Science.gov

Sample records for streptococcus promotes resistance

  1. The IL-8 Protease SpyCEP/ScpC of Group A Streptococcus Promotes Resistance to Neutrophil Killing

    PubMed Central

    Zinkernagel, Annelies S.; Timmer, Anjuli M.; Pence, Morgan A.; Locke, Jeffrey B.; Buchanan, John T.; Turner, Claire E.; Mishalian, Inbal; Sriskandan, Shiranee; Hanski, Emanuel; Nizet, Victor

    2009-01-01

    SUMMARY Interleukin-8 (IL-8) promotes neutrophil-mediated host defense through its chemoattractant and immunostimulatory activities. The Group A Streptococcus (GAS) protease SpyCEP (also called ScpC) cleaves IL-8, and SpyCEP expression is strongly upregulated in vivo in the M1T1 GAS strains associated with life-threatening systemic disease including necrotizing fasciitis. Coupling allelic replacement with heterologous gene expression, we show that SpyCEP is necessary and sufficient for IL-8 degradation. SpyCEP decreased IL-8-dependent neutrophil endothelial transmigration and bacterial killing, the latter by reducing neutrophil extracellular trap formation. The knockout mutant lacking SpyCEP was attenuated for virulence in murine infection models, and SpyCEP expression conferred protection to coinfecting bacteria. We also show that the zoonotic pathogen Streptococcus iniae possesses a functional homolog of SpyCEP (Cepl) that cleaves IL-8, promotes neutrophil resistance, and contributes to virulence. By inactivating the multifunctional host defense peptide IL-8, the SpyCEP protease impairs neutrophil clearance mechanisms, contributing to the pathogenesis of invasive streptococcal infection. PMID:18692776

  2. Macrolide Resistance in Streptococcus pneumoniae

    PubMed Central

    Schroeder, Max R.; Stephens, David S.

    2016-01-01

    Streptococcus pneumoniae is a common commensal and an opportunistic pathogen. Suspected pneumococcal upper respiratory infections and pneumonia are often treated with macrolide antibiotics. Macrolides are bacteriostatic antibiotics and inhibit protein synthesis by binding to the 50S ribosomal subunit. The widespread use of macrolides is associated with increased macrolide resistance in S. pneumoniae, and the treatment of pneumococcal infections with macrolides may be associated with clinical failures. In S. pneumoniae, macrolide resistance is due to ribosomal dimethylation by an enzyme encoded by erm(B), efflux by a two-component efflux pump encoded by mef (E)/mel(msr(D)) and, less commonly, mutations of the ribosomal target site of macrolides. A wide array of genetic elements have emerged that facilitate macrolide resistance in S. pneumoniae; for example erm(B) is found on Tn917, while the mef (E)/mel operon is carried on the 5.4- or 5.5-kb Mega element. The macrolide resistance determinants, erm(B) and mef (E)/mel, are also found on large composite Tn916-like elements most notably Tn6002, Tn2009, and Tn2010. Introductions of 7-valent and 13-valent pneumococcal conjugate vaccines (PCV-7 and PCV-13) have decreased the incidence of macrolide-resistant invasive pneumococcal disease, but serotype replacement and emergence of macrolide resistance remain an important concern. PMID:27709102

  3. d-Alanylation of Teichoic Acids Promotes Group A Streptococcus Antimicrobial Peptide Resistance, Neutrophil Survival, and Epithelial Cell Invasion

    PubMed Central

    Kristian, Sascha A.; Datta, Vivekanand; Weidenmaier, Christopher; Kansal, Rita; Fedtke, Iris; Peschel, Andreas; Gallo, Richard L.; Nizet, Victor

    2005-01-01

    Group A streptococcus (GAS) is a leading cause of severe, invasive human infections, including necrotizing fasciitis and toxic shock syndrome. An important element of the mammalian innate defense system against invasive bacterial infections such as GAS is the production of antimicrobial peptides (AMPs) such as cathelicidins. In this study, we identify a specific GAS phenotype that confers resistance to host AMPs. Allelic replacement of the dltA gene encoding d-alanine-d-alanyl carrier protein ligase in an invasive serotype M1 GAS isolate led to loss of teichoic acid d-alanylation and an increase in net negative charge on the bacterial surface. Compared to the wild-type (WT) parent strain, the GAS ΔdltA mutant exhibited increased susceptibility to AMP and lysozyme killing and to acidic pH. While phagocytic uptake of WT and ΔdltA mutants by human neutrophils was equivalent, neutrophil-mediated killing of the ΔdltA strain was greatly accelerated. Furthermore, we observed the ΔdltA mutant to be diminished in its ability to adhere to and invade cultured human pharyngeal epithelial cells, a likely proximal step in the pathogenesis of invasive infection. Thus, teichoic acid d-alanylation may contribute in multiple ways to the propensity of invasive GAS to bypass mucosal defenses and produce systemic infection. PMID:16166534

  4. Acriflavine-Resistant Mutant of Streptococcus cremoris†

    PubMed Central

    Sinha, R.P.

    1977-01-01

    Selection for resistance to acriflavine in Streptococcus cremoris resulted in cross-resistance to the drugs neomycin, streptomycin, ethidium bromide, mitomycin C, and proflavine. Furthermore, the mutants showed resistance to lytic bacteriophages to which the parental strain was sensitive, and, unlike the parent, the mutants grew well at higher temperatures (40°C). Revertants selected independently either for temperature sensitivity or for acriflavine sensitivity lost resistance to all the drugs and dyes but retained the bacteriophage resistance phenotype. The acriflavine-resistant mutation resulted in an increase in resistance by the bacterial cells to sodium dodecyl sulfate, a potent solvent of lipopolysaccharide and lipoprotein. It is suggested that the acriflavine resistance mutation determines the synthesis of a membrane substance resistant to higher temperatures. PMID:907329

  5. Genetic Basis of Antibiotic Resistance in Clinical Isolates of Streptococcus gallolyticus (Streptococcus bovis)

    PubMed Central

    Leclercq, Roland; Huet, Corinne; Picherot, Mélanie; Trieu-Cuot, Patrick; Poyart, Claire

    2005-01-01

    Among 128 Streptococcus gallolyticus (Streptococcus bovis) isolates, 77.7% were resistant to tetracyclines and contained tet(M) and/or tet(L) and/or tet(O). A total of 59.4% had macrolide resistance and contained erm(B) and, rarely, mef(A). Among the one-third of isolates highly resistant to kanamycin and streptomycin, most harbored aphA3 and aad-6 genes. PMID:15793162

  6. Fluoroquinolone Resistance in Penicillin-resistant Streptococcus pneumoniae Clones, Spain

    PubMed Central

    Balsalobre, Luz; Ardanuy, Carmen; Fenoll, Asunción; Pérez-Trallero, Emilio; Liñares, Josefina

    2004-01-01

    Among 2,882 Streptococcus pneumoniae sent to the Spanish Reference Laboratory during 2002, 75 (2.6%) were ciprofloxacin-resistant. Resistance was associated with older patients (3.9% in adults and 7.2% in patients >65 years of age), with isolation from noninvasive sites (4.3% vs. 1.0%), and with penicillin and macrolide resistance. Among 14 low-level resistant (MIC 4–8 µg/mL) strains, 1 had a fluoroquinolone efflux phenotype, and 13 showed single ParC changes. The 61 high-level ciprofloxacin-resistant (MIC >16 µg/mL) strains showed either two or three changes at ParC, ParE, and GyrA. Resistance was acquired either by point mutation (70 strains) or by recombination with viridans streptococci (4 strains) at the topoisomerase II genes. Although 36 pulsed-field gel electrophoresis patterns were observed, 5 international multiresistant clones (Spain23F-1, Spain6B-2, Spain9V-3, Spain14-5 and Sweden15A-25) accounted for 35 (46.7%) of the ciprofloxacin-resistant strains. Continuous surveillance is needed to prevent the dissemination of these clones. PMID:15504260

  7. Fluoroquinolone resistance in penicillin-resistant Streptococcus pneumoniae clones, Spain.

    PubMed

    de la Campa, Adela G; Balsalobre, Luz; Ardanuy, Carmen; Fenoll, Asunción; Pérez-Trallero, Emilio; Liñares, Josefina

    2004-10-01

    Among 2,882 Streptococcus pneumoniae sent to the Spanish Reference Laboratory during 2002, 75 (2.6%) were ciprofloxacin-resistant. Resistance was associated with older patients (3.9% in adults and 7.2% in patients > or =65 years of age), with isolation from noninvasive sites (4.3% vs. 1.0%), and with penicillin and macrolide resistance. Among 14 low-level resistant (MIC 4-8 microg/mL) strains, 1 had a fluoroquinolone efflux phenotype, and 13 showed single ParC changes. The 61 high-level ciprofloxacin-resistant (MIC > or =16 microg/mL) strains showed either two or three changes at ParC, ParE, and GyrA. Resistance was acquired either by point mutation (70 strains) or by recombination with viridans streptococci (4 strains) at the topoisomerase II genes. Although 36 pulsed-field gel electrophoresis patterns were observed, 5 international multiresistant clones (Spain23F-1, Spain6B-2, Spain9V-3, Spain14-5 and Sweden15A-25) accounted for 35 (46.7%) of the ciprofloxacin-resistant strains. Continuous surveillance is needed to prevent the dissemination of these clones.

  8. Fluoroquinolone Resistance among Clonal Complex 1 Group B Streptococcus Strains

    PubMed Central

    Teatero, Sarah; Patel, Samir N.

    2016-01-01

    Fluoroquinolone resistance in group B Streptococcus is increasingly being reported worldwide. Here, we correlated fluoroquinolone resistance with mutations in gyrA, gyrB, parC, and parE genes, identified by mining whole-genome sequencing (WGS) data of 190 clonal complex 1 group B Streptococcus strains recovered from patients with invasive diseases in North America. We report a high prevalence of fluoroquinolone resistance (12%) among GBS strains in our collection. Our approach is the first step towards accurate prediction of fluoroquinolone resistance from WGS data in this opportunistic pathogen. PMID:27559344

  9. Bacteremic pneumonia caused by extensively drug-resistant Streptococcus pneumoniae.

    PubMed

    Kang, Cheol-In; Baek, Jin Yang; Jeon, Kyeongman; Kim, So Hyun; Chung, Doo Ryeon; Peck, Kyong Ran; Lee, Nam Yong; Song, Jae-Hoon

    2012-12-01

    The emergence of antimicrobial resistance threatens the successful treatment of pneumococcal infections. Here we report a case of bacteremic pneumonia caused by an extremely drug-resistant strain of Streptococcus pneumoniae, nonsusceptible to at least one agent in all classes but vancomycin and linezolid, posing an important new public health threat in our region.

  10. Antimicrobial Drug Use and Macrolide-Resistant Streptococcus pyogenes, Belgium

    PubMed Central

    Van Heirstraeten, Liesbet; Coenen, Samuel; Lammens, Christine; Hens, Niel; Goossens, Herman

    2012-01-01

    In Belgium, decreasing macrolide, lincosamide, streptogramins B, and tetracycline use during 1997–2007 correlated significantly with decreasing macrolide-resistant Streptococcus pyogenes during 1999–2009. Maintaining drug use below a critical threshold corresponded with low-level macrolide-resistant S. pyogenes and an increased number of erm(A)-harboring emm77 S. pyogenes with low fitness costs. PMID:22932671

  11. First Characterization of Fluoroquinolone Resistance in Streptococcus suis▿

    PubMed Central

    Escudero, Jose Antonio; San Millan, Alvaro; Catalan, Ana; de la Campa, Adela G.; Rivero, Estefania; Lopez, Gema; Dominguez, Lucas; Moreno, Miguel Angel; Gonzalez-Zorn, Bruno

    2007-01-01

    We have identified and sequenced the genes encoding the quinolone-resistance determining region (QRDR) of ParC and GyrA in fluoroquinolone-susceptible and -resistant Streptococcus suis clinical isolates. Resistance is the consequence of single point mutations in the QRDRs of ParC and GyrA and is not due to clonal spread of resistant strains or horizontal gene transfer with other bacteria. PMID:17116660

  12. Emerging resistant serotypes of invasive Streptococcus pneumoniae

    PubMed Central

    Elshafie, Sittana; Taj-Aldeen, Saad J

    2016-01-01

    Background Streptococcus pneumoniae is the leading cause of meningitis and sepsis. The aim of the study was to analyze the distribution, vaccine serotype coverage, and antibiotic resistance of S. pneumoniae serotypes isolated from patients with invasive diseases, after the introduction of pneumococcal 7-valent conjugated vaccine (PCV-7). Methods A total of 134 isolates were collected from blood and cerebrospinal fluid specimens at Hamad Hospital during the period from 2005 to 2009. Isolate serotyping was done using the Quellung reaction. The prevaccination period was considered before 2005. Results The most common serotypes for all age groups were 3 (12.70%), 14 (11.90%), 1 (11.90%), 19A (9.00%), 9V (5.20%), 23F (5.20%), and 19F (4.50%). Coverage rates for infant <2 years for PCV-7, the 10-valent conjugated vaccine (PCV-10), and the 13-valent conjugated vaccine (PCV-13) were 34.78%, 52.17%, and 78.26%, respectively. Coverage rates of these vaccines were 50%, 67.86%, and 75% for the 2–5 years age group; 27.12%, 40.68%, and 64.41% for the age group 6–64 years; and 25%, 33.33%, and 66.67% for the ≥65 years age group, respectively. The percentage of nonsusceptible isolates to penicillin, cefotaxime, and erythromycin were 43.86%, 16.66%, and 22.81%, respectively. Thirty-seven isolates (32.46%) were multidrug resistant (MDR) and belonged to serotypes 14, 19A, 19F, 23F, 1, 9V, 12F, 4, 6B, 3, and 15A. Compared to previous results before the introduction of PCV-7, there was a significant reduction in penicillin-nonsusceptable S. pneumoniae from 66.67% to 43.86%, and a slight insignificant reduction in erythromycin nonsusceptible strains from 27.60% to 22.8%, while there was a significant increase in cefotaxime nonsusceptible strains from 3.55% to 16.66%. Conclusion Invasive pneumococcal strains and the emergence of MDR serotypes is a global burden that must be addressed through multiple strategies, including vaccination, antibiotic stewardship, and continuous

  13. Transfer of penicillin resistance from Streptococcus oralis to Streptococcus pneumoniae identifies murE as resistance determinant.

    PubMed

    Todorova, Katya; Maurer, Patrick; Rieger, Martin; Becker, Tina; Bui, Nhat Khai; Gray, Joe; Vollmer, Waldemar; Hakenbeck, Regine

    2015-09-01

    Beta-lactam resistant clinical isolates of Streptococcus pneumoniae contain altered penicillin-binding protein (PBP) genes and occasionally an altered murM, presumably products of interspecies gene transfer. MurM and MurN are responsible for the synthesis of branched lipid II, substrate for the PBP catalyzed transpeptidation reaction. Here we used the high-level beta-lactam resistant S. oralis Uo5 as donor in transformation experiments with the sensitive laboratory strain S. pneumoniae R6 as recipient. Surprisingly, piperacillin-resistant transformants contained no alterations in PBP genes but carried murEUo5 encoding the UDP-N-acetylmuramyl tripeptide synthetase. Codons 83-183 of murEUo5 were sufficient to confer the resistance phenotype. Moreover, the promoter of murEUo5 , which drives a twofold higher expression compared to that of S. pneumoniae R6, could also confer increased resistance. Multiple independent transformations produced S. pneumoniae R6 derivatives containing murEUo5 , pbp2xUo5 , pbp1aUo5 and pbp2bUo5 , but not murMUo5 sequences; however, the resistance level of the donor strain could not be reached. S. oralis Uo5 harbors an unusual murM, and murN is absent. Accordingly, the peptidoglycan of S. oralis Uo5 contained interpeptide bridges with one L-Ala residue only. The data suggest that resistance in S. oralis Uo5 is based on a complex interplay of distinct PBPs and other enzymes involved in peptidoglycan biosynthesis.

  14. Antibiotic Selection Pressure and Resistance in Streptococcus pneumoniae and Streptococcus pyogenes

    PubMed Central

    Albrich, Werner C.; Monnet, Dominique L.

    2004-01-01

    We correlated outpatient antibiotic use with prevalence of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP), macrolide-resistant S. pneumoniae (MRSP), and macrolide-resistant S. pyogenes (MRGAS) in 20 countries. Total antibiotic use was correlated with PNSP (r = 0.75; p < 0.001), as was macrolide use with MRSP (r = 0.88; p < 0.001) and MRGAS (r = 0.71; p = 0.004). Streptococcal resistance is directly associated with antibiotic selection pressure on a national level. PMID:15109426

  15. Streptococcus pneumoniae Isolates Resistant to Telithromycin

    PubMed Central

    Rantala, M.; Haanperä-Heikkinen, M.; Lindgren, M.; Seppälä, H.; Huovinen, P.; Jalava, J.

    2006-01-01

    The telithromycin susceptibility of 210 erythromycin-resistant pneumococci was tested with the agar diffusion method. Twenty-six erm(B)-positive isolates showed heterogeneous resistance to telithromycin, which was manifested by the presence of colonies inside the inhibition zone. When these cells were cultured and tested, they showed stable, homogeneous, and high-level resistance to telithromycin. PMID:16641460

  16. Factors That Cause Trimethoprim Resistance in Streptococcus pyogenes

    PubMed Central

    Bergmann, René; van der Linden, Mark; Chhatwal, Gursharan S.

    2014-01-01

    The use of trimethoprim in treatment of Streptococcus pyogenes infections has long been discouraged because it has been widely believed that this pathogen is resistant to this antibiotic. To gain more insight into the extent and molecular basis of trimethoprim resistance in S. pyogenes, we tested isolates from India and Germany and sought the factors that conferred the resistance. Resistant isolates were identified in tests for trimethoprim or trimethoprim-sulfamethoxazole (SXT) susceptibility. Resistant isolates were screened for the known horizontally transferable trimethoprim-insensitive dihydrofolate reductase (dfr) genes dfrG, dfrF, dfrA, dfrD, and dfrK. The nucleotide sequence of the intrinsic dfr gene was determined for resistant isolates lacking the horizontally transferable genes. Based on tentative criteria, 69 out of 268 isolates (25.7%) from India were resistant to trimethoprim. Occurring in 42 of the 69 resistant isolates (60.9%), dfrF appeared more frequently than dfrG (23 isolates; 33.3%) in India. The dfrF gene was also present in a collection of SXT-resistant isolates from Germany, in which it was the only detected trimethoprim resistance factor. The dfrF gene caused resistance in 4 out of 5 trimethoprim-resistant isolates from the German collection. An amino acid substitution in the intrinsic dihydrofolate reductase known from trimethoprim-resistant Streptococcus pneumoniae conferred resistance to S. pyogenes isolates of emm type 102.2, which lacked other aforementioned dfr genes. Trimethoprim may be more useful in treatment of S. pyogenes infections than previously thought. However, the factors described herein may lead to the rapid development and spread of resistance of S. pyogenes to this antibiotic agent. PMID:24492367

  17. Novel Levofloxacin-Resistant Multidrug-Resistant Streptococcus pneumoniae Serotype 11A Isolates, South Korea

    PubMed Central

    Park, Miey; Kim, Hyun Soo; Kim, Han-Sung; Park, Ji Young; Song, Wonkeun; Cho, Hyoun Chan

    2016-01-01

    Of 608 Streptococcus pneumoniae clinical strains isolated at a hospital in South Korea during 2009–2014, sixteen (2.6%) were identified as levofloxacin resistant. The predominant serotype was 11A (9 isolates). Two novel sequence types of multidrug-resistant S. pneumoniae with serotype 11A were identified, indicating continuous diversification of resistant strains. PMID:27767906

  18. Macrolide-Resistant Streptococcus pyogenes in Norway: Population Structure and Resistance Determinants

    PubMed Central

    Littauer, P.; Caugant, D. A.; Sangvik, M.; Høiby, E. A.; Sundsfjord, A.; Simonsen, G. S.

    2006-01-01

    A 2.7% prevalence of macrolide resistance in 1,657 Norwegian clinical Streptococcus pyogenes isolates was primarily due to erm(TR) (59%) and mef(A) (20%). Four clonal complexes comprised 75% of the strains. Macrolide resistance in S. pyogenes in Norway is imported as resistant strains or locally selected in internationally disseminated susceptible clones. PMID:16641473

  19. Genomic analysis and reconstruction of cefotaxime resistance in Streptococcus pneumoniae.

    PubMed

    Fani, Fereshteh; Brotherton, Marie-Christine; Leprohon, Philippe; Ouellette, Marc

    2013-08-01

    To identify non-penicillin-binding protein (PBP) mutations contributing to resistance to the third-generation cephalosporin cefotaxime in Streptococcus pneumoniae at the genome-wide scale. The genomes of two in vitro S. pneumoniae cefotaxime-resistant isolates and of two transformants serially transformed with the genomic DNA of cefotaxime-resistant mutants were determined by next-generation sequencing. A role in cefotaxime resistance for the mutations identified was confirmed by reconstructing resistance in a cefotaxime-susceptible background. Analysis of the genome assemblies revealed mutations in genes coding for the PBPs 2x, 2a and 3, of which pbp2x was the only mutated gene common to all mutants. The transformation of altered PBP alleles into S. pneumoniae R6 confirmed the role of PBP mutations in cefotaxime resistance, but these were not sufficient to fully explain the levels of resistance. Thirty-one additional genes were found to be mutated in at least one of the four sequenced genomes. Non-PBP resistance determinants appeared to be mostly lineage specific. Mutations in spr1333, spr0981, spr1704 and spr1098, encoding a peptidoglycan N-acetylglucosamine deacetylase, a glycosyltransferase, an ABC transporter and a sortase, respectively, were implicated in resistance by transformation experiments and allowed the reconstruction of the full level of resistance observed in the parent resistant strains. This whole-genome analysis coupled to functional studies has allowed the discovery of both known and novel cefotaxime resistance genes in S. pneumoniae.

  20. Differentiation of cultured keratinocytes promotes the adherence of Streptococcus pyogenes.

    PubMed Central

    Darmstadt, G L; Fleckman, P; Jonas, M; Chi, E; Rubens, C E

    1998-01-01

    Based on a consideration of the histopathology of nonbullous impetigo that shows localization of Streptococcus pyogenes to highly differentiated, subcorneal keratinocytes, we hypothesized that adherence of an impetigo strain of S. pyogenes would be promoted by terminal differentiation of keratinocytes. An assay was developed in which S. pyogenes adhered via pilus-like projections from the cell wall to the surface of cultured human keratinocytes in a time- and inoculum-dependent manner suggestive of a receptor-mediated process. Terminal differentiation of keratinocytes was induced by increasing the calcium concentration in the growth medium, and was confirmed by morphologic analysis using electron microscopy. Adherence of S. pyogenes was three and fourfold greater to keratinocytes differentiated in 1.0 and 1.5 mM calcium, respectively, compared with undifferentiated keratinocytes in 0.15 mM calcium. The presence of calcium during the adherence assay further enhanced adherence nearly twofold. Adherence occurred preferentially to sites of contact between adjacent keratinocytes, suggesting that the keratinocyte receptor may be a molecule involved in cell-to-cell adhesion. In contrast, nonpathogenic Streptococcus gordonii adhered poorly to keratinocytes regardless of their state of terminal differentiation, and adherence of a pharyngeal strain of S. pyogenes was twofold greater to undifferentiated than differentiated keratinocytes. This is the first report of in vitro adherence of S. pyogenes to keratinocytes in a manner that emulates human impetigo. Adherence of only the impetigo strain, and not the pharyngeal strain of S. pyogenes or the nonpathogenic S. gorgonii isolate, was promoted by keratinocyte differentiation. This result provides a model system for investigating the molecular pathogenesis of streptococcal skin infections. PMID:9421474

  1. METABOLISM OF RESISTANT MUTANTS OF STREPTOCOCCUS FAECALIS IV.

    PubMed Central

    Coultas, M. Katharine; Hutchison, Dorris J.

    1962-01-01

    Coultas, M. Katharine (Sloan-Kettering Institute for Cancer Research, Rye, N.Y.) and Dorris J. Hutchison. Metabolism of resistant mutants of Streptococcus faecalis. IV. Use of a biophotometer in growth-curve studies. J. Bacteriol. 84:393–401. 1962. — Analysis of data obtained using the Bonet-Maury and Jouan biophotometer has shown it to be an accurate, automatic device for recording an entire bacterial growth curve, from which quantitative measurements of growth rate can be calculated. Growth rate values obtained in this manner agree with those obtained by conventional methods. The instrument is described in detail and reference is given to other uses of this type of photometer. The growth curves of Streptococcus faecalis ATCC 8043 and three mutants resistant to purine analogues were compared in media with and without a purine. Differences in these growth curves were evident. In the purine-deficient medium SF/AZAG, the 8-azaguanine-resistant mutant had the shortest doubling time, 61 min, followed by the two 6-mercaptopurine-resistant mutants (SF/MPcc, 72 min; SF/MP, 91 min), and finally the wild strain with a doubling time of 135 min. In the medium supplemented with xanthine, the respective doubling times were 52, 61, 68, and 68 min. Images PMID:14023399

  2. Multidrug-Resistant Streptococcus pneumoniae Isolates from Healthy Ghanaian Preschool Children.

    PubMed

    Dayie, Nicholas T K D; Arhin, Reuben E; Newman, Mercy J; Dalsgaard, Anders; Bisgaard, Magne; Frimodt-Møller, Niels; Slotved, Hans-Christian

    2015-12-01

    Streptococcus pneumoniae is the cause of high mortality among children worldwide. Antimicrobial treatment and vaccination are used to control pneumococcal infections. In Ghana, data on antimicrobial resistance and the prevalence of multidrug-resistant pneumococcal clones are scarce; hence, the aim of this study was to determine the antibiogram of S. pneumoniae recovered from Ghanaian children younger than six years of age and to what extent resistances were due to the spread of certain sero- and multilocus sequence typing (MLST) types. The susceptibility of 115 pneumococcal isolates, recovered in a previous study, to six antimicrobials was determined by disk diffusion test. Overall, 90.4% of isolates were intermediate penicillin resistant, 99.1% were trimethoprim resistant, 73.0% were tetracycline resistant, and 33.9% were sulfamethoxazole resistant. Low resistance was recorded for erythromycin (2.6%) and cefotaxime (5.2%). Overall, 72.2% of isolates were resistant to penicillin (I or R) and at least two other antimicrobials. MLST of 20 isolates showing resistance to at least four antimicrobials revealed a high diversity documented by 16 different clones, none of which had previously been associated with multidrug resistance. The resistances found may have emerged due to nonprudent antimicrobial use practices and there is a need to monitor and promote prudent antimicrobial usage in Ghana.

  3. Mechanism of resistance to macrolide-lincosamide-streptogramin antibiotics in Streptococcus thermophilus

    USDA-ARS?s Scientific Manuscript database

    Resistance to macrolide-lincosamide-streptogramin (MLS) group antibiotics in the dairy bacterium Streptococcus thermophilus (ST) is documented but the mechanism of resistance has not been elucidated. MIC values for erythromycin (Erm), azithromycin (Azm), tylosin (Tyl), spiramycin (Spm), pristinamyci...

  4. Antibiotic Resistances of Yogurt Starter Cultures Streptococcus thermophilus and Lactobacillus bulgaricus.

    PubMed

    Sozzi, T; Smiley, M B

    1980-11-01

    Twenty-nine strains of Lactobacillus bulgaricus and 15 strains of Streptococcus thermophilus were tested for resistance to 35 antimicrobial agents by using commercially available sensitivity disks. Approximately 35% of the isolates had uncharacteristic resistance patterns.

  5. Antibiotic Resistances of Yogurt Starter Cultures Streptococcus thermophilus and Lactobacillus bulgaricus

    PubMed Central

    Sozzi, Tommaso; Smiley, Martin B.

    1980-01-01

    Twenty-nine strains of Lactobacillus bulgaricus and 15 strains of Streptococcus thermophilus were tested for resistance to 35 antimicrobial agents by using commercially available sensitivity disks. Approximately 35% of the isolates had uncharacteristic resistance patterns. PMID:16345654

  6. Antibiotic-resistant Streptococcus pneumoniae. Implications for medical practice.

    PubMed Central

    Wang, E. E.; Kellner, J. D.; Arnold, S.

    1998-01-01

    OBJECTIVE: To review the definition and prevalence of antibiotic-resistant Streptococcus pneumoniae, its links with antibiotic prescribing, data on antibiotic prescribing and prescribing appropriateness, and evidence-based treatment guidelines for common respiratory tract syndromes. QUALITY OF EVIDENCE: Primary studies consist of cross-sectional surveys and case-control studies. Treatment guidelines are based on clinical trials, meta-analyses, and cohort studies. Study designs were appropriate for the specific study questions. MAIN FINDINGS: The increasing prevalence of penicillin-resistant S pneumoniae is concurrent with increasing antibiotic prescribing. Individual patients show a twofold to ninefold increase in nasopharyngeal carriage of resistant bacteria or invasion with resistant bacteria (among those who have received antibiotics in the preceding 3 months). Cross-sectional data as well as data from medicaid and drug databases attest to overprescribing of antibiotics for respiratory tract infections. Physician surveys and focus groups blame this on parental pressure for antibiotic prescriptions. However, parents in focus groups and surveys deny they pressure their physicians and indicate their main purpose for office visits is to obtain a diagnosis and to seek reassurance that their children are not seriously ill. Evidence-based guidelines suggest treatment strategies that would reduce antibiotic prescribing. CONCLUSIONS: The few antibiotics that can be used with resistant organisms are expensive and are increasingly being needed. To control the rise of antibiotic resistance, it is important to limit antibiotic overprescribing. PMID:9789668

  7. Fluoroquinolone resistance in Streptococcus pneumoniae from a university hospital, Thailand.

    PubMed

    Srifuengfung, Somporn; Tribuddharat, Chanwit; Chokephaibulkit, Kulkanya; Comerungsee, Sopita

    2010-11-01

    The most frequent markers of fluoroquinolone resistance in S. pneumoniae are chromosomal mutations in the quinolone-resistance-determining regions of DNA gyrase and topoisomerase IV encoding for the gyrA, gyrB and parC, parE genes. In 2008, 6.5% of the Streptococcus pneumoniae isolates in a Bangkok university hospital were resistant to ofloxacin. Using PCR and DNA sequencing, we identified mutations in both the gyrA and parC genes of four ofloxacin- and ciprofloxacin-resistant S. pneumoniae isolates (minimum inhibitory concentrations > 32 microg/ml). Mutations were found in the gyrA gene at positions Ser81Phe, Glu85Gly, Glu85Lys and in the parC gene at position Ser79Tyr. Three isolates had mutations in both genes. Two of the isolates were serotype 6B and two were serotypes not contained in currently licensed pneumococcal vaccines. This is the first report of the mechanisms of fluoroquinolone resistance in S. pneumoniae in Thailand.

  8. Mechanisms of resistance for Streptococcus pyogenes in northern Utah.

    PubMed

    Rowe, Ryan A; Stephenson, Ryan M; East, Destry L; Wright, Scott

    2009-01-01

    The purpose of this study was to (1) determine the rates of penicillin and erythromycin resistance among Streptococcus pyogenes isolates in northern Utah, and (2) determine the genotype of the erythromycin resistant strains, thereby providing information regarding the mechanism of the resistance. Seven hundred thirty-nine isolates of S. pyogenes were identified on 5% Sheep Blood Agar. Susceptibility to erythromycin and penicillin was performed using Muller-Hinton blood agar. All isolates resistant to erythromycin were then genotyped using PCR primers specific to one of the following: mefA gene, indicating the mechanism of resistance was an efflux pump; ermA gene, in which the mechanism was inducible methylation of the ribosomes; and ermB indicating constitutive methylation of the ribosomes. This study was conducted at Weber State University, in the Department of Clinical Laboratory Sciences. Samples were collected from 9 clinics ranging from North Ogden to Taylorsville, Utah. All samples were previously tested positive for S. pyogenes by the clinic from where the samples were collected. Of the 739 S. pyogenes isolates tested, 2.4% were resistant to erythromycin with no resistance observed to penicillin. Of the strains that displayed some degree of resistance, the gene frequencies observed were as follows: 48.1% mefA, 26.0% ermA, 3.7% ermB, and 22.2% multiple genes. The most common genotype was mefA, indicating that the efflux pump (M phenotype) is the most common mechanism in the surveyed area, followed by ermA, which produces the inducible methylating enzyme. A significant number of isolates was also observed to express both the efflux pump and the constitutive methylating enzyme.

  9. National Department of Defense Surveillance for Invasive Streptococcus Pneumoniae: Antibiotic Resistance, Serotype Distribution, and Arbitrarily Primed Polymerase Chain Reaction Analyses

    DTIC Science & Technology

    2008-02-15

    penicillin -susceptible and peni- cillin-resistant Streptococcnspneuttmoniae serotypes in Canada. J Infect Dis Streptococcus pneumoniae Surveillance Group...Gray for the Streptococcus pneumonia Surveillance Group Report No. 00-44 Approved for public release; distribution unlimited. NAVAL HEALTH RESEARCH...Defense Surveillance for Invasive Streptococcus pneumoniae : Antibiotic Resistance, Serotype Distribution, and Arbitrarily Primed Polymerase Chain

  10. NAD+-Glycohydrolase Promotes Intracellular Survival of Group A Streptococcus

    PubMed Central

    Sharma, Onkar; O’Seaghdha, Maghnus; Velarde, Jorge J.; Wessels, Michael R.

    2016-01-01

    A global increase in invasive infections due to group A Streptococcus (S. pyogenes or GAS) has been observed since the 1980s, associated with emergence of a clonal group of strains of the M1T1 serotype. Among other virulence attributes, the M1T1 clone secretes NAD+-glycohydrolase (NADase). When GAS binds to epithelial cells in vitro, NADase is translocated into the cytosol in a process mediated by streptolysin O (SLO), and expression of these two toxins is associated with enhanced GAS intracellular survival. Because SLO is required for NADase translocation, it has been difficult to distinguish pathogenic effects of NADase from those of SLO. To resolve the effects of the two proteins, we made use of anthrax toxin as an alternative means to deliver NADase to host cells, independently of SLO. We developed a novel method for purification of enzymatically active NADase fused to an amino-terminal fragment of anthrax toxin lethal factor (LFn-NADase) that exploits the avid, reversible binding of NADase to its endogenous inhibitor. LFn-NADase was translocated across a synthetic lipid bilayer in vitro in the presence of anthrax toxin protective antigen in a pH-dependent manner. Exposure of human oropharyngeal keratinocytes to LFn-NADase in the presence of protective antigen resulted in cytosolic delivery of NADase activity, inhibition of protein synthesis, and cell death, whereas a similar construct of an enzymatically inactive point mutant had no effect. Anthrax toxin-mediated delivery of NADase in an amount comparable to that observed during in vitro infection with live GAS rescued the defective intracellular survival of NADase-deficient GAS and increased the survival of SLO-deficient GAS. Confocal microscopy demonstrated that delivery of LFn-NADase prevented intracellular trafficking of NADase-deficient GAS to lysosomes. We conclude that NADase mediates cytotoxicity and promotes intracellular survival of GAS in host cells. PMID:26938870

  11. Loss of erythromycin resistance genes from strains of Streptococcus pyogenes that have developed resistance to levofloxacin.

    PubMed

    Billal, Dewan Sakhawat; Hotomi, Muneki; Yan, Steve S; Fedorko, Daniel P; Shimada, Jun; Fujihara, Keiji; Yamanaka, Noboru

    2009-06-01

    In the past 2 to 3 decades, erythromycin resistance in Streptococcus pyogenes has been decreasing, whereas fluoroquinolone resistance (or reduction in its susceptibility) has been reported often. Although a shift of M-type prevalence and decreased pressure from macrolides have been suggested for the decrease in erythromycin resistance, we hypothesized that this might also be a result of increased antimicrobial pressure from fluoroquinolone use. Levofloxacin resistance for 4 erythromycin-resistant parent strains was induced in vitro. Their mutants became highly resistant to the fluoroquinolones but lost their erythromycin resistance trait. Erythromycin resistance was fully restored by transconjugation with respective parent strains with either mefA- or ermTR-mediated mechanisms.

  12. Composite mobile genetic elements disseminating macrolide resistance in Streptococcus pneumoniae

    PubMed Central

    Chancey, Scott T.; Agrawal, Sonia; Schroeder, Max R.; Farley, Monica M.; Tettelin, Hervé; Stephens, David S.

    2015-01-01

    Macrolide resistance in Streptococcus pneumoniae emerged in the U.S. and globally during the early 1990's. The RNA methylase encoded by erm(B) and the macrolide efflux genes mef(E) and mel were identified as the resistance determining factors. These genes are disseminated in the pneumococcus on mobile, often chimeric elements consisting of multiple smaller elements. To better understand the variety of elements encoding macrolide resistance and how they have evolved in the pre- and post-conjugate vaccine eras, the genomes of 121 invasive and ten carriage isolates from Atlanta from 1994 to 2011 were analyzed for mobile elements involved in the dissemination of macrolide resistance. The isolates were selected to provide broad coverage of the genetic variability of antibiotic resistant pneumococci and included 100 invasive isolates resistant to macrolides. Tn916-like elements carrying mef(E) and mel on the Macrolide Genetic Assembly (Mega) and erm(B) on the erm(B) element and Tn917 were integrated into the pneumococcal chromosome backbone and into larger Tn5253-like composite elements. The results reported here include identification of novel insertion sites for Mega and characterization of the insertion sites of Tn916-like elements in the pneumococcal chromosome and in larger composite elements. The data indicate that integration of elements by conjugation was infrequent compared to recombination. Thus, it appears that conjugative mobile elements allow the pneumococcus to acquire DNA from distantly related bacteria, but once integrated into a pneumococcal genome, transformation and recombination is the primary mechanism for transmission of novel DNA throughout the pneumococcal population. PMID:25709602

  13. Genes Involved in Bacitracin Resistance in Streptococcus mutans†

    PubMed Central

    Tsuda, Hiromasa; Yamashita, Yoshihisa; Shibata, Yukie; Nakano, Yoshio; Koga, Toshihiko

    2002-01-01

    Streptococcus mutans is resistant to bacitracin, which is a peptide antibiotic produced by certain species of Bacillus. The purpose of this study was to clarify the bacitracin resistance mechanism of S. mutans. We cloned and sequenced two S. mutans loci that are involved in bacitracin resistance. The rgp locus, which is located downstream from rmlD, contains six rgp genes (rgpA to rgpF) that are involved in rhamnose-glucose polysaccharide (RGP) synthesis in S. mutans. The inactivation of RGP synthesis in S. mutans resulted in an approximately fivefold-higher sensitivity to bacitracin relative to that observed for the wild-type strain Xc. The second bacitracin resistance locus comprised four mbr genes (mbrA, mbrB, mbrC, and mbrD) and was located immediately downstream from gtfC, which encodes the water-insoluble glucan-synthesizing enzyme. Although the bacitracin sensitivities of mutants that had defects in flanking genes were similar to that of the parental strain Xc, mutants that were defective in mbrA, mbrB, mbrC, or mbrD were about 100 to 120 times more sensitive to bacitracin than strain Xc. In addition, a mutant that was defective in all of the mbrABCD genes and rgpA was more sensitive to bacitracin than either the RGP or Mbr mutants. We conclude that RGP synthesis is related to bacitracin resistance in S. mutans and that the mbr genes modulate resistance to bacitracin via an unknown mechanism that is independent of RGP synthesis. PMID:12435673

  14. Penicillin resistance and serotyping of Streptococcus pneumoniae in Latin America.

    PubMed

    Camargos, Paulo; Fischer, Gilberto Bueno; Mocelin, Helena; Dias, Cícero; Ruvinsky, Raúl

    2006-09-01

    Streptococcus pneumoniae (Strep. pneumoniae) is the main cause of bacterial pneumonia in children less than 5 years of age, with high mortality rates in developing countries. In 1993, the Regional System for Vaccines Group (SIREVA) of the pan-American Health Organisation (PAHO) began a study involving six Latin American countries to identify serotypes and their representativity in the new conjugated vaccines, and to determine the degree of resistance to penicillin. Serotypes 14 (highest resistance level), 5, 1, 6A/B, 23F, 7F, 9V, 19F, 18C, 19A, 9N, were prevalent in the region, with some differences among countries. Although resistance to penicillin ranged from 2% (Brazil) to 21.1% (Mexico), studies have shown that pneumonia caused by Strep. pneumoniae with diminished sensitivity to penillin can be treated with this antibiotic. Only 58% of the serotypes isolated in the region studied were represented in the seven-valent vaccine. Continual surveillance is essential to determine which formulation of conjugated vaccine will be suitable for use in Latin America.

  15. Drug resistance profile and serotype of streptococcus of pneumoniae infected pediatric patients.

    PubMed

    Wang, Jiefei; Huang, Nannan; Wang, Guangzhou; Yu, Fengqin

    2016-07-01

    To investigate the surveillance of drug resistance and serotype monitoring of steptococcus pneumoniae in hospitalized children. the pathogenic bacteria isolation and identification methods were employed to do the bacteria isolation identification and drug sensitive test on the specimens from Women & Infants Hospital of Zhengzhou. From the specimens, there were 134 detected strains of Streptococcus pneumoniae, and the drug resistance to erythromycin and clindamycin were respectively 97.7% and 89.9%, and the drug resistance to tetracycline, azithromycin and paediatric compound sulfamethoxazole were respectively 86. 3%, 58. 3%, 51. 2%. The vancomycin resistant Streptococcus pneumoniae were often not found. the Streptococcus pneumoniae in children were generally with drug resistant in Zhengzhou area. It shall strengthen drug resistance surveillance, and reasonably choose antibacterial agents.

  16. Streptococcus pyogenes polymyxin B-resistant mutants display enhanced ExPortal integrity.

    PubMed

    Port, Gary C; Vega, Luis A; Nylander, Andrew B; Caparon, Michael G

    2014-07-01

    The ExPortal protein secretion organelle in Streptococcus pyogenes is an anionic phospholipid-containing membrane microdomain enriched in Sec translocons and postsecretion protein biogenesis factors. Polymyxin B binds to and disrupts ExPortal integrity, resulting in defective secretion of several toxins. To gain insight into factors that influence ExPortal organization, a genetic screen was conducted to select for spontaneous polymyxin B-resistant mutants displaying enhanced ExPortal integrity. Whole-genome resequencing of 25 resistant mutants revealed from one to four mutations per mutant genome clustered primarily within a core set of 10 gene groups. Construction of mutants with individual deletions or insertions demonstrated that 7 core genes confer resistance and enhanced ExPortal integrity through loss of function, while 3 were likely due to gain of function and/or combinatorial effects. Core resistance genes include a transcriptional regulator of lipid biosynthesis, several genes involved in nutrient acquisition, and a variety of genes involved in stress responses. Two members of the latter class also function as novel regulators of the secreted SpeB cysteine protease. Analysis of the most frequently isolated mutation, a single nucleotide deletion in a track of 9 consecutive adenine residues in pstS, encoding a component of a high-affinity Pi transporter, suggests that this sequence functions as a molecular switch to facilitate stress adaptation. Together, these data suggest the existence of a membrane stress response that promotes enhanced ExPortal integrity and resistance to cationic antimicrobial peptides.

  17. Contribution of IL-1 to resistance to Streptococcus pneumoniae infection.

    PubMed

    Kafka, Daniel; Ling, Eduard; Feldman, Galia; Benharroch, Daniel; Voronov, Elena; Givon-Lavi, Noga; Iwakura, Yoichiro; Dagan, Ron; Apte, Ron N; Mizrachi-Nebenzahl, Yaffa

    2008-09-01

    The role of IL-1 in susceptibility to Streptococcus pneumoniae infection was studied in mice deficient in genes of the IL-1 family [i.e. IL-1alpha-/-, IL-1beta-/-, IL-1alpha/beta-/- and IL-1R antagonist (IL-1Ra)-/- mice] following intra-nasal inoculation. Intra-nasal inoculation of S. pneumoniae of IL-1beta-/- and IL-1alpha/beta-/- mice displayed significantly lower survival rates and higher nasopharyngeal and lung bacterial load as compared with control, IL-1alpha-/- and IL-1Ra-/- mice. Treatment of IL-1beta-/- mice with rIL-1beta significantly improved their survival. A significant increase in blood neutrophils was found in control, IL-1alpha-/- and IL-1Ra-/- but not in IL-1beta-/- and IL-1alpha/beta-/- mice. Local infiltrates of neutrophils and relatively preserved organ architecture were observed in the lungs of IL-1alpha-/- and control mice. However, S. pneumoniae-infected IL-1beta-/-, IL-1alpha/beta-/- and IL-1Ra-/- mice demonstrated diffuse pneumonia and tissue damage. Altogether, all three isoforms contribute to protection against S. pneumoniae; our results point to differential role of IL-1alpha and IL-1beta in the pathogenesis and control of S. pneumoniae infection and suggest that IL-1beta has a major role in resistance to primary pneumococcal infection while the role of IL-1alpha is less important.

  18. Costs of CRISPR-Cas-mediated resistance in Streptococcus thermophilus

    PubMed Central

    Vale, Pedro F.; Lafforgue, Guillaume; Gatchitch, Francois; Gardan, Rozenn; Moineau, Sylvain; Gandon, Sylvain

    2015-01-01

    CRISPR-Cas is a form of adaptive sequence-specific immunity in microbes. This system offers unique opportunities for the study of coevolution between bacteria and their viral pathogens, bacteriophages. A full understanding of the coevolutionary dynamics of CRISPR-Cas requires knowing the magnitude of the cost of resisting infection. Here, using the gram-positive bacterium Streptococcus thermophilus and its associated virulent phage 2972, a well-established model system harbouring at least two type II functional CRISPR-Cas systems, we obtained different fitness measures based on growth assays in isolation or in pairwise competition. We measured the fitness cost associated with different components of this adaptive immune system: the cost of Cas protein expression, the constitutive cost of increasing immune memory through additional spacers, and the conditional costs of immunity during phage exposure. We found that Cas protein expression is particularly costly, as Cas-deficient mutants achieved higher competitive abilities than the wild-type strain with functional Cas proteins. Increasing immune memory by acquiring up to four phage-derived spacers was not associated with fitness costs. In addition, the activation of the CRISPR-Cas system during phage exposure induces significant but small fitness costs. Together these results suggest that the costs of the CRISPR-Cas system arise mainly due to the maintenance of the defence system. We discuss the implications of these results for the evolution of CRISPR-Cas-mediated immunity. PMID:26224708

  19. Drug Resistance Characteristics and Macrolide-Resistant Mechanisms of Streptococcus pneumoniae in Wenzhou City, China

    PubMed Central

    Hu, Dakang; Sun, Zheng; Luo, Xinhua; Liu, Shuangchun; Yu, Lianhua; Qu, Ying; Yang, Jinhong; Yu, Jian; Li, Xiangyang; Zhang, Jin

    2016-01-01

    Background Streptococcus pneumoniae (SP) is a Gram-positive, alpha-hemolytic, facultative anaerobic member of the genus Streptococcus. The erythromycin-resistant methylase (erm) gene and macrolide efflux (mef) gene are the 2 main genes that can mediate SP. Transposon (Tn) also plays an important role in the collection and metastasis of the gene. In the present study we investigated the drug resistance characteristics and the macrolide-resistant mechanisms of SP in Wenzhou City, China. Material/Methods Sixty-eight strains of SP were isolated from sputum samples of hospitalized children in the Second Affiliated Hospital of Wenzhou Medical University. These strains were analyzed using antimicrobial susceptibility tests to determine their drug resistance to 10 kinds of antibacterials. Macrolide-resistant phenotypes were identified using K-B method. PCR method was used to analyze the erm B gene, mef A gene, and int Tn gene. Results Drug resistance rates of 68 strains of SP were 98.5%, 100.0%, 63.2%, 52.9%, 94.1%, 89.7%, 0.0%, 0.0%, 16.2%, and 14.7% for clindamycin, erythromycin, penicillin G, cefotaxime, tetracycline, sulfamethoxazole/trimethoprim, levofloxacin, vancomycin, chloramphenicol, and amoxicillin, respectively. Total detection rates of the erm B gene, mef A gene, and int Tn gene were 98.5%, 91.2%, and 100.0%, respectively. Conclusions SP shows significant multi-drug resistance in Wenzhou City, whereas there is no clinical value of macrolides antibiotics for SP. cMLSB mediated by erm B gene is the most predominant phenotype among macrolide-resistant SP. The int Tn gene may play an important role in horizontal transfer and clonal dissemination of SP drug resistance genes in Wenzhou City. PMID:27483416

  20. mef(A) is the predominant macrolide resistance determinant in Streptococcus pneumoniae and Streptococcus pyogenes in Germany.

    PubMed

    Bley, Christine; van der Linden, Mark; Reinert, Ralf René

    2011-05-01

    In this study, macrolide-resistant Streptococcus pneumoniae and Streptococcus pyogenes isolates from Germany were carefully characterised by susceptibility testing, phenotyping, polymerase chain reaction (PCR) and sequencing of macrolides resistance genes, and multilocus sequence typing (MLST). Of 2045 S. pneumoniae and 352 S. pyogenes isolates, 437 (21.4%) and 29 (8.2%), respectively, were found to be macrolide-resistant. Amongst the S. pneumoniae isolates, the most prevalent resistance marker was mef(A) (57.7%) followed by erm(B) (27.0%) and mef(E) (11.2%). Of note, the dual resistance mechanism mef(E)+erm(B) was found in a relatively high proportion (4.1%) of pneumococcal isolates. Amongst the S. pyogenes isolates, 31.0% carried mef(A), 34.5% erm(B) and 13.8% erm(A). Dissemination of a single clone [mef(A)-positive England(14)-9] has significantly contributed to the emergence of macrolide resistance amongst pneumococci in Germany.

  1. Is Streptococcus pyogenes resistant or susceptible to trimethoprim-sulfamethoxazole?

    PubMed

    Bowen, Asha C; Lilliebridge, Rachael A; Tong, Steven Y C; Baird, Robert W; Ward, Peter; McDonald, Malcolm I; Currie, Bart J; Carapetis, Jonathan R

    2012-12-01

    Streptococcus pyogenes is commonly believed to be resistant to trimethoprim-sulfamethoxazole (SXT), resulting in reservations about using SXT for skin and soft tissue infections (SSTI) where S. pyogenes is involved. S. pyogenes' in vitro susceptibility to SXT depends on the medium's thymidine content. Thymidine allows S. pyogenes to bypass the sulfur-mediated inhibition of folate metabolism and, historically, has resulted in apparently reduced susceptibility of S. pyogenes to sulfur antibacterials. The low thymidine concentration in Mueller-Hinton agar (MHA) is now regulated. We explored S. pyogenes susceptibility to SXT on various media. Using two sets of 100 clinical S. pyogenes isolates, we tested for susceptibility using SXT Etests on MHA containing defibrinated horse blood and 20 mg/liter β-NAD (MHF), MHA with sheep blood (MHS), MHA alone, MHA with horse blood (MHBA), and MHA with lysed horse blood (MHLHBA). European Committee on Antibacterial Susceptibility Testing (EUCAST) breakpoints defined susceptibility (MIC, ≤ 1 mg/liter) and resistance (MIC, >2 mg/liter). In study 1, 99% of S. pyogenes isolates were susceptible to SXT on MHA, MHBA, and MHLHBA, with geometric mean MICs of 0.04, 0.04, and 0.05 mg/liter, respectively. In study 2, all 100 S. pyogenes isolates were susceptible to SXT on MHF, MHS, MHA, and MHLHBA with geometric mean MICs of 0.07, 0.16, 0.07, and 0.09 mg/liter, respectively. This study confirms the in vitro susceptibility of S. pyogenes to SXT, providing support for the use of SXT for SSTIs. A clinical trial using SXT for impetigo is ongoing.

  2. Is Streptococcus pyogenes Resistant or Susceptible to Trimethoprim-Sulfamethoxazole?

    PubMed Central

    Lilliebridge, Rachael A.; Tong, Steven Y. C.; Baird, Robert W.; Ward, Peter; McDonald, Malcolm I.; Currie, Bart J.; Carapetis, Jonathan R.

    2012-01-01

    Streptococcus pyogenes is commonly believed to be resistant to trimethoprim-sulfamethoxazole (SXT), resulting in reservations about using SXT for skin and soft tissue infections (SSTI) where S. pyogenes is involved. S. pyogenes' in vitro susceptibility to SXT depends on the medium's thymidine content. Thymidine allows S. pyogenes to bypass the sulfur-mediated inhibition of folate metabolism and, historically, has resulted in apparently reduced susceptibility of S. pyogenes to sulfur antibacterials. The low thymidine concentration in Mueller-Hinton agar (MHA) is now regulated. We explored S. pyogenes susceptibility to SXT on various media. Using two sets of 100 clinical S. pyogenes isolates, we tested for susceptibility using SXT Etests on MHA containing defibrinated horse blood and 20 mg/liter β-NAD (MHF), MHA with sheep blood (MHS), MHA alone, MHA with horse blood (MHBA), and MHA with lysed horse blood (MHLHBA). European Committee on Antibacterial Susceptibility Testing (EUCAST) breakpoints defined susceptibility (MIC, ≤1 mg/liter) and resistance (MIC, >2 mg/liter). In study 1, 99% of S. pyogenes isolates were susceptible to SXT on MHA, MHBA, and MHLHBA, with geometric mean MICs of 0.04, 0.04, and 0.05 mg/liter, respectively. In study 2, all 100 S. pyogenes isolates were susceptible to SXT on MHF, MHS, MHA, and MHLHBA with geometric mean MICs of 0.07, 0.16, 0.07, and 0.09 mg/liter, respectively. This study confirms the in vitro susceptibility of S. pyogenes to SXT, providing support for the use of SXT for SSTIs. A clinical trial using SXT for impetigo is ongoing. PMID:23052313

  3. Spring forward with improved Nile tilapia Oreochromis niloticus resistant to Streptococcus iniae and Streptococcus agalactiae IB

    USDA-ARS?s Scientific Manuscript database

    Tilapia aquaculture worldwide is valued around US $ 7 billion. Tilapia are an important source of protein for domestic (top 5 most consumed seafoods) and global food security. Two gram postitive bacteria, Streptococcus iniae and S. agalactiae, are responsible for billion dollar losses annually. Gen...

  4. Macrolide-Resistant Streptococcus pneumoniae and Streptococcus pyogenes in the Pediatric Population in Germany during 2000-2001

    PubMed Central

    Reinert, Ralf René; Lütticken, Rudolf; Bryskier, André; Al-Lahham, Adnan

    2003-01-01

    In a nationwide study in Germany covering 13 clinical microbiology laboratories, a total of 307 Streptococcus pyogenes (mainly pharyngitis) and 333 Streptococcus pneumoniae (respiratory tract infections) strains were collected from outpatients less than 16 years of age. The MICs of penicillin G, amoxicillin, cefotaxime, erythromycin A, clindamycin, levofloxacin, and telithromycin were determined by the microdilution method. In S. pyogenes isolates, resistance rates were as follows: penicillin, 0%; erythromycin A, 13.7%; and levofloxacin, 0%. Telithromycin showed good activity against S. pyogenes isolates (MIC90 = 0.25 μg/ml; MIC range, 0.016 to 16 μg/ml). Three strains were found to be telithromycin-resistant (MIC ≥ 4 μg/ml). Erythromycin-resistant strains were characterized for the underlying resistance genotype, with 40.5% having the efflux type mef(A), 38.1% having the erm(A), and 9.5% having the erm(B) genotypes. emm typing of macrolide-resistant S. pyogenes isolates showed emm types 4 (45.2%), 77 (26.2%), and 12 (11.9%) to be predominant. In S. pneumoniae, resistance rates were as follows: penicillin intermediate, 7.5%; penicillin resistant, 0%; erythromycin A, 17.4%; and levofloxacin, 0%. Telithromycin was highly active against pneumococcal isolates (MIC90 ≤ 0.016 μg/ml; range, 0.016 to 0.5 μg/ml). The overall resistance profile of streptococcal respiratory tract isolates is still favorable, but macrolide resistance is of growing concern in Germany. PMID:12543648

  5. Effects of Streptococcus pneumoniae Strain Background on Complement Resistance

    PubMed Central

    Hyams, Catherine; Opel, Sophia; Hanage, William; Yuste, Jose; Bax, Katie; Henriques-Normark, Birgitta; Spratt, Brian G.; Brown, Jeremy S.

    2011-01-01

    Background Immunity to infections caused by Streptococcus pneumoniae is dependent on complement. There are wide variations in sensitivity to complement between S. pneumoniae strains that could affect their ability to cause invasive infections. Although capsular serotype is one important factor causing differences in complement resistance between strains, there is also considerable other genetic variation between S. pneumoniae strains that may affect complement-mediated immunity. We have therefore investigated whether genetically distinct S. pneumoniae strains with the same capsular serotype vary in their sensitivity to complement mediated immunity. Methodology and Principal Findings C3b/iC3b deposition and neutrophil association were measured using flow cytometry assays for S. pneumoniae strains with different genetic backgrounds for each of eight capsular serotypes. For some capsular serotypes there was marked variation in C3b/iC3b deposition between different strains that was independent of capsule thickness and correlated closely to susceptibility to neutrophil association. C3b/iC3b deposition results also correlated weakly with the degree of IgG binding to each strain. However, the binding of C1q (the first component of the classical pathway) correlated more closely with C3b/iC3b deposition, and large differences remained in complement sensitivity between strains with the same capsular serotype in sera in which IgG had been cleaved with IdeS. Conclusions These data demonstrate that bacterial factors independent of the capsule and recognition by IgG have strong effects on the susceptibility of S. pneumoniae to complement, and could therefore potentially account for some of the differences in virulence between strains. PMID:22022358

  6. Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Isolated in Algiers, Algeria

    PubMed Central

    Ramdani-Bouguessa, Nadjia; Rahal, Kheira

    2003-01-01

    There are few data on antibiotic resistance of Streptococcus pneumoniae in Algeria. Among 309 strains, 34.6% were penicillin G-nonsusceptible S. pneumoniae strains (25.2% were intermediate and 9.4% were resistant). Serotypes 1, 5, 14, and 6 were the most frequent in invasive child infections. A multicenter study to standardize the national guidelines is needed. PMID:12543703

  7. Determining the frequency of resistance of Streptococcus pneumoniae to ciprofloxacin, levofloxacin, trovafloxacin, grepafloxacin, and gemifloxacin.

    PubMed

    Evans, M E

    2001-12-01

    Newer fluoroquinolones have good activity against Streptococcus pneunoniae and may be useful clinically for the treatment of pneumonia. Although resistance among Streptococcus pneumoniae has been reported, it is rare. The frequency of single-step resistance and the emergence of resistance were compared in serial transfer of 49 clinical isolates of penicillin-sensitive and -resistant Streptococcus pneumoniae to ciprofloxacin, levofloxacin, trovafloxacin, grepafloxacin, and gemifloxacin. Single-step resistance frequencies to four times the minimum inhibitory concentration were 2.73 x 10(-6) (+/- 8.46 x 10(-6)) for ciprofloxacin, 1.78 x 10(-7) (+/- 4.62 x 10(-7)) for trovafloxacin, 5.45 x 10(-7) (+/- 1.24 x 10(-6)) for grepafloxacin, 6.78 x 10(-7) (+/- 1.38 x 10(-6)) for gemifloxacin, and 9.23 x 10(-8) (+/- 4.47 x 10(-7)) for levofloxacin. In serial transfer experiments, all isolates became resistant to clinically relevant levels of all fluoroquinolones after eight passages. The resistance occurred most rapidly with ciprofloxacin followed by grepafloxacin, gemifloxacin, trovafloxacin, and levofloxacin. These results show that strains with decreased susceptibility to fluoroquinolones occur frequently in cultures of Streptococcus pneumoniae, and this organism can readily become resistant to clinically relevant concentrations of fluoroquinolones in vitro.

  8. Streptococcus pneumoniae: the evolution of antimicrobial resistance to beta-lactams, fluoroquinolones and macrolides.

    PubMed

    Cornick, J E; Bentley, S D

    2012-07-01

    Multi drug resistant Streptococcus pneumoniae constitute a major public health concern worldwide. In this review we discuss how the transformable nature of the pneumococcus, in parallel with antimicrobial induced stress, contributes to the evolution of antimicrobial resistance; and how the introduction of the pneumococcal conjugate vaccine has affected the situation.

  9. Complete Genome Sequence of the Attenuated Novobiocin-Resistant Streptococcus iniae Vaccine Strain ISNO

    PubMed Central

    Zhang, Dunhua; Zhang, Lee

    2014-01-01

    Streptococcus iniae ISNO is an attenuated novobiocin-resistant vaccine strain. Its full genome is 2,070,182 bp in length. The availability of this genome will allow comparative genomics to identify potential virulence genes important for pathogenesis of S. iniae and potential mechanisms associated with novobiocin resistance in this strain. PMID:24874684

  10. Identification and Functional Analysis of Genome Mutations in a Fluoride-Resistant Streptococcus mutans Strain

    PubMed Central

    Brandt, Bernd Willem; Zhu, Yuanfang; Li, Jiyao; van Loveren, Cor; Deng, Dong Mei

    2015-01-01

    It is known that fluoride-resistant microorganisms are different from fluoride-sensitive ones in growth, adherence and metabolic activity. It was hypothesized that these phenotypic differences were due to stable genotypic changes in the fluoride-resistant strains. However, until now, no studies have reported these genotypic changes. The aim of this study is to identify such changes in a fluoride-resistant Streptococcus mutans strain (C180-2FR) using whole-genome shotgun (WGS) sequencing and to examine the potential function of the identified mutations by comparing gene expression between the fluoride-sensitive (C180-2) and C180-2FR strains. We performed 50 bp paired-end Illumina shotgun sequencing for both strains. Through extensive bioinformatic analysis, we were able to identify 8 single nucleotide polymorphisms (SNPs) in the genome of C180-2FR, which were further confirmed by Sanger sequencing. Expression of the genes containing or in proximity to the SNPs in C180-2 and C180-2FR was then quantified by real-time PCR. A gene cluster containing genes coding for fluoride antiporters was up-regulated 10-fold in C180-2FR when compared to that in C180-2, independent of growth phase. Two SNPs are located in this gene cluster, one in its promoter region and the other in its protein-coding region. In addition, one gene, which codes for a putative glycerol uptake facilitator protein, was found to be down-regulated by 60% in C180-2FR at an early growth phase. The promoter region of this gene contained a SNP. No difference in expression was found for the other SNP-containing genes. In summary, using WGS sequencing, we were able to uncover genetic changes in the genome of a fluoride-resistant strain. These findings can provide new insights into the mechanism of microbial fluoride resistance. PMID:25856576

  11. Identification and functional analysis of genome mutations in a fluoride-resistant Streptococcus mutans strain.

    PubMed

    Liao, Ying; Chen, Jianwei; Brandt, Bernd Willem; Zhu, Yuanfang; Li, Jiyao; van Loveren, Cor; Deng, Dong Mei

    2015-01-01

    It is known that fluoride-resistant microorganisms are different from fluoride-sensitive ones in growth, adherence and metabolic activity. It was hypothesized that these phenotypic differences were due to stable genotypic changes in the fluoride-resistant strains. However, until now, no studies have reported these genotypic changes. The aim of this study is to identify such changes in a fluoride-resistant Streptococcus mutans strain (C180-2FR) using whole-genome shotgun (WGS) sequencing and to examine the potential function of the identified mutations by comparing gene expression between the fluoride-sensitive (C180-2) and C180-2FR strains. We performed 50 bp paired-end Illumina shotgun sequencing for both strains. Through extensive bioinformatic analysis, we were able to identify 8 single nucleotide polymorphisms (SNPs) in the genome of C180-2FR, which were further confirmed by Sanger sequencing. Expression of the genes containing or in proximity to the SNPs in C180-2 and C180-2FR was then quantified by real-time PCR. A gene cluster containing genes coding for fluoride antiporters was up-regulated 10-fold in C180-2FR when compared to that in C180-2, independent of growth phase. Two SNPs are located in this gene cluster, one in its promoter region and the other in its protein-coding region. In addition, one gene, which codes for a putative glycerol uptake facilitator protein, was found to be down-regulated by 60% in C180-2FR at an early growth phase. The promoter region of this gene contained a SNP. No difference in expression was found for the other SNP-containing genes. In summary, using WGS sequencing, we were able to uncover genetic changes in the genome of a fluoride-resistant strain. These findings can provide new insights into the mechanism of microbial fluoride resistance.

  12. Emergence of a Streptococcus pneumoniae Clinical Isolate Highly Resistant to Telithromycin and Fluoroquinolones

    PubMed Central

    Faccone, Diego; Andres, Patricia; Galas, Marcelo; Tokumoto, Marta; Rosato, Adriana; Corso, Alejandra

    2005-01-01

    Streptococcus pneumoniae is a major pathogen causing community-acquired pneumonia and acute bronchitis. Macrolides, fluoroquinolones (FQs), and, recently, telithromycin (TEL) constitute primary therapeutic options, and rare cases of resistance have been reported. In this report, we describe the emergence of an S. pneumoniae clinical isolate with high-level TEL resistance (MIC, 256 μg/ml) and simultaneous resistance to FQs. Ongoing studies are oriented to elucidate the precise mechanism of resistance to TEL. PMID:16272525

  13. Emergence of a Streptococcus pneumoniae clinical isolate highly resistant to telithromycin and fluoroquinolones.

    PubMed

    Faccone, Diego; Andres, Patricia; Galas, Marcelo; Tokumoto, Marta; Rosato, Adriana; Corso, Alejandra

    2005-11-01

    Streptococcus pneumoniae is a major pathogen causing community-acquired pneumonia and acute bronchitis. Macrolides, fluoroquinolones (FQs), and, recently, telithromycin (TEL) constitute primary therapeutic options, and rare cases of resistance have been reported. In this report, we describe the emergence of an S. pneumoniae clinical isolate with high-level TEL resistance (MIC, 256 microg/ml) and simultaneous resistance to FQs. Ongoing studies are oriented to elucidate the precise mechanism of resistance to TEL.

  14. Mucosal vaccination promotes clearance of Streptococcus agalactiae vaginal colonization.

    PubMed

    Baker, Jacqueline A; Lewis, Emma L; Byland, Leah M; Bonakdar, Maryam; Randis, Tara M; Ratner, Adam J

    2017-03-01

    Group B Streptococcus (GBS) is a leading cause of morbidity and mortality in infants, and colonization of the maternal genital tract is the primary risk factor for newborn infection. Despite the importance of mucosal colonization in GBS pathogenesis, relevant host and bacterial factors are incompletely understood. We investigated the role of humoral immunity in clearance of vaginal colonization in vivo. B-cell-deficient mice or those lacking neonatal Fc-receptor, a mediator of IgG transport to the vaginal mucosa, exhibit prolonged GBS vaginal colonization compared to wild type animals. Intranasal but not intramuscular immunization induced systemic and mucosal immune responses and decreased GBS colonization duration without altering initial colonization density. Vaccine-induced clearance of GBS was serotype-specific, suggesting a role for anti-capsule antibodies in protection. Our results support a role for humoral immunity in GBS eradication from the female genital tract and suggest that mucosal vaccination may prime colonization clearance. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  15. Streptococcus pyogenes Polymyxin B-Resistant Mutants Display Enhanced ExPortal Integrity

    PubMed Central

    Port, Gary C.; Vega, Luis A.; Nylander, Andrew B.

    2014-01-01

    The ExPortal protein secretion organelle in Streptococcus pyogenes is an anionic phospholipid-containing membrane microdomain enriched in Sec translocons and postsecretion protein biogenesis factors. Polymyxin B binds to and disrupts ExPortal integrity, resulting in defective secretion of several toxins. To gain insight into factors that influence ExPortal organization, a genetic screen was conducted to select for spontaneous polymyxin B-resistant mutants displaying enhanced ExPortal integrity. Whole-genome resequencing of 25 resistant mutants revealed from one to four mutations per mutant genome clustered primarily within a core set of 10 gene groups. Construction of mutants with individual deletions or insertions demonstrated that 7 core genes confer resistance and enhanced ExPortal integrity through loss of function, while 3 were likely due to gain of function and/or combinatorial effects. Core resistance genes include a transcriptional regulator of lipid biosynthesis, several genes involved in nutrient acquisition, and a variety of genes involved in stress responses. Two members of the latter class also function as novel regulators of the secreted SpeB cysteine protease. Analysis of the most frequently isolated mutation, a single nucleotide deletion in a track of 9 consecutive adenine residues in pstS, encoding a component of a high-affinity Pi transporter, suggests that this sequence functions as a molecular switch to facilitate stress adaptation. Together, these data suggest the existence of a membrane stress response that promotes enhanced ExPortal integrity and resistance to cationic antimicrobial peptides. PMID:24794568

  16. Streptococcus pneumoniae and Streptococcus pyogenes resistant to macrolides but sensitive to clindamycin: a common resistance pattern mediated by an efflux system.

    PubMed Central

    Sutcliffe, J; Tait-Kamradt, A; Wondrack, L

    1996-01-01

    Macrolide-resistant Streptococcus pyogenes isolates from Finland, Australia, and the United Kingdom and, more recently, Streptococcus pneumoniae and S. pyogenes strains from the United States were shown to have an unusual resistance pattern to macrolides, lincosamides, and streptogramin B antibiotics. This pattern, referred to as M resistance, consists of susceptibility to clindamycin and streptogramin B antibiotics but resistance to 14- and 15-membered macrolides. An evaluation of the macrolide-lincosamide-streptogramin B resistance phenotypes among our streptococcal strains collected from 1993 to 1995 suggested that this unusual resistance pattern is not rare. Eighty-five percent (n = 66) of the S. pneumoniae and 75% (n = 28) of the S. pyogenes strains in our collection had an M phenotype. The mechanism of M resistance was not mediated by target modification, as isolated ribosomes from a pneumococcal strain bearing the M phenotype were fully sensitive to erythromycin. Further, the presence of an erm methylase was excluded with primers specific for an erm consensus sequence. However, results of studies that determined the uptake and incorporation of radiolabeled erythromycin into cells were consistent with the presence of a macrolide efflux determinant. The putative efflux determinant in streptococci seems to be distinct from the multicomponent macrolide efflux system in coagulase-negative staphylococci. The recognition of the prevalence of the M phenotype in streptococci has implications for sensitivity testing and may have an impact on the choice of antibiotic therapy in clinical practice. PMID:8843287

  17. Streptococcus anginosus (milleri) Group Strains Isolated in Poland (1996-2012) and their Antibiotic Resistance Patterns.

    PubMed

    Obszańska, Katarzyna; Kern-Zdanowicz, Izabella; Kozińska, Aleksandra; Machura, Katarzyna; Stefaniuk, Elzbieta; Hryniewicz, Waleria; Sitkiewicz, Izabela

    2016-01-01

    Streptococcus anginosus, Streptococcus intermedius and Streptococcus constellatus form a group of related streptococcal species, namely the Streptococcus Anginosus Group (SAG). The group, previously called "milleri" had been rarely described until 1980/1990 as source of infections. Nowadays SAG bacteria are often described as pathogens causing predominantly purulent infections. The number of infections is highly underestimated, as SAG strains are often classified in the microbiology laboratory as less virulent "viridans streptococci" Epidemiological situation regarding SAG infections in Poland has been unrecognized, therefore we performed a retrospective analysis of strains isolated between 1996 and 2012. Strains suspected of belonging to SAG were re-identified using an automated biochemical approach (Vitek2) and MALDI-TOF MS. We performed first analysis of antibiotic resistance among SAG strains isolated in Poland using automated methods (Vitek2), disk diffusion tests and E-Tests. We also performed PCR detection of resistance determinants in antibiotic resistant strains. Clonal structure of analyzed strains was evaluated with PFGE and MLVF methods. All three species are difficult to distinguish using automated diagnostic methods and the same is true for automated MIC evaluation. Our analysis revealed SAG strains are rarely isolated in Poland, predominantly from purulent infections. All isolates are very diverse on the genomic level as estimated by PFGE and MLVF analyses. All analyzed strains are sensitive to penicillin, a substantial group of strains is resistant to macrolides and the majority of strains are resistant to tetracycline.

  18. mefE is necessary for the erythromycin-resistant M phenotype in Streptococcus pneumoniae.

    PubMed Central

    Tait-Kamradt, A; Clancy, J; Cronan, M; Dib-Hajj, F; Wondrack, L; Yuan, W; Sutcliffe, J

    1997-01-01

    Recently, it was shown that a significant number of erythromycin-resistant Streptococcus pneumoniae and Streptococcus pyogenes strains contain a determinant that mediates resistance via a putative efflux pump. The gene encoding the erythromycin-resistant determinant was cloned and sequenced from three strains of S. pneumoniae bearing the M phenotype (macrolide resistant but clindamycin and streptogramin B susceptible). The DNA sequences of mefE were nearly identical, with only 2-nucleotide differences between genes from any two strains. When the mefE sequences were compared to the mefA sequence from S. pyogenes, the two genes were found to be closely related (90% identity). Strains of S. pneumoniae were constructed to confirm that mefE is necessary to confer erythromycin resistance and to explore the substrate specificity of the pump; no substrates other than 14- and 15-membered macrolides were identified. PMID:9333056

  19. Characterization of Spectinomycin Resistance in Streptococcus suis Leads to Two Novel Insights into Drug Resistance Formation and Dissemination Mechanism

    PubMed Central

    Huang, Kaisong; Zhang, Qiang; Song, Yajing; Zhang, Zhewen; Zhang, Anding; Xiao, Jingfa

    2016-01-01

    Spectinomycin is an aminocyclitol antibiotic used clinically to treat a variety of infections in animals. Here, we characterized drug resistance prevalence in clinical Streptococcus suis isolates and discovered a novel resistance mechanism in which the s5 mutation (Gly26Asp) results in high spectinomycin resistance. Additionally, a novel integrative and conjugative element encompassing a multidrug resistance spw_like-aadE-lnu(B)-lsa(E) cluster and a cadmium resistance operon were identified, suggesting a possible cause for the wide dissemination of spectinomycin resistance in S. suis. PMID:27458226

  20. Resistance determinants and their association with different transposons in the antibiotic-resistant Streptococcus pneumoniae.

    PubMed

    Korona-Glowniak, Izabela; Siwiec, Radoslaw; Malm, Anna

    2015-01-01

    Multiple resistance of Streptococcus pneumoniae is generally associated with their unique recombination-mediated genetic plasticity and possessing the mobile genetic elements. The aim of our study was to detect antibiotic resistance determinants and conjugative transposons in 138 antibiotic-resistant pneumococcal strains isolated from nasopharynx of healthy young children from Lublin, Poland. These strains resistant to tetracycline and/or to chloramphenicol/erythromycin/clindamycin were tested by PCR using the specific genes as markers. The presence of Tn916 family transposons, carrying tet(M) and int/xisTn916, was observed in all of the tested strains. Tn916 was detected in 16 strains resistant only to tetracycline. Tn6002 and Tn3872-related element were found among 99 erm(B)-carrying strains (83.8% and 3.0%, resp.). Eight strains harbouring mef(E) and erm(B) genes were detected, suggesting the presence of Tn2010 and Tn2017 transposons. Among 101 chloramphenicol-resistant strains, two variants of Tn5252-related transposon were distinguished depending on the presence of int/xis5252 genes specific for cat gene-containing Tn5252 (75.2% of strains) or int Sp23FST81 gene, specific for cat-containing ICESp23FST81 element (24.8% of strains). In 6 strains Tn916-like and Tn5252-like elements formed a Tn5253-like structure. Besides clonal dissemination of resistant strains of pneumococci in the population, horizontal transfer of conjugative transposons is an important factor of the high prevalence of antibiotic resistance.

  1. Development of live attenuated Streptococcus agalactiae as potential vaccines by selecting for resistance to sparfloxacin

    USDA-ARS?s Scientific Manuscript database

    To develop attenuated bacteria as potential live vaccines, sparfloxacin was used in this study to modify 40 isolates of Streptococcus agalactiae. Majority of S. agalactiae used in this study were able to develop at least 80-fold resistance to sparfloxacin. When the virulence of the sparfloxacin-resi...

  2. Complete genome sequence of an attenuated Sparfloxacin resistant Streptococcus agalactiae strain 138spar

    USDA-ARS?s Scientific Manuscript database

    Through selection of resistance to sparfloxacin, an attenuated Streptococcus agalactiae strain 138spar was obtained from its virulent parent strain S. agalactiae 138P. The full genome of S. agalactiae 138spar is 1,838,126 bp. The availability of this genome will allow comparative genomics to identi...

  3. Characterization of tetracycline-resistant Streptococcus thermophilus isolates from Italian soft cheeses.

    PubMed

    Rizzotti, Lucia; La Gioia, Federica; Dellaglio, Franco; Torriani, Sandra

    2009-06-01

    Tetracycline-resistant Streptococcus thermophilus isolates from soft cheeses harbored the genes tet(S), tet(M), and tet(L). Molecular analysis of these genes revealed their expression, localization on plasmids or Tn916-Tn1545 family transposons, and their similarity with published sequences. The study highlights the importance of an accurate safety assessment of using S. thermophilus as a starter culture.

  4. Draft Genome Sequences of Streptococcus pneumoniae with High-Level Resistance to Respiratory Fluoroquinolones.

    PubMed

    Keness, Yoram; Bisharat, Naiel

    2016-03-31

    Streptococcus pneumoniaeis the leading cause of community-acquired pneumonia. Levofloxacin is a fluoroquinolone used for treatment of severe community-acquired pneumonia. Here, we describe the draft genome sequences ofS. pneumoniaewith emerging resistance to levofloxacin, resulting in failure of treatment of pneumococcal pneumonia.

  5. Complete genome sequence of an attenuated Sparfloxacin-resistant Streptococcus agalactiae strain 138spar

    USDA-ARS?s Scientific Manuscript database

    The complete genome of a sparfloxacin-resistant Streptococcus agalactiae vaccine strain 138spar is 1,838,126 bp in size. The genome has 1892 coding sequences and 82 RNAs. The annotation of the genome is added by the NCBI Prokaryotic Genome Annotation Pipeline. The publishing of this genome will allo...

  6. Molecular characterization of cadmium resistance in Streptococcus thermophilus strain 4134: an example of lateral gene transfer.

    PubMed

    Schirawski, Jan; Hagens, Werner; Fitzgerald, Gerald F; Van Sinderen, Douwe

    2002-11-01

    Two genes (cadC(St) and cadA(St) [subscript St represents Streptococcus thermophilus]), located on the chromosome of S. thermophilus 4134, were shown to constitute a cadmium/zinc resistance cassette. The genes seem to be organized in an operon, and their transcription is cadmium dependent in vivo. The proposed product of the cadA open reading frame (CadA(St)) is highly similar to P-type cadmium efflux ATPases, whereas the predicted protein encoded by cadC(St) (CadC(St)) shows high similarity to ArsR-type regulatory proteins. The observed homologies and G+C content of this cassette and surrounding regions suggest that this DNA was derived from Lactococcus lactis and may have been introduced relatively recently into the S. thermophilus 4134 genome by a lateral gene transfer event. The complete cassette confers cadmium and zinc resistance to both S. thermophilus and L. lactis, but expression of cadA(St) alone is sufficient to give resistance. By using electrophoretic mobility shift assays it was shown that the CadC(St) protein is a DNA binding protein that binds specifically to its own promoter region, possibly to two copies of an inverted repeat, and that this CadC(St)-DNA interaction is lost in the presence of cadmium. Using lacZ fusion constructs it was shown that the cadmium-dependent expression of CadA(St) is mediated by the negative regulator CadC(St). A model for the regulation of the expression of cadmium resistance in S. thermophilus is discussed.

  7. Molecular Characterization of Cadmium Resistance in Streptococcus thermophilus Strain 4134: an Example of Lateral Gene Transfer

    PubMed Central

    Schirawski, Jan; Hagens, Werner; Fitzgerald, Gerald F.; van Sinderen, Douwe

    2002-01-01

    Two genes (cadCSt and cadASt [subscript St represents Streptococcus thermophilus]), located on the chromosome of S. thermophilus 4134, were shown to constitute a cadmium/zinc resistance cassette. The genes seem to be organized in an operon, and their transcription is cadmium dependent in vivo. The proposed product of the cadA open reading frame (CadASt) is highly similar to P-type cadmium efflux ATPases, whereas the predicted protein encoded by cadCSt (CadCSt) shows high similarity to ArsR-type regulatory proteins. The observed homologies and G+C content of this cassette and surrounding regions suggest that this DNA was derived from Lactococcus lactis and may have been introduced relatively recently into the S. thermophilus 4134 genome by a lateral gene transfer event. The complete cassette confers cadmium and zinc resistance to both S. thermophilus and L. lactis, but expression of cadASt alone is sufficient to give resistance. By using electrophoretic mobility shift assays it was shown that the CadCSt protein is a DNA binding protein that binds specifically to its own promoter region, possibly to two copies of an inverted repeat, and that this CadCSt-DNA interaction is lost in the presence of cadmium. Using lacZ fusion constructs it was shown that the cadmium-dependent expression of CadASt is mediated by the negative regulator CadCSt. A model for the regulation of the expression of cadmium resistance in S. thermophilus is discussed. PMID:12406744

  8. Frequency of Spontaneous Resistance to Peptide Deformylase Inhibitor GSK1322322 in Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae.

    PubMed

    Min, Sharon; Ingraham, Karen; Huang, Jianzhong; McCloskey, Lynn; Rilling, Sarah; Windau, Anne; Pizzollo, Jason; Butler, Deborah; Aubart, Kelly; Miller, Linda A; Zalacain, Magdalena; Holmes, David J; O'Dwyer, Karen

    2015-08-01

    The continuous emergence of multidrug-resistant pathogenic bacteria is compromising the successful treatment of serious microbial infections. GSK1322322, a novel peptide deformylase (PDF) inhibitor, shows good in vitro antibacterial activity and has demonstrated safety and efficacy in human proof-of-concept clinical studies. In vitro studies were performed to determine the frequency of resistance (FoR) to this antimicrobial agent in major pathogens that cause respiratory tract and skin infections. Resistance to GSK1322322 occurred at high frequency through loss-of-function mutations in the formyl-methionyl transferase (FMT) protein in Staphylococcus aureus (4/4 strains) and Streptococcus pyogenes (4/4 strains) and via missense mutations in Streptococcus pneumoniae (6/21 strains), but the mutations were associated with severe in vitro and/or in vivo fitness costs. The overall FoR to GSK1322322 was very low in Haemophilus influenzae, with only one PDF mutant being identified in one of four strains. No target-based mutants were identified from S. pyogenes, and only one or no PDF mutants were isolated in three of the four S. aureus strains studied. In S. pneumoniae, PDF mutants were isolated from only six of 21 strains tested; an additional 10 strains did not yield colonies on GSK1322322-containing plates. Most of the PDF mutants characterized from those three organisms (35/37 mutants) carried mutations in residues at or in close proximity to one of three highly conserved motifs that are part of the active site of the PDF protein, with 30 of the 35 mutations occurring at position V71 (using the S. pneumoniae numbering system). Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  9. Transduction of the Streptococcus pyogenes bacteriophage Φm46.1, carrying resistance genes mef(A) and tet(O), to other Streptococcus species.

    PubMed

    Giovanetti, Eleonora; Brenciani, Andrea; Morroni, Gianluca; Tiberi, Erika; Pasquaroli, Sonia; Mingoia, Marina; Varaldo, Pietro E

    2014-01-01

    Φm46.1 - Streptococcus pyogenes bacteriophage carrying mef(A) and tet(O), respectively, encoding resistance to macrolides (M phenotype) and tetracycline - is widespread in S. pyogenes but has not been reported outside this species. Φm46.1 is transferable in vitro among S. pyogenes isolates, but no information is available about its transferability to other Streptococcus species. We thus investigated Φm46.1 for its ability to be transduced in vitro to recipients of different Streptococcus species. Transductants were obtained from recipients of Streptococcus agalactiae, Streptococcus gordonii, and Streptococcus suis. Retransfer was always achieved, and from S. suis to S. pyogenes occurred at a much greater frequency than in the opposite direction. In transductants Φm46.1 retained its functional properties, such as inducibility with mitomycin C, presence both as a prophage and as a free circular form, and transferability. The transductants shared the same Φm46.1 chromosomal integration site as the donor, at the 3' end of a conserved RNA uracil methyltransferase (rum) gene, which is an integration hotspot for a variety of genetic elements. No transfer occurred to recipients of Streptococcus pneumoniae, Streptococcus oralis, and Streptococcus salivarius, even though rum-like genes were also detected in the sequenced genomes of these species. A largely overlapping 18-bp critical sequence, where the site-specific recombination process presumably takes place, was identified in the rum genes of all recipients, including those of the species yielding no transductants. Growth assays to evaluate the fitness cost of Φm46.1 acquisition disclosed a negligible impact on S. pyogenes, S. agalactiae, and S. gordonii transductants and a noticeable fitness advantage in S. suis. The S. suis transductant also displayed marked overexpression of the autolysin-encoding gene atl.

  10. High rates of erythromycin and clindamycin resistance among OBGYN isolates of group B Streptococcus.

    PubMed

    DiPersio, Linda P; DiPersio, Joseph R

    2006-01-01

    In vitro susceptibility testing on 200 Streptococcus agalactiae strains isolated during a 4-year period from vaginal/rectal specimens demonstrated a very high resistance rate for both erythromycin (54%) and clindamycin (33%). Methylase genes erm(B) and erm(TR) and efflux genes mef(E) and mef(A) were detected. Pulsed-field gel electrophoresis showed evidence of both clonal spread and multiclonal dissemination of resistant strains. All but 3 of 200 isolates were susceptible to telithromycin.

  11. [Emergence of macrolide resistant Streptococcus pyogenes strains in pediatric patients in France].

    PubMed

    Mariani-Kurkdjian, P; Doit, C; Deforche, D; Brahimi, N; Francois, M; Van den Abbeele, T; Bingen, E

    2004-10-01

    A total of 206 recent throat isolates of Streptococcus pyogenes collected between 2002 and 2004 from children were tested for their susceptibility to penicillin, amoxycillin, erythromycin, clarythromycin and clindamycin. The erythromycin resistant isolates were further studied for their genetic mechanism of resistance by means of PCR. In all, 14.5% of the strains were erythromycin resistant and 13.5 and 1% expressed the constitutive MLS(B) and M resistance phenotypes and harbored the ermB and mef A genes respectively.

  12. Description of Two New Isolates of Streptococcus pneumoniae in Spain That Are Highly Resistant to Cefotaxime

    PubMed Central

    Ruiz, Joaquín; Sempere, Marco; Simarro, Encarnación; Fenoll, Asunción

    1998-01-01

    Two strains of Streptococcus pneumoniae isolated from sputum and bronchoalveolar samples with high-level resistance to cefotaxime (MIC = 8 to 16 μg/ml) are described. One of them, belonging to serogroup 19, was also highly resistant to penicillin (MIC = 16 μg/ml), while the other, of serogroup 14, was intermediate in its resistance to penicillin (MIC = 0.25 μg/ml). To our knowledge, these are the first two strains to be isolated in Spain with such high levels of resistance to cefotaxime. PMID:9756796

  13. Persistence and complex evolution of fluoroquinolone-resistant Streptococcus pneumoniae clone.

    PubMed

    Ben-David, Debby; Schwaber, Mitchell J; Adler, Amos; Masarwa, Samira; Edgar, Rotem; Navon-Venezia, Shiri; Schwartz, David; Porat, Nurith; Kotlovsky, Tali; Polivkin, Nikolay; Weinberg, Irina; Lazary, Avraham; Ohana, Nissim; Dagan, Ron

    2014-05-01

    Prolonged outbreaks of multidrug-resistant Streptococcus pneumoniae in health care facilities are uncommon. We found persistent transmission of a fluroquinolone-resistant S. pneumoniae clone during 2006-2011 in a post-acute care facility in Israel, despite mandatory vaccination and fluoroquinolone restriction. Capsular switch and multiple antimicrobial nonsusceptibility mutations occurred within this single clone. The persistent transmission of fluoroquinolone-resistant S. pneumoniae during a 5-year period underscores the importance of long-term care facilities as potential reservoirs of multidrug-resistant streptococci.

  14. Mechanisms of group A Streptococcus resistance to reactive oxygen species.

    PubMed

    Henningham, Anna; Döhrmann, Simon; Nizet, Victor; Cole, Jason N

    2015-07-01

    Streptococcus pyogenes, also known as group A Streptococcus (GAS), is an exclusively human Gram-positive bacterial pathogen ranked among the 'top 10' causes of infection-related deaths worldwide. GAS commonly causes benign and self-limiting epithelial infections (pharyngitis and impetigo), and less frequent severe invasive diseases (bacteremia, toxic shock syndrome and necrotizing fasciitis). Annually, GAS causes 700 million infections, including 1.8 million invasive infections with a mortality rate of 25%. In order to establish an infection, GAS must counteract the oxidative stress conditions generated by the release of reactive oxygen species (ROS) at the infection site by host immune cells such as neutrophils and monocytes. ROS are the highly reactive and toxic byproducts of oxygen metabolism, including hydrogen peroxide (H2O2), superoxide anion (O2•(-)), hydroxyl radicals (OH•) and singlet oxygen (O2*), which can damage bacterial nucleic acids, proteins and cell membranes. This review summarizes the enzymatic and regulatory mechanisms utilized by GAS to thwart ROS and survive under conditions of oxidative stress.

  15. Mechanisms of group A Streptococcus resistance to reactive oxygen species

    PubMed Central

    Henningham, Anna; Döhrmann, Simon; Nizet, Victor; Cole, Jason N.

    2015-01-01

    Streptococcus pyogenes, also known as group A Streptococcus (GAS), is an exclusively human Gram-positive bacterial pathogen ranked among the ‘top 10’ causes of infection-related deaths worldwide. GAS commonly causes benign and self-limiting epithelial infections (pharyngitis and impetigo), and less frequent severe invasive diseases (bacteremia, toxic shock syndrome and necrotizing fasciitis). Annually, GAS causes 700 million infections, including 1.8 million invasive infections with a mortality rate of 25%. In order to establish an infection, GAS must counteract the oxidative stress conditions generated by the release of reactive oxygen species (ROS) at the infection site by host immune cells such as neutrophils and monocytes. ROS are the highly reactive and toxic byproducts of oxygen metabolism, including hydrogen peroxide (H2O2), superoxide anion (O2•−), hydroxyl radicals (OH•) and singlet oxygen (O2*), which can damage bacterial nucleic acids, proteins and cell membranes. This review summarizes the enzymatic and regulatory mechanisms utilized by GAS to thwart ROS and survive under conditions of oxidative stress. PMID:25670736

  16. Fitness of Streptococcus pneumoniae Fluoroquinolone-Resistant Strains with Topoisomerase IV Recombinant Genes▿

    PubMed Central

    Balsalobre, Luz; de la Campa, Adela G.

    2008-01-01

    The low prevalence of ciprofloxacin-resistant (Cpr) Streptococcus pneumoniae isolates carrying recombinant topoisomerase IV genes could be attributed to a fitness cost imposed by the horizontal transfer, which often implies the acquisition of larger-than-normal parE-parC intergenic regions. A study of the transcription of these genes and of the fitness cost for 24 isogenic Cpr strains was performed. Six first-level transformants were obtained either with PCR products containing the parC quinolone resistance-determining regions (QRDRs) of S. pneumoniae Cpr mutants with point mutations or with a PCR product that includes parE-QRDR-ant-parC-QRDR from a Cpr Streptococcus mitis isolate. The latter yielded two strains, T6 and T11, carrying parC-QRDR and parE-QRDR-ant-parC-QRDR, respectively. These first-level transformants were used as recipients in further transformations with the gyrA-QRDR PCR products to obtain 18 second-level transformants. In addition, strain Tr7 (which contains the GyrA E85K change) was used. Reverse transcription-PCR experiments showed that parE and parC were cotranscribed in R6, T6, and T11; and a single promoter located upstream of parE was identified in R6 by primer extension. The fitness of the transformants was estimated by pairwise competition with R6 in both one-cycle and two-cycle experiments. In the one-cycle experiments, most strains carrying the GyrA E85K change showed a fitness cost; the exception was recombinant T14. In the two-cycle experiments, a fitness cost was observed in most first-level transformants carrying the ParC changes S79F, S79Y, and D83Y and the GyrA E85K change; the exceptions were recombinants T6 and T11. The results suggest that there is no impediment due to a fitness cost for the spread of recombinant Cpr S. pneumoniae isolates, since some recombinants (T6, T11, and T14) exhibited an ability to compensate for the cost. PMID:18160515

  17. Fitness of Streptococcus pneumoniae fluoroquinolone-resistant strains with topoisomerase IV recombinant genes.

    PubMed

    Balsalobre, Luz; de la Campa, Adela G

    2008-03-01

    The low prevalence of ciprofloxacin-resistant (Cp r) Streptococcus pneumoniae isolates carrying recombinant topoisomerase IV genes could be attributed to a fitness cost imposed by the horizontal transfer, which often implies the acquisition of larger-than-normal parE-parC intergenic regions. A study of the transcription of these genes and of the fitness cost for 24 isogenic Cp r strains was performed. Six first-level transformants were obtained either with PCR products containing the parC quinolone resistance-determining regions (QRDRs) of S. pneumoniae Cp r mutants with point mutations or with a PCR product that includes parE-QRDR-ant-parC-QRDR from a Cp r Streptococcus mitis isolate. The latter yielded two strains, T6 and T11, carrying parC-QRDR and parE-QRDR-ant-parC-QRDR, respectively. These first-level transformants were used as recipients in further transformations with the gyrA-QRDR PCR products to obtain 18 second-level transformants. In addition, strain Tr7 (which contains the GyrA E85K change) was used. Reverse transcription-PCR experiments showed that parE and parC were cotranscribed in R6, T6, and T11; and a single promoter located upstream of parE was identified in R6 by primer extension. The fitness of the transformants was estimated by pairwise competition with R6 in both one-cycle and two-cycle experiments. In the one-cycle experiments, most strains carrying the GyrA E85K change showed a fitness cost; the exception was recombinant T14. In the two-cycle experiments, a fitness cost was observed in most first-level transformants carrying the ParC changes S79F, S79Y, and D83Y and the GyrA E85K change; the exceptions were recombinants T6 and T11. The results suggest that there is no impediment due to a fitness cost for the spread of recombinant Cp r S. pneumoniae isolates, since some recombinants (T6, T11, and T14) exhibited an ability to compensate for the cost.

  18. Emergence of vancomycin resistance in the genus Streptococcus: characterization of a vanB transferable determinant in Streptococcus bovis.

    PubMed Central

    Poyart, C; Pierre, C; Quesne, G; Pron, B; Berche, P; Trieu-Cuot, P

    1997-01-01

    Streptococcus bovis NEM760 was isolated from a stool swab collected on admission from a patient as surveillance for vancomycin-resistant enterococci. Strain NEM760 was identified as S. bovis by conventional biochemical methods and partial sequence analysis of its 16S rRNA. This strain was resistant to a low level of vancomycin (MIC, 64 micrograms/ml) but was susceptible to teicoplanin (MIC, 1 micrograms/ml), and vancomycin induced resistance to both glycopeptides. The presence of a vanB-related gene in NEM760 was demonstrated in a PCR assay which enabled specific amplification of a 635-hp internal segment of vanB. Sequence analysis of the corresponding PCR product revealed that it was highly homologous (96% identity) to the prototype vanB sequence of Enterococcus faecalis V583. The VanB resistance of determinant of S. bovis NEM760 was transferred by conjugation to E. faecalis and Enterococcus faecium at a similar frequency of 2 x 10(-5) per donor. SmaI-digested genomic DNAs of independently obtained transconjugants of E. faecalis and E. faecium were analyzed by pulsed-field gel electrophoresis and Southern hybridization with a vanB DNA probe. The electrophoretic and hybridization patterns obtained with all transconjugants of the same species were indistinguishable and revealed vanB-containing chromosomal insertions of approximately 100 kb. These results suggest that the genes mediating VanB-type resistance in S. bovis NEM760 are part of large transferable genetic elements. The results presented in the report demonstrate for the first time the role of streptococci in the dissemination of vancomycin resistance among gram-positive bacteria. PMID:8980749

  19. Antimicrobial resistance and serotype distribution of Streptococcus pneumoniae isolates from Crete, Greece.

    PubMed

    Maraki, S; Christidou, A; Tselentis, Y

    2001-06-01

    Susceptibility to 14 antibiotics was determined for 125 clinical isolates of Streptococcus pneumoniae collected over a 3-year period in Crete, Greece. Twenty-three isolates (18.4%) showed intermediate resistance and 15 (12%) high-level resistance to penicillin. Erythromycin, chloramphenicol, tetracycline, trimethoprim-sulphamethoxazole and sparfloxacin resistance rates were 16.8, 10.4, 19.2, 24.8 and 9.6%, respectively. Multiple resistance was observed in 22 strains. Vancomycin and levofloxacin were the most active agents tested. The most prevalent serotype among penicillin-susceptible pneumococci was 14, followed by 9, 7 and 1, while among penicillin-intermediate or -resistant strains serotype 23 was predominant followed by 19 and 9. These results show that as well as a high level of penicillin resistance in this region, some strains are also resistant to other antibiotics and may show multi-drug resistance.

  20. Impact of Azithromycin Administration for Trachoma Control on the Carriage of Antibiotic-Resistant Streptococcus pneumoniae

    PubMed Central

    Batt, Sarah L.; Charalambous, Bambos M.; Solomon, Anthony W.; Knirsch, Charles; Massae, Patrick A.; Safari, Salesia; Sam, Noel E.; Everett, Dean; Mabey, David C. W.; Gillespie, Stephen H.

    2003-01-01

    Community distribution of azithromycin has an important role to play in trachoma control. Previous studies have suggested that this may increase the prevalence of macrolide-resistant Streptococcus pneumoniae. S. pneumoniae was isolated from children under 7 years of age in Rombo District, northern Tanzania, before and 2 and 6 months after community-wide administration of azithromycin. Overall carriage rates were 11, 12, and 7%, respectively. Only one macrolide-resistant isolate carrying the mef gene was obtained 6 months after azithromycin administration. This contrasted with cotrimoxazole and penicillin resistance, both of which were common (cotrimoxazole resistance, 42, 43, and 47%, and penicillin resistance, 21, 17, and 16% at baseline, 2 months, and 6 months, respectively). There was a significant association between cotrimoxazole and penicillin resistance (P < 0.0001, Fisher's exact). These data suggest that in communities where macrolide resistance is rare, azithromycin distribution for trachoma control is unlikely to increase the prevalence of resistant organisms. PMID:12936971

  1. Fluoroquinolone resistance in atypical pneumococci and oral streptococci: evidence of horizontal gene transfer of fluoroquinolone resistance determinants from Streptococcus pneumoniae.

    PubMed

    Ip, Margaret; Chau, Shirley S L; Chi, Fang; Tang, Julian; Chan, Paul K

    2007-08-01

    Atypical strains, presumed to be pneumococcus, with ciprofloxacin MICs of > or =4.0 microg/ml and unique sequence variations within the quinolone resistance-determining regions (QRDRs) of the gyrase and topoisomerase genes in comparison with the Streptococcus pneumoniae R6 strain, were examined. These strains were reidentified using phenotypic methods, including detection of optochin susceptibility, bile solubility, and agglutination by serotype-specific antisera, and genotypic methods, including detection of pneumolysin and autolysin genes by PCR, 16S rRNA sequencing, and multilocus sequence typing (MLST). The analysis based on concatenated sequences of the six MLST loci distinguished the "atypical" strains from pneumococci, and these strains clustered closely with S. mitis. However, all these strains and five of nine strains from the viridans streptococcal group possessed one to three gyrA, gyrB, parC, and parE genes whose QRDR sequences clustered with those of S. pneumoniae, providing evidence of horizontal transfer of the QRDRs of the gyrase and topoisomerase genes from pneumococci into viridans streptococci. These genes also conferred fluoroquinolone resistance to viridans streptococci. In addition, the fluoroquinolone resistance determinants of 32 well-characterized Streptococcus mitis and Streptococcus oralis strains from bacteremic patients were also compared. These strains have unique amino acid substitutions in GyrA and ParC that were distinguishable from those in fluoroquinolone-resistant pneumococci and the "atypical" isolates. Both recombinational events and de novo mutations play an important role in the development of fluoroquinolone resistance.

  2. In vitro selective antibiotic concentrations of beta-lactams for penicillin-resistant Streptococcus pneumoniae populations.

    PubMed Central

    Negri, M C; Morosini, M I; Loza, E; Baquero, F

    1994-01-01

    Therapeutic regimens containing beta-lactam antibiotics are selecting penicillin-resistant Streptococcus pneumoniae populations all over the world. The selective pressure after 4 h of exposure to different concentrations of amoxicillin, cefixime, cefuroxime, and cefotaxime for low-level or high-level penicillin-resistant S. pneumoniae was evaluated in an in vitro model with mixed populations with penicillin susceptibilities of 0.015, 0.5, 1, and 2 micrograms/ml. The antibiotic concentration selecting for low-level resistance strongly reduced the susceptible population. Increasing antibiotic concentrations tended to decrease the total proportion of penicillin-resistant bacteria because of reduced numbers of the low-level-resistant population. The antibiotic concentration selecting for high-level resistance produced fewer resistant populations, but most of the organisms selected represented high-level resistance. In general, amoxicillin was a good selector for the low-level-resistant population and a poor selector for high-level resistance; cefuroxime and cefotaxime were poor selectors for low-level resistance and better selectors than amoxicillin for high-level penicillin resistance. Cefixime was the best selector of low-level penicillin resistance. When only resistant populations were mixed, the strains with high-level resistance were selected even at low antibiotic concentrations. Determination of the effects of selective antibiotic concentrations on mixed cultures of bacteria expressing different antibiotic resistance levels may help researchers to understand the ecology and epidemiology of penicillin-resistant S. pneumoniae populations. PMID:8141563

  3. vanG Element Insertions within a Conserved Chromosomal Site Conferring Vancomycin Resistance to Streptococcus agalactiae and Streptococcus anginosus

    PubMed Central

    Srinivasan, Velusamy; Metcalf, Benjamin J.; Knipe, Kristen M.; Ouattara, Mahamoudou; McGee, Lesley; Shewmaker, Patricia L.; Glennen, Anita; Nichols, Megin; Harris, Carol; Brimmage, Mary; Ostrowsky, Belinda; Park, Connie J.; Schrag, Stephanie J.; Frace, Michael A.; Sammons, Scott A.

    2014-01-01

    ABSTRACT Three vancomycin-resistant streptococcal strains carrying vanG elements (two invasive Streptococcus agalactiae isolates [GBS-NY and GBS-NM, both serotype II and multilocus sequence type 22] and one Streptococcus anginosus [Sa]) were examined. The 45,585-bp elements found within Sa and GBS-NY were nearly identical (together designated vanG-1) and shared near-identity over an ~15-kb overlap with a previously described vanG element from Enterococcus faecalis. Unexpectedly, vanG-1 shared much less homology with the 49,321-bp vanG-2 element from GBS-NM, with widely different levels (50% to 99%) of sequence identity shared among 44 related open reading frames. Immediately adjacent to both vanG-1 and vanG-2 were 44,670-bp and 44,680-bp integrative conjugative element (ICE)-like sequences, designated ICE-r, that were nearly identical in the two group B streptococcal (GBS) strains. The dual vanG and ICE-r elements from both GBS strains were inserted at the same position, between bases 1328 and 1329, within the identical RNA methyltransferase (rumA) genes. A GenBank search revealed that although most GBS strains contained insertions within this specific site, only sequence type 22 (ST22) GBS strains contained highly related ICE-r derivatives. The vanG-1 element in Sa was also inserted within this position corresponding to its rumA homolog adjacent to an ICE-r derivative. vanG-1 insertions were previously reported within the same relative position in the E. faecalis rumA homolog. An ICE-r sequence perfectly conserved with respect to its counterpart in GBS-NY was apparent within the same site of the rumA homolog of a Streptococcus dysgalactiae subsp. equisimilis strain. Additionally, homologous vanG-like elements within the conserved rumA target site were evident in Roseburia intestinalis. PMID:25053786

  4. A Novel Erythromycin Resistance Methylase Gene (ermTR) in Streptococcus pyogenes

    PubMed Central

    Seppälä, Helena; Skurnik, Mikael; Soini, Hanna; Roberts, Marilyn C.; Huovinen, Pentti

    1998-01-01

    Erythromycin resistance among streptococci is commonly due to target site modification by an rRNA-methylating enzyme, which results in coresistance to macrolide, lincosamide, and streptogramin B antibiotics (MLSB resistance). Genes belonging to the ermAM (ermB) gene class are the only erythromycin resistance methylase (erm) genes in Streptococcus pyogenes with MLSB resistance that have been sequenced so far. We identified a novel erm gene, designated ermTR, from an erythromycin-resistant clinical strain of S. pyogenes (strain A200) with an inducible type of MLSB resistance. The nucleotide sequence of ermTR is 82.5% identical to ermA, previously found, for example, in Staphylococcus aureus and coagulase-negative staphylococci. Our finding provides the first sequence of an erm gene other than ermAM that mediates MLSB resistance in S. pyogenes. PMID:9527769

  5. Macrolide resistance gene mreA of Streptococcus agalactiae encodes a flavokinase.

    PubMed

    Clarebout, G; Villers, C; Leclercq, R

    2001-08-01

    The mreA gene from Streptococcus agalactiae COH31 gamma/delta, resistant to macrolides and clindamycin by active efflux, has recently been cloned in Escherichia coli, where it was reported to confer macrolide resistance (J. Clancy, F. Dib-Hajj, J. W. Petitpas, and W. Yuan, Antimicrob. Agents Chemother. 41:2719--2723, 1997). Cumulative data suggested that the mreA gene was located on the chromosome of S. agalactiae COH31 gamma/delta. Analysis of the deduced amino acid sequence of mreA revealed significant homology with several bifunctional flavokinases/(flavin adenine dinucleotide (FAD) synthetases, which convert riboflavin to flavin mononucleotide (FMN) and FMN to FAD, respectively. High-performance liquid chromatography experiments showed that the mreA gene product had a monofunctional flavokinase activity, similar to that of RibR from Bacillus subtilis. Sequences identical to those of the mreA gene and of a 121-bp upstream region containing a putative promoter were detected in strains of S. agalactiae UCN4, UCN5, and UCN6 susceptible to macrolides. mreA and its allele from S. agalactiae UCN4 were cloned on the shuttle vector pAT28. Both constructs were introduced into E. coli, where they conferred a similar two- to fourfold increase in the MICs of erythromycin, spiramycin, and clindamycin. The MICs of a variety of other molecules, including crystal violet, acriflavin, sodium dodecyl sulfate, and antibiotics, such as certain cephalosporins, chloramphenicol, doxycycline, nalidixic acid, novobiocin, and rifampin, were also increased. In contrast, resistance to these compounds was not detected when the constructs were introduced into E. faecalis JH2-2. In conclusion, the mreA gene was probably resident in S. agalactiae and may encode a metabolic function. We could not provide any evidence that it was responsible for macrolide resistance in S. agalactiae COH31 gamma/delta; broad-spectrum resistance conferred by the gene in E. coli could involve multidrug efflux pumps

  6. Screening for cephalosporin-resistant Streptococcus pneumoniae with the Kirby-Bauer disk susceptibility test.

    PubMed

    Friedland, I R; Shelton, S; McCracken, G H

    1993-06-01

    Kirby-Bauer disk susceptibility tests with five standard cephalosporin disks were performed on 23 penicillin-resistant Streptococcus pneumoniae isolates for which ceftriaxone MICs were 0.125 to 4 micrograms/ml. Cefuroxime disk inhibition zone diameters distinguished clearly isolates for which ceftriaxone MICs were > or = 2 micrograms/ml from more susceptible strains, whereas cephalothin, ceftizoxime, cefotaxime, and ceftriaxone disks distinguished these isolates less clearly than the cefuroxime disk did.

  7. Cloning in Streptococcus lactis of plasmid-mediated UV resistance and effect on prophage stability

    SciTech Connect

    Chopin, M.C.; Chopin, A.; Rouault, A.; Simon, D.

    1986-02-01

    Plasmid pIL7 (33 kilobases) from Streptococcus lactis enhances UV resistance and prophage stability. A 5.4-kilobase pIL7 fragment carrying genes coding for both characters was cloned into S. lactis, using plasmid pHV1301 as the cloning vector. The recombinant plasmid was subsequently transferred to three other S. lactis strains by transformation or protoplast fusion. Cloned genes were expressed in all tested strains.

  8. Characterization of Tetracycline-Resistant Streptococcus thermophilus Isolates from Italian Soft Cheeses▿

    PubMed Central

    Rizzotti, Lucia; La Gioia, Federica; Dellaglio, Franco; Torriani, Sandra

    2009-01-01

    Tetracycline-resistant Streptococcus thermophilus isolates from soft cheeses harbored the genes tet(S), tet(M), and tet(L). Molecular analysis of these genes revealed their expression, localization on plasmids or Tn916-Tn1545 family transposons, and their similarity with published sequences. The study highlights the importance of an accurate safety assessment of using S. thermophilus as a starter culture. PMID:19395571

  9. Antibiotic Susceptibility and Mechanisms of Erythromycin Resistance in Clinical Isolates of Streptococcus agalactiae: French Multicenter Study

    PubMed Central

    De Mouy, Dany; Cavallo, Jean-Didier; Leclercq, Roland; Fabre, Roland

    2001-01-01

    Among 126 Streptococcus agalactiae isolates collected in 10 French laboratories in 1999, 27 (21.4%) had macrolide resistance related to the presence of erm(B) (11 strains), erm(A) subclass erm(TR) (10 strains), and mef(A) genes (2 strains) and the presence of combinations of erm(B) and erm(A) genes or mef(A) genes (3 strains). PMID:11451709

  10. Whole-Genome Sequence Analysis of Antimicrobial Resistance Genes in Streptococcus uberis and Streptococcus dysgalactiae Isolates from Canadian Dairy Herds.

    PubMed

    Vélez, Julián Reyes; Cameron, Marguerite; Rodríguez-Lecompte, Juan Carlos; Xia, Fangfang; Heider, Luke C; Saab, Matthew; McClure, J Trenton; Sánchez, Javier

    2017-01-01

    The objectives of this study are to determine the occurrence of antimicrobial resistance (AMR) genes using whole-genome sequence (WGS) of Streptococcus uberis (S. uberis) and Streptococcus dysgalactiae (S. dysgalactiae) isolates, recovered from dairy cows in the Canadian Maritime Provinces. A secondary objective included the exploration of the association between phenotypic AMR and the genomic characteristics (genome size, guanine-cytosine content, and occurrence of unique gene sequences). Initially, 91 isolates were sequenced, and of these isolates, 89 were assembled. Furthermore, 16 isolates were excluded due to larger than expected genomic sizes (>2.3 bp × 1,000 bp). In the final analysis, 73 were used with complete WGS and minimum inhibitory concentration records, which were part of the previous phenotypic AMR study, representing 18 dairy herds from the Maritime region of Canada (1). A total of 23 unique AMR gene sequences were found in the bacterial genomes, with a mean number of 8.1 (minimum: 5; maximum: 13) per genome. Overall, there were 10 AMR genes [ANT(6), TEM-127, TEM-163, TEM-89, TEM-95, Linb, Lnub, Ermb, Ermc, and TetS] present only in S. uberis genomes and 2 genes unique (EF-TU and TEM-71) to the S. dysgalactiae genomes; 11 AMR genes [APH(3'), TEM-1, TEM-136, TEM-157, TEM-47, TetM, bl2b, gyrA, parE, phoP, and rpoB] were found in both bacterial species. Two-way tabulations showed association between the phenotypic susceptibility to lincosamides and the presence of linB (P = 0.002) and lnuB (P < 0.001) genes and the between the presence of tetM (P = 0.015) and tetS (P = 0.064) genes and phenotypic resistance to tetracyclines only for the S. uberis isolates. The logistic model showed that the odds of resistance (to any of the phenotypically tested antimicrobials) was 4.35 times higher when there were >11 AMR genes present in the genome, compared with <7 AMR genes (P < 0.001). The odds of resistance was lower for S

  11. Whole-Genome Sequence Analysis of Antimicrobial Resistance Genes in Streptococcus uberis and Streptococcus dysgalactiae Isolates from Canadian Dairy Herds

    PubMed Central

    Vélez, Julián Reyes; Cameron, Marguerite; Rodríguez-Lecompte, Juan Carlos; Xia, Fangfang; Heider, Luke C.; Saab, Matthew; McClure, J. Trenton; Sánchez, Javier

    2017-01-01

    The objectives of this study are to determine the occurrence of antimicrobial resistance (AMR) genes using whole-genome sequence (WGS) of Streptococcus uberis (S. uberis) and Streptococcus dysgalactiae (S. dysgalactiae) isolates, recovered from dairy cows in the Canadian Maritime Provinces. A secondary objective included the exploration of the association between phenotypic AMR and the genomic characteristics (genome size, guanine–cytosine content, and occurrence of unique gene sequences). Initially, 91 isolates were sequenced, and of these isolates, 89 were assembled. Furthermore, 16 isolates were excluded due to larger than expected genomic sizes (>2.3 bp × 1,000 bp). In the final analysis, 73 were used with complete WGS and minimum inhibitory concentration records, which were part of the previous phenotypic AMR study, representing 18 dairy herds from the Maritime region of Canada (1). A total of 23 unique AMR gene sequences were found in the bacterial genomes, with a mean number of 8.1 (minimum: 5; maximum: 13) per genome. Overall, there were 10 AMR genes [ANT(6), TEM-127, TEM-163, TEM-89, TEM-95, Linb, Lnub, Ermb, Ermc, and TetS] present only in S. uberis genomes and 2 genes unique (EF-TU and TEM-71) to the S. dysgalactiae genomes; 11 AMR genes [APH(3′), TEM-1, TEM-136, TEM-157, TEM-47, TetM, bl2b, gyrA, parE, phoP, and rpoB] were found in both bacterial species. Two-way tabulations showed association between the phenotypic susceptibility to lincosamides and the presence of linB (P = 0.002) and lnuB (P < 0.001) genes and the between the presence of tetM (P = 0.015) and tetS (P = 0.064) genes and phenotypic resistance to tetracyclines only for the S. uberis isolates. The logistic model showed that the odds of resistance (to any of the phenotypically tested antimicrobials) was 4.35 times higher when there were >11 AMR genes present in the genome, compared with <7 AMR genes (P < 0.001). The odds of resistance was lower for S

  12. Fluoroquinolone-resistant Streptococcus agalactiae isolates from Argentina.

    PubMed

    Faccone, D; Guerriero, L; Méndez, E; Errecalde, L; Cano, H; Yoyas, N; Togneri, A; Romanowski, V; Galas, M; Whonet, Red; Corso, A

    2010-01-01

    Fluoroquinolone resistance is a growing problem that has only recently emerged in S. agalactiae. Between 2005-2007, WHONET--Argentina network evaluated levofloxacin susceptibility in 1128 clinical S. agalactiae isolates, 10 (0.9%) of which proved to be resistant. Nine of them had come from 5 hospitals (in Buenos Aires City and 4 Argentinean provinces) and recovered from urine (n=7) and vaginal screening cultures (n=2). Three strains were also resistant to macrolides, lincosamides and B streptogramins due to the ermA gene. All nine fluoroquinolone-resistant isolates bore the same two mutations, Ser79Phe in ParC and Ser81Leu in GyrA proteins. Genetic relationships were analyzed by Apal-PFGE and two clones were determined, A (n=6) and B (n=3). To our knowledge, these are the first fluoroquinolone-resistant S. agalactiae isolates detected in Latin America.

  13. Connection between trimethoprim-sulfamethoxazole use and resistance in Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

    PubMed

    Kärpänoja, Pauliina; Nyberg, Solja T; Bergman, Miika; Voipio, Tinna; Paakkari, Pirkko; Huovinen, Pentti; Sarkkinen, Hannu

    2008-07-01

    The association between trimethoprim-sulfamethoxazole use and resistance among the major respiratory tract pathogens was investigated by comparing regional consumption of the drug to regional resistance in the following year in 21 central hospital districts in Finland. A total of 23,530 Streptococcus pneumoniae isolates, 28,320 Haemophilus influenzae isolates, and 14,138 Moraxella catarrhalis isolates were tested for trimethoprim-sulfamethoxazole susceptibility during the study period (1998-2004). Among the S. pneumoniae isolates, a statistically significant connection was found between regional consumption and resistance. No statistically significant connection was found between regional trimethoprim-sulfamethoxazole use and resistance among H. influenzae and M. catarrhalis isolates. According to our results, it seems that only in pneumococci can the development of trimethoprim-sulfamethoxazole resistance be influenced by restricting its use. However, trimethoprim-sulfamethoxazole remains an important antimicrobial agent because of its reasonable price. Hence, resistance to trimethoprim-sulfamethoxazole among these pathogens needs continuous monitoring.

  14. Connection between Trimethoprim-Sulfamethoxazole Use and Resistance in Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis▿

    PubMed Central

    Kärpänoja, Pauliina; Nyberg, Solja T.; Bergman, Miika; Voipio, Tinna; Paakkari, Pirkko; Huovinen, Pentti; Sarkkinen, Hannu

    2008-01-01

    The association between trimethoprim-sulfamethoxazole use and resistance among the major respiratory tract pathogens was investigated by comparing regional consumption of the drug to regional resistance in the following year in 21 central hospital districts in Finland. A total of 23,530 Streptococcus pneumoniae isolates, 28,320 Haemophilus influenzae isolates, and 14,138 Moraxella catarrhalis isolates were tested for trimethoprim-sulfamethoxazole susceptibility during the study period (1998-2004). Among the S. pneumoniae isolates, a statistically significant connection was found between regional consumption and resistance. No statistically significant connection was found between regional trimethoprim-sulfamethoxazole use and resistance among H. influenzae and M. catarrhalis isolates. According to our results, it seems that only in pneumococci can the development of trimethoprim-sulfamethoxazole resistance be influenced by restricting its use. However, trimethoprim-sulfamethoxazole remains an important antimicrobial agent because of its reasonable price. Hence, resistance to trimethoprim-sulfamethoxazole among these pathogens needs continuous monitoring. PMID:18443116

  15. Novel Bacteriophage Lysin with Broad Lytic Activity Protects against Mixed Infection by Streptococcus pyogenes and Methicillin-Resistant Staphylococcus aureus

    PubMed Central

    Gilmer, Daniel B.; Schmitz, Jonathan E.; Euler, Chad W.

    2013-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pyogenes (group A streptococcus [GrAS]) cause serious and sometimes fatal human diseases. They are among the many Gram-positive pathogens for which resistance to leading antibiotics has emerged. As a result, alternative therapies need to be developed to combat these pathogens. We have identified a novel bacteriophage lysin (PlySs2), derived from a Streptococcus suis phage, with broad lytic activity against MRSA, vancomycin-intermediate S. aureus (VISA), Streptococcus suis, Listeria, Staphylococcus simulans, Staphylococcus epidermidis, Streptococcus equi, Streptococcus agalactiae (group B streptococcus [GBS]), S. pyogenes, Streptococcus sanguinis, group G streptococci (GGS), group E streptococci (GES), and Streptococcus pneumoniae. PlySs2 has an N-terminal cysteine-histidine aminopeptidase (CHAP) catalytic domain and a C-terminal SH3b binding domain. It is stable at 50°C for 30 min, 37°C for >24 h, 4°C for 15 days, and −80°C for >7 months; it maintained full activity after 10 freeze-thaw cycles. PlySs2 at 128 μg/ml in vitro reduced MRSA and S. pyogenes growth by 5 logs and 3 logs within 1 h, respectively, and exhibited a MIC of 16 μg/ml for MRSA. A single, 2-mg dose of PlySs2 protected 92% (22/24) of the mice in a bacteremia model of mixed MRSA and S. pyogenes infection. Serially increasing exposure of MRSA and S. pyogenes to PlySs2 or mupirocin resulted in no observed resistance to PlySs2 and resistance to mupirocin. To date, no other lysin has shown such notable broad lytic activity, stability, and efficacy against multiple, leading, human bacterial pathogens; as such, PlySs2 has all the characteristics to be an effective therapeutic. PMID:23571534

  16. Allelic Variation of the Capsule Promoter Diversifies Encapsulation and Virulence In Streptococcus pneumoniae

    PubMed Central

    Wen, Zhensong; Liu, Yanni; Qu, Fen; Zhang, Jing-Ren

    2016-01-01

    The polysaccharide capsule is the major virulence factor of Streptococcus pneumoniae (pneumococcus), a major human pathogen. The sequences in the promoter and coding regions of the capsule gene locus undergo extensive variations through the natural transformation-mediated horizontal gene transfer. The sequence variations in the coding region have led to at least 97 capsular serotypes. However, it remains unclear whether the sequence polymorphisms in the promoter region have any biological significance. In this study, we determined the sequences of the cps promoter region from 225 invasive pneumococcal isolates, and identified modular composition and remarkable inter-strain sequence variations in this region. The strain-to strain variations in the cps promoter are characterized by diversity in sequence and size, mosaic combinations of nucleotide polymorphisms and sequence modules, selective preservation of the sequence combinations, and promiscuous assortments of the sequences between the promoter and coding regions. Isogenic pneumococci carrying allelic variants of the cps promoter displayed significant differences in the transcription of the capsule genes, capsule production, adhesion to host epithelial cells, anti-phagocytosis and virulence in mouse bacteremia model. This study has thus indicated that the sequence polymorphisms in the cps promoter represent a novel mechanism for fine-tuning the level of encapsulation and virulence among S. pneumoniae strains. PMID:27465908

  17. Comparative Genomic Analysis of the Streptococcus dysgalactiae Species Group: Gene Content, Molecular Adaptation, and Promoter Evolution

    PubMed Central

    Suzuki, Haruo; Lefébure, Tristan; Hubisz, Melissa Jane; Pavinski Bitar, Paulina; Lang, Ping; Siepel, Adam; Stanhope, Michael J.

    2011-01-01

    Comparative genomics of closely related bacterial species with different pathogenesis and host preference can provide a means of identifying the specifics of adaptive differences. Streptococcus dysgalactiae (SD) is comprised of two subspecies: S. dysgalactiae subsp. equisimilis is both a human commensal organism and a human pathogen, and S. dysgalactiae subsp. dysgalactiae is strictly an animal pathogen. Here, we present complete genome sequences for both taxa, with analyses involving other species of Streptococcus but focusing on adaptation in the SD species group. We found little evidence for enrichment in biochemical categories of genes carried by each SD strain, however, differences in the virulence gene repertoire were apparent. Some of the differences could be ascribed to prophage and integrative conjugative elements. We identified approximately 9% of the nonrecombinant core genome to be under positive selection, some of which involved known virulence factors in other bacteria. Analyses of proteomes by pooling data across genes, by biochemical category, clade, or branch, provided evidence for increased rates of evolution in several gene categories, as well as external branches of the tree. Promoters were primarily evolving under purifying selection but with certain categories of genes evolving faster. Many of these fast-evolving categories were the same as those associated with rapid evolution in proteins. Overall, these results suggest that adaptation to changing environments and new hosts in the SD species group has involved the acquisition of key virulence genes along with selection of orthologous protein-coding loci and operon promoters. PMID:21282711

  18. A novel gene amplification causes upregulation of the PatAB ABC transporter and fluoroquinolone resistance in Streptococcus pneumoniae.

    PubMed

    Baylay, Alison J; Ivens, Alasdair; Piddock, Laura J V

    2015-01-01

    Overexpression of the ABC transporter genes patA and patB confers efflux-mediated fluoroquinolone resistance in Streptococcus pneumoniae and is also linked to pneumococcal stress responses. Although upregulation of patAB has been observed in many laboratory mutants and clinical isolates, the regulatory mechanisms controlling expression of these genes are unknown. In this study, we aimed to identify the cause of high-level constitutive overexpression of patAB in M184, a multidrug-resistant mutant of S. pneumoniae R6. Using a whole-genome transformation and sequencing approach, we identified a novel duplication of a 9.2-kb region of the M184 genome which included the patAB genes. This duplication did not affect growth and was semistable with a low segregation rate. The expression levels of patAB in M184 were much higher than those that could be fully explained by doubling of the gene dosage alone, and inactivation of the first copy of patA had no effect on multidrug resistance. Using a green fluorescent protein reporter system, increased patAB expression was ascribed to transcriptional read-through from a tRNA gene upstream of the second copy of patAB. This is the first report of a large genomic duplication causing antibiotic resistance in S. pneumoniae and also of a genomic duplication causing antibiotic resistance by a promoter switching mechanism.

  19. Consumption Patterns and In Vitro Resistance of Streptococcus pneumoniae to Fluoroquinolones▿

    PubMed Central

    Simoens, Steven; Verhaegen, Jan; van Bleyenbergh, Pascal; Peetermans, Willy E.; Decramer, Marc

    2011-01-01

    This article analyzes patterns of consumption of fluoroquinolones and documents the in vitro resistances of Streptococcus pneumoniae isolates to fluoroquinolones in the ambulatory care setting in Belgium over time. The volume of fluoroquinolone consumption has fallen consistently since 2003. Fluoroquinolones were used primarily for their registered indications (i.e., urinary tract infections and lower respiratory tract infections). The MIC distributions of moxifloxacin and levofloxacin in S. pneumoniae isolates remained stable during 2004 to 2009, and the level of resistance to moxifloxacin and levofloxacin was low (≤1%). PMID:21464243

  20. Consumption patterns and in vitro resistance of Streptococcus pneumoniae to fluoroquinolones.

    PubMed

    Simoens, Steven; Verhaegen, Jan; van Bleyenbergh, Pascal; Peetermans, Willy E; Decramer, Marc

    2011-06-01

    This article analyzes patterns of consumption of fluoroquinolones and documents the in vitro resistances of Streptococcus pneumoniae isolates to fluoroquinolones in the ambulatory care setting in Belgium over time. The volume of fluoroquinolone consumption has fallen consistently since 2003. Fluoroquinolones were used primarily for their registered indications (i.e., urinary tract infections and lower respiratory tract infections). The MIC distributions of moxifloxacin and levofloxacin in S. pneumoniae isolates remained stable during 2004 to 2009, and the level of resistance to moxifloxacin and levofloxacin was low (≤1%).

  1. Apparent involvement of a multidrug transporter in the fluoroquinolone resistance of Streptococcus pneumoniae.

    PubMed Central

    Baranova, N N; Neyfakh, A A

    1997-01-01

    A Streptococcus pneumoniae strain selected for resistance to ethidium bromide demonstrated enhanced energy-dependent efflux of this toxic dye. Both the ethidium resistance and the ethidium efflux could be inhibited by the plant alkaloid reserpine. The ethidium-selected cells demonstrated cross-resistance to the fluoroquinolones norfloxacin and ciprofloxacin; this resistance could also be completely reversed by reserpine. Furthermore, reserpine potentiated the susceptibility of wild-type S. pneumoniae to fluoroquinolones and ethidium. The most plausible explanation for these results is that S. pneumoniae, like some other gram-positive bacteria, expresses a reserpine-sensitive multidrug transporter, which may play an important role in both intrinsic and acquired resistances of this pathogen to fluoroquinolone therapy. PMID:9174208

  2. Promoter Identification and Transcription Analysis of Penicillin-Binding Protein Genes in Streptococcus pneumoniae R6

    PubMed Central

    Peters, Katharina; Pipo, Julia; Schweizer, Inga; Hakenbeck, Regine

    2016-01-01

    Penicillin-binding proteins (PBPs) are membrane-associated enzymes, which are involved in the last two steps of peptidoglycan biosynthesis, and some of them are key players in cell division. Furthermore, they are targets of β-lactams, the most widely used antibiotics. Nevertheless, very little is known about the expression and regulation of PBP genes. Using transcriptional mapping, we now determined the promoter regions of PBP genes from the laboratory strain Streptococcus pneumoniae R6 and examined the expression profile of these six promoters. The extended −10 region is highly conserved and complies with a σA-type promoter consensus sequence. In contrast, the −35 region is poorly conserved, indicating the possibility for differential PBP regulation. All PBP promoters were constitutively expressed and highly active during the exponential and early stationary growth phase. However, the individual expression of PBP promoters varied approximately fourfold, with pbp1a being the highest and pbp3 the lowest. Furthermore, the deletion of one nucleotide in the spacer region of the PBP3 promoter reduced pbp3 expression ∼10-fold. The addition of cefotaxime above the minimal inhibitory concentration (MIC) did not affect PBP expression in the penicillin-sensitive R6 strain. No evidence for regulation of S. pneumoniae PBP genes was obtained. PMID:27409661

  3. Promoter Identification and Transcription Analysis of Penicillin-Binding Protein Genes in Streptococcus pneumoniae R6.

    PubMed

    Peters, Katharina; Pipo, Julia; Schweizer, Inga; Hakenbeck, Regine; Denapaite, Dalia

    2016-09-01

    Penicillin-binding proteins (PBPs) are membrane-associated enzymes, which are involved in the last two steps of peptidoglycan biosynthesis, and some of them are key players in cell division. Furthermore, they are targets of β-lactams, the most widely used antibiotics. Nevertheless, very little is known about the expression and regulation of PBP genes. Using transcriptional mapping, we now determined the promoter regions of PBP genes from the laboratory strain Streptococcus pneumoniae R6 and examined the expression profile of these six promoters. The extended -10 region is highly conserved and complies with a σ(A)-type promoter consensus sequence. In contrast, the -35 region is poorly conserved, indicating the possibility for differential PBP regulation. All PBP promoters were constitutively expressed and highly active during the exponential and early stationary growth phase. However, the individual expression of PBP promoters varied approximately fourfold, with pbp1a being the highest and pbp3 the lowest. Furthermore, the deletion of one nucleotide in the spacer region of the PBP3 promoter reduced pbp3 expression ∼10-fold. The addition of cefotaxime above the minimal inhibitory concentration (MIC) did not affect PBP expression in the penicillin-sensitive R6 strain. No evidence for regulation of S. pneumoniae PBP genes was obtained.

  4. Intravitreal Ampicillin Sodium for Antibiotic-Resistant Endophthalmitis: Streptococcus uberis First Human Intraocular Infection Report

    PubMed Central

    Velez-Montoya, Raul; Rascón-Vargas, Dulce; Mieler, William F.; Fromow-Guerra, Jans; Morales-Cantón, Virgilio

    2010-01-01

    Purpose. To describe the clinical characteristics, diagnosis, and treatment with intravitreal ampicillin sodium of a postoperative endophthalmitis case due to Streptococcus uberis; an environmental pathogen commonly seen in mastitis cases of lactating cows. Methods. Case Report. A 52-year-old, Hispanic diabetic patient who suddenly developed severe pain and severe loss of vision, following vitrectomy. Results. The patient was diagnosed with postoperative endophthalmitis secondary to a highly resistant strain of Streptococcus uberis that did not respond to intravitreal antibiotics. He was treated with an air-fluid interchange, anterior chamber washout, intravitreal ampicillin sodium (5 mg/0.1 mL), and silicon oil tamponade (5000 ck). The eye was anatomically stabilized, though there was no functional recovery. Conclusion. Streptococcus uberis is an uncommon pathogen to the human eye, which has unique features that help the strain in developing resistance to antibiotics. While treatment with intravitreal ampicillin is feasible, there are still concerns about its possible toxicity. PMID:20706679

  5. [Resistance phenotypes and genotypes of Streptococcus pyogenes clinical isolates in Chile over a 10-year period].

    PubMed

    Rodríguez, Carlos; Rojas, Pablo; Wozniak, Aniela; Kalergis, Alexis M; Cerón, Inés; Riedel, Ingrid; Román, Juan C; Villarroel, Luis A; Berríos, Ximena; Bavestrello, Luis; García, Patricia

    2011-09-01

    Macrolide and lincosamide resistance in Streptococcus pyogenes is due to the acquisition of mef, ermB and ermA genes, which confer different resistance phenotypes, namely M, MLSBconstitutive and MLSBinducible respectively. The last report of resistance in Chile was done in the period 1990-1998, in which resistance to macrolides was 5.4%, with M phenotype as the predominant one. To characterize the evolution of erythromycin and clindamycin resistance and their associated genes in S. pyogenes strains isolated from patients with invasive and non-invasive infections in the period 1996 to 2005. Resistance to erythromycin and clindamycin was determined in 1,282 clinical isolates using the disk diffusion test. Resistant isolates were analyzed by polymerase chain reaction (PCR) for the presence of the above mentioned resistance genes. Global resistance to erythromycin and clindamycin was 3.5 and 0.7% respectively. Eighty percent of the resistant strains possessed the M. phenotype. Resistance levels of S. pyogenes have decreased in Chile in the last years. Most resistant strains have M phenotype in contrast to many countries in which the MLSB constitutive phenotype is the predominant one.

  6. Streptococcus agalactiae from pregnant women: antibiotic and heavy-metal resistance mechanisms and molecular typing.

    PubMed

    Rojo-Bezares, B; Azcona-Gutiérrez, J M; Martin, C; Jareño, M S; Torres, C; Sáenz, Y

    2016-11-01

    We investigated the antibiotic and heavy-metal resistance mechanisms, virulence genes and clonal relationships of macrolide- and/or lincosamide-resistant (M+/-LR) Streptococcus agalactiae (group B Streptococcus, GBS) isolates from pregnant women in La Rioja in Northern Spain, a region with a significant immigrant population. In total 375 GBS isolates were recovered during 2011. About three-quarters of isolates were from European nationals and the remainder distributed among 23 other nationalities. Seventy-five (20%) were classified as M+/-LR strains and 28 (37%) of these were resistant to ⩾3 classes of antibiotics. Capsular serotypes III (29·3%), V (21·3%) and II (12%) were the most frequent. A wide variety of antibiotic resistance genes were detected in M+/-LR strains; notably, 5·3% harboured the lsa(C) gene associated with cross-resistance, and tet(W) was identified in a single strain. We report, for the first time, the detection of cadmium and copper resistance encoded by tcrB + cadA + cadC genes in 20 M+/-LR strains, which raises the possibility of co-selection of antibiotic and heavy-metal resistance disseminated through mobile genetic elements. The M+/-LR strains were highly diverse by DNA macrorestriction profiles (65 patterns) and 16 multilocus sequence types (STs) distributed among six clonal complexes; the most frequent were ST1, ST19, and ST12, and two strains were novel (ST586 and ST601). In conclusion, a wide diversity of genetic lineages of macrolide, lincosamide and heavy-metal- resistant GBS strains was observed in an ethnically diverse maternal population.

  7. Asymptomatic throat carriage rate and antimicrobial resistance pattern of Streptococcus pyogenes in Nepalese school children.

    PubMed

    Dumre, S P; Sapkota, K; Adhikari, N; Acharya, D; Karki, M; Bista, S; Basanyat, S R; Joshi, S K

    2009-01-01

    Streptococcus pyogenes or Group A streptococcus (GAS) causes several suppurative and non suppurative infections. In addition to pharyngitis and skin infections, GAS are also the causative agent of post-streptococcal infection syndromes such as acute rheumatic fever (ARF) and post-streptococcal glumerulonephritis (PSG). GAS frequently colonises in the throat of an asymptomatic person. Pharyngeal carriage rates of GAS among healthy school children vary with geographical location and seasons. We carried out this preliminary study to determine the throat carriage rate and antimicrobial resistance trend of Streptococcus pyogenes or Group A streptococcus (GAS) among the Nepalese school children. Four schools situated at different locations of Kathmandu valley were included in the study. Throat swabs from 350 students of age group 5-15 years were collected, immediately transported to the laboratory and were processed for S. pyogenes following standard microbiological procedures. Antimicrobial susceptibility testing of the isolates was performed by Kirby Bauer disc diffusion method following CLSI guidelines. S. pyogenes was isolated from 10.9% (38/350) of the screened children. The GAS colonisation rate was statistically insignificant (P>0.05) with sex and age sub-groups, although the rate was slightly higher among girls and age sub-group 9-12 years. No significant difference in carrier rate was observed among different schools (P>0.05). All isolates were susceptible to azithromycin. No resistance was detected for penicillin and its derivative antibiotic ampicillin. Highest resistance rate was observed for cotrimoxazole (71.0%) followed by chloramphenicol (7.8%), ciprofloxacin (5.2%) and erythromycin (5.2%). Antibiotic resistant GAS isolated from asymptomatic Nepalese school children is a public health concern. When screened and appropriately treated with antibiotics, carriers can be prevented from spreading of streptococcal infections in the school environment and the

  8. Resistance to multiple fluoroquinolones in a clinical isolate of Streptococcus pyogenes: identification of gyrA and parC and specification of point mutations associated with resistance.

    PubMed

    Yan, S S; Fox, M L; Holland, S M; Stock, F; Gill, V J; Fedorko, D P

    2000-11-01

    A strain of Streptococcus pyogenes resistant to multiple fluoroquinolones was isolated from the blood of an immunocompromised patient. Resistance to fluoroquinolones in S. pyogenes has not been previously studied. Compared to 10 sensitive strains of S. pyogenes, the fluoroquinolone-resistant clinical isolate of S. pyogenes presented point mutations in gyrA, predicting that serine-81 was changed to phenylalanine and that methionine-99 was changed to leucine, and in parC, predicting that serine-79 was changed to tyrosine. The mechanism of fluoroquinolone resistance in this isolate of S. pyogenes appears to be analogous to previously reported mechanisms for Streptococcus pneumoniae.

  9. Resistance to Multiple Fluoroquinolones in a Clinical Isolate of Streptococcus pyogenes: Identification of gyrA and parC and Specification of Point Mutations Associated with Resistance

    PubMed Central

    Yan, S. Steve; Fox, Melissa L.; Holland, Steven M.; Stock, Frida; Gill, Vee J.; Fedorko, Daniel P.

    2000-01-01

    A strain of Streptococcus pyogenes resistant to multiple fluoroquinolones was isolated from the blood of an immunocompromised patient. Resistance to fluoroquinolones in S. pyogenes has not been previously studied. Compared to 10 sensitive strains of S. pyogenes, the fluoroquinolone-resistant clinical isolate of S. pyogenes presented point mutations in gyrA, predicting that serine-81 was changed to phenylalanine and that methionine-99 was changed to leucine, and in parC, predicting that serine-79 was changed to tyrosine. The mechanism of fluoroquinolone resistance in this isolate of S. pyogenes appears to be analogous to previously reported mechanisms for Streptococcus pneumoniae. PMID:11036052

  10. The association between antibiotic use in the community and nasopharyngeal carriage of antibiotic-resistant Streptococcus pneumoniae in Bedouin children.

    PubMed

    Greenberg, David; Givon-Lavi, Noga; Sharf, Amir Z; Vardy, Daniel; Dagan, Ron

    2008-09-01

    The objective of the study was to evaluate whether the increase in antibiotic-resistant Streptococcus pneumoniae carriage was associated with antibiotic use in the community in children in Southern Israel. All the prescriptions given to Bedouin children <5 years old enlisted in 2 sentinel primary pediatric clinics treating approximately 20% of the Bedouin pediatric population of this age range were recorded, from 1998 to 2005. Nasopharyngeal pneumococcal isolates obtained during the same period from healthy children <5 years old were collected and antibiotic susceptibility was determined. A total of 1488 of 1927 (77.7%) cultures were positive for S. pneumoniae. The proportion of S. pneumoniae with penicillin minimal inhibitory concentration > or = 1.0 microg/mL increased from 8% to 21% (P < 0.01); resistance to clindamycin from 9% to 22%; resistance to erythromycin from 13% to 30%; resistance to tetracycline from 13% to 31%; and multidrug resistance from 16% to 30%. The total annual antibiotic prescription rates decreased by 19%, from 3867 to 3191 prescriptions per 1000 children (P < 0.001). This was mainly the result of a reduction in amoxicillin +/- clavulanate prescriptions (from 3046 to 2582; P < 0.001). Oral cephalosporin, erythromycin and penicillin prescription rates decreased significantly as well (P < 0.001) whereas azithromycin prescription rates increased significantly (P < 0.001). We suggest that the increased carriage of S. pneumoniae resistant to multiple antibiotics is possibly associated to the increased azithromycin consumption. Reduction of total antibiotic use may not be sufficient as long as antibiotics with high potential to promote multidrug resistance, given their pharmacokinetics and pharmacodynamics characteristics, are widely used.

  11. Antibodies against a Surface Protein of Streptococcus pyogenes Promote a Pathological Inflammatory Response

    PubMed Central

    Kahn, Fredrik; Mörgelin, Matthias; Shannon, Oonagh; Norrby-Teglund, Anna; Herwald, Heiko; Olin, Anders I.; Björck, Lars

    2008-01-01

    Streptococcal toxic shock syndrome (STSS) caused by Streptococcus pyogenes is a clinical condition with a high mortality rate despite modern intensive care. A key feature of STSS is excessive plasma leakage leading to hypovolemic hypotension, disturbed microcirculation and multiorgan failure. Previous work has identified a virulence mechanism in STSS where M1 protein of S. pyogenes forms complexes with fibrinogen that activate neutrophils to release heparin-binding protein (HBP), an inducer of vascular leakage. Here, we report a marked inter-individual difference in the response to M1 protein–induced HBP release, a difference found to be related to IgG antibodies directed against the central region of the M1 protein. To elicit massive HBP release, such antibodies need to be part of the M1 protein–fibrinogen complexes. The data add a novel aspect to bacterial pathogenesis where antibodies contribute to the severity of disease by promoting a pathologic inflammatory response. PMID:18787689

  12. Genomic analyses of DNA transformation and penicillin resistance in Streptococcus pneumoniae clinical isolates.

    PubMed

    Fani, Fereshteh; Leprohon, Philippe; Zhanel, George G; Bergeron, Michel G; Ouellette, Marc

    2014-01-01

    Alterations in penicillin-binding proteins, the target enzymes for β-lactam antibiotics, are recognized as primary penicillin resistance mechanisms in Streptococcus pneumoniae. Few studies have analyzed penicillin resistance at the genome scale, however, and we report the sequencing of S. pneumoniae R6 transformants generated while reconstructing the penicillin resistance phenotypes from three penicillin-resistant clinical isolates by serial genome transformation. The genome sequences of the three last-level transformants T2-18209, T5-1983, and T3-55938 revealed that 16.2 kb, 82.7 kb, and 137.2 kb of their genomes had been replaced with 5, 20, and 37 recombinant sequence segments derived from their respective parental clinical isolates, documenting the extent of DNA transformation between strains. A role in penicillin resistance was confirmed for some of the mutations identified in the transformants. Several multiple recombination events were also found to have happened at single loci coding for penicillin-binding proteins (PBPs) that increase resistance. Sequencing of the transformants with MICs for penicillin similar to those of the parent clinical strains confirmed the importance of mosaic PBP2x, -2b, and -1a as a driving force in penicillin resistance. A role in resistance for mosaic PBP2a was also observed for two of the resistant clinical isolates.

  13. Two-Year Surveillance of Antibiotic Resistance in Streptococcus pneumoniae in Four African Cities

    PubMed Central

    Benbachir, Mohamed; Benredjeb, Saida; Boye, Cheick Saadbouh; Dosso, Mireille; Belabbes, Houria; Kamoun, Aouatef; Kaire, Omar; Elmdaghri, Naima

    2001-01-01

    Worldwide spread of antibiotic resistance in Streptococcus pneumoniae is a major problem. However, data from West and North African countries are scarce. To study the level of resistance and compare the situations in different cities, a prospective study was conducted in Abidjan (Ivory Coast), Casablanca (Morocco), Dakar (Senegal), and Tunis (Tunisia), from 1996 to 1997. The resistances to eight antibiotics of 375 isolates were studied by E test, and the results were interpreted using the breakpoints recommended by the National Committee for Clinical Laboratory Standards. Overall, 30.4% of the isolates were nonsusceptible to penicillin G (25.6% were intermediate and 4.8% were resistant). Amoxicillin (96.3% were susceptible) and parenteral third-generation cephalosporins (92.7%) were highly active. Resistance to chloramphenicol was detected in 8.6% of the isolates. High levels of resistance were noted for erythromycin (28%), tetracycline (38.3%), and cotrimoxazole (36.4%). Resistance to rifampin was rare (2.1%). There were significant differences in resistance rates between individual countries. Multiple resistance was more frequent in penicillin-nonsusceptible isolates than in penicillin-susceptible isolates. Recommendations for treatment could be generated from these results in each participating country. PMID:11158769

  14. Predominant role of msr(D) over mef(A) in macrolide resistance in Streptococcus pyogenes.

    PubMed

    Zhang, Yan; Tatsuno, Ichiro; Okada, Ryo; Hata, Nanako; Matsumoto, Masakado; Isaka, Masanori; Isobe, Ken-ichi; Hasegawa, Tadao

    2016-01-01

    In Japan, the number of patients with streptococcal toxic shock syndrome is reported to be increasing. mef(A) gene-positive macrolide-resistant emm1 strains are thought to possibly contribute to the rise in the frequency of STSS. Although analyses of macrolide-resistant mechanisms, including mef(A) resistance, have been performed mainly in Streptococcus pneumoniae, the role of this gene in Streptococcus pyogenes has not been completely investigated. Therefore, to the best of our knowledge, we established the first mef(A)-knockout strain using an emm1-type S. pyogenes strain, and tested its susceptibility to erythromycin, clarithromycin and azithromycin. We found that the antimicrobial susceptibilities were almost identical to those of the parental strain. Hence, we established a knockout strain for another gene, msr(D), that is located immediately downstream of mef(A). The macrolide resistances of the resulting strain significantly decreased, and were further altered when both mef(A) and msr(D) were knocked out. The introduction of the msr(D) gene into a macrolide-sensitive strain conferred more resistance than the introduction of the mef(A) gene. The erythromycin susceptibilities of knockout strains were further dissected using two additional emm4- and emm75-type S. pyogenes strains. We found almost identical results for both strains except for the mef(A) knockout emm4 type, whose susceptibility was altered, although the change was less than that for the msr(D) knockout. These results suggest that both mef(A) and msr(D) are involved in macrolide resistance in S. pyogenes, and that the msr(D) gene plays a more predominant role in macrolide resistance than mef(A).

  15. Molecular Basis of Resistance to Selected Antimicrobial Agents in the Emerging Zoonotic Pathogen Streptococcus suis

    PubMed Central

    Gurung, Mamata; Tamang, Migma Dorji; Moon, Dong Chan; Kim, Su-Ran; Jeong, Jin-Ha; Jang, Geum-Chan; Jung, Suk-Chan; Park, Yong-Ho

    2015-01-01

    Characterization of 227 Streptococcus suis strains isolated from pigs during 2010 to 2013 showed high levels of resistance to clindamycin (95.6%), tilmicosin (94.7%), tylosin (93.8%), oxytetracycline (89.4%), chlortetracycline (86.8%), tiamulin (72.7%), neomycin (70.0%), enrofloxacin (56.4%), penicillin (56.4%), ceftiofur (55.9%), and gentamicin (55.1%). Resistance to tetracyclines, macrolides, aminoglycosides, and fluoroquinolone was attributed to the tet gene, erm(B), erm(C), mph(C), and mef(A) and/or mef(E) genes, aph(3′)-IIIa and aac(6′)-Ie-aph(2″)-Ia genes, and single point mutations in the quinolone resistance-determining region of ParC and GyrA, respectively. PMID:25903569

  16. Molecular Basis of Resistance to Selected Antimicrobial Agents in the Emerging Zoonotic Pathogen Streptococcus suis.

    PubMed

    Gurung, Mamata; Tamang, Migma Dorji; Moon, Dong Chan; Kim, Su-Ran; Jeong, Jin-Ha; Jang, Geum-Chan; Jung, Suk-Chan; Park, Yong-Ho; Lim, Suk-Kyung

    2015-07-01

    Characterization of 227 Streptococcus suis strains isolated from pigs during 2010 to 2013 showed high levels of resistance to clindamycin (95.6%), tilmicosin (94.7%), tylosin (93.8%), oxytetracycline (89.4%), chlortetracycline (86.8%), tiamulin (72.7%), neomycin (70.0%), enrofloxacin (56.4%), penicillin (56.4%), ceftiofur (55.9%), and gentamicin (55.1%). Resistance to tetracyclines, macrolides, aminoglycosides, and fluoroquinolone was attributed to the tet gene, erm(B), erm(C), mph(C), and mef(A) and/or mef(E) genes, aph(3')-IIIa and aac(6')-Ie-aph(2″)-Ia genes, and single point mutations in the quinolone resistance-determining region of ParC and GyrA, respectively.

  17. Evolving trends in Streptococcus pneumoniae resistance: implications for therapy of community-acquired bacterial pneumonia.

    PubMed

    Jones, Ronald N; Jacobs, Michael R; Sader, Helio S

    2010-09-01

    Pneumonia is a major infectious disease associated with significant morbidity, mortality and utilisation of healthcare resources. Streptococcus pneumoniae is the predominant pathogen in community-acquired pneumonia (CAP), accounting for 20-60% of bacterial cases. Emergence of multidrug-resistant S. pneumoniae has become a significant problem in the management of CAP. Although pneumococcal conjugate vaccine usage in children has led to significant decreases in morbidity and mortality due to S. pneumoniae in all age groups, disease management has been further complicated by the unexpected increase in resistant serotypes, such as 19A, in some regions. Until rapid and accurate diagnostic tests become available, initial treatment of CAP will remain empirical. Thus, selection of appropriate antimicrobial therapy for CAP must be based on prediction of the most likely pathogens and their local antimicrobial susceptibility patterns. This article reviews information on antimicrobial resistance patterns amongst S. pneumoniae and implications for managing CAP.

  18. NSR from Streptococcus agalactiae confers resistance against nisin and is encoded by a conserved nsr operon.

    PubMed

    Khosa, Sakshi; AlKhatib, Zainab; Smits, Sander H J

    2013-11-01

    Nisin is a lantibiotic produced by Lactococcus lactis (L. lactis), which is active against many Gram-positive bacteria. However, in various pathogenic and nonpathogenic bacteria, the presence of a nisin resistance protein (NSR) confers resistance against nisin. Here, we show that NSR from Streptococcus agalactiae (SaNSR) confers 20-fold resistance when expressed in L. lactis. We also show that SaNSR is encoded by an operon structure comprising of a lipoprotein and an ATP-binding cassette transporter as well as a two-component system that is putatively involved in expression and regulation. This organization of the operon is conserved in several (non)pathogenic strains that do not produce nisin themselves.

  19. Multiple changes of penicillin-binding proteins in penicillin-resistant clinical isolates of Streptococcus pneumoniae.

    PubMed Central

    Hakenbeck, R; Tarpay, M; Tomasz, A

    1980-01-01

    Penicillin-binding properties and characteristics of penicillin-binding proteins (PBPs) were investigated in several clinical isolates of Streptococcus pneumoniae differing in their susceptibilities to penicillin (minimal inhibitory concentration [MIC], 0.03 to 0.5 microgram/ml) and compared with the penicillin-susceptible strain R36A (MIC, 0.07 microgram/ml). Several changes accompanied the development of resistance: the relative affinity to penicillin of whole cells, isolated membranes, and two major PBPs after in vivo or in vitro labeling decreased (with increasing resistance). Furthermore, one additional PBP (2') appeared in four of five relatively resistant strains with an MIC of 0.25 microgram/ml and higher. PBP 3 maintained the same high affinity toward penicillin in all strains under all labeling conditions. Images PMID:7425601

  20. [Antibiotic therapy for community acquired Streptococcus pneumoniae pneumonia: clinical relevance of antibiotic resistance].

    PubMed

    Bédos, J-P; Bruneel, F

    2006-01-01

    The emergence of Streptococcus pneumoniae strains with reduced susceptibility to beta-lactams and with multiple drug resistance has not led to major changes in recommendations for antibiotic therapy in patients with acute community-acquired pneumococcal pneumonia. Numerous factors explain the limited clinical impact of this major microbiological change. The frequency of intermediate strains is high but the frequency of resistant strains to beta-lactams is very low. There is a complex relation between the acquisition of resistance to beta-lactams and the decreased virulence of S. pneumoniae strains. The only finding in studies of humanized experimental animal models of lethal bacteremic pneumonia caused by resistance and tolerant strains was a slowing in the kinetics of beta-lactams bactericidal activity, especially for amoxicillin. Taken together, this preclinical data shows that microbiological resistance of pneumococci to beta-lactams has very little influence on a possible failure of recommanded treatment regimens for pneumococcal pneumonia. The high rate of multiple drug resistance, particularly among beta-lactam resistant strains, rules out the probabilistic use of macrolides. Conversely, fluoroquinolone (FQ) resistance remains low, inferior to 3%, and the same is true for ketolides (<1%). Only a global strategy of patient management in the use of these new drugs could ensure their long-term activity. The high mortality rate of hospitalized S. pneumoniae pneumonia will only be improved with a better understanding of the complex host-bacteria interactions.

  1. Conjugative transfer of resistance determinants among human and bovine Streptococcus agalactiae

    PubMed Central

    Pinto, Tatiana Castro Abreu; Costa, Natália Silva; Corrêa, Ana Beatriz de Almeida; de Oliveira, Ivi Cristina Menezes; de Mattos, Marcos Correa; Rosado, Alexandre Soares; Benchetrit, Leslie Claude

    2014-01-01

    Streptococcus agalactiae (GBS) is a major source of human perinatal diseases and bovine mastitis. Erythromycin (Ery) and tetracycline (Tet) are usually employed for preventing human and bovine infections although resistance to such agents has become common among GBS strains. Ery and Tet resistance genes are usually carried by conjugative transposons (CTns) belonging to the Tn916 family, but their presence and transferability among GBS strains have not been totally explored. Here we evaluated the presence of Tet resistance genes (tetM and tetO) and CTns among Ery-resistant (Ery-R) and Ery-susceptible (Ery-S) GBS strains isolated from human and bovine sources; and analyzed the ability for transferring resistance determinants between strains from both origins. Tet resistance and int-Tn genes were more common among Ery-R when compared to Ery-S isolates. Conjugative transfer of all resistance genes detected among the GBS strains included in this study (ermA, ermB, mef, tetM and tetO), in frequencies between 1.10−7 and 9.10−7, was possible from bovine donor strains to human recipient strain, but not the other way around. This is, to our knowledge, the first report of in vitro conjugation of Ery and Tet resistance genes among GBS strains recovered from different hosts. PMID:25477908

  2. emm Gene distribution among erythromycin-resistant and -susceptible Italian isolates of Streptococcus pyogenes.

    PubMed

    Zampaloni, Claudia; Cappelletti, Paola; Prenna, Manuela; Vitali, Luca Agostino; Ripa, Sandro

    2003-03-01

    The phenotypes and genetic determinants for macrolide resistance were determined for 167 erythromycin-resistant Streptococcus pyogenes strains. A cMLS phenotype was shown in 18% of the erythromycin-resistant strains, while inducible resistance was apparent in 31% and the M phenotype was apparent in 50%. The emm gene type of this set of resistant isolates and that of 48 erythromycin-sensitive isolates were determined. emm2 and emm48 were recorded only in the resistant strains of the M phenotype, while approximately all of the strains harboring the emm22 gene had the cMLS phenotype. More than 80% of the emm89-positive strains had the iMLS phenotype, and the same portion of emm4 strains presented the M phenotype. emm3 is recorded only among sensitive strains. The distribution of frequencies of the genetic determinant for the virulence factor M protein was significantly different both among organisms of different types of resistance and between resistant and sensitive populations of S. pyogenes under study.

  3. emm Gene Distribution among Erythromycin-Resistant and -Susceptible Italian Isolates of Streptococcus pyogenes

    PubMed Central

    Zampaloni, Claudia; Cappelletti, Paola; Prenna, Manuela; Vitali, Luca Agostino; Ripa, Sandro

    2003-01-01

    The phenotypes and genetic determinants for macrolide resistance were determined for 167 erythromycin-resistant Streptococcus pyogenes strains. A cMLS phenotype was shown in 18% of the erythromycin-resistant strains, while inducible resistance was apparent in 31% and the M phenotype was apparent in 50%. The emm gene type of this set of resistant isolates and that of 48 erythromycin-sensitive isolates were determined. emm2 and emm48 were recorded only in the resistant strains of the M phenotype, while approximately all of the strains harboring the emm22 gene had the cMLS phenotype. More than 80% of the emm89-positive strains had the iMLS phenotype, and the same portion of emm4 strains presented the M phenotype. emm3 is recorded only among sensitive strains. The distribution of frequencies of the genetic determinant for the virulence factor M protein was significantly different both among organisms of different types of resistance and between resistant and sensitive populations of S. pyogenes under study. PMID:12624074

  4. Macrolide and Tetracycline Resistance and emm Type Distribution of Streptococcus pyogenes Isolates Recovered from Turkish Patients

    PubMed Central

    Sayan, Murat; Tamer, Gulden Sonmez

    2010-01-01

    The aims of this study were to determine the susceptibilities to macrolide and tetracycline antibiotics and emm type distribution of Streptococcus pyogenes strains isolated in the Kocaeli University Hospital, Turkey. A total of 127 S. pyogenes clinical isolates were tested. Eleven (9%) isolates were resistant to erythromycin, and 23 (18%) isolates were resistant to tetracycline. Ten of the erythromycin-resistant isolates were also resistant to tetracycline. By the triple-disk test, all erythromycin-resistant isolates showed the inducible macrolide-lincosamide-streptogramin-C phenotype and harbored erm(TR) gene. tet(O) was the most common tetracycline resistance gene. Among erythromycin-tetracycline coresistant isolates, seven harbored the tet(O) gene. emm 4, emm 1, emm 2,114, and emm 89 were the most common emm types. These isolates were more susceptible to erythromycin. There was considerable emm type heterogeneity in macrolide or tetracycline resistant isolates. According to our knowledge, this is the first study in which emm type distribution is investigated in Turkey. More comprehensive studies are needed to obtain true information about the epidemiology of macrolide and tetracycline resistance and emm type distribution in Turkey. PMID:20624096

  5. [Antibiotic resistance in Streptococcus pneumoniae strains isolated from sterile body sites].

    PubMed

    Oznur, A K; Ozer, Serdar; Benzonana, Nur A

    2006-07-01

    Antibiotic resistance in Streptococcus pneumoniae has become an important issue in the last years. Penicillin resistance rates vary among countries and among different regions in countries. It is important to know penicillin resistance rates among isolates, in planning empirical antimicrobial therapy in pneumococcal infections. In this study, the antibiotic resistance rates of S. pneumoniae strains isolated from sterile body sites were investigated with both E-test and disc diffusion methods for penicillin, erythromycin, levofloxacin, and with only disc diffusion method for chloramphenicol, ceftriaxone, vancomycin, rifampin, trimethoprim-sulfamethoxazole (TMP-SMX), clindamycin, and tetracycline. A total of 165 strains were included into the study of which 52 were isolated from blood, 46 from cerebrospinal fluids, 25 from pleural fluids, 24 from dacryocystitis materials, 13 from tympanocentesis materials, 3 from joint fluids and 2 from wound specimens. Intermediate resistance to penicilin was 18.8%, while the resistance rates to TMP-SMX, tetracycline, chloramphenicol, erythromycin and levofloxacin were detected as 21.2%, 10.9%, 9.7%, 5.4% and 0.6%, respectively. None of the isolates were highly resistant to penicillin, nor resistant to vancomycin, ceftriaxone and rifampin. In conclusion, penicillin is still the first line therapeutic agent for pneumococcal infections except for severe infections such as meningitis, in our region.

  6. Brain orexin promotes obesity resistance

    PubMed Central

    Kotz, Catherine; Nixon, Joshua; Butterick, Tammy; Perez-Leighton, Claudio; Teske, Jennifer; Billington, Charles

    2012-01-01

    Resistance to obesity is becoming an exception rather than the norm, and understanding mechanisms that lead some to remain lean in spite of an obesigenic environment is critical if we are to find new ways to reverse this trend. Levels of energy intake and physical activity both contribute to body weight management, but it is challenging for most to adopt major long-term changes in either factor. Physical activity outside of formal exercise, also referred to as activity of daily living, and in stricter form, spontaneous physical activity (SPA), may be an attractive modifiable variable for obesity prevention. In this review, we discuss individual variability in SPA and NEAT (nonexercise thermogenesis, or the energy expended by SPA) and its relationship to obesity resistance. The hypothalamic neuropeptide orexin (hypocretin) may play a key role in regulating SPA and NEAT. We discuss how elevated orexin signaling capacity, in the context of a brain network modulating SPA, may play a major role in defining individual variability in SPA and NEAT. Greater activation of this SPA network leads to a lower propensity for fat mass gain and therefore may be an attractive target for obesity prevention and therapy. PMID:22803681

  7. Genotyping and serotyping of macrolide and multidrug resistant Streptococcus pneumoniae isolated from carrier children.

    PubMed

    Swedan, S F; Hayajneh, W A; Bshara, G N

    2016-01-01

    Streptococcus pneumoniae, an opportunistic pathogen commonly carried asymptomatically in the nasopharynx of children, is associated with increasing rates of treatment failures due to a worldwide increase in drug resistance. We investigated the carriage of S. pneumoniae in children 5 years or younger, the identity of prevalent serotypes, the rates of resistance to macrolides and other antimicrobial agents and the genotypes responsible for macrolide resistance. Nasopharyngeal swabs were collected from 157 children under 5 years for cultural isolation of S. pneumoniae. Antibiogram of isolates  was determined using the disk diffusion test, and the minimal inhibitory concentration to macrolides was determined using the E-test. Isolate serotypes and macrolide resistance genes, erm(B) and mef(E), were identified using multiplex polymerase chain reactions. S. pneumoniae was recovered from 33.8% of children; 41.9% among males and 21.9% among females (P = 0.009). The highest carriage rate occurred among age groups 7-12 months and 49-60 months. Most frequent serotypes were 19F, 6A/B, 11A, 19A, 14 and 15B/C.  Resistance to macrolides was 60.4%. Resistance to oxacillin, trimethoprim/sulfamethoxazole and clindamycin was present among 90.6%, 54.7% and 32.1% of isolates, respectively. All isolates were susceptible to chloramphenicol, levofloxacin and vancomycin. Isolates resistant to one or more macrolide drugs were more likely to be multidrug resistant. Resistance to clindamycin or oxacillin coexisted with macrolide resistance. Among the erythromycin-resistant isolates, erm(B), mef(E) and erm(B) and mef(E) genes were present at rates of 43.8%, 37.5% and 6.3%, respectively. Erm(B) and mef(E) were associated with very high level and moderate-to-high level resistance to macrolides, respectively. A significant proportion of children harboured macrolide and multidrug-resistant S. pneumoniae.

  8. Saliva-promoted adhesion of Streptococcus mutans MT8148 associates with dental plaque and caries experience.

    PubMed

    Shimotoyodome, A; Kobayashi, H; Tokimitsu, I; Hase, T; Inoue, T; Matsukubo, T; Takaesu, Y

    2007-01-01

    Colonization of enamel surfaces by Streptococcus mutans is thought to be initiated by the attachment of bacteria to a saliva-derived conditioning film (acquired pellicle). However, the clinical relevance of the contribution of saliva-promoted S. mutans adhesion in biofilm formation has not yet been fully elucidated. The aim of this study was to correlate saliva-promoted S. mutans adhesion with biofilm formation in humans. We correlated all measurements of salivary factors and dental plaque formation in 70 healthy subjects. Dental plaque development after thorough professional teeth cleaning correlated positively with S. mutans adhesion onto saliva-coated hydroxyapatite pellets and the glycoprotein content of either parotid or whole saliva. Saliva-promoted S. mutans adhesion and glycoprotein content were also positively correlated with each other in parotid and whole saliva. By contrast, neither salivary mutans streptococci, Lactobacillus nor Candida correlated with biofilm formation. Parotid saliva-mediated S. mutans adhesion was significantly higher in 12 caries-experienced (CE) subjects than in 9 caries-inexperienced (CI) subjects. Salivary S. mutans adhesion was significantly less (p < 0.01) in the CI group than in the CE group. In conclusion, the present findings suggest the initial S. mutans adhesion, modulated by salivary protein adsorption onto the enamel surface, as a possible correlate of susceptibility to dental plaque and caries. Copyright 2007 S. Karger AG, Basel.

  9. Comparative Genomics Study of Multi-Drug-Resistance Mechanisms in the Antibiotic-Resistant Streptococcus suis R61 Strain

    PubMed Central

    Zhang, Anding; Wu, Jiayan; Chen, Bo; Hua, Yafeng; Yu, Jun; Chen, Huanchun; Xiao, Jingfa; Jin, Meilin

    2011-01-01

    Background Streptococcus suis infections are a serious problem for both humans and pigs worldwide. The emergence and increasing prevalence of antibiotic-resistant S. suis strains pose significant clinical and societal challenges. Results In our study, we sequenced one multi-drug-resistant S. suis strain, R61, and one S. suis strain, A7, which is fully sensitive to all tested antibiotics. Comparative genomic analysis revealed that the R61 strain is phylogenetically distinct from other S. suis strains, and the genome of R61 exhibits extreme levels of evolutionary plasticity with high levels of gene gain and loss. Our results indicate that the multi-drug-resistant strain R61 has evolved three main categories of resistance. Conclusions Comparative genomic analysis of S. suis strains with diverse drug-resistant phenotypes provided evidence that horizontal gene transfer is an important evolutionary force in shaping the genome of multi-drug-resistant strain R61. In this study, we discovered novel and previously unexamined mutations that are strong candidates for conferring drug resistance. We believe that these mutations will provide crucial clues for designing new drugs against this pathogen. In addition, our work provides a clear demonstration that the use of drugs has driven the emergence of the multi-drug-resistant strain R61. PMID:21966396

  10. Molecular characterization of a novel mosaic tet(S/M) gene encoding tetracycline resistance in foodborne strains of Streptococcus bovis.

    PubMed

    Barile, Simona; Devirgiliis, Chiara; Perozzi, Giuditta

    2012-09-01

    The presence of antibiotic-resistance (AR) genes in foodborne bacteria of enteric origin represents a relevant threat to human health in the case of opportunistic pathogens, which can reach the human gut through the food chain. Streptococcus bovis is a human opportunistic pathogen often associated with infections in immune-compromised or cancer patients, and it can also be detected in the environment, including fermented foods. We have focused on the molecular characterization of a tetracycline (Tet)-resistance gene present in 39 foodborne isolates of S. bovis phenotypically resistant to this drug. The gene was identified as a novel tet(S/M) fusion, encoding a mosaic protein composed of the N-terminal 33 amino acids of Tet(S), in-frame with the Tet(M) coding sequence. Heterologous expression of the mosaic gene was found to confer Tet resistance upon Escherichia coli recipients. Moreover, the tet(S/M) gene was found to be transcriptionally inducible by Tet under the endogenous tet(S) promoter in both S. bovis and E. coli. Nucleotide sequencing of the surrounding genomic region of 16.2 kb revealed large blocks of homology with the genomes of Streptococcus infantarius and Lactococcus lactis. A subregion of about 4 kb containing mosaic tet(S/M) was flanked by two copies of the IS1216 mobile element. PCR amplification with primers directed outwards from the tet(S/M) gene identified the presence of a 4.3 kb circular form corresponding to the intervening chromosomal region between the two IS1216 elements, but lacking a replication origin. The circular element shared extensive overall homology with a region of the multidrug-resistance plasmid pK214 from Lc. lactis, containing tet(S), as well as the IS1216 transposase-containing element and intervening non-coding sequences. Linear reconstruction of the insertion events likely to have occurred within this genomic region, inferred from sequence homology, provides further evidence of the chromosomal rearrangements that drive

  11. High Prevalence of Inducible Erythromycin Resistance among Streptococcus bovis Isolates in Taiwan

    PubMed Central

    Teng, Lee-Jene; Hsueh, Po-Ren; Ho, Shen-Wu; Luh, Kwen-Tay

    2001-01-01

    Susceptibilities to 13 antimicrobial agents were determined by measurement of MICs for 60 isolates of Streptococcus bovis from blood cultures. Thirty-eight isolates (63.3%) had high-level resistance to erythromycin (MICs, ≥128 μg/ml). Among the 38 erythromycin-resistant strains, 21 isolates (55%) had inducible resistance to macrolides-lincosamides-streptogramin B (iMLS isolates) and 17 (45%) had constitutive resistance to macrolides-lincosamides-streptogramin B (cMLS isolates). Tetracycline resistance was also found among all of the erythromycin-resistant strains. None of the strains displayed resistance to penicillin, chloramphenicol, or vancomycin. Detection of erythromycin resistance genes by PCR and sequencing indicated that all 17 cMLS isolates were positive for the ermB gene and that 7 of 21 iMLS isolates carried the ermB gene and the remaining 14 iMLS isolates carried the ermT gene. Sequence analysis of amplified partial ermB fragments (594 bp) from S. bovis isolates revealed a 99.8% nucleotide identity and a 100% amino acid homology compared with the sequences from gene banks. The sequences of amplified fragments with primers targeted for ermC were shown to be very similar to that of ermGT (ermT) from Lactobacillus reuteri (98.5% nucleotide identity). This is the first report to describe the detection of the ermT class of erythromycin resistance determinants in S. bovis. The high rate of inducible erythromycin resistance among S. bovis isolates in Taiwan was not reported before. The iMLS S. bovis isolates were shown to be heterogeneous by randomly amplified polymorphic DNA analysis. These results indicate that the prevalence of inducible erythromycin resistance in S. bovis in Taiwan is very high and that most of the resistant strains carry the ermT or the ermB gene. PMID:11709309

  12. Change in antibiotic resistance of group B streptococcus: impact on intrapartum management.

    PubMed

    Morales, W J; Dickey, S S; Bornick, P; Lim, D V

    1999-08-01

    Intrapartum chemoprophylaxis has resulted in a significant reduction of group B Streptococcus neonatal infection. For penicillin-allergic patients, clindamycin or erythromycin is the recommended antibiotic. The purpose of this study was to establish any pattern of antibiotic resistance of group B streptococcal clinical isolates over the past 15 years. Group B streptococcal isolates obtained from the lower genital tract were tested for sensitivity to ampicillin, penicillin, clindamycin, and erythromycin. The sensitivity of 100 group B streptococcal isolates retrieved in the period 1997-1998 was compared with that of 85 group B streptococcal isolates from 1980-1993. From 1980-1993 group B streptococcal isolates were available for testing for antibiotic resistance along with 100 isolates from a second study period 1997-1998. Of the 100 group B streptococcal isolates from 1997-1998, 18 were resistant to erythromycin, of which 5 were also resistant to clindamycin, as compared with 1 of the 85 isolates from 1980-1993 that was resistant to erythromycin (P <.001). All the isolates were sensitive to ampicillin and penicillin. All 18 resistant strains from 1997-1998 were found to be sensitive to cephalothin. Over the past 18 years there has been increased in vitro resistance of group B streptococci to both clindamycin and erythromycin. If other studies confirm these findings, modifications to the current Centers for Disease Control and Prevention recommendations may be necessary.

  13. Macrolide resistance in group A beta haemolytic Streptococcus isolated from outpatient children in Latvia.

    PubMed

    Zavadska, Dace; Bērziņa, Dace; Drukaļska, Līga; Pugacova, Nina; Miklasevics, Edvīns; Gardovska, Dace

    2010-05-01

    Group A streptococci (GAS) are responsible for up to 30% of cases of pharyngitis in children, and such children do not benefit from treatment with antibiotics. During the last decade, increased resistance to macrolides has emerged as a critical issue in the treatment of GAS pharyngitis. The objective of this study was to determine the antimicrobial resistance of group A beta haemolytic Streptococcus isolated from outpatient children. From 2002 to 2006, 96 GAS strains were obtained from the pharynx of outpatients having symptoms of acute pharyngitis. Antibiotic resistance was determined by disc susceptibility tests according to CLSI standards. The presence of ermA, ermB and mefA was established by the amplification of streptococcal DNA with specific primers. Antimicrobial susceptibility tests revealed that all the strains tested were sensitive to vancomycin, linezolid, penicillin and ceftriaxone. Simultaneously, high levels of resistance to macrolides were evident; 78% of the isolates were resistant to clindamycin and erythromycin. No significant change in the yearly or seasonal incidence of resistance was observed. We describe high antimicrobial resistance of GAS to macrolides in outpatient children (78%), which can be explained by the frequent use of macrolides in the treatment of such individuals. Therefore, macrolides should not be the first drug of choice.

  14. Antimicrobial resistance and virulence-related genes of Streptococcus obtained from dairy cows with mastitis in Inner Mongolia, China.

    PubMed

    Ding, Yuexia; Zhao, Junli; He, Xiuling; Li, Man; Guan, Hong; Zhang, Ziying; Li, Peifeng

    2016-01-01

    Mastitis is the most expensive disease in the dairy cattle industry and results in decreased reproductive performance. Streptococcus, especially Streptococcus agalactiae, possesses a variety of virulence factors that contribute to pathogenicity. Streptococcus isolated from mastitis was tested to assess the prevalence of antimicrobial resistance and distribution of antibiotic resistance- and virulence-related genes. Eighty-one Streptococcus isolates were phenotypically characterized for antimicrobial resistance against 15 antibiotics by determining minimum inhibitory concentrations (MIC) using a micro-dilution method. Resistance- and virulence-related genes were detected by PCR. High percentage of resistance to β-lactams, along with tetracycline and erythromycin, was found. Resistance to three or more of seven antimicrobial agents was observed at 88.9%, with penicillin-tetracycline-erythromycin-clindamycin as the major profile in Streptococcus isolates. Resistant genes were detected by PCR, the result showed that 86.4, 86.4, 81.5, and 38.3% of isolates were mainly carrying the pbp2b, tetL, tetM, and ermB genes, respectively. Nine virulence genes were investigated. Genes cyl, glnA, cfb, hylB, and scaA were found to be in 50% of isolates, while 3.7, 21, and 4.9% of isolates were positive for bca, lmb, and scpB, genes, respectively. None of the isolates carried the bac gene. This study suggests the need for prudent use of antimicrobial agents in veterinary clinical medicine to avoid the increase and dissemination of antimicrobial resistance arising from the use of antimicrobial drugs in animals.

  15. Multicenter Study of the Mechanisms of Resistance and Clonal Relationships of Streptococcus agalactiae Isolates Resistant to Macrolides, Lincosamides, and Ketolides in Spain

    PubMed Central

    Gonzalez, J. J.; Andreu, A.

    2005-01-01

    Macrolide, lincosamide, and ketolide mechanisms of resistance and clonal relationships were characterized in a collection of 79 resistant group B streptococcus isolates obtained from neonates or pregnant women. The erm(B), erm(TR), and mef(A) genes were present in 62%, 30.4%, and 3.8% of the isolates, respectively. There was considerable clonal diversity among them. PMID:15917563

  16. Genotypic and phenotypic detection of macrolide and lincosamide resistance in Streptococcus uberis.

    PubMed

    Schmitt-Van de Leemput, E; Zadoks, R N

    2007-11-01

    Streptococcus uberis isolates (n = 55) were obtained from milk samples of cases of mild clinical mastitis in 55 dairy cows from 35 herds serviced by one veterinary practice in Mayenne, France. Isolates were tested for macrolide and lincosamide resistance by using phenotypic and genotypic methods. Erythromycin resistance was detected in 12 of the 55 (22%) isolates based on agar disc diffusion testing and MIC measurements, and was encoded by ermB. This gene also conferred phenotypic resistance to pirlimycin based on MIC measurements, but the D-test was needed for detection of the resistance phenotype in the agar disc diffusion test. Isolates with ermB were also highly resistant to the macrolide antibiotic spiramycin. Seventeen of the 55 isolates (31%) were classified as resistant to spiramcyin only and as having intermediate susceptibility to spiramycin based on agar disc diffusion testing and MIC measurements, respectively. The genetic mechanism behind this phenotype and its clinical relevance are unknown. The efflux pump gene mefA was not detected in any of the 55 isolates in this study. Pirlimycin resistance without macrolide resistance was encoded by the lincosamide resistance gene linB in 4 isolates. Based on current guidelines, some linB-positive isolates would be classified as susceptible by using phenotypic tests, and alternative values for the interpretation of the agar disc diffusion test are suggested. We conclude that the agar disc diffusion test is a useful indicator for macrolide and lincosamide resistance of Strep. uberis in veterinary practice, provided that the D-test is used for detection of pirlimycin resistance.

  17. Subinhibitory concentrations of triclosan promote Streptococcus mutans biofilm formation and adherence to oral epithelial cells.

    PubMed

    Bedran, Telma Blanca Lombardo; Grignon, Louis; Spolidorio, Denise Palomari; Grenier, Daniel

    2014-01-01

    Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs) of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.

  18. Subinhibitory Concentrations of Triclosan Promote Streptococcus mutans Biofilm Formation and Adherence to Oral Epithelial Cells

    PubMed Central

    Bedran, Telma Blanca Lombardo; Grignon, Louis; Spolidorio, Denise Palomari; Grenier, Daniel

    2014-01-01

    Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs) of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans. PMID:24551218

  19. A commensal streptococcus hijacks a Pseudomonas aeruginosa exopolysaccharide to promote biofilm formation.

    PubMed

    Scoffield, Jessica A; Duan, Dingyu; Zhu, Fan; Wu, Hui

    2017-04-01

    Pseudomonas aeruginosa causes devastating chronic pulmonary infections in cystic fibrosis (CF) patients. Although the CF airway is inhabited by diverse species of microorganisms interlaced within a biofilm, many studies focus on the sole contribution of P. aeruginosa pathogenesis in CF morbidity. More recently, oral commensal streptococci have been identified as cohabitants of the CF lung, but few studies have explored the role these bacteria play within the CF biofilm. We examined the interaction between P. aeruginosa and oral commensal streptococci within a dual species biofilm. Here we report that the CF P. aeruginosa isolate, FRD1, enhances biofilm formation and colonization of Drosophila melanogaster by the oral commensal Streptococcus parasanguinis. Moreover, production of the P. aeruginosa exopolysaccharide, alginate, is required for the promotion of S. parasanguinis biofilm formation and colonization. However, P. aeruginosa is not promoted in the dual species biofilm. Furthermore, we show that the streptococcal adhesin, BapA1, mediates alginate-dependent enhancement of the S. parasanguinis biofilm in vitro, and BapA1 along with another adhesin, Fap1, are required for the in vivo colonization of S. parasanguinis in the presence of FRD1. Taken together, our study highlights a new association between streptococcal adhesins and P. aeruginosa alginate, and reveals a mechanism by which S. parasanguinis potentially colonizes the CF lung and interferes with the pathogenesis of P. aeruginosa.

  20. [Problems with identification of beta-hemolytic streptococcus resistant to bacitracin isolated from patients with pharyngitis].

    PubMed

    Olender, Alina; Łetowska, Iwona; Karyński, Michał; Kiernicka-Ciekot, Katarzyna; Pels, Katarzyna

    2012-01-01

    The genus Streptococcus comprises a number of species characterized by a differential pathogenic potential. These bacteria can be considered as members of microbial physiological flora but they can also cause mild infections or severe, life threatening conditions. The majority of infections of streptococcal etiology are caused by beta-hemolysing species. The predominant causative agent of bacterial pharyngitis is Streptococcus pyogenes. This species usually doesn't give rise to any identification difficulties due to the introduction the well determined diagnostic schemes. Problems concerning laboratory identification can be, however, associated with other species of beta-hemolysing streptococci isolated from patients with pharyngitis. These streptococci can demonstrate features similar to those of S. pyogenes and share the group antygen A, such as some strains of Streptococcus anginosus and Streptococcus dysgalactiae subsp. equisimilis. The determination of sensitivity to bacitracin, which is a feature typical of S. pyogenes, is the basic test useful for its preliminary identification. Nevertheless, the identification of some strains by this test can give rise to incompatibility. The aim of the study was characterisation of beta-hemolysing streptococci resistant to bacitracin isolated from patients with pharyngitis. The examined bacterial strains caused identification problems by the use of routine diagnostic methods. The material included 14 streptococcal strains resistant to bacitracin which were isolated from adult patients suffering from pharyngitis. The bacteria were cultured on media dedicated for the species. The following routine diagnostic tests were used for the bacterial identification: sensitivity to bacitracin (0.04 U/disc), CAMP test, determination of the group antigens A, B, C, D, F and G (Slidex Strepto-Kit), and determination of biochemical features by the API 20 STREP test (bioMèrieux). The sensitivity of streptococcal isolates to antibiotics

  1. Identification, antimicrobial resistance and molecular characterization of the human emerging pathogen Streptococcus gallolyticus subsp. pasteurianus.

    PubMed

    Gherardi, Giovanni; Palmieri, Claudio; Marini, Emanuela; Pompilio, Arianna; Crocetta, Valentina; Di Bonaventura, Giovanni; Creti, Roberta; Facinelli, Bruna

    2016-12-01

    This study aimed to retrospectively identify 22Streptococcus bovis clinical strains based on the new taxonomy, as well as to investigate their antibiotic-resistance and clonality. Strains were identified by Phoenix100 system, 16S rRNA sequencing, and two MALDI-TOF MS platforms (Bruker Biotyper, Vitek MS). Antibiotic resistance was determined both phenotypically and genotypically, and clonality was assessed by PFGE. Most of strains (63.6%) were isolated from urine, and diabetes was the most common underlying disease (31.8%). Phoenix100 system revealed all strains belonged to biotype II, and 16S rRNA sequencing identified all strains as S. gallolyticus subsp pasteurianus (SGSP). Although both MALDI-TOF MS systems correctly identified isolates to the species level, only Bruker Biotyper accurately identified to the subspecies level. Erythromycin-resistant strains (31.8%) were also clindamycin-resistant and positive for erm(B). Strains resistant to tetracycline (68.2%) were also resistant to erythromycin. PFGE showed high genetic variability identifying 17 different pulsotypes, most of which single.

  2. Emergence and spread of Streptococcus pneumoniae with erm(B) and mef(A) resistance.

    PubMed

    Farrell, David J; Jenkins, Stephen G; Brown, Steven D; Patel, Manish; Lavin, Bruce S; Klugman, Keith P

    2005-06-01

    Streptococcus pneumoniae isolates (N = 31,001) were collected from patients with community-acquired respiratory tract infections during the PROTEKT US surveillance study (2000-2003). While the macrolide (erythromycin) resistance rate remained stable at approximately 29%, the prevalence of resistant isolates containing both erm(B) and mef(A) increased from 9.7% in year 1 to 16.4% in year 3, with substantial regional variability. Almost all (99.2%) dual erm(B) + mef(A) macrolide-resistant isolates exhibited multidrug resistance, whereas 98.6% and 99.0% were levofloxacin- and telithromycin-susceptible, respectively. These strains were most commonly isolated from the ear or middle-ear fluid of children. Of 152 representative erm(B)+mef(A) isolates, >90% were clonally related to the multidrug-resistant international Taiwan19F-14 clonal complex 271 (CC271). Of 366 erm(B)+mef(A) isolates from the PROTEKT global study (1999-2003), 83.3% were CC271, with the highest prevalence seen in South Africa, South Korea, and the United States. This study confirms the increasing global emergence and rapidly increasing US prevalence of this multidrug-resistant pneumococcal clone.

  3. [Antibiotic resistance of streptococcus pneumoniae among healthy nasopharyngeal carriers in seven regions of Peru].

    PubMed

    Torres, Nancy; Velásquez, Ricardo; Mercado, Erik H; Egoavil, Martha; Horna, Gertrudis; Mejía, Lida; Castillo, María E; Chaparro, Eduardo; Hernández, Roger; Silva, Wilda; Campos, Francisco E; Sáenz, Andrés; Hidalgo, Félix; Letona, Carolina; Valencia, Angel G; Cerpa, Rosario; López-de-Romaña, Bernardo; Torres, Berenice; Castillo, Fiorella; Calle, Andrea; Rabanal, Synthia; Pando, Jackeline; Lacroix, Elizabeth; Reyes, Isabel; Guerra, Humberto; Ochoa, Theresa J

    2013-01-01

    To determine the pattern of antibiotic susceptibility of isolated Streptococcus pneumoniae strains of healthy nasopharyngeal carriers younger than 2 years in seven regions of Peru. Between 2007 and 2009, nasopharyngeal swab samples were collected among 2123 healthy children aged 2-24 months in growth and development medical practices (CRED) and vaccination offices of hospitals and health centers in Lima, Piura, Cusco, Abancay, Arequipa, Huancayo, and Iquitos. The resistance to ten antibiotics through disk diffusion sensitivity testing of isolated pneumococcus strains was determined. 572 strains were isolated. High rates of resistance to co-trimoxazole (58%), penicillin (52.2% non-sensitive); tetracycline (29,1%); azithromycin (28,9%), and erythromycin (26,3%). Resistance to chloramphenicol was low (8.8%). Multiresistance was found at 29.5%. Resistance to azithromycin and penicillin was different in all seven regions (p<0,05), the highest percentage of non-sensitive strains being found in Arequipa (63,6%), whereas the lowest percentage was found in Cusco (23.4%). High levels of resistance found to penicillin, co-trimoxasole and macrolides in isolated pneumococcus strains of healthy carriers in all studied regions, and their association to a previous use of antibiotics, represent a significant public health problem in our country. This emphasizes the need to implement nationwide strategies to reduce the irrational use of antibiotics, especially among children. It is necessary to complement data of resistance to penicillin with the determination of minimal inhibitory concentration to make proper therapeutic recommendations.

  4. Changes in fluoroquinolone-resistant Streptococcus pneumoniae after 7-valent conjugate vaccination, Spain.

    PubMed

    de la Campa, Adela G; Ardanuy, Carmen; Balsalobre, Luz; Pérez-Trallero, Emilio; Marimón, Jose M; Fenoll, Asunción; Liñares, Josefina

    2009-06-01

    Among 4,215 Streptococcus pneumoniae isolates obtained in Spain during 2006, 98 (2.3%) were ciprofloxacin resistant (3.6% from adults and 0.14% from children). In comparison with findings from a 2002 study, global resistance remained stable. Low-level resistance (30 isolates with MIC 4-8 microg/mL) was caused by a reserpine-sensitive efflux phenotype (n = 4) or single topoisomerase IV (parC [n = 24] or parE [n = 1]) changes. One isolate did not show reserpine-sensitive efflux or mutations. High-level resistance (68 isolates with MIC >or=16 microg/mL) was caused by changes in gyrase (gyrA) and parC or parE. New changes in parC (S80P) and gyrA (S81V, E85G) were shown to be involved in resistance by genetic transformation. Although 49 genotypes were observed, clones Spain9V-ST156 and Sweden15A-ST63 accounted for 34.7% of drug-resistant isolates. In comparison with findings from the 2002 study, clones Spain14-ST17, Spain23F-ST81, and ST8819F decreased and 4 new genotypes (ST9710A, ST57016, ST43322, and ST71733) appeared in 2006.

  5. Dihydrofolate Reductase Activity in Strains of Streptococcus faecium var. durans Resistant to Methasquin and Amethopterin1

    PubMed Central

    Rader, Jeanne I.; Hutchison, Dorris J.

    1972-01-01

    Resistance to the antifolates methasquin and amethopterin has been studied in new strains of Streptococcus faecium var. durans. Two methasquin-resistant strains (SF/MQ, SF/MQT) and an amethopterin-resistant strain (SF/AM) were selected independently from the wild-type S. faecium var. durans (SF/O). SF/MQT is a thymine auxotroph. Total dihydrofolate reductase activity was elevated in each of the resistant strains. The greatest increase (36-fold) was observed in extracts of SF/AM. The methasquin-resistant strains, SF/MQ and SF/MQT, had 29-fold and 8-fold, respectively, more dihydrofolate reductase activity than the parental strain. Total dihydrofolate reductase activity of SF/O was separable by gel filtration into two components: a folate reductase (11%) and a specific dihydrofolate reductase (89%). Folate reductase activity was associated with 88% of the total dihydrofolate reductase activity of SF/MQT, with specific dihydrofolate reductase activity accounting for the remaining 12%. In SF/MQ and SF/AM, folate reductase activity was associated with 97% of the total dihydrofolate reductase activity. Studies of the inhibition by methasquin and amethopterin of partially purified folate reductase and specific dihydrofolate reductase of the mutant strains suggested that resistance was not accompanied by changes in the affinities of these enzymes for either antifolate. PMID:4401600

  6. Changes in Fluoroquinolone-Resistant Streptococcus pneumonia after 7-Valent Conjugate Vaccination, Spain

    PubMed Central

    Ardanuy, Carmen; Balsalobre, Luz; Pérez-Trallero, Emilio; Marimón, Jose M.; Fenoll, Asunción; Liñares, Josefina

    2009-01-01

    Among 4,215 Streptococcus pneumoniae isolates obtained in Spain during 2006, 98 (2.3%) were ciprofloxacin resistant (3.6% from adults and 0.14% from children). In comparison with findings from a 2002 study, global resistance remained stable. Low-level resistance (30 isolates with MIC 4–8 μg/mL) was caused by a reserpine-sensitive efflux phenotype (n = 4) or single topoisomerase IV (parC [n = 24] or parE [n = 1]) changes. One isolate did not show reserpine-sensitive efflux or mutations. High-level resistance (68 isolates with MIC ≥16 μg/mL) was caused by changes in gyrase (gyrA) and parC or parE. New changes in parC (S80P) and gyrA (S81V, E85G) were shown to be involved in resistance by genetic transformation. Although 49 genotypes were observed, clones Spain9V-ST156 and Sweden15A-ST63 accounted for 34.7% of drug-resistant isolates. In comparison with findings from the 2002 study, clones Spain14-ST17, Spain23F-ST81, and ST8819F decreased and 4 new genotypes (ST9710A, ST57016, ST43322, and ST71733) appeared in 2006. PMID:19523289

  7. High macrolide resistance in Streptococcus pyogenes strains isolated from children with pharyngitis in China.

    PubMed

    Liu, Xiaorong; Shen, Xuzhuang; Chang, Hesheng; Huang, Guoying; Fu, Zhou; Zheng, Yuejie; Wang, Libo; Li, Chengrong; Liu, Lan; Shen, Ying; Yang, Yonghong

    2009-05-01

    To assess the macrolide resistance, phenotype, and genotypic characterization of Streptococcus pyogenes isolated from Chinese children with pharyngitis. Minimal inhibitory concentration (MIC) with nine antibiotics was determined on 188 isolates of S. pyogenes collected from outpatients with pharyngitis in four children's hospitals in different regions of China in 2007. MICs of penicillin, chloramphenicol, cefradine, levofloxacin, macrolide (erythromycin, clarithromycin, azithromycin,), clindamycin, and tetracycline were determined by the microdilution method. The macrolide resistant phenotypes of isolates were determined through a double-disk. The macrolide-resistant genes (mefA, ermB, and ermA) were amplified by polymerase chain reaction (PCR). Over 95% were resistant to macrolides, while 92.0% were resistant to tetracycline. We also found that all isolates were sensitive to penicillin, chloramphenicol, cefradine, and levofloxacin. Among the 173 erythromycin resistant strains, 171 (98.8%) were assigned to the cMLS phenotype, while the remaining 2 (1.2%) were assigned to the iMLS phenotype. Among the 171 cMLS isolates, 168 isolates (98.2%) had the ermB gene accounting for 98.2%. Meanwhile, 2 iMLS isolates had the ermA gene. Macrolides were highly resistant to ermB positive strains (MIC(90) > 256 microg/ml). Neither the M-phenotype nor the mefA gene was detected. Meanwhile, our studies of multiple centers showed that consumption of macrolides from 2000 to 2006 was very high. The main phenotype is cMLS, and the ermB gene code is the main resistance mechanism against macrolides in S. pyogenes. The high rate of macrolide resistance to S. pyogenes was observed, which may be correlated with the overuse of these antibiotics in China. (c) 2009 Wiley-Liss, Inc.

  8. Active efflux as a mechanism of resistance to ciprofloxacin in Streptococcus pneumoniae.

    PubMed Central

    Zeller, V; Janoir, C; Kitzis, M D; Gutmann, L; Moreau, N J

    1997-01-01

    The accumulation of fluoroquinolones (FQs) was studied in a FQ-susceptible laboratory strain of Streptococcus pneumoniae (strain R6). Uptake of FQs was not saturable, was rapidly reversible, and appeared to occur by passive diffusion. In the presence of glucose, which energizes bacteria, the uptake of FQs decreased. Inhibitors of the proton motive force and ATP synthesis increased the uptake of FQs in previously energized bacteria. Similar results were observed with the various FQs tested and may be explained to be a consequence simply of the pH gradient that exists across the cytoplasmic membrane. From a clinical susceptible strain (strain SPn5907) we isolated in vitro on ciprofloxacin an FQ-resistant mutant (strain SPn5929) for which the MICs of hydrophilic molecules were greater than those of hydrophobic molecules, and the mutant was resistant to acriflavine, cetrimide, and ethidium bromide. Strain SPn5929 showed a significantly decreased uptake of ciprofloxacin, and its determinant of resistance to ciprofloxacin was transferred by transformation to susceptible laboratory strain R6 (strain R6tr5929). No mutations in the quinolone resistance-determining regions of the gyrA and parC genes were found. In the presence of arsenate or carbonyl cyanide m-chlorophenylhydrazone, the levels of uptake of ciprofloxacin by the two resistant strains, SPn5929 and R6tr5929, reached the levels of uptake of their susceptible parents. These results suggest an active efflux of ciprofloxacin in strain SPn5929. PMID:9303396

  9. Macrolide resistance in Streptococcus pyogenes isolates from throat infections in the region of Aachen, Germany.

    PubMed

    Brandt, C M; Honscha, M; Truong, N D; Holland, R; Hövener, B; Bryskier, A; Lütticken, R; Reinert, R R

    2001-01-01

    Macrolide-resistance was assessed in 216 consecutive Streptococcus pyogenes isolates from throat infections in the region of Aachen, Germany. Seventeen isolates were resistant to erythromycin: 12 isolates revealed a macrolide (M) phenotype and harbored mefA, and five strains expressed an inducible macrolide-lincosamide-streptogramin B (MLSB) phenotype of which four strains harbored ermA(TR) and one strain contained ermB(AM). Telithromycin (HMR 3647) and quinupristin/dalfopristin remained active particularly against the ermA(TR)-containing S. pyogenes isolates studied. Random amplified polymorphic DNA analysis identified multiple clones among erythromycin-resistant strains, but did not discriminate beyond the emm-type. mefA was present in three isolates either with emm2, emm12, or emm75, and in nine isolates with emm4. All four strains with ermA(TR) contained emm77, and the single strain with ermB(AM) harbored emm1. Despite the relative low rate of macrolide-resistance, these data suggest that at least three different macrolide-resistance determinants are prevalent in Germany and that mefA has spread rapidly into multiple clones of S. pyogenes.

  10. Molecular Basis for Erythromycin Resistance in Group A Streptococcus Isolated From Skin and Soft Tissue Infections

    PubMed Central

    Menon, Thangam

    2015-01-01

    Background In recent years there has been an increase in the use of erythromycin in the treatment of infections caused by bacteria other than Group A Streptococcus (GAS), which has resulted in increased resistance to this antibiotic. Erythromycin and other macrolides are alternative agents for treating GAS infections in patients, who are allergic to penicillin and its derivatives. Aim The main aim of this study was to identify frequency, pattern and genetic determinant of erythromycin resistance among the GAS isolated from skin and soft tissue infections. Materials and Methods A total 100 isolates of GAS were screened for erythromycin resistance by phenotypic and genotypic method. Results The results of the present study showed that 38% isolates were resistant to erythromycin. The iMLS (inducible macrolide-lincosamide-streptogramin) phenotype was predominant (55.26%) followed by M phenotype (26.32%) and cMLS (constitutive macrolide-lincosamide-streptogramin) (18.42%). Conclusion Phenotypic and genotypic analysis showed that the MLSB phenotype with ermB mediated mechanism of resistance was found the most common (76.31%) followed by mefA (20.51%). The ermTR genes was absent in all the isolates. PMID:26672671

  11. Correlation of Serotypes and Genotypes of Macrolide-Resistant Streptococcus agalactiae

    PubMed Central

    Kim, Hyo Youl; Jang, In Ho; Hwang, Gyu Yel; Yoon, Kap Jun

    2005-01-01

    Despite the necessity for studies of group B streptococci (GBS), due to the increase in serious adult infections, the emergence of new serotypes, and the increased resistance to macrolide antibiotics, such studies have been limited in Korea. The primary purpose of the present study was to determine the frequency trends of GBS serotypes, including serotypes VI, VII, and VIII. The final objective was to elucidate the relationship between the genotypes and serotypes of macrolide-resistant GBS isolates from a Korean population. Among 446 isolates of Streptococcus agalactiae, isolated between January 1990 and December 2002 in Korea, the frequency of serotypes were III (36.5%), Ib (22.0%), V (21.1%), Ia (9.6%), VI (4.3%), II (1.8%), VIII (1.3%), IV (1.1%), and VII (0.9%). The resistance rates to erythromycin, by serotype, were 85% (V), 23% (III), 21% (VI), 3% (Ib), and 2% (Ia). Of 135 erythromycin-resistant S. agalactiae, ermB was detected in 105 isolates, mefA in 20 isolates, and ermTR in seven isolates; most type V isolates harbored the ermB gene, Ib type isolates had an equal distribution of resistance genes, type III isolates accounted for 70% of all isolates carrying mefA genes, and one fourth of type VI isolates had mefA genes. PMID:16127771

  12. Meningitis Due to Mixed Infection with Penicillin-Resistant and Penicillin-Susceptible Strains of Streptococcus pneumoniae

    PubMed Central

    Chaves, Fernando; Campelo, Carolina; Sanz, Francisca; Otero, Joaquin R.

    2003-01-01

    Streptococcus pneumoniae is the major cause of bacterial meningitis. We report a case of meningitis due to a mixed infection with two distinct strains of S. pneumoniae: one penicillin-resistant strain of serotype 9V and one penicillin-susceptible strain of serotype 7. The two strains exhibited different pulsed-field gel electrophoresis profiles. PMID:12517910

  13. Comparative genome analysis of high-level penicillin resistance in Streptococcus pneumoniae.

    PubMed

    Tait-Kamradt, Amelia G; Cronan, Melissa; Dougherty, Thomas J

    2009-06-01

    Streptococcus pneumoniae strains with very high levels of penicillin resistance (minimum inhibitory concentration [MIC] >or=8 microg/ml) emerged in the 1990 s. Previous studies have traced the changes in penicillin binding proteins (PBP) that result in decreased penicillin susceptibility, and the role of several PBP genes in high-level resistance. In the present study, we investigated the changes that occurred at the two highest levels of penicillin resistance using NimbleGen's Comparative Genome Sequencing (CGS) technology. DNA from a highly resistant (Pen MIC 16 microg/ml) pneumococcus was used to serially transform the R6 strain to high-level resistance. Four distinct levels of penicillin resistance above the susceptible R6 strain (MIC 0.016 microg/ml) were identified. Using CGS technology, the entire genome sequences of the two highest levels of resistant transformants were examined for changes associated with the resistance phenotypes. At the third level of resistance, changes in PBPs 1a, 2b, and 2x were found, very similar to previous reports. At the fourth resistance level, two additional changes were observed in the R6 transformants. More changes were observed in PBP2x, as well as in peptidoglycan GlcNAc deacetylase (pdgA), which had a missense mutation in the coding region. Genetic transformation with polymerase chain reaction (PCR) products generated from the high-level resistant parent containing either the additional PBP2x or mutant pdgA gene did not increase the MIC of the third-level transformant. Only when both PCR products were simultaneously transformed into the third-level transformant did colonies emerge that were at the highest level of resistance (16-32 microg/ml), equivalent to the highly resistant parent strain. This is the first instance of the involvement of a variant pdgA gene in penicillin resistance. It is also clear from these experiments and the literature that there are multiple paths to the pneumococcus achieving high

  14. Transport of multidrug resistance substrates by the Streptococcus agalactiae hemolysin transporter.

    PubMed

    Gottschalk, Birgit; Bröker, Gerd; Kuhn, Melanie; Aymanns, Simone; Gleich-Theurer, Ute; Spellerberg, Barbara

    2006-08-01

    Streptococcus agalactiae (group B streptococcus [GBS]) causes neonatal sepsis, pneumonia, and meningitis, as well as infections of the bovine udder. The S. agalactiae hemolysin is regarded as an important virulence factor, and hemolysin expression is dependent on the cyl gene cluster. cylA and cylB encode the ATP binding and transmembrane domains of a typical ATP binding cassette (ABC) transporter. The deduced proteins contain the signature sequence of a multidrug resistance (MDR) transporter, and mutation of the genes results in a nonhemolytic and nonpigmented phenotype. To further elucidate the function of the putative transporter, nonpolar deletion mutants of cylA were constructed. These mutants are nonhemolytic and can be complemented by the transporter genes. Wild-type strain and nonhemolytic cylA and cylK deletion mutants were exposed to known substrates of MDR transporters. Mutation of cylA significantly impaired growth in the presence of daunorubicin, doxorubicin, and rhodamine 6G and resulted in a decreased export of doxorubicin from the cells. The mutation of cylK, a gene of unknown function located downstream from cylA, caused a loss of hemolysis but had no effect on the transport of MDR substrates. Furthermore, the hemolytic activity of the wild-type strain was inhibited by reserpine in a dose-dependent manner. We conclude that CylAB closely resembles an ABC-type MDR transporter and propose that the GBS hemolysin molecule represents a natural substrate of the transporter.

  15. Hydrogen Peroxide-Dependent DNA Release and Transfer of Antibiotic Resistance Genes in Streptococcus gordonii ▿

    PubMed Central

    Itzek, Andreas; Zheng, Lanyan; Chen, Zhiyun; Merritt, Justin; Kreth, Jens

    2011-01-01

    Certain oral streptococci produce H2O2 under aerobic growth conditions to inhibit competing species like Streptococcus mutans. Additionally, H2O2 production causes the release of extracellular DNA (eDNA). eDNA can participate in several important functions: biofilm formation and cell-cell aggregation are supported by eDNA, while eDNA can serve as a nutrient and as an antimicrobial agent by chelating essential cations. eDNA contains DNA fragments of a size that has the potential to transfer genomic information. By using Streptococcus gordonii as a model organism for streptococcal H2O2 production, H2O2-dependent eDNA release was further investigated. Under defined growth conditions, the eDNA release process was shown to be entirely dependent on H2O2. Chromosomal DNA damage seems to be the intrinsic signal for the release, although only actively growing cells were proficient eDNA donors. Interestingly, the process of eDNA production was found to be coupled with the induction of the S. gordonii natural competence system. Consequently, the production of H2O2 triggered the transfer of antibiotic resistance genes. These results suggest that H2O2 is potentially much more than a simple toxic metabolic by-product; rather, its production could serve as an important environmental signal that facilitates species evolution by transfer of genetic information and an increase in the mutation rate. PMID:21984796

  16. Efficacy of ceftaroline fosamil against penicillin-sensitive and -resistant streptococcus pneumoniae in an experimental rabbit meningitis model.

    PubMed

    Cottagnoud, P; Cottagnoud, M; Acosta, F; Stucki, A

    2013-10-01

    Ceftaroline is a new cephalosporin with bactericidal activity against resistant Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant Streptococcus pneumoniae, as well as common Gram-negative organisms. This study tested the prodrug, ceftaroline fosamil, against a penicillin-sensitive and a penicillin-resistant strain of S. pneumoniae in an experimental rabbit meningitis model. The penetration of ceftaroline into inflamed meninges was approximately 14%. Ceftaroline fosamil was slightly superior to ceftriaxone against the penicillin-sensitive strain and significantly superior to the combination of ceftriaxone and vancomycin against the penicillin-resistant strain.

  17. Genetic Characterization of Fluoroquinolone-Resistant Streptococcus pneumoniae Strains Isolated during Ciprofloxacin Therapy from a Patient with Bronchiectasis

    PubMed Central

    de la Campa, Adela G.; Ferrandiz, María-José; Tubau, Fe; Pallarés, Román; Manresa, Federico; Liñares, Josefina

    2003-01-01

    Five Spain9V-3 Streptococcus pneumoniae strains were isolated from a patient with bronchiectasis who had received long-term ciprofloxacin therapy. One ciprofloxacin-susceptible strain was isolated before treatment, and four ciprofloxacin-resistant strains were isolated during treatment. The resistant strains were derived from the susceptible strain either by a parC mutation (low-level resistance) or by parC and gyrA mutations (high-level resistance). This study shows that ciprofloxacin therapy in a patient colonized by susceptible S. pneumoniae may select fluoroquinolone-resistant mutants. PMID:12654682

  18. Genetic characterization of fluoroquinolone-resistant Streptococcus pneumoniae strains isolated during ciprofloxacin therapy from a patient with bronchiectasis.

    PubMed

    de la Campa, Adela G; Ferrandiz, María-José; Tubau, Fe; Pallarés, Román; Manresa, Federico; Liñares, Josefina

    2003-04-01

    Five Spain(9V-3) Streptococcus pneumoniae strains were isolated from a patient with bronchiectasis who had received long-term ciprofloxacin therapy. One ciprofloxacin-susceptible strain was isolated before treatment, and four ciprofloxacin-resistant strains were isolated during treatment. The resistant strains were derived from the susceptible strain either by a parC mutation (low-level resistance) or by parC and gyrA mutations (high-level resistance). This study shows that ciprofloxacin therapy in a patient colonized by susceptible S. pneumoniae may select fluoroquinolone-resistant mutants.

  19. Clinical resistance and decreased susceptibility in Streptococcus suis isolates from clinically healthy fattening pigs.

    PubMed

    Callens, Bénédicte F; Haesebrouck, Freddy; Maes, Dominiek; Butaye, Patrick; Dewulf, Jeroen; Boyen, Filip

    2013-04-01

    Streptococcus suis (S. suis) has often been reported as an important swine pathogen and is considered as a new emerging zoonotic agent. Consequently, it is important to be informed on its susceptibility to antimicrobial agents. In the current study, the Minimum Inhibitory Concentration (MIC) population distribution of nine antimicrobial agents has been determined for nasal S. suis strains, isolated from healthy pigs at the end of the fattening period from 50 closed or semiclosed pig herds. The aim of the study was to report resistance based on both clinical breakpoints (clinical resistance percentage) and epidemiological cutoff values (non-wild-type percentage). Non-wild-type percentages were high for tetracycline (98%), lincomycin (92%), tilmicosin (72%), erythromycin (70%), tylosin (66%), and low for florfenicol (0%) and enrofloxacin (0.3%). Clinical resistance percentages were high for tetracycline (95%), erythromycin (66%), tylosin (66%), and low for florfenicol (0.3%) and enrofloxacin (0.3%). For tiamulin, for which no clinical breakpoint is available, 57% of the isolates did not belong to the wild-type population. Clinical resistance and non-wild-type percentages differed substantially for penicillin. Only 1% of the tested S. suis strains was considered as clinically resistant, whereas 47% of the strains showed acquired resistance when epidemiological cutoff values were used. In conclusion, MIC values for penicillin are gradually increasing, compared to previous reports, although pigs infected with strains showing higher MICs may still respond to treatment with penicillin. The high rate of acquired resistance against tiamulin has not been reported before. Results from this study clearly demonstrate that the use of different interpretive criteria contributes to the extent of differences in reported antimicrobial resistance results. The early detection of small changes in the MIC population distribution of isolates, while clinical failure may not yet be

  20. Prevalence and mechanisms of erythromycin resistance in Streptococcus agalactiae from healthy pregnant women.

    PubMed

    Pinheiro, Sandra; Radhouani, Hajer; Coelho, Céline; Gonçalves, Alexandre; Carvalho, Eulália; Carvalho, José António; Ruiz-Larrea, Fernanda; Torres, Carmen; Igrejas, Gilberto; Poeta, Patrícia

    2009-06-01

    We sought to determine the resistance phenotypes for erythromycin and clindamycin and the mechanisms implicated in 93 Streptococcus agalactiae isolates recovered from healthy pregnant women. Susceptibility testing for erythromycin, clindamycin, penicillin, cefotaxime, vancomycin, quinupristin-dalfopristin, choramphenicol, ofloxacin, and meropenen was carried out by disc-diffusion test, and the E-test was also applied for erythromycin and clindamycin. The constitutive MLS(B) resistance (cMLS(B)) and inducible MLS(B) resistance (iMLS(B)) phenotypes, respectively, as well as the M resistance phenotype were determined by the erythromycin-clindamycin double-disc test. The presence of ermA, ermB, ermC, msrA, and mef(A/E) macrolide resistance genes was studied by PCR. Resistance to erythromycin and clindamycin was found in 15% and 9.6% of the isolates, respectively. The resistance phenotypes detected among the 14 erythromycin-resistant isolates were as follows (number of isolates): cMLS(B) (9), iMLS(B) (3), and M (2). The MICs for erythromycin and clindamycin were as follows: cMLS(B) isolates (128-256 and >or=32 mg/L, respectively), iMLS(B) isolates (16-256 and 1 mg/L), and M isolates (2-8 and 1 mg/L). The following combination of genes were detected among isolates with cMLS(B) or iMLS(B) phenotypes: erm(B) (6 isolates), ermA + ermTR (3), ermA + ermB + ermTR (1), and none of these genes (2). The two isolates with M phenotype harbored the mef(A/E), and msrA gene was also found in one of them.

  1. Telithromycin and quinupristin-dalfopristin resistance in clinical isolates of Streptococcus pyogenes: SMART Program 2001 Data.

    PubMed

    Hsueh, Po-Ren; Teng, Lee-Jene; Lee, Chun-Ming; Huang, Wen-Kuei; Wu, Tsu-Lan; Wan, Jen-Hsien; Yang, Dine; Shyr, Jainn-Ming; Chuang, Yin-Ching; Yan, Jing-Jou; Lu, Jang-Jih; Wu, Jiunn-Jong; Ko, Wen-Chien; Chang, Feng-Yee; Yang, Yi-Chueh; Lau, Yeu-Jun; Liu, Yung-Ching; Leu, Hsieh-Shong; Liu, Cheng-Yi; Luh, Kwen-Tay

    2003-07-01

    This study evaluated the current status of antimicrobial resistance in clinical isolates of Streptococcus pyogenes in Taiwan as part of the SMART (Surveillance from Multicenter Antimicrobial Resistance in Taiwan) program. In 2001, 419 different isolates of S. pyogenes, including 275 from respiratory secretions, 87 from wound pus, and 31 from blood, were collected from nine hospitals in different parts of Taiwan. MICs of 23 antimicrobial agents were determined at a central location by the agar dilution method. All of the isolates were susceptible to penicillin (MIC at which 90% of the isolates were inhibited [MIC(90)], resistant), and 5% were not susceptible to clindamycin. Of the 101 erythromycin-resistant isolates, 80.2% exhibited the M phenotype (mefA gene positive), 18.9% exhibited the cMLS (constitutive resistance to macrolides-lincosamides-streptogramin B [MLS]) phenotype (ermB gene positive), and 1% exhibited the iMLS (inducible resistance to MLS) phenotype (ermB gene positive). Fluoroquinolones (sitafloxacin > moxifloxacin > ciprofloxacin = levofloxacin = gatifloxacin > gemifloxacin) demonstrated potent activity against nearly all of the isolates of S. pyogenes tested. Thirty-two isolates (8%) were not susceptible to quinupristin-dalfopristin. Seventeen percent of isolates had telithromycin MICs of >or=1 microg/ml, and all of these isolates exhibited erythromycin MICs of >or=32 microg/ml. The high prevalence of resistance to telithromycin (which is not available in Taiwan) limits its potential use in the treatment of S. pyogenes infections, particularly in areas with high rates of macrolide resistance.

  2. High-efficiency generation of antibiotic-resistant strains of Streptococcus pneumoniae by PCR and transformation.

    PubMed

    Martín-Galiano, Antonio J; de la Campa, Adela G

    2003-04-01

    We designed a method by which to generate antibiotic-resistant strains of Streptococcus pneumoniae at frequencies 4 orders of magnitude greater than the spontaneous mutation rate. The method is based on the natural ability of this organism to be genetically transformed with PCR products carrying sequences homologous to its chromosome. The genes encoding the targets of ciprofloxacin (parC, encoding the ParC subunit of DNA topoisomerase IV), rifampin (rpoB, encoding the beta subunit of RNA polymerase), and streptomycin (rpsL, encoding the S12 ribosomal protein) from susceptible laboratory strain R6 were amplified by PCR and used to transform the same strain. Resistant mutants were obtained with a frequency of 10(-4) to 10(-5), depending on the fidelity of the DNA polymerase used for PCR amplifications. Ciprofloxacin-resistant mutants, for which the MICs were four-to eightfold higher than that for R6, carried a single mutation of a residue in the quinolone resistance-determining region: S79 (change to A, F, or Y) or D83 (change to N or V). Rifampin-resistant strains, for which the MICs were at least 133-fold higher than that for R6, contained a single mutation within cluster I of rpoB: S482 (change to P), Q486 (change to L), D489 (change to V), or H499 (change to L or Y). Streptomycin-resistant mutants, for which the MICs were at least 64-fold higher than that for R6, carried a mutation at either K56 (change to I, R, or T) or K101 (change to E). PCR products obtained from the mutants were able to transform R6 to resistance with high efficiency (>10(4)). This method could be used to efficiently obtain resistant mutants for any drug whose target is known.

  3. High-Efficiency Generation of Antibiotic-Resistant Strains of Streptococcus pneumoniae by PCR and Transformation

    PubMed Central

    Martín-Galiano, Antonio J.; de la Campa, Adela G.

    2003-01-01

    We designed a method by which to generate antibiotic-resistant strains of Streptococcus pneumoniae at frequencies 4 orders of magnitude greater than the spontaneous mutation rate. The method is based on the natural ability of this organism to be genetically transformed with PCR products carrying sequences homologous to its chromosome. The genes encoding the targets of ciprofloxacin (parC, encoding the ParC subunit of DNA topoisomerase IV), rifampin (rpoB, encoding the β subunit of RNA polymerase), and streptomycin (rpsL, encoding the S12 ribosomal protein) from susceptible laboratory strain R6 were amplified by PCR and used to transform the same strain. Resistant mutants were obtained with a frequency of 10−4 to 10−5, depending on the fidelity of the DNA polymerase used for PCR amplifications. Ciprofloxacin-resistant mutants, for which the MICs were four-to eightfold higher than that for R6, carried a single mutation of a residue in the quinolone resistance-determining region: S79 (change to A, F, or Y) or D83 (change to N or V). Rifampin-resistant strains, for which the MICs were at least 133-fold higher than that for R6, contained a single mutation within cluster I of rpoB: S482 (change to P), Q486 (change to L), D489 (change to V), or H499 (change to L or Y). Streptomycin-resistant mutants, for which the MICs were at least 64-fold higher than that for R6, carried a mutation at either K56 (change to I, R, or T) or K101 (change to E). PCR products obtained from the mutants were able to transform R6 to resistance with high efficiency (>104). This method could be used to efficiently obtain resistant mutants for any drug whose target is known. PMID:12654655

  4. [Epidemiological study of levofloxacin-resistant Streptococcus pneumoniae isolated from 2003 through 2006 in Japan].

    PubMed

    Sohma, Maemi; Yokozawa, Ikuyo; Kaneko, Shingaku; Satake, Sachiko

    2009-03-01

    We evaluated the usefulness of WHONET, free software from the World Health Organization (WHO), in a laboratory-based survey analyzing infectious disease, i.e., Streptococcus pneumoniae, and its antimicrobial susceptibility, i.e., to levofloxacin (LVFX), between 2003 and 2006 at 5 hospitals. The percentage of resistant strains (MIC > or = 8 microg/mL) isolated by the Maebashi Red Cross Hospital Laboratory between 2003 and 2005 was 3.8% (26/684 = number of resistant isolates/number of all isolates), significantly higher (p<0.001, Fisher's exact test) than the 0.5% (8/1717) recorded at 4 other hospital laboratories. In 2006 the Maebashi Red Cross Hospital Laboratory percentage of resistant strains was 0.9% (2/221) in the absence of intervention to reduce the percentage of resistant isolates, while that at 4 other hospital laboratories was 1.3% (9/ 717)--a difference not statistically significant (p = 0.574). Of resistant strains, 86% (24/28) came from patients older than 67 years and 71% (20/28) from outpatients or those newly hospitalized 1 or 2 days. Where and when pathogens are isolated are the two priority factors in epidemiological analysis. Superimposing plot of patient residences and isolated times of LVFX-resistant S. pneumoniae strains for each incidences showed no unusual trends in pathogen distribution. Analysis of possible multiple drug resistance for all LVFX-resistant S. pneumoniae isolates, i.e., resistance profile determination, indicated that no strain isolated in any one-month period shared an identical resistance profile, suggesting that the probability of a community outbreak of one specific S. pneumoniae strain is minimal. We did not find possible causes for the high resistance percentage of isolates recorded by the Maebashi Red Cross Hospital Laboratory during 2003-2005, or for the low resistance percentage for strains isolated during 2006. Analysis of our survey indicated that LVFX-resistant S. pneumoniae isolates are still rare in the

  5. Human Monocytes Promote Th1 and Th17 Responses to Streptococcus pneumoniae ▿

    PubMed Central

    Olliver, Marie; Hiew, Jeffni; Mellroth, Peter; Henriques-Normark, Birgitta; Bergman, Peter

    2011-01-01

    Streptococcus pneumoniae is a leading cause of bacterial pneumonia, meningitis, and sepsis in children. Human immunity to pneumococcal infections has been assumed to depend on anticapsular antibodies. However, recent findings from murine models suggest that alternative mechanisms, dependent on T helper cells, are also involved. Although the immunological events in which T helper cells contribute to acquired immunity have been studied in mice, little is known about how these responses are generated in humans. Therefore, we examined bacterial and host factors involved in the induction of Th1 and Th17 responses, using a coculture model of human monocytes and CD4+ T cells. We show that monocytes promote effector cytokine production by memory T helper cells, leading to a mixed Th1/Th17 (gamma interferon [IFN-γ]/interleukin-17 [IL-17]) profile. Both T helper cytokines were triggered by purified pneumococcal peptidoglycan; however, the balance between the two immune effector arms depended on bacterial viability. Accordingly, live pneumococci triggered a Th1-biased response via monocyte production of IL-12p40, whereas heat-killed pneumococci triggered a Th17 response through TLR2 signaling. An increased understanding of human T helper responses is essential for the development of novel pneumococcal vaccines designed to elicit cell-mediated immunity. PMID:21788380

  6. Tracking of chromosome dynamics in live Streptococcus pneumoniae reveals that transcription promotes chromosome segregation.

    PubMed

    Kjos, Morten; Veening, Jan-Willem

    2014-03-01

    Chromosome segregation is an essential part of the bacterial cell cycle but is poorly characterized in oval-shaped streptococci. Using time-lapse fluorescence microscopy and total internal reflection fluorescence microscopy, we have tracked the dynamics of chromosome segregation in live cells of the human pathogen Streptococcus pneumoniae. Our observations show that the chromosome segregation process last for two-thirds of the total cell cycle; the origin region segregates rapidly in the early stages of the cell cycle while nucleoid segregation finishes just before cell division. Previously we have demonstrated that the DNA-binding protein ParB and the condensin SMC promote efficient chromosome segregation, likely by an active mechanism. We now show that in the absence of SMC, cell division can occur over the unsegregated chromosomes. However, neither smc nor parB are essential in S. pneumoniae, suggesting the importance of additional mechanisms. Here we have identified the process of transcription as one of these mechanisms important for chromosome segregation in S. pneumoniae. Transcription inhibitors rifampicin and streptolydigin as well as mutants affected in transcription elongation cause chromosome segregation defects. Together, our results highlight the importance of passive (or indirect) processes such as transcription for chromosome segregation in oval-shaped bacteria.

  7. Resistance to macrolides in Streptococcus pyogenes in France in pediatric patients.

    PubMed

    Bingen, E; Fitoussi, F; Doit, C; Cohen, R; Tanna, A; George, R; Loukil, C; Brahimi, N; Le Thomas, I; Deforche, D

    2000-06-01

    A total of 1,500 recent throat isolates of Streptococcus pyogenes collected between 1996 and 1999 from children throughout France were tested for their susceptibility to erythromycin, azithromycin, josamycin, clindamycin, and streptogramin B. The erythromycin-resistant isolates were further studied for their genetic mechanism of resistance, by means of PCR. The clonality of these strains was also investigated by means of serotyping and ribotyping. In all, 6.2% of the strains were erythromycin resistant, and 3.4 and 2.8% expressed the constitutive MLS(B) and M resistance phenotypes and harbored the ermB and mefA genes, respectively; ermTR was recovered from one isolate which also harbored the ermB gene. Ten serotypes and 8 ribotypes were identified, but we identified 17 strains by combining serotyping with ribotyping. Among the eight ribotypes, the mefA gene was recovered from six clusters, one being predominant, while the ermB gene was recovered from four clusters, of which two were predominant.

  8. Macrolide resistance in Streptococcus pneumoniae isolated from Argentinian pediatric patients suffering from acute otitis media.

    PubMed

    Reijtman, Vanesa; Gagetti, Paula; Faccone, Diego; Fossati, Sofía; Sommerfleck, Patricia; Hernández, Claudia; Bernáldez, Patricia; Lopardo, Horacio; Corso, Alejandra

    2013-01-01

    Macrolide-resistant Streptococcus pneumoniae emerged in Argentina in 1995, representing 26% of invasive infection isolates in children under 5 years old. The objectives of this study were to describe the prevalence of ermB and mefA genes in macrolide-resistant S. pneumoniae isolates from acute otitis media (AOM) and to determine their genetic relatedness. Between May 2009 and August 2010, 126 S. pneumoniae isolates from 324 otherwise healthy children with a first episode of AOM were included. Twenty six of these isolates (20.6%) were resistant to erythromycin. Most frequent serotypes were: 14 (46.2%), 6A (23.1%), 19F (7.7%) and 9V (7.7%). Twenty (76.9%) carried the mefA gene, 5 (19.2%) have the ermB gene, and 1 (3.9%) both ermB + mefA. Ten clonal types were identified, mostly related to Sweden(15A)-25/ST782 (SLV63), CloneB(6A)/ST473 and England(14)-9/ ST9. This is the first study assessing the mechanisms of macrolide resistance in pneumococci isolates from pediatric AOM in Argentina and their genetic relatedness.

  9. Prevalence and mechanism of resistance against macrolides and lincosamides in Streptococcus suis isolates.

    PubMed

    Martel, A; Baele, M; Devriese, L A; Goossens, H; Wisselink, H J; Decostere, A; Haesebrouck, F

    2001-11-26

    Eighty-seven Streptococcus suis isolates recovered in 1999-2000 from diseased pigs, all from different farms, were screened for resistance against macrolide and lincosamide antibiotics by the disk diffusion and agar dilution test and a PCR assay, amplifying the ermB gene and the mefA/E gene. Seventy-one percent of the isolates showed constitutive resistance to macrolide and lincosamide antibiotics (MLS(B)-phenotype). All these isolates were positive for the ermB gene in the PCR, but negative for the mefA/E gene. For all strains minimum inhibitory concentrations (MIC) against five other antimicrobial agents were determined. All strains were susceptible to penicillin. Ninety-nine percent of the isolates were susceptible to enrofloxacin and tiamulin. Eighty-five percent of the strains were resistant to doxycycline. A 540bp fragment of the ermB genes of eight S. suis strains was sequenced and compared with ermB genes of five S. pneumoniae and five S. pyogenes strains of human origin. A 100% homology was found between these fragments in seven S. suis, one S. pneumoniae and three of the S. pyogenes isolates. This study demonstrates that resistance against macrolides, lincosamides and streptogramin B is widespread in S. suis and mediated by ribosome methylation, encoded by the ermB gene.

  10. The MCP-8 gene and its possible association with resistance to Streptococcus agalactiae in tilapia.

    PubMed

    Fu, Gui Hong; Wan, Zi Yi; Xia, Jun Hong; Liu, Feng; Liu, Xiao Jun; Yue, Gen Hua

    2014-09-01

    Mast cell proteases play an important role in the regulation of the immune response. We identified the cDNA of the mast cell protease 8 (MCP-8) gene and analyzed its genomic structure in tilapia. The ORF of the MCP-8 was 768 bp, encoding 255 amino acids. Quantitative real-time PCR revealed that the MCP-8 gene was expressed predominantly in spleen, moderately in liver, blood, brain, gill, intestine, skin, and weakly expressed in kidney, muscle and eye. After a challenge with Streptococcus agalactiae, the gene was induced significantly (p < 0.05) in intestine, kidney, spleen and liver. Furthermore, we identified five single nucleotide polymorphisms (SNPs) in the MCP-8 gene and found that three SNPs were significantly associated (p < 0.05) with resistance against S. agalactiae. However, we found no association between four SNPs and growth traits (p > 0.05). These results suggest that the MCP-8 gene play an important role in the resistance to S. agalactiae in tilapia. The SNP markers in the MCP-8 gene associated with the resistance to the bacterial pathogen may facilitate selection of tilapia resistant to the bacterial disease. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Resistance Genes and Genetic Elements Associated with Antibiotic Resistance in Clinical and Commensal Isolates of Streptococcus salivarius

    PubMed Central

    Chaffanel, Fanny; Charron-Bourgoin, Florence; Libante, Virginie; Leblond-Bourget, Nathalie

    2015-01-01

    The diversity of clinical (n = 92) and oral and digestive commensal (n = 120) isolates of Streptococcus salivarius was analyzed by multilocus sequence typing (MLST). No clustering of clinical or commensal strains can be observed in the phylogenetic tree. Selected strains (92 clinical and 46 commensal strains) were then examined for their susceptibilities to tetracyclines, macrolides, lincosamides, aminoglycosides, and phenicol antibiotics. The presence of resistance genes tet(M), tet(O), erm(A), erm(B), mef(A/E), and catQ and associated genetic elements was investigated by PCR, as was the genetic linkage of resistance genes. High rates of erythromycin and tetracycline resistance were observed among the strains. Clinical strains displayed either the erm(B) (macrolide-lincosamide-streptogramin B [MLSB] phenotype) or mef(A/E) (M phenotype) resistance determinant, whereas almost all the commensal strains harbored the mef(A/E) resistance gene, carried by a macrolide efflux genetic assembly (MEGA) element. A genetic linkage between a macrolide resistance gene and genes of Tn916 was detected in 23 clinical strains and 5 commensal strains, with a predominance of Tn3872 elements (n = 13), followed by Tn6002 (n = 11) and Tn2009 (n = 4) elements. Four strains harboring a mef(A/E) gene were also resistant to chloramphenicol and carried a catQ gene. Sequencing of the genome of one of these strains revealed that these genes colocalized on an IQ-like element, as already described for other viridans group streptococci. ICESt3-related elements were also detected in half of the isolates. This work highlights the potential role of S. salivarius in the spread of antibiotic resistance genes both in the oral sphere and in the gut. PMID:25862227

  12. Resistance Genes and Genetic Elements Associated with Antibiotic Resistance in Clinical and Commensal Isolates of Streptococcus salivarius.

    PubMed

    Chaffanel, Fanny; Charron-Bourgoin, Florence; Libante, Virginie; Leblond-Bourget, Nathalie; Payot, Sophie

    2015-06-15

    The diversity of clinical (n = 92) and oral and digestive commensal (n = 120) isolates of Streptococcus salivarius was analyzed by multilocus sequence typing (MLST). No clustering of clinical or commensal strains can be observed in the phylogenetic tree. Selected strains (92 clinical and 46 commensal strains) were then examined for their susceptibilities to tetracyclines, macrolides, lincosamides, aminoglycosides, and phenicol antibiotics. The presence of resistance genes tet(M), tet(O), erm(A), erm(B), mef(A/E), and catQ and associated genetic elements was investigated by PCR, as was the genetic linkage of resistance genes. High rates of erythromycin and tetracycline resistance were observed among the strains. Clinical strains displayed either the erm(B) (macrolide-lincosamide-streptogramin B [MLSB] phenotype) or mef(A/E) (M phenotype) resistance determinant, whereas almost all the commensal strains harbored the mef(A/E) resistance gene, carried by a macrolide efflux genetic assembly (MEGA) element. A genetic linkage between a macrolide resistance gene and genes of Tn916 was detected in 23 clinical strains and 5 commensal strains, with a predominance of Tn3872 elements (n = 13), followed by Tn6002 (n = 11) and Tn2009 (n = 4) elements. Four strains harboring a mef(A/E) gene were also resistant to chloramphenicol and carried a catQ gene. Sequencing of the genome of one of these strains revealed that these genes colocalized on an IQ-like element, as already described for other viridans group streptococci. ICESt3-related elements were also detected in half of the isolates. This work highlights the potential role of S. salivarius in the spread of antibiotic resistance genes both in the oral sphere and in the gut. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  13. Genetic resistance elements carrying mef subclasses other than mef(A) in Streptococcus pyogenes.

    PubMed

    Del Grosso, Maria; Camilli, Romina; Barbabella, Giada; Blackman Northwood, John; Farrell, David J; Pantosti, Annalisa

    2011-07-01

    In Streptococcus pyogenes, efflux-mediated erythromycin resistance is associated with the mef gene, represented mostly by mef(A), although a small portion of strains carry different mef subclasses. We characterized the composite genetic elements, including mef subclasses other than mef(A), associated with other resistance genes in S. pyogenes isolates. Determination of the genetic elements was performed by PCR mapping. The strains carrying mosaic mef(A/E), in which the 5' region was identical to mef(A) and the 3' region was identical to mef(E), also carried tet(O). The two genes were found enclosed in an element similar to S. pyogenes prophage Φm46.1, designated the Φm46.1-like element. In S. pyogenes strains carrying mef(E) and tet(M), mef(E) was included in a typical mega element, and in some strains, it was physically associated with tet(M) in the composite element Tn2009. S. pyogenes strains carrying mef(I) also carried catQ; the two genes were linked in a fragment representing a portion of the 5216IQ complex of Streptococcus pneumoniae, designated the defective IQ element. In the only isolate carrying a novel mef gene, this was associated with catQ and tet(M) in a genetic element similar to the 5216IQ complex of S. pneumoniae (5216IQ-like complex), suggesting that the novel mef is in fact a variant of mef(I). This study demonstrates that the composite elements containing mef are shared between S. pyogenes and S. pneumoniae and suggests that it is important to distinguish the mef subclass on the basis of the genetic element containing it.

  14. Streptococcus suis in invasive human infections in Poland: clonality and determinants of virulence and antimicrobial resistance.

    PubMed

    Bojarska, A; Molska, E; Janas, K; Skoczyńska, A; Stefaniuk, E; Hryniewicz, W; Sadowy, E

    2016-06-01

    The purpose of this study was to perform an analysis of Streptococcus suis human invasive isolates, collected in Poland by the National Reference Centre for Bacterial Meningitis. Isolates obtained from 21 patients during 2000-2013 were investigated by phenotypic tests, multilocus sequence typing (MLST), analysis of the TR9 locus from the multilocus variable number tandem repeat (VNTR) analysis (MLVA) scheme and pulsed-field gel electrophoresis (PFGE) of SmaI-digested DNA. Determinants of virulence and antimicrobial resistance were detected by polymerase chain reaction (PCR) and analysed by sequencing. All isolates represented sequence type 1 (ST1) and were suggested to be serotype 2. PFGE and analysis of the TR9 locus allowed the discrimination of four and 17 types, respectively. Most of the isolates were haemolysis- and DNase-positive, and around half of them formed biofilm. Genes encoding suilysin, extracellular protein factor, fibronectin-binding protein, muramidase-released protein, surface antigen one, enolase, serum opacity factor and pili were ubiquitous in the studied group, while none of the isolates carried sequences characteristic for the 89K pathogenicity island. All isolates were susceptible to penicillin, cefotaxime, imipenem, moxifloxacin, chloramphenicol, rifampicin, gentamicin, linezolid, vancomycin and daptomycin. Five isolates (24 %) were concomitantly non-susceptible to erythromycin, clindamycin and tetracycline, and harboured the tet(O) and erm(B) genes; for one isolate, lsa(E) and lnu(B) were additionally detected. Streptococcus suis isolated in Poland from human invasive infections belongs to a globally distributed clonal complex of this pathogen, enriched in virulence markers. This is the first report of the lsa(E) and lnu(B) resistance genes in S. suis.

  15. In vitro pharmacodynamic evaluation of garenoxacin against quinolone-resistant Streptococcus pneumoniae.

    PubMed

    Fukuda, Yoshiko; Takahata, Masahiro; Sugiura, Yoko; Shinmura, Yuko; Nomura, Nobuhiko

    2012-02-01

    The bactericidal activity and resistance selectivity of garenoxacin against Streptococcus pneumoniae with mutations in ParC (S79F) or both GyrA (S81F) and ParC (D83Y and K137N) were investigated using in vitro pharmacokinetic models simulating plasma concentrations for a standard clinical regimen [400mg once daily (q.d.)]. The efficacy of garenoxacin was compared with that of levofloxacin (500 mg q.d.) and moxifloxacin (400mg q.d.). Garenoxacin showed excellent bactericidal activity against S. pneumoniae, including quinolone-resistant S. pneumoniae (QRSP), achieving ratios of area under the plasma concentration-time curve over 24h to minimum inhibitory concentration (AUC(0-24)/MIC) ≥ 26.3, without emerging resistant subpopulations. The area above the killing curves was greater and the time to achieve 99.9% killing was shorter for garenoxacin than the corresponding values for levofloxacin and moxifloxacin. No resistant subpopulations and no additional substitution of amino acids in GyrA or ParC emerged following treatment with garenoxacin. On the other hand, in the parC mutant strain, levofloxacin and moxifloxacin treatment caused an increase in the frequency of the resistant population and an additional substitution of amino acids in GyrA (levofloxacin, S81Y/F/C; moxifloxacin, S81Y or E85K). In QRSP with mutations in GyrA and ParC, levofloxacin had no bactericidal activity, whilst the bactericidal activity of moxifloxacin was less than that of garenoxacin; moreover, an additional substitution of amino acids in ParC (S79Y) was noted. In conclusion, garenoxacin corresponding to an oral dose of 400mg showed excellent bactericidal activity against S. pneumoniae, including QRSP, without the emergence of resistant mutants.

  16. In vitro activity of telithromycin against Spanish Streptococcus pneumoniae isolates with characterized macrolide resistance mechanisms.

    PubMed

    Morosini, M I; Cantón, R; Loza, E; Negri, M C; Galán, J C; Almaraz, F; Baquero, F

    2001-09-01

    The susceptibilities to telithromycin of 203 Streptococcus pneumoniae isolates prospectively collected during 1999 and 2000 from 14 different geographical areas in Spain were tested and compared with those to erythromycin A, clindamycin, quinupristin-dalfopristin, penicillin G, cefotaxime, and levofloxacin. Telithromycin was active against 98.9% of isolates (MICs, < or =0.5 microg/ml), with MICs at which 90% of isolates are inhibited being 0.06 microg/ml, irrespective of the resistance genotype. The corresponding values for erythromycin were 61.0% (MICs, < or =0.25 microg/ml) and >64 microg/ml. The erm(B) gene (macrolide-lincosamide-streptogramin B resistance phenotype) was detected in 36.4% (n = 74) of the isolates, which corresponded to 93.6% of erythromycin-intermediate and -resistant isolates, whereas the mef(A) gene (M phenotype [resistance to erythromycin and susceptibility to clindamycin and spiramycin without blunting]) was present in only 2.4% (n = 5) of the isolates. One of the latter isolates also carried erm(B). Interestingly, in one isolate for which the erythromycin MIC was 2 microg/ml, none of these resistance genes could be detected. Erythromycin MICs for S. pneumoniae erm(B)-positive isolates were higher (range, 0.5 to >64 microg/ml) than those for erm(B)- and mef(A)-negative isolates (range, 0.008 to 2 microg/ml). The corresponding values for telithromycin were lower for both groups, with ranges of 0.004 to 1 and 0.002 to 0.06 microg/ml, respectively. The erythromycin MIC was high for a large number of erm(B)-positive isolates, but the telithromycin MIC was low for these isolates. These results indicate the potential usefulness of telithromycin for the treatment of infections caused by erythromycin-susceptible and -resistant S. pneumoniae isolates when macrolides are indicated.

  17. [Nasopharyngeal carriage of Streptococcus pneumoniae in healthy children and multidrug resistance].

    PubMed

    Bayer, Müjgan; Aslan, Gönül; Emekdaş, Gürol; Kuyucu, Necdet; Kanik, Arzu

    2008-04-01

    Nasopharyngeal carriage of Streptococcus pneumoniae plays an important role for the development of invasive disease and the spread of resistant strains within the community. The aims of this study were to determine the carriage rate of nasopharyngeal S. pneumoniae at healthy school children, to search the susceptibility of the strains to various antibiotics and to evaluate the risk factors for nasopharyngeal carriage of penicillin-resistant pneumococci. A total of 1440 healthy children (age range: 6-13 years old) attending to three primary schools which were chosen randomly in Mersin province (Mediterranean region of Turkey) were included to the study between April 2003 to March 2004. The isolation and identification of S. pneumoniae strains from nasopharyngeal samples were performed by conventional culture methods. Antibiotic sensitivity tests were done according to the Clinical Laboratory Standards Institute directions by disk diffusion method, and penisilin MIC values were detected by E-test (AB Biodisk, Solna, Sweden). S.pneumoniae were isolated from 201 (13.9) of the children. The susceptibility rate of the isolates to penicilin was found as 87.1% (n:175), while 12% (n:24) of the strains yielded intermediate and 1% (n:2) yielded high resistance against penicilin. Overall percentages of resistance to trimethoprim-sulfamethoxazole (TMP-SMX) and macrolides were 30% and 4%, respectively. Two out of eight erythromycin (E) resistant strains showed inducible MLS(B) (macrolide, lincosamide and streptogramin B) type while six showed M (due to active efflux system) type of resistance. Resistance to meropenem, vancomycin, ceftriaxone and ciprofloxacin were not detected. Of S. pneumoniae isolates, 20% were found resistant to only one antibiotic (two strains to penicilin; 39 strains to TMP-SMX), 8.9% to two antibiotics (16 strains to penicillin+TMP-SMX; two strains to penicillin+E) and 2.9% to three or more antibiotics (five strains to penicillin+E+TMP-SMX; one strain to

  18. Contribution of Topoisomerase IV and DNA Gyrase Mutations in Streptococcus pneumoniae to Resistance to Novel Fluoroquinolones

    PubMed Central

    Pestova, Ekaterina; Beyer, Rebecca; Cianciotto, Nicholas P.; Noskin, Gary A.; Peterson, Lance R.

    1999-01-01

    In this study, we assessed the activity of ciprofloxacin, levofloxacin, sparfloxacin, and trovafloxacin against clinical isolates of Streptococcus pneumoniae that were resistant to the less-recently developed fluoroquinolones by using defined amino acid substitutions in DNA gyrase and topoisomerase IV. The molecular basis for resistance was assessed by using mutants selected with trovafloxacin, ciprofloxacin, and levofloxacin in vitro. This demonstrated that the primary target of trovafloxacin in S. pneumoniae is the ParC subunit of DNA topoisomerase IV, similar to most other fluoroquinolones. However, first-step mutants bearing the Ser79→Phe/Tyr substitution in topoisomerase IV subunit ParC were susceptible to trovafloxacin with a minimum inhibitory concentration of 0.25 μg/ml, and mutations in the structural genes for both topoisomerase IV subunit ParC (parC) and the DNA gyrase subunit (gyrA) were required to achieve levels of resistance above the breakpoint. The data also suggest that enhanced activity of trovafloxacin against pneumococci is due to a combination of factors that may include reduced efflux of this agent and an enhanced activity against both DNA gyrase and topoisomerase IV. PMID:10428926

  19. Capsular Serotype and Antibiotic Resistance of Streptococcus pneumoniae Isolates in Two Chilean Cities

    PubMed Central

    Inostroza, Jaime; Trucco, Olivia; Prado, Valeria; Vinet, Ana Maria; Retamal, Gloria; Ossa, Gonzalo; Facklam, Richard R.; Sorensen, Ricardo U.

    1998-01-01

    We compared the incidence of nasopharyngeal colonization by Streptococcus pneumoniae, the serotypes causing mucosal and invasive diseases, and the antibiotic resistance of these strains in patients admitted to three large hospitals and children attending day care centers in two Chilean cities (Santiago and Temuco). The populations in both cities were similar in ethnic background, socioeconomic status, family size, and access to medical care. Significant differences in nasopharyngeal colonization rates, in serotypes causing infections, and in antibiotic resistance were found between the two cities. In children 0 to 2 years of age, 42% were colonized with S. pneumoniae in Santiago compared to 14% in Temuco. A total of 41 serotypes were identified in both Chilean cities studied. Six serotypes were found only in Santiago; 14 serotypes were found only in Temuco. Antibiotic-resistant serotypes 6A, 6B, 14, 19F, and 23F were detected only in Santiago. We show that important differences in the incidence of nasopharyngeal carriage, infection, and S. pneumoniae serotypes can exist in similar populations in different areas of the same country. Our findings are relevant for prevention strategies, antibiotic usage, and vaccine design. PMID:9521139

  20. Application of pbp1A PCR in Identification of Penicillin-Resistant Streptococcus pneumoniae

    PubMed Central

    du Plessis, Mignon; Smith, Anthony M.; Klugman, Keith P.

    1999-01-01

    A seminested PCR assay, based on the amplification of the pneumococcal pbp1A gene, was developed for the detection of penicillin resistance in clinical isolates of Streptococcus pneumoniae. The assay was able to differentiate between intermediate (MICs = 0.25 to 0.5 μg/ml) and higher-level (MICs = ≥1 μg/ml) resistance. Two species-specific primers, 1A-1 and 1A-2, which amplified a 1,043-bp region of the pbp1A penicillin-binding region, were used for pneumococcal detection. Two resistance primers, 1A-R1 and 1A-R2, were designed to bind to altered areas of the pbp1A gene which, together with the downstream primer 1A-2, amplify DNA from isolates with penicillin MICs of ≥0.25 and ≥1 μg/ml, respectively. A total of 183 clinical isolates were tested with the pbp1A assay. For 98.3% (180 of 183) of these isolates, the PCR results obtained were in agreement with the MIC data. The positive and negative predictive values of the assay were 100 and 91%, respectively, for detecting strains for which the MICs were ≥0.25 μg/ml and were both 100% for strains for which the MICs were ≥1 μg/ml. PMID:9986824

  1. Spread of Streptococcus pneumoniae Serotype 8-ST63 Multidrug-Resistant Recombinant Clone, Spain

    PubMed Central

    de la Campa, Adela G.; García, Ernesto; Fenoll, Asunción; Calatayud, Laura; Cercenado, Emilia; Pérez-Trallero, Emilio; Bouza, Emilio; Liñares, Josefina

    2014-01-01

    Since 2004, a total of 131 isolates of Streptococcus pneumoniae multidrug-resistant invasive serotype 8 have been detected in Spain. These isolates showed resistance to erythromycin, clindamycin, tetracycline, and ciprofloxacin. All isolates were obtained from adult patients and shared a common genotype (sequence type [ST]63; penicillin-binding protein 1a [pbp1a], pbp2b, and pbp2x gene profiles; ermB and tetM genes; and a ParC-S79F change). Sixty-eight isolates that required a ciprofloxacin MIC ≥16 μg/mL had additional gyrA gene changes. Serotype 8-ST63 pbp2x sequences were identical with those of antimicrobial drug–susceptible serotype 8-ST53 isolates. Serotype 8-ST63 pbp2b sequences were identical with those of the multidrug-resistant Sweden 15A-ST63 clone. Recombination between the capsular locus and flanking regions of an ST53 isolate (donor) and an ST63 pneumococcus (recipient) generated the novel 15A-ST63 clone. One recombination point was upstream of pbp2x and another was within pbp1a. A serotype 8-ST63 clone was identified as a cause of invasive disease in Spain. PMID:25340616

  2. Fluoroquinolones: is there a different mechanism of action and resistance against Streptococcus pneumoniae?

    PubMed

    Harding, I; Simpson, I

    2000-10-01

    Starting in the 1950s, study and elucidation of the biochemical mechanisms of resistance to antibiotics led to the understanding of both the biology of bacteria and the mode of action of antibiotics. This holds true for the relationship between Streptococcus pneumoniae and the fluoroquinolones. A new feature in this approach is the availability of the nearly complete chromosome sequence of this major human pathogen. In S. pneumoniae, resistance appears to be mainly due to mutational alterations in the intracellular targets of the fluoroquinolones, the type II DNA topoisomerase gyrase and topoisomerase IV. Both enzymes appear to be the primary targets of the drugs in this species. Mutations in the quinolone resistance-determining region (QRDR) of the gyrA gene or the parC gene, which encode the A subunits of DNA gyrase and topoisomerase IV respectively, confer resistance to single-step mutants. Mutations in gyrB and parE, which encode the B subunits of DNA gyrase and topo IV, respectively, have also been implicated in the fluoroquinolone resistance of certain mutants obtained in vitro. The antibiotics most affected by a single mutation are those for which the mutation occurs in their preferred target e.g. gyrase for sparfloxacin and gatifloxacin and topo IV for ciprofloxacin and levofloxacin. The activity of all fluoroquinolones is decreased further when two or more mutations are present. Because they possess similar targets of action, there is cross resistance, albeit at various degrees depending on the intrinsic activity of the molecule, among fluoroquinolones. This stresses, once more, the misleading concept of breakpoints for clinical categorization. A second mechanism of resistance, enhanced active efflux of hydrophilic quinolones such as norfioxacin and ciprofloxacin, is mediated by the membrane-associated protein, PmrA (pneumococcal multidrug resistance). This protein is a 12-transmembrane segment proton-dependent multidrug efflux pump of the major

  3. Commensal Streptococci Serve as a Reservoir for β-Lactam Resistance Genes in Streptococcus pneumoniae

    PubMed Central

    Valdórsson, Oskar; Frimodt-Møller, Niels; Hollingshead, Susan; Kilian, Mogens

    2015-01-01

    Streptococcus pneumoniae is a leading cause of pneumonia, meningitis, septicemia, and middle ear infections. The incidence of S. pneumoniae isolates that are not susceptible to penicillin has risen worldwide and may be above 20% in some countries. Beta-lactam antibiotic resistance in pneumococci is associated with significant sequence polymorphism in penicillin-binding proteins (PBPs). Commensal streptococci, especially S. mitis and S. oralis, have been identified as putative donors of mutated gene fragments. However, no studies have compared sequences of the involved pbp genes in large collections of commensal streptococci with those of S. pneumoniae. We therefore investigated the sequence diversity of the transpeptidase region of the three pbp genes, pbp2x, pbp2b, and pbp1a in 107, 96, and 88 susceptible and nonsusceptible strains of commensal streptococci, respectively, at the nucleotide and amino acid levels to determine to what extent homologous recombination between commensal streptococci and S. pneumoniae plays a role in the development of beta-lactam resistance in S. pneumoniae. In contrast to pneumococci, extensive sequence variation in the transpeptidase region of pbp2x, pbp2b, and pbp1a was observed in both susceptible and nonsusceptible strains of commensal streptococci, conceivably reflecting the genetic diversity of the many evolutionary lineages of commensal streptococci combined with the recombination events occurring with intra- and interspecies homologues. Our data support the notion that resistance to beta-lactam antibiotics in pneumococci is due to sequences acquired from commensal Mitis group streptococci, especially S. mitis. However, several amino acid alterations previously linked to beta-lactam resistance in pneumococci appear to represent species signatures of the donor strain rather than being causal of resistance. PMID:25845880

  4. Serotypes and antibiotic resistance in Group B streptococcus isolated from patients at the Maternity Hospital, Kuwait.

    PubMed

    Boswihi, Samar S; Udo, Edet E; Al-Sweih, Noura

    2012-01-01

    A total of 143 group B streptococcus (GBS) isolates collected from mothers at the Maternity Hospital in Kuwait were investigated for their serotypes and antibiotic resistance, and screened by PCR for the carriage of genes for resistance to tetracycline (tetk, tetM, tetL, tetO), erythromycin (ermA, ermB, ermC, ermTR, ermM, mefA, mefE, msrA) and aminoglycosides (aph3, ant4, ant6). All isolates were serotyped using a latex agglutination test. Most of the isolates belonged to serotypes V (38.5 %), III (20.9 %), Ia (7.7 %) and II (11.2 %). Sixteen isolates (11.2 %) were nontypable. All isolates were susceptible to penicillin, ampicillin and cefotaxime (MICs 0.016-0.094 µg ml(-1)) but were resistant to trimethoprim (92.3 %), tetracycline (89.5 %), minocycline (89.5 %), high-level kanamycin (76.9 %), chloramphenicol (30.0 %), erythromycin (12.6 %), clindamycin (7.0 %), high-level streptomycin (3.5 %) and ciprofloxacin (0.7 %). The tetracycline-resistant isolates contained tetM (94.5 %), tetO (3.9 %), tetL (1.6 %) and tetK (0.8 %). The erythromycin-resistant isolates contained ermB (61.1 %), ermTR (38.9 %), ermA (5.5 %), mefA (5.5 %) and mefE (11 %). All high-level kanamycin-resistant isolates contained aph3. One of the high-level streptomycin-resistant isolates contained ant6. Partial DNA sequencing of aph3 revealed sequences with 99 % similarity to aph3 found in Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus and Staphylococcus epidermidis, suggesting that the GBS isolates could have acquired aph3 from other Gram-positive cocci. The high proportion of isolates with resistance to tetracycline, high-level kanamycin and trimethoprim, and the increase in the prevalence of erythromycin resistance, represents an emerging public health concern that needs further surveillance.

  5. Manganese Homeostasis in Group A Streptococcus Is Critical for Resistance to Oxidative Stress and Virulence

    PubMed Central

    Turner, Andrew G.; Ong, Cheryl-lynn Y.; Gillen, Christine M.; Davies, Mark R.; West, Nicholas P.; McEwan, Alastair G.

    2015-01-01

    ABSTRACT Streptococcus pyogenes (group A Streptococcus [GAS]) is an obligate human pathogen responsible for a spectrum of human disease states. Metallobiology of human pathogens is revealing the fundamental role of metals in both nutritional immunity leading to pathogen starvation and metal poisoning of pathogens by innate immune cells. Spy0980 (MntE) is a paralog of the GAS zinc efflux pump CzcD. Through use of an isogenic mntE deletion mutant in the GAS serotype M1T1 strain 5448, we have elucidated that MntE is a manganese-specific efflux pump required for GAS virulence. The 5448ΔmntE mutant had significantly lower survival following infection of human neutrophils than did the 5448 wild type and the complemented mutant (5448ΔmntE::mntE). Manganese homeostasis may provide protection against oxidative stress, explaining the observed ex vivo reduction in virulence. In the presence of manganese and hydrogen peroxide, 5448ΔmntE mutant exhibits significantly lower survival than wild-type 5448 and the complemented mutant. We hypothesize that MntE, by maintaining homeostatic control of cytoplasmic manganese, ensures that the peroxide response repressor PerR is optimally poised to respond to hydrogen peroxide stress. Creation of a 5448ΔmntE-ΔperR double mutant rescued the oxidative stress resistance of the double mutant to wild-type levels in the presence of manganese and hydrogen peroxide. This work elucidates the mechanism for manganese toxicity within GAS and the crucial role of manganese homeostasis in maintaining GAS virulence. PMID:25805729

  6. New Genetic Element Carrying the Erythromycin Resistance Determinant erm(TR) in Streptococcus pneumoniae▿

    PubMed Central

    Camilli, Romina; Del Grosso, Maria; Iannelli, Francesco; Pantosti, Annalisa

    2008-01-01

    erm(A) subclass erm(TR), a common macrolide resistance determinant in Streptococcus pyogenes but quite rare in Streptococcus pneumoniae, was found in a clinical S. pneumoniae isolate (AP200) from Italy. In this isolate, erm(TR) was found included in a genetic element approximately 56 kb in size that did not appear to be conjugative but could be transferred by transformation. An erm(TR)-containing DNA fragment of approximately 10 kb was sequenced and 12 open reading frames (ORFs) were identified. Upstream of erm(TR), a regulatory protein of the TetR family and the two components of an efflux pump of the ABC type were found. Downstream of erm(TR), there were ORFs homologous to a spectinomycin phosphotransferase, transposases, and a relaxase. Since the genomic sequence of S. pyogenes MGAS10750 carrying erm(TR) became available, comparison between the erm(TR)-containing genetic elements in AP200 and in MGAS10750 was performed. The region flanking erm(TR) in MGAS10750 showed identity with AP200 for 10 ORFs out of 12. PCR mapping using primers designed on the sequence of MGAS10750 confirmed that AP200 carries a genetic element similar to that of MGAS10750. In AP200 the genetic element was inserted inside an ORF homologous to spr0790 of S. pneumoniae R6, coding for a type I restriction modification system. Homologies between the insertion sites in AP200 and MGAS10750 consisted of eight conserved nucleotides, of which three were duplicated, likely representing target site duplication. The structure of the erm(TR)-carrying genetic element shows characteristics of a transposon/prophage remnant chimera. In AP200 this genetic element was designated Tn1806. PMID:18070957

  7. Multiple Mutations Modulate the Function of Dihydrofolate Reductase in Trimethoprim-Resistant Streptococcus pneumoniae

    PubMed Central

    Maskell, Jeffrey P.; Sefton, Armine M.; Hall, Lucinda M. C.

    2001-01-01

    Trimethoprim resistance in Streptococcus pneumoniae can be conferred by a single amino acid substitution (I100-L) in dihydrofolate reductase (DHFR), but resistant clinical isolates usually carry multiple DHFR mutations. DHFR genes from five trimethoprim-resistant isolates from the United Kingdom were compared to susceptible isolates and used to transform a susceptible control strain (CP1015). All trimethoprim-resistant isolates and transformants contained the I100-L mutation. The properties of DHFRs from transformants with different combinations of mutations were compared. In a transformant with only the I100-L mutation (R12/T2) and a D92-A mutation also found in the DHFRs of susceptible isolates, the enzyme was much more resistant to trimethoprim inhibition (50% inhibitory concentration [IC50], 4.2 μM) than was the DHFR from strain CP1015 (IC50, 0.09 μM). However, Km values indicated a lower affinity for the enzyme's natural substrates (Km for dihydrofolate [DHF], 3.1 μM for CP1015 and 27.5 μM for R12/T2) and a twofold decrease in the specificity constant. In transformants with additional mutations in the C-terminal portion of the enzyme, Km values for DHF were reduced (9.2 to 15.2 μM), indicating compensation for the lower affinity generated by I100-L. Additional mutations in the N-terminal portion of the enzyme were associated with up to threefold-increased resistance to trimethoprim (IC50 of up to 13.7 μM). It is postulated that carriage of the mutation M53-I—which, like I100-L, corresponds to a trimethoprim binding site in the Escherichia coli DHFR—is responsible for this increase. This study demonstrates that although the I100-L mutation alone may give rise to trimethoprim resistance, additional mutations serve to enhance resistance and modulate the effects of existing mutations on the affinity of DHFR for its natural substrates. PMID:11257022

  8. Telithromycin and Quinupristin-Dalfopristin Resistance in Clinical Isolates of Streptococcus pyogenes: SMART Program 2001 Data

    PubMed Central

    Hsueh, Po-Ren; Teng, Lee-Jene; Lee, Chun-Ming; Huang, Wen-Kuei; Wu, Tsu-Lan; Wan, Jen-Hsien; Yang, Dine; Shyr, Jainn-Ming; Chuang, Yin-Ching; Yan, Jing-Jou; Lu, Jang-Jih; Wu, Jiunn-Jong; Ko, Wen-Chien; Chang, Feng-Yee; Yang, Yi-Chueh; Lau, Yeu-Jun; Liu, Yung-Ching; Leu, Hsieh-Shong; Liu, Cheng-Yi; Luh, Kwen-Tay

    2003-01-01

    This study evaluated the current status of antimicrobial resistance in clinical isolates of Streptococcus pyogenes in Taiwan as part of the SMART (Surveillance from Multicenter Antimicrobial Resistance in Taiwan) program. In 2001, 419 different isolates of S. pyogenes, including 275 from respiratory secretions, 87 from wound pus, and 31 from blood, were collected from nine hospitals in different parts of Taiwan. MICs of 23 antimicrobial agents were determined at a central location by the agar dilution method. All of the isolates were susceptible to penicillin (MIC at which 90% of the isolates were inhibited [MIC90], ≤0.03 μg/ml), cefotaxime (MIC90, ≤0.03 μg/ml), cefepime (MIC90, 0.06 μg/ml), meropenem (MIC90, ≤0.03 μg/ml), moxifloxacin (MIC90, 0.25 μg/ml), vancomycin (MIC90, 0.5 μg/ml), and linezolid (MIC90, 1 μg/ml). Overall, 78% of isolates were not susceptible to erythromycin (54% were intermediate, and 24% were resistant), and 5% were not susceptible to clindamycin. Of the 101 erythromycin-resistant isolates, 80.2% exhibited the M phenotype (mefA gene positive), 18.9% exhibited the cMLS (constitutive resistance to macrolides-lincosamides-streptogramin B [MLS]) phenotype (ermB gene positive), and 1% exhibited the iMLS (inducible resistance to MLS) phenotype (ermB gene positive). Fluoroquinolones (sitafloxacin > moxifloxacin > ciprofloxacin = levofloxacin = gatifloxacin > gemifloxacin) demonstrated potent activity against nearly all of the isolates of S. pyogenes tested. Thirty-two isolates (8%) were not susceptible to quinupristin-dalfopristin. Seventeen percent of isolates had telithromycin MICs of ≥1 μg/ml, and all of these isolates exhibited erythromycin MICs of ≥32 μg/ml. The high prevalence of resistance to telithromycin (which is not available in Taiwan) limits its potential use in the treatment of S. pyogenes infections, particularly in areas with high rates of macrolide resistance. PMID:12821461

  9. The Fitness Cost of Fluoride Resistance for Different Streptococcus mutans Strains in Biofilms.

    PubMed

    Cai, Yanling; Liao, Ying; Brandt, Bernd W; Wei, Xi; Liu, Hongyan; Crielaard, Wim; Van Loveren, Cor; Deng, Dong Mei

    2017-01-01

    The cariogenic bacterium Streptococcus mutans can develop stable resistance to fluoride through chromosomal mutations in vitro. Fluoride-resistant S. mutans has seldom been isolated in clinical settings, despite the wide application of fluoride in oral-care products. One explanation is that the fluoride-resistant S. mutans strains have decreased fitness. However, so far, there has been no conclusive evidence to support this idea. The aim of this study was to investigate the fitness cost of 48-h biofilms of two fluoride-resistant S. mutans strains, UF35 and UA159-FR (UAFR), using the wild-type fluoride-sensitive strain UA159 as a reference. The engineered UF35 strain contains one point mutation, whereas UAFR, selected from NaF-containing agar plates, has multiple chromosomal mutations. All biofilms were formed for 48 h under a constantly neutral pH or a pH-cycling (8 h of neutral pH and 16 h of pH 5.5) condition in the absence of fluoride. The biomass of the biofilms was quantified with a crystal violet assay. The biofilms were also treated with chlorhexidine or solutions at pH 3.0, after which their lactic acid production was quantified. Compared to the UF35 and UA159 biofilms, the biomass of UAFR biofilms was two-four fold higher, and the UAFR biofilms were more resistant to chlorhexidine and low pH in terms of lactic acid production. No difference in biomass and lactic acid production was detected between UF35 and UA159 biofilms. The fluoride resistance of UAFR and UF35 strains in biofilms was further confirmed by treating the biofilms with NaF solutions. The level of NaF resistance of the three biofilms is generally ranked as follows: UAFR > UF35 > UA159. In conclusion, there is indeed a fitness consequence in UAFR, but surprisingly, this fluoride-resistant strain performs better than UF35 and UA159 under the described conditions. In addition, UF35 did not display a reduced fitness; it performed as well as the wild-type fluoride-sensitive strain.

  10. Surveillance of antimicrobial resistance in clinical isolates of Pasteurella multocida and Streptococcus suis from Ontario swine.

    PubMed

    Glass-Kaastra, Shiona K; Pearl, David L; Reid-Smith, Richard J; McEwen, Beverly; Slavic, Durda; Fairles, Jim; McEwen, Scott A

    2014-10-01

    Susceptibility results for Pasteurella multocida and Streptococcus suis isolated from swine clinical samples were obtained from January 1998 to October 2010 from the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, and used to describe variation in antimicrobial resistance (AMR) to 4 drugs of importance in the Ontario swine industry: ampicillin, tetracycline, tiamulin, and trimethoprim-sulfamethoxazole. Four temporal data-analysis options were used: visualization of trends in 12-month rolling averages, logistic-regression modeling, temporal-scan statistics, and a scan with the "What's strange about recent events?" (WSARE) algorithm. The AMR trends varied among the antimicrobial drugs for a single pathogen and between pathogens for a single antimicrobial, suggesting that pathogen-specific AMR surveillance may be preferable to indicator data. The 4 methods provided complementary and, at times, redundant results. The most appropriate combination of analysis methods for surveillance using these data included temporal-scan statistics with a visualization method (rolling-average or predicted-probability plots following logistic-regression models). The WSARE algorithm provided interesting results for quality control and has the potential to detect new resistance patterns; however, missing data created problems for displaying the results in a way that would be meaningful to all surveillance stakeholders.

  11. A study on erm(B)-mediated MLS resistance in Streptococcus pyogenes clinical isolates.

    PubMed

    Rombini, Silvia; Petrelli, Dezemona; Bolli, Elisabetta; Tran, Chi Nhan; Falconi, Maurizio; Di Luca, Maria Chiara; Prenna, Manuela; Ripa, Sandro; Vitali, Luca Agostino

    2011-07-01

    The constitutive or inducible macrolide-lincosamide-streptogramin (MLS) phenotype of 30 erm(B)-positive Streptococcus pyogenes isolates was determined by different methods and under various growth conditions and correlated to the sequence of the 5'-untranslated regions of erm(B). The MLS phenotype of one-third of the isolates could not be classified. In liquid medium, some of these isolates responded to induction only during the logarithmic phase of growth, while others expressed clindamycin resistance even under noninducing conditions. By increasing the growth rate, we observed a shift from a constitutive towards an inducible pattern of resistance. All data were confirmed by analysis of the 23S rRNA methylation level. The erm(B)-5'-untranslated region was 99% similar in sequence. In erm(B)-positive S. pyogenes, the MLS phenotype is strongly influenced by culture conditions and control of its expression does not depend exclusively on the sequence of the erm(B)-5'-untranslated region. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Surveillance of antimicrobial resistance in clinical isolates of Pasteurella multocida and Streptococcus suis from Ontario swine

    PubMed Central

    Glass-Kaastra, Shiona K.; Pearl, David L.; Reid-Smith, Richard J.; McEwen, Beverly; Slavic, Durda; Fairles, Jim; McEwen, Scott A.

    2014-01-01

    Susceptibility results for Pasteurella multocida and Streptococcus suis isolated from swine clinical samples were obtained from January 1998 to October 2010 from the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, and used to describe variation in antimicrobial resistance (AMR) to 4 drugs of importance in the Ontario swine industry: ampicillin, tetracycline, tiamulin, and trimethoprim–sulfamethoxazole. Four temporal data-analysis options were used: visualization of trends in 12-month rolling averages, logistic-regression modeling, temporal-scan statistics, and a scan with the “What’s strange about recent events?” (WSARE) algorithm. The AMR trends varied among the antimicrobial drugs for a single pathogen and between pathogens for a single antimicrobial, suggesting that pathogen-specific AMR surveillance may be preferable to indicator data. The 4 methods provided complementary and, at times, redundant results. The most appropriate combination of analysis methods for surveillance using these data included temporal-scan statistics with a visualization method (rolling-average or predicted-probability plots following logistic-regression models). The WSARE algorithm provided interesting results for quality control and has the potential to detect new resistance patterns; however, missing data created problems for displaying the results in a way that would be meaningful to all surveillance stakeholders. PMID:25355992

  13. Contribution of phosphoglucosamine mutase to the resistance of Streptococcus gordonii DL1 to polymorphonuclear leukocyte killing.

    PubMed

    Yajima, Ayako; Takahashi, Yukihiro; Shimazu, Kisaki; Urano-Tashiro, Yumiko; Uchikawa, Yoshimori; Karibe, Hiroyuki; Konishi, Kiyoshi

    2009-08-01

    Phosphoglucosamine mutase (GlmM; EC 5.4.2.10) catalyzes the interconversion of glucosamine-6-phosphate to glucosamine-1-phosphate, an essential step in the biosynthetic pathway leading to the formation of the peptidoglycan precursor uridine 5'-diphospho-N-acetylglucosamine. We have recently identified the gene (glmM) encoding the enzyme of Streptococcus gordonii, an early colonizer on the human tooth and an important cause of infective endocarditis, and indicated that the glmM mutation in S. gordonii appears to influence bacterial cell growth, morphology, and sensitivity to penicillins. In the present study, we assessed whether the glmM mutation also affects escape from polymorphonuclear leukocyte (PMN)-dependent killing. Although no differences in attachment to human PMNs were observed between the glmM mutant and the wild-type S. gordonii, the glmM mutation resulted in increased sensitivity to PMN-dependent killing. Compared with the wild type, the glmM mutant induced increased superoxide anion production and lysozyme release by PMNs. Moreover, the glmM mutant is more sensitive to lysozyme, indicating that the GlmM may be required for synthesis of firm peptidoglycans for resistance to bacterial cell lysis. These findings suggest that the GlmM contributes to the resistance of S. gordonii to PMN-dependent killing. Enzymes such as GlmM could be novel drug targets for this organism.

  14. Streptococcus sanguinis isolate displaying a phenotype with cross-resistance to several rRNA-targeting agents.

    PubMed

    Mendes, Rodrigo E; Deshpande, Lalitagauri M; Kim, Jihye; Myers, Debra S; Ross, James E; Jones, Ronald N

    2013-08-01

    This study describes a clinical case of a 71-year-old male with a history of ischemic cardiomyopathy after left ventricular assist device (LVAD) endocarditis caused by methicillin-resistant Staphylococcus epidermidis (MRSE) and a rare linezolid-resistant Streptococcus sanguinis strain (MIC, 32 μg/ml). The patient received courses of several antimicrobial agents, including linezolid for 79 days. The S. sanguinis strain had mutations in the 23S rRNA (T2211C, T2406C, G2576T, C2610T) and an amino acid substitution (N56D) in L22 and exhibited cross-resistance to ribosome-targeting agents.

  15. Throat Carriage Rate and Antimicrobial Resistance of Streptococcus pyogenes In Rural Children in Argentina.

    PubMed

    Delpech, Gastón; Sparo, Mónica; Baldaccini, Beatriz; Pourcel, Gisela; Lissarrague, Sabina; García Allende, Leonardo

    2017-03-01

    The aim of this study was to determine the prevalence of asymptomatic carriers of group A β-hemolytic streptococci (GAS) in children living in a rural community and to investigate the association between episodes of acute pharyngitis and carrier status. Throat swabs were collected from September to November 2013 among children 5-13 years of age from a rural community (Maria Ignacia-Vela, Argentina). The phenotypic characterization of isolates was performed by conventional tests. Antimicrobial susceptibility was assayed for penicillin, tetracycline, chloramphenicol, erythromycin, and clindamycin (disk diffusion). The minimum inhibitory concentration was determined for penicillin, cefotaxime, tetracycline, and erythromycin. The carriage of β-hemolytic streptococci was detected in 18.1% of participants, with Streptococcus pyogenes in 18 participants followed by S. dysgalactiae ssp. equisimilis in 5. The highest proportion of GAS was found in 8 to 10-year-old children. No significant association between the number of episodes of acute pharyngitis suffered in the last year and the carrier state was detected (p>0.05). Tetracycline resistance (55.5%) and macrolide-resistant phenotypes (11.1%) were observed. Resistance to penicillin, cefotaxime, or chloramphenicol was not expressed in any streptococcal isolate. The present study demonstrated significant throat carriage of GAS and the presence of group C streptococci (S. dysgalactiae ssp. equisimilis) in an Argentinian rural population. These results point out the need for continuous surveillance of GAS and non-GAS carriage as well as of antimicrobial resistance in highly susceptible populations, such as school-aged rural children. An extended surveillance program including school-aged children from different cities should be considered to estimate the prevalence of GAS carriage in Argentina.

  16. Population Structure, Antimicrobial Resistance, and Mutation Frequencies of Streptococcus pneumoniae Isolates from Cystic Fibrosis Patients

    PubMed Central

    del Campo, Rosa; Morosini, María-Isabel; de la Pedrosa, Elia Gómez-G.; Fenoll, Asunción; Muñoz-Almagro, Carmen; Máiz, Luis; Baquero, Fernando; Cantón, Rafael

    2005-01-01

    Forty-eight Streptococcus pneumoniae isolates recovered from sputum samples from 26 cystic fibrosis (CF) patients attending our CF unit (1995 to 2003) were studied. Mean yearly incidence of isolation was 5.5%, and all were strains recovered from young patients (≤12 years). The isolation was linked to clinical exacerbation in 35% of the cases, but only 27% of these were not accompanied by other CF pathogens. Fifty percent of the patients presented with two to four isolates over the studied period. Pulsed-field gel electrophoresis-SmaI digestion revealed a high heterogeneity (32 pulsotypes among 48 isolates) and the persistence over a 6-month period of a single clone (clone A) in two patients. This clone, presenting a varied multiresistance phenotype, was identified as the Spain23F-1 clone and was also recognized in six other patients, including two out of nine patients from the CF unit of Sant Joan de Dèu Hospital, Barcelona, Spain. In our isolates, 16 different serotypes were recognized, the most frequent being 23F (33.3%), 19F (18.8%), 6A (6.2%), and 6B (6.2%). High overall resistance rates were observed: to penicillin, 73%; to cefotaxime, 33%; to erythromycin, 42%; to tetracycline, 58%; to chloramphenicol, 48%; and to trimethoprim-sulfamethoxazole, 67%. Resistance to fluoroquinolones was not detected. Multiresistance was a common feature (60%). The percentage of S. pneumoniae strains with increased frequencies of mutation to rifampin resistance (≥7.5 × 10−8) was significantly higher (P = 0.02) in CF (60%) than among non-CF (37%) isolates in the same institution (M. I. Morosini et al., Antimicrob. Agents Chemother. 47:1464-1467, 2003). Even though a clear association with acute exacerbations could not be observed, long-term clonal persistence and variability, high frequency of antibiotic resistance, and hypermutability indicate the plasticity for adaptation of S. pneumoniae to the CF lung environment. PMID:15872243

  17. Population structure, antimicrobial resistance, and mutation frequencies of Streptococcus pneumoniae isolates from cystic fibrosis patients.

    PubMed

    del Campo, Rosa; Morosini, María-Isabel; de la Pedrosa, Elia Gómez-G; Fenoll, Asunción; Muñoz-Almagro, Carmen; Máiz, Luis; Baquero, Fernando; Cantón, Rafael

    2005-05-01

    Forty-eight Streptococcus pneumoniae isolates recovered from sputum samples from 26 cystic fibrosis (CF) patients attending our CF unit (1995 to 2003) were studied. Mean yearly incidence of isolation was 5.5%, and all were strains recovered from young patients (< or = 12 years). The isolation was linked to clinical exacerbation in 35% of the cases, but only 27% of these were not accompanied by other CF pathogens. Fifty percent of the patients presented with two to four isolates over the studied period. Pulsed-field gel electrophoresis-SmaI digestion revealed a high heterogeneity (32 pulsotypes among 48 isolates) and the persistence over a 6-month period of a single clone (clone A) in two patients. This clone, presenting a varied multiresistance phenotype, was identified as the Spain23F-1 clone and was also recognized in six other patients, including two out of nine patients from the CF unit of Sant Joan de Deu Hospital, Barcelona, Spain. In our isolates, 16 different serotypes were recognized, the most frequent being 23F (33.3%), 19F (18.8%), 6A (6.2%), and 6B (6.2%). High overall resistance rates were observed: to penicillin, 73%; to cefotaxime, 33%; to erythromycin, 42%; to tetracycline, 58%; to chloramphenicol, 48%; and to trimethoprim-sulfamethoxazole, 67%. Resistance to fluoroquinolones was not detected. Multiresistance was a common feature (60%). The percentage of S. pneumoniae strains with increased frequencies of mutation to rifampin resistance (> or = 7.5 x 10(-8)) was significantly higher (P = 0.02) in CF (60%) than among non-CF (37%) isolates in the same institution (M. I. Morosini et al., Antimicrob. Agents Chemother. 47:1464-1467, 2003). Even though a clear association with acute exacerbations could not be observed, long-term clonal persistence and variability, high frequency of antibiotic resistance, and hypermutability indicate the plasticity for adaptation of S. pneumoniae to the CF lung environment.

  18. Multiple mutations and increased RNA expression in tetracycline-resistant Streptococcus pneumoniae as determined by genome-wide DNA and mRNA sequencing

    PubMed Central

    Lupien, Andréanne; Gingras, Hélène; Bergeron, Michel G.; Leprohon, Philippe; Ouellette, Marc

    2015-01-01

    Objectives The objective of this study was to characterize chromosomal mutations associated with resistance to tetracycline in Streptococcus pneumoniae. Methods Chronological appearance of mutations in two S. pneumoniae R6 mutants (R6M1TC-5 and R6M2TC-4) selected for resistance to tetracycline was determined by next-generation sequencing. A role for the mutations identified was confirmed by reconstructing resistance to tetracycline in a S. pneumoniae R6 WT background. RNA sequencing was performed on R6M1TC-5 and R6M2TC-4 and the relative expression of genes was reported according to R6. Differentially expressed genes were classified according to their ontology. Results WGS of R6M1TC-5 and R6M2TC-4 revealed mutations in the gene rpsJ coding for the ribosomal protein S10 and in the promoter region and coding sequences of the ABC genes patA and patB. These cells were cross-resistant to ciprofloxacin. Resistance reconstruction confirmed a role in resistance for the mutations in rpsJ and patA. Overexpression of the ABC transporter PatA/PatB or mutations in the coding sequence of patA contributed to resistance to tetracycline, ciprofloxacin and ethidium bromide, and was associated with a decreased accumulation of [3H]tetracycline. Comparative transcriptome profiling of the resistant mutants further revealed that, in addition to the overexpression of patA and patB, several genes of the thiamine biosynthesis and salvage pathway were increased in the two mutants, but also in clinical isolates resistant to tetracycline. This overexpression most likely contributes to the tetracycline resistance phenotype. Conclusions The combination of genomic and transcriptomic analysis coupled to functional studies has allowed the discovery of novel tetracycline resistance mutations in S. pneumoniae. PMID:25862682

  19. [Clinical characteristics and antimicrobial resistance of invasive group A β-hemolytic streptococcus infection in children].

    PubMed

    Fan, Jiemin; Dong, Lin; Chen, Zhaoxing; Bei, Dandan

    2014-01-01

    Group A β-hemolytic streptococcus (GAS) or Streptococcus pyogenes may be encountered in diverse clinical situations in children. A rising incidence of invasive group A streptococcus (IGAS) infections has been noted in children in the past three decades. The aim of this study was to summarize the clinical characteristics and antimicrobial resistance of IGAS in children, and to raise the level of diagnosis and treatment of this infection. The clinical data from 19 cases of IGAS younger than 14 years old seen from January 2004 to December 2011 treated in the authors' hospital were analyzed. IGAS infections are defined as the isolation of GAS from a normally sterile site in patients. The 19 cases were identified as IGAS infections, among whom 15 were male and 4 were female, and the ratio of them was 3.75. The age ranged from 1 day to 14 years, with a median age of 4 years. The course of disease was 4 h-10 days. The average length of stay was 12.2 days. In 13 cases the episodes of the infection occurred in winter and spring. In 18 cases the infection was community-acquired. Overall, 10 cases had neck or foot dorsum abscess, four cases had purulent peritonitis, and 3 cases were diagnosed as streptococcal toxic shock syndrome (STSS) complicated with empyema, pyopneumothorax occurred in 1 case and neonatal septicemia in another. Three cases had an underlying disease, including 2 cases wounded in a car accident and 1 case of congenital esophageal atresia and tracheoesophageal fistula. Before the isolation of GAS, 5 cases had stayed in ICUs, the length of ICU stay was 1-32 days, 4 cases had received intubation and mechanical ventilation, the ventilation time was 8 h-24 days, 2 cases had received major surgery; 5 cases had other pathogen coinfection, including 4 cases of abdominal pus at the same time and Escherichia coli was isolated, and 1 case had parainfluenza virus type I coinfection. Peripheral blood leucocyte increased in 18 cases, one case dropped off. The C

  20. Streptolysin O and NAD-glycohydrolase prevent phagolysosome acidification and promote group A Streptococcus survival in macrophages.

    PubMed

    Bastiat-Sempe, Benedicte; Love, John F; Lomayesva, Natalie; Wessels, Michael R

    2014-09-16

    Group A Streptococcus (GAS, Streptococcus pyogenes) is an ongoing threat to human health as the agent of streptococcal pharyngitis, skin and soft tissue infections, and life-threatening conditions such as necrotizing fasciitis and streptococcal toxic shock syndrome. In animal models of infection, macrophages have been shown to contribute to host defense against GAS infection. However, as GAS can resist killing by macrophages in vitro and induce macrophage cell death, it has been suggested that GAS intracellular survival in macrophages may enable persistent infection. Using isogenic mutants, we now show that the GAS pore-forming toxin streptolysin O (SLO) and its cotoxin NAD-glycohydrolase (NADase) mediate GAS intracellular survival and cytotoxicity for macrophages. Unexpectedly, the two toxins did not inhibit fusion of GAS-containing phagosomes with lysosomes but rather prevented phagolysosome acidification. SLO served two essential functions, poration of the phagolysosomal membrane and translocation of NADase into the macrophage cytosol, both of which were necessary for maximal GAS intracellular survival. Whereas NADase delivery to epithelial cells is mediated by SLO secreted from GAS bound to the cell surface, in macrophages, the source of SLO and NADase is GAS contained within phagolysosomes. We found that transfer of NADase from the phagolysosome to the macrophage cytosol occurs not by simple diffusion through SLO pores but rather by a specific translocation mechanism that requires the N-terminal translocation domain of NADase. These results illuminate the mechanisms through which SLO and NADase enable GAS to defeat macrophage-mediated killing and provide new insight into the virulence of a major human pathogen. Macrophages constitute an important element of the innate immune response to mucosal pathogens. They ingest and kill microbes by phagocytosis and secrete inflammatory cytokines to recruit and activate other effector cells. Group A Streptococcus (GAS

  1. Activity of telithromycin against penicillin-resistant Streptococcus pneumoniae isolates recovered from French children with invasive and noninvasive infections.

    PubMed

    Bingen, Edouard; Doit, Catherine; Loukil, Chawki; Brahimi, Naima; Bidet, Philippe; Deforche, Dominique; Geslin, Pierre

    2003-07-01

    We compared the activities of telithromycin, erythromycin, azithromycin, josamycin, penicillin G, amoxicillin, cefpodoxime, and ceftriaxone against invasive and noninvasive non-penicillin-susceptible Streptococcus pneumoniae isolates recovered from children. Of the 186 isolates tested, 89% were positive for erm(B) by PCR. Telithromycin had the lowest MICs, with MICs at which 90% of the isolates tested are inhibited of 0.032 and 0.25 micro g/ml for erythromycin-sensitive and -resistant isolates, respectively.

  2. Streptococcus pyogenes Pharyngeal Isolates with Reduced Susceptibility to Ciprofloxacin in Spain: Mechanisms of Resistance and Clonal Diversity

    PubMed Central

    Albertí, Sebastián; Cortés, Guadalupe; García-Rey, Cesar; Rubio, Carmen; Baquero, Fernando; García-Rodríguez, José Ángel; Bouza, Emilio; Aguilar, Lorenzo

    2005-01-01

    A survey of emm gene sequences and an analysis of the pulsed-field electrophoretic profiles of 30 Streptococcus pyogenes isolates with reduced susceptibilities to ciprofloxacin detected the prevalence of isolates with emm type 6 and considerable genetic diversity among isolates. The mechanism of ciprofloxacin resistance in these isolates was based on point mutations in topoisomerase IV subunit C encoded by parC, mainly replacement of serine-79 by alanine. PMID:15616324

  3. Evaluation of disk approximation and single-well broth tests for detection of inducible clindamycin resistance in Streptococcus pneumoniae.

    PubMed

    Jorgensen, James H; McElmeel, M Leticia; Fulcher, Letitia C; McGee, Lesley; Glennen, Anita

    2011-09-01

    This study evaluated an agar disk diffusion D-zone test and an erythromycin-clindamycin (ERY + CLI) single-well broth test for inducible CLI resistance in Streptococcus pneumoniae. The standard CLSI disk approximation test and a single-well combination test incorporating 1 plus 0.5 μg/ml ERY + CLI detected >96% of isolates containing the ermB determinant.

  4. Streptococcus pneumoniae, le transformiste.

    PubMed

    Johnston, Calum; Campo, Nathalie; Bergé, Matthieu J; Polard, Patrice; Claverys, Jean-Pierre

    2014-03-01

    Streptococcus pneumoniae (the pneumococcus) is an important human pathogen. Natural genetic transformation, which was discovered in this species, involves internalization of exogenous single-stranded DNA and its incorporation into the chromosome. It allows acquisition of pathogenicity islands and antibiotic resistance and promotes vaccine escape via capsule switching. This opinion article discusses how recent advances regarding several facets of pneumococcal transformation support the view that the process has evolved to maximize plasticity potential in this species, making the pneumococcus le transformiste of the bacterial kingdom and providing an advantage in the constant struggle between this pathogen and its host.

  5. Controlled laboratory challenge demonstrates substantial additive genetic variation in resistance to Streptococcus iniae in Nile tilapia

    USDA-ARS?s Scientific Manuscript database

    Streptococcus iniae is an etiologic agent of streptococcal disease in tilapia and is one of several Streptococcus spp. that negatively impact worldwide tilapia production. Methods for the prevention and control of S. iniae include vaccines, management strategies, and antibiotics. An alternative and ...

  6. Capsular serotype and antibiotic resistance of Streptococcus pneumoniae isolates in Malaysia.

    PubMed

    Le, Cheng-Foh; Palanisamy, Navindra Kumari; Mohd Yusof, Mohd Yasim; Sekaran, Shamala Devi

    2011-01-01

    Streptococcus pneumoniae is a major causative agent of severe infections, including sepsis, pneumonia, meningitis, and otitis media, that has since become a major public health concern. In this study, the serotypes distribution of pneumococcal isolates was investigated to predict the efficacy of the 7-valent pneumococcal conjugate vaccine (PCV7) among the Malaysian populations. A total of 151 clinical isolates were serotyped using multiplex PCR assays. Out of them, there were 21.2% penicillin-resistant, 29.1% penicillin-intermediate, and 49.7% penicillin-susceptible S. pneumoniae strains. Serotypes detected among the Malaysian isolates were 1, 3, 10A, 11A/11D, 12F/12A, 14, 15A, 15B/15C, 16F, 18C/18B/18A/18F, 19A, 19F, 23F, 35B, 35F/47F, 6A/6B, 7C/7B/40, 7F/7A, 9V/9A, and 34. Serotype 19F and 23F were the two most prevalent serotypes detected. Serotypes are highly associated with invasiveness of isolates (p = 0.001) and penicillin susceptibility (p<0.001). Serotype 19F was observed to have increased resistance against penicillin while serotype 19A has high invasive tendency. Age of patients was an important factor underlying the pneumococcal serotypes (p = 0.03) and clinical sites of infections (p<0.001). High prevalence of pneumococcal isolates were detected among children <5 years old at nasopharyngeal sites while elderly adults ≥60 years old were at increased risk for pneumococcal bacteremia. Current study revealed that a number of serotypes, especially those associated with high penicillin resistance, have been formulated in the PCV7. Therefore, the protections expected from the routine use of PCV7 would be encouraging for the Malaysian. However, it is not possible to predict serotypes that might become predominant in the future and hence continued surveillance of circulating serotypes will be needed.

  7. Multidrug Resistance in Non-PCV13 Serotypes of Streptococcus pneumoniae in Northern Japan, 2014.

    PubMed

    Kawaguchiya, Mitsuyo; Urushibara, Noriko; Kobayashi, Nobumichi

    2017-03-01

    Since the implementation of routine PCV13 immunization in Japan, nonvaccine serotypes (NVTs) have been increasing among clinical isolates of Streptococcus pneumoniae. In this study, susceptibility to 18 antibiotics was tested for all the 231 isolates with NVTs, which were collected from children <16 years of age in northern Japan in 2014 (July-November). High resistance rates were observed for macrolides (>90.9%), tetracycline (91.3%), and clindamycin (75.3%), while penicillin (PEN) nonsusceptibility (PNSP; MIC ≥0.12 μg/ml) was detected in 42.9% of the pneumococci [39.4%; PEN-intermediate S. pneumoniae (PISP), 3.5%; PEN-resistant S. pneumoniae (PRSP)]. All serotype 15A isolates were PRSP (MIC, ≥2 μg/ml) or PISP, and PNSP was prevalent in also serotypes 23A (96.9%), 6C (41%), and 35B (33.3%). Overall, 42.0% of the isolates showed multidrug resistance (MDR). Sequence types (STs) determined for 20 PNSP isolates with NVTs were ST63 (15A), STs 242 or 5832 (6C), STs 338 or 5242 (23A), and ST558 (35B). All the PNSP isolates possessed tet(M), and erm(B) or mefA(A/E), and 70% of them were gPRSP having three altered genes pbp1a, pbp2x, and pbp2b. Among alterations in transpeptidase-coding region of penicillin-binding proteins (PBPs), two substitutions of T371S in the STMK motif and TSQF574-577NTGY in PBP1a were common to all PRSP isolates. The present study showed the spread of PNSP in NVTs 15A, 23A, 6C, and 35B, and the emergence of the MDR international clone Sweden(15A)-ST63 in northern Japan.

  8. Oxacillin disk diffusion testing for the prediction of penicillin resistance in Streptococcus pneumoniae.

    PubMed

    Horna, Gertrudis; Molero, María L; Benites, Liliana; Roman, Sigri; Carbajal, Luz; Mercado, Erik; Castillo, María E; Zerpa, Rito; Chaparro, Eduardo; Hernandez, Roger; Silva, Wilda; Campos, Francisco; Saenz, Andy; Reyes, Isabel; Villalobos, Alex; Ochoa, Theresa J

    2016-08-01

    Objective To 1) describe the correlation between the zones of inhibition in 1-µg oxacillin disk diffusion (ODD) tests and penicillin and ceftriaxone minimum inhibitory concentrations (MICs) of meningeal and non-meningeal strains of Streptococcus pneumoniae and 2) evaluate the usefulness of the ODD test as a predictor of susceptibility to penicillin in S. pneumoniae and as a quick and cost-effective method easily implemented in a routine clinical laboratory setting. Methods S. pneumoniae isolates from healthy nasopharyngeal carriers less than 2 years old, obtained in a multicentric cross-sectional study conducted in various Peruvian hospitals and health centers from 2007 to 2009, were analyzed. Using Clinical and Laboratory Standards Institute (CLSI) breakpoints, the correlation between the zones of inhibition of the ODD test and the MICs of penicillin and ceftriaxone was determined. Results Of the 571 S. pneumoniae isolates, 314 (55%) showed resistance to penicillin (MIC ≥ 0.12 µg/mL) and 124 (21.7%) showed resistance to ceftriaxone (MIC ≥ 1 µg/mL). Comparison of the ODD test zones of inhibition and the penicillin MICs, using the CLSI meningeal breakpoints, showed good correlation (Cohen's kappa coefficient = 0.8239). Conclusions There was good correlation between ODD zones of inhibition and penicillin meningeal breakpoints but weak correlation between the ODD results and non-meningeal breakpoints for both penicillin and ceftriaxone. Therefore, the ODD test appears to be a useful tool for predicting penicillin resistance in cases of meningeal strains of S. pneumoniae, particularly in low- and middle- income countries, where MIC determination is not routinely available.

  9. Evidence of Clonal Dissemination of Multidrug-Resistant Streptococcus pneumoniae in Hong Kong

    PubMed Central

    Ip, Margaret; Lyon, Donald J.; Yung, Raymond W. H.; Chan, Colin; Cheng, Augustine F. B.

    1999-01-01

    The relationship between the phenotypic and genotypic characteristics of 105 penicillin-intermediate or -resistant Streptococcus pneumoniae isolates saved during 1994 to 1997 at the Prince of Wales Hospital and Pamela Youde Nethersole Eastern Hospital, Hong Kong, was studied. The pbp genes for penicillin-binding proteins 1a, 2b, and 2x for each isolate were amplified by PCR, and the products were digested with restriction enzymes HinfI and AluI. A combination of the pulsed-field gel electrophoresis (PFGE) profiles, pbp fingerprints, and phenotypic characteristics of capsular types and antibiograms enabled these isolates to be divided into four major groups. Seventy-four percent (78 of 105) of the strains, belonging to serotypes 23F, 19F, and 14, showed indistinguishable pbp fingerprint patterns (group A1, 1-1-1, 1-1-1), with PFGE patterns belonging to group A and its subtypes, suggesting that these strains were closely related. Eighty-three percent (65 of 78) of these isolates were also resistant to tetracycline, erythromycin, chloramphenicol, and trimethoprim. The type 23F isolates were indistinguishable from representative strains of the Spanish 23F clone by these molecular methods, indicating that these strains may be variants of the Spanish 23F clone. Serotype 6B accounted for 19% (20 of 105) of the isolates with reduced penicillin susceptibility and was made up of variants belonging to four different pbp fingerprint groups with the PFGE pattern group B, the predominant group being indistinguishable from that of the Spanish 6B clone. Other PFGE and fingerprint groups were mainly obtained from penicillin-susceptible strains of various serotypes. The results suggest that the rapid emergence of drug-resistant S. pneumoniae in Hong Kong has been due to the rapid dissemination of several successful clones. PMID:10449461

  10. Molecular resistance mechanisms of macrolide-resistant invasive Streptococcus pneumoniae isolates from Alaska, 1986 to 2010.

    PubMed

    Rudolph, Karen; Bulkow, Lisa; Bruce, Michael; Zulz, Tammy; Reasonover, Alisa; Harker-Jones, Marcella; Hurlburt, Debby; Hennessy, Thomas

    2013-11-01

    The rapid emergence of antibiotic-resistant pneumococcal strains has reduced treatment options. The aim of this study was to determine antimicrobial susceptibilities, serotype distributions, and molecular resistance mechanisms among macrolide-resistant invasive pneumococcal isolates in Alaska from 1986 to 2010. We identified cases of invasive pneumococcal disease in Alaska from 1986 to 2010 through statewide population-based laboratory surveillance. All invasive pneumococcal isolates submitted to the Arctic Investigations Program laboratory were confirmed by standard microbiological methods and serotyped by slide agglutination and the Quellung reaction. MICs were determined by the broth microdilution method, and macrolide-resistant genotypes were determined by multiplex PCR. Among 2,923 invasive pneumococcal isolates recovered from 1986 to 2010, 270 (9.2%) were nonsusceptible to erythromycin; 177 (66%) erythromycin-nonsusceptible isolates demonstrated coresistance to penicillin, and 167 (62%) were multidrug resistant. The most frequent serotypes among the macrolide-resistant isolates were serotypes 6B (23.3%), 14 (20.7%), 19A (16.7%), 9V (8.9%), 19F (6.3%), 6A (5.6%), and 23F (4.8%). mef and erm(B) genes were detected in 207 (77%) and 32 (12%) of the isolates, respectively. Nineteen (7%) of the erythromycin-nonsusceptible isolates contained both mef and erm(B) genotypes; 15 were of serotype 19A. There was significant year-to-year variation in the proportion of isolates that were nonsusceptible to erythromycin (P < 0.001). Macrolide resistance among pneumococcal isolates from Alaska is mediated predominantly by mef genes, and this has not changed significantly over time. However, there was a statistically significant increase in the proportion of isolates that possess both erm(B) and mef, primarily due to serotype 19A isolates.

  11. Antibiotic susceptibility in Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes in Pakistan: a review of results from the Survey of Antibiotic Resistance (SOAR) 2002-15.

    PubMed

    Zafar, A; Hasan, R; Nizamuddin, S; Mahmood, N; Mukhtar, S; Ali, F; Morrissey, I; Barker, K; Torumkuney, D

    2016-05-01

    To investigate changes in the antibiotic susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes from the Survey of Antibiotic Resistance (SOAR) in community-acquired respiratory tract infections (CA-RTIs) between 2002 and 2015 in Pakistan. This is a review based on previously published studies from 2002-03, 2004-06 and 2007-09 and also new data from 2014-15. Susceptibility was determined by Etest(®) or disc diffusion according to CLSI and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. A total of 706 isolates from CA-RTIs comprising 381 S. pneumoniae, 230 H. influenzae and 95 S. pyogenes were collected between 2002 and 2015 and tested against a range of antibiotics. Antibiotic resistance in S. pneumoniae rose steeply from 2002 to 2009, with isolates non-susceptible to penicillin and macrolides increasing from 10% to 34.1% and from 13%-14% to 29.7%, respectively. Susceptibility to amoxicillin/clavulanic acid (and by inference amoxicillin) remained between 99.4% and 100% from 2002 to 2015. Over the years, the prevalence of susceptibility to cefuroxime was 98%-100% among S. pneumoniae. Resistance in S. pneumoniae to some older antibiotics between 2007 and 2009 was high (86.8% for trimethoprim/sulfamethoxazole and 57.2% for tetracycline). Between 2002 and 2015, ampicillin resistance (β-lactamase-positive strains) among H. influenzae has remained low (between 2.6% and 3.2%) and almost unchanged over the years (H. influenzae was not tested during 2004-06). For S. pyogenes isolates, macrolide resistance reached 22%; however, susceptibility to penicillin, amoxicillin/clavulanic acid and cefuroxime remained stable at 100%. In S. pneumoniae from Pakistan, there has been a clear reduction in susceptibility to key antibiotics since 2002, but not to amoxicillin/clavulanic acid (amoxicillin) or cefuroxime. However, susceptibility in H. influenzae has remained stable. Local antibiotic susceptibility/resistance data are essential to

  12. Evaluation of resistance mechanisms and serotype and genotype distributions of macrolide-resistant strains in clinical isolates of Streptococcus pneumoniae [corrected] in Aydın, Turkey.

    PubMed

    Telli, Murat; Eyigör, Mete; Gültekin, Berna; Aydın, Neriman

    2011-10-01

    Macrolide resistance mechanisms in 89 Streptococcus pneumoniae strains isolated from several clinical samples between February 2007 and May 2009 were investigated. Erythromycin resistance was noted in 35 (40%) S. pneumoniae strains. In these strains, the most frequent resistance phenotype was cMLS(B) (74%), and the most frequent resistance genotype was ermB (82%). Both ermB and mefA genes were positive in 20% of macrolide-resistant strains. While no resistance to vancomycin, linezolid and telithromycin was noted in 89 S. pneumoniae strains, 12 (13%) strains were penicillin resistant, 26 (30%) strains were clindamycin resistant, 35 (40%) were azithromycin resistant, 32 (36%) strains were tetracycline resistant, and 1 (1%) strain was levofloxacin resistant. The serotype distribution of 35 macrolide-resistant S. pneumoniae strains revealed that the most frequent serotype was serogroup 19 (45%). Multidrug resistance was present in 19 (86%) of 22 strains carrying only the ermB resistance gene. No clonal dissemination was noted in the macrolide-resistant pneumococcal strains. These findings suggest that macrolide resistance rates, resistance phenotype and genotype, as well as resistant serotypes of S. pneumoniae strains should be continuously monitored in our country.

  13. Phenotypes and genotypes of erythromycin-resistant Streptococcus pyogenes strains in Italy and heterogeneity of inducibly resistant strains.

    PubMed

    Giovanetti, E; Montanari, M P; Mingoia, M; Varaldo, P E

    1999-08-01

    A total of 387 clinical strains of erythromycin-resistant (MIC, >/=1 microg/ml) Streptococcus pyogenes, all isolated in Italian laboratories from 1995 to 1998, were examined. By the erythromycin-clindamycin double-disk test, 203 (52.5%) strains were assigned to the recently described M phenotype, 120 (31.0%) were assigned to the inducible macrolide, lincosamide, and streptogramin B resistance (iMLS) phenotype, and 64 (16.5%) were assigned to the constitutive MLS resistance (cMLS) phenotype. The inducible character of the resistance of the iMLS strains was confirmed by comparing the clindamycin MICs determined under normal testing conditions and those determined after induction by pregrowth in 0.05 microg of erythromycin per ml. The MICs of erythromycin, clarithromycin, azithromycin, josamycin, spiramycin, and the ketolide HMR3004 were then determined and compared. Homogeneous susceptibility patterns were observed for the isolates of the cMLS phenotype (for all but one of the strains, HMR3004 MICs were 0.5 to 8 microg/ml and the MICs of the other drugs were >128 microg/ml) and those of the M phenotype (resistance only to the 14- and 15-membered macrolides was recorded, with MICs of 2 to 32 microg/ml). Conversely, heterogeneous susceptibility patterns were observed in the isolates of the iMLS phenotype, which were subdivided into three distinct subtypes designated iMLS-A, iMLS-B, and iMLS-C. The iMLS-A strains (n = 84) were highly resistant to the 14-, 15-, and 16-membered macrolides and demonstrated reduced susceptibility to low-level resistance to HMR3004. The iMLS-B strains (n = 12) were highly resistant to the 14- and 15-membered macrolides, susceptible to the 16-membered macrolides (but highly resistant to josamycin after induction), and susceptible to HMR3004 (but intermediate or resistant after induction). The iMLS-C strains (n = 24) had lower levels of resistance to the 14- and 15-membered macrolides (with erythromycin MICs increasing two to four times after

  14. New macrolides active against Streptococcus pyogenes with inducible or constitutive type of macrolide-lincosamide-streptogramin B resistance.

    PubMed

    Fernandes, P B; Baker, W R; Freiberg, L A; Hardy, D J; McDonald, E J

    1989-01-01

    Macrolide-resistant bacteria can be classified as inducibly resistant or constitutively resistant. Inducibly resistant bacteria are resistant to 14-membered macrolides, such as erythromycin and clarithromycin (A-56268), but are susceptible to the 16-membered macrolides, such as tylosin and spiramycin, as well as to clindamycin. Constitutively resistant bacteria are resistant to macrolide-lincosamide-streptogramin B antibiotics. In this study, the MICs of several erythromycin and clarithromycin analogs against macrolide-susceptible and macrolide-resistant Streptococcus pyogenes strains were determined. Four 11,12-carbamate analogs of clarithromycin had lower MICs than erythromycin did against S. pyogenes with the inducible or constitutive type of macrolide-lincosamide-streptogramin B resistance. Five 11,12-carbonate analogs of erythromycin with modifications at the 4" position of cladinose had lower MICs than did erythromycin against S. pyogenes with the constitutive type of resistance, and one of these compounds, which had a naphthyl-glycyl substitution at the 4" position, had a lower MIC than erythromycin against both the inducibly resistant and constitutively resistant strains. Two analogs of erythromycin with a modification on the 4" position of cladinose had lower MICs than erythromycin did against the constitutively resistant organisms but not against the inducibly resistant organisms. Thus, 14-membered macrolides can be modified so as to confer a low MIC when tested in vitro.

  15. Analysis of multiply antimicrobial-resistant isolates of Streptococcus pneumoniae from the United States.

    PubMed Central

    McDougal, L K; Facklam, R; Reeves, M; Hunter, S; Swenson, J M; Hill, B C; Tenover, F C

    1992-01-01

    Streptococcus pneumoniae isolates resistant to penicillin, chloramphenicol, tetracycline and sulfamethoxazole-trimethroprim are being recovered with increasing frequency in the United States. We analyzed the penicillin-binding proteins (PBPs), multilocus enzyme electrophoresis (MLEE) genotypes, and ribotypes of 22 multiresistant serotype 23F isolates of S. pneumoniae from the United States and 1 isolate each from Spain and South Africa. Also included were seven multiresistant isolates of other serotypes, three penicillin-resistant but chloramphenicol-susceptible serotype 23F isolates, and two penicillin-susceptible isolates (one penicillin-susceptible isolate was serotype 23F). Fifteen of the 22 multiresistant isolates from the United States and the isolates from Spain and South Africa had identical PBP patterns, MLEE profiles, and ribotypes. Six of the remaining seven multiresistant isolates were related by PBP pattern, but demonstrated slightly different MLEE and/or ribotype profiles, possibly because of acquisition of additional resistance markers (four of the six isolates were also resistant to erythromycin). The remaining multiresistant serotype 23F isolate had a unique PBP pattern and ribotype and was only distantly related to the other pneumococcal isolates by MLEE analysis. The PBP patterns, MLEE profiles, and ribotypes of the multiresistant serotype 23F isolates were easily distinguished from those of six multiresistant isolates of other serotypes; three other penicillin-resistant, chloramphenicol-susceptible, serotype 23F isolates; and two penicillin-susceptible isolates. One exception was a multiresistant serotype 19A isolate that was highly related to the clonal group by PBP pattern and MLEE analysis and that had a ribotype similar to those of the other erythromycin-resistant serotype 23F isolates. MLEE analysis and ribotyping were more discriminating than were the PBP patterns in discerning strain differences. These data strongly suggest that a

  16. Interspecies recombination in type II topoisomerase genes is not a major cause of fluoroquinolone resistance in invasive Streptococcus pneumoniae isolates in the United States.

    PubMed

    Pletz, Mathias W R; McGee, Lesley; Beall, Bernard; Whitney, Cynthia G; Klugman, Keith P

    2005-02-01

    Mutations in the topoisomerase type II enzymes account for fluoroquinolone resistance in Streptococcus pneumoniae. These mutations can arise spontaneously or be transferred by intraspecies or interspecies recombination, primarily with viridans streptococci. We analyzed the nucleotide sequences of the quinolone resistance-determining regions of 49 invasive levofloxacin-resistant pneumococcal isolates and did not find any evidence for interspecies recombination.

  17. Are Sewage Treatment Plants Promoting Antibiotic Resistance?

    EPA Science Inventory

    1. Introduction 1.1. How bacteria exhibit resistance 1.1.1. Resistance to -lactams 1.1.2. Resistance to sulphonamides and trimethoprim 1.1.3. Resistance to macrolides 1.1.4. Resistance to fluoroquinolones 1.1.5. Resistance to tetracyclines 1.1.6. Resistance to nitroimidaz...

  18. Are Sewage Treatment Plants Promoting Antibiotic Resistance?

    EPA Science Inventory

    1. Introduction 1.1. How bacteria exhibit resistance 1.1.1. Resistance to -lactams 1.1.2. Resistance to sulphonamides and trimethoprim 1.1.3. Resistance to macrolides 1.1.4. Resistance to fluoroquinolones 1.1.5. Resistance to tetracyclines 1.1.6. Resistance to nitroimidaz...

  19. [The genetic features of drug resistance to group A streptococcus and macrolides antibiotics among pediatric patients in Beijing 2012].

    PubMed

    Peng, Xiao-min; Yang, Peng; Liu, Shuang; Li, Jing; Zhang, Dai-tao; Liu, Yi-meng; Liang, Hui-jie; Cui, Shu-juan; Wu, Shuang-sheng; Wang, Quan-yi

    2013-11-01

    To investigate the genetic features of drug resistance to group A streptococcus(GAS) and macrolides antibiotics among pediatric patients in Beijing 2012. A total of 199 strains of GAS were collected from 36 hospitals in Beijing between May and July, 2012. All strains were isolated from oropharyngeal swabs. The minimum inhibitory concentrations (MICs) of ten antibiotics (penicillin, ampicillin, erythromycin, clindamycin, tetracycline, levofloxacin, tigecycline, vancomycin, linezolid and streptogramin) were detected by VITEK-2 compact with GPS-67 test kit. The genes encoding macrolides resistance (ermA, ermB and mefA ) were amplified and tested by PCR. The macrolides resistant phenotype of group A streptococcus was detected by double disc test (D-test). Among 199 strains of GAS collected in this study, 101(50.8%) were from suburbs and the other 98(49.2%) were from urban areas. 111(55.8%) strains were collected from scarlet fever patients while the other 88(44.2%) were from oropharyngeal infection cases. All the strains were sensitive to penicillin and ampicillin, and the percentage of resistance to erythromycin, clindamycin and tetracycline were 96.5% (192/199), 95.5% (190/199) and 92.0% (183/199), respectively. All strains were susceptible to levofloxacin, tigecycline, vancomycin, linezolid and streptogramin. The rates of resistance to erythromycin, clindamycin and tetracycline were different in different districts, however, the difference in it between ages and clinical diagnosis did not show statistical significance (P > 0.05) . The detected rate of drug resistance gene ermB was 98.5% (196/199). The gene ermA was only detected out in 5 strains and the gene mefA was not detected out. 199 strains showed A macrolides resistant phenotype cMLS, while the phenotype iMLS was not found in this study. This study demonstrates the high level of clindamycin resistance in group A streptococcus collected from children in Beijing, 2012. The macrolides resistance of group A

  20. [Evaluation of penicillin-binding protein genotypes in penicillin susceptible and resistant Streptococcus pneumoniae isolates].

    PubMed

    Aslan, Gönül; Tezcan, Seda; Delialioğlu, Nuran; Aydın, Fatma Esin; Kuyucu, Necdet; Emekdaş, Gürol

    2012-04-01

    Penicillin-binding proteins (PBPs) are the natural targets of beta-lactam antibiotics and mutations in pbp1a, pbp2b, and pbp2x genes, which encode PBPs, are responsible for resistance to beta-lactams in Streptococcus pneumoniae. In the present study, we intended to determine how often the common mutation patterns occurred within the pbp1a, pbp2b, and pbp2x PBP gene regions and evaluate the PBP genotype mutations which were associated with penicillin resistance in several penicillin-susceptible and - resistant S.pneumoniae isolates in Mersin, Turkey. A total of 62 S.pneumoniae strains isolated from different clinical specimens (32 nasopharyngeal swab, 16 sputum, 3 blood, 3 wound, 2 cerebrospinal fluids and one of each urine, abscess, bronchoalveolar lavage, conjunctival swab, tracheal aspirate, middle ear effusion) were included in the study. Penicillin susceptibilities of the isolates were searched by disc diffusion and E-test methods, and 23 of them were identified as susceptible, 31 were intermediate susceptible, and eight were resistant to penicillin. A rapid DNA extraction procedure was performed for the isolation of nucleic acids from the strains. Distribution of PBP gene mutations in pbp1a, pbp2b, and pbp2x gene regions related to penicillin resistance was determined by using a wild-type specific polymerase chain reaction (PCR) based technique. PBP gene alterations of those isolates were also evaluated in relation to penicillin susceptibility and resistance patterns. Twenty two (95.7%) of 23 penicillin-susceptible S.pneumoniae isolates exhibited no mutation in the three PBP genes (pbp1a, pbp2x, and pbp 2b), while 1 (4.3%) of these harbored mutations in all of the three PBP genes. The penicillin-intermediate susceptible S.pneumoniae isolates exhibited various combinations of mutations. One (3.2%) of 31 penicillin-intermediate susceptible isolates exhibited no mutation in the three PBP genes, while 22 (71%) of them yielded mutations in all of the three PBP

  1. Streptococcus pneumoniae R6 interspecies transformation: genetic analysis of penicillin resistance determinants and genome-wide recombination events.

    PubMed

    Sauerbier, Julia; Maurer, Patrick; Rieger, Martin; Hakenbeck, Regine

    2012-11-01

    Interspecies gene transfer has been implicated as the major driving force for the evolution of penicillin resistance in Streptococcus pneumoniae. Genomic alterations of S. pneumoniae R6 introduced during four successive transformations with DNA of the high-level penicillin-resistant Streptococcus mitis B6 with beta-lactam selection have now been determined and the contribution of genes to high resistance levels was analysed genetically. Essential for high level resistance to penicillins of the transformant CCCB was the combination of murM(B) (6) and the 3' region of pbp2b(B) (6) . Sequences of both genes were detected in clinical isolates of S. pneumoniae, confirming the participation of S. mitis in the global gene pool of beta-lactam resistance determinants. The S. mitis PBP1b gene which contains an authentic stop codon within the transpeptidase domain is now shown to contribute only marginal to resistance, but it is possible that the presence of its transglycosylase domain is important in the context of cognate PBPs. The genome sequence of CCCB revealed 36 recombination events, including deletion and acquisition of genes and repeat elements. A total of 78 genes were affected representing 67 kb or 3.3% of the genome, documenting extensive alterations scattered throughout the genome.

  2. Capsule Switching and Antimicrobial Resistance Acquired during Repeated Streptococcus pneumoniae Pneumonia Episodes.

    PubMed

    Chang, Bin; Nariai, Akiyoshi; Sekizuka, Tsuyoshi; Akeda, Yukihiro; Kuroda, Makoto; Oishi, Kazunori; Ohnishi, Makoto

    2015-10-01

    Streptococcus pneumoniae colonizes the nasopharyngeal mucus in healthy people and causes otitis media, pneumonia, bacteremia, and meningitis. In this study, we analyzed an S. pneumoniae strain that caused 7 repeated pneumonia episodes in an 80-month-old patient with cerebral palsy during a period of 25 months. A total of 10 S. pneumoniae strains were obtained from sputum samples, and serotype 6B was isolated from samples from the first 5 episodes, whereas serotype 6A was isolated from samples from the last 2. Whole-genome sequencing showed clonality of the 10 isolates with 10 single nucleotide polymorphisms (SNPs) in the genomes. Among these SNPs, one single point mutation in the wciP gene was presumed to relate to the serotype switching from 6B to 6A, and the other mutations in parC and gyrA were related to fluoroquinolone resistance. These results suggested that an S. pneumoniae strain, which asymptomatically colonized the patient's nasopharynx or was horizontally transmitted from an asymptomatic carrier, caused the repeated pneumonia events. Phenotypic variations in the capsule type and antimicrobial susceptibility occurred during the carrier state. Hyporesponsiveness to serotypes 6B and 6A of S. pneumoniae was found even after vaccination with the 7-valent pneumococcal conjugate vaccine and the 23-valent pneumococcal polysaccharide vaccine. After an additional vaccination with the 13-valent pneumococcal conjugate vaccine, opsonic activities for both serotypes 6A and 6B significantly increased and are expected to prevent relapse by the same strain.

  3. Optimization of culture conditions to obtain maximal growth of penicillin-resistant Streptococcus pneumoniae

    PubMed Central

    Restrepo, Andrea V; Salazar, Beatriz E; Agudelo, María; Rodriguez, Carlos A; Zuluaga, Andres F; Vesga, Omar

    2005-01-01

    Background Streptococcus pneumoniae, particularly penicillin-resistant strains (PRSP), constitute one of the most important causes of serious infections worldwide. It is a fastidious microorganism with exquisite nutritional and environmental requirements to grow, a characteristic that prevents the development of useful animal models to study the biology of the microorganism. This study was designed to determine optimal conditions for culture and growth of PRSP. Results We developed a simple and reproducible method for culture of diverse strains of PRSP representing several invasive serotypes of clinical and epidemiological importance in Colombia. Application of this 3-step culture protocol consistently produced more than 9 log10 CFU/ml of viable cells in the middle part of the logarithmic phase of their growth curve. Conclusion A controlled inoculum size grown in 3 successive steps in supplemented agar and broth under 5% CO2 atmosphere, with pH adjustment and specific incubation times, allowed production of great numbers of PRSP without untimely activation of autolysis mechanisms. PMID:15932633

  4. Capsule Switching and Antimicrobial Resistance Acquired during Repeated Streptococcus pneumoniae Pneumonia Episodes

    PubMed Central

    Nariai, Akiyoshi; Sekizuka, Tsuyoshi; Akeda, Yukihiro; Kuroda, Makoto; Oishi, Kazunori; Ohnishi, Makoto

    2015-01-01

    Streptococcus pneumoniae colonizes the nasopharyngeal mucus in healthy people and causes otitis media, pneumonia, bacteremia, and meningitis. In this study, we analyzed an S. pneumoniae strain that caused 7 repeated pneumonia episodes in an 80-month-old patient with cerebral palsy during a period of 25 months. A total of 10 S. pneumoniae strains were obtained from sputum samples, and serotype 6B was isolated from samples from the first 5 episodes, whereas serotype 6A was isolated from samples from the last 2. Whole-genome sequencing showed clonality of the 10 isolates with 10 single nucleotide polymorphisms (SNPs) in the genomes. Among these SNPs, one single point mutation in the wciP gene was presumed to relate to the serotype switching from 6B to 6A, and the other mutations in parC and gyrA were related to fluoroquinolone resistance. These results suggested that an S. pneumoniae strain, which asymptomatically colonized the patient's nasopharynx or was horizontally transmitted from an asymptomatic carrier, caused the repeated pneumonia events. Phenotypic variations in the capsule type and antimicrobial susceptibility occurred during the carrier state. Hyporesponsiveness to serotypes 6B and 6A of S. pneumoniae was found even after vaccination with the 7-valent pneumococcal conjugate vaccine and the 23-valent pneumococcal polysaccharide vaccine. After an additional vaccination with the 13-valent pneumococcal conjugate vaccine, opsonic activities for both serotypes 6A and 6B significantly increased and are expected to prevent relapse by the same strain. PMID:26269621

  5. Population Structure and Antimicrobial Resistance Profiles of Streptococcus suis Serotype 2 Sequence Type 25 Strains

    PubMed Central

    Athey, Taryn B. T.; Teatero, Sarah; Takamatsu, Daisuke; Wasserscheid, Jessica; Dewar, Ken; Gottschalk, Marcelo; Fittipaldi, Nahuel

    2016-01-01

    Strains of serotype 2 Streptococcus suis are responsible for swine and human infections. Different serotype 2 genetic backgrounds have been defined using multilocus sequence typing (MLST). However, little is known about the genetic diversity within each MLST sequence type (ST). Here, we used whole-genome sequencing to test the hypothesis that S. suis serotype 2 strains of the ST25 lineage are genetically heterogeneous. We evaluated 51 serotype 2 ST25 S. suis strains isolated from diseased pigs and humans in Canada, the United States of America, and Thailand. Whole-genome sequencing revealed numerous large-scale rearrangements in the ST25 genome, compared to the genomes of ST1 and ST28 S. suis strains, which result, among other changes, in disruption of a pilus island locus. We report that recombination and lateral gene transfer contribute to ST25 genetic diversity. Phylogenetic analysis identified two main and distinct Thai and North American clades grouping most strains investigated. These clades also possessed distinct patterns of antimicrobial resistance genes, which correlated with acquisition of different integrative and conjugative elements (ICEs). Some of these ICEs were found to be integrated at a recombination hot spot, previously identified as the site of integration of the 89K pathogenicity island in serotype 2 ST7 S. suis strains. Our results highlight the limitations of MLST for phylogenetic analysis of S. suis, and the importance of lateral gene transfer and recombination as drivers of diversity in this swine pathogen and zoonotic agent. PMID:26954687

  6. [Bactericidal activity of sitafloxacin and other new quinolones against antimicrobial resistant Streptococcus pneumoniae].

    PubMed

    Kobayashi, Intetsu; Kanayama, Akiko; Hasegawa, Miyuki; Kaneko, Akihiro

    2013-02-01

    We conducted a study assess the bactericidal activity of sitafloxacin (STFX) against Streptococcus pneumoniae isolates recovered from respiratory infections including penicillin-resistant (PRSP) isolates, macrolide resistant isolates possessing mefA and ermB resistance genes and quinolone resistance isolates with mutations in gyrA or gyrA and parC. Each isolate tested was grown in hemosupplemented Mueller-Hinton broth and adjusted to approximately 10(5) CFU/ mL. Isolates were than exposed to a Cmax antimicrobial blood level that would be attained with routine antimicrobial administration and an antimicrobial level that would be expected 4 hours post-Cmax (Cmax 4hr). Bactericidal activity was measured for up to 8 hours. Excluding a subset of S. pneumoniae isolates with mutations in the quinolone resistance determining region (QRDR), all quinolones showed bactericidal activity at Cmax and Cmax 4 hr antimicrobial concentrations for up to 8 hours. Against S. pneumoniae isolates with either gyrA or gyrA and parC mutations, bactericidal activity of STFX was shown for up to 4 to 8 hours following Cmax based on a limit of detection of < 1.3 log CFU/mL. Garenoxacin (GRNX) did not showed bactericidal activity below the limit of detection for up to 8 hours with exposure to Cmax and no bactericidal activity was seen with levofloxacin. When all quinolones tested where adjusted to concentrations corresponding to their MICs, STFX showed the most rapid bactericidal activity against PRSP. This rapid bactericidal activity in PRSP is a key to the effectiveness of STFX. Our findings show that beyond inhibition of bacterial replication by blocking their DNA replication pathway and synthesis of proteins, STFX demonstrated characteristics contributing to greater bactericidal activity compared to GRNX. In conclusion, of the newer quinolones, STFX showed the strongest bactericidal activity against S. pneumoniae isolates with mutations in the QRDR which indicates that it may show the most

  7. Antibiotic resistance and serotypes of 100 Streptococcus pneumoniae strains isolated in a children's hospital in Barcelona, Spain.

    PubMed Central

    Latorre, C; Juncosa, T; Sanfeliu, I

    1985-01-01

    A total of 100 Streptococcus pneumoniae strains with various penicillin G susceptibilities, isolated in Barcelona, Spain, from different pediatric sources during 1983 and the first 4 months of 1984, were tested for susceptibility to tetracycline, chloramphenicol, erythromycin, clindamycin, vancomycin, and rifampin. The isolates were distributed in nine patterns of antibiotic resistance, and 15 different serotypes were encountered. The high incidence of resistance to multiple antibiotics clearly indicates the need to perform antibiotic susceptibility testing of all pneumococcal isolates with proved pathologic significance to avoid therapeutic failure. PMID:3834840

  8. Canadian national survey of prevalence of antimicrobial resistance among clinical isolates of Streptococcus pneumoniae. Canadian Bacterial Surveillance Network.

    PubMed Central

    Simor, A E; Louie, M; Low, D E

    1996-01-01

    The antimicrobial susceptibilities of 1,089 clinical isolates of Streptococcus pneumoniae obtained from 39 laboratories across Canada between October 1994 and August 1995 were determined. A total of 91 isolates (8.4%) demonstrated intermediate resistance (MIC, 0.1 to 1.0 microgram/ml) and 36 (3.3%) had high-level resistance (MIC, > or = 2.0 micrograms/ml) to penicillin. Penicillin-resistant strains were more likely to have been recovered from normally sterile sites (P = 0.005) and to be cross-resistant to several beta-lactam and non-beta-lactam antimicrobial agents (P < 0.05). These results indicate that there has been a recent significant increase in the prevalence of antibiotic-resistant S. pneumoniae in Canada. PMID:8878605

  9. Clindamycin resistant emm33 Streptococcus pyogenes emerged among invasive infections in Helsinki metropolitan area, Finland, 2012 to 2013.

    PubMed

    Pesola, A K; Sihvonen, R; Lindholm, L; Pätäri-Sampo, A

    2015-05-07

    In 2012, blood, skin and soft tissue infections caused by clindamycin resistant Streptococcus pyogenes (group A streptococcus; GAS) appeared to be increasing in the Helsinki metropolitan area. We compared monthly percentages of clindamycin resistant isolates in the area between 2012 and 2013, with those in 2010 and 2011. Resistance frequency in terms of patient age was also studied. We reviewed the medical records of bacteraemic cases in 2012 and 2013 and linked the data to emm types. To inform on the emm distribution among GAS isolated from skin and soft tissue infections during the epidemic, GAS isolates of one month (March 2013) were emm typed. For GAS blood, skin, and soft tissue isolates taken together, the proportions of clindamycin resistant isolates were significantly higher in 2012 and 2013 (23% and 17%, respectively) compared with the two previous years (3%, p<0,001). The erythromycin resistance percentages were almost equal to clindamycin (22% and 17%) in 2012 and 2013, respectively. Clindamycin resistance was most frequent in GAS isolates of 40 to 60 year-old patients (148/417; 36%). Among clindamycin resistant isolates, 12 of 14 blood isolates from 2012 to 2013, and 11 of 13 skin and soft tissue isolates from March 2013, were emm33. Emm33 GAS bacteraemia was associated with clindamycin and erythromycin resistance (odds ratio (OR): 7.0; 95% confidence interval (CI): 1.9-25.3). Infection focus was mainly the skin; either cellulitis (7/12) or necrotising fasciitis (3/12). All emm33 GAS isolates harboured the ermTR resistance gene with constitutive macrolides, lincosamides and streptogramines B (MLS(B)) phenotype. Emm33 GAS was responsible for the higher proportion of clindamycin resistance in skin, soft tissue, and blood isolates locally in 2012 and 2013.

  10. Determination of Characteristics of Erythromycin Resistant Streptococcus pneumoniae with Preferred PCV Usage in Iran.

    PubMed

    Talebi, Malihe; Azadegan, Azadeh; Sadeghi, Javad; Ahmadi, Ali; Ghanei, Mostafa; Katouli, Mohammad; Owlia, Parviz; Pourshafie, Mohammad R

    2016-01-01

    Amongst 100 Streptococcus pneumoniae isolated from clinical cases and nasopharynx of healthy individuals, 60 erythromycin resistant strains were isolated and characterized using MLST, PFGE, transposon analysis and Quellung reaction. Most of the S. pneumoniae erythromycin resistant (80%) were found to be attributable to the ermB-edncoded ribosome methylase activity which differs from the dominant mechanism of macrolide resistance seen in North America. The most predominant transposons were; Tn1545/6003 (27%), Tn6002 (22%), Tn2009 (20%), Tn2010 (17%). Number of the clinical isolates carrying Tn2010 was more significant than the normal flora. The serotypes found were; 14 (33%), 3 (22%), 23F (15%), 19F (15%), 19A (7%), 6A (3%), 9V (3%) and 6B (2%). The most prevalent serotypes among the clinical (n = 28) and normal flora (n = 32) isolates were serotypes 14 (46%) and 3 (31%), respectively. The most prevalent vaccine serotypes amongst the clinical isolates and the healthy individuals were pneumococcal conjugate vaccines (PCV) 13 and PCV10, respectively. PFGE revealed 34 pulsotypes with 9 common and 25 single types. Significant number of the normal isolates belonged to CT5 and CT6. On the other hand, significant number of clinical isolates belonged to CT8 as compared to the normal flora isolates. MLST showed 2 dominant sequence types. ST3130 (23%) and ST180 (22%) were the most predominant sequence types in the clinical and normal isolates, respectively. There was no significant difference in other sequence types between clinical and normal flora isolates. Three polyclonal complexes including Sweden15A -25, Spain23F-1 and Spain9V-3 constituted 58% of the isolates. Our results suggest that the genetic diversity and transposon distribution were high among S. pneumoniae, particularly in the isolates containing erm(B) and double antibiotic resistant genes (erm/mef). The results presented here could influence the change in the current vaccination practices in Iran which

  11. Determination of Characteristics of Erythromycin Resistant Streptococcus pneumoniae with Preferred PCV Usage in Iran

    PubMed Central

    Talebi, Malihe; Azadegan, Azadeh; Sadeghi, Javad; Ahmadi, Ali; Katouli, Mohammad

    2016-01-01

    Amongst 100 Streptococcus pneumoniae isolated from clinical cases and nasopharynx of healthy individuals, 60 erythromycin resistant strains were isolated and characterized using MLST, PFGE, transposon analysis and Quellung reaction. Most of the S. pneumoniae erythromycin resistant (80%) were found to be attributable to the ermB-edncoded ribosome methylase activity which differs from the dominant mechanism of macrolide resistance seen in North America. The most predominant transposons were; Tn1545/6003 (27%), Tn6002 (22%), Tn2009 (20%), Tn2010 (17%). Number of the clinical isolates carrying Tn2010 was more significant than the normal flora. The serotypes found were; 14 (33%), 3 (22%), 23F (15%), 19F (15%), 19A (7%), 6A (3%), 9V (3%) and 6B (2%). The most prevalent serotypes among the clinical (n = 28) and normal flora (n = 32) isolates were serotypes 14 (46%) and 3 (31%), respectively. The most prevalent vaccine serotypes amongst the clinical isolates and the healthy individuals were pneumococcal conjugate vaccines (PCV) 13 and PCV10, respectively. PFGE revealed 34 pulsotypes with 9 common and 25 single types. Significant number of the normal isolates belonged to CT5 and CT6. On the other hand, significant number of clinical isolates belonged to CT8 as compared to the normal flora isolates. MLST showed 2 dominant sequence types. ST3130 (23%) and ST180 (22%) were the most predominant sequence types in the clinical and normal isolates, respectively. There was no significant difference in other sequence types between clinical and normal flora isolates. Three polyclonal complexes including Sweden15A -25, Spain23F-1 and Spain9V-3 constituted 58% of the isolates. Our results suggest that the genetic diversity and transposon distribution were high among S. pneumoniae, particularly in the isolates containing erm(B) and double antibiotic resistant genes (erm/mef). The results presented here could influence the change in the current vaccination practices in Iran which

  12. Treatment of experimental pneumonia due to penicillin-resistant Streptococcus pneumoniae in immunocompetent rats.

    PubMed Central

    Gavaldà, J; Capdevila, J A; Almirante, B; Otero, J; Ruiz, I; Laguarda, M; Allende, H; Crespo, E; Pigrau, C; Pahissa, A

    1997-01-01

    A model of pneumonia due to Streptococcus pneumoniae resistant to penicillin was developed in immunocompetent Wistar rats and was used to evaluate the efficacies of different doses of penicillin, cefotaxime, cefpirome, and vancomycin. Adult Wistar rats were challenged by intratracheal inoculation with 3 x 10(9) CFU of one strain of S. pneumoniae resistant to penicillin (MICs of penicillin, cefotaxime, cefpirome, and vancomycin, 2, 1, 0.5, and 0.5 microg/ml, respectively) suspended in brain heart broth supplemented with 0.7% agar. The rats experienced a fatal pneumonia, dying within 5 days and with peak mortality (70 to 80%) occurring 48 to 72 h after infection, and the bacterial counts in the lungs persisted from 8.87 +/- 0.3 log10 CFU/g of lung at 24 h of the infection to 9.1 +/- 0.3 log10 CFU/g at 72 h. Four hours after infection the animals were randomized into the following treatment groups: (i) control without treatment, (ii) penicillin G at 100,000 IU/kg of body weight every 2 h, (iii) penicillin G at 250,000 IU/kg every 2 h, (iv) cefotaxime at 100 mg/kg every 2 h, (v) cefpirome at 200 mg/kg every 2 h, and (vi) vancomycin at 50 mg/kg every 8 h. Two different protocols were used for the therapeutic efficacy studies: four doses of beta-lactams and one dose of vancomycin or eight doses of beta-lactams and two doses of vancomycin. Results of the therapy for experimental pneumonia caused by penicillin-resistant S. pneumoniae showed that initially, all the antimicrobial agents tested had similar efficacies, but when we prolonged the treatment, higher doses of penicillin, cefotaxime, and cefpirome were more effective than penicillin at lower doses in decreasing the residual bacterial titers in the lungs. Also, when we extended the treatment, vancomycin was more efficacious than penicillin at lower doses but was less efficacious than higher doses of penicillin or cefpirome. The model that we have developed is simple and amenable for inducing pneumonia in

  13. High-level fluoroquinolone resistance in Streptococcus pneumoniae requires mutations in parC and gyrA.

    PubMed Central

    Janoir, C; Zeller, V; Kitzis, M D; Moreau, N J; Gutmann, L

    1996-01-01

    The mechanism of high-level fluoroquinolone resistance was studied in strains of Streptococcus pneumoniae, either selected in vitro or isolated from clinical samples. By using DNA from these high-level-resistant strains, low-level-resistant transformants (MIC of pefloxacin, > or = 32 micrograms/ml; MIC of ciprofloxacin, 4 micrograms/ml; MIC of sparfloxacin, 0.50 micrograms/ml) were obtained at high frequencies (ca.10(-2)), while high-level-resistant transformants (MIC of pefloxacin, > or = 64 micrograms/ml; MIC of ciprofloxacin, 16 to 64 micrograms/ml; MIC of sparfloxacin, > or = 8 micrograms/ml) were obtained only at low frequencies (ca.10(-4)). This suggested that mutations in at least two unlinked genes were necessary to obtain high-level resistance. Low-level resistance was associated with ParC mutations (change from Ser to Tyr at position 79 [Ser79Tyr], Ser79Phe, or Asp83Gly). ParC mutations were associated, in high-level-resistant strains and transformants, with alterations in the quinolone resistance-determining region of GyrA (Ser84Tyr, Ser84Phe, and/or Glu88Lys). Low-level resistance was shown to be necessary for expression of the gyrA mutations. No mutation in the region corresponding to the quinolone resistance-determining region of GyrB and no alteration of drug accumulation were found. PMID:9124836

  14. Induction of Efflux-Mediated Macrolide Resistance in Streptococcus pneumoniae ▿

    PubMed Central

    Chancey, Scott T.; Zhou, Xiaoliu; Zähner, Dorothea; Stephens, David S.

    2011-01-01

    The antimicrobial efflux system encoded by the operon mef(E)-mel on the mobile genetic element MEGA in Streptococcus pneumoniae and other Gram-positive bacteria is inducible by macrolide antibiotics and antimicrobial peptides. Induction may affect the clinical response to the use of macrolides. We developed mef(E) reporter constructs and a disk diffusion induction and resistance assay to determine the kinetics and basis of mef(E)-mel induction. Induction occurred rapidly, with a >15-fold increase in transcription within 1 h of exposure to subinhibitory concentrations of erythromycin. A spectrum of environmental conditions, including competence and nonmacrolide antibiotics with distinct cellular targets, did not induce mef(E). Using 16 different structurally defined macrolides, induction was correlated with the amino sugar attached to C-5 of the macrolide lactone ring, not with the size (e.g., 14-, 15- or 16-member) of the ring or with the presence of the neutral sugar cladinose at C-3. Macrolides with a monosaccharide attached to C-5, known to block exit of the nascent peptide from the ribosome after the incorporation of up to eight amino acids, induced mef(E) expression. Macrolides with a C-5 disaccharide, which extends the macrolide into the ribosomal exit tunnel, disrupting peptidyl transferase activity, did not induce it. The induction of mef(E) did not require macrolide efflux, but the affinity of macrolides for the ribosome determined the availability for efflux and pneumococcal susceptibility. The induction of mef(E)-mel expression by inducing macrolides appears to be based on specific interactions of the macrolide C-5 saccharide with the ribosome that alleviate transcriptional attenuation of mef(E)-mel. PMID:21537010

  15. Emergence of Neoteric Serotypes Among Multidrug Resistant Strains of Streptococcus pneumoniae Prevalent in Egypt

    PubMed Central

    Bahy, Rehab H; Hamouda, Hayam M; Shahat, Amal S; Yassin, Aymen S; Amin, Magdy A

    2016-01-01

    Background Streptococcus pneumoniae is still one of the major causes of morbidity and mortality worldwide. The prevalent serotype distribution had shown variation along different studies conducted at different time intervals. In order to efficiently assess the epidemiology of the diseases for effective preventive and treatment strategies, serotype prevalence need to be periodically reassessed. Objectives Conducting a reassessment of the prevalent S. pneumoniae serotypes in Egypt as an essential step in the search for a regional vaccine. In addition, monitoring the antibiotic susceptibility patterns of pneumococcal strains currently causing infections as an evaluation of therapeutic strategies applied. Materials and Methods A total of 100 specimens of different sources were collected in Cairo, Egypt, from 2011 to 2013, representing almost all different types of diseases caused by S. pneumoniae such as meningitis, pneumonia, otitis media and sinusitis. Conventional and molecular identification methods were performed, the antimicrobial susceptibility patterns were assessed and serotyping was done using PCR assays to identify the most prevalent types. In addition, detection of certain virulence genes for the most prevalent serotypes was carried out. Results Our results revealed that in Egypt, currently, the most prevalent serotypes were serogroup 6 and serotype 19F as they represented 58% of all isolates. High rates of resistance were found to different antibiotic classes. The lytA and psaA genes were found to be more sensitive for S. pneumoniae identification than ply. Conclusions Our study illustrates the importance of constantly monitoring the prevalent serotypes in any region in order to aid in the development of more effective vaccines. PMID:27303614

  16. Cloning and characterization of the tetracycline resistance determinant of and several promoters from within the conjugative transposon Tn919.

    PubMed Central

    Hill, C; Venema, G; Daly, C; Fitzgerald, G F

    1988-01-01

    Tn919 is a 15- to 16-kilobase (kb) tetracycline resistance conjugative transposon that was originally isolated from Streptococcus sanguis FC1. The tetracycline resistance determinant (tet) was found on a 4.2-kb HindII fragment by in vitro deletion analysis. This fragment was subcloned to a pWV01 origin capable of directing replication in Escherichia coli, Bacillus subtilis, and Streptococcus lactis, and expression was observed in all three genera. In all cases, expression was weaker when only the 4.2-kb cloned fragment rather than the full transposon was present. The resistance gene is of the streptococcal tetM class and codes for a protein of approximately 70 kilodaltons. The restriction map resembles that of the tetM gene of Tn1545 (P. Martin, P. Trieu-Cuot, and P. Courvalin, Nucleic Acids Res. 14:7047-7058, 1986), which codes for a protein of 72.5 kilodaltons. A number of transposon-derived promoter-bearing fragments were also cloned and sequenced. These closely resemble the consensus sequence of E. coli and B. subtilis promoters. Fusion experiments with a truncated lacZ gene indicate the possibility of an open reading frame for one of the promoters. Images PMID:2839111

  17. The change of macrolide resistance rates in group A Streptococcus isolates from children between 2002 and 2013 in Asahikawa city.

    PubMed

    Sakata, Hiroshi

    2015-05-01

    This study targeted patients in the Department of Pediatrics, Asahikawa Kosei Hospital, between January 2002 and December 2013. In patients suspected of having hemolytic streptococcal infection, Group A Streptococcus (GAS) strains isolated from a throat swab were examined for antimicrobial susceptibility testing. The MICs were measured by the broth microdilution method. The annual number of GAS strains examined for antimicrobial susceptibility testing ranged from 28 to 65 strains, for a total of 574 strains. Some of the isolates obtained from 2006 to 2009 and from 2011 to 2013 were analyzed to determine their emm types. An erythromycin (EM) resistant strain was not detected until 2004, but one EM-resistant strain appeared in 2005. Subsequently, EM-resistant strains rapidly increased, and 48 of 65 strains (73.8%) examined in 2009 were resistant. In 2010, the number of EM-resistant strains decreased to 12 of 36 strains (33.3%). However, it gradually increased afterwards, and 37 of 60 strains (61.7%) were resistant in 2013. Out of 574 strains examined, 184 exhibited EM-resistance, and the overall resistance rate was 31.9%. Partitioning the 124 strains examined between 2006 and 2008 according to emm types, only emm28 strains, which exhibited a high resistance rate, and emm12 strains demonstrated resistance. For the 142 strains examined between 2011 and 2013, the resistance rate of emm28 strains was similarly high; the resistance of emm12 strains significantly increased, and emm1 strains exhibited a high resistance rate. The number of emm types associated with the resistant strains increased. Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  18. Ser-127-to-Leu substitution in the DNA gyrase B subunit of Streptococcus pneumoniae is implicated in novobiocin resistance.

    PubMed

    Muñoz, R; Bustamante, M; de la Campa, A G

    1995-07-01

    We report the cloning of the gyrB gene from Streptococcus pneumoniae 533 that carries the nov-1 allele. The gyrB gene codes for a protein homologous to the gyrase B subunit of archaebacteria and eubacteria. The same amino acid substitution (Ser-127 to Leu) confers novobiocin resistance on four isolates of S. pneumoniae. This amino acid position is equivalent to Val-120 of Escherichia coli GyrB, a residue that lies inside the ATP-binding domain as revealed by the crystal structure of the protein.

  19. Ser-127-to-Leu substitution in the DNA gyrase B subunit of Streptococcus pneumoniae is implicated in novobiocin resistance.

    PubMed Central

    Muñoz, R; Bustamante, M; de la Campa, A G

    1995-01-01

    We report the cloning of the gyrB gene from Streptococcus pneumoniae 533 that carries the nov-1 allele. The gyrB gene codes for a protein homologous to the gyrase B subunit of archaebacteria and eubacteria. The same amino acid substitution (Ser-127 to Leu) confers novobiocin resistance on four isolates of S. pneumoniae. This amino acid position is equivalent to Val-120 of Escherichia coli GyrB, a residue that lies inside the ATP-binding domain as revealed by the crystal structure of the protein. PMID:7608096

  20. Streptococcus salivarius MS-oral-D6 promotes gingival re-epithelialization in vitro through a secreted serine protease.

    PubMed

    Fernandez-Gutierrez, Marcela M; Roosjen, Peter P J; Ultee, Eveline; Agelink, Maarten; Vervoort, Jacques J M; Keijser, Bart; Wells, Jerry M; Kleerebezem, Michiel

    2017-09-11

    Gingival re-epithelialization represents an essential phase of oral wound healing in which epithelial integrity is re-establish. We developed an automated high-throughput re-epithelialization kinetic model, using the gingival epithelial cell line Ca9-22. The model was employed to screen 39 lactic acid bacteria, predominantly including oral isolates, for their capacity to accelerate gingival re-epithelialization. This screen identified several strains of Streptococcus salivarius that stimulated re-epithelialization. Further analysis revealed that S. salivarius strain MS-oral-D6 significantly promoted re-epithelialization through a secreted proteinaceous compound and subsequent experiments identified a secreted serine protease as the most likely candidate to be involved in re-epithelialization stimulation. The identification of bacteria or their products that stimulate gingival wound repair may inspire novel strategies for the maintenance of oral health.

  1. Molecular epidemiology survey of penicillin-susceptible and -resistant Streptococcus pneumoniae recovered from patients with meningitis in France.

    PubMed

    Doit, C; Picard, B; Loukil, C; Geslin, P; Bingen, E

    2000-06-01

    The genetic diversity of Streptococcus pneumoniae isolates (n=291) recovered from cerebrospinal fluid of patients with meningitis in France was investigated by restriction fragment length polymorphism analysis of the ribosomal RNA gene regions and of the pbp2b and 2x genes. Statistical analysis of the data by factorial analysis of correspondence established the following: penicillin-susceptible isolates had a high level of genetic diversity, especially those belonging to serogroups frequently associated with carriage; capsular serotype switches could occur among penicillin-susceptible and -resistant isolates; and the mechanisms of acquired penicillin resistance were clearly distinct in isolates with penicillin minimum inhibitory concentration (MIC) values <1 mg/L and isolates with penicillin MIC values >/=1 mg/L. Thus, an increase in the penicillin MIC for a given strain, from intermediate to high-level resistance would be a rare event.

  2. Postantibiotic effects and postantibiotic sub-MIC effects of tilmicosin, erythromycin and tiamulin on erythromycin-resistant Streptococcus suis.

    PubMed

    Wang, Liping; Zhang, Yuanshu

    2009-10-01

    The postantibiotic effects (PAEs) and postantibiotic sub-MIC effects (PA SMEs) of tilmicosin, erythromycin and tiamulin on erythromycin-susceptible and erythromycin-resistant strains of Streptococcus suis (M phenotype) were investigated in vitro. Tilmicosin and tiamulin induced significantly longer PAE and PA SME against both erythromycin-susceptible and erythromycin-resistant strains than did erythromycin. The durations of PAE and PA SMEs were proportional to the concentrations of drugs used for exposure. The PA SMEs were substantially longer than PAEs on S. suis (P<0.05) regardless of the antimicrobial used for exposure. The results indicated that the PAE and PA SME could help in the design of efficient control strategies for infection especially caused by erythromycin-resistant S. suis and that they may provide additional valuable information for the rational drug use in clinical practice.

  3. Clonal Spread of Levofloxacin-Resistant Streptococcus pneumoniae Invasive Isolates in Madrid, Spain, 2007 to 2009▿

    PubMed Central

    Rodríguez-Avial, Iciar; Ramos, Belén; Ríos, Esther; Cercenado, Emilia; Ordobás, María; Sanz, Juan Carlos

    2011-01-01

    Among 1,349 Streptococcus pneumoniae invasive isolates, 45 (3.3%) were levofloxacin resistant. Serotype distribution was as follows: 8 (n = 32 isolates), 19A (n = 4 isolates), 7F (n = 3 isolates), 9V (n = 2 isolates), 10A (n = 1 isolate), 19F (n = 1 isolate), 6B (n = 1 isolate), and nontypeable (n = 1 isolate). Levofloxacin-resistant isolates had dual mutations in the gyrA and parC genes. Serotype 8 strains corresponded to a capsular switching of the Sweden15A-25 clone. Levofloxacin resistance was also detected among multiresistant (ST27619A, Spain9V-ST156, ST8819F, and ST15426B) and among usually antibiotic-susceptible (Netherlands7F-ST191, ST120119A, and ST263910A) clones. PMID:21383091

  4. Prevalence of mef and ermB genes in invasive pediatric erythromycin-resistant Streptococcus pneumoniae isolates from Argentina.

    PubMed

    Corso, A; Faccone, D; Gagetti, P; Pace, J; Regueira, M; Pace, Julio

    2009-01-01

    During the period 1993-2001, a total of 1,499 pneumococci isolates were recovered through the Argentinean surveillance of Streptococcus pneumoniae causing invasive disease in children under 6 years of age, 3.5% of which were erythromycin resistant. Among the 50 erythromycin-resistant strains available, 58% (n=29) harbored mefA/E genes (15 mefA, 30%; and 14 mefE, 28%), 34% (n=17) ermB, and 6% (n=3) both mefA/E plus ermB genes, while one isolate was negative for all the acquired genes studied. The England14-9 (42%), Poland6B-20 (20%) and Spain9V-3 (16%) clones were responsible for the emergence of pneumococcal macrolide resistance in pediatric population from Argentina.

  5. Characterization of antimicrobial resistance in Streptococcus pyogenes isolates from the San Francisco Bay area of northern California.

    PubMed

    York, M K; Gibbs, L; Perdreau-Remington, F; Brooks, G F

    1999-06-01

    During 1994 and 1995, 157 isolates of Streptococcus pyogenes from patients with invasive disease were consecutively collected in the San Francisco Bay area to determine the frequency of antimicrobial resistance. Susceptibility testing was performed according to the guidelines of the National Committee for Clinical Laboratory Standards by the disk method and by broth microdilution. For comparison of susceptibility patterns, an additional 149 strains were randomly collected from patients with pharyngitis. For San Francisco County, 32% of the isolates from invasive-disease-related specimens but only 9% of the isolates from throat cultures from the same period were resistant to erythromycin (P = 0.0007). Alameda County and Contra Costa County had rates of resistance of resistance (39%) among the strains from serious infections compared to those from other counties (P = <0. 0003). For tetracycline, high rates of resistance were observed in San Francisco County for both isolates from patients with invasive disease (34%) and pharyngitis (21%) in the same period. Using pulsed-field gel electrophoresis, two clones, one at the San Francisco County Hospital and a second in the entire area, were identified. The latter clone exhibited resistance to bacitracin. Of 146 strains that were tested by microdilution, all were susceptible to penicillin. Clindamycin resistance was not seen among the erythromycin-susceptible strains, but two of the 39 erythromycin-resistant strains were also resistant to clindamycin. An additional 34 strains showed resistance to clindamycin when exposed to an erythromycin disk in the double-disk diffusion test, suggesting that the mechanism of erythromycin resistance is due to an erm gene. This study demonstrates a high rate of resistance to macrolides and tetracycline among S. pyogenes isolates

  6. Identification of the Novel Lincosamide Resistance Gene lnu(E) Truncated by ISEnfa5-cfr-ISEnfa5 Insertion in Streptococcus suis: De Novo Synthesis and Confirmation of Functional Activity in Staphylococcus aureus

    PubMed Central

    Zhao, Qin; Wendlandt, Sarah; Li, Hui; Li, Jun; Wu, Congming; Shen, Jianzhong

    2014-01-01

    The novel lincosamide resistance gene lnu(E), truncated by insertion of an ISEnfa5-cfr-ISEnfa5 segment, was identified in Streptococcus suis. The gene lnu(E) encodes a 173-amino-acid protein with ≤69.4% identity to other lincosamide nucleotidyltransferases. The lnu(E) gene and its promoter region were de novo synthesized, and Staphylococcus aureus RN4220 carrying a shuttle vector with the cloned lnu(E) gene showed a 16-fold increase in the lincomycin MIC. Mass spectrometry experiments demonstrated that Lnu(E) catalyzed the nucleotidylation of lincomycin. PMID:24366733

  7. Cell Surface Glycoside Hydrolases of Streptococcus gordonii Promote Growth in Saliva

    PubMed Central

    Zhou, Yuan; Zhang, Luxia; Shah, Nehal; Palmer, Robert J.; Cisar, John O.

    2016-01-01

    ABSTRACT The growth of the oral commensal Streptococcus gordonii in saliva may depend on a number of glycoside hydrolases (GHs), including three cell wall-anchored proteins that are homologs of pneumococcal β-galactosidase (BgaA), β-N-acetylglucosaminidase (StrH), and endo-β-N-acetylglucosaminidase D (EndoD). In the present study, we introduced unmarked in-frame deletions into the corresponding genes of S. gordonii DL1, verified the presence (or absence) of the encoded proteins on the resulting mutant strains, and compared these strains with wild-type strain DL1 for growth and glycan foraging in saliva. The overnight growth of wild-type DL1 was reduced 3- to 10-fold by the deletion of any one or two genes and approximately 20-fold by the deletion of all three genes. The only notable change in the salivary proteome associated with this reduction of growth was a downward shift in the apparent molecular masses of basic proline-rich glycoproteins (PRG), which was accompanied by the loss of lectin binding sites for galactose-specific Erythrina cristagalli agglutinin (ECA) and mannose-specific Galanthus nivalis agglutinin (GNA). The binding of ECA to PRG was also abolished in saliva cultures of mutants that expressed cell surface BgaA alone or together with either StrH or EndoD. However, the subsequent loss of GNA binding was seen only in saliva cocultures of different mutants that together expressed all three cell surface GHs. The findings indicate that the growth of S. gordonii DL1 in saliva depends to a significant extent on the sequential actions of first BgaA and then StrH and EndoD on N-linked glycans of PRG. IMPORTANCE The ability of oral bacteria to grow on salivary glycoproteins is critical for dental plaque biofilm development. Little is known, however, about how specific salivary components are attacked and utilized by different members of the biofilm community, such as Streptococcus gordonii. Streptococcus gordonii DL1 has three cell wall

  8. Induction of prophages by fluoroquinolones in Streptococcus pneumoniae: implications for emergence of resistance in genetically-related clones.

    PubMed

    López, Elena; Domenech, Arnau; Ferrándiz, María-José; Frias, Maria João; Ardanuy, Carmen; Ramirez, Mario; García, Ernesto; Liñares, Josefina; de la Campa, Adela G

    2014-01-01

    Antibiotic resistance in Streptococcus pneumoniae has increased worldwide by the spread of a few clones. Fluoroquinolone resistance occurs mainly by alteration of their intracellular targets, the type II DNA topoisomerases, which is acquired either by point mutation or by recombination. Increase in fluoroquinolone-resistance may depend on the balance between antibiotic consumption and the cost that resistance imposes to bacterial fitness. In addition, pneumococcal prophages could play an important role. Prophage induction by fluoroquinolones was confirmed in 4 clinical isolates by using Southern blot hybridization. Clinical isolates (105 fluoroquinolone-resistant and 160 fluoroquinolone-susceptible) were tested for lysogeny by using a PCR assay and functional prophage carriage was studied by mitomycin C induction. Fluoroquinolone-resistant strains harbored fewer inducible prophages (17/43) than fluoroquinolone-susceptible strains (49/70) (P = 0.0018). In addition, isolates of clones associated with fluoroquinolone resistance [CC156 (3/25); CC63 (2/20), and CC81 (1/19)], had lower frequency of functional prophages than isolates of clones with low incidence of fluoroquinolone resistance [CC30 (4/21), CC230 (5/20), CC62 (9/21), and CC180 (21/30)]. Likewise, persistent strains from patients with chronic respiratory diseases subjected to fluoroquinolone treatment had a low frequency of inducible prophages (1/11). Development of ciprofloxacin resistance was tested with two isogenic strains, one lysogenic and the other non-lysogenic: emergence of resistance was only observed in the non-lysogenic strain. These results are compatible with the lysis of lysogenic isolates receiving fluoroquinolones before the development of resistance and explain the inverse relation between presence of inducible prophages and fluoroquinolone-resistance.

  9. Induction of Prophages by Fluoroquinolones in Streptococcus pneumoniae: Implications for Emergence of Resistance in Genetically-Related Clones

    PubMed Central

    Ferrándiz, María-José; Frias, Maria João; Ardanuy, Carmen; Ramirez, Mario; García, Ernesto; Liñares, Josefina; de la Campa, Adela G.

    2014-01-01

    Antibiotic resistance in Streptococcus pneumoniae has increased worldwide by the spread of a few clones. Fluoroquinolone resistance occurs mainly by alteration of their intracellular targets, the type II DNA topoisomerases, which is acquired either by point mutation or by recombination. Increase in fluoroquinolone-resistance may depend on the balance between antibiotic consumption and the cost that resistance imposes to bacterial fitness. In addition, pneumococcal prophages could play an important role. Prophage induction by fluoroquinolones was confirmed in 4 clinical isolates by using Southern blot hybridization. Clinical isolates (105 fluoroquinolone-resistant and 160 fluoroquinolone-susceptible) were tested for lysogeny by using a PCR assay and functional prophage carriage was studied by mitomycin C induction. Fluoroquinolone-resistant strains harbored fewer inducible prophages (17/43) than fluoroquinolone-susceptible strains (49/70) (P = 0.0018). In addition, isolates of clones associated with fluoroquinolone resistance [CC156 (3/25); CC63 (2/20), and CC81 (1/19)], had lower frequency of functional prophages than isolates of clones with low incidence of fluoroquinolone resistance [CC30 (4/21), CC230 (5/20), CC62 (9/21), and CC180 (21/30)]. Likewise, persistent strains from patients with chronic respiratory diseases subjected to fluoroquinolone treatment had a low frequency of inducible prophages (1/11). Development of ciprofloxacin resistance was tested with two isogenic strains, one lysogenic and the other non-lysogenic: emergence of resistance was only observed in the non-lysogenic strain. These results are compatible with the lysis of lysogenic isolates receiving fluoroquinolones before the development of resistance and explain the inverse relation between presence of inducible prophages and fluoroquinolone-resistance. PMID:24718595

  10. Replication of type 5 adenovirus promotes middle ear infection by Streptococcus pneumoniae in the chinchilla model of otitis media

    PubMed Central

    Murrah, Kyle A.; Turner, Roberta L.; Pang, Bing; Perez, Antonia C.; Reimche, Jennifer L.; King, Lauren B.; Wren, John; Gandhi, Uma; Swords, W. Edward; Ornelles, David A.

    2015-01-01

    Adenoviral infection is a major risk factor for otitis media. We hypothesized that adenovirus promotes bacterial ascension into the middle ear through the disruption of normal function in the Eustachian tubes due to inflammation-induced changes. An intranasal infection model of the chinchilla was used to test the ability of type 5 adenovirus to promote middle ear infection by Streptococcus pneumoniae. The hyperinflammatory adenovirus mutant dl327 and the nonreplicating adenovirus mutant H5wt300ΔpTP were used to test the role of inflammation and viral replication, respectively, in promotion of pneumococcal middle ear infection. Precedent infection with adenovirus resulted in a significantly greater incidence of middle ear disease by S. pneumoniae as compared to nonadenovirus infected animals. Infection with the adenovirus mutant dl327 induced a comparable degree of bacterial ascension into the middle ear as did infection with the wild-type virus. By contrast, infection with the nonreplicating adenovirus mutant H5wt300ΔpTP resulted in less extensive middle ear infection compared to the wild-type adenovirus. We conclude that viral replication is necessary for adenoviral-induced pneumococcal middle ear disease. PMID:25251686

  11. Local changes in rates of group A Streptococcus disease and antibiotic resistance are associated with geographically widespread strain turnover events.

    PubMed

    Metzgar, David; McDonough, Erin A; Hansen, Christian J; Blaesing, Carl R; Baynes, Darcie; Hawksworth, Anthony W; Blair, Patrick J; Faix, Dennis J; Russell, Kevin L

    2010-01-01

    This study addresses the effects of dynamic strain turnover and antibiotic prophylaxis on rates of group A Streptococcus (GAS) antibiotic resistance and disease. The authors analyzed the strain distributions, disease rates, and patterns of antibiotic resistance of 802 GAS isolates collected from 2002 through 2007. These samples were collected from patients with GAS infection symptoms at 10 military facilities. Macrolide resistance peaked at 25% during 2004, due to the geographically widespread dominance of a single resistant strain (M75). The resistant strain was not retained regardless of local patterns of macrolide use, and resistance rates decreased upon replacement of M75 with macrolide-susceptible strains. Disease rates were similarly correlated with dominance of specific M types. Statistical analysis revealed temporal correlations between strain distributions at multiple locations. Only the most common strains yielded enough data at multiple sites for statistically significant comparison of temporal fluctuations in dominance, but these (including M44, M3, M18, M118, and M6) all yielded highly significant temporal correlations of 90% or greater on yearly scales. As expected given the complexity and variability of strain distributions on shorter time scales, analysis on a monthly scale yielded lower degrees of positive correlation (31-62%), but in this case all significant correlations were still positive. Shifts in antibiotic resistance profiles and disease rates at specific sites appear to be associated with strain replacements happening on larger scales, independent of antibiotic use at individual sites.

  12. The selection of resistance to and the mutagenicity of different fluoroquinolones in Staphylococcus aureus and Streptococcus pneumoniae.

    PubMed

    Sierra, J M; Cabeza, J G; Ruiz Chaler, M; Montero, T; Hernandez, J; Mensa, J; Llagostera, M; Vila, J

    2005-09-01

    Two quinolone-susceptible Staphylococcus aureus and five quinolone-susceptible Streptococcus pneumoniae isolates were used to obtain in-vitro quinolone-resistant mutants in a multistep resistance selection process. The fluoroquinolones used were ciprofloxacin, moxifloxacin, levofloxacin, gemifloxacin, trovafloxacin and clinafloxacin. The mutagenicity of these quinolones was determined by the Salmonella and the Escherichia coli retromutation assays. All quinolone-resistant Staph. aureus mutants had at least one mutation in the grlA gene, while 86.6% of quinolone-resistant Strep. pneumoniae mutants had mutations in either or both the gyrA and parC genes. Moxifloxacin and levofloxacin selected resistant mutants later than the other quinolones, but this difference was more obvious in Staph. aureus. Accumulation of the fluoroquinolones by Staph. aureus did not explain these differences, since levofloxacin and moxifloxacin accumulated inside bacteria to the same extent as clinafloxacin and trovafloxacin. The results also showed that moxifloxacin and levofloxacin had less mutagenic potency in both mutagenicity assays, suggesting a possible relationship between the selection of resistance to quinolones and the mutagenic potency of the molecule. Furthermore, gemifloxacin selected efflux mutants more frequently than the other quinolones used. Thus, the risk of developing quinolone resistance may depend on the density of the microorganism at the infection site and the concentration of the fluoroquinolone, and also on the mutagenicity of the quinolone used, with moxifloxacin and levofloxacin being the least mutagenic.

  13. High clonal diversity in erythromycin-resistant Streptococcus pneumoniae invasive isolates in Madrid, Spain (2000-07).

    PubMed

    de la Pedrosa, Elia Gómez G; Baquero, Fernando; Loza, Elena; Nadal-Serrano, José-María; Fenoll, Asunción; Del Campo, Rosa; Cantón, Rafael

    2009-12-01

    Erythromycin resistance in Streptococcus pneumoniae is still increasing worldwide. All 78 erythromycin-resistant S. pneumoniae isolates collected from blood cultures in our hospital (2000-07) were studied and the population structure was analysed by using different mathematical diversity indexes. Erythromycin resistance determinants were screened by PCR. The population structure, including multilocus sequence typing, was analysed by using quantitative clonal diversity (diversity ratio, Simpson, Selander-Levin and Shannon mathematical indexes). The leading resistance gene was erm(B) (74.3% of the isolates), followed by the erm(B) plus mef(A) combination (17.9%) and mef(A) alone (7.7%). The most frequent serotypes were 14 (18%), 19A (15.4%) and 6B (11.5%). A polyclonal structure was detected in resistant strains, including the Spain(9V)-3, Spain(6B)-2 and Denmark(14)-32 international clones. Both genetic diversity and genetic distribution were high, particularly among clones containing erm(B) and erm(B) plus mef(A) determinants. The resistance determinants erm(B) and the combination of erm(B) plus mef(A) were observed within multiple S. pneumoniae bacteraemic clones. The preservation of a polyclonal structure might provide a suitable background for further evolution of antibiotic resistance.

  14. Multiple mutations and increased RNA expression in tetracycline-resistant Streptococcus pneumoniae as determined by genome-wide DNA and mRNA sequencing.

    PubMed

    Lupien, Andréanne; Gingras, Hélène; Bergeron, Michel G; Leprohon, Philippe; Ouellette, Marc

    2015-07-01

    The objective of this study was to characterize chromosomal mutations associated with resistance to tetracycline in Streptococcus pneumoniae. Chronological appearance of mutations in two S. pneumoniae R6 mutants (R6M1TC-5 and R6M2TC-4) selected for resistance to tetracycline was determined by next-generation sequencing. A role for the mutations identified was confirmed by reconstructing resistance to tetracycline in a S. pneumoniae R6 WT background. RNA sequencing was performed on R6M1TC-5 and R6M2TC-4 and the relative expression of genes was reported according to R6. Differentially expressed genes were classified according to their ontology. WGS of R6M1TC-5 and R6M2TC-4 revealed mutations in the gene rpsJ coding for the ribosomal protein S10 and in the promoter region and coding sequences of the ABC genes patA and patB. These cells were cross-resistant to ciprofloxacin. Resistance reconstruction confirmed a role in resistance for the mutations in rpsJ and patA. Overexpression of the ABC transporter PatA/PatB or mutations in the coding sequence of patA contributed to resistance to tetracycline, ciprofloxacin and ethidium bromide, and was associated with a decreased accumulation of [(3)H]tetracycline. Comparative transcriptome profiling of the resistant mutants further revealed that, in addition to the overexpression of patA and patB, several genes of the thiamine biosynthesis and salvage pathway were increased in the two mutants, but also in clinical isolates resistant to tetracycline. This overexpression most likely contributes to the tetracycline resistance phenotype. The combination of genomic and transcriptomic analysis coupled to functional studies has allowed the discovery of novel tetracycline resistance mutations in S. pneumoniae. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Genomic Characterization of Ciprofloxacin Resistance in a Laboratory-Derived Mutant and a Clinical Isolate of Streptococcus pneumoniae

    PubMed Central

    Lupien, Andréanne; Billal, Dewan S.; Fani, Fereshteh; Soualhine, Hafid; Zhanel, George G.; Leprohon, Philippe

    2013-01-01

    The broad-spectrum fluoroquinolone ciprofloxacin is a bactericidal antibiotic targeting DNA topoisomerase IV and DNA gyrase encoded by the parC and gyrA genes. Resistance to ciprofloxacin in Streptococcus pneumoniae mainly occurs through the acquisition of mutations in the quinolone resistance-determining region (QRDR) of the ParC and GyrA targets. A role in low-level ciprofloxacin resistance has also been attributed to efflux systems. To look into ciprofloxacin resistance at a genome-wide scale and to discover additional mutations implicated in resistance, we performed whole-genome sequencing of an S. pneumoniae isolate selected for resistance to ciprofloxacin in vitro (128 μg/ml) and of a clinical isolate displaying low-level ciprofloxacin resistance (2 μg/ml). Gene disruption and DNA transformation experiments with PCR fragments harboring the mutations identified in the in vitro S. pneumoniae mutant revealed that resistance is mainly due to QRDR mutations in parC and gyrA and to the overexpression of the ABC transporters PatA and PatB. In contrast, no QRDR mutations were identified in the genome of the S. pneumoniae clinical isolate with low-level resistance to ciprofloxacin. Assays performed in the presence of the efflux pump inhibitor reserpine suggested that resistance is likely mediated by efflux. Interestingly, the genome sequence of this clinical isolate also revealed mutations in the coding region of patA and patB that we implicated in resistance. Finally, a mutation in the NAD(P)H-dependent glycerol-3-phosphate dehydrogenase identified in the S. pneumoniae clinical strain was shown to protect against ciprofloxacin-mediated reactive oxygen species. PMID:23877698

  16. Single- and multistep resistance selection studies on the activity of retapamulin compared to other agents against Staphylococcus aureus and Streptococcus pyogenes.

    PubMed

    Kosowska-Shick, Klaudia; Clark, Catherine; Credito, Kim; McGhee, Pamela; Dewasse, Bonifacio; Bogdanovich, Tatiana; Appelbaum, Peter C

    2006-02-01

    Retapamulin had the lowest rate of spontaneous mutations by single-step passaging and the lowest parent and selected mutant MICs by multistep passaging among all drugs tested for all Staphylococcus aureus strains and three Streptococcus pyogenes strains which yielded resistant clones. Retapamulin has a low potential for resistance selection in S. pyogenes, with a slow and gradual propensity for resistance development in S. aureus.

  17. Single- and Multistep Resistance Selection Studies on the Activity of Retapamulin Compared to Other Agents against Staphylococcus aureus and Streptococcus pyogenes

    PubMed Central

    Kosowska-Shick, Klaudia; Clark, Catherine; Credito, Kim; McGhee, Pamela; Dewasse, Bonifacio; Bogdanovich, Tatiana; Appelbaum, Peter C.

    2006-01-01

    Retapamulin had the lowest rate of spontaneous mutations by single-step passaging and the lowest parent and selected mutant MICs by multistep passaging among all drugs tested for all Staphylococcus aureus strains and three Streptococcus pyogenes strains which yielded resistant clones. Retapamulin has a low potential for resistance selection in S. pyogenes, with a slow and gradual propensity for resistance development in S. aureus. PMID:16436741

  18. Streptolysin S Promotes Programmed Cell Death and Enhances Inflammatory Signaling in Epithelial Keratinocytes during Group A Streptococcus Infection

    PubMed Central

    Flaherty, Rebecca A.; Puricelli, Jessica M.; Higashi, Dustin L.; Park, Claudia J.

    2015-01-01

    Streptococcus pyogenes, or group A Streptococcus (GAS), is a pathogen that causes a multitude of human diseases from pharyngitis to severe infections such as toxic shock syndrome and necrotizing fasciitis. One of the primary virulence factors produced by GAS is the peptide toxin streptolysin S (SLS). In addition to its well-recognized role as a cytolysin, recent evidence has indicated that SLS may influence host cell signaling pathways at sublytic concentrations during infection. We employed an antibody array-based approach to comprehensively identify global host cell changes in human epithelial keratinocytes in response to the SLS toxin. We identified key SLS-dependent host responses, including the initiation of specific programmed cell death and inflammatory cascades with concomitant downregulation of Akt-mediated cytoprotection. Significant signaling responses identified by our array analysis were confirmed using biochemical and protein identification methods. To further demonstrate that the observed SLS-dependent host signaling changes were mediated primarily by the secreted toxin, we designed a Transwell infection system in which direct bacterial attachment to host cells was prevented, while secreted factors were allowed access to host cells. The results using this approach were consistent with our direct infection studies and reveal that SLS is a bacterial toxin that does not require bacterial attachment to host cells for activity. In light of these findings, we propose that the production of SLS by GAS during skin infection promotes invasive outcomes by triggering programmed cell death and inflammatory cascades in host cells to breach the keratinocyte barrier for dissemination into deeper tissues. PMID:26238711

  19. Streptolysin S Promotes Programmed Cell Death and Enhances Inflammatory Signaling in Epithelial Keratinocytes during Group A Streptococcus Infection.

    PubMed

    Flaherty, Rebecca A; Puricelli, Jessica M; Higashi, Dustin L; Park, Claudia J; Lee, Shaun W

    2015-10-01

    Streptococcus pyogenes, or group A Streptococcus (GAS), is a pathogen that causes a multitude of human diseases from pharyngitis to severe infections such as toxic shock syndrome and necrotizing fasciitis. One of the primary virulence factors produced by GAS is the peptide toxin streptolysin S (SLS). In addition to its well-recognized role as a cytolysin, recent evidence has indicated that SLS may influence host cell signaling pathways at sublytic concentrations during infection. We employed an antibody array-based approach to comprehensively identify global host cell changes in human epithelial keratinocytes in response to the SLS toxin. We identified key SLS-dependent host responses, including the initiation of specific programmed cell death and inflammatory cascades with concomitant downregulation of Akt-mediated cytoprotection. Significant signaling responses identified by our array analysis were confirmed using biochemical and protein identification methods. To further demonstrate that the observed SLS-dependent host signaling changes were mediated primarily by the secreted toxin, we designed a Transwell infection system in which direct bacterial attachment to host cells was prevented, while secreted factors were allowed access to host cells. The results using this approach were consistent with our direct infection studies and reveal that SLS is a bacterial toxin that does not require bacterial attachment to host cells for activity. In light of these findings, we propose that the production of SLS by GAS during skin infection promotes invasive outcomes by triggering programmed cell death and inflammatory cascades in host cells to breach the keratinocyte barrier for dissemination into deeper tissues. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  20. Nosocomial Outbreak of Drug-Resistant Streptococcus pneumoniae Serotype 9V in an Adult Respiratory Medicine Ward

    PubMed Central

    Khan-Orakzai, Zareena; Kapatai, Georgia; Bloch, Susannah; Singleton, Julie; Atkin, Sara; Shah, Victoria; Hatcher, James; Samarasinghe, Dunisha; Sheppard, Carmen

    2016-01-01

    ABSTRACT Streptococcus pneumoniae infections arising in hospitalized patients are often assumed to be sporadic and linked to community acquisition. Here, whole-genome sequencing was used to demonstrate nosocomial acquisition of antimicrobial-resistant sequence type 156 (ST156) serotype 9V S. pneumoniae in 3 respiratory patients that resulted in two bacteremias and one lower respiratory tract infection. Two of the cases arose in patients who had recently been discharged from the hospital and were readmitted from the community. Nosocomial spread was suspected solely because of the highly unusual resistance pattern and case presentations within 24 h of one another. The outbreak highlights the potential for rapid transmission and the short incubation period in the respiratory ward setting. PMID:27974539

  1. Nosocomial Outbreak of Drug-Resistant Streptococcus pneumoniae Serotype 9V in an Adult Respiratory Medicine Ward.

    PubMed

    Jauneikaite, Elita; Khan-Orakzai, Zareena; Kapatai, Georgia; Bloch, Susannah; Singleton, Julie; Atkin, Sara; Shah, Victoria; Hatcher, James; Samarasinghe, Dunisha; Sheppard, Carmen; Fry, Norman K; Satta, Giovanni; Sriskandan, Shiranee

    2017-03-01

    Streptococcus pneumoniae infections arising in hospitalized patients are often assumed to be sporadic and linked to community acquisition. Here, whole-genome sequencing was used to demonstrate nosocomial acquisition of antimicrobial-resistant sequence type 156 (ST156) serotype 9V S. pneumoniae in 3 respiratory patients that resulted in two bacteremias and one lower respiratory tract infection. Two of the cases arose in patients who had recently been discharged from the hospital and were readmitted from the community. Nosocomial spread was suspected solely because of the highly unusual resistance pattern and case presentations within 24 h of one another. The outbreak highlights the potential for rapid transmission and the short incubation period in the respiratory ward setting. Copyright © 2017 Jauneikaite et al.

  2. Rise of multidrug-resistant non-vaccine serotype 15A Streptococcus pneumoniae in the United Kingdom, 2001 to 2014

    PubMed Central

    Sheppard, Carmen; Fry, Norman K.; Mushtaq, Shazad; Woodford, Neil; Reynolds, Rosy; Janes, Regina; Pike, Rachel; Hill, Robert; Kimuli, Maimuna; Staves, Peter; Doumith, Michel; Harrison, Timothy; Livermore, David M

    2016-01-01

    Conjugate vaccines have reduced pneumococcal disease in vaccinated children and unvaccinated adults, but non-vaccine serotypes are of concern, particularly if antibiotic resistant. We reviewed Streptococcus pneumoniae collected via: (i) the British Society for Antimicrobial Chemotherapy (BSAC) surveillances from 2001–2014; (ii) Public Health England’s (PHE) invasive isolate surveillance from 2005–2014 and (iii) referral to PHE for resistance investigation from 2005–2014. Serotype 15A increased in all series, with many representatives showing triple resistance to macrolides, tetracyclines and penicillin. 15A was consistently among the 10 most prevalent serotypes from 2011 in PHE and BSAC invasive isolate/bacteraemia surveillance but never previously; 26–33% of these invasive 15A isolates had triple resistance. BSAC respiratory isolates were only serotyped in 2013/14 and 2014/15 (October to September); 15A was most prevalent serotype in both periods, comprising 9–11% of isolates, 38–48% of them with triple resistance. Serotype 15A represented 0–4% of S. pneumoniae referred to PHE for reference investigation annually until 2008 but rose to 29% (2013) and 32% (2014). Almost all multidrug-resistant 15A isolates were sequence type (ST) 63 variants, whereas susceptible 15A isolates were clonally diverse. The rise of serotype 15A suggests that pneumococcal conjugate vaccines will need ongoing adaptation. PMID:28006650

  3. Rapidly Increasing Prevalence of Penicillin-Resistant Streptococcus pneumoniae in Middle Tennessee: a 10-Year Clinical and Molecular Analysis

    PubMed Central

    Tang, Yi-Wei; Li, Haijing; Griffin, Jane P.; Haas, David W.; D'Agata, Erika M. C.

    2002-01-01

    The clinical and molecular epidemiology of penicillin-resistant Streptococcus pneumoniae and the diagnostic accuracy of a six-primer PCR assay in identifying penicillin resistance were analyzed by using clinical isolates recovered over a 10-year period in middle Tennessee. The prevalence of non-penicillin-susceptible S. pneumoniae isolates (MIC, ≥0.1 μg/ml) increased from 10% in 1990 to 70% in 1999 (P < 0.001). Among S. pneumoniae isolates for which the penicillin MIC was ≥2 μg/ml (highly penicillin-resistant S. pneumoniae [PRSP]), 23 and 5% were resistant to at least three and at least five other antimicrobial classes, respectively. Pulsed-field gel electrophoresis identified 13 unique strain types, with type B accounting for 33% of PRSP isolates. The sensitivity, specificity, and negative and positive predictive values of the PCR assay in detecting PRSP were 99, 100, 99, and 100%, respectively. Penicillin resistance is rapidly increasing among S. pneumoniae isolates in Tennessee. The simultaneous detection of S. pneumoniae and high-level penicillin resistance can be accurately performed with the six-primer PCR assay. PMID:11825948

  4. Efficacy of moxifloxacin for treatment of penicillin-, macrolide- and multidrug-resistant Streptococcus pneumoniae in community-acquired pneumonia.

    PubMed

    Fogarty, C; Torres, A; Choudhri, S; Haverstock, D; Herrington, J; Ambler, J

    2005-11-01

    This pooled analysis of six prospective, multicentre trials aimed to determine the efficacy of moxifloxacin in community-acquired pneumonia (CAP) due to penicillin-, macrolide- and multidrug-resistant Streptococcus pneumoniae (MDRSP). At a central laboratory, isolates were identified and antimicrobial susceptibility determined (microbroth dilution). MDRSP was defined as resistance > or =3 drug classes. Patients received oral or sequential intravenous/oral 400 mg moxifloxacin once daily for 7-14 days. The primary endpoint was clinical success at test-of-cure for efficacy-valid patients with proven pretherapy S. pneumoniae infection. Of 140 S. pneumoniae isolated (112 respiratory, 28 blood), 23 (16.4%) were penicillin resistant, 26 (18.6%) macrolide resistant and 31 (22.1%) MDRSP. The moxifloxacin MIC90 was 0.25 microg/ml. Clinical cure with moxifloxacin was 95.4% (125/131) overall, and 100% (21/21) for penicillin-, 95.7% (22/23) for macrolide- and 96.4% (27/28) for multidrug-resistant strains. Moxifloxacin provided excellent clinical and bacteriological cure rates in CAP due to drug-resistant pneumococci.

  5. Erythromycin resistance in italian isolates of Streptococcus pyogenes and correlations with pulsed-field gel electrophoresis analysis.

    PubMed

    Zampaloni, Claudia; Vitali, Luca A; Prenna, Manuela; Toscano, Maria A; Tempera, Gianna; Ripa, Sandro

    2002-01-01

    Erythromycin resistance among Streptococcus pyogenes strains has been reported in Italy at high rates during the last few years. A total of 152 erythromycin-resistant isolates of this species from southern Italian regions were characterized for the macrolide-resistance phenotype and screened by PCR for the corresponding genetic determinant. A close correlation was found between these phenotypic/genotypic data concerning macrolide resistance and results of Sma I macrorestriction fragment patterns (PFGE) analysis. In fact, the vast majority of the isolates assigned to individual PFGE classes mostly belonged to a single phenotype of macrolide resistance. All untypeable isolates belonged to the M phenotype. Twenty-two distinct PFGE types were recognized, of which 11 were recorded in only one isolate (one-strain type); about 50% of typeable isolates fell into five type clusters and 70% in seven. The increased erythromycin resistance among Italian isolates of S. pyogenes does not appear to be due to the spread of a single clone, but results indicate that the majority of group A streptococci examined are probably spread from a limited number of clones.

  6. The Effect of Macrolide Resistance on the Presentation and Outcome of Patients Hospitalized for Streptococcus pneumoniae Pneumonia.

    PubMed

    Cilloniz, Catia; Albert, Richard K; Liapikou, Adamanthia; Gabarrus, Albert; Rangel, Ernesto; Bello, Salvador; Marco, Francesc; Mensa, Josep; Torres, Antoni

    2015-06-01

    There are conflicting reports describing the effect of macrolide resistance on the presentation and outcomes of patients with Streptococcus pneumoniae pneumonia. We aimed to determine the effect of macrolide resistance on the presentation and outcomes of patients with pneumococcal pneumonia. We conducted a retrospective, observational study in the Hospital Clinic of Barcelona of all adult patients hospitalized with pneumonia who had positive cultures for S. pneumoniae from January 1, 2000 to December 31, 2013. Outcomes examined included bacteremia, pulmonary complications, acute renal failure, shock, intensive care unit admission, need for mechanical ventilation, length of hospital stay, and 30-day mortality. Of 643 patients hospitalized for S. pneumoniae pneumonia, 139 (22%) were macrolide resistant. Patients with macrolide-resistant organisms were less likely to have bacteremia, pulmonary complications, and shock, and were less likely to require noninvasive mechanical ventilation. We found no increase in the incidence of acute renal failure, the frequency of intensive care unit admission, the need for invasive ventilatory support, the length of hospital stay, or the 30-day mortality in patients with (invasive or noninvasive) macrolide-resistant S. pneumoniae pneumonia, and no effect on outcomes as a function of whether treatment regimens did or did not comply with current guidelines. We found no evidence suggesting that patients hospitalized for macrolide-resistant S. pneumoniae pneumonia were more severely ill on presentation or had worse clinical outcomes if they were treated with guideline-compliant versus noncompliant regimens.

  7. Antibiotic dose impact on resistance selection in the community: a mathematical model of beta-lactams and Streptococcus pneumoniae dynamics.

    PubMed

    Opatowski, Lulla; Mandel, Jonas; Varon, Emmanuelle; Boëlle, Pierre-Yves; Temime, Laura; Guillemot, Didier

    2010-06-01

    Streptococcus pneumoniae is a major pathogen in the community and presents high rates of resistance to the available antibiotics. To prevent antibiotic treatment failure caused by highly resistant bacteria, increasing the prescribed antibiotic dose has recently been suggested. The aim of the present study was to assess the influence of beta-lactam prescribed doses on the emergence of resistance and selection in the community. A mathematical model was constructed by combining S. pneumoniae pharmacodynamic and population-dynamic approaches. The received-dose heterogeneity in the population was specifically modeled. Simulations over a 50-year period were run to test the effects of dose distribution and antibiotic exposure frequency changes on community resistance patterns, as well as the accuracy of the defined daily dose as a predictor of resistance. When the frequency of antibiotic exposure per year was kept constant, dose levels had a strong impact on the levels of resistance after a 50-year simulation. The lowest doses resulted in a high prevalence of nonsusceptible strains (> or =70%) with MICs that were still low (1 mg/liter), whereas high doses resulted in a lower prevalence of nonsusceptible strains (<40%) and higher MICs (2 mg/liter). Furthermore, by keeping the volume of antibiotics constant in the population, different patterns of use (low antibiotic dose and high antibiotic exposure frequency versus high dose and low frequency) could lead to markedly different rates of resistance distribution and prevalence (from 10 to 100%). Our results suggest that pneumococcal resistance patterns in the community are strongly related to the individual beta-lactam doses received: limiting beta-lactam use while increasing the doses could help reduce the prevalence of resistance, although it should select for higher levels of resistance. Surveillance networks are therefore encouraged to collect both daily antibiotic exposure frequencies and individual prescribed doses.

  8. Bacteraemia due to Streptococcus gallolyticus subspecies pasteurianus is associated with digestive tract malignancies and resistance to macrolides and clindamycin.

    PubMed

    Sheng, Wang-Huei; Chuang, Yu-Chung; Teng, Lee-Jene; Hsueh, Po-Ren

    2014-08-01

    This study was intended to delineate the association between digestive tract malignancies and bacteraemia due to Streptococcus gallolyticus subspecies pasteurianus. We reviewed the medical records and microbiological results of patients with bacteraemia due to Streptococcus bovis during the period 2000-2012. Species and subspecies identification of isolates originally classified as S. bovis was confirmed by 16S rRNA sequencing and PCR restriction fragment length polymorphism (PCR-RFLP) assays. Minimum inhibitory concentrations of antimicrobial agents were determined by the broth microdilution method. Of the 172 S. bovis complex isolates obtained from 172 patients (age range, <1-94 years, median age, 66) with bacteraemia, 31 isolates were identified to be S. gallolyticus subspecies gallolyticus, 126 were S. gallolyticus subspecies pasteurianus, and 15 were shown to be Streptococcus infantarius. The majority (n = 104, 60%) of patients were male and had underlying malignancies (n = 87, 51%). Bacteraemia due to S. gallolyticus subspecies gallolyticus was significantly associated with endocarditis while S. gallolyticus subspecies pasteurianus was more likely to be associated with malignancies of the digestive tract, including gastric, pancreatic, hepatobiliary and colorectal cancers. Septic shock at presentation was the only factor associated with mortality among patients with bacteraemia due to either subspecies of S. bovis. Isolates of S. gallolyticus subspecies pasteurianus had higher rates of resistance to macrolides and clindamycin than isolates of S. gallolyticus subspecies gallolyticus. Extensive diagnostic work-up for digestive tract malignancies and trans-esophageal echocardiogram should be investigated in patients with bacteraemia caused by S. gallolyticus. Copyright © 2014 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

  9. Host-derived extracellular RNA promotes adhesion of Streptococcus pneumoniae to endothelial and epithelial cells

    PubMed Central

    Zakrzewicz, Dariusz; Bergmann, Simone; Didiasova, Miroslava; Giaimo, Benedetto Daniele; Borggrefe, Tilman; Mieth, Maren; Hocke, Andreas C.; Lochnit, Guenter; Schaefer, Liliana; Hammerschmidt, Sven; Preissner, Klaus T.; Wygrecka, Malgorzata

    2016-01-01

    Streptococcus pneumoniae is the most frequent cause of community-acquired pneumonia. The infection process involves bacterial cell surface receptors, which interact with host extracellular matrix components to facilitate colonization and dissemination of bacteria. Here, we investigated the role of host-derived extracellular RNA (eRNA) in the process of pneumococcal alveolar epithelial cell infection. Our study demonstrates that eRNA dose-dependently increased S. pneumoniae invasion of alveolar epithelial cells. Extracellular enolase (Eno), a plasminogen (Plg) receptor, was identified as a novel eRNA-binding protein on S. pneumoniae surface, and six Eno eRNA-binding sites including a C-terminal 15 amino acid motif containing lysine residue 434 were characterized. Although the substitution of lysine 434 for glycine (K434G) markedly diminished the binding of eRNA to Eno, the adherence to and internalization into alveolar epithelial cells of S. pneumoniae strain carrying the C-terminal lysine deletion and the mutation of internal Plg-binding motif were only marginally impaired. Accordingly, using a mass spectrometric approach, we identified seven novel eRNA-binding proteins in pneumococcal cell wall. Given the high number of eRNA-interacting proteins on pneumococci, treatment with RNase1 completely inhibited eRNA-mediated pneumococcal alveolar epithelial cell infection. Our data support further efforts to employ RNAse1 as an antimicrobial agent to combat pneumococcal infectious diseases. PMID:27892961

  10. Interaction of fibrinogen and muramidase-released protein promotes the development of Streptococcus suis meningitis

    PubMed Central

    Wang, Junping; Kong, Decong; Zhang, Shengwei; Jiang, Hua; Zheng, Yuling; Zang, Yating; Hao, Huaijie; Jiang, Yongqiang

    2015-01-01

    Muramidase-released protein (MRP) is as an important virulence marker of Streptococcus suis (S. suis) serotype 2. Our previous works have shown that MRP can bind human fibrinogen (hFg); however, the function of this interaction in S. suis meningitis is not known. In this study, we found that the deletion of mrp significantly impairs the hFg-mediated adherence and traversal ability of S. suis across human cerebral microvascular endothelial cells (hCMEC/D3). Measurement of the permeability to Lucifer yellow in vitro and Evans blue extravasation in vivo show that the MRP-hFg interaction significantly increases the permeability of the blood–brain barrier (BBB). In the mouse meningitis model, wild type S. suis caused higher bacterial loads in the brain and more severe histopathological signs of meningitis than the mrp mutant at day 3 post-infection. Western blot analysis and immunofluorescence observations reveal that the MRP-hFg interaction can destroy the cell adherens junction protein p120-catenin of hCMEC/D3. These results indicate that the MRP-hFg interaction is important in the development of S. suis meningitis. PMID:26441928

  11. Pili of oral Streptococcus sanguinis bind to salivary amylase and promote the biofilm formation.

    PubMed

    Okahashi, Nobuo; Nakata, Masanobu; Terao, Yutaka; Isoda, Ryutaro; Sakurai, Atsuo; Sumitomo, Tomoko; Yamaguchi, Masaya; Kimura, Richard K; Oiki, Eiji; Kawabata, Shigetada; Ooshima, Takashi

    2011-01-01

    Streptococcus sanguinis is a member of oral streptococci and one of the most abundant species found in oral biofilm called dental plaque. Colonization of the oral streptococci on the tooth surface depends on the adhesion of bacteria to salivary components adsorbed to the tooth surface. Recently, we identified unique cell surface long filamentous structures named pili in this species. Herein, we investigated the role of S. sanguinis pili in biofilm formation. We found that pili-deficient mutant, in which the genes encoding the three pilus proteins PilA, PilB and PilC have been deleted, showed an impaired bacterial accumulation on saliva-coated surfaces. Confocal microscopic observations suggested that the mutant was incapable of producing typical three-dimensional layer of biofilm. Ligand blot analysis showed that the ancillary pilus proteins PilB and PilC bound to human whole saliva. Additional analysis demonstrated that PilC bound to multiple salivary components, and one of which was found to be salivary α-amylase. These results indicate that pilus proteins are members of saliva-binding proteins of oral S. sanguinis, and suggest the involvement of pili in its colonization on saliva-coated tooth surfaces and in the human oral cavity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Nicotine promotes Streptococcus mutans extracellular polysaccharide synthesis, cell aggregation and overall lactate dehydrogenase activity.

    PubMed

    Huang, R; Li, M; Gregory, R L

    2015-08-01

    Several epidemiology studies have reported a positive relationship between smoking and dental caries. Nicotine, an alkaloid component of tobacco, has been demonstrated to stimulate biofilm formation and metabolic activity of Streptococcus mutans, one of the most important pathogens of dental caries. The first aim of the present study was to explore the possible mechanisms leading to increased biofilm by nicotine treatment from three aspects, extracellular polysaccharides (EPS) synthesis, glucosyltransferase (Gtf) synthesis and glucan-binding protein (Gbp) synthesis at the mRNA and protein levels. The second aim was to investigate how nicotine affects S. mutans virulence, particular in lactate dehydrogenase (LDH) activity. Confocal laser scanning microscopy results demonstrated that both biofilm bacterial cell numbers and EPS were increased by nicotine. Gtf and GbpA protein expression of S. mutans planktonic cells were upregulated while GbpB protein expression of biofilm cells were downregulated by nicotine. The mRNA expression trends of those genes were mostly consistent with results on protein level but not statistically significant, and gtfD and gbpD of biofilm cells were inhibited. Nicotine was not directly involved in S. mutans LDH activity. However, since it increases the total number of bacterial cells in biofilm, the overall LDH activity of S. mutans biofilm is increased. In conclusion, nicotine stimulates S. mutans planktonic cell Gtf and Gbp expression. This leads to more planktonic cells attaching to the dental biofilm. Increased cell numbers within biofilm results in higher overall LDH activity. This contributes to caries development in smokers.

  13. Streptococcus pyogenes Arginine and Citrulline Catabolism Promotes Infection and Modulates Innate Immunity

    PubMed Central

    Cusumano, Zachary T.; Watson, Michael E.

    2014-01-01

    A bacterium's ability to acquire nutrients from its host during infection is an essential component of pathogenesis. For the Gram-positive pathogen Streptococcus pyogenes, catabolism of the amino acid arginine via the arginine deiminase (ADI) pathway supplements energy production and provides protection against acid stress in vitro. Its expression is enhanced in murine models of infection, suggesting an important role in vivo. To gain insight into the function of the ADI pathway in pathogenesis, the virulence of mutants defective in each of its enzymes was examined. Mutants unable to use arginine (ΔArcA) or citrulline (ΔArcB) were attenuated for carriage in a murine model of asymptomatic mucosal colonization. However, in a murine model of inflammatory infection of cutaneous tissue, the ΔArcA mutant was attenuated but the ΔArcB mutant was hyperattenuated, revealing an unexpected tissue-specific role for citrulline metabolism in pathogenesis. When mice defective for the arginine-dependent production of nitric oxide (iNOS−/−) were infected with the ΔArcA mutant, cutaneous virulence was rescued, demonstrating that the ability of S. pyogenes to utilize arginine was dispensable in the absence of nitric oxide-mediated innate immunity. This work demonstrates the importance of arginine and citrulline catabolism and suggests a novel mechanism of virulence by which S. pyogenes uses its metabolism to modulate innate immunity through depletion of an essential host nutrient. PMID:24144727

  14. Deciphering Key Residues Involved in the Virulence-promoting Interactions between Streptococcus pneumoniae and Human Plasminogen.

    PubMed

    Moreau, Christophe; Terrasse, Rémi; Thielens, Nicole M; Vernet, Thierry; Gaboriaud, Christine; Di Guilmi, Anne Marie

    2017-02-10

    Bacterial pathogens recruit circulating proteins to their own surfaces, co-opting the host protein functions as a mechanism of virulence. Particular attention has focused on the binding of plasminogen (Plg) to bacterial surfaces, as it has been shown that this interaction contributes to bacterial adhesion to host cells, invasion of host tissues, and evasion of the immune system. Several bacterial proteins are known to serve as receptors for Plg including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a cytoplasmic enzyme that appears on the cell surface in this moonlighting role. Although Plg typically binds to these receptors via several lysine-binding domains, the specific interactions that occur have not been documented in all cases. However, identification of the relevant residues could help define strategies for mitigating the virulence of important human pathogens, such as Streptococcus pneumoniae (Sp). To shed light on this question, we have described a combination of peptide-spot array screening, competition and SPR assays, high-resolution crystallography, and mutational analyses to characterize the interaction between SpGAPDH and Plg. We identified three SpGAPDH lysine residues that were instrumental in defining the kinetic and thermodynamic parameters of the interaction. Altogether, the integration of the data presented in this work allows us to propose a structural model for the molecular interaction of the SpGAPDH-Plg complex.

  15. Differences between Macrolide-Resistant and -Susceptible Streptococcus pyogenes: Importance of Clonal Properties in Addition to Antibiotic Consumption

    PubMed Central

    Silva-Costa, C.; Friães, A.; Melo-Cristino, J.

    2012-01-01

    A steady decline in macrolide resistance among Streptococcus pyogenes (group A streptococci [GAS]) in Portugal was reported during 1999 to 2006. This was accompanied by alterations in the prevalence of macrolide resistance phenotypes and in the clonal composition of the population. In order to test whether changes in the macrolide-resistant population reflected the same changing patterns of the overall population, we characterized both macrolide-susceptible and -resistant GAS associated with a diagnosis of tonsillo-pharyngitis recovered in the period from 2000 to 2005 in Portugal. Pulsed-field gel electrophoresis (PFGE) profiling was the best predictor of emm type and the only typing method that could discriminate clones associated with macrolide resistance and susceptibility within each emm type. Six PFGE clusters were significantly associated with macrolide susceptibility: T3-emm3-ST406, T4-emm4-ST39, T1-emm1-ST28, T6-emm6-ST382, B3264-emm89-ST101/ST408, and T2-emm2-ST55. Four PFGE clusters were associated with macrolide resistance: T4-emm4-ST39, T28-emm28-ST52, T12-emm22-ST46, and T1-emm1-ST28. We found no evidence for frequent ongoing horizontal transfer of macrolide resistance determinants. The diversity of the macrolide-resistant population was lower than that of susceptible isolates. The differences found between the two populations suggest that the macrolide-resistant population of GAS has its own dynamics, independent of the behavior of the susceptible population. PMID:22908153

  16. Emergence of macrolide resistance gene mph(B) in Streptococcus uberis and cooperative effects with rdmC-like gene.

    PubMed

    Achard, Adeline; Guérin-Faublée, Véronique; Pichereau, Vianney; Villers, Corinne; Leclercq, Roland

    2008-08-01

    Streptococcus uberis UCN60 was resistant to spiramycin (MIC = 8 microg/ml) but susceptible to erythromycin (MIC = 0.06 microg/ml), azithromycin (MIC = 0.12 microg/ml), josamycin (MIC = 0.25 microg/ml), and tylosin (MIC = 0.5 microg/ml). A 2.5-kb HindIII fragment was cloned from S. uberis UCN60 DNA on plasmid pUC18 and introduced into Escherichia coli AG100A, where it conferred resistance to spiramycin by inactivation. The sequence analysis of the fragment showed the presence of an rdmC-like gene that putatively encoded a protein belonging to the alpha/beta hydrolase family and of the first 196 nucleotides of the mph(B) gene putatively encoding a phosphotransferase known to inactivate 14-, 15-, and 16-membered macrolides in E. coli. The entire mph(B) gene was then identified in S. uberis UCN60. The two genes were expressed alone or in combination in E. coli, Staphylococcus aureus, and Enterococcus faecalis. Analysis of MICs revealed that rdmC-like alone did not confer resistance to erythromycin, tylosin, and josamycin in those three hosts. It conferred resistance to spiramycin in E. coli and E. faecalis but not in S. aureus. mph(B) conferred resistance in E. coli to erythromycin, tylosin, josamycin, and spiramycin but only low levels of resistance in E. faecalis and S. aureus to spiramycin (MIC = 8 microg/ml). The combination of mph(B) and rdmC-like genes resulted in a resistance to spiramycin and tylosin in the three hosts that significantly exceeded the mere addition of the resistance levels conferred by each resistance mechanism alone.

  17. The antimicrobial resistance patterns and associated determinants in Streptococcus suis isolated from humans in southern Vietnam, 1997-2008

    PubMed Central

    2011-01-01

    Background Streptococcus suis is an emerging zoonotic pathogen and is the leading cause of bacterial meningitis in adults in Vietnam. Systematic data on the antimicrobial susceptibility profiles of S. suis strains isolated from human cases are lacking. We studied antimicrobial resistance and associated resistance determinants in S. suis isolated from patients with meningitis in southern Vietnam. Methods S. suis strains isolated between 1997 and 2008 were investigated for their susceptibility to six antimicrobial agents. Strains were screened for the presence and expression of tetracycline and erythromycin resistance determinants and the association of tet(M) genes with Tn916- like transposons. The localization of tetracycline resistance gene tet(L) was determined by pulse field gel electrophoresis and Southern blotting. Results We observed a significant increase in resistance to tetracycline and chloramphenicol, which was concurrent with an increase in multi-drug resistance. In tetracycline resistance strains, we identified tet(M), tet(O), tet(W) and tet(L) and confirmed their expression. All tet(M) genes were associated with a Tn916-like transposon. The co-expression of tet(L) and other tetracycline resistance gene(s) encoding for ribosomal protection protein(s) was only detected in strains with a minimum inhibitory concentration (MIC) of tetracycline of ≥ 64 mg/L Conclusions We demonstrated that multi-drug resistance in S. suis causing disease in humans in southern Vietnam has increased over the 11-year period studied. We report the presence and expression of tet(L) in S. suis strains and our data suggest that co-expression of multiple genes encoding distinct mechanism is required for an MIC ≥ 64 mg/L to tetracycline. PMID:21208459

  18. Molecular Epidemiology of Macrolide-Resistant Isolates of Streptococcus pneumoniae Collected from Blood and Respiratory Specimens in Norway

    PubMed Central

    Littauer, P.; Sangvik, M.; Caugant, D. A.; Høiby, E. A.; Simonsen, G. S.; Sundsfjord, A.

    2005-01-01

    Norway has a low prevalence of antimicrobial resistance, including macrolide-resistant Streptococcus pneumoniae (MRSP). In a nationwide surveillance program, a total of 2,200 S. pneumoniae isolates were collected from blood cultures and respiratory tract specimens. Macrolide resistance was detected in 2.7%. M-type macrolide resistance was found in 60% of resistant isolates, and these were mainly mef(A)-positive, serotype-14 invasive isolates. The erm(B)-encoded macrolide-lincosamide-streptogramin B (MLSB) type dominated among the noninvasive isolates. One strain had an A2058G mutation in the 23S rRNA gene. Coresistance to other antibiotics was seen in 96% of the MLSB-type isolates, whereas 92% of the M-type isolates were susceptible to other commonly used antimicrobial agents. Serotypes 14, 6B, and 19F accounted for 84% of the macrolide-resistant isolates, with serotype 14 alone accounting for 67% of the invasive isolates. A total of 29 different sequence types (STs) were detected by multilocus sequence typing. Twelve STs were previously reported international resistant clones, and 75% of the macrolide-resistant isolates had STs identical or closely related to these clones. Eleven isolates displayed 10 novel STs, and 7/11 of these “Norwegian strains” coexpressed MLSB and tetracycline resistance, indicating the presence of Tn1545. The invasive serotype-14 isolates were all classified as ST9 or single-locus variants of this clone. ST9 is a mef-positive M-type clone, commonly known as England14-9, reported from several European countries. These observations suggest that the import of major international MRSP clones and the local spread of Tn1545 are the major mechanisms involved in the evolution and dissemination of MRSP in Norway. PMID:15872231

  19. Activities of Clinafloxacin, Gatifloxacin, Gemifloxacin, and Trovafloxacin against Recent Clinical Isolates of Levofloxacin-Resistant Streptococcus pneumoniae

    PubMed Central

    Jorgensen, J. H.; Weigel, L. M.; Swenson, J. M.; Whitney, C. G.; Ferraro, M. J.; Tenover, F. C.

    2000-01-01

    The activities of two investigational fluoroquinolones and three fluoroquinolones that are currently marketed were determined for 182 clinical isolates of Streptococcus pneumoniae. The collection included 57 pneumococcal isolates resistant to levofloxacin (MIC ≥ 8 μg/ml) recovered from patients in North America and Europe. All isolates were tested with clinafloxacin, gatifloxacin, gemifloxacin, levofloxacin, and trovafloxacin by the National Committee for Clinical Laboratory Standards broth microdilution and disk diffusion susceptibility test methods. Gemifloxacin demonstrated the greatest activity on a per gram basis, followed by clinafloxacin, trovafloxacin, gatifloxacin, and levofloxacin. Scatterplots of the MICs and disk diffusion zone sizes revealed a well-defined separation of levofloxacin-resistant and -susceptible strains when the isolates were tested against clinafloxacin and gatifloxacin. DNA sequence analyses of the quinolone resistance-determining regions of gyrA, gyrB, parC, and parE from 21 of the levofloxacin-resistant strains identified eight different patterns of amino acid changes. Mutations among the four loci had the least effect on the MICs of gemifloxacin and clinafloxacin, while the MICs of gatifloxacin and trovafloxacin increased by up to six doubling dilutions. These data indicate that the newer fluoroquinolones have greater activities than levofloxacin against pneumococci with mutations in the DNA gyrase or topoisomerase IV genes. Depending upon pharmacokinetics and safety, the greater potency of these agents could provide improved clinical efficacy against levofloxacin-resistant pneumococcal strains. PMID:11036007

  20. In Vitro Resistance Development to Nemonoxacin in Streptococcus pneumoniae: A Unique Profile for a Novel Nonfluorinated Quinolone.

    PubMed

    Roychoudhury, Siddhartha; Makin, Kelly; Twinem, Tracy; Leunk, Robert; Hsu, Ming Chu

    2016-10-01

    Selection of resistant strains in Streptococcus pneumoniae was studied in vitro with nemonoxacin, a novel nonfluorinated quinolone (NFQ), in comparison with quinolone benchmarks, ciprofloxacin, garenoxacin, and gatifloxacin. In stepwise resistance selection studies, a 256-fold loss of potency was observed after three to four steps of exposure to ciprofloxacin or garenoxacin. In contrast, the loss of potency was limited to eightfold after three steps of exposure to nemonoxacin and repeated attempts to isolate highly resistant organisms after four steps of exposure yielded isolates that could not be subcultured in liquid medium. The quinolone resistance-determining regions of the target genes, parC, parE, gyrA, and gyrB, were analyzed through DNA sequencing. Known mutations, especially in the hotspots of parC and gyrA, were selected with exposure to garenoxacin, ciprofloxacin, and gatifloxacin. In contrast, mutations selected with nemonoxacin were limited to GyrA, GyrB, and ParE, sparing ParC, which is known as a key driver of resistance in clinical isolates of S. pneumoniae. This observation is consistent with previous data using other NFQs, which showed no loss of potency due to ParC mutations in clinical isolates. This apparently unique feature of nemonoxacin is potentially attributable to the structural uniqueness of the NFQs, distinguishing them from the fluoroquinolones that are commonly prescribed for infections by S. pneumoniae.

  1. In Vitro Resistance Development to Nemonoxacin in Streptococcus pneumoniae: A Unique Profile for a Novel Nonfluorinated Quinolone

    PubMed Central

    Roychoudhury, Siddhartha; Makin, Kelly; Twinem, Tracy; Leunk, Robert

    2016-01-01

    Selection of resistant strains in Streptococcus pneumoniae was studied in vitro with nemonoxacin, a novel nonfluorinated quinolone (NFQ), in comparison with quinolone benchmarks, ciprofloxacin, garenoxacin, and gatifloxacin. In stepwise resistance selection studies, a 256-fold loss of potency was observed after three to four steps of exposure to ciprofloxacin or garenoxacin. In contrast, the loss of potency was limited to eightfold after three steps of exposure to nemonoxacin and repeated attempts to isolate highly resistant organisms after four steps of exposure yielded isolates that could not be subcultured in liquid medium. The quinolone resistance-determining regions of the target genes, parC, parE, gyrA, and gyrB, were analyzed through DNA sequencing. Known mutations, especially in the hotspots of parC and gyrA, were selected with exposure to garenoxacin, ciprofloxacin, and gatifloxacin. In contrast, mutations selected with nemonoxacin were limited to GyrA, GyrB, and ParE, sparing ParC, which is known as a key driver of resistance in clinical isolates of S. pneumoniae. This observation is consistent with previous data using other NFQs, which showed no loss of potency due to ParC mutations in clinical isolates. This apparently unique feature of nemonoxacin is potentially attributable to the structural uniqueness of the NFQs, distinguishing them from the fluoroquinolones that are commonly prescribed for infections by S. pneumoniae. PMID:27267788

  2. Effects of dietary levels of vitamin A on growth, hematology, immune response and resistance of Nile tilapia (Oreochromis niloticus) to Streptococcus iniae

    USDA-ARS?s Scientific Manuscript database

    This study was conducted to evaluate the effect of supplemental levels of vitamin A (0, 2,500, 5,000, 10,000, and 20,000 IU/kg diet) on the growth performance, hematology, immune response and resistance of Nile tilapia, Oreochromis niloticus to Streptococcus iniae challenge. Each diet was fed to Nil...

  3. Fitness cost, gyrB mutation, and absence of phosphotransferase system fructose specific IIABC component in novobiocin-resistant Streptococcus iniae vaccine strain ISNO

    USDA-ARS?s Scientific Manuscript database

    To understand the fitness cost of novobiocin-resistance in an attenuated Streptococcus iniae vaccine strain ISNO compared to its virulent parent strain ISET0901, cell proliferation rate of the two strains were compared to each other. Our results revealed that the cell proliferation rates of ISNO wer...

  4. High Prevalence of Macrolide-resistance and Molecular Characterization of Streptococcus pyogenes Isolates Circulating in China from 2009 to 2016.

    PubMed

    Lu, Binghuai; Fang, Yujie; Fan, Yanyan; Chen, Xingchun; Wang, Junrui; Zeng, Ji; Li, Yi; Zhang, Zhijun; Huang, Lei; Li, Hongxia; Li, Dong; Zhu, Fengxia; Cui, Yanchao; Wang, Duochun

    2017-01-01

    Streptococcus pyogenes, or group A Streptococcus, is a pathogen responsible for a wide range of clinical manifestations, from mild skin and soft tissue infections and pharyngitis to severe diseases. Its epidemiological characteristics should be comprehensively under surveillance for regulating the national prevention and treatment practice. Herein, a total of 140 S. pyogenes, including 38 invasive and 102 noninvasive isolates, were collected from infected patients in 10 tertiary general hospitals from 7 cities/provinces in China during the years 2009-2016. All strains were characterized by classical and molecular techniques for its emm types/subtypes, virulent factors and antibiotic resistance profiling. Of 140 isolates, 15 distinct emm types and 31 subtypes were detected, dominated by emm12 (60 isolates, 42.9%), emm1(43, 30.7%), and emm89 (10, 7.1%), and 8 new emm variant subtypes were identified. All strains, invasive or not, harbored the superantigenic genes, speB and slo. The other virulence genes, smeZ, speF, and speC accounted for 96.4, 91.4, and 87.1% of collected isolates, respectively. Further multilocus sequence typing (MLST) placed all strains into 22 individual sequence types (STs), including 4 newly-identified STs (11, 7.9%). All isolates were phenotypically susceptible to penicillin, ampicillin, cefotaxime, and vancomycin, whereas 131(93.5%), 132(94.2%), and 121(86.4%) were resistant to erythromycin, clindamycin, and tetracycline, respectively. Our study highlights high genotypic diversity and high prevalence of macrolide resistance of S. pyogenes among clinical isolates circulating in China.

  5. Increase in numbers of beta-lactam-resistant invasive Streptococcus pneumoniae in Brazil and the impact of conjugate vaccine coverage.

    PubMed

    Brandileone, Maria-Cristina C; Casagrande, Silvana Tadeu; Guerra, Maria-Luiza L S; Zanella, Rosemeire Cobo; Andrade, Ana-Lucia S S; Di Fabio, José-Luis

    2006-05-01

    A comprehensive investigation of invasive Streptococcus pneumoniae was carried out in Brazil as part of the programme of the national epidemiological surveillance system. The investigation provided data on the trends of resistance to antimicrobial agents. A total of 6470 isolates of S. pneumoniae collected in the country from 1993 to 2004 were tested. During this period of time, the number of penicillin-resistant strains rose from 10.2 to 27.9%. The proportions of intermediate and high-level resistant strains in 1993, which were 9.1 and 1.1%, respectively, rose to 22.0 and 5.9% in 2004. Geometric mean MICs for penicillin increased after the year 2000, to 0.19 microg ml(-1) in 2004; most of these isolates were from patients with pneumonia and from children under 5 years old, and belonged to serotype 14. There was a significant increase in the number of isolates belonging to serotypes included in the 7-valent conjugate vaccine from children under 5 years old: from 48.6% in 1993 to 69.6% in 2004, mainly related to an increase in the frequency of serotype 14 isolates. From 2000 to 2004, meningitis isolates showed higher resistance rates to cefotaxime (2.6%) compared to non-meningitis isolates (0.7%); percentages of isolates resistant to trimethoprim-sulfamethoxazole, tetracycline, erythromycin, chloramphenicol and rifampicin were 65, 14.6, 6.2, 1.3 and 0.7 %, respectively. No levoflaxin resistance was observed. Multidrug resistance was identified in 4.6% of isolates, of which 3.8% were resistant to three classes, 0.7% to four classes and 0.1% to five classes of antimicrobial agent. The study provides valuable information that may support empirical antimicrobial therapy for severe S. pneumoniae infections in Brazil, and emphasizes the need for conjugate pneumococcal vaccination.

  6. Antibiotic resistance in sputum isolates of Streptococcus pneumoniae in chronic obstructive pulmonary disease is related to antibiotic exposure.

    PubMed

    Desai, Himanshu; Richter, Sandra; Doern, Gary; Heilmann, Kris; Dohrn, Cassie; Johnson, Antoinette; Brauer, Aimee; Murphy, Timothy; Sethi, Sanjay

    2010-10-01

    Streptococcus pneumoniae (S. pneumoniae) is recovered from sputum of patients with chronic obstructive pulmonary disease (COPD) during stable disease and exacerbations. In patients with community acquired pneumonia, antibiotic exposure in the prior 3-6 months is associated with recovery of antibiotic resistant isolates of S. pneumoniae. Whether the same relationship is seen in COPD is not known. From April 1994 to June 2004, 127 adults with COPD were enrolled in a prospective longitudinal study. Sputum isolates of S. pneumoniae were characterized with susceptibility testing and pulsed-field gel electrophoresis (PFGE). The relationship between antibiotic use in the previous 3 and 6 months with either new acquisition of a resistant pneumococcal isolate or development of resistance (4-fold increase in MIC) in a pre-existing colonizing pneumococcal strain was determined. A total of 194 pneumococcal isolates were recovered from 38 patients. Among 71 newly acquired and 4 resistance-emergent strains analyzed further, rates of resistance to penicillin (MIC ≥2), erythromycin (MIC ≥1), tetracycline (MIC ≥8) and trimethoprim/sulfamethoxazole (MIC ≥4) were 8%, 24%, 17% and 16% respectively. Flouroquinolone resistance was not seen. Among strains isolated from patients exposed to a macrolide within 6 months, 53.6% displayed erythromycin resistance vs. 14% of strains without such exposure (p = 0.00085). Similar associations were not seen for other antibiotics. Macrolide use in the previous 6 months is associated with macrolide resistance in sputum isolates of S. pneumoniae. Recent antibiotic exposure may help in determining appropriate antibiotic treatment in these patients.

  7. New mutations and horizontal transfer of rpoB among rifampin-resistant Streptococcus pneumoniae from four Spanish hospitals.

    PubMed

    Ferrándiz, María José; Ardanuy, Carmen; Liñares, Josefina; García-Arenzana, José María; Cercenado, Emilia; Fleites, Ana; de la Campa, Adela G

    2005-06-01

    A total of 103 (0.7%) of 14,236 Streptococcus pneumoniae isolates collected in four Spanish hospitals from 1989 to 2003 were resistant to rifampin (MICs, 4 to 512 microg/ml). Only sixty-one (59.2%) of these isolates were available for molecular characterization. Resistance was mostly related to human immunodeficiency virus (HIV) infection in adult patients and to conjunctivitis in children. Thirty-six different pulsed-field gel electrophoresis patterns were identified among resistant isolates, five of which were related to international clones (Spain23F-1, Spain6B-2, Spain9V-3, Spain14-5, and clone C of serotype 19F), and accounted for 49.2% of resistant isolates. Single sense mutations at cluster N or I of the rpoB gene were found in 39 isolates, while double mutations, either at cluster I, at clusters I and II, or at clusters N and III, were found in 14 isolates. The involvement of the mutations in rifampin resistance was confirmed by genetic transformation. Single mutations at clusters N and I conferred MICs of 2 microg/ml and 4 to 32 microg/ml, respectively. Eight isolates showed high degrees of nucleotide sequence variations (2.3 to 10.8%) in rpoB, suggesting a recombinational origin for these isolates, for which viridans group streptococci are their potential gene donors. Although the majority of rifampin-resistant isolates were isolated from individual patients without temporal or geographical relationships, the clonal dissemination of rifampin-resistant isolates was observed among 12 HIV-infected patients in the two hospitals with higher rates of resistance.

  8. Neuraminidase A-Exposed Galactose Promotes Streptococcus pneumoniae Biofilm Formation during Colonization

    PubMed Central

    Blanchette, Krystle A.; Shenoy, Anukul T.; Milner, Jeffrey; Gilley, Ryan P.; McClure, Erin; Hinojosa, Cecilia A.; Kumar, Nikhil; Daugherty, Sean C.; Tallon, Luke J.; Ott, Sandra; King, Samantha J.; Ferreira, Daniela M.; Gordon, Stephen B.; Tettelin, Hervé

    2016-01-01

    Streptococcus pneumoniae is an opportunistic pathogen that colonizes the nasopharynx. Herein we show that carbon availability is distinct between the nasopharynx and bloodstream of adult humans: glucose is absent from the nasopharynx, whereas galactose is abundant. We demonstrate that pneumococcal neuraminidase A (NanA), which cleaves terminal sialic acid residues from host glycoproteins, exposed galactose on the surface of septal epithelial cells, thereby increasing its availability during colonization. We observed that S. pneumoniae mutants deficient in NanA and β-galactosidase A (BgaA) failed to form biofilms in vivo despite normal biofilm-forming abilities in vitro. Subsequently, we observed that glucose, sucrose, and fructose were inhibitory for biofilm formation, whereas galactose, lactose, and low concentrations of sialic acid were permissive. Together these findings suggested that the genes involved in biofilm formation were under some form of carbon catabolite repression (CCR), a regulatory network in which genes involved in the uptake and metabolism of less-preferred sugars are silenced during growth with preferred sugars. Supporting this notion, we observed that a mutant deficient in pyruvate oxidase, which converts pyruvate to acetyl-phosphate under non-CCR-inducing growth conditions, was unable to form biofilms. Subsequent comparative transcriptome sequencing (RNA-seq) analyses of planktonic and biofilm-grown pneumococci showed that metabolic pathways involving the conversion of pyruvate to acetyl-phosphate and subsequently leading to fatty acid biosynthesis were consistently upregulated during diverse biofilm growth conditions. We conclude that carbon availability in the nasopharynx impacts pneumococcal biofilm formation in vivo. Additionally, biofilm formation involves metabolic pathways not previously appreciated to play an important role. PMID:27481242

  9. The novel fibrinogen-binding protein FbsB promotes Streptococcus agalactiae invasion into epithelial cells.

    PubMed

    Gutekunst, Heike; Eikmanns, Bernhard J; Reinscheid, Dieter J

    2004-06-01

    Streptococcus agalactiae is a major cause of bacterial sepsis and meningitis in human newborns. The interaction of S. agalactiae with host proteins and the entry into host cells thereby represent important virulence traits of these bacteria. The present report describes the identification of the fbsB gene, encoding a novel fibrinogen-binding protein that plays a crucial role in the invasion of S. agalactiae into human cells. In Western blots and enzyme-linked immunosorbent assay (ELISA) experiments, the FbsB protein was demonstrated to interact with soluble and immobilized fibrinogen. Binding studies showed the N-terminal 388 residues of FbsB and the Aalpha-subunit of human fibrinogen to recognize each other. By reverse transcription (RT)-PCR, the fbsB gene was shown to be cotranscribed with the gbs0851 gene in S. agalactiae. Deletion of the fbsB gene in the genome of S. agalactiae did not influence the binding of the bacteria to fibrinogen, suggesting that FbsB does not participate in the attachment of S. agalactiae to fibrinogen. In tissue culture experiments, however, the fbsB deletion mutant was severely impaired in its invasion into lung epithelial cells. Bacterial invasion could be reestablished by introducing the fbsB gene on a shuttle plasmid into the fbsB deletion mutant. Furthermore, treatment of lung epithelial cells with FbsB fusion protein blocked S. agalactiae invasion of epithelial cells in a dose-dependent fashion. These results suggest an important role of the FbsB protein in the overall process of host cell entry by S. agalactiae.

  10. Neuraminidase A-Exposed Galactose Promotes Streptococcus pneumoniae Biofilm Formation during Colonization.

    PubMed

    Blanchette, Krystle A; Shenoy, Anukul T; Milner, Jeffrey; Gilley, Ryan P; McClure, Erin; Hinojosa, Cecilia A; Kumar, Nikhil; Daugherty, Sean C; Tallon, Luke J; Ott, Sandra; King, Samantha J; Ferreira, Daniela M; Gordon, Stephen B; Tettelin, Hervé; Orihuela, Carlos J

    2016-10-01

    Streptococcus pneumoniae is an opportunistic pathogen that colonizes the nasopharynx. Herein we show that carbon availability is distinct between the nasopharynx and bloodstream of adult humans: glucose is absent from the nasopharynx, whereas galactose is abundant. We demonstrate that pneumococcal neuraminidase A (NanA), which cleaves terminal sialic acid residues from host glycoproteins, exposed galactose on the surface of septal epithelial cells, thereby increasing its availability during colonization. We observed that S. pneumoniae mutants deficient in NanA and β-galactosidase A (BgaA) failed to form biofilms in vivo despite normal biofilm-forming abilities in vitro Subsequently, we observed that glucose, sucrose, and fructose were inhibitory for biofilm formation, whereas galactose, lactose, and low concentrations of sialic acid were permissive. Together these findings suggested that the genes involved in biofilm formation were under some form of carbon catabolite repression (CCR), a regulatory network in which genes involved in the uptake and metabolism of less-preferred sugars are silenced during growth with preferred sugars. Supporting this notion, we observed that a mutant deficient in pyruvate oxidase, which converts pyruvate to acetyl-phosphate under non-CCR-inducing growth conditions, was unable to form biofilms. Subsequent comparative transcriptome sequencing (RNA-seq) analyses of planktonic and biofilm-grown pneumococci showed that metabolic pathways involving the conversion of pyruvate to acetyl-phosphate and subsequently leading to fatty acid biosynthesis were consistently upregulated during diverse biofilm growth conditions. We conclude that carbon availability in the nasopharynx impacts pneumococcal biofilm formation in vivo Additionally, biofilm formation involves metabolic pathways not previously appreciated to play an important role. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  11. Novel proteinase inhibitor promotes resistance to insects

    USDA-ARS?s Scientific Manuscript database

    A novel Beta vulgaris serine proteinase inhibitor gene (BvSTI) and its protein are identified in response to insect feeding on B. vulgaris seedlings. BvSTI is cloned into an expression vector with constitutive promoter and transformed into Nicotiana benthamiana plants to assess BvSTI’s ability to ...

  12. Use of Antibiotics and Antimicrobial Resistance in Veterinary Medicine as Exemplified by the Swine Pathogen Streptococcus suis.

    PubMed

    Seitz, Maren; Valentin-Weigand, Peter; Willenborg, Jörg

    2016-01-01

    Use of antimicrobial agents in veterinary medicine is essential to control infectious diseases, thereby keeping animals healthy and animal products safe for the consumer. On the other hand, development and spread of antimicrobial resistance is of major concern for public health. Streptococcus (S.) suis reflects a typical bacterial pathogen in modern swine production due to its facultative pathogenic nature and wide spread in the pig population. Thus, in the present review we focus on certain current aspects and problems related to antimicrobial use and resistance in S. suis as a paradigm for a bacterial pathogen affecting swine husbandry worldwide. The review includes (i) general aspects of antimicrobial use and resistance in veterinary medicine with emphasis on swine, (ii) genetic resistance mechanisms of S. suis known to contribute to bacterial survival under antibiotic selection pressure, and (iii) possible other factors which may contribute to problems in antimicrobial therapy of S. suis infections, such as bacterial persister cell formation, biofilm production, and co-infections. The latter shows that we hardly understand the complexity of factors affecting the success of antimicrobial treatment of (porcine) infectious diseases and underlines the need for further research in this field.

  13. Rapid Determination of Macrolide and Lincosamide Resistance in Group B Streptococcus Isolated from Vaginal-Rectal Swabs

    PubMed Central

    Dela Cruz, Wilfred P.; Richardson, Joann Y.; Broestler, Judith M.; Thornton, Jennifer A.; Danaher, Patrick J.

    2007-01-01

    Objective. Our objective was to assess the ability of real-time PCR to predict in vitro resistance in isolates of group B streptococcus (GBS). Methods. The first real-time PCR assays for the genes known to confer resistance to erythromycin and clindamycin in GBS were developed. Three hundred and forty clinical GBS isolates were assessed with these assays and compared with conventional disk diffusion. Results. The presence of an erythromycin ribosome methylation gene (ermB or ermTR variant A) predicted in vitro constitutive or inducible resistance to clindamycin with a sensitivity of 93% (95% CI 86%–97%), specificity of 90% (95% CI 85%–93%), positive predictive value of 76% (95% CI 67%–84%), and negative predictive value of 97% (95% CI 94%–99%). Conclusion. This rapid and simple assay can predict in vitro susceptibility to clindamycin within two hours of isolation as opposed to 18–24 hours via disk diffusion. The assay might also be used to screen large numbers of batched isolates to establish the prevalence of resistance in a given area. PMID:17710240

  14. Comparative growth, cross stress resistance, transcriptomics of Streptococcus pyogenes cultured under low shear modeled microgravity and normal gravity

    PubMed Central

    Kalpana, Duraisamy; Im, Chanki; Lee, Yang Soo

    2015-01-01

    Streptococcus pyogenes is commonly found on pharynx, mouth and rarely on skin, lower gastrointestinal tract. It is a potential pathogen causing tonsillitis, pneumonia, endocarditis. The present study was undertaken to study the effects of low shear modeled microgravity on growth, morphology, antibiotic resistance, cross-stress resistance to various stresses and alteration in gene expression of S. pyogenes. The growth analysis performed using UV–Visible spectroscopy indicated decrease in growth of S. pyogenes under low shear modeled microgravity. Morphological analysis by Bio-transmission electron microscopy (TEM), Bio-scanning electron microscopy (SEM) did not reveal much difference between normal and low shear modeled microgravity grown S. pyogenes. The sensitivity of S. pyogenes to antibiotics ampicillin, penicillin, streptomycin, kanamycin, hygromycin, rifampicin indicates that the bacterium is resistant to hygromycin. Further S. pyogenes cultured under low shear modeled microgravity was found to be more sensitive to ampicillin and rifampicin as compared with normal gravity grown S. pyogenes. The bacteria were tested for the acid, osmotic, temperature and oxidative cross stress resistances. The gene expression of S. pyogenes under low shear modeled microgravity analyzed by microarray revealed upregulation of 26 genes and down regulation of 22 genes by a fold change of 1.5. PMID:26858535

  15. Comparative growth, cross stress resistance, transcriptomics of Streptococcus pyogenes cultured under low shear modeled microgravity and normal gravity.

    PubMed

    Kalpana, Duraisamy; Im, Chanki; Lee, Yang Soo

    2016-01-01

    Streptococcus pyogenes is commonly found on pharynx, mouth and rarely on skin, lower gastrointestinal tract. It is a potential pathogen causing tonsillitis, pneumonia, endocarditis. The present study was undertaken to study the effects of low shear modeled microgravity on growth, morphology, antibiotic resistance, cross-stress resistance to various stresses and alteration in gene expression of S. pyogenes. The growth analysis performed using UV-Visible spectroscopy indicated decrease in growth of S. pyogenes under low shear modeled microgravity. Morphological analysis by Bio-transmission electron microscopy (TEM), Bio-scanning electron microscopy (SEM) did not reveal much difference between normal and low shear modeled microgravity grown S. pyogenes. The sensitivity of S. pyogenes to antibiotics ampicillin, penicillin, streptomycin, kanamycin, hygromycin, rifampicin indicates that the bacterium is resistant to hygromycin. Further S. pyogenes cultured under low shear modeled microgravity was found to be more sensitive to ampicillin and rifampicin as compared with normal gravity grown S. pyogenes. The bacteria were tested for the acid, osmotic, temperature and oxidative cross stress resistances. The gene expression of S. pyogenes under low shear modeled microgravity analyzed by microarray revealed upregulation of 26 genes and down regulation of 22 genes by a fold change of 1.5.

  16. Correlation between genetic features of the mef(A)-msr(D) locus and erythromycin resistance in Streptococcus pyogenes.

    PubMed

    Vitali, Luca Agostino; Di Luca, Maria Chiara; Prenna, Manuela; Petrelli, Dezemona

    2016-01-01

    We investigated the correlation between the genetic variation within mef(A)-msr(D) determinants of efflux-mediated erythromycin resistance in Streptococcus pyogenes and the level of erythromycin resistance. Twenty-eight mef(A)-positive strains were selected according to erythromycin MIC (4-32 μg/mL), and their mef(A)-msr(D) regions were sequenced. Strains were classified according to the bacteriophage carrying mef(A)-msr(D). A new Φm46.1 genetic variant was found in 8 strains out of 28 and named VP_00501.1. Degree of allelic variation was higher in mef(A) than in msr(D). Hotspots for recombination were mapped within the locus that could have shaped the apparent mosaic structure of the region. There was a general correlation between mef(A)-msr(D) sequence and erythromycin resistance level. However, lysogenic conversion of susceptible strains by mef(A)-msr(D)-carrying Φm46.1 indicated that key determinants may not all reside within the mef(A)-msr(D) locus and that horizontal gene transfer could contribute to changes in the level of antibiotic resistance in S. pyogenes.

  17. Diversity of mosaic pbp2x families of penicillin-resistant Streptococcus pneumoniae from Iran and Romania.

    PubMed

    Mousavi, Seyed Fazlollah; Pana, Marina; Feizabadi, Mohammad; Jalali, Pantea; Ghita, Maria; Denapaite, Dalia; Hakenbeck, Regine

    2017-10-02

    High rates of penicillin-resistant Streptococcus pneumoniae occur in Romania and the Iran. The mosaic structure of PBP2x was investigated in nine Iranian strains and in 15 strains from Romania to understand their evolutionary history. Mutations potentially important for β-lactam resistance were identified by comparison with related PBP2x of penicillin-sensitive reference S. mitis strains. Two main PBP2x mosaic gene families were recognized. Eight Iranian strains belonged to group 1 PBP2x with a mosaic block highly related to PBP2x of the clone Spain(23F)-1 which is widespread among international penicillin-resistant S. pneumoniae clones. A second unique PBP2x group was observed in Romanian strains; furthermore, three PBP2x represented single mosaic variants. Sequence blocks of the penicillin-sensitive S. mitis 658 were common among PBP2x of strains from both countries. Each PBP2x group contained specific signature mutations within the transpeptidase domain, documenting distinct mutational pathways for the development of penicillin resistance. Copyright © 2017 Mousavi et al.

  18. Molecular epidemiology, antimicrobial susceptibilities and resistance mechanisms of Streptococcus pyogenes isolates resistant to erythromycin and tetracycline in Spain (1994–2006)

    PubMed Central

    2012-01-01

    Background Group A Streptococcus (GAS) causes human diseases ranging in severity from uncomplicated pharyngitis to life-threatening necrotizing fasciitis and shows high rates of macrolide resistance in several countries. Our goal is to identify antimicrobial resistance in Spanish GAS isolates collected between 1994 and 2006 and to determine the molecular epidemiology (emm/T typing and PFGE) and resistance mechanisms of those resistant to erythromycin and tetracycline. Results Two hundred ninety-five out of 898 isolates (32.8%) were erythromycin resistant, with the predominance of emm4T4, emm75T25, and emm28T28, accounting the 67.1% of the 21 emm/T types. Spread of emm4T4, emm75T25 and emm28T28 resistant clones caused high rates of macrolide resistance. The distribution of the phenotypes was M (76.9%), cMLSB (20.3%), iMLSB (2.7%) with the involvement of the erythromycin resistance genes mef(A) (89.5%), msr(D) (81.7%), erm(B) (37.3%) and erm(A) (35.9%). Sixty-one isolates were tetracycline resistant, with the main representation of the emm77T28 among 20 emm/T types. To note, the combination of tet(M) and tet(O) tetracycline resistance genes were similar to tet(M) alone reaching values close to 40%. Resistance to both antibiotics was detected in 19 isolates of 7 emm/T types, being emm11T11 and the cMLSB phenotype the most frequent ones. erm(B) and tet(M) were present in almost all the strains, while erm(A), mef(A), msr(D) and tet(O) appeared in less than half of them. Conclusions Spanish GAS were highly resistant to macrolides meanwhile showed minor resistance rate to tetracycline. A remarkable correlation between antimicrobial resistance and emm/T type was noticed. Clonal spread of emm4T4, emm75T25 and emm28T28 was the main responsable for macrolide resistance where as that emm77T28 clones were it to tetraclycline resistance. A wide variety of macrolide resistance genes were responsible for three macrolide resistance phenotypes. PMID:22998619

  19. Epidemiological study of erythromycin-resistant Streptococcus pyogenes from Korea and Japan by emm genotyping and multilocus sequence typing.

    PubMed

    Takahashi, Takashi; Arai, Kazuaki; Lee, Dong Hyun; Koh, Eun Ha; Yoshida, Haruno; Yano, Hisakazu; Kaku, Mitsuo; Kim, Sunjoo

    2016-01-01

    We determined the epidemiological characteristics of erythromycin (EM)-resistant Streptococcus pyogenes (group A streptococci, GAS) strains isolated from Korea and Japan, using emm genotyping and multilocus sequence typing (MLST). Clinical isolates of GAS had been collected from 1992 to 2012 in Korea and from 2004 to 2009 in Japan. EM resistance was determined by the microdilution method, and resistance genotypes were assessed by PCR. The emm genotyping and MLST were performed by DNA sequencing. The emm genotypes and sequence types (STs) were concordant in 143 (85.1%) of 168 EM-resistant GAS strains from Korea. ST36/emm12 (35.1%), ST52/emm28 (22.6%), and ST49/emm75 (16.1%) were the most common types. Most of the ST36 (93.9%) and ST52 (95.8%) strains harbored erm(B), whereas strains ST49, ST42, and ST15 contained mef(A). The concordance between emm genotypes and STs was 41 (93.2%) among 44 EM-resistant GAS strains from Japan. ST36/emm12 (34.1%), ST49/emm75 (18.2%), and ST28/emm1 (15.9%) were the major types. ST36 isolates harbored either erm(B) (56.3%) or mef(A) (37.5%), whereas isolates ST28, ST49, and ST38 carried only mef(A). The proportion of erm(B) and mef(A) was 66.1% and 33.3% in Korea and 22.7% and 68.2% in Japan, respectively. The common STs in Korea and Japan were ST36 and ST49, whereas ST52 was present only in Korea and ST28 only in Japan. Genotype erm(B) was predominant in Korea, whereas mef(A) was frequent in Japan. There were differences between Korea and Japan regarding the frequencies of emm genotypes, STs, and EM resistance genes among the EM-resistant GAS.

  20. [Study on the molecule epidemiological between resistances of 7 genes interrelated 4 antibiotic to isolated Streptococcus pneumoniae in children].

    PubMed

    Ding, Yun-fang; Mi, Zu-huang; Zhang, Jian-hua; Tao, Yun-zhen; Qin, Ling

    2005-06-01

    To investigate the molecule epidemic for 7 genes interrelated penicillin, erythromycin, tetracycline, vancomycin resistance of isolated Streptococcus pneumoniae (SP) in children at Suzhou area. (1) Thirty-one pneumococcal isolates were collected from respiratory tract secretions of children with respiratory diseases from Nov 2002 to Apr 2003 at the Children's Hospital of Suzhou University (reference strain ATCC49619). (2) Penicillin susceptibility was determined by E-test, while erythromycin, tetracycline, vancomycin were determined by K-B disk. (3) The detecting of pbp2B, ermA/B, mefA, tetM, vanA, vanB genes by PCR, Sequencing pbp2B genes, Contrasting pbp2B DNA sequences among pneumococcal isolates and SP R6 [penicillin sensitive (www.ncbi.nlm.gov/nucleotide, NC-003098)]. Of thirty-one isolates studied, the results were shown as follows; (1) Penicillin sensibility 38.7% (n = 12), penicillin resistance 61.3% (n = 19), pbp2B mutation 64.5% (n = 20); (2) Erythromycin sensibility 9.7% (n = 3), erythromycin resistance 90.3% (n = 28), ermA/B 71% (n = 22), mefA 32.1% (n = 10), ermA/B + mefA 87.1% (n = 27); (3) Tetracycline sensibility 9.7% (n = 3), tetracycline resistance 90.3% (n = 28), tetM 90.3% (n = 28); (4) Vancomycin sensibility 100% (n = 31), vanA, vanB all 0%. Among pneumococcal isolates at our area, penicillin, erythromycin, tetracycline resistance were high, vancomycin was sensitive. Detecting 7 genes interrelated penicillin, erythromycin, tetracycline, vancomycin resistance expressed genotypies for antibiotic resistances in pneumococcal isolates.

  1. The activity of 14-hydroxy clarithromycin, alone and in combination with clarithromycin, against penicillin- and erythromycin-resistant Streptococcus pneumoniae.

    PubMed

    Martin, S J; Garvin, C G; McBurney, C R; Sahloff, E G

    2001-05-01

    There are no data regarding the activity of clarithromycin's active metabolite, 14-hydroxy clarithromycin, against penicillin-intermediate, penicillin-resistant or erythromycin-resistant Streptococcus pneumoniae. Agar dilution MICs were determined for clarithromycin, 14-hydroxy clarithromycin (henceforth called 'metabolite'), azithromycin, erythromycin and clarithromycin/metabolite (2:1 and 1:1 ratio) against 24 penicillin-intermediate and 14 penicillin-resistant strains, including 13 erythromycin-resistant clinical strains and one ATCC strain of S. pneumoniae. The interaction between clarithromycin and its metabolite was determined using an agar chequerboard assay against all isolates, and time-kill tests were performed against five penicillin-intermediate (macrolide-susceptible) and five penicillin-resistant (two macrolide-resistant) strains of S. pneumoniae using all antibiotics alone at simulated peak serum concentrations, and clarithromycin/metabolite in a 2:1 ratio (physiological). MICs were as follows: clarithromycin, 0.008-->64 mg/L; metabolite, 0.015-->64 mg/L; erythromycin, 0.015-->64 mg/L; azithromycin, 0.125-->64 mg/L; clarithromycin/metabolite (1:1 and 2:1 combinations), 0.001-->64 mg/L. The MIC of the clarithromycin/metabolite combination was one or more tube dilution lower than the MIC of clarithromycin in 28 of the isolates tested. In chequerboard testing, 13 strains (seven erythromycin susceptible and six erythromycin resistant) demonstrated synergy, 18 additivity and seven indifference. In time-kill testing, bacterial eradication below detection limits occurred with clarithromycin and metabolite in seven of 10 organisms. The combination of parent and metabolite was more rapidly bactericidal than clarithromycin alone in six of the seven isolates (P = 0.026). The metabolite has potent activity against S. pneumoniae and enhances the activity of the parent compound against this organism. The metabolite's activity must be considered in evaluating

  2. SmaI macrorestriction analysis of Italian isolates of erythromycin-resistant Streptococcus pyogenes and correlations with macrolide-resistance phenotypes.

    PubMed

    Ripa, S; Zampaloni, C; Vitali, L A; Giovanetti, E; Montanari, M P; Prenna, M; Varaldo, P E

    2001-01-01

    High rates of erythromycin resistance among Streptococcus pyogenes strains have been reported in Italy in the last few years. In this study, 370 erythromycin-resistant (MIC, > or = 1 microg/mL) Italian isolates of this species obtained in 1997-1998 from throat swabs from symptomatic patients were typed by analyzing SmaI macrorestriction fragment patterns by pulsed-field gel electrophoresis (PFGE). Among the typable isolates (n = 341; the genomic DNA of the remaining 29 isolates was not restricted by SmaI), 48 distinct PFGE types were recognized, of which 31 were recorded in only one isolate (one-strain types). Fifty-two percent of typable isolates fell into three type clusters and 75% into six, suggesting that erythromycin-resistant group A streptococci circulating in Italy are polyclonal, but the majority of them probably derives from the spread of a limited number of clones. In parallel experiments, the 370 test strains were characterized for the macrolide resistance phenotype: 80 were assigned to phenotype cMLS, 89 to phenotype iMLS-A, 33 to phenotype iMLS-B, 11 to phenotype iMLS-C, and 157 to phenotype M. There was a close correlation between these phenotypic data and the genotypic results of PFGE analysis, the vast majority of the isolates assigned to individual PFGE classes belonging usually to a single phenotype of macrolide resistance. All of the 29 untypable isolates belonged to the M phenotype. Further correlations were observed with tetracycline resistance.

  3. Distribution of mef(A)-containing genetic elements in erythromycin-resistant isolates of Streptococcus pyogenes from Italy.

    PubMed

    D'Ercole, S; Petrelli, D; Prenna, M; Zampaloni, C; Catania, M R; Ripa, S; Vitali, L A

    2005-11-01

    In total, 124 Streptococcus pyogenes isolates were obtained from throat cultures of different symptomatic patients. All isolates showed M-phenotype macrolide resistance and contained the macrolide efflux gene mef(A). The isolates were screened for the presence and insertion site of mef(A)-containing genetic elements. In 25.8% of the isolates, mef(A) was found to be carried by elements belonging to the Tn1207.3/Phi10394.4 family inserted in the comEC gene, while 74.2% contained chimeric elements with a different genetic structure and chromosomal location, probably associated with the recently described 60-kb tet(O)-mef(A) element.

  4. Overexpression, purification, crystallization and preliminary X-ray diffraction of the nisin resistance protein from Streptococcus agalactiae.

    PubMed

    Khosa, Sakshi; Hoeppner, Astrid; Kleinschrodt, Diana; Smits, Sander H J

    2015-06-01

    Nisin is a 34-amino-acid antimicrobial peptide produced by Lactococcus lactis belonging to the class of lantibiotics. Nisin displays a high bactericidal activity against various Gram-positive bacteria, including some human-pathogenic strains. However, there are some nisin-non-producing strains that are naturally resistant owing to the presence of the nsr gene within their genome. The encoded protein, NSR, cleaves off the last six amino acids of nisin, thereby reducing its bactericidal efficacy. An expression and purification protocol has been established for the NSR protein from Streptococcus agalactiae COH1. The protein was successfully crystallized using the vapour-diffusion method in hanging and sitting drops, resulting in crystals that diffracted X-rays to 2.8 and 2.2 Å, respectively.

  5. Transcriptional attenuation controls macrolide inducible efflux and resistance in Streptococcus pneumoniae and in other Gram-positive bacteria containing mef/mel(msr(D)) elements.

    PubMed

    Chancey, Scott T; Bai, Xianhe; Kumar, Nikhil; Drabek, Elliott F; Daugherty, Sean C; Colon, Thomas; Ott, Sandra; Sengamalay, Naomi; Sadzewicz, Lisa; Tallon, Luke J; Fraser, Claire M; Tettelin, Hervé; Stephens, David S

    2015-01-01

    Macrolide resistance, emerging in Streptococcus pneumoniae and other Gram-positive bacteria, is increasingly due to efflux pumps encoded by mef/mel(msr) operons found on discrete mobile genetic elements. The regulation of mef/mel(msr) in these elements is not well understood. We identified the mef(E)/mel transcriptional start, localized the mef(E)/mel promoter, and demonstrated attenuation of transcription as a mechanism of regulation of macrolide-inducible mef-mediated macrolide resistance in S. pneumoniae. The mef(E)/mel transcriptional start site was a guanine 327 bp upstream of mef(E). Consensus pneumococcal promoter -10 (5'-TATACT-3') and -35 (5'-TTGAAC-3') boxes separated by 17 bp were identified 7 bp upstream of the start site. Analysis of the predicted secondary structure of the 327 5' region identified four pairs of inverted repeats R1-R8 predicted to fold into stem-loops, a small leader peptide [MTASMRLR, (Mef(E)L)] required for macrolide induction and a Rho-independent transcription terminator. RNA-seq analyses provided confirmation of transcriptional attenuation. In addition, expression of mef(E)L was also influenced by mef(E)L-dependent mRNA stability. The regulatory region 5' of mef(E) was highly conserved in other mef/mel(msr)-containing elements including Tn1207.1 and the 5612IQ complex in pneumococci and Tn1207.3 in Group A streptococci, indicating a regulatory mechanism common to a wide variety of Gram-positive bacteria containing mef/mel(msr) elements.

  6. Transcriptional Attenuation Controls Macrolide Inducible Efflux and Resistance in Streptococcus pneumoniae and in Other Gram-Positive Bacteria Containing mef/mel(msr(D)) Elements

    PubMed Central

    Chancey, Scott T.; Bai, Xianhe; Kumar, Nikhil; Drabek, Elliott F.; Daugherty, Sean C.; Colon, Thomas; Ott, Sandra; Sengamalay, Naomi; Sadzewicz, Lisa; Tallon, Luke J.; Fraser, Claire M.; Tettelin, Hervé; Stephens, David S.

    2015-01-01

    Macrolide resistance, emerging in Streptococcus pneumoniae and other Gram-positive bacteria, is increasingly due to efflux pumps encoded by mef/mel(msr) operons found on discrete mobile genetic elements. The regulation of mef/mel(msr) in these elements is not well understood. We identified the mef(E)/mel transcriptional start, localized the mef(E)/mel promoter, and demonstrated attenuation of transcription as a mechanism of regulation of macrolide-inducible mef-mediated macrolide resistance in S. pneumoniae. The mef(E)/mel transcriptional start site was a guanine 327 bp upstream of mef(E). Consensus pneumococcal promoter -10 (5′-TATACT-3′) and -35 (5′-TTGAAC-3′) boxes separated by 17 bp were identified 7 bp upstream of the start site. Analysis of the predicted secondary structure of the 327 5’ region identified four pairs of inverted repeats R1-R8 predicted to fold into stem-loops, a small leader peptide [MTASMRLR, (Mef(E)L)] required for macrolide induction and a Rho-independent transcription terminator. RNA-seq analyses provided confirmation of transcriptional attenuation. In addition, expression of mef(E)L was also influenced by mef(E)L-dependent mRNA stability. The regulatory region 5’ of mef(E) was highly conserved in other mef/mel(msr)-containing elements including Tn1207.1 and the 5612IQ complex in pneumococci and Tn1207.3 in Group A streptococci, indicating a regulatory mechanism common to a wide variety of Gram-positive bacteria containing mef/mel(msr) elements. PMID:25695510

  7. Pluronics-Formulated Farnesol Promotes Efficient Killing and Demonstrates Novel Interactions with Streptococcus mutans Biofilms

    PubMed Central

    Mogen, Austin B.; Chen, Fu; Ahn, Sang-Joon; Burne, Robert A.; Wang, Dong; Rice, Kelly C.

    2015-01-01

    Streptococcus mutans is the primary causative agent of dental caries, one of the most prevalent diseases in the United States. Previously published studies have shown that Pluronic-based tooth-binding micelles carrying hydrophobic antimicrobials are extremely effective at inhibiting S. mutans biofilm growth on hydroxyapatite (HA). Interestingly, these studies also demonstrated that non-binding micelles (NBM) carrying antimicrobial also had an inhibitory effect, leading to the hypothesis that the Pluronic micelles themselves may interact with the biofilm. To explore this potential interaction, three different S. mutans strains were each grown as biofilm in tissue culture plates, either untreated or supplemented with NBM alone (P85), NBM containing farnesol (P85F), or farnesol alone (F). In each tested S. mutans strain, biomass was significantly decreased (SNK test, p < 0.05) in the P85F and F biofilms relative to untreated biofilms. Furthermore, the P85F biofilms formed large towers containing dead cells that were not observed in the other treatment conditions. Tower formation appeared to be specific to formulated farnesol, as this phenomenon was not observed in S. mutans biofilms grown with NBM containing triclosan. Parallel CFU/ml determinations revealed that biofilm growth in the presence of P85F resulted in a 3-log reduction in viability, whereas F decreased viability by less than 1-log. Wild-type biofilms grown in the absence of sucrose or gtfBC mutant biofilms grown in the presence of sucrose did not form towers. However, increased cell killing with P85F was still observed, suggesting that cell killing is independent of tower formation. Finally, repeated treatment of pre-formed biofilms with P85F was able to elicit a 2-log reduction in viability, whereas parallel treatment with F alone only reduced viability by 0.5-log. Collectively, these results suggest that Pluronics-formulated farnesol induces alterations in biofilm architecture, presumably via interaction

  8. Pluronics-Formulated Farnesol Promotes Efficient Killing and Demonstrates Novel Interactions with Streptococcus mutans Biofilms.

    PubMed

    Mogen, Austin B; Chen, Fu; Ahn, Sang-Joon; Burne, Robert A; Wang, Dong; Rice, Kelly C

    2015-01-01

    Streptococcus mutans is the primary causative agent of dental caries, one of the most prevalent diseases in the United States. Previously published studies have shown that Pluronic-based tooth-binding micelles carrying hydrophobic antimicrobials are extremely effective at inhibiting S. mutans biofilm growth on hydroxyapatite (HA). Interestingly, these studies also demonstrated that non-binding micelles (NBM) carrying antimicrobial also had an inhibitory effect, leading to the hypothesis that the Pluronic micelles themselves may interact with the biofilm. To explore this potential interaction, three different S. mutans strains were each grown as biofilm in tissue culture plates, either untreated or supplemented with NBM alone (P85), NBM containing farnesol (P85F), or farnesol alone (F). In each tested S. mutans strain, biomass was significantly decreased (SNK test, p < 0.05) in the P85F and F biofilms relative to untreated biofilms. Furthermore, the P85F biofilms formed large towers containing dead cells that were not observed in the other treatment conditions. Tower formation appeared to be specific to formulated farnesol, as this phenomenon was not observed in S. mutans biofilms grown with NBM containing triclosan. Parallel CFU/ml determinations revealed that biofilm growth in the presence of P85F resulted in a 3-log reduction in viability, whereas F decreased viability by less than 1-log. Wild-type biofilms grown in the absence of sucrose or gtfBC mutant biofilms grown in the presence of sucrose did not form towers. However, increased cell killing with P85F was still observed, suggesting that cell killing is independent of tower formation. Finally, repeated treatment of pre-formed biofilms with P85F was able to elicit a 2-log reduction in viability, whereas parallel treatment with F alone only reduced viability by 0.5-log. Collectively, these results suggest that Pluronics-formulated farnesol induces alterations in biofilm architecture, presumably via interaction

  9. In vitro induction and selection of fluoroquinolone-resistant mutants of Streptococcus pyogenes strains with multiple emm types.

    PubMed

    Billal, Dewan S; Fedorko, Daniel P; Yan, S Steve; Hotomi, Muneki; Fujihara, Keiji; Nelson, Nancy; Yamanaka, Noboru

    2007-01-01

    To perform a systematic analysis of point mutations in the quinolone resistance determining regions (QRDRs) of the DNA gyrase and topoisomerase genes of emm type 6 and other emm types of Streptococcus pyogenes strains after in vitro exposure to stepwise increasing concentrations of levofloxacin. Twelve parent strains of S. pyogenes, each with a different emm type, were chosen for stepwise exposure to increasing levels of levofloxacin followed by selection of resistant mutants. The QRDRs of gyrA, gyrB, parC and parE correlating to mutants with increased MICs were analysed for point mutations. Multiple mutants with significantly increased MICs were generated from each strain. The amino acid substitutions identified were consistent regardless of emm type and were similar to the mechanisms of resistance reported in clinical isolates of S. pyogenes. The number of induction/selection cycles required for the emergence of key point mutations in gyrA and parC was variable among strains. For each parent-mutant set, when MIC increased, serine-81 of gyrA and serine-79 of parC were the primary targets for amino acid substitutions. No point mutations were found in the QRDRs of gyrB and parE in any of the resistant mutants sequenced. Despite its intrinsic polymorphism in the QRDR of parC, emm type 6 is not more likely to develop high-level resistance to fluoroquinolones when compared with other emm types. All emm types seem equally inducible to high-level fluoroquinolone resistance.

  10. Dominance of clonal complex 10 among the levofloxacin-resistant Streptococcus agalactiae isolated from bacteremic patients in a Korean hospital.

    PubMed

    Ryu, Hyejin; Park, Yeon-Joon; Kim, Yong-Kyun; Chang, Jiyoung; Yu, Jin Kyung

    2014-08-01

    Streptococcus agalactiae has emerged as an important cause of invasive infection in adults. Forty-nine S. agalactiae isolates (41 from adults and 8 from neonates) were collected during a 4-year period (2010-2013) and analyzed by multilocus sequence typing (MLST). Antibiotic susceptibility to erythromycin, clindamycin and levofloxacin was determined and the determinants of resistance (ermA, ermB, ermC, mefA, lnuB) were detected by PCR and mutation in gyrA, gyrB, parC and parE gene was investigated by sequence analysis. They were resolved into 14 sequence types (STs) and belonged to five clonal complexes (CCs). The distribution of CC was significantly different according to the age group; CC1 (18/41) and CC10 (13/41) was the most common among the adult isolates but CC19 (5/8) was predominant among the neonatal isolates. The resistance rate to erythromycin, clindamycin was 18.4% and 24.5%, respectively. Among the 13 strains resistant to erythromycin and/or clindamycin, two isolates harbored ermA and 10 isolates harbored ermB. The levofloxacin resistance rate was very high (32.7%) and was significantly higher in CC10 (71.4%). All the levofloxacin-resistant isolates had identical gyrA substitution (Ser81Leu) but parC substitution was different according to the CCs. The additional mutation in parE (His221Tyr) was found only in CC19. Continuous monitoring of the fluoroquinolone resistance and genotypic distribution among S. agalactiae is needed. Copyright © 2014. Published by Elsevier Ltd.

  11. β-lactam Resistance, Serotype Distribution, and Genotypes of Meningitis-causing Streptococcus pneumoniae, Rio de Janeiro, Brazil

    PubMed Central

    Barroso, David E.; Godoy, Daniel; Castiñeiras, Terezinha M. P. P.; Tulenko, Mary M.; Rebelo, Maria C.; Harrison, Lee H.

    2016-01-01

    Background Here, we report a laboratory-based study of Streptococcus pneumoniae recovered from patients with meningitis in Rio de Janeiro State, Brazil. Methods The aim of this study was to determine the evolution of β-lactam resistance, antimicrobial susceptibility pattern, serotypes, and genetic diversity of S. pneumoniae, isolated from meningitis patients between 2000 and 2008. Results A total of 264 S. pneumoniae recovered from patients between 2000 and 2008 were included. Susceptibility testing (E-test) of S. pneumoniae showed resistance to penicillin, ceftriaxone, oxacillin, cotrimoxazole, tetracycline, ofloxacin, erythromycin, chloramphenicol, and rifampicin. Penicillin resistance (PEN-R, minimal inhibitory concentration [MIC] ≥0.12 μg/mL) increased from 8% of isolates in 2000–2002, to 12% in 2003–2005, and to 20% in 2006–2008. Ceftriaxone resistance (MIC ≥1.0 μg/mL) was detected among some PEN-R isolates (13%) from 2004 onward. Within the PEN-R isolates, serotypes that are included in 10-valent pneumococcal conjugate vaccine predominated (90%), and resistance was detected mostly in isolates of serotypes 14 (61%), 23F (16%), 6B (10%), and 19F (3%). Multilocus sequence typing showed that 52% of the PEN-R isolates, and 89% of those with MICs ≥0.5 μg/mL, were sequence type (ST)-156 or single-locus variants of this ST (ST-557 or ST-4388); all of these isolates were serotype 14 and were assigned to the Spain9V-3 clone. Conclusions β-lactam resistance increased recently among cerebrospinal fluid isolates and was mainly due to the surge of the ST-4388, a previously undescribed gki single-locus variants of ST-156. Regional surveillance is shown to be essential to provide optimal antimicrobial therapy, monitor highly successful clones, and formulate adequate vaccination strategy. PMID:21860337

  12. Genetic Diversity of the tet(M) Gene in Tetracycline-Resistant Clonal Lineages of Streptococcus pneumoniae

    PubMed Central

    Doherty, Neil; Trzcinski, Krzysztof; Pickerill, Paul; Zawadzki, Piotr; Dowson, Christopher G.

    2000-01-01

    The aim of the present study was to examine the stability and evolution of tet(M)-mediated resistance to tetracyclines among members of different clonal lineages of Streptococcus pneumoniae. Thirty-two tetracycline-resistant isolates representing three national (Spanish serotype 14, Spanish serotype 15, and Polish serotype 23F) and one international (Spanish serotype 23F) multidrug-resistant epidemic clones were all found to be tet(M) positive and tet(O), tet(K), and tet(L) negative. These isolates all carried the integrase gene, int, which is associated with the Tn1545-Tn916 family of conjugative transposons. High-resolution restriction analysis of tet(M) products identified six alleles, tet(M)1 to tet(M)6: tet(M)1 to tet(M)3 and tet(M)5 in isolates of the Spanish serotype 14 clone, tet(M)4 in both the Spanish serotype 15 and 23F clones, and tet(M)6, the most divergent allele, in the Polish 23F clone. This indicates that tet(M) variation can occur at the inter- and intraclone levels in pneumococci. Two alleles of int were identified, with int1 being found in all isolates apart from members of the international Spanish 23F clone, which carried int2. Susceptibility to tetracycline, doxycycline, and minocycline was evaluated for all isolates with or without preincubation in the presence of subinhibitory concentrations of tetracyclines. Resistance to tetracyclines was found to be inducible in isolates of all clones; however, the strongest induction was observed in the Spanish serotype 15 and 23F clones carrying tet(M)4. Tetracycline was found to be the strongest inducer of resistance, and minocycline was found to be the weakest inducer of resistance. PMID:11036009

  13. Garenoxacin activity against isolates form patients hospitalized with community-acquired pneumonia and multidrug-resistant Streptococcus pneumoniae.

    PubMed

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

    2007-05-01

    Community-acquired pneumonia (CAP) continues to cause significant morbidity worldwide, and the principal bacterial pathogens (Streptococcus pneumoniae and Haemophilus influenzae) have acquired numerous resistance mechanisms over the last few decades. CAP treatment guidelines have suggested the use of broader spectrum agents, such as antipneumococcal fluoroquinolones as the therapy for at-risk patient population. In this report, we studied 3087 CAP isolates from the SENTRY Antimicrobial Surveillance Program (1999-2005) worldwide and all respiratory tract infection (RTI) isolate population of pneumococci (14665 strains) grouped by antibiogram patterns against a new des-F(6)-quinolone, garenoxacin. Results indicated that garenoxacin was highly active against CAP isolates of S. pneumoniae (MIC(90), 0.06 microg/mL) and H. influenzae (MIC(90), < or =0.03 microg/mL). This garenoxacin potency was 8- to 32-fold greater than gatifloxacin, levofloxacin, and ciprofloxacin against the pneumococci and >99.9% of strains were inhibited at < or =1 microg/mL (proposed susceptible breakpoint). Garenoxacin MIC values were not affected by resistances among S. pneumoniae strains to penicillin or erythromycin; however, coresistances were high among the beta-lactams (penicillins and cephalosporins), macrolides, tetracyclines, and trimethoprim/sulfamethoxazole. Analysis of S. pneumoniae isolates with various antimicrobial resistance patterns to 6 drug classes demonstrated that garenoxacin was active against >99.9% (MIC, < or =1 microg/mL) of strains, and the most resistant pneumococci (6-drug resistance, 1051 strains or 7.2% of all isolates) were completely susceptible (100.0% at < or =1 microg/mL) to garenoxacin (MIC(90), 0.06 microg/mL). These results illustrate the high activity of garenoxacin against contemporary CAP isolates and especially against multidrug-resistant (MDR) S. pneumoniae that have created therapeutic dilemmas for all RTI presentations. Garenoxacin appears to be a

  14. Promoting Improved Ballistic Resistance of Transparent Armor

    SciTech Connect

    Wereszczak, Andrew A; Patel, P; Templeton, D W

    2011-01-01

    Transparent armor is a material or system of materials designed to be optically transparent, yet protect from fragmentation or ballistic impacts. Although engineered to defeat specific threats, or a range of threats, there are general requirements common to all of these designs. The primary requirement for a transparent armor system is to not only defeat the designated threat but also provide a multi-hit capability with minimized distortion of surrounding areas. Ground platforms have several parameters that must be optimized, such as weight, space efficiency, and cost versus performance. Glass exhibits tensile failure stress that is very much dependent on the amount of material being stressed, the side being tensile-stressed (i.e., air-versus tin-side if a float glass), and where it is being tensile stressed (i.e., in the middle or near an edge). An axiom arising from those effects is a greater amount of allowable deflection (i.e., higher failure stress) of a ballistically impacted transparent armor will result in improved ballistic resistance. Therefore, the interpretation and management of those tensile-failure-stress dependencies shall ultimately improve ballistic resistance and its predictability of transparent armor. Each of those three dependencies (size, side, and location) in a soda-lime silicate glass is described.

  15. Evolution and Diversity of the Antimicrobial Resistance Associated Mobilome in Streptococcus suis: A Probable Mobile Genetic Elements Reservoir for Other Streptococci.

    PubMed

    Huang, Jinhu; Ma, Jiale; Shang, Kexin; Hu, Xiao; Liang, Yuan; Li, Daiwei; Wu, Zuowei; Dai, Lei; Chen, Li; Wang, Liping

    2016-01-01

    Streptococcus suis is a previously neglected, newly emerging multidrug-resistant zoonotic pathogen. Mobile genetic elements (MGEs) play a key role in intra- and interspecies horizontal transfer of antimicrobial resistance (AMR) determinants. Although, previous studies showed the presence of several MGEs, a comprehensive analysis of AMR-associated mobilome as well as their interaction and evolution has not been performed. In this study, we presented the AMR-associated mobilome and their insertion hotspots in S. suis. Integrative conjugative elements (ICEs), prophages and tandem MGEs were located at different insertion sites, while 86% of the AMR-associated MGEs were inserted at rplL and rum loci. Comprehensive analysis of insertions at rplL and rum loci among four pathogenic Streptococcus species (Streptococcus agalactiae, Streptococcus pneumoniae, Streptococcus pyogenes, and S. suis) revealed the existence of different groups of MGEs, including Tn5252, ICESp1108, and TnGBS2 groups ICEs, Φm46.1 group prophage, ICE_ICE and ICE_prophage tandem MGEs. Comparative ICE genomics of ICESa2603 family revealed that module exchange and acquisition/deletion were the main mechanisms in MGEs' expansion and evolution. Furthermore, the observation of tandem MGEs reflected a novel mechanism for MGE diversity. Moreover, an in vitro competition assay showed no visible fitness cost was observed between different MGE-carrying isolates and a conjugation assay revealed the transferability of ICESa2603 family of ICEs. Our statistics further indicated that the prevalence and diversity of MGEs in S. suis is much greater than in other three species which prompted our hypothesis that S. suis is probably a MGEs reservoir for other streptococci. In conclusion, our results showed that acquisition of MGEs confers S. suis not only its capability as a multidrug resistance pathogen, but also represents a paradigm to study the modular evolution and matryoshkas of MGEs.

  16. High prevalence of Streptococcus agalactiae from vaginas of women in Taiwan and its mechanisms of macrolide and quinolone resistance.

    PubMed

    Lee, Wen-Tsung; Lai, Mei-Chin

    2015-10-01

    Streptococcus agalactiae (GBS), is the most common pathogen causing infections among perinatal women and neonatal babies. Nonetheless, there are few studies on the occurrence of GBS among the pregnant women and the mechanisms of GBS resistance to quinolones and macrolides in Taiwan. GBS were isolated from vaginas of the pregnant and non-pregnant symptomatic women in Taiwan. The prevalence, antimicrobial susceptibility, and mechanisms of resistance against erythromycin and quinolone of total 188 isolates were studied. The isolation rate of GBS from pregnant women was significantly higher at 21.8% compare with the non-pregnant women of 13.2%. Antibiotic susceptibility test of the 188 GBS isolates revealed a high non-susceptible rate for erythromycin (50.0%) while the rate for levofloxacin was only 4.8%. Among 94 erythromycin non-susceptible GBS isolates, ermB gene was detected 83.1% (59/71) for those GBS that were non-susceptible to both clindamycin and tetracycline, which was significantly higher than GBS that are susceptible to clindamycin but resistant to tetracycline at 43.8% (7/16). No ermA or mef gene was detected in any isolate. Mutations were detected in the parC and gyrA genes in 14 out of 18 levofloxacin non-susceptible isolates. The predominant mutation type was the combination of Ser79Tyr in parC and Ser81Leu mutations in gyrA. GBS is the most common isolated pathogens in vaginal infections in Taiwan, resistance to tetracycline and erythromycin is higher than the rate observed for other regions of the world, while the resistance rate for levofloxacin was relatively lower in Taiwan. Copyright © 2014. Published by Elsevier B.V.

  17. Comparative Genome Analysis of the Daptomycin-Resistant Streptococcus anginosus Strain J4206 Associated with Breakthrough Bacteremia

    PubMed Central

    Rahman, Maliha; Nguyen, Scott V.; McCullor, Kimberly A.; King, Catherine J.; Jorgensen, James H.; McShan, W. Michael

    2016-01-01

    Streptococcus anginosus is a member of the normal oral flora that can become a pathogen causing pyogenic infections in humans. The genome of daptomycin-resistant strain J4206, originally isolated from a patient suffering from breakthrough bacteremia and septic shock at the University of Texas Health Science Center at San Antonio, was determined. The circular genome is 2,001,352 bp long with a GC content of 38.62% and contains multiple mobile genetic elements, including the phage-like chromosomal island SanCI that mediates a mutator phenotype, transposons, and integrative conjugative elements. Daptomycin resistance involves multiple alterations in the cell membrane and cell wall, and unique features were identified in J4206 that may contribute to resistance. A cluster of capsular polysaccharide (CPS) genes for choline metabolism and transport are present that may help neutralize cell surface charges, destabilizing daptomycin binding. Further, unique J4206 genes encoding sortases and LPXTG-target proteins that are involved in cell wall modification were present. The J4206 genome is phylogenetically closely related to the recently reported vancomycin-resistant SA1 strain; however, these genomes differ with SNPs in cardiolipin synthetase, histidine kinase yycG, teichoic acid modification genes, and other genes involved in cell surface modification. Transmission electron microscopy showed that the cell walls of both strains J4206 and SA1 were significantly thicker and more electron dense than daptomycin- and vancomycin-sensitive strain J4211. This comparative genomic study has identified unique genes as well as allelic variants in the J4206 genome that are involved in cell surface modification and thus might contribute to the acquisition of daptomycin resistance. PMID:27678123

  18. Association between fluoroquinolone usage and a dramatic rise in ciprofloxacin-resistant Streptococcus pneumoniae in Canada, 1997-2006.

    PubMed

    Adam, Heather J; Hoban, Daryl J; Gin, Alfred S; Zhanel, George G

    2009-07-01

    This study evaluated the prevalence of fluoroquinolone usage and investigated the association between usage and resistance in respiratory isolates of Streptococcus pneumoniae in Canada. Fluoroquinolone susceptibility testing was conducted on S. pneumoniae collected from 25 medical centres across Canada over nine study years. Fluoroquinolone prescriptions and consumption figures were derived from data in the IMS Health, Canada CompuScript Audit. Between 1997 and 2006, 11825 S. pneumoniae isolates were collected. Ciprofloxacin resistance rates increased significantly (P<0.01) during the study from 0% to 4.5% in children (0-15 years), from 0.2% to 5.4% in adults (16-64 years) and from 1.4% to 11.6% in the elderly (> or = 65 years). Outpatient ciprofloxacin and respiratory fluoroquinolone prescriptions increased by 55.6% (38.2 prescriptions/1000 population to 59.4 prescriptions/1000 population; P<0.01) and 416.2% (5.3 prescriptions/1000 to 27.4 prescriptions/1000; P<0.01), respectively. Ciprofloxacin and respiratory fluoroquinolone consumption increased by 10.6% [1.1 defined daily doses (DDDs)/1000/day to 1.2 DDDs/1000/day; P=0.02] and 38.2% (0.5 to 0.7 DDDs/1000/day; P=0.02), respectively, from 2001 to 2006. A strong association between ciprofloxacin use and resistance (R(2)=0.89) was identified. Fluoroquinolone resistance in S. pneumoniae increased significantly in Canada from 1997 to 2006 in conjunction with increased ciprofloxacin and respiratory fluoroquinolone consumption. Ciprofloxacin usage appears to be the biggest driver of resistance; however, total fluoroquinolone usage is also important.

  19. [In vitro resistance rates of Streptococcus pneumoniae and Haemophilus influenzae clinical isolates to the antibiotics used in therapy].

    PubMed

    Uncu, Hikmet; Colakoğlu, Sule; Turunç, Tuba; Demiroğlu, Yusuf Ziya; Arslan, Hande

    2007-07-01

    Streptococcus pneumoniae and Haemophilus influenzae which cause infections with high morbidity and mortality all over the world, are also the most important bacterial pathogens of community-acquired pneumoniae. In recent years S. pneumoniae is becoming increasingly resistant to a variety of antibiotics. The aim of this study was to detect the in vitro resistance rates of S. pneumoniae and H. influenzae strains isolated from different clinical samples to the antibiotics which are used in the therapy of infections due to these pathogens. Between the period of January 2005 to May 2006, 77 S. pneumoniae (44 sputum, 20 blood, 8 bronchoalveolar lavage, 4 pleural fluids and 1 tracheal aspirate isolate) and 31 H. influenzae (30 sputum and 1 bronchoalveolar lavage isolate) strains isolated from patients who were admitted to Baskent University Hospital, Research and Practice Center of Adana (located in southern Turkey), were included to the study. The antibiotic susceptibility tests were performed by disc diffusion method according to CLSI (Clinical and Laboratory Standards Institute; M100-S13) guidelines. The MIC values of S. pneumoniae which gave an inhibition zone diameter of > or =19 mm in with disc diffusion test, were detected by E-test (AB Biodisk, Sweden). Intermediate and high resistance rates of pneumococci to penicilin were found as 38.9% (30/77) and 10.4% (8/77), respectively, with a total resistance rate of 49.4%. Trimethoprim-sulphamethoxazole (TMP/SMX), erithromycin, tetracyclin, clindamycin and chloramphenicol were the other antibiotics which followed penicillin with the resistance rates of 42.8%, 37.6%, 31.1%, 23.3% and 10.3%, respectively. Amongst H. influenzae strains, one (3.2%) was found to be a beta-lactamase producer and it was resistant to both ampicillin and azitromycin. Eight (25.8%) of H. influenzae isolates were resistant to TMP/SMX, and two (6.4%) were resistant to chloramphenicol. As a result, the high penicilin and erithromycin resistance rates

  20. Tau deletion promotes brain insulin resistance

    PubMed Central

    Marciniak, Elodie; Leboucher, Antoine; Caron, Emilie; Ahmed, Tariq; Tailleux, Anne; Dumont, Julie; Issad, Tarik; Gerhardt, Ellen; Pagesy, Patrick; Vileno, Margaux; Hamdane, Malika; Bantubungi, Kadiombo; Lancel, Steve; Demeyer, Dominique; Eddarkaoui, Sabiha; Vallez, Emmanuelle; Vieau, Didier; Humez, Sandrine; Faivre, Emilie; Grenier-Boley, Benjamin; Outeiro, Tiago F.; Amouyel, Philippe; Balschun, Detlef

    2017-01-01

    The molecular pathways underlying tau pathology–induced synaptic/cognitive deficits and neurodegeneration are poorly understood. One prevalent hypothesis is that hyperphosphorylation, misfolding, and fibrillization of tau impair synaptic plasticity and cause degeneration. However, tau pathology may also result in the loss of specific physiological tau functions, which are largely unknown but could contribute to neuronal dysfunction. In the present study, we uncovered a novel function of tau in its ability to regulate brain insulin signaling. We found that tau deletion leads to an impaired hippocampal response to insulin, caused by altered IRS-1 and PTEN (phosphatase and tensin homologue on chromosome 10) activities. Our data also demonstrate that tau knockout mice exhibit an impaired hypothalamic anorexigenic effect of insulin that is associated with energy metabolism alterations. Consistently, we found that tau haplotypes are associated with glycemic traits in humans. The present data have far-reaching clinical implications and raise the hypothesis that pathophysiological tau loss-of-function favors brain insulin resistance, which is instrumental for cognitive and metabolic impairments in Alzheimer’s disease patients. PMID:28652303

  1. Trends in Antimicrobial Resistance in 1,968 Invasive Streptococcus pneumoniae Strains Isolated in Spanish Hospitals (2001 to 2003): Decreasing Penicillin Resistance in Children's Isolates

    PubMed Central

    Oteo, Jesús; Lázaro, Edurne; de Abajo, Francisco J.; Baquero, Fernando; Campos, José

    2004-01-01

    To address the public health problem of antibiotic resistance, the European Union (EU) founded the European Antimicrobial Resistance Surveillance System. A network of 40 hospitals that serve approximately 30% of the Spanish population (about 12 million) participated. Each laboratory reported data on antimicrobial susceptibility testing using standard laboratory procedures that were evaluated by an external quality control program. The antibiotic consumption data were obtained from the National Health System. We compared the antibiotic susceptibility of Spanish isolates of invasive Streptococcus pneumoniae (2001 to 2003) with antibiotic consumption. Invasive S. pneumoniae was isolated from 1,968 patients, 20% of whom were children at or below the age of 14 years. Of non-penicillin-susceptible strains (35.6%; 95% confidence interval, 34 to 37.2), 26.4% were considered intermediate and 9.2% were considered resistant. Between 2001 and 2003, penicillin resistance decreased from 39.5 to 33% overall and from 60.4 to 41.2% in children at or below the age of 14 years (P = 0.002). Resistance to erythromycin was at 26.6%, and coresistance with penicillin was at 19.1%. Of total isolates, the ciprofloxacin MIC was >2 μg/ml for 2.1%, with numbers increasing from 0.4% (2001) to 3.9% (2003). Total antibiotic use decreased from 21.66 to 19.71 defined daily doses/1,000 inhabitants/day between 1998 and 2002. While consumption of broad-spectrum penicillins, cephalosporins, and erythromycin declined, use of amoxicillin-clavulanate and quinolones increased by 17.5 and 27%, respectively. The frequency of antibiotic resistance in invasive S. pneumoniae in Spain was among the highest in the EU. However, a significant decrease in penicillin resistance was observed in children. This decrease coincided with the introduction of a heptavalent conjugate pneumoccocal vaccine (June 2001) and with a global reduction in antibiotic consumption levels. PMID:15583283

  2. Changing Trends in Antimicrobial Resistance and Serotypes of Streptococcus pneumoniae Isolates in Asian Countries: an Asian Network for Surveillance of Resistant Pathogens (ANSORP) Study

    PubMed Central

    Kim, So Hyun; Chung, Doo Ryeon; Thamlikitkul, Visanu; Yang, Yonghong; Wang, Hui; Lu, Min; So, Thomas Man-kit; Hsueh, Po-Ren; Yasin, Rohani M.; Carlos, Celia C.; Pham, Hung Van; Lalitha, M. K.; Shimono, Nobuyuki; Perera, Jennifer; Shibl, Atef M.; Baek, Jin Yang; Kang, Cheol-In; Ko, Kwan Soo; Peck, Kyong Ran

    2012-01-01

    Antimicrobial resistance in Streptococcus pneumoniae remains a serious concern worldwide, particularly in Asian countries, despite the introduction of heptavalent pneumococcal conjugate vaccine (PCV7). The Asian Network for Surveillance of Resistant Pathogens (ANSORP) performed a prospective surveillance study of 2,184 S. pneumoniae isolates collected from patients with pneumococcal infections from 60 hospitals in 11 Asian countries from 2008 to 2009. Among nonmeningeal isolates, the prevalence rate of penicillin-nonsusceptible pneumococci (MIC, ≥4 μg/ml) was 4.6% and penicillin resistance (MIC, ≥8 μg/ml) was extremely rare (0.7%). Resistance to erythromycin was very prevalent in the region (72.7%); the highest rates were in China (96.4%), Taiwan (84.9%), and Vietnam (80.7%). Multidrug resistance (MDR) was observed in 59.3% of isolates from Asian countries. Major serotypes were 19F (23.5%), 23F (10.0%), 19A (8.2%), 14 (7.3%), and 6B (7.3%). Overall, 52.5% of isolates showed PCV7 serotypes, ranging from 16.1% in Philippines to 75.1% in Vietnam. Serotypes 19A (8.2%), 3 (6.2%), and 6A (4.2%) were the most prominent non-PCV7 serotypes in the Asian region. Among isolates with serotype 19A, 86.0% and 79.8% showed erythromycin resistance and MDR, respectively. The most remarkable findings about the epidemiology of S. pneumoniae in Asian countries after the introduction of PCV7 were the high prevalence of macrolide resistance and MDR and distinctive increases in serotype 19A. PMID:22232285

  3. [Resistance to macrolides in the species Streptococcus pyogenes in the Czech Republic in 1996-2003].

    PubMed

    Urbásková, P; Jakubů, V

    2004-11-01

    The study of the prevalence of erythromycin resistance in 22 169 S. pyogenes strains in the Czech Republic in 1996-2003 on the background of rough data on the nationwide consumption of macrolide antibiotics confirmed that the exponential growth of resistance observed in 1998-2001 copied with a delay the rise in macrolide antibiotic consumption recorded in 1992-1995. The highest frequency of erythromycin resistance was found in 2001 (16.5%) with a subsequent decrease to 14.5% in 2002 and to 9.1% in 2003. The drop in resistance followed the stagnation in macrolide consumption and its decrease by 17% in 2002. Upward and downward trends in macrolide resistance in different regions and age groups copied the nationwide trends with some quantitative differences that could not be analyzed in view of the lack of detailed data on antibiotic consumption. A 99.5% concordance was found between the results of the phenotypic method and those of detection of genes coding for constitutive, inducible and efflux resistance to macrolide-lincosamide-streptograminB (MLSB) antibiotics. In 2001 when the highest erythromycin resistance was recorded in the Czech Republic, most of the tested strains (91.2%) showed resistance to all MLSB antibiotics, with macrolide efflux (susceptibility to lincosamides and 16-membered macrolides was conserved) being implicated in resistance of 8.8% of the strains only. In 2003, the number of erythromycin resistant strains decreased and the resistance mechanism was ascribed to macrolide efflux in 26.8% of them. Almost all of the strains with constitutive or induced MLSB resistance are also resistant to either tetracycline or bacitracin or both. In the light of S. pyogenes resistance to bacitracin, the bacitracin disk is not usable in preliminary identification any more.

  4. The Streptococcus pneumoniae pezAT Toxin–Antitoxin System Reduces β-Lactam Resistance and Genetic Competence

    PubMed Central

    Chan, Wai T.; Espinosa, Manuel

    2016-01-01

    Chromosomally encoded Type II Toxin–Antitoxin operons are ubiquitous in bacteria and archaea. Antitoxins neutralize the toxic effect of cognate Toxins by protein–protein interactions and sequestering the active residues of the Toxin. Toxins target essential bacterial processes, mostly translation and replication. However, one class apart is constituted by the PezAT pair because the PezT toxin target cell wall biosynthesis. Here, we have examined the role of the pezAT toxin–antitoxin genes in its natural host, the pathogenic bacterium Streptococcus pneumoniae. The pezAT operon on Pneumococcal Pathogenicity Island 1 was deleted from strain R6 and its phenotypic traits were compared with those of the wild type. The mutant cells formed shorter chains during exponential phase, leading to increased colony-forming units. At stationary phase, the mutant was more resilient to lysis. Importantly, the mutant exhibited higher resistance to antibiotics targeting cell walls (β-lactams), but not to antibiotics acting at other levels. In addition, the mutants also showed enhanced genetic competence. We suggest that PezAT participates in a subtle equilibrium between loss of functions (resistance to β-lactams and genetic competence) and gain of other traits (virulence). PMID:27610103

  5. Relative potential for selection of quinolone-resistance-determining-region mutations in Streptococcus pneumoniae by gemifloxacin, gatifloxacin and moxifloxacin.

    PubMed

    De Azavedo, J C S; Duncan, C L; Kilburn, L; Downar, J; Kong, B; Lad, S; Low, D E; Bast, D J

    2006-08-01

    Serial passage of a clinical isolate of Streptococcus pneumoniae, in the presence of moxifloxacin, gatifloxacin or gemifloxacin, gave rise to resistant isolates. Non-susceptibility as defined by Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) breakpoints arose on Days 10, 11, and 12 with gatifloxacin, gemifloxacin, and moxifloxacin respectively. Moxifloxacin and gatifloxacin selected for a single step quinolone-resistant-determining-region (QRDR) mutation in DNA gyrase (GyrA) on Day 4 and 7 respectively, whereas gemifloxacin selected simultaneously for multi-step mutations in gyrase and topoisomerase IV (ParC) on Day 17 and activated a non-reserpine inhibited efflux mechanism by Day 4. As found in clinical isolates, mutations included Ser-81-Phe and Glu-85-Lys in GyrA and Ser-79-Phe or Asp-83-Tyr in ParC. At high MICs, moxifloxacin showed a previously unreported 4 amino-acid deletion in GyrB as well as a more unusual substitution Ser-79-Leu/Ile in ParC. Gemifloxacin showed a 2- to 16-fold greater activity than moxifloxacin or gatifloxacin against strains with two or more QRDR mutations, however, its potency did not translate to nonsusceptibility and gemifloxacin MIC values were either at or well above the CLSI nonsusceptible breakpoint concentration.

  6. Horizontal Transfer of parC and gyrA in Fluoroquinolone-Resistant Clinical Isolates of Streptococcus pneumoniae

    PubMed Central

    Ferrándiz, María José; Fenoll, Asunción; Liñares, Josefina; De La Campa, Adela G.

    2000-01-01

    We have analyzed genetically three clinical isolates (3180, 3870, and 1244) of Streptococcus pneumoniae with high-level ciprofloxacin resistance. Isolates 3180 and 3870 were atypical because of their insolubility in deoxycholate. However, they hybridized specifically with pneumococcal autolysin and pneumolysin gene probes and have typical pneumococcal atpC and atpA gene sequences. Analysis of the complete sequences of the parC and gyrA genes revealed total variations of 8 and 8.7% (isolate 3180) and 7.4 and 3.6% (isolate 3870), respectively, compared to the wild-type strain R6 sequence. The variations observed between the sequences of R6 and isolate 1244 were less than 0.9%. The structure of the gyrA and parC genes from isolates 3180 and 3870 was organized in sequence blocks that show different levels of divergence, suggesting a pattern of recombination. These results are evidence for recombination at the fluoroquinolone target genes in clinical isolates of S. pneumoniae. The genetically related viridans group streptococci could act as a reservoir for fluoroquinolone resistance genes. PMID:10722479

  7. Pharmacodynamic assessment based on mutant prevention concentrations of fluoroquinolones to prevent the emergence of resistant mutants of Streptococcus pneumoniae.

    PubMed

    Homma, Tomoyuki; Hori, Toshihiko; Sugimori, Giichi; Yamano, Yoshinori

    2007-11-01

    The objective of this study was to investigate the relationship between pharmacokinetic and pharmacodynamic parameters, on the basis of the mutant prevention concentration (MPC) concept, and the emergence of resistant mutants of Streptococcus pneumoniae to fluoroquinolone antibacterials. Some clinical isolates with various MIC and MPC values of moxifloxacin and levofloxacin were exposed under conditions simulating the time-concentration curves observed when moxifloxacin (400 or 80 mg, once a day) or levofloxacin (200 mg, twice a day) was orally administered by using an in vitro pharmacodynamic model. The decrease in susceptibility was evaluated by altering the population analysis profiles after moxifloxacin or levofloxacin treatment for 72 h. When the area under the concentration-time curve from 0 to 24 h (AUC(0-24))/MPC and peak concentration (C(max))/MPC were above 13.41 and 1.20, respectively, complete eradication occurred and no decrease in susceptibility was observed. On the other hand, when AUC(0-24)/MPC and C(max)/MPC were below 0.84 and 0.08, respectively, the susceptibility decreased. However, the time inside the mutant selective window and the time above the MPC did not show any correlation with the decrease in susceptibility. These results suggest that AUC(0-24)/MPC and C(max)/MPC are important parameters for predicting the emergence of resistant mutants and that higher values indicate greater effectiveness.

  8. Horizontal transfer of parC and gyrA in fluoroquinolone-resistant clinical isolates of Streptococcus pneumoniae.

    PubMed

    Ferrándiz, M J; Fenoll, A; Liñares, J; De La Campa, A G

    2000-04-01

    We have analyzed genetically three clinical isolates (3180, 3870, and 1244) of Streptococcus pneumoniae with high-level ciprofloxacin resistance. Isolates 3180 and 3870 were atypical because of their insolubility in deoxycholate. However, they hybridized specifically with pneumococcal autolysin and pneumolysin gene probes and have typical pneumococcal atpC and atpA gene sequences. Analysis of the complete sequences of the parC and gyrA genes revealed total variations of 8 and 8.7% (isolate 3180) and 7.4 and 3.6% (isolate 3870), respectively, compared to the wild-type strain R6 sequence. The variations observed between the sequences of R6 and isolate 1244 were less than 0.9%. The structure of the gyrA and parC genes from isolates 3180 and 3870 was organized in sequence blocks that show different levels of divergence, suggesting a pattern of recombination. These results are evidence for recombination at the fluoroquinolone target genes in clinical isolates of S. pneumoniae. The genetically related viridans group streptococci could act as a reservoir for fluoroquinolone resistance genes.

  9. Genetic diversity of Streptococcus suis isolated from three pig farms of China obtained by acquiring antibiotic resistance genes.

    PubMed

    Huang, Jinhu; Shang, Kexin; Kashif, Jam; Wang, Liping

    2015-05-01

    Acquiring antibiotic resistance genes may change an organism's genetic characteristics and the effect of antibiotics, resulting in a rapid transmission of microbial pathogens. The objectives of this experiment were to identify the features of Streptococcus suis (S. suis) isolated from three pig farms in China which are geographically isolated. Among the isolates, 56.52% were sequence type 7 (ST7), followed by ST1 (26.09%), indicating that ST7 prevails in China, as revealed by multi-locus sequence typing (MLST). Statistical analysis indicated an association between geography, sequence types and antibiotic resistance genotypes. 66.67% of the isolates in Sichuan province presented a (ermB(-) + mefA(-) + tetO(-) + tetM(-)) + ST7 type. The tetM(+) +ST7 type was the most prevalent in Jiangsu province, whereas the strains from Hebei province had a phenotype ermB(+) +tetO(+) +ST1 (63.64%). Pulsed-field gel electrophoresis (PGFE) pattern A2 with 100% similarity reflected the clonal dissemination between Sichuan and Jiangsu provinces. Strains carrying or not carrying antibiotic resistance genes presented different PFGE patterns in Hebei province. ST7 is widespread in many regions of China and a clonal dissemination occurred between Sichuan and Jiangsu provinces in diseased pigs. However, ST1 strains with macrolide and tetracycline resistance (ermB(+) +tetO(+) +ST1) isolated from a farm in Hebei province demonstrated that the genetic diversity was contributed by horizontal acquiring of ermB and tetO carrying elements. © 2014 Society of Chemical Industry.

  10. Synergistic stimulation of type I interferons during influenza virus coinfection promotes Streptococcus pneumoniae colonization in mice.

    PubMed

    Nakamura, Shigeki; Davis, Kimberly M; Weiser, Jeffrey N

    2011-09-01

    Pneumococcal infection of the respiratory tract is often secondary to recent influenza virus infection and accounts for much of the morbidity and mortality during seasonal and pandemic influenza. Here, we show that coinfection of the upper respiratory tract of mice with influenza virus and pneumococcus leads to synergistic stimulation of type I IFNs and that this impairs the recruitment of macrophages, which are required for pneumococcal clearance, due to decreased production of the chemokine CCL2. Type I IFN expression was induced by pneumococcal colonization alone. Colonization followed by influenza coinfection led to a synergistic type I IFN response, resulting in increased density of colonizing bacteria and susceptibility to invasive infection. This enhanced type I IFN response inhibited production of the chemokine CCL2, which promotes the recruitment of macrophages and bacterial clearance. Stimulation of CCL2 by macrophages upon pneumococcal infection alone required the pattern recognition receptor Nod2 and expression of the pore-forming toxin pneumolysin. Indeed, the increased colonization associated with concurrent influenza virus infection was not observed in mice lacking Nod2 or the type I IFN receptor, or in mice challenged with pneumococci lacking pneumolysin. We therefore propose that the synergistic stimulation of type I IFN production during concurrent influenza virus and pneumococcal infection leads to increased bacterial colonization and suggest that this may contribute to the higher rates of disease associated with coinfection in humans.

  11. Group A Streptococcus intranasal infection promotes CNS infiltration by streptococcal-specific Th17 cells

    PubMed Central

    Dileepan, Thamotharampillai; Smith, Erica D.; Knowland, Daniel; Hsu, Martin; Platt, Maryann; Bittner-Eddy, Peter; Cohen, Brenda; Southern, Peter; Latimer, Elizabeth; Harley, Earl; Agalliu, Dritan; Cleary, P. Patrick

    2015-01-01

    Group A streptococcal (GAS) infection induces the production of Abs that cross-react with host neuronal proteins, and these anti-GAS mimetic Abs are associated with autoimmune diseases of the CNS. However, the mechanisms that allow these Abs to cross the blood-brain barrier (BBB) and induce neuropathology remain unresolved. We have previously shown that GAS infection in mouse models induces a robust Th17 response in nasal-associated lymphoid tissue (NALT). Here, we identified GAS-specific Th17 cells in tonsils of humans naturally exposed to GAS, prompting us to explore whether GAS-specific CD4+ T cells home to mouse brains following i.n. infection. Intranasal challenge of repeatedly GAS-inoculated mice promoted migration of GAS-specific Th17 cells from NALT into the brain, BBB breakdown, serum IgG deposition, microglial activation, and loss of excitatory synaptic proteins under conditions in which no viable bacteria were detected in CNS tissue. CD4+ T cells were predominantly located in the olfactory bulb (OB) and in other brain regions that receive direct input from the OB. Together, these findings provide insight into the immunopathology of neuropsychiatric complications that are associated with GAS infections and suggest that crosstalk between the CNS and cellular immunity may be a general mechanism by which infectious agents exacerbate symptoms associated with other CNS autoimmune disorders. PMID:26657857

  12. Natural Variation in the Promoter of the Gene Encoding the Mga Regulator Alters Host-Pathogen Interactions in Group A Streptococcus Carrier Strains

    PubMed Central

    Flores, Anthony R.; Olsen, Randall J.; Wunsche, Andrea; Kumaraswami, Muthiah; Shelburne, Samuel A.; Carroll, Ronan K.

    2013-01-01

    Humans commonly carry pathogenic bacteria asymptomatically, but the molecular factors underlying microbial asymptomatic carriage are poorly understood. We previously reported that two epidemiologically unassociated serotype M3 group A Streptococcus (GAS) carrier strains had an identical 12-bp deletion in the promoter of the gene encoding Mga, a global positive gene regulator. Herein, we report on studies designed to test the hypothesis that the identified 12-bp deletion in the mga promoter alters GAS virulence, thereby potentially contributing to the asymptomatic carrier phenotype. Using allelic exchange, we introduced the variant promoter into a serotype M3 invasive strain and the wild-type promoter into an asymptomatic carrier strain. Compared to strains with the wild-type mga promoter, we discovered that strains containing the promoter with the 12-bp deletion produced significantly fewer mga and Mga-regulated gene transcripts. Consistent with decreased mga transcripts, strains containing the variant mga promoter were also significantly less virulent in in vivo and ex vivo models of GAS disease. Further, we provide evidence that the pleiotropic regulator protein CodY binds to the mga promoter and that the 12-bp deletion in the mga promoter reduces CodY-mediated mga transcription. We conclude that the naturally occurring 12-bp deletion in the mga promoter significantly alters the pathogen-host interaction of these asymptomatic carrier strains. Our findings provide new insight into the molecular basis of the carrier state of an important human pathogen. PMID:23980109

  13. Genetic and phenotypic characterization of resistance to macrolides in Streptococcus pyogenes from Argentina.

    PubMed

    Martínez, Silvia; Amoroso, Ana M; Famiglietti, Angela; de Mier, Carmen; Vay, Carlos; Gutkind, Gabriel O

    2004-01-01

    Five hundred and seventy-eight strains of group A streptococci (GAS) isolated mostly from paediatric pharyngeal swabs were tested to evaluate their susceptibility to erythromycin. Resistant strains were then tested for their MICs to erythromycin and clindamycin, their phenotype of resistance to macrolides-lincosamides-streptogramin (MLS(B)) and for the presence of macrolide resistance genes. The rate of resistance to erythromycin was 8.2%. Constitutive, inducible and M phenotypes of resistance were detected in 2.1, 2.1 and 95.8% of resistant strains, respectively. All M phenotypes harboured the mefA gene, whereas constitutive and inducible phenotypes had ermB and ermTR genes, respectively.

  14. Streptococcus iniae and Streptococcus agalactiae

    USDA-ARS?s Scientific Manuscript database

    Streptococcus iniae and S. agalactiae are economically important Gram positive bacterial pathogens of cultured and wild fish with a worldwide distribution. Both bacteria are potential zoonotic pathogens and have been associated most often with infections in immunocompromised people. Streptococcus in...

  15. [MALDI-ToF mass-spectrometry in analysis of genetically determined resistance of Streptococcus pneumoniae to fluoroquinolones].

    PubMed

    Malakhova, M V; Vereshchagin, V A; Il'ina, E N; Govorun, V M; Filimonova, O Iu; Grudinina, S A; Sidorenko, S V

    2007-01-01

    New fluoroquinolones with higher antipneumococcal activity are considered promising in the treatment of respiratory tract infections. Still, their wide use in clinical practice is connected with possible selection and rapid distribution of the resistance, requiring constant monitoring. Development of resistance to fluoroquinolones results from step-wise accumulation of mutations in the genes of DNA-gyrase and topoisomerase IV, the mutations of the first step being not always accompanied by a significant increase of the MIC of the new fluoroquinolones. Therefore, to detect the first signs of the resistance development, it is necessary not only to detect the susceptibility of the circulating Streptococcus pneumoniae strains phenotypically, but also to detect the genetic changes. In the present study the minisequent reaction followed by detection of the reaction products by MALD-ToF mass-spectrometry was used to reveal the mutations in the genes of the fluoroquinolone targets of 38 S. pneumoniae strains with different levels of the resistance to ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin. In the strains with high resistance to all the three fluoroquinolones (MIC 4-16 mcg/ml) there were detected mutations in GyrA (Ser81Tyr or Glu85Zys) and as well in ParC (Ser79Phe or Ser79Tyr). In the strains resistant to ofloxacin and ciprofloxacin (MIC 4-8 mcg/ml) with preserved susceptibility to levofloxacin and moxifloxacin, the mutations were detected only in GyrA (Ser114Gly). In the moderately resistant strains (MICs 4 and 2-4 mcg/ml respectively for ofloxacin and ciprofloxacin) there were detected the known mutations in ParC (Ser79Tyr or Ser79Phe or Asp83Tyr) and in GyrB (Glu475Lys) as well as the earlier not described mutations in ParE (ins Asn381a) and in Gyr B (Thr329Ala or Va1355Ile). The described method can be used in mass screening of S. pneumoniae strains for the presence of mutations in the genes of the fluoroquinolone targets.

  16. Effect of new breakpoints proposed by Clinical and Laboratory Standards Institute in 2008 for evaluating penicillin resistance of Streptococcus pneumoniae in a Turkish University Hospital.

    PubMed

    Doğan, Ozlem; Gülmez, Dolunay; Hasçelik, Gülşen

    2010-03-01

    Clinical and Laboratory Standards Institute changed penicillin susceptibility breakpoints for Streptococcus pneumoniae in 2008. After reevaluation with new breakpoints, resistance rates decreased from 6.1% to 0.5% for nonmeningitis and increased from 6.6% to 33.3% for meningitis isolates in our hospital. This breakpoint modification is expected to reduce the inconsistency between susceptibility results and therapeutic outcomes; however, both the clinical microbiology laboratories and the clinicians should be aware of the change to interpret the susceptibility results.

  17. Complete Genome Sequences of Three Multidrug-Resistant Clinical Isolates of Streptococcus pneumoniae Serotype 19A with Different Susceptibilities to the Myxobacterial Metabolite Carolacton

    PubMed Central

    Bunk, Boyke; Schober, Isabel; Spröer, Cathrin; Bergmann, Simone; Jarek, Michael; Overmann, Jörg; Wagner-Döbler, Irene

    2017-01-01

    ABSTRACT The full-genome sequences of three drug- and multidrug-resistant Streptococcus pneumoniae clinical isolates of serotype 19A were determined by PacBio single-molecule real-time sequencing, in combination with Illumina MiSeq sequencing. A comparison to the genomes of other pneumococci indicates a high nucleotide sequence identity to strains Hungary19A-6 and TCH8431/19A. PMID:28209832

  18. Complete Genome Sequence of emm28 Type Streptococcus pyogenes MEW123, a Streptomycin-Resistant Derivative of a Clinical Throat Isolate Suitable for Investigation of Pathogenesis

    PubMed Central

    Jacob, Kristin M.; Spilker, Theodore; LiPuma, John J.; Dawid, Suzanne R.

    2016-01-01

    We present here the complete genome sequence of Streptococcus pyogenes type emm28 strain MEW123, a streptomycin-resistant derivative of a pediatric throat isolate. The genome length is 1,878,699 bp, with 38.29% G+C% content. The genome sequence adds value to this virulent emm28 representative strain and will aid in the investigation of streptococcal pathogenesis. PMID:26988051

  19. Involvement of the Putative ATP-Dependent Efflux Proteins PatA and PatB in Fluoroquinolone Resistance of a Multidrug-Resistant Mutant of Streptococcus pneumoniae

    PubMed Central

    Marrer, Estelle; Schad, Karen; Satoh, Andreas T.; Page, Malcolm G. P.; Johnson, Maggie M.; Piddock, Laura J. V.

    2006-01-01

    The multidrug-resistant mutant Streptococcus pneumoniae M22 constitutively overexpresses two genes (patA and patB) that encode proteins homologous to known efflux proteins belonging to the ABC transporter family. It is shown here that PatA and PatB were strongly induced by quinolone antibiotics and distamycin in fluoroquinolone-sensitive strains. PatA was very important for growth of S. pneumoniae, and it could not be disrupted in strain M22. PatB appeared to control metabolic activity, particularly in amino acid biosynthesis, and it may have a pivotal role in coordination of the response to quinolone antibiotics. The induction of PatA and PatB by antibiotics showed a pattern similar to that exhibited by SP1861, a homologue of ABC-type transporters of choline and other osmoprotectants. A second group of quinolone-induced transporter genes comprising SP1587 and SP0287, which are homologues of, respectively, oxalate/formate antiporters and xanthine or uracil permeases belonging to the major facilitator family, showed a different pattern of induction by other antibiotics. There was no evidence for the involvement of PmrA, the putative proton-dependent multidrug transporter that has been implicated in norfloxacin resistance, in the response to quinolone antibiotics in either the resistant mutant or the fluoroquinolone-sensitive strains. PMID:16436727

  20. Salivaricin D, a novel intrinsically trypsin-resistant lantibiotic from Streptococcus salivarius 5M6c isolated from a healthy infant.

    PubMed

    Birri, Dagim Jirata; Brede, Dag Anders; Nes, Ingolf F

    2012-01-01

    In this work, we purified and characterized a newly identified lantibiotic (salivaricin D) from Streptococcus salivarius 5M6c. Salivaricin D is a 34-amino-acid-residue peptide (3,467.55 Da); the locus of the gene encoding this peptide is a 16.5-kb DNA segment which contains genes encoding the precursor of two lantibiotics, two modification enzymes (dehydratase and cyclase), an ABC transporter, a serine-like protease, immunity proteins (lipoprotein and ABC transporters), a response regulator, and a sensor histidine kinase. The immunity gene (salI) was heterologously expressed in a sensitive indicator and provided significant protection against salivaricin D, confirming its immunity function. Salivaricin D is a naturally trypsin-resistant lantibiotic that is similar to nisin-like lantibiotics. It is a relatively broad-spectrum bacteriocin that inhibits members of many genera of Gram-positive bacteria, including the important human pathogens Streptococcus pyogenes and Streptococcus pneumoniae. Thus, Streptococcus salivarius 5M6c may be a potential biological agent for the control of oronasopharynx-colonizing streptococcal pathogens or may be used as a probiotic bacterium.

  1. Salivaricin D, a Novel Intrinsically Trypsin-Resistant Lantibiotic from Streptococcus salivarius 5M6c Isolated from a Healthy Infant

    PubMed Central

    Birri, Dagim Jirata; Brede, Dag Anders

    2012-01-01

    In this work, we purified and characterized a newly identified lantibiotic (salivaricin D) from Streptococcus salivarius 5M6c. Salivaricin D is a 34-amino-acid-residue peptide (3,467.55 Da); the locus of the gene encoding this peptide is a 16.5-kb DNA segment which contains genes encoding the precursor of two lantibiotics, two modification enzymes (dehydratase and cyclase), an ABC transporter, a serine-like protease, immunity proteins (lipoprotein and ABC transporters), a response regulator, and a sensor histidine kinase. The immunity gene (salI) was heterologously expressed in a sensitive indicator and provided significant protection against salivaricin D, confirming its immunity function. Salivaricin D is a naturally trypsin-resistant lantibiotic that is similar to nisin-like lantibiotics. It is a relatively broad-spectrum bacteriocin that inhibits members of many genera of Gram-positive bacteria, including the important human pathogens Streptococcus pyogenes and Streptococcus pneumoniae. Thus, Streptococcus salivarius 5M6c may be a potential biological agent for the control of oronasopharynx-colonizing streptococcal pathogens or may be used as a probiotic bacterium. PMID:22101034

  2. In vitro capability of faropenem to select for resistant mutants of Streptococcus pneumoniae and Haemophilus influenzae.

    PubMed

    Kosowska-Shick, Klaudia; Clark, Catherine; Credito, Kim; Dewasse, Bonifacio; Beachel, Linda; Ednie, Lois; Appelbaum, Peter C

    2008-02-01

    When tested against nine strains of pneumococci and six of Haemophilus influenzae of various resistotypes, faropenem failed to select for resistant mutants after 50 days of consecutive subculture in subinhibitory concentrations. Faropenem also yielded low rates of spontaneous mutations against all organisms of both species. By comparison, resistant clones were obtained with macrolides, ketolides, and quinolones.

  3. Streptococcus pneumoniae resists intracellular killing by olfactory ensheathing cells but not by microglia

    PubMed Central

    Macedo-Ramos, Hugo; Ruiz-Mendoza, Susana; Mariante, Rafael M.; Guimarães, Erick V.; Quadros-de-Souza, Lucas C.; Paiva, Mauricio M.; Ferreira, Eliane de O.; Pinto, Tatiana C. A.; Teixeira, Lucia M.; Allodi, Silvana; Baetas-da-Cruz, Wagner

    2016-01-01

    Olfactory ensheathing cells (OECs) are a type of specialized glial cell currently considered as having a double function in the nervous system: one regenerative, and another immune. Streptococcus pneumoniae is a major agent of severe infections in humans, including meningitis. It is commonly found in the nasopharynx of asymptomatic carriers, and, under certain still unknown conditions, can invade the brain. We evaluated whether pneumococcal cells recovered from lysed OECs and microglia are able to survive by manipulating the host cell activation. An intracellular-survival assay of S. pneumoniae in OECs showed a significant number of bacterial CFU recovered after 3 h of infection. In contrast, microglia assays resulted in a reduced number of CFU. Electron-microscopy analysis revealed a large number of pneumococci with apparently intact morphology. However, microglia cells showed endocytic vesicles containing only bacterial cell debris. Infection of OEC cultures resulted in continuous NF-κB activation. The IFN-γ-induced increase of iNOS expression was reversed in infected OECs. OECs are susceptible to S. pneumoniae infection, which can suppress their cytotoxic mechanisms in order to survive. We suggest that, in contrast to microglia, OECs might serve as safe targets for pneumococci, providing a more stable environment for evasion of the immune system. PMID:27827453

  4. Controlled challenge experiment demonstrates substantial additive genetic variation in resistance of Nile tilapia (Oreochromis niloticus) to Streptococcus iniae

    USDA-ARS?s Scientific Manuscript database

    Streptococcus iniae is an etiologic agent of streptococcal disease in tilapia and is one of several Streptococcus spp. that negatively impact worldwide tilapia production. Methods for the prevention and control of S. iniae include vaccines, management strategies, and antibiotics. A complimentary pre...

  5. Preparation of Acid-Resistant Microcapsules with Shell-Matrix Structure to Enhance Stability of Streptococcus Thermophilus IFFI 6038.

    PubMed

    Zhou, Huan Bin; Chen, Jiashu; Li, Shunyi; Zhang, Jianpan; Zhu, Chun E; Ran, Hao; Luo, Meihua; Pan, Xin; Hu, Haiyan; Wu, Chuanbin

    2017-08-01

    Microencapsulation is an effective technology used to protect probiotics against harsh conditions. Extrusion is a commonly used microencapsulation method utilized to prepare probiotics microcapsules that is regarded as economical and simple to operate. This research aims to prepare acid-resistant probiotic microcapsules with high viability after freeze-drying and optimized storage stability. Streptococcus thermophilus IFFI 6038 (IFFI 6038) cells were mixed with trehalose and alginate to fabricate microcapsules using extrusion. These capsules were subsequently coated with chitosan to obtain chitosan-trehalose-alginate microcapsules with shell-matrix structure. Chitosan-alginate microcapsules (without trehalose) were also prepared using the same method. The characteristics of the microcapsules were observed by measuring the freeze-dried viability, acid resistance, and long-term storage stability of the cells. The viable count of IFFI 6038 in the chitosan-trehalose-alginate microcapsules was 8.34 ± 0.30 log CFU g(-1) after freeze-drying (lyophilization), which was nearly 1 log units g(-1) greater than the chitosan-alginate microcapsules. The viability of IFFI 6038 in the chitosan-trehalose-alginate microcapsules was 6.45 ± 0.09 log CFU g(-1) after 120 min of treatment in simulated gastric juices, while the chitosan-alginate microcapsules only measured 4.82 ± 0.22 log CFU g(-1) . The results of the long-term storage stability assay indicated that the viability of IFFI 6038 in chitosan-trehalose-alginate microcapsules was higher than in chitosan-alginate microcapsules after storage at 25 °C. Trehalose played an important role in the stability of IFFI 6038 during storage. The novel shell-matrix chitosan-trehalose-alginate microcapsules showed optimal stability and acid resistance, demonstrating their potential as a delivery vehicle to transport probiotics. © 2017 Institute of Food Technologists®.

  6. Host-derived probiotics Enterococcus casseliflavus improves resistance against Streptococcus iniae infection in rainbow trout (Oncorhynchus mykiss) via immunomodulation.

    PubMed

    Safari, Reza; Adel, Milad; Lazado, Carlo C; Caipang, Christopher Marlowe A; Dadar, Maryam

    2016-05-01

    The present study evaluated the benefits of dietary administration of host-derived candidate probiotics Enterococcus casseliflavus in juvenile rainbow trout Oncorhynchus mykiss. Experimental diets were prepared by incorporating the microorganisms in the basal feed at 3 inclusion levels (i.e. 10(7) CFU g(-1) of feed [T1], 10(8) CFU g(-1) of feed [T2], 10(9) CFU g(-1) of feed [T3]). The probiotic feeds were administered for 8 weeks, with a group fed with the basal diet serving as control. The effects on growth performance, gut health, innate immunity and disease resistance were evaluated. Results showed that growth performance parameters were significantly improved in T2 and T3 groups. Activities of digestive enzymes such as trypsin and lipase were significantly higher in these two groups as well. Gut micro-ecology was influenced by probiotic feeding as shown by the significant increase in intestinal lactic acid bacteria and total viable aerobic counts in T2 and T3. Humoral immunity was impacted by dietary probiotics as total serum protein and albumin were significantly elevated in T3. The levels of serum IgM significantly increased in all probiotic fed groups at week 8; with the T3 group registering the highest increment. Respiratory burst activity of blood leukocytes were significantly improved in T2 and T3. Hematological profiling further revealed that neutrophil counts significantly increased in all probiotic fed groups. Challenge test showed that probiotic feeding significantly improved host resistance to Streptococcus iniae infection, specifically in T2 and T3 where a considerable modulation of immune responses was observed. Taken together, this study demonstrated E. casseliflavus as a potential probiotics for rainbow trout with the capability of improving growth performance and enhancing disease resistance by immunomodulation.

  7. Activity of gemifloxacin against quinolone-resistant Streptococcus pneumoniae strains in vitro and in a mouse pneumonia model.

    PubMed

    Azoulay-Dupuis, E; Bédos, J P; Mohler, J; Moine, P; Cherbuliez, C; Peytavin, G; Fantin, B; Köhler, T

    2005-03-01

    Gemifloxacin is a novel fluoronaphthyridone quinolone with enhanced in vitro activity against Streptococcus pneumoniae. We investigated the activities of gemifloxacin and trovafloxacin, their abilities to select for resistance in vitro and in vivo, and their efficacies in a mouse model of acute pneumonia. Immunocompetent Swiss mice were infected with 10(5) CFU of a virulent, encapsulated S. pneumoniae strain, P-4241, or its isogenic parC, gyrA, parC gyrA, and efflux mutant derivatives (serotype 3); and leukopenic mice were infected with 10(7) CFU of two poorly virulent clinical strains (serotype 11A) carrying either a parE mutation or a parC, gyrA, and parE triple mutation. The drugs were administered six times every 12 h, starting at either 3 or 18 h postinfection. In vitro, gemifloxacin was the most potent agent against strains with and without acquired resistance to fluoroquinolones. While control mice died within 6 days, gemifloxacin at doses of 25 and 50 mg/kg of body weight was highly effective (survival rates, 90 to 100%) against the wild-type strain and against mutants harboring a single mutation, corresponding to area under the time-versus-serum concentration curve at 24 h (AUC(24))/MIC ratios of 56.5 to 113, and provided a 40% survival rate against a mutant with a double mutation (parC and gyrA). A total AUC(24)/MIC ratio of 28.5 was associated with poor efficacy and the emergence of resistant mutants. Trovafloxacin was as effective as gemifloxacin against mutants with single mutations but did not provide any protection against the mutant with double mutations, despite treatment with a high dose of 200 mg/kg. Gemifloxacin preferentially selected for parC mutants both in vitro and in vivo.

  8. Activity of Gemifloxacin against Quinolone-Resistant Streptococcus pneumoniae Strains In Vitro and in a Mouse Pneumonia Model

    PubMed Central

    Azoulay-Dupuis, E.; Bédos, J. P.; Mohler, J.; Moine, P.; Cherbuliez, C.; Peytavin, G.; Fantin, B.; Köhler, T.

    2005-01-01

    Gemifloxacin is a novel fluoronaphthyridone quinolone with enhanced in vitro activity against Streptococcus pneumoniae. We investigated the activities of gemifloxacin and trovafloxacin, their abilities to select for resistance in vitro and in vivo, and their efficacies in a mouse model of acute pneumonia. Immunocompetent Swiss mice were infected with 105 CFU of a virulent, encapsulated S. pneumoniae strain, P-4241, or its isogenic parC, gyrA, parC gyrA, and efflux mutant derivatives (serotype 3); and leukopenic mice were infected with 107 CFU of two poorly virulent clinical strains (serotype 11A) carrying either a parE mutation or a parC, gyrA, and parE triple mutation. The drugs were administered six times every 12 h, starting at either 3 or 18 h postinfection. In vitro, gemifloxacin was the most potent agent against strains with and without acquired resistance to fluoroquinolones. While control mice died within 6 days, gemifloxacin at doses of 25 and 50 mg/kg of body weight was highly effective (survival rates, 90 to 100%) against the wild-type strain and against mutants harboring a single mutation, corresponding to area under the time-versus-serum concentration curve at 24 h (AUC24)/MIC ratios of 56.5 to 113, and provided a 40% survival rate against a mutant with a double mutation (parC and gyrA). A total AUC24/MIC ratio of 28.5 was associated with poor efficacy and the emergence of resistant mutants. Trovafloxacin was as effective as gemifloxacin against mutants with single mutations but did not provide any protection against the mutant with double mutations, despite treatment with a high dose of 200 mg/kg. Gemifloxacin preferentially selected for parC mutants both in vitro and in vivo. PMID:15728901

  9. Exploration of fluoroquinolone resistance in Streptococcus pyogenes: comparative structure analysis of wild-type and mutant DNA gyrase.

    PubMed

    Shafreen, Raja Mohmed Beema; Selvaraj, Chandrabose; Singh, Sanjeev Kumar; Pandian, Shunmugiah Karutha

    2013-06-01

    Quinolone resistance-determining region is known to be the druggability site of the target protein that undergoes frequent mutation and thus renders quinolone resistance. In the present study, ligands were tested for their inhibitory activity against DNA gyrase of Streptococcus pyogenes involved in DNA replication. In silico mutational analysis on modelled gyrase A revealed that GLU85 had the most possible interactions with all the ligands used for the study. The amino acid residue GLU85 had also been predicted with an essential role of maintaining the three-dimensional structure of the protein. When introduced with a mutation (GLU 85 LYS) on this particular residue, it had readily denatured the whole α-helix (from 80 to 90 amino acids). This was confirmed through the molecular dynamics simulation and revealed that this single mutation can cause many functional and structural changes. Furthermore, LYS85 mutation has altered the original secondary structure of the protein, which in turn led to the steric hindrance during the ligand-receptor interaction. The results based on the G-score revealed that ligands have reduced interaction with the mutant protein. The semisynthetic fluoroquinolone 6d, which is an exception, forms a strong interaction with the mutant protein and was experimentally verified using the antimicrobial test. Hence, the present study unravels the fact that mutation at the drug binding site is the major cause for different level of resistance by the S. pyogenes when exposed against the varying concentrations of the fluoroquinolones. Furthermore, a comparative assessment of quinolone derivative with the older generation fluoroquinolones will be of great impact for S. pyogenes-related infections. Copyright © 2013 John Wiley & Sons, Ltd.

  10. Respiratory Commensal Bacteria Corynebacterium pseudodiphtheriticum Improves Resistance of Infant Mice to Respiratory Syncytial Virus and Streptococcus pneumoniae Superinfection.

    PubMed

    Kanmani, Paulraj; Clua, Patricia; Vizoso-Pinto, Maria G; Rodriguez, Cecilia; Alvarez, Susana; Melnikov, Vyacheslav; Takahashi, Hideki; Kitazawa, Haruki; Villena, Julio

    2017-01-01

    Corynebacterium pseudodiphtheriticum is a Gram-positive bacterium found as a member of the normal microbiota of the upper respiratory tract. It was suggested that C. pseudodiphtheriticum may be potentially used as a next-generation probiotic for nasal application, although no deep studies were performed in this regard. We hypothesized that human isolate C. pseudodiphtheriticum strain 090104 is able to modulate the respiratory innate immune response and beneficially influence the resistance to viral and bacterial infections. Therefore, in the present study we investigated how the exposure of infant mice to nasal priming with viable or non-viable C. pseudodiphtheriticum 090104 influences the respiratory innate immune response triggered by Toll-like receptor (TLR)-3 activation, the susceptibility to primary Respiratory Synsytial Virus (RSV) infection, and the resistance to secondary Streptococcus pneumoniae pneumonia. We demonstrated that the nasal priming with viable C. pseudodiphtheriticum 090104 differentially modulated TLR3-mediated innate antiviral immune response in the respiratory tract of infant mice, improving their resistance to primary RSV infection, and secondary pneumococcal pneumonia. In association with the protection against RSV-pneumococcal superinfection, we found that viable C. pseudodiphtheriticum improved lung CD3(+)CD4(+)IFN-γ(+), and CD3(+)CD4(+)IL-10(+) T cells as well as CD11c(+)SiglecF(+)IFN-β(+) alveolar macrophages. Of interest, non-viable bacteria did not have the same protective effect, suggesting that C. pseudodiphtheriticum colonization is needed for achieving its protective effect. In conclusion, we present evidence that nasal application of viable C. pseudodiphtheriticum could be thought as an alternative to boost defenses against RSV and secondary pneumococcal pneumonia, which should be further studied and validated in clinical trials. Due to the absence of a long-lasting immunity, re-infection with RSV throughout life is common

  11. The S2 Cu(i) site in CupA from Streptococcus pneumoniae is required for cellular copper resistance.

    PubMed

    Fu, Yue; Bruce, Kevin E; Wu, Hongwei; Giedroc, David P

    2016-01-01

    Pathogenic bacteria have evolved copper homeostasis and resistance systems for fighting copper toxicity imposed by the human immune system. Streptococcus pneumoniae is a respiratory pathogen that encodes an obligatorily membrane-anchored Cu(i) binding protein, CupA, and a P1B-type ATPase efflux transporter, CopA. The soluble, cytoplasmic domain of CupA (sCupA) contains a binuclear Cu(i) cluster consisting of S1 and S2 Cu(i) ions. The NMR solution structure of apo-sCupA reveals the same cupredoxin fold of Cu2-sCupA, except that the Cu(i) binding loop (residues 112-116, harboring S2 Cu ligands M113 and M115) is highly dynamic as documented by both backbone and side chain methionine methyl order parameters. In contrast to the more solvent exposed, lower affinity S2 Cu site, the high affinity S1 Cu-coordinating cysteines (C74, C111) are pre-organized in the apo-sCupA structure. Biological experiments reveal that the S1 site is largely dispensable for cellular Cu resistance and may be involved in buffering low cytoplasmic Cu(i). In contrast, the S2 site is essential for Cu resistance. Expression of a chimeric CopZ chaperone fused to the CupA transmembrane helix does not protect S. pneumoniae from copper toxicity and substitution of a predicted cytoplasm-facing Cu(i) entry metal-binding site (MBS) on CopA also gives rise to a Cu-sensitivity phenotype. These findings suggest that CupA and CopA may interact and filling of the CupA S2 site with Cu(i) results in stimulation of cellular copper efflux by CopA.

  12. [Antibiotic resistance analysis of Streptococcus pneumoniae isolates from the hospitalized children in Shanxi Children's Hospital from 2012 to 2014].

    PubMed

    Ge, L L; Han, Z Y; Liu, A H; Zhu, L; Meng, J H

    2017-02-02

    Objective: To investigate the antibiotic resistance status of Streptococcus pneumoniae isolates from hospitalized children in Shanxi Children's Hospital. Method: E-test and Kirby-Bauer methods were applied to determine drug sensitivity of the isolates collected from the body fluid specimens of hospitalized children in Shanxi Children's Hospital from January 2012 to December 2014. The antimicrobial sensitivity and minimum inhibitory concentration (MIC) of Streptococcus pneumoniae to the conventional antibiotics were analyzed, in order to compare the annual trends of non-invasive isolates, while the differentiation of sensitivity from specimens. The comparison of rates was performed by Chi-squared test and Fisher's exact test. Result: A total of 671 isolates of streptococcus pneumoniae were obtained, which could be divided as non-invasive isolates(607), invasive isolates from non-cerebrospinal fluid(non-CSF)(40) and invasive isolates from cerebrospinal fluid(CSF)(24). The antimicrobial sensitivity(isolates(%)) of the 671 isolates were respectively vancomycin 671(100.0%), linezolid 671(100.0%), levofloxacin 665(99.1%), penicillin 595(88.7%), ceftriaxone 516(76.9%), cefotaxime 512(76.3%), sulfamethoxazole-trimethoprin(SMZ-TMP) 103(15.4%), clindamycin 28(4.2%), tetracycline 26(3.9%), erythromycin 12(1.8%). From 2012 to 2014, the susceptibility rates of non-invasive isolates to penicillin every year were 95.0%(96/101), 97.3%(110/113), 87.3%(343/393), respectively, and there was significant difference among the three years(χ(2)=13.266, P<0.05), and the values of MIC(50, )MIC(90) and the maximum values of MIC(mg/L) of penicillin were 0.064, 2.000, 6.000 in 2012, which grew up to 1.000, 3.000, 16.000 in 2014. There was no significant difference in the susceptibility rate of non-invasive isolates to ceftriaxone and cefotaxime during these three years, (χ(2)=1.172, 1.198, both P>0.05). On the other hand, the values of MIC(50, )MIC(90) and the maximum value of MIC(mg/L) of

  13. Disease burden and antimicrobial resistance of invasive group B streptococcus among infants in China: a protocol for a national prospective observational study.

    PubMed

    Ji, Wenjing; Liu, Haiying; Jin, Zhengjiang; Wang, Aimin; Mu, Xiaoping; Qin, Xiaosong; Wang, Weidong; Gao, Chunyan; Zhu, Yuning; Feng, Xiaodan; Lei, Jine; She, Shangyang; Jiang, Lan; Liu, Jing; Yang, Shuhua; Liu, Zeshi; Li, Gang; Li, Qiuhong; Guo, Dawen; Aziz, Muhammad Majid; Gillani, Ali Hassan; Fang, Yu

    2017-05-31

    Group B Streptococcus (GBS) is a cause of neonatal sepsis, pneumonia, and meningitis that can lead to neurological sequelae in infants less than 3 months of age. The GBS disease burden is not known in China, therefore it cannot receive major attention. The main objectives of this study are the evaluation of the incidence of neonatal GBS infection, GBS case-fatality ratio, its serotypes and genotypes, bacterial resistance, clinical treatment and outcomes in China. We are conducting a nation-wide, population-based, multi-center, prospective, observational cohort study in China from May 2016 to December 2017. Eighteen large urban tertiary care hospitals from 16 provinces were selected that cover the eastern, southern, western, northern and central regions of China. Meanwhile, we retrospectively collected data and GBS strains from January 2015 to April 2016 from selected hospitals. The incidence rate per 1000 live births will be defined as the total number of confirmed GBS cases born in the selected hospitals divided by the number of live births in the hospitals during the study period. All GBS cases detected in selected hospitals will be used to calculate the case-fatality ratio and for the typing analysis. GBS isolates will be serotyped using the Strep-B-Latex® rapid latex agglutination test for serotyping of Group B streptococci. Multi-locus sequence typing (MLST) will be performed by sequencing the internal fragments of seven house-keeping genes. Antimicrobial susceptibility will be tested per interpretive standards established by the Clinical and Laboratory Standards Institute. The presence of the common resistance genes ermA, ermB, mefA, tetI, tetO and tetM will be tested by PCR. We are conducting the first national study to estimate the invasive GBS disease burden and antimicrobial resistance of GBS among infants in China. Study findings will provide important evidence for improving clinical practice to ensure timely diagnosis of GBS disease and decisions for

  14. Transcriptional plasticity promotes primary and acquired resistance to BET inhibition.

    PubMed

    Rathert, Philipp; Roth, Mareike; Neumann, Tobias; Muerdter, Felix; Roe, Jae-Seok; Muhar, Matthias; Deswal, Sumit; Cerny-Reiterer, Sabine; Peter, Barbara; Jude, Julian; Hoffmann, Thomas; Boryń, Łukasz M; Axelsson, Elin; Schweifer, Norbert; Tontsch-Grunt, Ulrike; Dow, Lukas E; Gianni, Davide; Pearson, Mark; Valent, Peter; Stark, Alexander; Kraut, Norbert; Vakoc, Christopher R; Zuber, Johannes

    2015-09-24

    Following the discovery of BRD4 as a non-oncogene addiction target in acute myeloid leukaemia (AML), bromodomain and extra terminal protein (BET) inhibitors are being explored as a promising therapeutic avenue in numerous cancers. While clinical trials have reported single-agent activity in advanced haematological malignancies, mechanisms determining the response to BET inhibition remain poorly understood. To identify factors involved in primary and acquired BET resistance in leukaemia, here we perform a chromatin-focused RNAi screen in a sensitive MLL-AF9;Nras(G12D)-driven AML mouse model, and investigate dynamic transcriptional profiles in sensitive and resistant mouse and human leukaemias. Our screen shows that suppression of the PRC2 complex, contrary to effects in other contexts, promotes BET inhibitor resistance in AML. PRC2 suppression does not directly affect the regulation of Brd4-dependent transcripts, but facilitates the remodelling of regulatory pathways that restore the transcription of key targets such as Myc. Similarly, while BET inhibition triggers acute MYC repression in human leukaemias regardless of their sensitivity, resistant leukaemias are uniformly characterized by their ability to rapidly restore MYC transcription. This process involves the activation and recruitment of WNT signalling components, which compensate for the loss of BRD4 and drive resistance in various cancer models. Dynamic chromatin immunoprecipitation sequencing and self-transcribing active regulatory region sequencing of enhancer profiles reveal that BET-resistant states are characterized by remodelled regulatory landscapes, involving the activation of a focal MYC enhancer that recruits WNT machinery in response to BET inhibition. Together, our results identify and validate WNT signalling as a driver and candidate biomarker of primary and acquired BET resistance in leukaemia, and implicate the rewiring of transcriptional programs as an important mechanism promoting

  15. ABA receptor PYL9 promotes drought resistance and leaf senescence

    PubMed Central

    Zhao, Yang; Chan, Zhulong; Gao, Jinghui; Xing, Lu; Cao, Minjie; Yu, Chunmei; Hu, Yuanlei; You, Jun; Shi, Haitao; Zhu, Yingfang; Gong, Yuehua; Mu, Zixin; Wang, Haiqing; Deng, Xin; Wang, Pengcheng; Bressan, Ray A.; Zhu, Jian-Kang

    2016-01-01

    Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 double mutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress. PMID:26831097

  16. ABA receptor PYL9 promotes drought resistance and leaf senescence.

    PubMed

    Zhao, Yang; Chan, Zhulong; Gao, Jinghui; Xing, Lu; Cao, Minjie; Yu, Chunmei; Hu, Yuanlei; You, Jun; Shi, Haitao; Zhu, Yingfang; Gong, Yuehua; Mu, Zixin; Wang, Haiqing; Deng, Xin; Wang, Pengcheng; Bressan, Ray A; Zhu, Jian-Kang

    2016-02-16

    Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 double mutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress.

  17. Molecular architecture of Streptococcus pneumoniae surface thioredoxin-fold lipoproteins crucial for extracellular oxidative stress resistance and maintenance of virulence

    PubMed Central

    Saleh, Malek; Bartual, Sergio G; Abdullah, Mohammed R; Jensch, Inga; Asmat, Tauseef M; Petruschka, Lothar; Pribyl, Thomas; Gellert, Manuela; Lillig, Christopher H; Antelmann, Haike; Hermoso, Juan A; Hammerschmidt, Sven

    2013-01-01

    The respiratory pathogen Streptococcus pneumoniae has evolved efficient mechanisms to resist oxidative stress conditions and to displace other bacteria in the nasopharynx. Here we characterize at physiological, functional and structural levels two novel surface-exposed thioredoxin-family lipoproteins, Etrx1 and Etrx2. The impact of both Etrx proteins and their redox partner methionine sulfoxide reductase SpMsrAB2 on pneumococcal pathogenesis was assessed in mouse virulence studies and phagocytosis assays. The results demonstrate that loss of function of either both Etrx proteins or SpMsrAB2 dramatically attenuated pneumococcal virulence in the acute mouse pneumonia model and that Etrx proteins compensate each other. The deficiency of Etrx proteins or SpMsrAB2 further enhanced bacterial uptake by macrophages, and accelerated pneumococcal killing by H2O2 or free methionine sulfoxides (MetSO). Moreover, the absence of both Etrx redox pathways provokes an accumulation of oxidized SpMsrAB2 in vivo. Taken together our results reveal insights into the role of two extracellular electron pathways required for reduction of SpMsrAB2 and surface-exposed MetSO. Identification of this system and its target proteins paves the way for the design of novel antimicrobials. PMID:24136784

  18. The comparative development of elevated resistance to macrolides in community-acquired pneumonia caused by Streptococcus pneumoniae.

    PubMed

    Yayan, Josef

    2014-01-01

    Community-acquired pneumonia (CAP) is an acute inflammation of the lungs, which is often caused by Streptococcus pneumoniae. CAP is the leading cause of death by infectious disease in industrialized countries. Therefore, an immediate and effective antibiotic therapy is of great importance for the nonfatal outcome of the disease. The literature contains increasing data about the development of resistance to antibiotics that are used for the treatment of CAP caused by S. pneumoniae; this article also examines the possible development of resistance to antibiotics in S. pneumoniae in recent years. Within the study period of 2004-2014, all hospital charts from patients with CAP caused by S. pneumoniae were collected from the Department of Internal Medicine, Saarland University Medical Center, Homburg/Saar, Germany. The tracheal secretions of S. pneumoniae in CAP patients were obtained by bronchoalveolar lavage; bronchial aspirates were obtained through flexible bronchoscopy and directly from sputum, and blood cultures were examined microbiologically for microorganisms. From a total of 100 patients with CAP caused by S. pneumoniae, 23 (53.49% [34.78% female], 95% confidence interval, 38.58-68.4) patients with a mean age of 59.78 ± 15.77 years met the inclusion criteria of this investigation. These patients were compared to a total of 20 (46.51% [35% female], 95% confidence interval, 31.6-61.42) patients with a mean age of 58.9 ± 13.36 years with CAP who were infested with S. pneumoniae. In the latter group, the streptococcal antigen was detected in pulmonary aspirations by bronchoscopy or in urine using polymerase chain reaction and a rapid pneumococcal test. Penicillin G and vancomycin had a high rate of sensitivity on the antibiogram for S. pneumoniae, which was obtained by bronchoalveolar lavage, bronchial aspirates through flexible bronchoscopy, and directly from sputum. Even though the rates obtained were without statistical significance, S. pneumoniae had a high

  19. Comparative in vitro activity of penicillin G, levofloxacin, moxifloxacin, telithromycin, pristinamycin, quinupristin-dalfopristin and linezolid against ofloxacin-intermediate and -resistant Streptococcus pneumoniae.

    PubMed

    Frédénucci, I; Chomarat, M; Bercion, R; Carricajo, A; Celard, M; Croizé, J; Delubac, F; Fèvre, D; Fuhrmann, C; Helfre, M; Letouzey, M N; Lelièvre, H; Mandjee, A; Marthelet, P; Meley, R; Perrier-Gros-Claude, J D; Ros, A; Roure, C; Smati, S; Thierry, J; Tous, J

    2002-10-01

    Screening by ofloxacin disk was carried out on 1158 strains of Streptococcus pneumoniae in order to investigate the in vitro bacteriostatic activity of penicillin G, levofloxacin, moxifloxacin, telithromycin, linezolid, pristinamycin and quinupristin-dalfopristin against ofloxacin-intermediate and -resistant S. pneumoniae strains. It was concluded that these new antimicrobial agents could be useful for the treatment of pneumococcal infections caused by penicillin-sensitive and -resistant S. pneumoniae, and would represent a valid therapeutic option for patients allergic to beta-lactams, should they prove to be potent in vivo.

  20. [Morphological changes in penicillin-resistant Streptococcus pneumoniae and beta-lactamase-nonproducing, ampicillin-resistant Haemophilus influenzae after exposure to oral antibacterial agents].

    PubMed

    Chiba, Naoko; Morozumi, Miyuki; Ubukata, Kimiko

    2012-10-01

    Morphological changes in penicillin-resistant Streptococcus pneumoniae (PRSP) and beta-lactamase-nonproducing, ampicillin-resistant Haemophilus influenzae (BLNAR) after exposure to oral antibacterial agents could be observed over time under a phase-contrast microscope. Morphological changes in BLNAR were also observed using a scanning electron microscope. The organisms used in this study were ME19F strain identified as genotypic(g) gPRSP (serotype: 19F) and JPH002 strain identified as gBLNAR (serotype: b). The antibacterial agents used were amoxicillin (AMPC), cefditoren (CDTR), tebipenem (TBPM), and tosufloxacin (TFLX). The concentration of each antibacterial agent to which the bacteria were exposed was set at the blood level one hour after Cmax when administered to children at the usual dose. Bacteriolysis of gPRSP cells started after exposure of only 20minutes to TBPM, and 90% of the cells were lysed within 2 hours. A high bactericidal action of TBPM on gPRSP was supported by these findings. When gBLNAR was exposed to AMPC and TBPM, lysis from spheroplasts and cells with vacuoles were sometimes observed. In contrast, after gBLNAR was exposed to CDTR, lysis occurred after marked filamentation in the cells, but after exposure to TFLX, cells deduced to be killed after mild filamentation without lysis. Time-dependent morphological changes that reflect the differences in bactericidal activity and PBP affinity among beta-lactams provide beneficial information to select antibacterial agents.

  1. Development and efficacy of a novobiocin-resistant Streptococcus iniae as a novel vaccine in Nile tilapia (Oreochromis niloticus).

    PubMed

    Pridgeon, Julia W; Klesius, Phillip H

    2011-08-11

    A novel attenuated Streptococcus iniae vaccine was developed from a virulent strain of Streptococcus iniae (ISET0901) through selection for novobiocin resistance (named ISNO). The safety of ISNO was then evaluated in Nile tilapia (Oreochromis niloticus) through intraperitoneal (IP) injection. When male tilapia (average weight 10 g) were IP injected with 2×10(7) colony-forming units (CFU) of the attenuated S. iniae vaccine strain, no fish died. However, when the same age and size matched tilapia were IP injected with 2×10(7) and 1×10(5)CFU of the virulent parent strain of S. iniae, 100 and 90% fish died, respectively. Backpassage safety studies revealed that ISNO was unable to revert back to a virulent state. When IP vaccinated fish were challenged by the virulent ISET0901 strain of S. iniae, relative percent survival (RPS) values of vaccinated fish at 14, 28, 60, 90, and 180 days post ISNO vaccination (dpv) were 100, 100, 100, 89, and 75%, respectively, The RPS values of ISNO vaccinated fish (IP vaccination) against infections by five heterologous virulent strains of S. iniae (F3CB, 102 F1K, 405 F1K, IF6, and ARS60) at 60 dpv were 78, 90, 100, 100, and 100%, respectively. When tilapia were IP vaccinated by ISNO at dose of 1×10(2), 1×10(3), 1×10(4), 1×10(5), 1×10(6), and 1×10(7)CFU/fish, RPS values at 28 dpv were 81, 94, 100, 100, 100, and 100%, respectively. At 28 dpv, RPS of vaccinated fish by ISNO through bath immersion (1×10(7)CFU/ml) was 88%. ELISA results revealed that protection elicited by ISNO was due to antibody- as well as cell- mediated immunity. Our results suggest that ISNO could be used as a novel safe and efficacious vaccine to protect Nile tilapia from S. iniae infections.

  2. [Genetic analysis of multidrug-resistant Streptococcus pneumoniae including meropenem resistance that was isolated from elderly residents with pneumonia in nursing-care facilities].

    PubMed

    Ota, Kazuko; Chiba, Naoko; Sato, Kentaro; Nara, Syoetu; Kato, Satoko; Kanazawa, Hisao; Ikejima, Shin; Takahashi, Yoshihiro; Iwata, Satoshi; Ubukata, Kimiko

    2014-07-01

    From February to December 20XX, penicillin-resistant Streptococcus pneumoniae (PRSP) showing MICs of 16-32 microg/mL to cefotaxime (CTX) and 4-8 microg/mL to meropenem (MEPM) were isolated from 6 patients hospitalized at the general hospital S (2 cases) and hospital A (4 cases), close to the hospital S. Five elderly patients among these six cases came from nursing care facilities or nursing care-related medical facilities. All elderly persons (mean age: 81.7 years) were diagnosed as having pneumonia at the time of admission and the problematic PRSP was isolated from sputum samples collected on admission. Notably, all of these PRSP isolates simultaneously showed high resistance to macrolide agents mediated by an erm (B) gene and to fluoroquinolone agents via mutations in the gyrA and parC genes. Eventually, they were identified as multidrug-resistant S. pneumoniae (MDRSP) with high resistance to many agents. The capsule type of all strains was serotype 19F and multilocus sequence typing (MLST) revealed that they belonged to clonal complex (CC) 7993, which has not been reported before. It was thus concluded that the MDRSP that had spread within the nursing facilities was transmitted to the general hospitals via the elderly inpatients with pneumonia caused by these agents. Although one case finally had a poor outcome, the pneumococcal infection was not the direct trigger of the event. The current ratio of MDRSP is concluded to be very low. However, general hospitals that accept patients for therapeutic purposes from nursing-care facilities have to share epidemiological information in a timely manner with the nursing homes to prevent nosocomial infections.

  3. Prevalence and Molecular Genetics of Macrolide Resistance among Streptococcus pneumoniae Isolates Collected in Finland in 2002

    PubMed Central

    Rantala, M.; Huikko, S.; Huovinen, P.; Jalava, J.

    2005-01-01

    The prevalence and mechanisms of macrolide resistance among 1,007 clinical pneumococcal isolates collected in Finland were investigated. Of these, 217 (21.5%) were resistant to erythromycin and 11% to clindamycin. Among the erythromycin-resistant isolates, mef(E) was present in 95 isolates (44%), mef(A) was present in 12 isolates (6%), and erm(B) was present in 90 isolates (41%). A double mechanism, mef(E) and erm(B), was detected in five isolates (2%). Ribosomal mutation was detected in 14 (6%) macrolide-resistant isolates in which no other determinant was found. Based on the telithromycin MICs, two groups of isolates were formed: 83.3% of the isolates belonged to a major group for which the telithromycin MIC range was ≤0.008 to 0.063 μg/ml, and 16.7% belonged to a minor group for which the telithromycin MIC range was 0.125 to 8 μg/ml. All except three isolates in the minor population carried a macrolide resistance gene. PMID:16189096

  4. Dissemination of an erythromycin-resistant penicillin-nonsusceptible Streptococcus pneumoniae Poland(6B)-20 clone in Argentina.

    PubMed

    Bonofiglio, Laura; Regueira, Mabel; Pace, Julio; Corso, Alejandra; García, Ernesto; Mollerach, Marta

    2011-03-01

    Prevalence of serotype 6B penicillin (PEN)-nonsusceptible Streptococcus pneumoniae significantly increased from 15.8% (1993-1997) to 67.3% (1998-2002) (p<0.001) in Argentina. Serogroup 6 ranks fourth among different capsular types within invasive isolates from Argentinean patients <6 years of age. To evaluate whether the increase in PEN resistance in serotype 6B pneumococci was due to the dissemination of one or more clones, the genetic diversity of 93 S. pneumoniae serotype 6B isolates was analyzed. Five BOX-polymerase chain reaction types were obtained (65.5% isolates) and a group of 15 isolates, representing 41.6% of those having a decreased susceptibility to PEN, were further characterized. The antibiotype of these isolates showed their multiresistance, with 100% of the isolates being resistant to erythromycin, 80% to tetracycline, and 73.3% to trimethoprim-sulfamethoxazole. Of the 15 isolates, 13 belonged to the same pulsed-field gel electrophoresis type and galU cluster and were members of the same clone. The identity of the clone was confirmed in four isolates by multilocus sequence typing. The sequence type found (ST315) corresponds to the Poland(6B)-20 clone. In summary, BOX-polymerase chain reaction, pulsed-field gel electrophoresis, and galU polymorphism were useful tools to detect the presence of a clone whose identity was confirmed by multilocus sequence typing. The isolates belonging to Poland(6B)-20 found in this work are described for the first time in Latin America.

  5. Amoxicillin is effective against penicillin-resistant Streptococcus pneumoniae strains in a mouse pneumonia model simulating human pharmacokinetics.

    PubMed

    Abgueguen, Pierre; Azoulay-Dupuis, Esther; Noel, Violaine; Moine, Pierre; Rieux, Veronique; Fantin, Bruno; Bedos, Jean-Pierre

    2007-01-01

    High-dose oral amoxicillin (3 g/day) is the recommended empirical outpatient treatment of community-acquired pneumonia (CAP) in many European guidelines. To investigate the clinical efficacy of this treatment in CAP caused by Streptococcus pneumoniae strains with MICs of amoxicillin > or =2 microg/ml, we used a lethal bacteremic pneumonia model in leukopenic female Swiss mice with induced renal failure to replicate amoxicillin kinetics in humans given 1 g/8 h orally. Amoxicillin (15 mg/kg of body weight/8 h subcutaneously) was given for 3 days. We used four S. pneumoniae strains with differing amoxicillin susceptibility and tolerance profiles. Rapid bacterial killing occurred with an amoxicillin-susceptible nontolerant strain: after 4 h, blood cultures were negative and lung homogenate counts under the 2 log(10) CFU/ml detection threshold (6.5 log(10) CFU/ml in controls, P < 0.01). With an amoxicillin-intermediate nontolerant strain, significant pulmonary bacterial clearance was observed after 24 h (4.3 versus 7.9 log(10) CFU/ml, P < 0.01), and counts were undetectable 12 h after treatment completion. With an amoxicillin-intermediate tolerant strain, 24-h bacterial clearance was similar (5.4 versus 8.3 log(10) CFU/ml, P < 0.05), but 12 h after treatment completion, lung homogenates contained 3.3 log(10) CFU/ml. Similar results were obtained with an amoxicillin-resistant and -tolerant strain. Day 10 survival rates were usually similar across strains. Amoxicillin with pharmacokinetics simulating 1 g/8 h orally in humans is bactericidal in mice with pneumonia due to S. pneumoniae for which MICs were 2 to 4 microg/ml. The killing rate depends not only on resistance but also on tolerance of the S. pneumoniae strains.

  6. Epidemiological study on the penicillin resistance of clinical Streptococcus pneumoniae isolates identified as the common sequence types.

    PubMed

    Wei, Gao; Wei, Shi; Changhui, Chen; Denian, Wen; Jin, Tian; Kaihu, Yao

    2016-10-20

    There were some limitation in the current interpretation about the penicillin resistance mechanism of clinical Streptococcus pneumoniae isolates at the strain level. To explore the possibilities of studying the mechanism based on the sequence types (ST) of this bacteria, 488 isolates collected in Beijing from 1997-2014 and 88 isolates collected in Youyang County, Chongqing and Zhongjiang County, Sichuan in 2015 were analyzed by penicillin minimum inhibitory concentration (MIC) distribution and annual distribution. The results showed that the penicillin MICs of the all isolates covering by the given ST in Beijing have a defined range, either <0.25 mg/L or≥0.25 mg/L, except for the ST342. The isolates with penicillin MIC <0.25 mg/L were mainly collected before 2001, after which the isolates with MIC≥0.25 mg/L occurred and became the major population gradually. This law of year distribution, however, was not obvious for any specific ST. The isolates covering by any given ST could be determined with different penicillin MICs in the first few years after it was identified. The penicillin MIC of isolates identified as common STs and collected in Youyang County, Chongqing and Sichuan Zhongjiang County, including the ST271, ST320 and ST81, was around 0.25~2 mg/L (≥0.25 mg/L). Our study revealed the epidemiological distribution of penicillin MICs of the given STs determined in clinical S. pneumoniae isolates, suggesting that it is reasonable to research the penicillin resistance mechanism based on the STs of this bacteria.

  7. In vitro activity of older and newer fluoroquinolones against efflux-mediated high-level ciprofloxacin-resistant Streptococcus pneumoniae.

    PubMed

    Daporta, Matilde Trigo; Muñoz Bellido, Juan Luis; Guirao, Genoveva Yagüe; Hernández, Manuel Segovia; García-Rodríguez, José Angel

    2004-08-01

    The effect of high-level efflux activity on the MICs of fluoroquinolones against Streptococcus pneumoniae in the absence of topoisomerase mutations leading to fluoroquinolones resistance was investigated. A S. pneumoniae ATCC 46619-derived strain with high-level efflux activity was obtained (SP-25A). Both the parent and obtained strains were tested against efflux substrates acriflavine (Acr) and ethidium bromide (EtBr), and against norfloxacin (NFX), ciprofloxacin (CFX), levofloxacin (LFX), moxifloxacin (MFX), trovafloxacin (TVX) and sitafloxacin (SFX), in presence and absence of the efflux pump inhibitor reserpine. gyrA, gyrB, parC and parE QRDR genes were amplified by PCR and sequenced. MICs of NFX and CFX against SP-25A were 64-fold higher than parent strain MICs (256 mg/L versus 4 mg/L and 64 mg/L versus 1mg/L, respectively). MIC of LFX increased from 1 to 4 mg/L and MICs of MFX, TVX and SFX remained virtually unchanged (0.1-0.2 mg/L). MICs of Acr and EtBr against SP-25A were 8- and 16-fold higher than against parent strains. In both cases, reserpine reverted MICs to the parent strain values (1 and 0.2 mg/L). Only parE showed two mutations leading to a Pro(454) --> Ser and Glu(443) changes, which have previously been shown not to lead to significant fluoroquinolones MIC increases. SP-25A showed a significant increase of MICs of the hydrophilic fluoroquinolones, apparently derived only from efflux activity. Efflux activity, at these high levels, can lead to high-level resistance to older hydrophilic fluoroquinolones, but does affect newer fluoroquinolones such as moxifloxacin, trovafloxacin and sitafloxacin.

  8. IsaB inhibits autophagic flux to promote host transmission of methicillin-resistant Staphylococcus aureus

    PubMed Central

    Liu, Pei-Feng; Cheng, Jin-Shiung; Sy, Cheng-Len; Huang, Wei-Chun; Yang, Hsiu-Chen; Gallo, Richard L.; Huang, Chun-Ming; Shu, Chih-Wen

    2015-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major nosocomial pathogen that is widespread in both health care facilities and the community at large as a result of direct host-to-host transmission. Several virulence factors are associated with pathogen transmission to naive hosts. Immunodominant surface antigen B (IsaB) is a virulence factor that helps Staphylococcus aureus to evade the host defense system. However, the mechanism of IsaB on host transmissibility remains unclear. We found that IsaB expression was elevated in transmissible MRSA. Wild-type isaB strains inhibited autophagic flux to promote bacterial survival and elicit inflammation in THP-1 cells and mouse skin. MRSA isolates with increased IsaB expression showed decreased autophagic flux, and the MRSA isolate with the lowest IsaB expression showed increased autophagic flux. In addition, recombinant IsaB rescued the virulence of the isaB deletion strain and increased the Group A streptococcus (GAS) virulence in vivo. Together, these results reveal that IsaB diminishes autophagic flux, thereby allowing MRSA to evade host degradation. These findings suggest that IsaB is a suitable target for preventing or treating MRSA infection. PMID:26134948

  9. TET1 promotes cisplatin-resistance via demethylating the vimentin promoter in ovarian cancer.

    PubMed

    Han, Xi; Zhou, Yuanyuan; You, Yuanyi; Lu, Jiaojiao; Wang, Lijie; Hou, Huilian; Li, Jing; Chen, Wei; Zhao, Le; Li, Xu

    2017-04-01

    The development of chemo-resistance impairs the outcome of the first line platinum-based chemotherapies for ovarian cancer. Deregulation of DNA methylation/demethylation provides a critical mechanism for the occurrence of chemo-resistance. The ten-eleven translocation (TET) family of dioxygenases including TET1/2/3 plays an important part in DNA demethylation, but their roles in cisplatin resistance have not been elucidated. Using cisplatin-sensitive and cisplatin-resistant ovarian cancer cell models, we found that TET1 was significantly upregulated in cisplatin-resistant CP70 cells compared with that in cisplatin-sensitive A2780 cells. Ectopic expression of TET1 in A2780 cells promoted cisplatin resistance and decreased cytotoxicity induced by cisplatin, while inhibition of TET1 by siRNA transfection in CP70 cells attenuated cisplatin resistance and enhanced cytotoxicity of cisplatin. Increased TET1 induced re-expression of vimentin through active DNA demethylation, and cause partial epithelial-to-mesenchymal (EMT) in A2780 cells. Contrarily, knocking down of TET1 in CP70 cells reduced vimentin expression and reversed EMT process. Immunohistochemical analysis of TET1 in human ovarian cancer tissues revealed that TET1 existed in nucleus and cytoplasm in ovarian cancer tissues. And the expression of nuclear TET1 was positively correlated with residual tumor and chemotherapeutic response. Thus, TET1 expression causes resistance to cisplatin and one of the targets of TET1 action is vimentin in ovarian cancer.

  10. The Efflux Pump Inhibitor Reserpine Selects Multidrug-Resistant Streptococcus pneumoniae Strains That Overexpress the ABC Transporters PatA and PatB▿ †

    PubMed Central

    Garvey, Mark I.; Piddock, Laura J. V.

    2008-01-01

    One way to combat multidrug-resistant microorganisms is the use of efflux pump inhibitors (EPIs). Spontaneous mutants resistant to the EPI reserpine selected from Streptococcus pneumoniae NCTC 7465 and R6 at a frequency suggestive of a single mutational event were also multidrug resistant. No mutations in pmrA (which encodes the efflux protein PmrA) were detected, and the expression of pmrA was unaltered in all mutants. In the reserpine-resistant multidrug-resistant mutants, the overexpression of both patA and patB, which encode ABC transporters, was associated with accumulation of low concentrations of antibiotics and dyes. The addition of sodium orthovanadate, an inhibitor of ABC efflux pumps, or the insertional inactivation of either gene restored wild-type antibiotic susceptibility and wild-type levels of accumulation. Only when patA was insertionally inactivated were both multidrug resistance and reserpine resistance lost. Strains in which patA was insertionally inactivated grew significantly more slowly than the wild type. These data indicate that the overexpression of both patA and patB confers multidrug resistance in S. pneumoniae but that only patA is involved in reserpine resistance. The selection of reserpine-resistant multidrug-resistant pneumococci has implications for analogous systems in other bacteria or in cancer. PMID:18362193

  11. Activities of a New Fluoroketolide, HMR 3787, and Its (Des)-Fluor Derivative RU 64399 Compared to Those of Telithromycin, Erythromycin A, Azithromycin, Clarithromycin, and Clindamycin against Macrolide-Susceptible or -Resistant Streptococcus pneumoniae and S. pyogenes

    PubMed Central

    Nagai, Kensuke; Davies, Todd A.; Ednie, Lois M.; Bryskier, Andre; Palavecino, Elizabeth; Jacobs, Michael R.; Appelbaum, Peter C.

    2001-01-01

    Activities of HMR 3787 and RU 64399 were compared to those of three macrolides, telithromycin, and clindamycin against 175 Streptococcus pneumoniae isolates and 121 Streptococcus pyogenes isolates. HMR3787 and telithromycin were the most active compounds tested against pneumococci. Telithromycin and RU 64399 were equally active against macrolide-susceptible (MICs, 0.008 to 0.06 μg/ml) and -resistant S. pyogenes isolates, but HMR 3787 had lower MICs for ermB strains. PMID:11600391

  12. Fluoroquinolone Resistance in Streptococcus pneumoniae: Area Under the Concentration-Time Curve/MIC Ratio and Resistance Development with Gatifloxacin, Gemifloxacin, Levofloxacin, and Moxifloxacin▿

    PubMed Central

    LaPlante, Kerry L.; Rybak, Michael J.; Tsuji, Brian; Lodise, Thomas P.; Kaatz, Glenn W.

    2007-01-01

    The potential for resistance development in Streptococcus pneumoniae secondary to exposure to gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin at various levels was examined at high inoculum (108.5 to 109 log10 CFU/ml) over 96 h in an in vitro pharmacodynamic (PD) model using two fluoroquinolone-susceptible isolates. The pharmacokinetics of each drug was simulated to provide a range of free areas under the concentration-time curves (fAUC) that correlated with various fluoroquinolone doses. Potential first (parC and parE)- and second-step (gyrA and gyrB) mutations in isolates with raised MICs were identified by sequence analysis. PD models simulating fAUC/MICs of 51 and ≤60, 34 and 37, ≤82 and ≤86, and ≤24 for gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin, respectively, against each isolate were associated with first-step parC (S52G, S79Y, and N91D) and second-step gyrA (S81Y and S114G) mutations. For each fluoroquinolone a delay of first- and second-step mutations was observed with increasingly higher fAUC/MIC ratios and recovery of topoisomerase mutations in S. pneumoniae was related to the fAUC/MIC exposure. Clinical doses of gatifloxacin, gemifloxacin, and moxifloxacin exceeded the fAUC/MIC resistance breakpoint against wild-type S. pneumoniae, whereas those of levofloxacin (500 and 750 mg) were associated with first- and second-step mutations. The exposure breakpoints for levofloxacin were significantly different (P < 0.001) from those of the newer fluoroquinolones gatifloxacin, gemifloxacin, and moxifloxacin. Additionally, moxifloxacin breakpoints were significantly lower (P < 0.002) than those of gatifloxacin. The order of resistance development determined from fAUC/MIC breakpoints was levofloxacin > gatifloxacin > moxifloxacin = gemifloxacin, which may be related to structural differences within the class. PMID:17296740

  13. Fluoroquinolone resistance in Streptococcus pneumoniae: area under the concentration-time curve/MIC ratio and resistance development with gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin.

    PubMed

    LaPlante, Kerry L; Rybak, Michael J; Tsuji, Brian; Lodise, Thomas P; Kaatz, Glenn W

    2007-04-01

    The potential for resistance development in Streptococcus pneumoniae secondary to exposure to gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin at various levels was examined at high inoculum (10(8.5) to 10(9) log10 CFU/ml) over 96 h in an in vitro pharmacodynamic (PD) model using two fluoroquinolone-susceptible isolates. The pharmacokinetics of each drug was simulated to provide a range of free areas under the concentration-time curves (fAUC) that correlated with various fluoroquinolone doses. Potential first (parC and parE)- and second-step (gyrA and gyrB) mutations in isolates with raised MICs were identified by sequence analysis. PD models simulating fAUC/MICs of 51 andresistance breakpoint against wild-type S. pneumoniae, whereas those of levofloxacin (500 and 750 mg) were associated with first- and second-step mutations. The exposure breakpoints for levofloxacin were significantly different (P<0.001) from those of the newer fluoroquinolones gatifloxacin, gemifloxacin, and moxifloxacin. Additionally, moxifloxacin breakpoints were significantly lower (P<0.002) than those of gatifloxacin. The order of resistance development determined from fAUC/MIC breakpoints was levofloxacin>gatifloxacin>moxifloxacin=gemifloxacin, which may be related to structural differences within the class.

  14. What causes decreased erythromycin resistance in Streptococcus pyogenes? Dynamics of four clones in a southern European region from 2005 to 2012.

    PubMed

    Montes, Milagrosa; Tamayo, Esther; Mojica, Catalina; García-Arenzana, José M; Esnal, Olatz; Pérez-Trallero, Emilio

    2014-06-01

    To survey antibiotic resistance among Streptococcus pyogenes isolates collected from 2005 to 2012, to characterize those showing erythromycin resistance and to analyse the association of certain emm types with erythromycin resistance or susceptibility. Resistance determinants or mutations conferring erythromycin, clindamycin, tetracycline and fluoroquinolone resistance were analysed. All erythromycin-resistant isolates and a sample of erythromycin-susceptible isolates were emm typed. Multilocus sequence typing was performed for representative emm types. Antimicrobial susceptibility was studied for 12 346 S. pyogenes isolates. Erythromycin, clindamycin and tetracycline resistance showed a decreasing trend. In 2012, 2.8% of isolates were erythromycin resistant versus 7.5% in 2005 and 11.7% in 2006. Although 21 clones were involved, 4 clones accounted for almost 90% of erythromycin-resistant isolates. The emm12/ST36 clone, carrying the mef(A) gene, was the predominant (41.1%) erythromycin-resistant clone, with an incidence peak in 2008, followed by a gradual decline. The M phenotype predominated each year except for 2005, when two of the main erythromycin-resistant clones (emm11/ST403 and emm28/ST52) harboured an erm(B) gene. Erythromycin resistance was significantly higher in adults than in children. Skin isolates showed the highest erythromycin resistance rate; among these, perianal isolates frequently belonged to the emm28/ST52 clone. The emm type was not a predictor of erythromycin resistance; however, most emm11 and emm12 were erythromycin-resistant isolates. Macrolide consumption was similar throughout the study period. Only two isolates with a high level of levofloxacin resistance were detected. Resistance was mainly related to the circulation of emm12/ST36, emm11/ST403, emm28/ST52 and emm4/ST39 clones, all of which declined throughout the study period. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial

  15. Antibiotic resistance of Streptococcus pneumoniae colonising the nasopharynx of HIV-exposed Tanzanian infants.

    PubMed

    Bles, P; de Mast, Q; van der Gaast-de Jongh, C E; Kinabo, G D; Kibiki, G; van de Ven, A; de Jonge, M I

    2015-11-01

    To determine antibiotic susceptibility of colonising pneumococcal serotypes in HIV-exposed infants before the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13), because HIV-exposed infants are at increased risk of invasive pneumococcal infections. Antibiotic susceptibility of 104 pneumococcal isolates, cultured from the nasopharynx from Tanzanian HIV-exposed infants, was determined using the disc diffusion method and the E-test according to EUCAST version 4.0 (2014) criteria. A total of 69.2% of isolates were intermediately susceptible for benzyl penicillin (MIC 0.06-2 mg/l ); no high-level resistance was found. All isolates but one were susceptible to ampicillin. Regarding non-beta-lactam antibiotics, 19.2% of isolates were resistant to doxycycline, 3.8% to erythromycin and 97.1% to trimethoprim/sulfamethoxazole. A total of 15.4% of isolates were resistant to three antibiotic classes or more. There were no differences in antibiotic susceptibility between vaccine and non-vaccine serotypes. Reduced susceptibility of colonising pneumococcal isolates for commonly used antibiotics is common in HIV-exposed Tanzanian infants. High-dose penicillin and ampicillin remain appropriate first choices for non-meningeal pneumococcal infections in this group. © 2015 John Wiley & Sons Ltd.

  16. Serotypes, antimicrobial resistance and genotypes of Streptococcus pneumoniae associated with infections in cancer patients in Brazil.

    PubMed

    Cardoso, Nayara Torres; Santos, Bárbara Araújo; Barbosa, André Victor; Superti, Silvana Vargas; Teixeira, Lúcia Martins; Neves, Felipe Piedade Gonçalves

    2017-03-01

    We sought to characterize pneumococcal isolates associated with bacteremia, pneumonia and meningitis in cancer patients and to estimate the coverage of the available pneumococcal vaccines. Fifty isolates recovered from 49 patients attending a cancer reference center over a 1-year period were analyzed. The prevalent serotypes were: 23F (12%), 6A (8%), 3, 4, 20, and 23A (6% each). All isolates were susceptible to chloramphenicol, levofloxacin, rifampicin, and vancomycin. Resistance or reduced susceptibility to penicillin made up 14%, and one isolate was also intermediately resistant to ceftriaxone. The three (6%) erythromycin-resistant isolates presented the M or cMLSB phenotypes and harbored the mef(A/E) gene exclusively or along with the erm(B) gene. Twenty-two (44%) isolates were closely related to 11 international clones, being strongly associated with penicillin non-susceptibility. Combined immunization with the 13-valent conjugate and the 23-valent polysaccharide vaccines might contribute to reduce (76%) the burden of the pneumococcal infections in the population investigated.

  17. Fluoroquinolone resistance of Streptococcus pneumoniae isolates causing invasive disease: special focus on zabofloxacin.

    PubMed

    Kim, Tark; Park, Su-Jin; Chong, Yong Pil; Park, Ki-Ho; Lee, Yu-Mi; Hong, Hyo-Lim; Kim, Hee Seung; Kim, Eun Sil; Lee, Sungkyoung; Choi, Dong Rack; Kim, Sung-Han; Jeong, Jin-Yong; Lee, Sang-Oh; Choi, Sang-Ho; Woo, Jun Hee; Kim, Yang Soo

    2016-10-01

    The present study examined the in vitro activity of various antibiotics including zabofloxacin, against isolates responsible for invasive pneumococcal diseases. Between 1997 and 2008, a total of 208 isolates were collected from sterile fluids, including blood (n=196, 94.2%), pleural fluid (n=5, 2.4%), cerebrospinal fluid (n=5, 2.4%), and ascites (n=2, 1.0%). Zabofloxacin showed the lowest MIC50 (0.015μg/mL) and MIC90 (0.025μg/mL) values of all the tested antibiotics. Rates of isolates resistant to penicillin (MIC ≥8μg/mL), ceftriaxone (MIC ≥4μg/mL) and levofloxacin (MIC ≥8μg/mL) were 3.4%, 0.4% and 2.0%, respectively. Four isolates (2.0%) were resistant to levofloxacin, and zabofloxacin showed low MICs (range, 0.025-0.125μg/mL). Zabofloxacin shows potent in vitro activity against S. pneumoniae isolates that caused invasive disease, even strains that are resistant to levofloxacin.

  18. Streptococcus pneumoniae nasopharyngeal carriage prevalence, serotype distribution, and resistance patterns among children on Lombok Island, Indonesia.

    PubMed

    Soewignjo, S; Gessner, B D; Sutanto, A; Steinhoff, M; Prijanto, M; Nelson, C; Widjaya, A; Arjoso, S

    2001-04-01

    Few data exist on childhood pneumococcal carriage prevalence, serotype distribution, and resistance patterns for Indonesia, the world's fourth most populous country. During August 1997, nasopharyngeal samples were collected from a population-based, island-wide sample of 484 healthy children (age, 0-25 months) from Lombok Island, Indonesia. Two hundred twenty-one pneumococcal isolates were identified, for a carriage prevalence of 48%; 66% of isolates were of serogroup or serotype 6, 23, 15, 33, or 12. All isolates were susceptible to penicillin and cefotaxime. Twelve percent of the isolates were nonsusceptible to sulfamethoxazole or chloramphenicol and 4% were nonsusceptible to both of these drugs. Nonsusceptible organisms were most frequently serogroup or serotype 6, 12, and 33. Lombok has a moderate pneumococcal carriage prevalence and a relatively low proportion of resistant isolates. At least 3 of the 5 most common serogroups and serotypes and 2 of the 3 most common nonsusceptible serogroups and serotypes are not included in the current 7-valent pneumococcal conjugate vaccine.

  19. Surveillance of antibiotic resistance in non invasive clinical isolates of Streptococcus pneumoniae collected in Belgium during winters 2003 and 2004.

    PubMed

    Vanhoof, R; Carpentier, M; Cartuyvels, R; Damée, S; Fagnart, O; Frans, J; Gordts, B; Glupczynski, Y; Goffinet, P; Govaerts, D; Lefèvre, P h; Lontie, M; Magerman, K; Mans, I; Meunierz, F; Moonens, F; Surmont, I; Van Bossuyt, E; Van De Vyvere, M; Van Eldere, J; Van Landuyt, H; Van Nimmen, L; Van Noyen, R; Verhaegen, J

    2006-01-01

    A total of 391 and 424 non-invasive isolates of Streptococcus pneumoniae collected by 15 laboratories during the 2003 and 2004 survey were tested for their susceptibility by a microdilution technique following NCCLS recommendations. Insusceptibility rates (IR) in the two surveys (2003/2004) were as follows: penicillin 15.0/14.7% [8.4/6.4% Resistance (R)], ampicillin 17.4/14.6% (R 9.0/7.1%), amoxicillin +/- clavulanic acid 2.6/1.2 % (R 0/0%), cefaclor 14.3/14.1% (R 11.5/13.4%), cefuroxime 13.6/12.7% (R 10.5/11.8%), cefuroxime-axetil 10.5/11.8% (R 10.0/9.2%) (breakpoints based on 250 mg), cefotaxime 4.9/6.2% (R 1.3/2.4%), ceftazidime NotTested (NT)/6.4 (R NT/2.6%), cefepime NT/6.4 (R NT/2.6%), imipenem 7.7/8.9 % (R 1.8/1.4%), ertapenem 0.8/NT% (R O/NT%), ciprofloxacin 13.8/9.0% (R 4.3/2.4%), levofloxacin 3.3/2.8% (R 1.5/0.2%), moxifloxacin 0.6/0.2% (R 0.3/0%), ofloxacin 13.5/9.0% (R 4.3/2.4%), erythromycin 26.1/24.7% (R 25.3/24.5%), azithromycin 25.4/24.7% (R 24.6/24.5%), telithromycin 0.8/0.2% (R 0.5/0%), clindamycin 21.2/18.4% (R 19.2/17.7%) and tetracycline 32.3/22.1% (R 29.2/19.3%). There were only minor differences in resistance rates according to age, sample site, admission type (i.e. ambulatory, hospitalized or long-term care facility patients), gender and geographic origin. Overall, telithromycin (MIC50, MIC90 in 2003/2004: 0.015 microg/ml, 0.12 microg/ml/ 0.008,0.06 respectively), ertapenem (0.03; 0.25/NT), moxifloxacin (0.06; 0.25/0.06, 0.12), and amoxicillin +/- clavulanic acid (0.03; 0.25/0.015, 0.5) were the most active compounds in both surveys. In 2003, the most common resistance phenotype was isolated insusceptibility to tetracycline (10.5%) followed by combined insusceptibility to erythromycin and tetracycline (9.3%). Erythromycin-tetracycline resistance (10.4%) was the most common in 2004. Isolates showing resistance to an antibiotic were significantly more present in 2003 than in 2004 (50.4% versus 40.8%). In penicillin-insusceptible isolates, MICs

  20. Artemin promotes oncogenicity, metastasis and drug resistance in cancer cells.

    PubMed

    Hezam, Kamal; Jiang, Jiahao; Sun, Fumou; Zhang, Xinrong; Zhang, Juan

    2017-09-22

    Artemin (ARTN) is a member of glial cell line-derived neurotrophic factor (GDNF) family of ligands, and its signaling is mediated via a multi-component receptor complex including the glycosylphosphatidylinositol-anchored GDNF family receptors a (GFRa1, GFRa3) and RET receptor tyrosine kinase. The major mechanism of ARTN action is via binding to a non-signaling co-receptor. The major function of ARTN is to drive the molecule to induce migration and axonal projection from sympathetic neurons. It also promotes the survival, proliferation and neurite outgrowth of sympathetic neurons in vitro. ARTN triggers oncogenicity and metastasis by the activation of the AKT signaling pathway. Recent studies have reported that the expression of ARTN in hepatocellular carcinoma is associated with increased tumor size, quick relapse and shorter survival. Furthermore, ARTN promotes drug resistance such as antiestrogens, doxorubicin, fulvestrant, paclitaxel, tamoxifen and trastuzumab. Moreover, ARTN also stimulates the radio-therapeutic resistance. This review highlights the proposed roles of ARTN in cancer cells and discusses recent results supporting its emerging role as an oncogenic, metastatic and drug-resisting agent with a special focus on how these new insights may facilitate rational development of ARTN for targeted therapies in the future.

  1. Sequence Elements Upstream of the Core Promoter Are Necessary for Full Transcription of the Capsule Gene Operon in Streptococcus pneumoniae Strain D39

    PubMed Central

    Wen, Zhensong; Sertil, Odeniel; Cheng, Yongxin; Zhang, Shanshan; Liu, Xue; Wang, Wen-Ching

    2015-01-01

    Streptococcus pneumoniae is a major bacterial pathogen in humans. Its polysaccharide capsule is a key virulence factor that promotes bacterial evasion of human phagocytic killing. While S. pneumoniae produces at least 94 antigenically different types of capsule, the genes for biosynthesis of almost all capsular types are arranged in the same locus. The transcription of the capsular polysaccharide (cps) locus is not well understood. This study determined the transcriptional features of the cps locus in the type 2 virulent strain D39. The initial analysis revealed that the cps genes are cotranscribed from a major transcription start site at the −25 nucleotide (G) upstream of cps2A, the first gene in the locus. Using unmarked chromosomal truncations and a luciferase-based transcriptional reporter, we showed that the full transcription of the cps genes not only depends on the core promoter immediately upstream of cps2A, but also requires additional elements upstream of the core promoter, particularly a 59-bp sequence immediately upstream of the core promoter. Unmarked deletions of these promoter elements in the D39 genome also led to significant reduction in CPS production and virulence in mice. Lastly, common cps gene (cps2ABCD) mutants did not show significant abnormality in cps transcription, although they produced significantly less CPS, indicating that the CpsABCD proteins are involved in the encapsulation of S. pneumoniae in a posttranscriptional manner. This study has yielded important information on the transcriptional characteristics of the cps locus in S. pneumoniae. PMID:25733517

  2. [Evolution of the antibiotic resistance of Streptococcus pneumoniae from 1997 to 2004 at Hôtel-Dieu de France, a university hospital in Lebanon].

    PubMed

    Karam Sarkis, D; Hajj, A; Adaimé, A

    2006-12-01

    Various rates of Streptococcus pneumoniae with diminished susceptibility to Penicillin G (PNSP) are reported worldwide, while resistance to cefotaxime and ceftriaxone is actually increasing among S. pneumoniae. The aim of this survey was to determine the evolution of the susceptibility and resistance of S. pneumoniae at our hospital, throughout the years 1997-2004. 582 S. pneumoniae strains, isolated from different patients with pulmonary disease, otitis media, bacteremia and/or meningitis have been observed. MIC to benzylpenicillin (P), ampicillin (AMP) and ceftriaxone (CRO) were determined by E-TEST. Susceptibility to erythromycin (ERY), cotrimoxazole (SXT), tetracycline (TE) and rifampicin (RA) were determined by agar diffusion. All tests were interpreted according to CA-SFM guidelines. The percentage of PNSP varied between 49.6 and 69%. S. pneumoniae with reduced susceptibility to benzylpenicillin had stable rates, while fully resistant S. pneumoniae decreased significantly. Resistance to ampicillin varied alongside with penicillin with a decrease of fully resistant S. pneumoniae. Strains intermediate to ceftriaxone also decreased significantly while those fully resistant were not detected, except for 1999 (1 strain). The resistance (I+R) to SXT and TE remained stable with small variations, but resistance to ERY increased up to 43% of isolated strains in 2004. Resistance to LVX and RA was absent, with unexpected levels for RA (1 and 5%) in 2002 and 2003.

  3. Activities of garenoxacin against quinolone-resistant Streptococcus pneumoniae strains in vitro and in a mouse pneumonia model.

    PubMed

    Azoulay-Dupuis, E; Bédos, J P; Mohler, J; Peytavin, G; Isturiz, R; Moine, P; Rieux, V; Cherbuliez, C; Péchère, J C; Fantin, B; Köhler, T

    2004-03-01

    Garenoxacin is a novel des-F(6) quinolone with enhanced in vitro activities against both gram-positive and gram-negative bacteria. We compared the activity of garenoxacin with that of trovafloxacin (TVA) against Streptococcus pneumoniae, together with their efficacies and their capacities to select for resistant mutants, in a mouse model of acute pneumonia. In vitro, garenoxacin was more potent than TVA against wild-type S. pneumoniae and against a mutant with a single mutation (parC), a mutant with double mutations (gyrA and parC), and a mutant with triple mutations (gyrA, parC, and parE). Swiss mice were infected with 10(5) CFU of virulent, encapsulated S. pneumoniae strain P-4241 or its derived isogenic parC, gyrA, gyrA parC, and efflux mutants and 10(7) CFU of poorly virulent clinical strains carrying a parE mutation or gyrA, parC, and parE mutations. The drugs were administered six times, every 12 h, beginning at either 3 or 18 h postinfection. The pulmonary pharmacokinetic parameters in mice infected with strain P-4241 and treated with garenoxacin or TVA (25 mg/kg of body weight) were as follows: maximum concentration of drug in serum (C(max); 17.3 and 21.2 micro g/ml, respectively), C(max)/MIC ratio (288 and 170, respectively), area under the concentration-time curve (AUC; 48.5 and 250 microg. h/ml, respectively), and AUC/MIC ratio (808 and 2000, respectively). Garenoxacin at 25 and 50 mg/kg was highly effective (survival rates, 85 to 100%) against the wild-type strain and mutants harboring a single mutation. TVA was as effective as garenoxacin against these strains. TVA at 200 mg/kg and garenoxacin at 50 mg/kg were ineffective against the mutant with the parC and gyrA double mutations and the mutant with the gyrA, parC, and parE triple mutations. The efficacy of garenoxacin was reduced only when strains bore several mutations for quinolone resistance.

  4. Interactive resistance chair to promote strengthening exercise in older adults.

    PubMed

    Jeong, In Cheol; Finkelstein, Joseph

    2015-01-01

    We developed a strengthening exercise support system which can be remotely managed and clinically supervised via internet. Older adults may potentially benefit from such an exercise system however functionality of this system requires validation before commencement of field studies in older adults. The aim of this study was to introduce and assess validity of a prototype telerehabilitation system supporting computer-assisted home-based strengthening exercise. The system included a resistance chair with a set of movement and physiologic sensors. Real-time feedback on exercise performance was displayed on a touch screen dashboard. Personalized exercise parameters were managed by a rehabilitation team via a designated telerehabilitation site. Assessment of the system demonstrated sufficient validity in real-time identification of exercise performance and cardiovascular parameters. We concluded that the interactive resistance chair has a potential in promoting strengthening exercise and it is warranted for further evaluation in community dwelling older adults.

  5. In Vitro Activity of the New Ketolide Telithromycin Compared with Those of Macrolides against Streptococcus pyogenes: Influences of Resistance Mechanisms and Methodological Factors

    PubMed Central

    Bemer-Melchior, Pascale; Juvin, Marie-Emmanuelle; Tassin, Sandrine; Bryskier, Andre; Schito, Gian Carlo; Drugeon, Henri-B.

    2000-01-01

    One hundred and seven clinical isolates of Streptococcus pyogenes, 80 susceptible to macrolides and 27 resistant to erythromycin A (MIC >0.5 μg/ml), were examined. The erythromycin A-lincomycin double-disk test assigned 7 resistant strains to the M-phenotype, 8 to the inducible macrolide, lincosamide, and streptogramin B resistance (iMLSB) phenotype, and 12 to the constitutive MLSB resistance (cMLSB) phenotype. MICs of erythromycin A, clarithromycin, azithromycin, roxithromycin, and clindamycin were determined by a broth microdilution method. MICs of telithromycin were determined by three different methods (broth microdilution, agar dilution, and E-test methods) in an ambient air atmosphere and in a 5 to 6% CO2 atmosphere. Erythromycin A resistance genes were investigated by PCR in the 27 erythromycin A-resistant isolates. MICs of erythromycin A and clindamycin showed six groups of resistant strains, groups A to F. iMLSB strains (A, B, and D groups) are characterized by two distinct patterns of resistance correlated with genotypic results. A- and B-group strains were moderately resistant to 14- and 15-membered ring macrolides and highly susceptible to telithromycin. All A- and B-group isolates harbored erm TR gene, D-group strains, highly resistant to macrolides and intermediately resistant to telithromycin (MICs, 1 to 16 μg/ml), were all characterized by having the ermB gene. All M-phenotype isolates (C group), resistant to 14- and 15-membered ring macrolides and susceptible to clindamycin and telithromycin, harbored the mefA gene. All cMLSB strains (E and F groups) with high level of resistance to macrolides, lincosamide, and telithromycin had the ermB gene. The effect of 5 to 6% CO2 was remarkable on resistant strains, by increasing MICs of telithromycin from 1 to 6 twofold dilutions against D-E- and F-group isolates. PMID:11036012

  6. Frequency of mutation to rifampin resistance in Streptococcus pneumoniae clinical strains: hexA and hexB polymorphisms do not account for hypermutation.

    PubMed

    Morosini, María-Isabel; Baquero, María-Rosario; Sánchez-Romero, J M; Negri, María-Cristina; Galán, Juan-Carlos; del Campo, Rosa; Pérez-Díaz, J C; Baquero, Fernando

    2003-04-01

    The frequency of mutation to rifampin resistance of 200 clinical Streptococcus pneumoniae isolates was examined. Two peaks were observed in the distribution, with mode frequencies of 2.5 x 10(-7) (20% of isolates) and 2.5 x 10(-8). The hexA and hexB gene entire sequences were analyzed in 13 isolates. Sequences from both hypermutable and "normomutable" strains were conserved relative to that of the R6 S. pneumoniae control strain. The phenotypic Hex system proficiency, in terms of transforming efficiency, was also maintained irrespective of the variations in mutation frequency values.

  7. In Vitro Activity of Lefamulin Tested against Streptococcus pneumoniae with Defined Serotypes, Including Multidrug-Resistant Isolates Causing Lower Respiratory Tract Infections in the United States

    PubMed Central

    Farrell, David J.; Flamm, Robert K.; Talbot, George H.; Ivezic-Schoenfeld, Zrinka; Paukner, Susanne; Sader, Helio S.

    2016-01-01

    Lefamulin was evaluated against various Streptococcus pneumoniae serotypes that were collected from adults with lower respiratory tract infections. Lefamulin exhibited MIC50 and MIC90 values of 0.12 and 0.25 μg/ml, respectively, against the entire collection (n = 822). Similar results were obtained for lefamulin against each of the most common serotypes as well as against multidrug-resistant isolates and strains that are nonsusceptible to ceftriaxone or erythromycin. These data support the clinical development of lefamulin for the treatment of community-acquired respiratory tract infections. PMID:27161634

  8. Susceptibility to new beta-lactams of enterobacterial extended-spectrum beta-lactamase (ESBL) producers and penicillin-resistant Streptococcus pneumoniae in Mexico.

    PubMed

    Silva, J; Aguilar, C; Estrada, M A; Echániz, G; Carnalla, N; Soto, A; López-Antuñano, F J

    1998-04-01

    The activities of several beta-lactam antimicrobial agents, aminoglycosides and ciprofloxacin, were determined against 62 clinical isolates of enterobacteria resistant to oxyimino cephalosporins (extended-spectrum beta-lactamase producers), collected during 1991 to 1993, and 16 penicillin-resistant invasive isolates of Streptococcus pneumoniae collected during 1994-1996. The numbers and percentages of susceptible enterobacterial strains to tested antibiotics were: imipenem 60 (97%), ciprofloxacin 57 (92%), cefepime 56 (90%), cefpirome 34 (55%), aztreonam 13 (21%), cefotaxime 7 (11%), ceftazidime 0 (0%), amikacin 11 (18%) and gentamicin 16 (26%). Despite the fact that these strains had never been exposed previously to cefepime or cefpirome, the susceptibility was 90% and 55%, respectively. No penicillin-resistant strains of S. pneumoniae were susceptible to cefotaxime, imipenem or cefepime. Only one strain was susceptible to ceftazidime and 4 (25%) were susceptible to cefpirome. Erythromycin showed the greatest activity with 12 (75%) susceptible strains.

  9. Additive genetic variation in resistance of Nile tilapia (Oreochromis niloticus) to Streptococcus iniae and S. agalactiae capsular type Ib: is genetic resistance correlated?

    USDA-ARS?s Scientific Manuscript database

    Streptococcus (S.) iniae and S. agalactiae are both economically important Gram positive bacterial pathogens affecting the globally farmed tilapia (Oreochromis spp.). Historically control of these bacteria in tilapia culture has included biosecurity, therapeutants and vaccination strategies. Genet...

  10. Macrolide-resistance mechanisms in Streptococcus pneumoniae isolates from Chinese children in association with genes of tetM and integrase of conjugative transposons 1545.

    PubMed

    Shen, Xuzhuang; Yang, Hui; Yu, Shangjie; Yao, Kaihu; Wang, Yonghong; Yuan, Lin; Yang, Yonghong

    2008-06-01

    This study investigated macrolide-resistant Streptococcus pneumoniae carried by Beijing children presenting with respiratory tract infections. Nasopharyngeal S. pneumoniae strains were tested for sensitivity with 15 antibiotics and further analyzed for phenotypes of macrolide-resistant strains and by PCR for the macrolide-resistant genes ermB, mefA, tetM, and integrase of conjugative transposon (Tn1545) intTn. We found 185 strains of S. pneumoniae relatively highly resistant to erythromycin (78.9%), clindamycin (76.2%), tetracycline (86%), and SMZ-TMP (78.7%) but with relatively low resistance to amoxicillin (2.2%), cefaclor (15.5%), ceftriaxone (2.8%), and cefuroxime (14.1%). The 146 strains of erythromycin-resistant S. pneumoniae showed extensive cross-resistance to other macrolides like azithromycin (100%), clarithromycin (100%), acetylspiramycin (95.2%), and clindamycin (95.9%). Genes ermB and mefA were detected in all erythromycin-resistant strains, with ermB(+) 79.5%, ermB + mefA(+) 17.8%, and mefA(+) 2.7%. About 96.9% of tetracycline-resistant isolates were positive for tetM, compared to 26.9% of sensitive strains. Ninety percent of tetracycline-resistant strains were also erythromycin-resistant versus 11.5% of tetracycline-sensitive strains. The intTn gene was present in 87.6% of S. pneumoniae strains and correlated with erythromycin and tetracycline resistance. The close relationship between the conjugative transposon Tn1545 and the genes ermB and tetM is probably one of the important mechanisms explaining the multiple drug resistance of S. pneumoniae.

  11. Nasopharyngeal carriage of multidrug-resistant Streptococcus pneumoniae in institutionalized HIV-infected and HIV-negative children in northeastern Romania.

    PubMed

    Leibovitz, E; Dragomir, C; Sfartz, S; Porat, N; Yagupsky, P; Jica, S; Florescu, L; Dagan, R

    1999-01-01

    The study compared nasopharyngeal carriage of resistant pneumoniae in human immunodeficiency virus (HIV)-seropositive and -seronegative children. Nasopharyngeal colonization with Streptococcus pneumoniae was investigated during May 1996 in 162 HIV-negative infants and children (age range, 1-38 mo) and 40 HIV-infected children (age range, 39-106 mo) living in an orphanage in Iasi, northeastern Romania. The HIV-infected children lived separated from the other children and were cared for by a different staff. Streptococcus pneumoniae was isolated from 12 of 40 (30%) HIV-infected and from 81 of 160 (50%) HIV-negative children. Antimicrobial susceptibility to penicillin and ceftriaxone was determined by E-test, and to another five antibiotics by disk diffusion. Serotyping was performed by the Quellung method on 81 of 93 (87%) isolates. Serotypes 6A, 6B, 19A, and 23F together represented 98% of all isolates. Ninety-nine percent of S. pneumoniae isolates were resistant to penicillin, and 74% were highly resistant to penicillin (minimum inhibitory concentration [MIC] > 1 mg/mL); MIC50 and MIC90 to penicillin of the isolates were 2 mg/mL and 8 mg/mL, respectively. Eighty-nine of ninety-one isolates were susceptible to ceftriaxone; 99%, 87%, 87%, 48%, and 21% of the isolates were resistant to trimethoprim-sulphamethoxazole, erythromycin, clindamycin, tetracycline, and chloramphenicol, respectively. Eighty-two (89%) isolates were multidrug resistant (resistant to =/>3 antibiotic classes); 37 of 92 (40%) isolates were resistant to 5 or more antibiotic classes, and 16 of these 37 (43%) belonged to serotype 19A. All serotype 19 isolates were highly resistant to penicillin. No significant differences were observed in the resistance rates of S. pneumoniae in HIV-infected children compared to HIV-negative children. Multidrug-resistant pneumococci were highly prevalent in this Romanian orphanage in both HIV-negative and older HIV-infected children. The observed high prevalence of

  12. Termites promote resistance of decomposition to spatiotemporal variability in rainfall.

    PubMed

    Veldhuis, Michiel P; Laso, Francisco J; Olff, Han; Berg, Matty P

    2017-02-01

    The ecological impact of rapid environmental change will depend on the resistance of key ecosystems processes, which may be promoted by species that exert strong control over local environmental conditions. Recent theoretical work suggests that macrodetritivores increase the resistance of African savanna ecosystems to changing climatic conditions, but experimental evidence is lacking. We examined the effect of large fungus-growing termites and other non-fungus-growing macrodetritivores on decomposition rates empirically with strong spatiotemporal variability in rainfall and temperature. Non-fungus-growing larger macrodetritivores (earthworms, woodlice, millipedes) promoted decomposition rates relative to microbes and small soil fauna (+34%) but both groups reduced their activities with decreasing rainfall. However, fungus-growing termites increased decomposition rates strongest (+123%) under the most water-limited conditions, making overall decomposition rates mostly independent from rainfall. We conclude that fungus-growing termites are of special importance in decoupling decomposition rates from spatiotemporal variability in rainfall due to the buffered environment they create within their extended phenotype (mounds), that allows decomposition to continue when abiotic conditions outside are less favorable. This points at a wider class of possibly important ecological processes, where soil-plant-animal interactions decouple ecosystem processes from large-scale climatic gradients. This may strongly alter predictions from current climate change models.

  13. Variable resistance training promotes greater fatigue resistance but not hypertrophy versus constant resistance training.

    PubMed

    Walker, Simon; Hulmi, Juha J; Wernbom, Mathias; Nyman, Kai; Kraemer, William J; Ahtiainen, Juha P; Häkkinen, Keijo

    2013-09-01

    Loading using variable resistance devices, where the external resistance changes in line with the force:angle relationship, has been shown to cause greater acute neuromuscular fatigue and larger serum hormone responses. This may indicate a greater potential for adaptation during long-term training. Twelve (constant resistance group) and 11 (variable resistance group) men completed 20 weeks of resistance training with 10 men as non-training controls. Training-induced adaptations were assessed by bilateral leg press one repetition maximum, a repetition to failure test using 75 % 1RM, lower limb lean mass and vastus lateralis cross-sectional area. Only the variable resistance training group improved the total number of repetitions (41 ± 46 %) and volume load (52 ± 37 %) during the repetition to failure test (P < 0.05). Similar improvements in maximum strength and hypertrophy of the lower limbs were observed in both training groups. Also, constant and variable resistance 5 × 10RM leg press loadings were performed before and after training in a crossover design. Acute loading-induced responses were assessed by concentric and isometric force, serum hormone concentrations and phosphorylation of intramuscular signalling proteins (0-30 min post-loading). Greater acute decreases in force (P < 0.05-0.01), and greater increases in serum testosterone and cortisol concentration (P < 0.05) and ERK 1/2 phosphorylation (P < 0.05) were observed following variable resistance loadings before and after training. Greater training-induced improvements in fatigue resistance occurred in the variable resistance training group, which may be due to greater acute fatigue and physiological responses during variable versus constant resistance loadings.

  14. Emergence of quinolone-resistant strains in Streptococcus pneumoniae isolated from paediatric patients since the approval of oral fluoroquinolones in Japan.

    PubMed

    Takeuchi, Noriko; Ohkusu, Misako; Hoshino, Tadashi; Naito, Sachiko; Takaya, Akiko; Yamamoto, Tomoko; Ishiwada, Naruhiko

    2017-01-31

    Tosufloxacin (TFLX) is a fluoroquinolone antimicrobial agent. TFLX granules for children were initially released in Japan in 2010 to treat otitis media and pneumonia caused by drug-resistant bacteria, e.g. penicillin-resistant Streptococcus pneumoniae and beta-lactamase-negative, ampicillin-resistant Haemophilus influenzae. The evolution of bacterial resistance since TFLX approval is not known. To clarify the influence of quinolones administered to children since their approval, we examined the resistance mechanism of TFLX-resistant S. pneumoniae isolated from paediatric patients as well as patient clinical characteristics. TFLX-resistant strains (MIC ≥ 2 mg/L) were detected among clinical isolates of S. pneumoniae derived from children (≤15 years old) between 2010 and 2014. These strains were characterised based on quinolone resistance-determining regions (QRDRs), i.e. gyrA, gyrB, parC, and parE. In addition, the antimicrobial susceptibility, serotype, and multilocus sequence type of strains were determined, pulsed-field gel electrophoresis was performed, and patient clinical characteristics based on medical records were assessed for cases with underling TFLX-resistant strains. Among 1168 S. pneumoniae isolates, two TFLX-resistant strains were detected from respiratory specimens obtained from paediatric patients with frequent exposure to TFLX. Both strains had mutations in the QRDRs of gyrA and parC. One case exhibited gradual changes in the QRDR during the clinical course. This is the first study of quinolone-resistant S. pneumoniae isolated from children, including clinical data, in Japan. These data may help prevent increases in infections of quinolone-resistant S. pneumoniae in children; specifically, the results emphasise the importance of administering fluoroquinolones only in appropriate cases.

  15. Mechanism of Fluoroquinolone Resistance Is an Important Factor in Determining the Antimicrobial Effect of Gemifloxacin against Streptococcus pneumoniae in an In Vitro Pharmacokinetic Model

    PubMed Central

    MacGowan, Alasdair P.; Bowker, Karen E.

    2003-01-01

    Antibacterial effect and emergence of resistance to gemifloxacin and levofloxacin were studied in an in vitro pharmacokinetic model of infection. A panel of Streptococcus pneumoniae strains with known mechanisms of resistance were used; two strains had no known resistance mechanism, two had efflux pumps, three had gyrA plus parC mutations, and one had only a parC mutation. Gemifloxacin MICs were in the range of 0.016 to 0.25 mg/liter, and levofloxacin MICs ranged from 1 to 16 mg/liter. Antimicrobial effect was measured by area under the bacterial-kill curve up to 72 h, and emergence of resistance was determined by population analysis profile before and during drug exposure. The area under the curve (AUC)/MIC ratios for gemifloxacin and levofloxacin were 35 to 544 and 3 to 48, respectively. As expected on the basis of these AUC/MIC ratio differences, antibacterial effect was much greater for gemifloxacin than levofloxacin. In the gemifloxacin simulations, mechanism of resistance as well as MIC determined the antibacterial effect, as indicated by gemifloxacin’s greater effect against efflux strains compared to those with gyrA or parC mutations despite similar MICs. This was not true of levofloxacin. Emergence of resistance was not easily demonstrated with either agent, and mechanism of resistance did not have any impact on it. PMID:12604547

  16. Biological and Epidemiological Features of Antibiotic-Resistant Streptococcus pneumoniae in Pre- and Post-Conjugate Vaccine Eras: a United States Perspective

    PubMed Central

    Kim, Lindsay; McGee, Lesley; Tomczyk, Sara

    2016-01-01

    SUMMARY Streptococcus pneumoniae inflicts a huge disease burden as the leading cause of community-acquired pneumonia and meningitis. Soon after mainstream antibiotic usage, multiresistant pneumococcal clones emerged and disseminated worldwide. Resistant clones are generated through adaptation to antibiotic pressures imposed while naturally residing within the human upper respiratory tract. Here, a huge array of related commensal streptococcal strains transfers core genomic and accessory resistance determinants to the highly transformable pneumococcus. β-Lactam resistance is the hallmark of pneumococcal adaptability, requiring multiple independent recombination events that are traceable to nonpneumococcal origins and stably perpetuated in multiresistant clonal complexes. Pneumococcal strains with elevated MICs of β-lactams are most often resistant to additional antibiotics. Basic underlying mechanisms of most pneumococcal resistances have been identified, although new insights that increase our understanding are continually provided. Although all pneumococcal infections can be successfully treated with antibiotics, the available choices are limited for some strains. Invasive pneumococcal disease data compiled during 1998 to 2013 through the population-based Active Bacterial Core surveillance program (U.S. population base of 30,600,000) demonstrate that targeting prevalent capsular serotypes with conjugate vaccines (7-valent and 13-valent vaccines implemented in 2000 and 2010, respectively) is extremely effective in reducing resistant infections. Nonetheless, resistant non-vaccine-serotype clones continue to emerge and expand. PMID:27076637

  17. Resistance of Nile tilapia (Oreochromis niloticus) to Streptococcus iniae and S. agalatiae Ib is heritable but not correlated

    USDA-ARS?s Scientific Manuscript database

    Tilapia (Oreochromis sp.) are an important source of protein with an ecomonic value approaching US $8 billion yearly. Streptococcal disease, caused by Streptococcus iniae and S. agalactiae (both Gram positive bacteria), is an emerging or re-emerging disease negatively affecting tilapia aquaculture w...

  18. Reduction of saliva-promoted adhesion of Streptococcus mutans MT8148 and dental biofilm development by tragacanth gum and yeast-derived phosphomannan.

    PubMed

    Shimotoyodome, A; Kobayashi, H; Nakamura, J; Tokimitsu, I; Hase, T; Inoue, T; Matsukubo, T; Takaesu, Y

    2006-01-01

    The aim of this study was to investigate materials which reduce saliva-promoted adhesion of Streptococcus mutans onto enamel surfaces, and their potential in preventing dental biofilm development. The effects of hydroxyapatite (HA) surface pretreatment with hydrophilic polysaccharides on saliva-promoted S. mutans adhesion in vitro and de novo dental biofilm deposition in vivo were examined. Saliva-promoted adhesion of S. mutans MT8148 was significantly reduced by pretreatment of the HA surface with tragacanth gum (TG) and yeast-derived phosphoglycans. Extracellular phosphomannan (PM) from Pichia capsulata NRRL Y-1842 and TG reduced biofilm development on lower incisors in plaque-susceptible rats when administered via drinking water at concentrations of 0.5% and 0.01%, respectively. The inhibitory effect of TG on de novo dental biofilm formation was also demonstrated when administered via mouthwash in humans. It is concluded that TG and yeast-derived PM have the potential for use as anti-adherent agents and are effective in reducing de novo dental biofilm formation.

  19. The promoter of the operon encoding the F0F1 ATPase of Streptococcus pneumoniae is inducible by pH.

    PubMed

    Martín-Galiano, A J; Ferrándiz, M J; de la Campa, A G

    2001-09-01

    The genes encoding the subunits of the F0F1 membrane ATPase of Streptococcus pneumoniae were cloned and sequenced. The eight genes, transcribed to one mRNA, are organized in an operon encoding the c, a, b, delta, alpha, gamma, beta and epsilon subunits of 66, 238, 165, 178, 501, 292, 471 and 139 amino acid residues, respectively, that were expressed in an Escherichia coli system. To investigate the role of the ATPase in the regulation of the intracellular pH, the expression of the operon between pH 5.7 and 7.5 was studied. An increase in both the ATPase activity and the amount of the alpha and beta F1 subunits as shown by Western blot analysis was observed as the pH decreased. These increases were accompanied by an increase in the atp-specific mRNA, as shown by Northern blot and slot-blot analysis. Primer extension experiments and transcriptional fusions between the atp promoter and the reporter cat gene demonstrated that this pH-dependent increase in the mRNA was regulated at the level of initiation of transcription. Transcription of the operon occurs from a promoter with a consensus -35 box (TTGACA) and a -10 box (TACACT) that differs from the consensus (TATAAT). A point mutation at the -10 box of the promoter (change to TGCACT) avoided this increase, suggesting a role for this sequence in the pH-inducible regulation.

  20. beta-Lactamase-producing Moraxella catarrhalis may prevent the emergence of penicillin-resistant Streptococcus pneumoniae in children with recurrent acute otitis media.

    PubMed

    Joki-Erkkilä, Veli-Pekka; Aittoniemi, Janne; Vuento, Risto; Puhakka, Heikki

    2002-05-15

    We studied the effect of concomitant nasopharyngeal carriage of beta-lactamase producing Moraxella catarrhalis and Haemophilus influenzae on the occurrence of penicillin resistance of Streptococcus pneumoniae. We took nasopharyngeal samples from 306 children with recurrent otitis media and a history of several antibiotic treatments. We could isolate at least one of the pathogens in 89 subjects. Of these children 13% carried more than one pathogen. Of the isolated M. catarrhalis and H. influenzae strains 93% and 43% produced beta-lactamase, respectively. Of the S. pneumoniae strains 25% were non-susceptible (I/R) to penicillin. However, in patients carrying beta-lactamase-producing M. catarrhalis together with pneumococci all strains were susceptible to penicillin (P=0.0353). This finding suggests that beta-lactamase producing M. catarrhalis may hinder the emergence of penicillin resistance of S. pneumoniae in children with recurrent acute otitis media.

  1. RlmCD-mediated U747 methylation promotes efficient G748 methylation by methyltransferase RlmAII in 23S rRNA in Streptococcus pneumoniae; interplay between two rRNA methylations responsible for telithromycin susceptibility

    PubMed Central

    Shoji, Tatsuma; Takaya, Akiko; Sato, Yoshiharu; Kimura, Satoshi; Suzuki, Tsutomu; Yamamoto, Tomoko

    2015-01-01

    Adenine at position 752 in a loop of helix 35 from positions 745 to 752 in domain II of 23S rRNA is involved in binding to the ribosome of telithromycin (TEL), a member of ketolides. Methylation of guanine at position 748 by the intrinsic methyltransferase RlmAII enhances binding of telithromycin (TEL) to A752 in Streptococcus pneumoniae. We have found that another intrinsic methylation of the adjacent uridine at position 747 enhances G748 methylation by RlmAII, rendering TEL susceptibility. U747 and another nucleotide, U1939, were methylated by the dual-specific methyltransferase RlmCD encoded by SP_1029 in S. pneumoniae. Inactivation of RlmCD reduced N1-methylated level of G748 by RlmAII in vivo, leading to TEL resistance when the nucleotide A2058, located in domain V of 23S rRNA, was dimethylated by the dimethyltransferase Erm(B). In vitro methylation of rRNA showed that RlmAII activity was significantly enhanced by RlmCD-mediated pre-methylation of 23S rRNA. These results suggest that RlmCD-mediated U747 methylation promotes efficient G748 methylation by RlmAII, thereby facilitating TEL binding to the ribosome. PMID:26365244

  2. Antibacterial resistance in Streptococcus pyogenes (GAS) from healthy carriers and tonsillitis patients and association with antibacterial sale in the Faroe Islands.

    PubMed

    Magnussen, Marita D; Gaini, Shahin; Gislason, Hannes; Kristinsson, Karl G

    2016-04-01

    The aim of this study was to investigate the antibacterial resistance of Streptococcus pyogenes (GAS), and correlate the findings with the sales of erythromycin and tetracycline. General practitioners in the Faroe Islands were recruited to send oropharyngeal swabs. From an ongoing pneumococcal study, nasopharyngeal swabs were sampled from healthy children 0-7 years of age. Erythromycin susceptibility data from Iceland were obtained from the reference laboratory at the Landspitali University Hospital. Susceptibility testing in the Faroe Islands and Iceland was performed according to CLSI methods and criteria. The resistance rate to erythromycin and tetracycline found in patients in the Faroe Islands in 2009/2010 was 6% and 30% respectively. Tetracycline resistance in patients declined significantly from 2009 to 2010 (37-10%, p-value = 0.006 < 0.05) and differed significantly between age groups (p-value = 0.03 < 0.05). In Iceland, there was a peak in erythromycin resistance in 2008 (44%) and a substantial decrease in 2009 (5%). Although the prevalence of erythromycin and tetracycline resistance in the Faroe Islands and Iceland may be associated with antimicrobial use, sudden changes can occur with the introduction of new resistant clones.

  3. Helminth Infection Promotes Colonization Resistance via Type 2 Immunity

    PubMed Central

    Ramanan, Deepshika; Bowcutt, Rowann; Lee, Soo Ching; Tang, Mei San; Kurtz, Zachary D.; Ding, Yi; Honda, Kenya; Gause, William C.; Blaser, Martin J.; Bonneau, Richard A.; Lim, Yvonne AL; Loke, P’ng; Cadwell, Ken

    2016-01-01

    Increasing incidence of inflammatory bowel diseases such as Crohn’s disease (CD) in developed nations is associated with changes to the environment, such as decreased prevalence of helminth colonization and alterations to the gut microbiota. We find that helminth infection protects mice deficient in the CD susceptibility gene Nod2 from intestinal abnormalities by inhibiting colonization with an inflammatory Bacteroides species. Colonization resistance to Bacteroides was dependent on type-2 immunity, which promoted the establishment of a protective microbiota enriched in Clostridiales. Additionally, we show that individuals from helminth-endemic regions harbor a similar protective microbiota, and that deworming treatment reduced Clostridiales and increased Bacteroidales. These results support a model of the hygiene hypothesis whereby certain individuals are genetically susceptible to the consequences of a changing microbial environment. PMID:27080105

  4. Antimicrobial resistance in Scandinavia after ban of antimicrobial growth promoters.

    PubMed

    Bengtsson, Björn; Wierup, Martin

    2006-01-01

    The banned use of antimicrobial growth promoters resulted in a considerably decreased use of antimicrobials in food animal production in Sweden (65%), Denmark (47%), Norway (40%) and Finland (27%). The current prevalence of antimicrobial resistance in animal bacterial populations is also considerably lower than in some other countries in the EU. In the swine production, no or limited effect was found in the finisher production (>25 to 30 kg). Temporary negative effects occurred during the post weaning period (7-30 kg). In Denmark, the cost of production from birth to slaughter per pig produced increased by approximately 1.0 euro with a high variability between pig producers. In the broiler production the termination had no significant negative effect on animal health and welfare or on production economy.

  5. Helminth infection promotes colonization resistance via type 2 immunity.

    PubMed

    Ramanan, Deepshika; Bowcutt, Rowann; Lee, Soo Ching; Tang, Mei San; Kurtz, Zachary D; Ding, Yi; Honda, Kenya; Gause, William C; Blaser, Martin J; Bonneau, Richard A; Lim, Yvonne A L; Loke, P'ng; Cadwell, Ken

    2016-04-29

    Increasing incidence of inflammatory bowel diseases, such as Crohn's disease, in developed nations is associated with changes to the microbial environment, such as decreased prevalence of helminth colonization and alterations to the gut microbiota. We find that helminth infection protects mice deficient in the Crohn's disease susceptibility gene Nod2 from intestinal abnormalities by inhibiting colonization by an inflammatory Bacteroides species. Resistance to Bacteroides colonization was dependent on type 2 immunity, which promoted the establishment of a protective microbiota enriched in Clostridiales. Additionally, we show that individuals from helminth-endemic regions harbor a similar protective microbiota and that deworming treatment reduced levels of Clostridiales and increased Bacteroidales. These results support a model of the hygiene hypothesis in which certain individuals are genetically susceptible to the consequences of a changing microbial environment. Copyright © 2016, American Association for the Advancement of Science.

  6. Surveillance of antibiotic resistance in clinical isolates of Streptococcus pneumoniae collected in Belgium during winter 2000-2001.

    PubMed

    Vanhoof, R; Carpentier, M; Cartuyvels, R; Damée, S; Fagnart, O; Garrino, M G; Glupczynski, Y; Gordts, B; Govaerts, D; Magerman, K; Mans, I; Surmont, I; Van Bossuyt, E; Van De Vyvere, M; Van Landuyt, H; Van Nimmen, L; Van Noyen, R

    2003-01-01

    A total of 314 isolates of Streptococcus pneumoniae collected by 10 different laboratories were tested for their susceptibility by using a microdilution technique following NCCLS recommendations. The following antibiotics were included: penicillin, ampicillin, amoxicillin, amoxicillin/clavulanate, cefaclor, cefuroxime, cefotaxime, imipenem, ciprofloxacin, gemifloxacin, levofloxacin, erythromycin, clarithromycin, azithromycin, miocamycin, clindamycin and tetracycline. The insusceptibility rate (IR) to penicillin was 21.0% [10.8% intermediate (> or = 0.12-1 microgram/mL) and 10.2% high-level (> or = 2 micrograms/mL)], to cefotaxime 7.3% [3.5% intermediate (> or = 1 microgram/mL) and 3.8% high-level (> or = 2 micrograms/mL)], to imipenem 3.8% [3.8% intermediate (> or = 0.25-0.5 microgram/mL) and 0% high-level (> or = 1 microgram/mL)], to ciprofloxacin 11.2% [8.3% intermediate (2 micrograms/mL) and 3.9% high-level (> or = 4 micrograms/mL)], to erythromycin 30.3% [3.5% intermediate (0.5 microgram/mL) and 26.8% high-level (> or = 1 microgram/mL)] and to tetracycline 38.5% [0.9% intermediate (4 micrograms/mL) and 37.6% high-level (> or = 8 micrograms/mL)]. No decreased susceptibility was found for gemifloxacin (> or = 0.5 microgram/mL). This compound was the most active with MIC50, MIC90 and an IR of 0.015 microgram/mL, 0.03 microgram/mL and 0% respectively, followed by amoxicillin/clavulanate, amoxicillin and imipenem (MIC50, MIC90 and IR: 0.015 microgram/mL, 1 microgram/mL, 1.6%/0.015 microgram/mL, 1 microgram/mL, 1.9%/0.008 microgram/mL, 0.12 microgram/mL, 3.8% respectively). Compared to the 1999 surveillance, penicillin and tetracycline-insusceptibility increased with 4.9% and 15.6% respectively, while cefotaxime, erythromycin and ciprofloxacin insusceptibility decreased with 5.4%, 5.8% and 4.4% respectively. MICs of all beta-lactams rose with those of penicillin for penicillin-insusceptible isolates. Imipenem, cefotaxime, amoxicillin and amoxicillin/clavulanate were

  7. Risk factors for development of multiple-class resistance to Streptococcus pneumoniae Strains in Belgium over a 10-year period: antimicrobial consumption, population density, and geographic location.

    PubMed

    Van Eldere, Johan; Mera, Robertino M; Miller, Linda A; Poupard, James A; Amrine-Madsen, Heather

    2007-10-01

    We investigated the impact of the usage of antibiotics in ambulatory patients in Belgium in 147 defined geographical circumscriptions and at the individual isolate level. The study included 14,448 Streptococcus pneumoniae strains collected by the Belgium national reference lab from 1994 to 2004. Additional risk factors for resistance, such as population density/structure and day care attendance, were investigated for the same time-space window. A statistical model that included resistance to two or more antimicrobial classes offered the best fit for measuring the changes in nonsusceptibility to penicillin, macrolides, and tetracycline over time and place in Belgium. Analysis at the geographic level identified antimicrobial consumption with a 1-year lag (0.5% increase per additional defined daily dose) and population density as independent predictors of multiple resistance. Independent risk factors at the isolate level were age (odds ratio [OR], 1.55 for children aged <5 years), population density (7% increase in multiple resistance per 100 inhabitants/km(2)), conjugate 7-valent vaccine serotype (OR, 14.3), location (OR, 1.55 for regions bordering high-resistance France), and isolate source (OR, 1.54 for ear isolates). The expansion of multiple-resistant strains explains most of the overall twofold increase and subsequent decrease in single antimicrobial resistance between 1994 and 2004. We conclude that factors in addition to antibiotic use, such as high population density and proximity to high-resistance regions, favor multiple resistance. Regional resistance rates are not linearly related to actual antibiotic use but are linked to past antibiotic use plus a combination of demographic and geographic factors.

  8. [Resistance to non-beta-lactam antibiotics in the clinical isolates of Streptococcus pneumoniae of children in Latin America. SIREVA II, 2000-2005].

    PubMed

    Agudelo, Clara Inés; Castañeda, Elizabeth; Corso, Alejandra; Regueira, Mabel; Brandileone, Maria Cristina de Cunto; Brandão, Angela Pires; Maldonado, Aurora; Hormazabal, Juan Carlos; Tamargo, Isis; Echániz-Aviles, Gabriela; Soto, Araceli; Viveros, Mónica Guadalupe; Hernández, Irma; Chamorro, Gustavo; Weiler, Natalie; Sánchez, Jacqueline; Feris, Jesús M; Camou, Teresa; García, Gabriela; Spadola, Enza; Payares, Daisy; Gabastou, Jean-Marc; Di Fabio, José Luis

    2009-04-01

    To examine the development of resistance to erythromycin, chloramphenicol, trimethoprim-sulfamethoxazole (TMP-SMZ), and vancomycin of the invasive isolates of Streptococcus pneumoniae obtained from children in 10 Latin American/Caribbean countries during six years of surveillance. Analysis of 8 993 isolates of S. pneumoniae recovered in 2000-2005 from children with invasive infections, who were less than 6 years of age, and from Argentina, Brazil, Chile, Colombia, Cuba, Dominican Republic, Mexico, Paraguay, Uruguay, or Venezuela. Antibiotic susceptibility was determined through the methods established and standardized by the SIREVA project. Multidrug resistance was defined as: resistance to three or more antibiotics of the same class; to the non-beta-lactams analyzed by this study; or, to the beta-lactams evaluated by a previous study, in which 37.8% of these isolates showed decreased susceptibility to penicillin. Some degree of resistance was found to TMP-SMZ and erythromycin (56.4% and 15.4% of the isolates studied, respectively), with 4.6% highly resistant to chloramphenicol. All isolates were susceptible to vancomycin. The highest prevalence of TMP-SMZ resistance was observed in the pneumonia isolates; and that of erythromycin, in cases of sepsis (61.6% and 25.5%, respectively; P < 0.01). The highest prevalence of TMP-SMZ resistance was found in Brazil (71.9%), and that of erythromycin, in Mexico (38.2%) and Venezuela (32.9%). The 14, 6B, 19F, and 23F serotypes were most often associated with resistance to the antibiotics in the study. High and increasing rates of isolates resistant to TMP-SMZ and erythromycin were observed, as well as a decreasing percentage of isolates resistant to chloramphenicol. These trends highlight differences among the countries studied.

  9. Levofloxacin-ceftriaxone combination attenuates lung inflammation in a mouse model of bacteremic pneumonia caused by multidrug-resistant Streptococcus pneumoniae via inhibition of cytolytic activities of pneumolysin and autolysin.

    PubMed

    Majhi, Arnab; Adhikary, Rana; Bhattacharyya, Aritra; Mahanti, Sayantika; Bishayi, Biswadev

    2014-09-01

    In this study, our objective was to determine whether a synergistic antimicrobial combination in vitro would be beneficial in the downregulation of pneumococcal virulence genes and whether the associated inflammation of the lung tissue induced by multidrug-resistant Streptococcus pneumoniae infection in vivo needs to be elucidated in order to consider this mode of therapy in case of severe pneumococcal infection. We investigated in vivo changes in the expression of these virulence determinants using an efficacious combination determined in previous studies. BALB/c mice were infected with 10(6) CFU of bacteria. Intravenous levofloxacin at 150 mg/kg and/or ceftriaxone at 50 mg/kg were initiated 18 h postinfection; the animals were sacrificed 0 to 24 h after the initiation of treatment. The levels of cytokines, chemokines, and C-reactive protein (CRP) in the serum and lungs, along with the levels of myeloperoxidase and nitric oxide the inflammatory cell count in bronchoalveolar lavage fluid (BALF), changes in pneumolysin and autolysin gene expression and COX-2 and inducible nitric oxide synthase (iNOS) protein expression in the lungs were estimated. Combination therapy downregulated inflammation and promoted bacterial clearance. Pneumolysin and autolysin expression was downregulated, with a concomitant decrease in the expression of COX-2 and iNOS in lung tissue. Thus, the combination of levofloxacin and ceftriaxone can be considered for therapeutic use even in cases of pneumonia caused by drug-resistant isolates.

  10. Levofloxacin-Ceftriaxone Combination Attenuates Lung Inflammation in a Mouse Model of Bacteremic Pneumonia Caused by Multidrug-Resistant Streptococcus pneumoniae via Inhibition of Cytolytic Activities of Pneumolysin and Autolysin

    PubMed Central

    Majhi, Arnab; Adhikary, Rana; Bhattacharyya, Aritra; Mahanti, Sayantika

    2014-01-01

    In this study, our objective was to determine whether a synergistic antimicrobial combination in vitro would be beneficial in the downregulation of pneumococcal virulence genes and whether the associated inflammation of the lung tissue induced by multidrug-resistant Streptococcus pneumoniae infection in vivo needs to be elucidated in order to consider this mode of therapy in case of severe pneumococcal infection. We investigated in vivo changes in the expression of these virulence determinants using an efficacious combination determined in previous studies. BALB/c mice were infected with 106 CFU of bacteria. Intravenous levofloxacin at 150 mg/kg and/or ceftriaxone at 50 mg/kg were initiated 18 h postinfection; the animals were sacrificed 0 to 24 h after the initiation of treatment. The levels of cytokines, chemokines, and C-reactive protein (CRP) in the serum and lungs, along with the levels of myeloperoxidase and nitric oxide the inflammatory cell count in bronchoalveolar lavage fluid (BALF), changes in pneumolysin and autolysin gene expression and COX-2 and inducible nitric oxide synthase (iNOS) protein expression in the lungs were estimated. Combination therapy downregulated inflammation and promoted bacterial clearance. Pneumolysin and autolysin expression was downregulated, with a concomitant decrease in the expression of COX-2 and iNOS in lung tissue. Thus, the combination of levofloxacin and ceftriaxone can be considered for therapeutic use even in cases of pneumonia caused by drug-resistant isolates. PMID:24957840

  11. ACSL4 promotes prostate cancer growth, invasion and hormonal resistance.

    PubMed

    Wu, Xinyu; Deng, Fangming; Li, Yirong; Daniels, Garrett; Du, Xinxin; Ren, Qinghu; Wang, Jinhua; Wang, Ling Hang; Yang, Yang; Zhang, Valerio; Zhang, David; Ye, Fei; Melamed, Jonathan; Monaco, Marie E; Lee, Peng

    2015-12-29

    Increases in fatty acid metabolism have been demonstrated to promote the growth and survival of a variety of cancers, including prostate cancer (PCa). Here, we examine the expression and function of the fatty acid activating enzyme, long-chain fatty acyl-CoA synthetase 4 (ACSL4), in PCa. Ectopic expression of ACSL4 in ACSL4-negative PCa cells increases proliferation, migration and invasion, while ablation of ACSL4 in PCa cells expressing endogenous ACSL4 reduces cell proliferation, migration and invasion. The cell proliferative effects were observed both in vitro, as well as in vivo. Immunohistochemical analysis of human PCa tissue samples indicated ACSL4 expression is increased in malignant cells compared with adjacent benign epithelial cells, and particularly increased in castration-resistant PCa (CRPC) when compared with hormone naive PCa. In cell lines co-expressing both ACSL4 and AR, proliferation was independent of exogenous androgens, suggesting that ACSL4 expression may lead to CRPC. In support for this hypothesis, ectopic ACSL4 expression induced resistance to treatment with Casodex, via decrease in apoptosis. Our studies further indicate that ACSL4 upregulates distinct pathway proteins including p-AKT, LSD1 and β-catenin. These results suggest ACSL4 could serve as a biomarker and potential therapeutic target for CRPC.

  12. Dietary sodium alginate administration affects fingerling growth and resistance to Streptococcus sp. and iridovirus, and juvenile non-specific immune responses of the orange-spotted grouper, Epinephelus coioides.

    PubMed

    Yeh, Shinn-Pyng; Chang, Chen-An; Chang, Chi-Yao; Liu, Chun-Hung; Cheng, Winton

    2008-07-01

    administration at 1.0 and 2.0 g kg(-1), respectively, to promote growth and enhance immunity and resistance against Streptococcus sp. and an iridovirus.

  13. Molecular and antimicrobial susceptibility profiling of atypical Streptococcus species from porcine clinical specimens.

    PubMed

    Moreno, Luisa Z; Matajira, Carlos E C; Gomes, Vasco T M; Silva, Ana Paula S; Mesquita, Renan E; Christ, Ana Paula G; Sato, Maria Inês Z; Moreno, Andrea M

    2016-10-01

    The Streptococcus species present broad phenotypic variation, making identification difficult using only traditional microbiological methods. Even though Streptococcus suis is the most important species for the worldwide swine industry, other Streptococcus species appear to be able to cause disease in swine and could represent a higher underestimated risk for porcine health. The aim of this study was to identify Streptococcus-like isolates by MALDI-TOF MS and 16S rRNA sequencing and further molecular and antibiotic susceptibility characterization of the atypical Streptococcus species capable of causing disease in swine. Fifty presumptive Streptococcus isolates from diseased pigs isolated from different Brazilian States between 2002 and 2014 were evaluated. Among the studied isolates, 26% were identified as Streptococcus hyovaginalis, 24% as Streptococcus plurianimalium, 12% as Streptococcus alactolyticus, 10% as Streptococcus hyointestinalis, and the remaining isolates belonged to Streptococcus henryi (6%), Streptococcus thoraltensis (6%), Streptococcus gallolyticus (6%), Streptococcus gallinaceus (4%), Streptococcus sanguinis (4%), and Streptococcus mitis (2%). The Streptococcus isolates were successfully identified by spectral cluster analysis and 16S rRNA sequencing with 96% of concordance between the techniques. The SE-AFLP analysis also supported Streptococcus species distinction and enabled further observation of higher genetic heterogeneity intra-species. The identified Streptococcus species presented variable MIC values to β-lactams, enrofloxacin and florfenicol, and high resistance rates to tetracyclines and macrolides, which appear to be directly related to the industry's antimicrobial usage and resistance selection. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. [A comparison of the activities of membrane-bound, proton translocating ATPases between Streptococcus mutans fluoride-resistant and their parent strains].

    PubMed

    Sheng, Jiang-Yun; Huang, Zheng-Wei; Liu, Zheng

    2005-02-01

    To figure out the reason for increased acid tolerance of Ingbritt-FR, the fluoride-resistant strain of Streptococcus mutans Ingbritt, by determining and comparing the H(+)-ATPase activities of both fluoride-resistant and their parental strains. The permeabilized cells of S. mutans Ingbritt and Ingbritt-FR were prepared by treating them with 10% toluene and then two cycles of freezing and thawing. The permeabilized cells were used for ATPase assay by adding them to the reaction mixture which contained 50mM Tris-maleate buffer (pH 6.0), 10 mM MgSO4 and 5 mM ATP. ATPase activity was assessed by measuring inorganic phosphate released from ATP hydrolysis.Two-way ANOVA was used for statistical analysis. The activities of H(+)-ATPase of Ingbritt-FR were 308.48, 136.67, and 82.80 micromol Pi/g cell dry weight/min, at 10, 20, and 60 minutes respectively, significantly higher than those of their parent strain: 104.77, 64.69, and 30.7 (P<0.01). The enzyme activities were decreasing with time. The higher ATPase activity of fluoride-resistant mutant of S. mutans Ingbritt may account for the increased acid tolerance of this organism, and the increment of ATPase activity and acid tolerance of fluoride-resistant strain is likely to increase the cariogenic potential of S. mutans after fluoride-resistant mutation.

  15. In vitro activity of beta-lactams, macrolides, telithromycin, and fluoroquinolones against clinical isolates of Streptococcus pneumoniae: correlation between drug resistance and genetic characteristics.

    PubMed

    Yamaguchi, Toshiyuki; Hashikita, Giichi; Takahashi, Shun; Itabashi, Akira; Yamazaki, Tsutomu; Maesaki, Shigefumi

    2005-10-01

    The in vitro activity of antimicrobial agents against Streptococcus pneumoniae was determined using 16 strains of penicillin-susceptible S. pneumoniae (PSSP) and 26 strains of penicillin intermediately resistant S. pneumoniae (PISP) + penicillin-resistant S. pneumoniae (PRSP) in Japan. The minimum inhibitory concentrations (MICs) of potent antibiotics, including eight beta-lactams (benzylpenicillin, ampicillin, cefotiam, cefepime, cefditoren, faropenem, panipenem, and biapenem), three macrolides (erythromycin, clarithromycin, and azithromycin), telithromycin, and three fluoroquinolones (ciprofloxacin, levofloxacin, and gatifloxacin), were determined. Twenty-three strains exhibited genetic variations at pbp1a + pbp2x + pbp2b, which are genetic-PRSP (g-PRSP). g-PISP strains accounted for 62.5% (10/16) of the PSSP strains. The existence of an abnormal pbp gene conferred not only penicillin resistance but resistance to cephems; however, panipenem and biapenem had potent in vitro efficacy against alterations. Regarding the macrolide resistance mechanisms (mefA or ermB): 16 isolates had only mefA, 18 isolates had ermB, and 2 isolates had both mefA and ermB. There was no correlation between the existence of an abnormal pbp gene and the existence of the mefA gene or the ermB gene.

  16. Growth response and resistance to Streptococcus iniae of Nile tilapia, Oreochromis niloticus, fed diets containing different levels of wheat distiller dried grains with solubles with or without lysine supplementation

    USDA-ARS?s Scientific Manuscript database

    A study was conducted to evaluate the effect of dietary levels of wheat distiller’s dried grains with solubles (DDGS) with or without lysine supplementation on growth, body composition, hematology, immune response, and resistance of Nile tilapia, Oreochromis niloticus, to Streptococcus iniae challen...

  17. Streptococcus pyogenes CAMP factor promotes bacterial adhesion and invasion in pharyngeal epithelial cells without serum via PI3K/Akt signaling pathway.

    PubMed

    Kurosawa, Mie; Oda, Masataka; Domon, Hisanori; Isono, Toshihito; Nakamura, Yuki; Saitoh, Issei; Hayasaki, Haruaki; Yamaguchi, Masaya; Kawabata, Shigetada; Terao, Yutaka

    2017-09-23

    Streptococcus pyogenes is a bacterium that causes systemic diseases, such as pharyngitis and toxic shock syndrome, via oral- or nasal-cavity infection. S. pyogenes produces various molecules known to function with serum components that lead to bacterial adhesion and invasion in human tissues. In this study, we identified a novel S. pyogenes adhesin/invasin. Our results revealed that CAMP factor promoted streptococcal adhesion and invasion in pharyngeal epithelial Detroit562 cells without serum. Recombinant CAMP factor initially localized on the membranes of cells and then became internalized in the cytosol following S. pyogenes infection. Additionally, CAMP factor phosphorylated phosphoinositide 3-kinase and serine-threonine kinase in the cells. ELISA results demonstrate that CAMP factor affected the amount of phosphorylated phosphoinositide 3-kinase and serine-threonine kinase in Detroit562 cells. Furthermore, CAMP factor did not reverse the effect of phosphoinositide 3-kinase knockdown by small interfering RNA in reducing the level of adhesion and invasion of S. pyogenes isogenic cfa-deficient mutant. These results suggested that S. pyogenes CAMP factor activated the phosphoinositide 3-kinase/serine-threonine kinase signaling pathway, promoting S. pyogenes invasion of Detroit562 cells without serum. Our findings suggested that CAMP factor played an important role on adhesion and invasion in pharyngeal epithelial cells. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  18. Camel Streptococcus agalactiae populations are associated with specific disease complexes and acquired the tetracycline resistance gene tetM via a Tn916-like element

    PubMed Central

    2013-01-01

    Camels are the most valuable livestock species in the Horn of Africa and play a pivotal role in the nutritional sustainability for millions of people. Their health status is therefore of utmost importance for the people living in this region. Streptococcus agalactiae, a Group B Streptococcus (GBS), is an important camel pathogen. Here we present the first epidemiological study based on genetic and phenotypic data from African camel derived GBS. Ninety-two GBS were characterized using multilocus sequence typing (MLST), capsular polysaccharide typing and in vitro antimicrobial susceptibility testing. We analysed the GBS using Bayesian linkage, phylogenetic and minimum spanning tree analyses and compared them with human GBS from East Africa in order to investigate the level of genetic exchange between GBS populations in the region. Camel GBS sequence types (STs) were distinct from other STs reported so far. We mapped specific STs and capsular types to major disease complexes caused by GBS. Widespread resistance (34%) to tetracycline was associated with acquisition of the tetM gene that is carried on a Tn916-like element, and observed primarily among GBS isolated from mastitis. The presence of tetM within different MLST clades suggests acquisition on multiple occasions. Wound infections and mastitis in camels associated with GBS are widespread and should ideally be treated with antimicrobials other than tetracycline in East Africa. PMID:24083845

  19. Interaction of factor H-binding protein of Streptococcus suis with globotriaosylceramide promotes the development of meningitis.

    PubMed

    Kong, Decong; Chen, Zhe; Wang, Junping; Lv, Qingyu; Jiang, Hua; Zheng, Yuling; Xu, Maokai; Zhou, Xuyu; Hao, Huaijie; Jiang, Yongqiang

    2017-04-12

    Streptococcus suis is an important emerging zoonotic agent that causes acute bacterial meningitis in humans with high mortality and morbidity. Our previous work showed that factor H-binding protein (Fhb) contributed to virulence of S. suis, but the role of Fhb in the development of S. suis meningitis remained unclear. In this study, we demonstrated for the first time that Fhb contributed to the traversal of S. suis across the human blood-brain barrier by allelic-exchange mutagenesis, complementation and specific antibody blocking studies. We also showed that globotriaosylceramide (Gb3), the receptor of Fhb, was involved in this process and affected S. suis infection-induced activation of myosin light chain 2 through Rho/ROCK signaling in hCMEC/D3 cells. Using a murine model of S. suis meningitis, we further demonstrated that Gb3-deficiency prevented the mice from developing severe brain inflammation or injury. Our results demonstrate that the Fhb-Gb3 interaction plays an important role in the development of S. suis meningitis and might be a potential therapeutic target against S. suis infection.

  20. Antibiotic susceptibility pattern and erythromycin resistance mechanisms in beta-hemolytic group G Streptococcus dysgalactiae subspecies equisimilis isolates from central Taiwan.

    PubMed

    Lo, Hsueh-Hsia; Nien, Hao-Hsiang; Cheng, Ya-Yu; Su, Fang-Yi

    2015-12-01

    Information concerning antibiotics susceptibilities of beta-hemolytic group G Streptococcus dysgalactiae subspecies equisimilis (SDSE) clinical isolates in central Taiwan was limited. Totally, 246 SDSE isolates were collected from mainly five regional hospitals, from February 2007 to August 2011. Disk diffusion method, broth microdilution method, and clindamycin induction test (D test) were respectively performed according to the guidelines of the Clinical and Laboratory Standards Institute. Polymerase chain reaction was used to detect the corresponding erythromycin resistance genes. All isolates were susceptible to penicillin, cefotaxime, and vancomycin. The rate of erythromycin resistance was 24.0% (59/246), whereas that of clindamycin resistance was 12.2% (30/246). The resistance rates of isolates from different hospitals varied from 15.0% to 45.5% for erythromycin and from 7.1% to 36.4% for clindamycin. For erythromycin-resistant SDSE isolates, three different phenotypes with resistance to macrolides (M), lincosamides (L), and type B streptogramins (SB) were observed: M (49.2%), constitutive MLSB (cMLSB, 35.6%), and inducible MLSB (iMLSB, 15.3%). All M phenotypic isolates carried mefA. The most prevalent genotypes among cMLSB and iMLSB phenotypic isolates were ermB, followed by ermTR. One isolate with cMLSB phenotype carried both ermB and ermTR, whereas one isolate with iMLSB phenotype carried both ermB and ermC. This is the first trial investigating the antimicrobial susceptibility pattern and erythromycin resistance mechanisms of beta-hemolytic group G SDSE isolates in central Taiwan. The resistance rates for both erythromycin and clindamycin varied significantly among hospitals located in this area and should be monitored continuously in the future. Copyright © 2014. Published by Elsevier B.V.

  1. Cancer cell mitochondria confer apoptosis resistance and promote metastasis.

    PubMed

    Kulawiec, Mariola; Owens, Kjerstin M; Singh, Keshav K

    2009-07-01

    Mutations in mtDNA are found in most cancers. In this study, we studied the role of cancer cell mutant mtDNA in tumorigenesis. We sequenced the entire mitochondrial genome of three different breast cancer cell lines and found that all three, MCF7, MDA-MB-231 and MDA-MB-435, contained mutations in mtDNA. MDA-MB-435 cells contained a mutation in the tRNA(Leu(CUN)) gene known to be involved in pathogenesis of mitochondrial diseases. We generated a mutant cybrid (cytoplasmic hybrid) by repopulating the recipient rho(0) (completely devoid of mtDNA) cells with donor mtDNA derived from an enucleated MDA-MB-435 breast cancer cell line. An isogenic wild-type cybrid was produced by transfer of normal mtDNA from a healthy donor. When compared to the wild type, we found that mutant mtDNA increases mitochondrial membrane potential. However, this increase in mitochondrial membrane potential was not associated with increase in reactive oxygen species (ROS) production. MtDNA mutations conferred resistance to apoptosis triggered by etoposide. Our study also revealed that mutations in mtDNA increase metastatic potential. Using a tail-vein model of metastasis in a mouse model, we show that the mutant cybrid metastatizes to the lungs and forms macrometastic foci. Additionally we found that mutations in mtDNA constitutively activate the PI3/Akt pathway that contributes to increased metastatis. Together our study demonstrates that mutant mtDNA promotes apoptotic resistance and metastasis in a mouse model.

  2. Relationship between mutations in parC and gyrA of clinical isolates of Streptococcus pneumoniae and resistance to ciprofloxacin and grepafloxacin.

    PubMed

    Stewart, B A; Johnson, A P; Woodford, N

    1999-12-01

    The mechanisms of resistance to ciprofloxacin and grepafloxacin were studied in 54 clinical isolates of Streptococcus pneumoniae. Restriction fragment length polymorphism analysis following HinfI digestion was used with DNA sequencing to identify mutations in the quinolone resistance-determining regions (QRDRs) of the parC and gyrA genes. Ciprofloxacin MICs up to 16 mg/L were not associated with mutations to these genes in approximately half of the isolates. In other isolates, moderate levels of ciprofloxacin resistance (MIC 8-16mg/L) were associated with an alteration of ParC, most commonly entailing replacement of serine-79 by phenylalanine. High-level ciprofloxacin resistance (MIC 32-128 mg/L) entailed the additional mutation of GyrA with substitution of serine-83 by phenylalanine. Grepafloxacin MICs >4 mg/L were associated with this GyrA mutation alone; no relationship was detected between grepafloxacin MICs and mutation of the QRDR of parC.

  3. Overexpression of patA and patB, which encode ABC transporters, is associated with fluoroquinolone resistance in clinical isolates of Streptococcus pneumoniae.

    PubMed

    Garvey, Mark I; Baylay, Alison J; Wong, Ryan L; Piddock, Laura J V

    2011-01-01

    Fifty-seven clinical isolates of Streptococcus pneumoniae were divided into four groups based on their susceptibilities to the fluoroquinolones ciprofloxacin and norfloxacin and the dyes ethidium bromide and acriflavine. Comparative reverse transcription-PCR was used to determine the level of expression of the genes patA and patB, which encode putative ABC transporters. Overexpression was observed in 14 of the 15 isolates that were resistant to both fluoroquinolones and dyes and in only 3 of 24 of those resistant to fluoroquinolones only. Isolates overexpressing patA and patB accumulated significantly less of the fluorescent dye Hoechst 33342 than wild-type isolates, suggesting that PatA and PatB are involved in efflux. Inactivation of patA and patB by in vitro mariner mutagenesis conferred hypersusceptibility to ethidium bromide and acriflavine in all isolates tested and lowered the MICs of ciprofloxacin in the patAB-overproducing and/or fluoroquinolone-resistant isolates. These data represent the first observation of overexpression of patA and patB in clinical isolates and show that PatA and PatB play a clinically relevant role in fluoroquinolone resistance.

  4. Overexpression of patA and patB, Which Encode ABC Transporters, Is Associated with Fluoroquinolone Resistance in Clinical Isolates of Streptococcus pneumoniae▿

    PubMed Central

    Garvey, Mark I.; Baylay, Alison J.; Wong, Ryan L.; Piddock, Laura J. V.

    2011-01-01

    Fifty-seven clinical isolates of Streptococcus pneumoniae were divided into four groups based on their susceptibilities to the fluoroquinolones ciprofloxacin and norfloxacin and the dyes ethidium bromide and acriflavine. Comparative reverse transcription-PCR was used to determine the level of expression of the genes patA and patB, which encode putative ABC transporters. Overexpression was observed in 14 of the 15 isolates that were resistant to both fluoroquinolones and dyes and in only 3 of 24 of those resistant to fluoroquinolones only. Isolates overexpressing patA and patB accumulated significantly less of the fluorescent dye Hoechst 33342 than wild-type isolates, suggesting that PatA and PatB are involved in efflux. Inactivation of patA and patB by in vitro mariner mutagenesis conferred hypersusceptibility to ethidium bromide and acriflavine in all isolates tested and lowered the MICs of ciprofloxacin in the patAB-overproducing and/or fluoroquinolone-resistant isolates. These data represent the first observation of overexpression of patA and patB in clinical isolates and show that PatA and PatB play a clinically relevant role in fluoroquinolone resistance. PMID:20937787

  5. Antimicrobial resistance of Streptococcus pneumoniae recovered from outpatients in the United States during the winter months of 1994 to 1995: results of a 30-center national surveillance study.

    PubMed

    Doern, G V; Brueggemann, A; Holley, H P; Rauch, A M

    1996-05-01

    A total of 1,527 clinically significant outpatient isolates of Streptococcus pneumoniae were prospectively collected in 30 different U.S. medical centers between November 1994 and April 1995. Overall, 23.6% of strains were not susceptible to penicillin, with 14.1% intermediate and 9.5% high-level resistant. The frequencies of recovery of intermediate and high-level resistant strains varied considerably between different medical centers and in different geographic areas. In general, intermediate and high-level penicillin resistance was most common with isolates of S. pneumoniae recovered from pediatric patients. The in vitro activities of 22 other antimicrobial agents were assessed against this collection of isolates. Ampicillin was consistently 1 twofold dilution less active than penicillin. Amoxicillin and amoxicillin-clavulanate were essentially equivalent to penicillin in activity. The rank order of activity for cephalosporins was cefotaxime = ceftriaxone > or = cefpodoxime > or = cefuroxime > cefprozil > or = cefixime > cefaclor = loracarbef > cefadroxil = cephalexin. The National Committee for Clinical Laboratory Standards [Performance Standards for Antimicrobial Susceptibility Testing, Sixth Information Supplement (M100-S6), 1995] has established MIC breakpoints for resistance (i.e., > or = 2 micrograms/ml) with three cephalosporins versus S. pneumoniae, namely, cefotaxime, ceftriaxone, and cefuroxime. The overall percentages of strains resistant to these three antimicrobial agents were 3, 5, and 12, respectively. The overall frequency of resistance was 10% with all three macrolides examined in this study, clarithromycin, erythromycin, and azithromycin. The overall percentages of chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole resistance were 4.3, 7.5, and 18, respectively. The resistance percentages among the cephalosporins, macrolides, chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole were consistently higher among penicillin

  6. Antimicrobial resistance of Streptococcus pneumoniae recovered from outpatients in the United States during the winter months of 1994 to 1995: results of a 30-center national surveillance study.

    PubMed Central

    Doern, G V; Brueggemann, A; Holley, H P; Rauch, A M

    1996-01-01

    A total of 1,527 clinically significant outpatient isolates of Streptococcus pneumoniae were prospectively collected in 30 different U.S. medical centers between November 1994 and April 1995. Overall, 23.6% of strains were not susceptible to penicillin, with 14.1% intermediate and 9.5% high-level resistant. The frequencies of recovery of intermediate and high-level resistant strains varied considerably between different medical centers and in different geographic areas. In general, intermediate and high-level penicillin resistance was most common with isolates of S. pneumoniae recovered from pediatric patients. The in vitro activities of 22 other antimicrobial agents were assessed against this collection of isolates. Ampicillin was consistently 1 twofold dilution less active than penicillin. Amoxicillin and amoxicillin-clavulanate were essentially equivalent to penicillin in activity. The rank order of activity for cephalosporins was cefotaxime = ceftriaxone > or = cefpodoxime > or = cefuroxime > cefprozil > or = cefixime > cefaclor = loracarbef > cefadroxil = cephalexin. The National Committee for Clinical Laboratory Standards [Performance Standards for Antimicrobial Susceptibility Testing, Sixth Information Supplement (M100-S6), 1995] has established MIC breakpoints for resistance (i.e., > or = 2 micrograms/ml) with three cephalosporins versus S. pneumoniae, namely, cefotaxime, ceftriaxone, and cefuroxime. The overall percentages of strains resistant to these three antimicrobial agents were 3, 5, and 12, respectively. The overall frequency of resistance was 10% with all three macrolides examined in this study, clarithromycin, erythromycin, and azithromycin. The overall percentages of chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole resistance were 4.3, 7.5, and 18, respectively. The resistance percentages among the cephalosporins, macrolides, chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole were consistently higher among penicillin

  7. Bacterial Superantigens Promote Acute Nasopharyngeal Infection by Streptococcus pyogenes in a Human MHC Class II-Dependent Manner

    PubMed Central

    Kasper, Katherine J.; Zeppa, Joseph J.; Wakabayashi, Adrienne T.; Xu, Stacey X.; Mazzuca, Delfina M.; Welch, Ian; Baroja, Miren L.; Kotb, Malak; Cairns, Ewa; Cleary, P. Patrick; Haeryfar, S. M. Mansour; McCormick, John K.

    2014-01-01

    Establishing the genetic determinants of niche adaptation by microbial pathogens to specific hosts is important for the management and control of infectious disease. Streptococcus pyogenes is a globally prominent human-specific bacterial pathogen that secretes superantigens (SAgs) as ‘trademark’ virulence factors. SAgs function to force the activation of T lymphocytes through direct binding to lateral surfaces of T cell receptors and class II major histocompatibility complex (MHC-II) molecules. S. pyogenes invariably encodes multiple SAgs, often within putative mobile genetic elements, and although SAgs are documented virulence factors for diseases such as scarlet fever and the streptococcal toxic shock syndrome (STSS), how these exotoxins contribute to the fitness and evolution of S. pyogenes is unknown. Here we show that acute infection in the nasopharynx is dependent upon both bacterial SAgs and host MHC-II molecules. S. pyogenes was rapidly cleared from the nasal cavity of wild-type C57BL/6 (B6) mice, whereas infection was enhanced up to ∼10,000-fold in B6 mice that express human MHC-II. This phenotype required the SpeA superantigen, and vaccination with an MHC –II binding mutant toxoid of SpeA dramatically inhibited infection. Our findings indicate that streptococcal SAgs are critical for the establishment of nasopharyngeal infection, thus providing an explanation as to why S. pyogenes produces these potent toxins. This work also highlights that SAg redundancy exists to avoid host anti-SAg humoral immune responses and to potentially overcome host MHC-II polymorphisms. PMID:24875883

  8. Oral cavities of healthy infants harbour high proportions of Streptococcus salivarius strains with phenotypic and genotypic resistance to multiple classes of antibiotics.

    PubMed

    Palma, Thaís H; Harth-Chú, Erika N; Scott, Jodie; Stipp, Rafael N; Boisvert, Heike; Salomão, Mariana F; Theobaldo, Jéssica D; Possobon, Rosana F; Nascimento, Leandro C; McCafferty, Jonathan W; Faller, Lina; Duncan, Margaret J; Mattos-Graner, Renata O

    2016-12-01

    Emerging antibiotic resistance in the oropharyngeal microbiota, of which Streptococcus salivarius is a prominent species, represents a challenge for treating paediatric populations. In this study, we investigated the role of Streptococcussalivarius as a reservoir for antibiotic resistance genes (ARG) in the oral microbiota by analysing 95 Streptococcussalivarius isolates from 22 healthy infants (2-16 months of age). MICs of penicillin G, amoxicillin, erythromycin, tetracycline, doxycycline and streptomycin were determined. ARG profiles were assessed in a subset of 21 strains by next-generation sequencing of genomes, followed by searches of assembled reads against the Comprehensive Antibiotic Resistance Database. Strains resistant to erythromycin, penicillins and tetracyclines were isolated from 83.3, 33.3 and 16.6 %, respectively, of infants aged 2 to 8 months with no prior antibiotic treatment. These percentages were100.0, 66.6 and 50.0 %, by 13 to 16 months of age. ARG or polymorphisms associated with antibiotic resistance were the most prevalent and involved genes for macrolide efflux (mel, mefA/E and macB), ribosomal protection [erm(B), tet(M) and tet(O)] and β-lactamase-like proteins. Phylogenetically related strains showing multidrug-resistant phenotypes harboured multidrug efflux ARG. Polymorphic genes associated with antibiotic resistance to drugs affecting DNA replication, folate synthesis, RNA/protein synthesis and regulators of antibiotic stress responses were detected. These data imply that Streptococcussalivarius strains established during maturation of the oral microbiota harbour a diverse array of functional ARG, even in the absence of antibiotic selective pressures, highlighting a potential role for this species in shaping antibiotic susceptibility profiles of oropharyngeal communities.

  9. Comparison of drug sensitivity and genotypes of clinically isolated strains of levofloxacin-resistant Streptococcus pneumoniae obtained from Okinawa Island, the Japanese main island and Hong Kong.

    PubMed

    Sunagawa, Satoko; Fujita, Jiro; Higa, Futoshi; Tateyama, Masao; Haranaga, Shusaku; Nakasone, Isamu; Yamane, Nobuhisa; Uno, Tsukasa

    2011-08-01

    The prevalence of fluoroquinolone-resistant Streptococcus pneumoniae is increasing worldwide. In the present study, a comparison of drug sensitivity and genotypes of clinically isolated strains of levofloxacin (LVFX)-resistant S. pneumoniae obtained from Hong Kong, Okinawa Island and the Japanese main island (Honshu) was performed. MICs of quinolones (LVFX, tosufloxacin, ciprofloxacin, gatifloxacin and sitafloxacin (STFX)) and other antibiotics (penicillin G, cefcapene, cefditoren, clarithromycin and azithromycin) were determined by a microdilution broth method according to the Clinical and Laboratory Standards Institute Standards. The quinolone-resistance determining regions (QRDRs) of gyrA, gyrB, parC and parE of these strains were analyzed by PCR-based sequencing. All 40 strains tested had more than one amino-acid substitution in the QRDRs of gyrA, gyrB, parC or parE. Although there seemed to be some clonality in strains obtained from Hong Kong, there was no clonality in strains obtained from Okinawa and Japan. Strains obtained from Hong Kong, Okinawa Island and the Japanese main island were genetically different by pulsed-field gel electrophoresis analysis. The range of MIC values of STFX against isolates resistant to LVFX (MIC 4-32 mg l(-1)) was 0.12-0.5 mg l(-1), and MIC(80) values of STFX against LVFX-resistant isolates were 0.25 mg l(-1). This study suggests that LVFX-resistant S. pneumoniae is similar in all three locations and STFX is potent against LVFX-resistant S. pneumoniae with multiple mutations in QRDRs of gyrase A and topoisomerase IV.

  10. [1997-2007, 10 years of monitoring the evolution of resistance of Streptococcus pneumoniae to antibiotics in the region Centre; review of the Pneumococcus network].

    PubMed

    Holstein, A; Amirault, P; Arnould, J-P; Bachelier, M-N; Benseddik, Z; Bret, L; Cahiez, M; Cattier, B; Chandesris, C; Chieux, V; Courouble, G; Domelier, A-S; Graveron, J-L; Harriau, P; Lartigue, M-F; Laudat, P; Poisson, D; Secher, A; Goudeau, A; Lanotte, P

    2010-02-01

    Regional pneumococcal observatories in region Centre, created in 1997, participate with the others pneumococcal observatories alongside the National Reference Center for Pneumococci and the Institut de Veille Sanitaire at the monitoring of the evolution of resistance of pneumococci to antibiotics in France. Between 1997 and 2007, 2427 strains of Streptococcus pneumoniae were isolated in part from cerebrospinal fluids, blood and middle ear fluid, from children and adults. The prevalence of pneumococci with a decreased susceptibility to penicillin (PDSP) decreased strongly in region Centre: 56.8 % in 2001, 39.6 % en 2007. These data are similar to the French national data over the same period. Copyright (c) 2009 Elsevier Masson SAS. All rights reserved.

  11. Determination of Trimethoprim-Sulfamethoxazole Resistance in Streptococcus pneumoniae by Using the E Test with Mueller-Hinton Agar Supplemented with Sheep or Horse Blood May Be Unreliable

    PubMed Central

    Lovgren, M.; Dell’Acqua, L.; Palacio, R.; Echániz-Aviles, G.; Soto-Noguerón, A.; Castañeda, E.; Agudelo, C. I.; Heitmann, I.; Brandileone, M. C.; Zanella, R. C.; Rossi, A.; Pace, J.; Talbot, J. A.

    1999-01-01

    An international, multicenter study compared trimethoprim-sulfamethoxazole MICs for 743 Streptococcus pneumoniae isolates (107 to 244 isolates per country) by E test, using Mueller-Hinton agar supplemented with 5% defibrinated horse blood or 5% defibrinated sheep blood, with MICs determined by the National Committee for Clinical Laboratory Standards broth microdilution reference method. Agreement within 1 log2 dilution and minor error rates were 69.3 and 15.5%, respectively, on sheep blood-supplemented agar and 76.9 and 13.6%, respectively, with horse blood as the supplement. Significant interlaboratory variability was observed. E test may not be a reliable method for determining the resistance of pneumococci to trimethoprim-sulfamethoxazole. PMID:9854095

  12. Optimisation of storage conditions for maintaining culturability of penicillin-susceptible and penicillin-resistant isolates of Streptococcus pneumoniae in transport medium.

    PubMed

    Mason, C K; Goldsmith, C E; Moore, J E; McCarron, P; Leggett, P; Montgomery, J; Coulter, W A

    2010-01-01

    Methods employed by the World Health Organization (WHO) are used during this study to determine the optimum storage conditions for maintaining the culturability of Streptococcus pneumoniae in skimmed milk, tryptone, glucose and glycerin (STGG) transport medium. A comparison of S. pneumoniae strains sensitive and resistant to penicillin showed no significant difference in their survival ability in STGG medium. Furthermore, it is confirmed that storage at -70 degrees C remains most effective for maintaining viability by culture of S. pneumoniae. Storage at -20 degrees C would only be acceptable in the short-term, while storage at +4 degrees C is not recommended. Of note, this study has shown STGG medium at room temperature to be an efficient growth medium for pneumococci in the short-term. This work will help to establish robust sampling protocols when performing community studies to ensure culturability of comparison between community and laboratory pneumococci survival.

  13. dpr and sod in Streptococcus mutans are involved in coexistence with S. sanguinis, and PerR is associated with resistance to H2O2.

    PubMed

    Fujishima, Kei; Kawada-Matsuo, Miki; Oogai, Yuichi; Tokuda, Masayuki; Torii, Mitsuo; Komatsuzawa, Hitoshi

    2013-03-01

    Large numbers of bacteria coexist in the oral cavity. Streptococcus sanguinis, one of the major bacteria in dental plaque, produces hydrogen peroxide (H(2)O(2)), which interferes with the growth of other bacteria. Streptococcus mutans, a cariogenic bacterium, can coexist with S. sanguinis in dental plaque, but to do so, it needs a means of detoxifying the H(2)O(2) produced by S. sanguinis. In this study, we investigated the association of three oxidative stress factors, Dpr, superoxide dismutase (SOD), and AhpCF, with the resistance of S. sanguinis to H(2)O(2). The knockout of dpr and sod significantly increased susceptibility to H(2)O(2), while the knockout of ahpCF had no apparent effect on susceptibility. In particular, dpr inactivation resulted in hypersensitivity to H(2)O(2). Next, we sought to identify the factor(s) involved in the regulation of these oxidative stress genes and found that PerR negatively regulated dpr expression. The knockout of perR caused increased dpr expression levels, resulting in low-level susceptibility to H(2)O(2) compared with the wild type. Furthermore, we evaluated the roles of perR, dpr, and sod when S. mutans was cocultured with S. sanguinis. Culturing of the dpr or sod mutant with S. sanguinis showed a significant decrease in the S. mutans population ratio compared with the wild type, while the perR mutant increased the ratio. Our results suggest that dpr and sod in S. mutans are involved in coexistence with S. sanguinis, and PerR is associated with resistance to H(2)O(2) in regulating the expression of Dpr.

  14. Moraxella catarrhalis outer membrane vesicles carry β-lactamase and promote survival of Streptococcus pneumoniae and Haemophilus influenzae by inactivating amoxicillin.

    PubMed

    Schaar, Viveka; Nordström, Therése; Mörgelin, Matthias; Riesbeck, Kristian

    2011-08-01

    Moraxella catarrhalis is a common pathogen found in children with upper respiratory tract infections and in patients with chronic obstructive pulmonary disease during exacerbations. The bacterial species is often isolated together with Streptococcus pneumoniae and Haemophilus influenzae. Outer membrane vesicles (OMVs) are released by M. catarrhalis and contain phospholipids, adhesins, and immunomodulatory compounds such as lipooligosaccharide. We have recently shown that M. catarrhalis OMVs exist in patients upon nasopharyngeal colonization. As virtually all M. catarrhalis isolates are β-lactamase positive, the goal of this study was to investigate whether M. catarrhalis OMVs carry β-lactamase and to analyze if OMV consequently can prevent amoxicillin-induced killing. Recombinant β-lactamase was produced and antibodies were raised in rabbits. Transmission electron microscopy, flow cytometry, and Western blotting verified that OMVs carried β-lactamase. Moreover, enzyme assays revealed that M. catarrhalis OMVs contained active β-lactamase. OMVs (25 μg/ml) incubated with amoxicillin for 1 h completely hydrolyzed amoxicillin at concentrations up to 2.5 μg/ml. In functional experiments, preincubation of amoxicillin (10× MIC) with M. catarrhalis OMVs fully rescued amoxicillin-susceptible M. catarrhalis, S. pneumoniae, and type b or nontypeable H. influenzae from β-lactam-induced killing. Our results suggest that the presence of amoxicillin-resistant M. catarrhalis originating from β-lactamase-containing OMVs may pave the way for respiratory pathogens that by definition are susceptible to β-lactam antibiotics.

  15. Toll-like receptor 4 agonistic antibody promotes innate immunity against severe pneumonia induced by coinfection with influenza virus and Streptococcus pneumoniae.

    PubMed

    Tanaka, Akitaka; Nakamura, Shigeki; Seki, Masafumi; Fukudome, Kenji; Iwanaga, Naoki; Imamura, Yoshifumi; Miyazaki, Taiga; Izumikawa, Koichi; Kakeya, Hiroshi; Yanagihara, Katsunori; Kohno, Shigeru

    2013-07-01

    Coinfection with bacteria is a major cause of mortality during influenza epidemics. Recently, Toll-like receptor (TLR) agonists were shown to have immunomodulatory functions. In the present study, we investigated the effectiveness and mechanisms of the new TLR4 agonistic monoclonal antibody UT12 against secondary pneumococcal pneumonia induced by coinfection with influenza virus in a mouse model. Mice were intranasally inoculated with Streptococcus pneumoniae 2 days after influenza virus inoculation. UT12 was intraperitoneally administered 2 h before each inoculation. Survival rates were significantly increased and body weight loss was significantly decreased by UT12 administration. Additionally, the production of inflammatory mediators was significantly suppressed by the administration of UT12. In a histopathological study, pneumonia in UT12-treated mice was very mild compared to that in control mice. UT12 increased antimicrobial defense through the acceleration of macrophage recruitment into the lower respiratory tract induced by c-Jun N-terminal kinase (JNK) and nuclear factor kappaB (NF-κB) pathway-dependent monocyte chemoattractant protein 1 (MCP-1) production. Collectively, these findings indicate that UT12 promoted pulmonary innate immunity and may reduce the severity of severe pneumonia induced by coinfection with influenza virus and S. pneumoniae. This immunomodulatory effect of UT12 improves the prognosis of secondary pneumococcal pneumonia and makes UT12 an attractive candidate for treating severe infectious diseases.

  16. Free Sialic Acid Acts as a Signal That Promotes Streptococcus pneumoniae Invasion of Nasal Tissue and Nonhematogenous Invasion of the Central Nervous System

    PubMed Central

    Hatcher, Brandon L.; Hale, Joanetha Y.

    2016-01-01

    Streptococcus pneumoniae (pneumococcus) is a leading cause of bacterial meningitis and neurological sequelae in children worldwide. Acute bacterial meningitis is widely considered to result from bacteremia that leads to blood-brain barrier breakdown and bacterial dissemination throughout the central nervous system (CNS). Previously, we showed that pneumococci can gain access to the CNS through a nonhematogenous route without peripheral blood infection. This access is thought to occur when the pneumococci in the upper sinus follow the olfactory nerves and enter the CNS through the olfactory bulbs. In this study, we determined whether the addition of exogenous sialic acid postcolonization promotes nonhematogenous invasion of the CNS. Previously, others showed that treatment with exogenous sialic acid post-pneumococcal infection increased the numbers of CFU recovered from an intranasal mouse model of infection. Using a pneumococcal colonization model, an in vivo imaging system, and a multiplex assay for cytokine expression, we demonstrated that sialic acid can increase the number of pneumococci recovered from the olfactory bulbs and brains of infected animals. We also show that pneumococci primarily localize to the olfactory bulb, leading to increased expression levels of proinflammatory cytokines and chemokines. These findings provide evidence that sialic acid can enhance the ability of pneumococci to disseminate into the CNS and provide details about the environment needed to establish nonhematogenous pneumococcal meningitis. PMID:27354445

  17. Expression of the mef(E) gene encoding the macrolide efflux pump protein increases in Streptococcus pneumoniae with increasing resistance to macrolides.

    PubMed

    Wierzbowski, Aleksandra K; Boyd, Dave; Mulvey, Michael; Hoban, Daryl J; Zhanel, George G

    2005-11-01

    Active macrolide efflux is a major mechanism of macrolide resistance in Streptococcus pneumoniae in many parts of the world, especially North America. In Canada, this active macrolide efflux in S. pneumoniae is predominantly due to acquisition of the mef(E) gene. In the present study, we assessed the mef(E) gene sequence as well as mef(E) expression in variety of low- and high-level macrolide-resistant, clindamycin-susceptible (M-phenotype) S. pneumoniae isolates (erythromycin MICs, 1 to 32 microg/ml; clindamycin MICs, < or = 0.25 microg/ml). Southern blot hybridization with mef(E) probe and EcoRI digestion and relative real-time reverse transcription-PCR were performed to study the mef(E) gene copy number and expression. Induction of mef(E) expression was analyzed by Etest susceptibility testing pre- and postincubation with subinhibitory concentrations of erythromycin, clarithromycin, azithromycin, telithromycin, and clindamycin. The macrolide efflux gene, mef(E), was shown to be a single-copy gene in all 23 clinical S. pneumoniae isolates tested, and expression post-macrolide induction increased 4-, 6-, 20-, and 200-fold in isolates with increasing macrolide resistance (erythromycin MICs 2, 4, 8, and 32 microg/ml, respectively). Sequencing analysis of the macrolide efflux genetic assembly (mega) revealed that mef(E) had a 16-bp deletion 153 bp upstream of the putative start codon in all 23 isolates. A 119-bp intergenic region between mef(E) and mel was sequenced, and a 99-bp deletion was found in 11 of the 23 M-phenotype S. pneumoniae isolates compared to the published mega sequence. However, the mef(E) gene was fully conserved among both high- and low-level macrolide-resistant isolates. In conclusion, increased expression of mef(E) is associated with higher levels of macrolide resistance in macrolide-resistant S. pneumoniae.

  18. An important site in PBP2x of penicillin-resistant clinical isolates of Streptococcus pneumoniae: mutational analysis of Thr338.

    PubMed

    Zerfass, Ilka; Hakenbeck, Regine; Denapaite, Dalia

    2009-03-01

    Penicillin-binding protein 2x (PBP2x) of Streptococcus pneumoniae represents a primary resistance determinant for beta-lactams, and low-affinity PBP2x variants can easily be selected with cefotaxime. Penicillin-resistant clinical isolates of S. pneumoniae frequently contain in their mosaic PBP2x the mutation T338A adjacent to the active site S337, and T338P as well as T338G substitutions are also known. Site-directed mutagenesis has now documented that a single point mutation at position T338 confers selectable levels of beta-lactam resistance preferentially to oxacillin. Despite the moderate impact on beta-lactam susceptibility, the function of the PBP2x mutants appears to be impaired, as can be documented in the absence of a functional CiaRH regulatory system, resulting in growth defects and morphological changes. The combination of low-affinity PBP2x and PBP1a encoded by mosaic genes is known to result in high cefotaxime resistance. In contrast, introduction of a mosaic pbp1a into the PBP2x(T338G) mutant did not lead to increased resistance. However, the mosaic PBP1a gene apparently complemented the PBP2x(T338G) defect, since Cia mutant derivatives grew normally. The data support the view that PBP2x and PBP1a interact with each other on some level and that alterations of both PBPs in resistant clinical isolates have evolved to ensure cooperation between both proteins.

  19. D-Alanylation of Lipoteichoic Acids Confers Resistance to Cationic Peptides in Group B Streptococcus by Increasing the Cell Wall Density

    PubMed Central

    Saar-Dover, Ron; Bitler, Arkadi; Nezer, Ravit; Shmuel-Galia, Liraz; Firon, Arnaud; Shimoni, Eyal; Trieu-Cuot, Patrick; Shai, Yechiel

    2012-01-01

    Cationic antimicrobial peptides (CAMPs) serve as the first line of defense of the innate immune system against invading microbial pathogens. Gram-positive bacteria can resist CAMPs by modifying their anionic teichoic acids (TAs) with D-alanine, but the exact mechanism of resistance is not fully understood. Here, we utilized various functional and biophysical approaches to investigate the interactions of the human pathogen Group B Streptococcus (GBS) with a series of CAMPs having different properties. The data reveal that: (i) D-alanylation of lipoteichoic acids (LTAs) enhance GBS resistance only to a subset of CAMPs and there is a direct correlation between resistance and CAMPs length and charge density; (ii) resistance due to reduced anionic charge of LTAs is not attributed to decreased amounts of bound peptides to the bacteria; and (iii) D-alanylation most probably alters the conformation of LTAs which results in increasing the cell wall density, as seen by Transmission Electron Microscopy, and reduces the penetration of CAMPs through the cell wall. Furthermore, Atomic Force Microscopy reveals increased surface rigidity of the cell wall of the wild-type GBS strain to more than 20-fold that of the dltA mutant. We propose that D-alanylation of LTAs confers protection against linear CAMPs mainly by decreasing the flexibility and permeability of the cell wall, rather than by reducing the electrostatic interactions of the peptide with the cell surface. Overall, our findings uncover an important protective role of the cell wall against CAMPs and extend our understanding of mechanisms of bacterial resistance. PMID:22969424

  20. Nasopharyngeal Carriage of Antimicrobial-Resistant Streptococcus pneumoniae among Young Children Attending 79 Kindergartens and Day Care Centers in Hong Kong

    PubMed Central

    Chiu, Susan S.; Ho, Pak Leung; Chow, Frankie K. H.; Yuen, Kwok Yung; Lau, Yu Lung

    2001-01-01

    Resistance to penicillin and multiple antimicrobial agents among Streptococcus pneumoniae strains is becoming an increasing problem worldwide and in Asia. To determine the prevalence of carriage of S. pneumoniae isolates not susceptible to penicillin in young children, we obtained nasopharyngeal swab specimens from 1,978 children (ages, 2 to 6 years) attending 79 day care centers or kindergartens. Three hundred eighty-three strains of S. pneumoniae were isolated from these children. Fifty-eight percent of these isolates had reduced susceptibility to penicillin, 123 (32.1%) were intermediate, and 100 (26.1%) were resistant. A very high penicillin MIC (4 μg/ml) was found in 3.3% of the isolates. The isolates also demonstrated high rates of resistance to other antimicrobial agents (51.2% to cefaclor, 50.2% to cefuroxime, 42.8% to cefotaxime, 80.7% to trimethoprim-sulfamethoxazole, 77% to erythromycin, 60% to clindamycin, and 33.7% to chloramphenicol). No isolate was resistant to fluoroquinolone. Multidrug resistance (not susceptible to the β-lactams and three or more other classes) was found in 39.4% of the isolates. Risk factors for the carriage of S. pneumoniae not susceptible to penicillin were multiple physician visits in the preceding 3 months and use of antimicrobial agents by the individual or by household members in the preceding 3 months. In the logistic regression analysis, only the use of antimicrobial agents in the preceding 3 months was an independent risk factor (P = 0.004; odds ratio, 2; 95% confidence interval, 1.2 to 3.2). This study demonstrated the high prevalence of antibiotic-resistant S. pneumoniae in healthy young children in the community in Hong Kong. PMID:11557466