao; Pan, Yongxin

    2012-01-01

    Temperature is one of the most important climate factors that can regulate the activity and growth of organisms. However, it is so far unclear how temperature influences the abundance and community composition of magnetotactic bacteria (MTB) that mineralize intracellular magnetite and/or greigite magnetosomes and play significant roles in the global iron cycling and sediment magnetization. To address this specific problem, in this study we have assessed the impact of temperature on freshwater magnetotactic cocci through laboratory microcosm simulations. Microcosms containing MTB were exposed to four constant temperatures ranging from 9°C to 37°C. After 10 days and 28 days of incubation, no significant differences in abundance were detected in microcosms at 9°C, 15°C, and 26°C (Student's t-test, P > 0.05); however, microcosms exposed to 37°C exhibited a significant decrease of magnetotactic cocci abundance (P < 0.05). Dendrogram analysis of community-amplified ribosomal DNA restriction analysis (community ARDRA) banding patterns distinguished the 37°C samples from samples at lower temperatures regardless of incubation periods. Furthermore, clone library analysis revealed that most of the operational taxonomic units (OTUs) detected in samples from 9°C to 26°C were absent from the 37°C microcosms, whereas six OTUs were exclusively detected in the 37°C samples. Community compositions from four incubation temperatures were further compared using statistical phylogenetic methods (UniFrac and LIBSHUFF), which revealed that the 37°C samples harbored phylogenetically distinct MTB communities compared to those found in 9°C, 15°C, and 26°C samples. Taken together, our results indicate that elevated temperature can influence the abundance and diversity of dominant members of magnetotactic cocci. This linkage further infers that the abundance and diversity of MTB (e.g., based on the fossil magnetosomes) may be useful in reconstruction of paleotemperature. PMID

  11. Identification and characterization of lactococcal and Acetobacter strains isolated from traditional Caucasusian fermented milk.

    PubMed

    Ishida, Tatsuya; Yokota, Akira; Umezawa, Yuka; Toda, Toshiya; Yamada, Kazuhiko

    2005-06-01

    The fermented milk, so-called "Caspian Sea Yogurt" in Japan, consists of two bacterial strains isolated from traditional Caucasusian fermented milk. In the present study, those strains were identified and characterized. Strain FC was Gram-positive, facultatively anaerobic cocci and strain FA was Gram-negative, aerobic rods. Phylogenetic analysis based on 16S rDNA sequences showed that strain FC formed a cluster with Lactococcus lactis strains and was most closely related to L. lactis subsp. cremoris. Strain FA was included in the genus Acetobacter cluster and was most closely related to A. orientalis. The DNA G+C contents of strain FC and strain FA were 39.2 and 51.6 mol%, respectively. Biochemical tests and DNA-DNA hybridization clarified that strain FC belongs to L. lactis subsp. cremoris and strain FA belongs to A. orientalis. The culture supernatant of lactococcal strain FC inhibited the growth of L. lactis subsp. cremoris DSM 20069T and L. lactis subsp. hordniae JCM 1180T. The inhibitory activity was detected after incubation at 70 degrees C for 60 min or 100 degrees C for 30 min and was stable when the supernatant was adjusted to a pH ranging from 4.9 to 7.5. The antimicrobial activity was lost on treatment with proteolytic enzymes such as proteinase K, trypsin, pronase, and pepsin, although it was not affected by catalase. The gene of lactococcin B (lcnB) homolog was found in the strain FC. From the above results, the strain FC was thought to produce a bacteriocin-like substance. PMID:16161770

  12. Streptococcus sinensis sp. nov., a novel species isolated from a patient with infective endocarditis.

    PubMed

    Woo, Patrick C Y; Tam, Dorothy M W; Leung, Kit-Wah; Lau, Susanna K P; Teng, Jade L L; Wong, Michelle K M; Yuen, Kwok-Yung

    2002-03-01

    A bacterium was isolated from the blood culture of a patient with infective endocarditis. The cells were facultative anaerobic, nonsporulating, gram-positive cocci arranged in chains. The bacterium grows on sheep blood agar as alpha-hemolytic, gray colonies of 0.5 to 1 mm in diameter after 24 h of incubation at 37 degrees C in ambient air. Growth also occurs in 10 or 40% bile and on bile esculin agar but not in 6% NaCl. No enhancement of growth is observed in 5% CO(2). It is nongroupable with Lancefield groups A, B, C, D, F, or G antisera and is resistant to optochin and bacitracin. The organism is aflagellated and is nonmotile at both 25 and 37 degrees C. It is Voges-Proskauer test positive. It produces leucine arylamidase and beta-glucosidase but not catalase, urease, lysine decarboxylase, or ornithine decarboxylase. It hydrolyzes esculin and arginine. It utilizes glucose, lactose, salicin, sucrose, pullulan, trehalose, cellobiose, hemicellulase, mannose, maltose, and starch. 16S rRNA gene sequencing showed that there were 3.6, 3.7, 4.3, 4.7, and 5.9% differences between the 16S rRNA gene sequence of the bacterium and those of Streptococcus gordonii, Streptococcus intermedius, Streptococcus constellatus, Streptococcus sanguis, and Streptococcus anginosus, respectively. The G+C content of it (mean plus minus standard deviation) was 53.0% plus minus 2.9%. Based on phylogenetic affiliation, it belongs to the mitis or anginosus group of Streptococcus. For these reasons a new species, Streptococcus sinensis sp. nov., is proposed, for which HKU4 is the type strain. Further studies should be performed to ascertain the potential of this bacterium to become an emerging cause of infective endocarditis. PMID:11880397

  13. Bacillus subtilis subsp. subtilis CBMDC3f with antimicrobial activity against Gram-positive foodborne pathogenic bacteria: UV-MALDI-TOF MS analysis of its bioactive compounds.

    PubMed

    Torres, M J; Petroselli, G; Daz, M; Erra-Balsells, R; Audisio, M C

    2015-06-01

    In this work a new Bacillus sp. strain, isolated from honey, was characterized phylogenetically. Its antibacterial activity against three relevant foodborne pathogenic bacteria was studied; the main bioactive metabolites were analyzed using ultraviolet matrix assisted laser desorption-ionization mass spectrometry (UV-MALDI MS). Bacillus CBMDC3f was phylogenetically characterized as Bacillus subtilis subsp. subtilis after rRNA analysis of the 16S subunit and the gyrA gene (access codes Genbank JX120508 and JX120516, respectively). Its antibacterial potential was evaluated against Listeria monocytogenes (9 strains), B. cereus (3 strains) and Staphylococcus aureus ATCC29213. Its cell suspension and cell-free supernatant (CFS) exerted significant anti-Listeria and anti-S. aureus activities, while the lipopeptides fraction (LF) also showed anti-B. cereus effect. The UV-MALDI-MS analysis revealed surfactin, iturin and fengycin in the CFS, whereas surfactin predominated in the LF. The CFS from CBMDC3f contained surfactin, iturin and fengycin with four, two and four homologues per family, respectively, whereas four surfactin, one iturin and one fengycin homologues were identified in the LF. For some surfactin homologues, their UV-MALDI-TOF/TOF (MS/MS; Laser Induced Decomposition method, LID) spectra were also obtained. Mass spectrometry analysis contributed with relevant information about the type of lipopeptides that Bacillus strains can synthesize. From our results, surfactin would be the main metabolite responsible for the antibacterial effect. PMID:25820813

  14. Draft genome sequence analysis of a Pseudomonas putida W15Oct28 strain with antagonistic activity to Gram-positive and Pseudomonas sp. pathogens.

    PubMed

    Ye, Lumeng; Hildebrand, Falk; Dingemans, Jozef; Ballet, Steven; Laus, George; Matthijs, Sandra; Berendsen, Roeland; Cornelis, Pierre

    2014-01-01

    Pseudomonas putida is a member of the fluorescent pseudomonads known to produce the yellow-green fluorescent pyoverdine siderophore. P. putida W15Oct28, isolated from a stream in Brussels, was found to produce compound(s) with antimicrobial activity against the opportunistic pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and the plant pathogen Pseudomonas syringae, an unusual characteristic for P. putida. The active compound production only occurred in media with low iron content and without organic nitrogen sources. Transposon mutants which lost their antimicrobial activity had the majority of insertions in genes involved in the biosynthesis of pyoverdine, although purified pyoverdine was not responsible for the antagonism. Separation of compounds present in culture supernatants revealed the presence of two fractions containing highly hydrophobic molecules active against P. aeruginosa. Analysis of the draft genome confirmed the presence of putisolvin biosynthesis genes and the corresponding lipopeptides were found to contribute to the antimicrobial activity. One cluster of ten genes was detected, comprising a NAD-dependent epimerase, an acetylornithine aminotransferase, an acyl CoA dehydrogenase, a short chain dehydrogenase, a fatty acid desaturase and three genes for a RND efflux pump. P. putida W15Oct28 genome also contains 56 genes encoding TonB-dependent receptors, conferring a high capacity to utilize pyoverdines from other pseudomonads. One unique feature of W15Oct28 is also the presence of different secretion systems including a full set of genes for type IV secretion, and several genes for type VI secretion and their VgrG effectors. PMID:25369289

  15. Suicin 90-1330 from a Nonvirulent Strain of Streptococcus suis: a Nisin-Related Lantibiotic Active on Gram-Positive Swine Pathogens

    PubMed Central

    LeBel, Geneviève; Vaillancourt, Katy; Frenette, Michel; Gottschalk, Marcelo

    2014-01-01

    Streptococcus suis serotype 2 is known to cause severe infections (meningitis, endocarditis, and septicemia) in pigs and is considered an emerging zoonotic agent. Antibiotics have long been used in the swine industry for disease treatment/prevention and growth promoters. This pattern of utilization resulted in the spread of antibiotic resistance in S. suis worldwide. Interestingly, pigs may harbor S. suis in their tonsils without developing diseases, while North American strains belonging to the sequence type 28 (ST28) are nonvirulent in animal models. Consequently, the aim of this study was to purify and characterize a bacteriocin produced by a nonvirulent strain of S. suis serotype 2, with a view to a potential therapeutic and preventive application. S. suis 90-1330 belonging to ST28 and previously shown to be nonvirulent in an animal model exhibited antibacterial activity toward all S. suis pathogenic isolates tested. The bacteriocin produced by this strain was purified to homogeneity by cationic exchange and reversed-phase fast protein liquid chromatography. Given its properties (molecular mass of <4 kDa, heat, pH and protease stability, and the presence of modified amino acids), the bacteriocin, named suicin 90-1330, belongs to the lantibiotic class. Using a DNA-binding fluorophore, the bacteriocin was found to possess a membrane permeabilization activity. When tested on other swine pathogens, the suicin showed activity against Staphylococcus hyicus and Staphylococcus aureus, whereas it was inactive against all Gram-negative bacteria tested. Amino acid sequencing of the purified bacteriocin showed homology (90.9% identity) with nisin U produced by Streptococcus uberis. The putative gene cluster involved in suicin production was amplified by PCR and sequence analysis revealed the presence of 11 open reading frames, including the structural gene and those required for the modification of amino acids, export, regulation, and immunity. Further studies will

  16. Suicin 90-1330 from a nonvirulent strain of Streptococcus suis: a nisin-related lantibiotic active on gram-positive swine pathogens.

    PubMed

    LeBel, Geneviève; Vaillancourt, Katy; Frenette, Michel; Gottschalk, Marcelo; Grenier, Daniel

    2014-09-01

    Streptococcus suis serotype 2 is known to cause severe infections (meningitis, endocarditis, and septicemia) in pigs and is considered an emerging zoonotic agent. Antibiotics have long been used in the swine industry for disease treatment/prevention and growth promoters. This pattern of utilization resulted in the spread of antibiotic resistance in S. suis worldwide. Interestingly, pigs may harbor S. suis in their tonsils without developing diseases, while North American strains belonging to the sequence type 28 (ST28) are nonvirulent in animal models. Consequently, the aim of this study was to purify and characterize a bacteriocin produced by a nonvirulent strain of S. suis serotype 2, with a view to a potential therapeutic and preventive application. S. suis 90-1330 belonging to ST28 and previously shown to be nonvirulent in an animal model exhibited antibacterial activity toward all S. suis pathogenic isolates tested. The bacteriocin produced by this strain was purified to homogeneity by cationic exchange and reversed-phase fast protein liquid chromatography. Given its properties (molecular mass of <4 kDa, heat, pH and protease stability, and the presence of modified amino acids), the bacteriocin, named suicin 90-1330, belongs to the lantibiotic class. Using a DNA-binding fluorophore, the bacteriocin was found to possess a membrane permeabilization activity. When tested on other swine pathogens, the suicin showed activity against Staphylococcus hyicus and Staphylococcus aureus, whereas it was inactive against all Gram-negative bacteria tested. Amino acid sequencing of the purified bacteriocin showed homology (90.9% identity) with nisin U produced by Streptococcus uberis. The putative gene cluster involved in suicin production was amplified by PCR and sequence analysis revealed the presence of 11 open reading frames, including the structural gene and those required for the modification of amino acids, export, regulation, and immunity. Further studies will

  17. Next Science Wound Gel Technology, a Novel Agent That Inhibits Biofilm Development by Gram-Positive and Gram-Negative Wound Pathogens

    PubMed Central

    Miller, Kyle G.; Tran, Phat L.; Haley, Cecily L.; Kruzek, Cassandra; Colmer-Hamood, Jane A.; Myntti, Matt

    2014-01-01

    Loss of the skin barrier facilitates the colonization of underlying tissues with various bacteria, where they form biofilms that protect them from antibiotics and host responses. Such wounds then become chronically infected. Topical antimicrobials are a major component of chronic wound therapy, yet currently available topical antimicrobials vary in their effectiveness on biofilm-forming pathogens. In this study, we evaluated the efficacy of Next Science wound gel technology (NxtSc), a novel topical agent designed to kill planktonic bacteria, penetrate biofilms, and kill the bacteria within. In vitro quantitative analysis, using strains isolated from wounds, showed that NxtSc inhibited biofilm development by Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae by inhibiting bacterial growth. The gel formulation NxtSc-G5, when applied to biofilms preformed by these pathogens, reduced the numbers of bacteria present by 7 to 8 log10 CFU/disc or CFU/g. In vivo, NxtSc-G5 prevented biofilm formation for 72 h when applied at the time of wounding and infection and eliminated biofilm infection when applied 24 h after wounding and infection. Storage of NxtSc-G5 at room temperature for 9 months did not diminish its efficacy. These results establish that NxtSc is efficacious in vitro and in vivo in preventing infection and biofilm development by different wound pathogens when applied immediately and in eliminating biofilm infection already established by these pathogens. This novel antimicrobial agent, which is nontoxic and has a usefully long shelf life, shows promise as an effective agent for the prevention and treatment of biofilm-related infections. PMID:24637684

  18. Draft Genome Sequence Analysis of a Pseudomonas putida W15Oct28 Strain with Antagonistic Activity to Gram-Positive and Pseudomonas sp. Pathogens

    PubMed Central

    Ye, Lumeng; Hildebrand, Falk; Dingemans, Jozef; Ballet, Steven; Laus, George; Matthijs, Sandra; Berendsen, Roeland; Cornelis, Pierre

    2014-01-01

    Pseudomonas putida is a member of the fluorescent pseudomonads known to produce the yellow-green fluorescent pyoverdine siderophore. P. putida W15Oct28, isolated from a stream in Brussels, was found to produce compound(s) with antimicrobial activity against the opportunistic pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and the plant pathogen Pseudomonas syringae, an unusual characteristic for P. putida. The active compound production only occurred in media with low iron content and without organic nitrogen sources. Transposon mutants which lost their antimicrobial activity had the majority of insertions in genes involved in the biosynthesis of pyoverdine, although purified pyoverdine was not responsible for the antagonism. Separation of compounds present in culture supernatants revealed the presence of two fractions containing highly hydrophobic molecules active against P. aeruginosa. Analysis of the draft genome confirmed the presence of putisolvin biosynthesis genes and the corresponding lipopeptides were found to contribute to the antimicrobial activity. One cluster of ten genes was detected, comprising a NAD-dependent epimerase, an acetylornithine aminotransferase, an acyl CoA dehydrogenase, a short chain dehydrogenase, a fatty acid desaturase and three genes for a RND efflux pump. P. putida W15Oct28 genome also contains 56 genes encoding TonB-dependent receptors, conferring a high capacity to utilize pyoverdines from other pseudomonads. One unique feature of W15Oct28 is also the presence of different secretion systems including a full set of genes for type IV secretion, and several genes for type VI secretion and their VgrG effectors. PMID:25369289

  19. Phycicoccus badiiscoriae sp. nov., a novel actinomycete isolated from scoria.

    PubMed

    Lee, Soon Dong

    2013-03-01

    An actinomycete strain, designated Sco-B23(T), was isolated from a brown-coloured layer of scoria collected near Darangshi Oreum (a small mountain) in Jeju, Republic of Korea. Cells of the organism were Gram-positive, non-endospore-forming, non-motile cocci and grew at 20-35 °C, at pH 5.1-11.1 and with 0-1 % (w/v) NaCl. Colonies were circular, translucent and moderate yellow in colour with entire margins. On the basis of 16S rRNA gene sequence analysis, the isolate belonged to the genus Phycicoccus and formed a monophyletic line between a Phycicoccus bigeumensis-Phycicoccus dokdonensis cluster and a Phycicoccus aerophilus-Phycicoccus ginsenosidimutans cluster. Levels of 16S rRNA gene sequence similarity between strain Sco-B23(T) and the type strains of Phycicoccus species were: P. bigeumensis (98.8 %), P. dokdonensis (98.7 %), P. aerophilus (97.7 %), P. ginsenosidimutans (97.7 %), P. cremeus (96.9 %) and P. jejuensis (96.5 %). Chemotaxonomic analyses showed that the isolate possessed meso-diaminopimelic acid as the diamino acid of the peptidoglycan, MK-8(H4) as the predominant menaquinone, a polar lipid profile including diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unknown phospholipid and two unknown lipids, predominant fatty acids represented by iso-C15 : 0, C17 : 1cis9, iso-C16 : 0 and iso-C14 : 0, and DNA G+C content of 69.7 mol%. DNA-DNA relatedness between strain Sco-B23(T) and the close relatives within the genus Phycicoccus was below 18.1 %. On the basis of phenotypic features and DNA-DNA hybridization data, strain Sco-B23(T) represents a novel species of the genus Phycicoccus, for which the name Phycicoccus badiiscoriae sp. nov. is proposed. The type strain is Sco-B23(T) ( = KCTC 19807(T)  = KACC 15111(T)  = NBRC 107918(T)). PMID:22685104

  20. First Comprehensive Evaluation of the M.I.C. Evaluator Device Compared to Etest and CLSI Broth Microdilution for MIC Testing of Aerobic Gram-Positive and Gram-Negative Bacterial Species

    PubMed Central

    Turnbull, L.; Brosnikoff, C.; Cloke, J.

    2012-01-01

    The M.I.C. Evaluator strip (Thermo Fisher Scientific, Basingstoke, United Kingdom) uses a methodology similar to that of Etest. In this first assessment of the M.I.C. Evaluator device, 409 strains of aerobic Gram-positive bacteria (staphylococci, streptococci, and enterococci) and 325 strains of Enterobacteriaceae, Pseudomonas species, and Acinetobacter species were tested by M.I.C. Evaluator strip, Etest, and broth microdilution as a reference standard. The Gram-positive bacteria included staphylococci (methicillin-resistant Staphylococcus aureus, methicillin-susceptible S. aureus, and coagulase-negative staphylococci), Streptococcus pneumoniae, beta-hemolytic streptococci and viridians group strains, vancomycin-resistant enterococci, and other enterococci. The Gram-negative bacteria included 250 strains of 60 Enterobacteriaceae species plus 50 Pseudomonas and 25 Acinetobacter species. A total of 14 antimicrobial agents (depending on the species) were included. The same methodology and reading format were used for M.I.C. Evaluator strips and Etest. Broth microdilution methodology was performed according to CLSI document M07-A8. For the clinical strains, >95% of results were plus or minus one doubling dilution for all species. There were fewer than 5% minor errors, fewer than 3% major errors, and fewer than 1% very major errors. M.I.C. Evaluator strips and Etest often reported higher MICs than the reference broth microdilution method. The M.I.C. Evaluator strips provided results comparable to those of the predicate Etest device and are of value for the accurate testing of MICs for these important pathogens. PMID:22238441

  1. Bacillus glycinifermentans sp. nov., isolated from fermented soybean paste

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two independent isolates of a Gram-positive, aerobic, motile rod-shaped bacterium were recovered from soybean-based fermented foodstuffs. Two were isolated from cheonggukjang, a Korean fermented soybean food product. Multilocus sequencing analysis of the 16S rRNA gene and 5 protein coding genes indi...

  2. Bacillus paralicheniformis sp. nov., isolated from fermented soybean paste

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An isolate of a Gram-positive, facultatively anaerobic, motile, rod-shaped, endospore forming bacterium was recovered from soybean-based fermented paste. It was isolated from cheonggukjang, a Korean fermented soybean food product. Phylogenetic analysis of the 16S rRNA gene indicated that the strain ...

  3. Jeotgalicoccus halotolerans gen. nov., sp. nov. and Jeotgalicoccus psychrophilus sp. nov., isolated from the traditional Korean fermented seafood jeotgal.

    PubMed

    Yoon, Jung-Hoon; Lee, Keun-Chul; Weiss, Norbert; Kang, Kook Hee; Park, Yong-Ha

    2003-03-01

    Two Gram-positive, non-motile, non-spore-forming, halotolerant and moderately halophilic cocci (strains YKJ-101T and YKJ-115T) were isolated from the traditional Korean fermented seafood jeotgal, and were investigated using a polyphasic taxonomic approach. Phylogenetic analysis of 16S rDNA sequences showed that strains YKJ-101T and YKJ-115T are most closely related to the cluster comprising two Salinicoccus species. The peptidoglycan type of the strains is A3alpha, based on L-Lys-Gly(3-4)-L-Ala(Gly), and the predominant menaquinone is MK-7. Strains YKJ-101T and YKJ-115T have cellular fatty acid profiles containing major amounts of saturated, unsaturated and branched fatty acids; the major fatty acids are anteiso-C15 : 0 and iso-C15 : 0. The cellular polar lipids are phosphatidylglycerol, diphosphatidylglycerol and unidentified phospholipids. Strains YKJ-101T and YKJ-115T have identical DNA G + C contents of 42 mol%. The 16S rDNA similarity between strains YKJ-101T and YKJ-115T is 98% and the mean level of DNA-DNA relatedness between the two strains is 13.4%. On the basis of phenotypic and phylogenetic data and genomic distinctiveness, it is proposed that strains YKJ-101T and YKJ-115T should be placed in a new genus, Jeotgalicoccus gen. nov., as two distinct new species, for which the names Jeotgalicoccus halotolerans sp. nov. and Jeotgalicoccus psychrophilus sp. nov. are proposed. The type strains are YKJ-101T (=KCCM 41448T =JCM 11198T) and YKJ-115T (=KCCM 41449T =JCM 11199T), respectively. PMID:12710632

  4. Effect of autochthonous starter cultures isolated from Siahmazgi cheese on physicochemical, microbiological and volatile compound profiles and sensorial attributes of sucuk, a Turkish dry-fermented sausage.

    PubMed

    Kargozari, Mina; Moini, Sohrab; Akhondzadeh Basti, Afshin; Emam-Djomeh, Zahra; Gandomi, Hassan; Revilla Martin, Isabel; Ghasemlou, Mehran; Carbonell-Barrachina, Angel A

    2014-05-01

    The effect of adding autochthonous starter cultures isolated from Siahmazgi cheese, on the physicochemical parameters and microbial counts of sucuk was investigated during the ripening period. SPME-GC/MS was used in volatile compound analysis and a trained group of panelists carried out sensory analysis of the final product. After preliminary screening, three strains of Lactobacillus plantarum, which possess desirable technological properties, were used to prepare three starter cultures: LBP7, LBP10 and LBP14. The addition of LBP7 and LBP14 starter cultures had a significant effect (P<0.05) on lightness, leading to higher L values compared to control sausages during the ripening period. Both LBP7 and LBP14 sausages showed higher counts of lactic acid bacteria, lower growth of Enterobacteriaceae and Gram-positive catalase-positive cocci and greatly lowered the pH value compared to control sausages throughout the ripening process. At the end of the ripening process, lactic acid bacteria counts were affected (P<0.05) by the addition of starter culture since higher counts were observed in sausages prepared with LBP7 (9.14logCFU/g) and LBP14 (8.96logCFU/g) batches. The decrease of water activity during the ripening of sausages was not affected by the various starters. The texture profiles of all sausages were similar except for LBP10, which showed lower hardness and gumminess during ripening. Under the conditions of the study, volatile compounds were mainly from spices, and no marked differences were found among inoculated sausages. However, sensory evaluation revealed that most of the sensory attributes were scored higher for inoculated sausages than for the control ones. Therefore, LBP7 and LBP14 could be promising candidates for inclusion as starter cultures for the manufacture of sucuk. PMID:24553492

  5. In vivo metabolism of 2,2 prime -diaminopimelic acid from gram-positive and gram-negative bacterial cells by ruminal microorganisms and ruminants and its use as a marker of bacterial biomass

    SciTech Connect

    Masson, H.A.; Denholm, A.M.; Ling, J.R. )

    1991-06-01

    Cells of Bacillus megaterium GW1 and Escherichia coli W7-M5 were specifically radiolabeled with 2,2{prime}-diamino (G-{sup 3}H) pimelic acid (({sup 3}H)DAP) as models of gram-positive and gram-negative bacteria, respectively. Two experiments were conducted to study the in vivo metabolism of 2,2{prime}-diaminopimelic acid (DAP) in sheep. In experiment 1, cells of ({sup 3}H)DAP-labeled B. megaterium GW1 were infused into the rumen of one sheep and the radiolabel was traced within microbial samples, digesta, and the whole animal. Bacterially bound ({sup 3}H)DAP was extensively metabolized, primarily (up to 70% after 8 h) via decarboxylation to ({sup 3}H)lysine by both ruminal protozoa and ruminal bacteria. Recovery of infused radiolabel in urine and feces was low (42% after 96 h) and perhaps indicative of further metabolism by the host animal. In experiment 2, ({sup 3}H)DAP-labeled B. megaterium GW1 was infused into the rumens of three sheep and ({sup 3}H)DAP-labeled E. coli W7-W5 was infused into the rumen of another sheep. The radioactivity contents of these mutant bacteria were insufficient to use as tracers, but the metabolism of DAP was monitored in the total, free, and peptidyl forms. Free DAP, as a proportion of total DPA in duodenal digesta, varied from 0 to 9.5%, whereas peptidyl DAP accounted for 8.3 to 99.2%.

  6. H2M3wt-restricted, Listeria monocytogenes-immune CD8 T cells respond to multiple formylated peptides and to a variety of gram-positive and gram-negative bacteria.

    PubMed

    Nataraj, C; Huffman, G R; Kurlander, R J

    1998-01-01

    A subset of H2M3wt-restricted, Listeria monocytogenes (LM)-immune CD8 effectors recognize antigen-presenting cells (APC) preincubated with heat-killed LM. The responsible product, which we have previously designated heat-killed Listeria-associated antigen (HAA), is extremely hydrophobic and resistant to proteolytic degradation. Despite the protease resistance of HAA, we now report that HAA-immune clones are uniformly responsive to fMIGWII, a formylated oligopeptide derived from the recently described LM product, lemA. While fMIGWII was by far the most potent peptide tested, over half our clones also responded to the LM-derived peptide fMIVII and cross-reactive responses to two other unrelated formylated peptides at concentrations of <1 microM were frequently observed. One of these peptides (fBlaZ) did not share any amino acid in common with fMIGWII except N-formyl methionine at position 1. Unformylated variants of the same peptides were inactive. HAA-immune CD8 cells also responded in an H2M3wt-restricted manner to APC pretreated with heat-killed or live preparations of other gram-positive and gram-negative bacteria such as Streptococcus pyogenes (SP) and Proteus vulgaris (PV). Unlike fMIGWII which is water soluble and protease sensitive, the native antigens extracted from SP and PV, like HAA, were very hydrophobic and proteinase K resistant, presumably reflecting in each case the association of cross-reactive polypeptides with bacterial lipid or phospholipid. Thus, HAA/lemA-immune, H2M3wt-restricted effectors can respond to a variety of formylated peptides and bacterial antigens in vitro. Similar cross-reactions in vivo might have physiologically significant implications. PMID:9488151

  7. Thermobaculum terrenum gen. nov., sp. nov.: a non-phototrophic gram-positive thermophile representing an environmental clone group related to the Chloroflexi (green non-sulfur bacteria) and Thermomicrobia.

    PubMed

    Botero, Lina M; Brown, Kathy B; Brumefield, Sue; Burr, Mark; Castenholz, Richard W; Young, Mark; McDermott, Timothy R

    2004-04-01

    A novel bacterium was cultivated from an extreme thermal soil in Yellowstone National Park, Wyoming, USA, that at the time of sampling had a pH of 3.9 and a temperature range of 65-92 degrees C. This organism was found to be an obligate aerobic, non-spore-forming rod, and formed pink-colored colonies. Phylogenetic analysis of the 16S rRNA gene sequence placed this organism in a clade composed entirely of environmental clones most closely related to the phyla Chloroflexi and Thermomicrobia. This bacterium stained gram-positive, contained a novel fatty-acid profile, had cell wall muramic acid content similar to that of Bacillus subtilis (significantly greater than Escherichia coli), and failed to display a lipopolysaccharide profile in SDS-polyacrylamide gels that would be indicative of a gram-negative cell wall structure. Ultrastructure examinations with transmission electron microscopy showed a thick cell wall (approximately 34 nm wide) external to a cytoplasmic membrane. The organism was not motile under the culture conditions used, and electron microscopic examination showed no evidence of flagella. Genomic G+C content was 56.4 mol%, and growth was optimal at 67 degrees C and at a pH of 7.0. This organism was able to grow heterotrophically on various carbon compounds, would use only oxygen as an electron acceptor, and its growth was not affected by light. A new species of a novel genus is proposed, with YNP1(T) (T=type strain) being Thermobaculum terrenum gen. nov., sp. nov. (16S rDNA gene GenBank accession AF391972). This bacterium has been deposited in the American Type Culture Collection (ATCC BAA-798) and the University of Oregon Culture Collection of Microorganisms from Extreme Environments (CCMEE 7001). PMID:14745485

  8. Peptostreptococcus russellii sp. nov., isolated from a swine-manure storage pit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A polyphasic taxonomic study was performed on seven strains of an unknown Gram-positive, nonspore-forming, obligately anaerobic coccus-shaped bacterium isolated from a swine-manure storage pit. Comparative 16S rRNA gene sequencing confirmed that all these isolates were highly related to each other ...

  9. Genome sequence of Clostridium tunisiense TJ, isolated from drain sediment from a pesticide factory.

    PubMed

    Sun, Lili; Wang, Yu; Yu, Chunyan; Zhao, Yongqin; Gan, Yinbo

    2012-12-01

    Clostridium tunisiense is a Gram-positive, obligate anaerobe that was first isolated in an anaerobic environment under eutrophication. Here we report the first genome sequence of the Clostridium tunisiense TJ isolated from drain sediment of a pesticide factory in Tianjin, China. The genome is of great importance for both basic and application research. PMID:23209212

  10. Transcriptional cross-regulation between Gram-negative and gram-positive bacteria, demonstrated using ArgP-argO of Escherichia coli and LysG-lysE of Corynebacterium glutamicum.

    PubMed

    Marbaniang, Carmelita N; Gowrishankar, J

    2012-10-01

    The protein-gene pairs ArgP-argO of Escherichia coli and LysG-lysE of Corynebacterium glutamicum are orthologous, with the first member of each pair being a LysR-type transcriptional regulator and the second its target gene encoding a basic amino acid exporter. Whereas LysE is an exporter of arginine (Arg) and lysine (Lys) whose expression is induced by Arg, Lys, or histidine (His), ArgO exports Arg alone, and its expression is activated by Arg but not Lys or His. We have now reconstituted in E. coli the activation of lysE by LysG in the presence of its coeffectors and have shown that neither ArgP nor LysG can regulate expression of the noncognate orthologous target. Of several ArgP-dominant (ArgP(d)) variants that confer elevated Arg-independent argO expression, some (ArgP(d)-P274S, -S94L, and, to a lesser extent, -P108S) activated lysE expression in E. coli. However, the individual activating effects of LysG and ArgP(d) on lysE were mutually extinguished when both proteins were coexpressed in Arg- or His-supplemented cultures. In comparison with native ArgP, the active ArgP(d) variants exhibited higher affinity of binding to the lysE regulatory region and less DNA bending at both argO and lysE. We conclude that the transcription factor LysG from a Gram-positive bacterium, C. glutamicum, is able to engage appropriately with the RNA polymerase from a Gram-negative bacterium, E. coli, for activation of its cognate target lysE in vivo and that single-amino-acid-substitution variants of ArgP can also activate the distantly orthologous target lysE, but by a subtly different mechanism that renders them noninterchangeable with LysG. PMID:22904281

  11. Isolation and phylogenetic analysis of bacteria with antimicrobial activities from the Mediterranean sponges Aplysina aerophoba and Aplysina cavernicola.

    PubMed

    Hentschel, U; Schmid, M; Wagner, M; Fieseler, L; Gernert, C; Hacker, J

    2001-05-01

    The aim of this study was to isolate bacteria with antimicrobial activities from the marine sponges Aplysina aerophoba and Aplysina cavernicola. The obtained 27 isolates could be subdivided into eight phylogenetically different clusters based on comparative sequence analysis of their 16S rDNA genes. The sponge isolates were affiliated with the low (Bacillus) and high G+C Gram-positive bacteria (Arthobacter, Micrococcus), as well as the alpha-Proteobacteria (unknown isolate) and gamma-Proteobacteria (Vibrio, Pseudoalteromonas). One novel Bacillus species was identified and two species were closely related to previously uncharacterized strains. Isolates with antimicrobial activity were numerically most abundant in the genera Pseudoalteromonas and the alpha-Proteobacteria. The sponge isolates show antimicrobial activities against Gram-positive and Gram-negative reference strains but not against the fungus Candida albicans. A general pattern was observed in that Gram-positive bacteria inhibited Gram-positive strains while Gram-negative bacteria inhibited Gram-negative isolates. Antimicrobial activities were also found against clinical isolates, i.e. multi-resistant Staphylococcus aureus and Staphylococcus epidermidis strains isolated from hospital patients. The high recovery of strains with antimicrobial activity suggests that marine sponges represent an ecological niche which harbors a hitherto largely uncharacterized microbial diversity and, concomitantly, a yet untapped metabolic potential. PMID:11311441

  12. Robinsonia peoriae Gen. Nov., Sp. Nov., Isolated from a Swine-manure Storage Pit and a Human Clinical Source

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A polyphasic taxonomic study was performed on six strains of an unknown Gram-positive non-motile, spore-forming, short oval to rod-shaped bacterium isolated from a swine-manure storage pit. In addition to these strains, an isolate deposited in the Culture Collection, University of Goteborg (CCUG), ...

  13. Antibacterial properties of compounds isolated from Carpobrotus edulis.

    PubMed

    Martins, A; Vasas, A; Viveiros, M; Molnár, J; Hohmann, J; Amaral, L

    2011-05-01

    Several compounds isolated from the plant Carpobrotus edulis were evaluated for their activity against multidrug-resistant (MDR) bacteria and their efflux pump systems. Amongst the compounds isolated, six compounds were tested, namely uvaol, β-amyrin, oleanolic acid, catechin, epicatechin and monogalactosyldiacylglycerol. Oleanolic acid presented high antibacterial activity against a large number of bacterial strains. The triterpene uvaol was the most active compound for modulation of efflux activity by MDR Gram-positive strains. PMID:21411294

  14. Studies on a new antibiotic SF-2330. I. Taxonomy, isolation and characterization.

    PubMed

    Itoh, J; Shomura, T; Tsuyuki, T; Yoshida, J; Ito, M; Sezaki, M; Kojima, M

    1986-06-01

    A new antibiotic SF-2330 active against Gram-positive bacteria has been isolated from the culture broth of Streptomyces sp. SF-2330. The antibiotic was obtained as orange needle crystals and its molecular formula was C22H14O7. This is a new member of the pluramycin group antibiotics. PMID:3733525

  15. Genome Sequences of Three Spore-Forming Bacteria Isolated from the Feces of Organically Raised Chickens.

    PubMed

    Kennedy, Victoria; Van Laar, Tricia A; Aleru, Omoshola; Thomas, Michael; Ganci, Michelle; Rawat, Mamta

    2016-01-01

    Antibiotic feed supplements have been implicated in the rise of multidrug-resistant bacteria. An alternative to antibiotics is probiotics. Here, we report the genome sequences of two Bacillus and one Solibacillus species, all spore-forming, Gram-positive bacteria, isolated from the feces organically raised chicken feces, with potential to serve as probiotics. PMID:27587809

  16. VAGOCOCCUS ELONGATUS SP. NOV., ISOLATED FROM A SWINE-MANURE STORAGE PIT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A polyphasic taxonomic study was performed on an uncharacterized Gram-positive catalase-negative, elongated coccus-shaped bacterium isolated from a swine-manure storage pit. The bacterium, designated strain PPC9**T, was facultatively anaerobic and had a DNA G+C content of 44.5 mol%. Comparative 16...

  17. PHYSIOLOGICAL ECOLOGY OF CLOSTRIDIUM GLYCOLICUM RD-1, AN AEROTOLERANT ACETOGEN ISOLATED FROM SEA GRASS ROOTS

    EPA Science Inventory

    An anaerobic, H2-utilizing bacterium, strain RD-1, was isolated from the highest growth-positive dilution series of a root homogenate prepared from the sea grass Halodule wrightii. Cells of RD-1 were gram-positive, spore-forming, motile rods that were linked by connecting filamen...

  18. Genome Sequences of Three Spore-Forming Bacteria Isolated from the Feces of Organically Raised Chickens

    PubMed Central

    Kennedy, Victoria; Van Laar, Tricia A.; Aleru, Omoshola; Thomas, Michael; Ganci, Michelle

    2016-01-01

    Antibiotic feed supplements have been implicated in the rise of multidrug-resistant bacteria. An alternative to antibiotics is probiotics. Here, we report the genome sequences of two Bacillus and one Solibacillus species, all spore-forming, Gram-positive bacteria, isolated from the feces organically raised chicken feces, with potential to serve as probiotics. PMID:27587809

  19. Draft Genome Sequence of Bacillus megaterium BHG1.1, a Strain Isolated from Bar-Headed Goose (Anser indicus) Feces on the Qinghai-Tibet Plateau.

    PubMed

    Wang, Wen; Zheng, Si-Si; Sun, Hao; Cao, Jian; Yang, Fang; Wang, Xue-Lian; Li, Lai-Xing

    2016-01-01

    Bacillus megaterium is a soil-inhabiting Gram-positive bacterium that is routinely used in industrial applications for recombinant protein production and bioremediation. Studies involving Bacillus megaterium isolated from waterfowl are scarce. Here, we report a 6.26-Mbp draft genome sequence of Bacillus megaterium BHG1.1, which was isolated from feces of a bar-headed goose. PMID:27174262

  20. Draft Genome Sequence of Bacillus megaterium BHG1.1, a Strain Isolated from Bar-Headed Goose (Anser indicus) Feces on the Qinghai-Tibet Plateau

    PubMed Central

    Wang, Wen; Zheng, Si-Si; Sun, Hao; Cao, Jian; Yang, Fang; Wang, Xue-Lian

    2016-01-01

    Bacillus megaterium is a soil-inhabiting Gram-positive bacterium that is routinely used in industrial applications for recombinant protein production and bioremediation. Studies involving Bacillus megaterium isolated from waterfowl are scarce. Here, we report a 6.26-Mbp draft genome sequence of Bacillus megaterium BHG1.1, which was isolated from feces of a bar-headed goose. PMID:27174262

  1. [Directed isolation of gram-negative asporogenous bacteria from natural substrates].

    PubMed

    Ivanitskaia, L P; Singal, E M; Bodunkova, L E; Ostanina, L N; Baturina, M V

    1984-10-01

    A method for selective isolation of gramnegative nonsporulating bacteria from soil substrates was developed. The method consists of plating out the substrates on a glucose-yeast medium with addition of benzylpenicillin and nalidixic acid. The isolation frequency of gramnegative nonsporulating bacteria increased under such conditions from 9-16 (control) to 80-100 per cent. At the same time the isolation frequency of gram-positive bacteria decreased from 88.5 to 9.6 per cent. PMID:6391365

  2. Catalase-positive cocci in fermented sausage: Variability due to different pork breeds, breeding systems and sausage production technology.

    PubMed

    Iacumin, Lucilla; Manzano, Marisa; Comi, Giuseppe

    2012-04-01

    The aim of this study was to compare the ecology of catalase-positive cocci (CPC) present in traditional fermented sausages produced using different breeds of pork, each of which was raised in two different environments and processed using two different technologies. Semi-quantitative molecular methods were used to determine bacterial identities. Almost all fermentations were characterised by a significant increase in CPC during the first few days of fermentation, reaching values of 10(5)-10(6) cfu g(-1) within 3 days. Staphylococcus xylosus and Staphylococcus equorum species, which were detected over the course of fermentation, were found to be the predominant population in all the monitored fermentation. Staphylococcus haemolyticus, Staphylococcus lentus, Micrococcus luteus, Macrococcus caseolyticus and Staphylococcus succinus were also present, but their concentrations were found to vary under the different experimental conditions. Using cluster analysis, we concluded that a plant-specific CPC ecology existed. In addition, the breed of pork used for production was found to influence the presence of some CPC species. However, from this study, it was not possible to reach the same conclusion regarding the breeding system used. PMID:22202871

  3. [Susceptibility of clinically-isolated bacteria strains to respiratory quinolones and evaluation of antimicrobial agent efficacy by Monte Carlo simulation].

    PubMed

    Kosaka, Tadashi; Yamada, Yukiji; Kimura, Takeshi; Kodama, Mai; Fujitomo, Yumiko; Masaki, Nakanishi; Toshiaki, Komori; Keisuke, Shikata; Fujita, Naohisa

    2016-02-01

    Respiratory quinolones (RQs) are broad-spectrum antimicrobial agents used for the treatment of a wide variety of community-acquired and nosocomial infections. However, bacterial resistance to quinolones has been on the increase. In this study, we investigated the predicted efficacy of RQs for various strains of 9 bacterial species clinically isolated at our university hospital using the Monte Carlo simulation (MCS) method based on pharmacokinetics/pharmacodynamics modeling. In addition, the influence of the patients' renal function on the efficacy of RQs was evaluated. We surveyed antimicrobial susceptibility testing of 9 bacterial species (n = number of strains) [Streptococcus pneumoniae (n = 15), Streptococcus pyogenes (n = 14), Streptococcus agalactiae (n = 19), methicillin-susceptible Staphylococcus aureus (MSSA) (n = 24), Escherichia coli (n = 35), Haemophilus influenzae (n = 17), Klebsiella pneumoniae (n = 14), Pseudomonas aeruginosa (n = 31), and Moraxella catarrhalis (n = 11)] to 4 RQs [garenoxacin (GRNX), levofloxacin (LVFX), sitafloxacin (STFX), and moxifloxacin (MFLX)]. We found that compared with the other RQs, Gram-positive cocci was most resistant to LVFX, and that the minimum inhibitory concentration (MIC₉₀) values for S. pneumoniae, S. pyogenes, S. agalactiae, and MSSA were high (2, 16, > 16, and 8 µg/mL, respectively). In regard to Gram-negative rods, the susceptibility of E. coli to RQs was found to be decreased, with the MIC₉₀ values of GRNX, LVFX, STFX, and MFLX being > 16, 16, 1, and 16 µg/mL, respectively. MCS revealed that the target attainment rate of the area under the unbound concentration-time curve divided by the MIC₉₀ (ƒ · AUC/MIC ratio), against S. pneumoniae was 86.9-100%, but against E. coli was low (52.1-66.2%). The ƒ · AUC/MIC target attainment rate of LVFX against S. pneumoniae, S. pyogenes, and S. agalactiae tended to decrease due to increased creatinine clearance, and that of LVFX and STFX against MSSA also

  4. Mycetoma due to Pseudallescheria boydii and co-isolation of Nocardia abscessus in a patient injured in road accident.

    PubMed

    Horré, R; Schumacher, G; Marklein, G; Stratmann, H; Wardelmann, E; Gilges, S; De Hoog, G S; Schaal, K P

    2002-10-01

    We report the case of a patient who developed a mycetoma after experiencing a road accident. From surgical biopsies Pseudallescheria boydii was isolated. Subsequently, after the infection had been treated with itraconazole, a Gram-positive bacterium, identified as the newly described species Nocardia abscessus, was cultured from wound fluids. PMID:12462533

  5. Complete Genome Sequence of Cryobacterium arcticum Strain PAMC 27867, Isolated from a Sedimentary Rock Sample in Northern Victoria Land, Antarctica.

    PubMed

    Lee, Jaejin; Cho, Ahnna; Yang, Jae Young; Woo, Jusun; Lee, Hong Kum; Hong, Soon Gyu; Kim, Ok-Sun

    2016-01-01

    Cryobacterium arcticum PAMC 27867, a psychrotolerant, Gram-positive bacterium, was isolated from a sedimentary rock sample collected at Eureka Spurs in northern Victoria Land, Antarctica. Here, we report the genome sequence of C. arcticum PAMC 27867. PMID:27587812

  6. Genome Sequences for a Cluster of Human Isolates of Listeria monocytogenes Identified in South Africa in 2015

    PubMed Central

    Naicker, Preneshni; Bamford, Colleen; Shuping, Liliwe; McCarthy, Kerrigan M.; Sooka, Arvinda; Smouse, Shannon L.; Tau, Nomsa; Keddy, Karen H.

    2016-01-01

    Listeria monocytogenes is a Gram-positive bacterium with a ubiquitous presence in the environment. There is growing concern about the increasing prevalence of L. monocytogenes associated with food-borne outbreaks. Here we report genome sequences for a cluster of human isolates of L. monocytogenes identified in South Africa in 2015. PMID:27056221

  7. Complete Genome Sequence of Cryobacterium arcticum Strain PAMC 27867, Isolated from a Sedimentary Rock Sample in Northern Victoria Land, Antarctica

    PubMed Central

    Lee, Jaejin; Cho, Ahnna; Yang, Jae Young; Woo, Jusun; Lee, Hong Kum; Hong, Soon Gyu

    2016-01-01

    Cryobacterium arcticum PAMC 27867, a psychrotolerant, Gram-positive bacterium, was isolated from a sedimentary rock sample collected at Eureka Spurs in northern Victoria Land, Antarctica. Here, we report the genome sequence of C. arcticum PAMC 27867. PMID:27587812

  8. Kroppenstedtia eburnea gen. nov., sp. nov., a novel thermoactinomycete isolated by environmental screening, and emended description of the family Thermoactinomycetaceae Matsuo et al. 2006 emend. Yassin et al. 2009

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A Gram-positive, spore-forming, aerobic, filamentous bacterium, strain JFMB-ATET, was isolated in 2008 during environmental screening on a surface in grade C in a contract manufacturing organization in southern Germany. The isolate grew at temperatures of 25-50°C and at pH 5.0-8.5, forming ivory-col...

  9. Genome Sequence of the Acidophilic Ferrous Iron-Oxidizing Isolate Acidithrix ferrooxidans Strain Py-F3, the Proposed Type Strain of the Novel Actinobacterial Genus Acidithrix.

    PubMed

    Eisen, Sebastian; Poehlein, Anja; Johnson, D Barrie; Daniel, Rolf; Schlömann, Michael; Mühling, Martin

    2015-01-01

    Extremely acidophilic iron-oxidizing Gram-positive bacteria comprise species within the phyla Firmicutes and Actinobacteria. Here, we report the 4.02-Mb draft genome of Acidithrix ferrooxidans Py-F3, which was isolated from a stream draining an abandoned copper mine and proposed as the type species of a new genus of Actinobacteria. PMID:25931603

  10. Erratum to: two novel species Enterococcus lemanii sp. nov. and Enterococcus eurekensis sp. nov., isolated from a swine manure storage pit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A polyphasic taxonomic study using morphological, biochemical, chemotaxonomic, and molecular genetic methods was performed on six strains of an unknown Gram-positive, nonspore-forming, facultative anaerobic coccus-shaped bacterium isolated from a swine-manure storage pit. On the basis of 16S rRNA, R...

  11. Myrocin C, a new diterpene antitumor antibiotic from Myrothecium verrucaria. I. Taxonomy of the producing strain, fermentation, isolation and biological properties.

    PubMed

    Nakagawa, M; Hsu, Y H; Hirota, A; Shima, S; Nakayama, M

    1989-02-01

    A new diterpene antitumor antibiotic, myrocin C, has been isolated from the culture filtrate of a soil fungus, Myrothecium verrucaria strain No. 55. The antibiotic was effective against Gram-positive bacteria, fungi and yeasts, and prolonged the life span of mice bearing Ehrlich ascites carcinoma. PMID:2494145

  12. Savagea faecisuis gen. nov., sp. nov., a tylosin- and tetracycline-resistant bacterium isolated from a swine-manure storage pit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A polyphasic taxonomic study using morphological, biochemical, chemotaxonomic and molecular methods was performed on three strains of an unknown Gram-positive staining, nonspore-forming, motile aerobic rod-shaped bacterium resistant to tetracycline and tylosin isolated from a swine-manure storage pi...

  13. σECF factors of gram-positive bacteria

    PubMed Central

    Souza, Bianca Mendes; Castro, Thiago Luiz de Paula; Carvalho, Rodrigo Dias de Oliveira; Seyffert, Nubia; Silva, Artur; Miyoshi, Anderson; Azevedo, Vasco

    2014-01-01

    The survival of bacteria to different environmental conditions depends on the activation of adaptive mechanisms, which are intricately driven through gene regulation. Because transcriptional initiation is considered to be the major step in the control of bacterial genes, we discuss the characteristics and roles of the sigma factors, addressing (1) their structural, functional and phylogenetic classification; (2) how their activity is regulated; and (3) the promoters recognized by these factors. Finally, we focus on a specific group of alternative sigma factors, the so-called σECF factors, in Bacillus subtilis and some of the main species that comprise the CMNR group, providing information on the roles they play in the microorganisms’ physiology and indicating some of the genes whose transcription they regulate. PMID:24921931

  14. Conductivity and Dielectric Dispersion of Gram-Positive Bacterial Cells

    PubMed

    van der Wal A; Minor; Norde; Zehnder; Lyklema

    1997-02-01

    The conductivity of bacterial cell suspensions has been studied over a wide range of ionic strengths and is interpreted in terms of their cell wall properties. The experimental data have been analyzed after improving the high kappaa double-layer theory of Fixman, by accounting for ionic mobility in the hydrodynamically stagnant layer, i.e., in the bacterial wall. Static conductivity and dielectric dispersion measurements both show that the counterions in the porous gel-like cell wall give rise to a considerable surface conductance. From a comparison of the mobile charge with the total cell wall charge it is inferred that the mobilities of the ions in the bacterial wall are of the same order but somewhat lower than those in the bulk electrolyte solution. The occurrence of surface conductance reduces the electrophoretic mobility in electrophoresis studies. If this effect is not taken into account, the zeta-potential will be underestimated, especially at low electrolyte concentrations. PMID:9056304

  15. Antibacterial activity of diketopiperazines isolated from a marine fungus using t-butoxycarbonyl group as a simple tool for purification.

    PubMed

    El-Gendy, Bahaa El-Dien M; Rateb, Mostafa E

    2015-08-15

    Nine diketopiperazines were characterized from the culture of marine fungal isolate MR2012 which based on DNA amplification and sequencing of the fungal internal transcribed spacer (ITS) region was identified as Aspergillus fumigatus. The isolated fungal metabolites 4-12 were unambiguously identified as a series of simple and re-arranged diketopiperazines by analysis of spectroscopic data. t-Butoxycarbonyl group (BOC) derivatization was used to separate the intractable mixture of 4 and 5. When all compounds were evaluated for antimicrobial activity against gram positive bacteria, the isolated metabolites showed moderate to weak effects, while the semisynthetic derivatives 4a and 5a displayed strong activity comparable to the positive control, tetracycline against gram positive bacteria. PMID:26099531

  16. Corynebacterium marinum sp. nov. isolated from coastal sediment in Qingdao, China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A taxonomic study was performed on strain D7015T, which was isolated from coastal sediment close to a coal-fired power station in Qingdao, China. D7015T comprised Gram-positive, non-motile diphtheroid rods, which grew in 0-10 % (w/v) NaCl and 4-37°C, with optimum growth at 1% (w/v) NaCl and 30-32°C...

  17. Studies on a new antibiotic FR-900336 taxonomy, isolation and characterization.

    PubMed

    Hino, M; Kino, E; Komori, T; Kohsaka, M

    1984-04-01

    A new lipophilic antibiotic, FR-900336 was isolated from a culture of Streptomyces sioyaensis subsp. tanegashimaensis . FR-900336 is light yellow and has a molecular formula C30H30NO13C1 . The characterization by IR, UV, 1H NMR and 13C NMR spectra makes a quinone structure very probable. FR-900336 is active against Gram-positive bacteria and fungi. PMID:6547131

  18. Genome Sequence of a Clostridium neonatale Strain Isolated in a Canadian Neonatal Intensive Care Unit

    PubMed Central

    Benamar, Samia; Cassir, Nadim

    2016-01-01

    Clostridium neonatale is a Gram-positive endospore-forming obligate anaerobe first isolated from the feces of premature neonates during an intensive care unit outbreak of necrotizing enterocolitis (NEC) in a Canadian neonatal intensive care unit. Here, we announce the genome draft sequence of this bacterium. It is composed of 4,710,818 bp and contains 4,169 protein-coding genes and 80 RNA genes, including 11 rRNA genes. PMID:26798088

  19. Genome Sequence of Lentibacillus jeotgali GrbiT, Isolated from Traditional Korean Salt-Fermented Seafood

    PubMed Central

    Jung, Mi-Ja; Roh, Seong Woon; Kim, Min-Soo; Whon, Tae Woong; Bae, Jin-Woo

    2011-01-01

    Lentibacillus jeotgali GrbiT, isolated from a traditional Korean salt-fermented seafood, is a strictly aerobic, Gram-positive, nonmotile, endospore-forming, moderately halophilic bacterium belonging to the family Bacillaceae in the phylum Firmicutes. Here, the draft genome sequence of L. jeotgali GrbiT (3,775,822 bp with a G+C content of 42.5%) is reported. This is the first reported genome sequence from a Lentibacillus species. PMID:22038972

  20. Identification of bacterial isolates in neonatal sepsis and their antimicrobial susceptibility.

    PubMed

    Haque, S M; Jahan, N; Mannan, M A; Hasan, M; Begum, M; Rob, S; Akhter, M; Yasmin, S; Hasnat, S K

    2014-10-01

    A cross-sectional descriptive study was conducted in the Neonatal Intensive Care Unit (NICU) of Ad-din Medical College Hospital during the period of January to December 2011 to determine the pattern of bacterial agents causing neonatal sepsis and their susceptibility pattern to various antimicrobial agents. Blood cultures were performed on admitted newborn babies (0-28 days) to rule out sepsis. Antimicrobial susceptibility testing was done for all blood culture isolates according to the criteria of the National Committee for Clinical Laboratory Standards by disk diffusion method. Out of 1000 screened blood cultures, 87(8.7%) reported as positive and the gram positive and gram negative bacteria accounted for 21(24.1%) and 66(75.9%) respectively. The most common gram positive organisms were Coagulase Negative Staphylococcus Aureus (CONS) (18.4%) and Staphylococcus Aureus (4.6%) and gram negative organisms were Acinetobacter (34.4%), Pseudomonas (21.8%) and Klebsiella spp. (6.9%). The susceptibilities were remarkably low to Ampicillin (20%) and Cefotaxim (29.6%) for both gram positive & gram negative isolates. Gram positive group had susceptibilities of 71.1% to Gentamicin, 85.7% to Imipenem & 100% to Amikacin & Vancomycin. Gram negative isolates showed higher sensitivities to Colistin (96.9%), Piperacillin-Tazobactum (78.7%), Imipenem (74.2%), Levofloxacillin (71.2%), respectively. Gram-negative bacteria showed high level of resistance to commonly used antibiotics (Ampicillin, Ceftazidim and Cefotaxim). Gentamicin, Amikacin, Imipenem and Levofloxacin were the most effective drugs compared to others. Routine bacterial surveillance and their sensitivity patterns must be an essential component of neonatal care. PMID:25481589

  1. Bacteremia due to Leuconostoc pseudomesenteroides in a Patient with Acute Lymphoblastic Leukemia: Case Report and Review of the Literature

    PubMed Central

    Nakamura, Akiko; Fujieda, Atsushi; Katayama, Naoyuki

    2016-01-01

    Leuconostoc species are vancomycin-resistant Gram-positive cocci. Infections due to Leuconostoc species have been reported in various immunocompromised patients, but little is known about such infection in patients with hematologic malignancies. We report a case of Leuconostoc infection in a 44-year-old woman with acute lymphoblastic leukemia. The patient developed a high fever despite antimicrobial therapy with doripenem after induction chemotherapy. After an isolate from blood cultures was identified as L. pseudomesenteroides, we changed the antibiotics to piperacillin-tazobactam and gentamicin, after which the patient recovered from the infection. Physicians should be aware of Leuconostoc species as causative pathogen if they encounter Gram-positive cocci bacteremia resistant to standard antibiotics such as vancomycin and teicoplanin, especially in patients with hematologic malignancies.

  2. Antibacterial and antifungal activities of neocryptolepine, biscryptolepine and cryptoquindoline, alkaloids isolated from Cryptolepis sanguinolenta.

    PubMed

    Cimanga, K; De Bruyne, T; Pieters, L; Totte, J; Tona, L; Kambu, K; Berghe, D V; Vlietinck, A J

    1998-05-01

    From the 80% EtOH extract of Cryptolepis sanguinolenta (Lindl.) Schlechter (Periplocaeae) root bark, a cryptolepine isomer named neocryptolepine, and two dimeric alkaloids named biscryptolepine and cryptoquindoline were isolated. These compounds were tested for their putative antibacterial and antifungal activities. Results have indicated that neocryptolepine showed an antibacterial activity against Gram-positive bacteria (MIC < 100 μg/ml), but was less acive against Gram-negative bacteria. It also inhibited the growth of the yeast C. albicans. Biscryptolepine exhibited only an activity against some Gram-positive bacteria (MIC = 62.5 or 31 μg/ml) while cryptoquindoline did not shown an activity against all selected microorganisms. The antibacterial activity of neocryptolepine and biscryptolepine is bacteriostatic rather than bactericidal. No antifungal activity could be observed for all alkaloids in our test system at the highest test concentration of 100 μg/ml. PMID:23195843

  3. Antibacterial effect of imipenem in vitro against important aerobic and anaerobic strains isolated from clinical specimens.

    PubMed

    Klietmann, W; Focht, J; Nösner, K

    1987-08-01

    Imipenem is a thienamycin antibiotic of the first generation with broad antibacterial activity. It covers all gram-positive organisms (including Streptococcus faecalis) and gram-negative bacteria (including Pseudomonas aeruginosa and Serratia spp.) as well as Bacteroides fragilis and other Bacteroides species. In this comparative study the antimicrobic effect against 1020 gram-negative, 927 gram-positive and 352 anaerobic strains from fresh clinical isolates was tested and compared with that of other frequently used antibiotics. The minimum inhibitory concentrations (MIC) were determined by means of a serial dilution test with micro standard plates. Within the group of gram-negative strains, imipenem was the most active antibiotic with a MIC90 of less than or equal to 0.25 mg/l for most isolates. Imipenem shows a broad spectrum of activity against gram-negative pathogenic bacteria including Escherichia coli, Klebsiella spp., Proteus spp, Enterobacter spp., Citrobacter spp. and Serratia spp., and also covers resistant strains of Pseudomonas aeruginosa, Acinetobacter spp. and Alcaligenes faecalis. Imipenem also shows high inhibiting activity against gram-positive strains and anaerobic pathogens. PMID:3477332

  4. In vitro antimicrobial activity of gatifloxacin compared with other quinolones against clinical isolates from cancer patients.

    PubMed

    Rolston, Kenneth V I; Vaziri, Irfan; Frisbee-Hume, Susan; Streeter, Harriet; LeBlanc, Barbara

    2004-11-01

    Owing to the predominance of gram-positive pathogens in neutropenic cancer patients, newer generation quinolones with an expanded gram-positive spectrum and enhanced potency, may have a role to play for prophylaxis and/or empiric therapy in such patients. The in vitro activity of gatifloxacin was compared with that of ciprofloxacin, levofloxacin and trovafloxacin against 848 recent clinical isolates from cancer patients. Against gram-positive organisms, gatifloxacin was the most active agent tested inhibiting all Aerococcus, Listeria monocytogens, Micrococcus, Stomatococcus mucilaginous, Bacillus, and Rhodococcus equi strains at < or =2 mg/l, its designated susceptibility breakpoint. It was also very active against methicillin-susceptible staphylococci and Streptococcus spp. (including penicillin nonsusceptible Streptococcus pneumoniae and viridans streptococci). It had moderate activity against methicillin-resistant staphylococci and Enterococcus faecalis, inhibiting 68-80% of these strains at < or =2 mg/l. Gatifloxacin also had good activity against the Enterobacteriaceae (although ciprofloxacin was more potent) inhibiting >95% of isolates at < or =1 mg/l. Nonfermentative gram-negative organisms were less susceptible to all 4 agents. Gatifloxacin was very active against Acinetobacter lwoffi (MIC100 0.12 mg/l) and had moderate activity against Acinetobacter baumanii, Chryseobacterium spp., Stenotrophomonas maltophilia, Pseudomonas aeruginosa and other Pseudomonas species. Alcaligenes xylosoxidans strains were relatively resistant to all 4 agents. PMID:15523180

  5. Draft Genome Sequence of Bacillus murimartini LMG 21005T, an Alkalitolerant Bacterium Isolated from a Church Wall Mural in Germany

    PubMed Central

    Wang, Jie-ping; Liu, Guo-hong; Xiao, Rong-feng; Zheng, Xue-fang; Shi, Huai; Ge, Ci-bin

    2015-01-01

    Bacillus murimartini LMG 21005T is a Gram-positive, spore-forming, and alkalitolerant bacterium isolated from a church wall mural. Here, we report the 4.17-Mb genome sequence of B. murimartini LMG 21005T, which will accelerate the application of this alkalitolerant bacterium and provide useful information for genomic taxonomy and phylogenomics of Bacillus-like bacteria. PMID:26494676

  6. Complete Genome Sequence of Clostridium sp. Strain DL-VIII, a Novel Solventogenic Clostridium Species Isolated from Anaerobic Sludge

    PubMed Central

    Taghavi, Safiyh; Izquierdo, Javier A.

    2013-01-01

    We report the genome sequence of Clostridium sp. strain DL-VIII, a novel Gram-positive, endospore-forming, solventogenic bacterium isolated from activated anaerobic sludge of a wastewater treatment plant. Aside from a complete sol operon, the 6,477,357-bp genome of DL-VIII reveals genes for several unique enzymes with applications in lignocellulose degradation, including two phenolic acid decarboxylases. PMID:23929491

  7. Comparative In Vitro Activities of Oritavancin, Dalbavancin, and Vancomycin against Methicillin-Resistant Staphylococcus aureus Isolates in a Nondividing State.

    PubMed

    Belley, Adam; Lalonde Seguin, David; Arhin, Francis; Moeck, Greg

    2016-07-01

    Antibacterial agents that kill nondividing bacteria may be of utility in treating persistent infections. Oritavancin and dalbavancin are bactericidal lipoglycopeptides that are approved for acute bacterial skin and skin structure infections in adults caused by susceptible Gram-positive pathogens. Using time-kill methodology, we demonstrate that oritavancin exerts bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA) isolates that are maintained in a nondividing state in vitro, whereas dalbavancin and the glycopeptide vancomycin do not. PMID:27067327

  8. In vitro activity of daptomycin against clinical isolates with reduced susceptibilities to linezolid and quinupristin/dalfopristin.

    PubMed

    Anastasiou, Diane M; Thorne, Grace M; Luperchio, Steven A; Alder, Jeff D

    2006-11-01

    An initiative was taken to determine the in vitro activity of daptomycin against 85 Gram-positive isolates with reduced susceptibilities to linezolid and quinupristin/dalfopristin. Daptomycin had potent activity against all strains, with a Staphylococcus spp. minimum inhibitory concentration (MIC) < or =2 microg/mL and an Enterococcus spp. MIC < or =8 microg/mL. Resistance to linezolid and quinupristin/dalfopristin appears to be independent of reduced susceptibility to daptomycin. PMID:17046205

  9. High-quality draft genome sequence of Kocuria marina SO9-6, an actinobacterium isolated from a copper mine</