Active-Site Protonation States in an Acyl-Enzyme Intermediate of a Class A β-Lactamase with a Monobactam Substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, Jonathan B.; Weiss, Kevin L.; Coates, Leighton

The monobactam antibiotic aztreonam is used to treat cystic fibrosis patients with chronic pulmonary infections colonized by Pseudomonas aeruginosa strains expressing CTX-M extended-spectrum β-lactamases. Several active site residues in class A β-lactamases have been proposed to play key roles in monobactam hydrolysis. The protonation states of these residues have been determined previously for the apo form of a CTX-M β-lactamase. However, they have not yet been determined for a monobactam acyl-enzyme intermediate. Here we used neutron and high-resolution X-ray crystallography to probe the mechanism by which CTX-M extended-spectrum β-lactamases hydrolyze monobactam antibiotics. In these first reported structures of a classmore » A β-lactamase in acyl enzyme complex with aztreonam we directly observed most of the hydrogen atoms (as deuterium) within the active site in the captured acyl-enzyme state between Toho-1 β-lactamase and aztreonam. Although Lys 234 is fully protonated in the acyl-intermediate, we find that Lys 73 is neutral. These findings are consistent with Lys 73 being able to serve as a general base during the acylation part of the catalytic mechanism, in agreement with previous mechanistic proposals.« less

Active-Site Protonation States in an Acyl-Enzyme Intermediate of a Class A β-Lactamase with a Monobactam Substrate

DOE PAGES

Cooper, Jonathan B.; Weiss, Kevin L.; Coates, Leighton; ...

2016-10-24

The monobactam antibiotic aztreonam is used to treat cystic fibrosis patients with chronic pulmonary infections colonized by Pseudomonas aeruginosa strains expressing CTX-M extended-spectrum β-lactamases. Several active site residues in class A β-lactamases have been proposed to play key roles in monobactam hydrolysis. The protonation states of these residues have been determined previously for the apo form of a CTX-M β-lactamase. However, they have not yet been determined for a monobactam acyl-enzyme intermediate. Here we used neutron and high-resolution X-ray crystallography to probe the mechanism by which CTX-M extended-spectrum β-lactamases hydrolyze monobactam antibiotics. In these first reported structures of a classmore » A β-lactamase in acyl enzyme complex with aztreonam we directly observed most of the hydrogen atoms (as deuterium) within the active site in the captured acyl-enzyme state between Toho-1 β-lactamase and aztreonam. Although Lys 234 is fully protonated in the acyl-intermediate, we find that Lys 73 is neutral. These findings are consistent with Lys 73 being able to serve as a general base during the acylation part of the catalytic mechanism, in agreement with previous mechanistic proposals.« less

Efficacy and Safety of Inhaled Aztreonam Lysine for Airway Pseudomonas in Cystic Fibrosis

PubMed Central

Retsch-Bogart, George Z.; Quittner, Alexandra L.; Gibson, Ronald L.; Oermann, Christopher M.; McCoy, Karen S.; Montgomery, A. Bruce; Cooper, Peter J.

2009-01-01

Background: We assessed the short-term efficacy and safety of aztreonam lysine for inhalation (AZLI [an aerosolized monobactam antibiotic]) in patients with cystic fibrosis (CF) and Pseudomonas aeruginosa (PA) airway infection. Methods: In this randomized, double-blind, placebo-controlled, international study (AIR-CF1 trial; June 2005 to April 2007), patients (n = 164; ≥ 6 years of age) with FEV1 ≥ 25% and ≤ 75% predicted values, and no recent use of antipseudomonal antibiotics or azithromycin were treated with 75 mg of AZLI (three times daily for 28 days) or placebo (1:1 randomization), then were monitored for 14 days after study drug completion. The primary efficacy end point was change in patient-reported respiratory symptoms (CF-Questionnaire-Revised [CFQ-R] Respiratory Scale). Secondary end points included changes in pulmonary function (FEV1), sputum PA density, and nonrespiratory CFQ-R scales. Adverse events and minimum inhibitory concentrations of aztreonam for PA were monitored. Results: After 28 days of treatment, AZLI improved the mean CFQ-R respiratory score (9.7 points; p < 0.001), FEV1 (10.3% predicted; p < 0.001), and sputum PA density (− 1.453 log10 cfu/g; p < 0.001), compared with placebo. Significant improvements in Eating, Emotional Functioning, Health Perceptions, Physical Functioning, Role Limitation/School Performance, and Vitality CFQ-R scales were observed. Adverse events were consistent with symptoms of CF lung disease and were comparable for AZLI and placebo except the incidence of “productive cough” was reduced by half in AZLI-treated patients. PA aztreonam susceptibility at baseline and end of therapy were similar. Conclusions: In patients with CF, PA airway infection, moderate-to-severe lung disease, and no recent use of antipseudomonal antibiotics or azithromycin, 28-day treatment with AZLI significantly improved respiratory symptoms and pulmonary function, and was well tolerated. Trial registration: Clinicaltrials.gov Identifier: NCT00112359 PMID:19420195

Polymyxin Combinations Combat Escherichia coli Harboring mcr-1 and blaNDM-5: Preparation for a Postantibiotic Era.

PubMed

Bulman, Zackery P; Chen, Liang; Walsh, Thomas J; Satlin, Michael J; Qian, Yuli; Bulitta, Jürgen B; Peloquin, Charles A; Holden, Patricia N; Nation, Roger L; Li, Jian; Kreiswirth, Barry N; Tsuji, Brian T

2017-07-25

The rapid increase of carbapenem resistance in Gram-negative bacteria has resurrected the importance of the polymyxin antibiotics. The recent discovery of plasmid-mediated polymyxin resistance ( mcr - 1 ) in carbapenem-resistant Enterobacteriaceae serves as an important indicator that the golden era of antibiotics is under serious threat. We assessed the bacterial killing of 15 different FDA-approved antibiotics alone and in combination with polymyxin B in time-killing experiments against Escherichia coli MCR1_NJ, the first reported isolate in the United States to coharbor mcr-1 and a New Delhi metallo-β-lactamase gene ( bla NDM-5 ). The most promising regimens were advanced to the hollow-fiber infection model (HFIM), where human pharmacokinetics for polymyxin B, aztreonam, and amikacin were simulated over 240 h. Exposure to polymyxin B monotherapy was accompanied by MCR1_NJ regrowth but not resistance amplification (polymyxin B MIC from 0 to 240 h [MIC 0h to MIC 240h ] of 4 mg/liter), whereas amikacin monotherapy caused regrowth and simultaneous resistance amplification (amikacin MIC 0h of 4 mg/liter versus MIC 240h of >64 mg/liter). No MCR1_NJ colonies were observed for any of the aztreonam-containing regimens after 72 h. However, HFIM cartridges for both aztreonam monotherapy and the polymyxin B-plus-aztreonam regimen were remarkably turbid, and the presence of long, filamentous MCR1_NJ cells was evident in scanning electron microscopy, suggestive of a nonreplicating persister (NRP) phenotype. In contrast, the 3-drug combination of polymyxin B, aztreonam, and amikacin provided complete eradication (>8-log 10 CFU/ml reduction) with suppression of resistance and prevention of NRP formation. This is the first comprehensive pharmacokinetic/pharmacodynamic study to evaluate triple-drug combinations for polymyxin- and carbapenem-resistant E. coli coproducing MCR-1 and NDM-5 and will aid in the preparation for a so-called "postantibiotic" era. IMPORTANCE A global health crisis may be on the horizon, as the golden era of antibiotics is under serious threat. We recently reported the first case in the United States of a highly resistant, Escherichia coli so-called "superbug" (MCR1_NJ), coharboring two of the most worrying antibiotic resistance genes, encoding mobile colistin resistance ( mcr - 1 ) and a New Delhi metallo-β-lactamase ( bla NDM-5 ). Worryingly, the medical community is vulnerable to this emerging bacterial threat because optimal treatment strategies are undefined. Here, we report the activity of an optimized combination using simulated human doses of commercially available antibiotics against MCR1_NJ. A unique triple combination involving a cocktail of polymyxin B, aztreonam, and amikacin eradicated the MCR-1- and NDM-5-producing E. coli Each antimicrobial agent administered as monotherapy or in double combinations failed to eradicate MCR1_NJ at a high inoculum. To our knowledge, this is the first study to propose 3-drug therapeutic solutions against superbugs coharboring mcr-1 and bla NDM , seeking to prepare clinicians for future occurrences of these pathogens. Copyright © 2017 Bulman et al.

Acute bilateral ECT in a depressed patient with a hip-aztreonam-spacer and subsequent maintenance ECT after prosthesis collocation.

PubMed

Gálvez, Verònica; de Arriba Arnau, Aida; Martínez-Amorós, Erika; Ribes, Carmina; Urretavizcaya, Mikel; Cardoner, Narcís

2014-11-10

ABSTRACT Electroconvulsive Therapy (ECT) has been demonstrated to be a safe and effective treatment for geriatric depression, although its application might be challenging when medical comorbidities exist. The present case reports a 78-year-old man diagnosed with recurrent unipolar major depressive disorder (MDD), who presented with a severe depressive episode with psychotic features (DSM IV). He successfully received a course of bitemporal (BT) ECT with a hip-aztreonam-spacer due to a hip fracture that occurred during hospitalization. This was followed by maintenance ECT (M-ECT) with a recent prosthesis collocation. This particular case illustrates the importance of a multidisciplinary approach in geriatric patients with somatic complications receiving ECT.

Systemic perioperative prophylaxis in elective oncological colorectal surgery: cefotetan versus clindamicin plus aztreonam.

PubMed

Bellantone, R; Pacelli, F; Sofo, L; Doglietto, G B; Bossola, M; Ratto, C; Crucitti, F

1988-01-01

A prospective randomized study was performed with 65 patients undergoing elective surgery for colorectal cancer, to evaluate the prophylactic effect of two different parenteral antibiotic regimens. All patients underwent rigorous mechanical cleansing of the bowel (enemas, laxatives), received low-residue diet 3 days pre-operatively, and were given oral metronidazole (250 mg) five times a day for 3 days preoperatively. They were divided into two groups comparable in age, nutritional status and operative procedure. The patients in group A (36) received 2 g i.v. of cefotetan at induction of anaesthesia and two other administrations every 12 h. Patients in group B (29) were given clindamicin (600 mg, i.v.) at induction of anaesthesia plus aztreonam (1 g, i.v.); two other doses of the same combined antibiotics were administered every 8 h. Five patients were excluded from the study because they underwent Miles procedure; two others because they underwent explorative laparotomy only. The overall incidence of post-operative septic complications was 6.9% (4/58). No significant differences were found in terms of the rate of surgical infections: 3.1 in group A (1/32) and 0% in group B. Urinary tract infections (1 case) and respiratory tract infections (2 cases) were observed only in group B: the rate was found to be 11.5% (3/26); two anastomotic leakages were observed in group A (6.25%) and one in group B (3.8%). These data suggest that cefotetan appears to be as effective as clindamicin plus aztreonam in prophylaxis against infection in elective colorectal surgery.

The effects of inhaled aztreonam on the cystic fibrosis lung microbiome.

PubMed

Heirali, Alya A; Workentine, Matthew L; Acosta, Nicole; Poonja, Ali; Storey, Douglas G; Somayaji, Ranjani; Rabin, Harvey R; Whelan, Fiona J; Surette, Michael G; Parkins, Michael D

2017-05-05

Aztreonam lysine for inhalation (AZLI) is an inhaled antibiotic used to treat chronic Pseudomonas aeruginosa infection in CF. AZLI improves lung function and quality of life, and reduces exacerbations-improvements attributed to its antipseudomonal activity. Given the extremely high aztreonam concentrations achieved in the lower airways by nebulization, we speculate this may extend its spectrum of activity to other organisms. As such, we sought to determine if AZLI affects the CF lung microbiome and whether community constituents can be used to predict treatment responsiveness. Patients were included if they had chronic P. aeruginosa infection and repeated sputum samples collected before and after AZLI. Sputum DNA was extracted, and the V3-hypervariable region of the 16S ribosomal RNA (rRNA) gene amplified and sequenced. Twenty-four patients naïve to AZLI contributed 162 samples. The cohort had a median age of 37.1 years, and a  median FEV 1 of 44% predicted. Fourteen patients were a priori defined as responders for achieving ≥3% FEV 1 improvement following initiation. No significant changes in alpha diversity were noted following AZLI. Furthermore, beta diversity demonstrated clustering with respect to patients, but had no association with AZLI use. However, we did observe a decline in the relative abundance of several individual operational taxonomic units (OTUs) following AZLI initiation suggesting that specific sub-populations of organisms may be impacted. Patients with higher abundance of Staphylococcus and anaerobic organisms including Prevotella and Fusobacterium were less likely to respond to therapy. Results from our study suggest potential alternate/additional mechanisms by which AZLI functions. Moreover, our study suggests that the CF microbiota may be used as a biomarker to predict patient responsiveness to therapy suggesting the microbiome may be harnessed for the personalization of therapies.

An Improved Extended-Spectrum-β-Lactamase Detection Test Utilizing Aztreonam plus Clavulanate.

PubMed

Thomson, Gina K; Ayaz, Maaz; Lutes, Kelli; Thomson, Kenneth S

2018-01-01

Clinical laboratories test for extended-spectrum β-lactamases (ESBLs) for epidemiological and infection control purposes and also for the potential of cephalosporins to cause therapeutic failures. Testing can be problematic, because the CLSI does not recommend the testing of all producers of ESBLs and also falsely negative results may occur with isolates that coproduce AmpC. Boronic acid-supplemented tests can enhance ESBL detection in AmpC producers. Because aztreonam inhibits AmpCs, a study was designed to compare ESBL detection by the CLSI disk test (CLSI), a boronic acid-supplemented CLSI disk test (CLSI plus BA), and an aztreonam plus clavulanate disk test (ATM plus CA). The study tested 100 well-characterized Enterobacteriaceae , Acinetobacter baumannii , and Pseudomonas aeruginosa isolates. Seventy produced TEM, SHV, or CTX-M ESBLs, with 15 coproducing an AmpC and 11 coproducing a metallo-β-lactamase. Thirty ESBL-negative isolates were also tested. Tests were inoculated by CLSI methodology and interpreted as positive if an inhibitor caused a zone diameter increase of ≥5 mm. The percentages of ESBL producers detected were as follows: ATM plus CA, 95.7%; CLSI plus BA, 88.6%; and CLSI, 78.6%. When AmpC was coproduced, the sensitivities of the tests were as follows: ATM plus CA, 100%; CLSI plus BA, 93.3%; and CLSI, 60%. ATM plus CA also detected an ESBL in 90.1% of isolates that coproduced a metallo-β-lactamase. Falsely positive tests occurred only with the CLSI and CLSI plus BA tests. Overall, the ATM plus CA test detected ESBLs more accurately than the CLSI and CLSI plus BA tests, especially with isolates coproducing an AmpC or metallo-β-lactamase. Copyright © 2017 American Society for Microbiology.

In-vitro susceptibility of 1982 respiratory tract pathogens and 1921 urinary tract pathogens against 19 antimicrobial agents: a Canadian multicentre study. Canadian Antimicrobial Study Group.

PubMed

Blondeau, J M; Yaschuk, Y; Suter, M; Vaughan, D

1999-03-01

A total of 3903 pathogens from 48 Canadian medical centres were tested against 19 antimicrobial agents. Five agents showed activity against > or = 90% of all 1982 respiratory tract pathogens tested (ciprofloxacin, 90%; cefoperazone, 91%; ticarcillin/clavulanate, 92%; ceftazidime and imipenem, 93% each). Nine agents had > or = 90% activity against Enterobacteriaceae from respiratory tract infection (cefotaxime and ticarcillin/clavulanate, 90% each; aztreonam, ceftizoxime and ceftriaxone, 91% each; ceftazidime, 93%; ciprofloxacin, 97%; imipenem and netilmicin, 98% each). Similarly, five agents had activity against > or = 90% of all 1921 urinary tract pathogens tested (ciprofloxacin and ticarcillin/clavulanate, 90% each; cefoperazone and netilmicin, 91% each; imipenem, 99%). Nine agents had > or = 95% activity against Enterobacteriaceae from urinary tract infection (ciprofloxacin, 95%; cefotetan, 97%; aztreonam, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone and netilmicin, 98% each; imipenem, 99%). Seventeen agents had activity against > or = 95% of Staphylococcus aureus strains. Susceptibility of Pseudomonas aeruginosa isolates ranged from 2% to 91%.

Active-Site Protonation States in an Acyl-Enzyme Intermediate of a Class A β-Lactamase with a Monobactam Substrate.

PubMed

Vandavasi, Venu Gopal; Langan, Patricia S; Weiss, Kevin L; Parks, Jerry M; Cooper, Jonathan B; Ginell, Stephan L; Coates, Leighton

2017-01-01

The monobactam antibiotic aztreonam is used to treat cystic fibrosis patients with chronic pulmonary infections colonized by Pseudomonas aeruginosa strains expressing CTX-M extended-spectrum β-lactamases. The protonation states of active-site residues that are responsible for hydrolysis have been determined previously for the apo form of a CTX-M β-lactamase but not for a monobactam acyl-enzyme intermediate. Here we used neutron and high-resolution X-ray crystallography to probe the mechanism by which CTX-M extended-spectrum β-lactamases hydrolyze monobactam antibiotics. In these first reported structures of a class A β-lactamase in an acyl-enzyme complex with aztreonam, we directly observed most of the hydrogen atoms (as deuterium) within the active site. Although Lys 234 is fully protonated in the acyl intermediate, we found that Lys 73 is neutral. These findings are consistent with Lys 73 being able to serve as a general base during the acylation part of the catalytic mechanism, as previously proposed. Copyright © 2016 Vandavasi et al.

[Pharmacokinetics and clinical studies on aztreonam in neonates and premature infants (the second report). Study on effectiveness and safety in combination therapy using aztreonam and ampicillin. A study of aztreonam in the Perinatal Co-research Group].

PubMed

Fuji, R; Hashira, S; Tajima, T; Meguro, H; Abe, T; Sakata, H; Kakehashi, H; Fujita, K; Murono, K; Kaeriyama, M

1990-03-01

Pharmacokinetics and clinical effects were studied in a combination therapy with aztreonam (AZT) and ampicillin (ABPC) in neonates and premature infants. The results obtained are summarized as follows. 1. Pharmacokinetics (1) Average serum concentrations at 30 minutes after one-shot intravenous injection of AZT 20 mg/kg and ABPC 25 mg/kg to a 4-7 days age-group of neonates were 41.3 (AZT) and 30.5 (ABPC) micrograms/ml, respectively. They gradually decreased to 14.7 and 2.7 micrograms/ml at 6 hours after the administration, but the concentration of AZT was always higher than that of ABPC. (2) Serum half-lives (T1/2) in the 4-7 days age-group were 3.61 hours for AZT and 1.42 hours for ABPC, thus T1/2 of AZT was longer. However, T1/2 of AZT was scarcely affected in the concomitant administration of ABPC. (3) Urinary excretion of AZT in the concomitant administration to the 4-7 days age-group was 52.7%, which was the same or a little higher comparing to that in AZT alone administration. 2. Clinical studies (1) AZT and ABPC were concomitantly administered to 160 cases and 133 cases were evaluated for efficacy. Pathogenic organisms were identified in 29 cases (Group A) and the efficacy rate was 86.2% (25/29). The number of cases in which pathogenic organisms were not identified (Group B) was 50 and in this group, the efficacy rate was excellent, 94.0% (47/50). AZT and ABPC were concomitantly administered to 54 cases for prophylaxis and in all the cases the administrations showed prophylactic effect. (2) Bacterial changes were confirmed in 21 of the 29 cases in which pathogenic organisms were identified initially and all of these 21 cases showed bacterial eradication, i.e., the bacterial eradication rate in the treatment was 100%. (3) There were 2 cases in which side-effects were observed among the analyzed 152 cases (1.3%). The side effects found were 1 case each of diarrhea and eruption. Abnormal laboratory values were found in 23 cases (15.9%), i.e., eosinophilia (9 cases), platelet-increase (4), elevation of GOT (4), elevation of GOT and GPT (3) and others (3). From the above pharmacokinetics and clinical results, the combination therapy of AZT and ABPC is considered to be one of the useful empiric antibiotic-therapies when pathogenic organisms are unknown in the infections of neonates and premature infants.

Antimicrobial Susceptibility of Escherichia coli Isolated from Fresh-Marketed Nile Tilapia (Oreochromis niloticus)

PubMed Central

Rocha, Rafael dos Santos; Leite, Lana Oliveira; de Sousa, Oscarina Viana; Vieira, Regine Helena Silva dos Fernandes

2014-01-01

The contamination of seafood by bacteria of fecal origin, especially Escherichia coli, is a widely documented sanitary problem. The objective of the present study was to isolate E. coli strains from the gills, muscle, and body surface of farmed Nile tilapias (Oreochromis niloticus) fresh-marketed in supermarkets in Fortaleza (Ceará, Brazil), to determine their susceptibility to antibiotics of different families (amikacin, gentamicin, imipenem, cephalothin, cefotaxime, ciprofloxacin, aztreonam, ampicillin, nalidixic acid, tetracycline, and sulfametoxazol-trimetoprim), and to determine the nature of resistance by plasmid curing. Forty-four strains (body surface = 25, gills = 15, muscle = 4) were isolated, all of which were susceptible to amikacin, aztreonam, cefotaxime, ciprofloxacin, gentamicin, and imipenem. Gill and body surface samples yielded 11 isolates resistant to ampicillin, tetracycline, and sulfametoxazol-trimetoprim, 4 of which of plasmidial nature. The multiple antibiotic resistance index was higher for strains isolated from body surface than from gills. The overall high antibiotic susceptibility of E. coli strains isolated from fresh-marketed tilapia was satisfactory, although the occasional finding of plasmidial resistance points to the need for close microbiological surveillance of the farming, handling, and marketing conditions of aquaculture products. PMID:24808957

Spanish consensus on the prevention and treatment of Pseudomonas aeruginosa bronchial infections in cystic fibrosis patients.

PubMed

Cantón, Rafael; Máiz, Luis; Escribano, Amparo; Olveira, Casilda; Oliver, Antonio; Asensio, Oscar; Gartner, Silvia; Roma, Eva; Quintana-Gallego, Esther; Salcedo, Antonio; Girón, Rosa; Barrio, María Isabel; Pastor, María Dolores; Prados, Concepción; Martínez-Martínez, María Teresa; Barberán, José; Castón, Juan José; Martínez-Martínez, Luis; Poveda, José Luis; Vázquez, Carlos; de Gracia, Javier; Solé, Amparo

2015-03-01

Pseudomonas aeruginosa is the main pathogen in bronchopulmonary infections in cystic fibrosis (CF) patients. It can only be eradicated at early infection stages while reduction of its bacterial load is the therapeutic goal during chronic infection or exacerbations. Neonatal screening and pharmacokinetic/pharmacodynamic knowledge has modified the management of CF-patients. A culture based microbiological follow-up should be performed in patients with no infection with P.aeruginosa. At initial infection, inhaled colistin (0,5-2MU/tid), tobramycin (300mg/bid) or aztreonam (75mg/tid) with or without oral ciprofloxacin (15-20mg/kg/bid, 2-3weeks) are recommended. In chronic infections, treatment is based on continuous administration of colistin or with a 28-day on-off regimen with tobramycin or aztreonam. During mild-moderate exacerbations oral ciprofloxacin (2-3weeks) can be administered while serious exacerbations must be treated with intravenous combination therapy (beta-lactam with an aminoglycoside or a fluoroquinolone). Future studies will support antibiotic rotation and/or new combination therapies. Epidemiological measures are also recommended to avoid new P.aeruginosa infections and "patient-to-patient transmission" of this pathogen. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.

Carbapenem-Resistant Strain of Klebsiella oxytoca Harboring Carbapenem-Hydrolyzing β-Lactamase KPC-2

PubMed Central

Yigit, Hesna; Queenan, Anne Marie; Rasheed, J. Kamile; Biddle, James W.; Domenech-Sanchez, Antonio; Alberti, Sebastian; Bush, Karen; Tenover, Fred C.

2003-01-01

We investigated a Klebsiella oxytoca isolate demonstrating resistance to imipenem, meropenem, extended-spectrum cephalosporins, and aztreonam. The MICs of both imipenem and meropenem were 32 μg/ml. The β-lactamase activity against imipenem and meropenem was inhibited in the presence of clavulanic acid. Isoelectric focusing studies demonstrated five β-lactamases with pIs of 8.2 (SHV-46), 6.7 (KPC-2), 6.5 (unknown), 6.4 (probable OXY-2), and 5.4 (TEM-1). The presence of the blaSHV and blaTEM genes was confirmed by specific PCR assays and DNA sequence analysis. Transformation and conjugation studies with Escherichia coli showed that the β-lactamase with a pI of 6.7, Klebsiella pneumoniae carbapenemase-2 (KPC-2), was encoded on an approximately 70-kb conjugative plasmid that also carried SHV-46, TEM-1, and the β-lactamase with a pI of 6.5. The blaKPC-2 determinant was cloned in E. coli and conferred resistance to imipenem, meropenem, extended-spectrum cephalosporins, and aztreonam. The amino acid sequence of KPC-2 showed a single amino acid difference, S174G, when compared with KPC-1, another carbapenem-hydrolyzing β-lactamase from K. pneumoniae 1534. Hydrolysis studies showed that purified KPC-2 hydrolyzed not only carbapenems but also penicillins, cephalosporins, and aztreonam. KPC-2 had the highest affinity for meropenem. The kinetic studies revealed that KPC-2 was inhibited by clavulanic acid and tazobactam. An examination of the outer membrane proteins of the parent K. oxytoca strain demonstrated that it expressed detectable levels of OmpK36 (the homolog of OmpC) and a higher-molecular-weight OmpK35 (the homolog of OmpF). Thus, carbapenem resistance in K. oxytoca 3127 is due to production of the Bush group 2f, class A, carbapenem-hydrolyzing β-lactamase KPC-2. This β-lactamase is likely located on a transposon that is part of a conjugative plasmid and thus has a very high potential for dissemination. PMID:14638498

Tobramycin-induced hepatotoxicity.

PubMed

Nisly, Sarah A; Ray, Shaunta' M; Moye, Robert A

2007-12-01

To report a case of tobramycin-induced hepatotoxicity. A 20-year-old female was hospitalized for treatment of Pseudomonas aeruginosa bacteremia and osteomyelitis. Empiric intravenous antibiotic therapy with piperacillin/tazobactam, vancomycin, and ciprofloxacin was started, and based on the results of culture and sensitivity testing, was changed to intravenous ceftazidime and tobramycin 70 mg every 8 hours on hospital day 3. Liver enzyme levels then increased over days 3-6. Tests for hepatitis A, B, and C were all nonreactive, and HIV testing was negative. On day 8, therapy was changed from ceftazidime to piperacillin/tazobactam and the tobramycin dose was increased to 100 mg every 8 hours. Due to a continued increase in total bilirubin, aspartate aminotransferase, and alanine aminotransferase, piperacillin/tazobactam was discontinued and aztreonam was started on day 10. All antibiotics were stopped on day 12 and the elevated liver parameters began to decrease. Aztreonam and ciprofloxacin were restarted on day 16, and most laboratory test results returned to baseline levels by day 19; total bilirubin and alkaline phosphatase decreased to lower than baseline values. This case illustrates a possible occurrence of tobramycin-induced hepatotoxicity. Liver enzymes rose when tobramycin therapy was initiated, markedly increased when the tobramycin dose was increased, then resolved upon discontinuation of therapy. Other medication-related causes were ruled out by temporal relationship or rechallenge (aztreonam). Use of the Naranjo probability scale indicated a possible relationship between hepatotoxicity and tobramycin therapy. Other adverse reaction scales specific for evaluation of drug-induced liver disease were also used. Both the Council for International Organizations of Medical Sciences and Maria and Victorino scales indicated a probable likelihood of tobramycin-induced hepatotoxicity. This patient was not rechallenged with tobramycin due to the highly suggestive timeline present, lack of specific symptoms, and unnecessary risk to the patient. Although no other case reports on this interaction have been published through October 9, 2007, historical data from tertiary sources reveal the possibility of aminoglycoside-induced hepatotoxicity; therefore, tobramycin-induced hepatotoxicity cannot be ruled out in this patient. Clinicians should be aware of this adverse event.

Effect of recombinant human granulocyte colony-stimulating factor on combination therapy with aztreonam and clindamycin for infections in neutropenic patients with hematologic diseases.

PubMed

Toyama, K; Yaguchi, M; Mizoguchi, H; Masuda, M; Urabe, A; Ikeda, Y; Aoki, I; Shinbo, T; Togawa, A; Hirashima, K; Miura, Y; Hirose, S; Tsuruoka, N; Omine, M; Kamakura, M; Saito, T; Arimori, S; Aoki, N; Kuraishi, Y; Hirai, H; Asano, S; Mori, M; Shirai, T; Muto, Y; Takaku, F

1996-12-01

The present multicenter study was performed to evaluate the effect of recombinant human granulocyte-colony stimulating factor (rhG-CSF) on combination therapy using aztreonam (AZT) and clindamycin (CLDM) to treat severe infection in neutropenic patients with hematologic diseases. Forty-three neutropenic patients with infections (rhG-CSF group) were treated with AZT (2 g) and CLDM (600 mg) 2-3 times daily as well as rhG-CSF (Lenograstim or Filgrastim: 2-5 mu/kg/day). The clinical efficacy of this regimen was compared to that obtained in 44 febrile neutropenic patients, with hematologic diseases, who received only AZT and CLDM in a previous study (historical control group). The overall efficacy rate was 69.8% (30/43) in the rhG-CSF group and 65.9% (29/44) in the historical control group. Although the neutrophil count was significantly increased and C-reactive protein tended to be lower in the rhG-CSF group, the daily maximum body temperature profiles of the 2 groups were nearly the same. These results suggest that rhG-CSF is of little benefit in the treatment of single infectious episodes in neutropenic patients, and that appropriate antibiotic therapy is more important.

[Pharmacokinetics and clinical evaluations on aztreonam in perinatal infections in obstetrics and gynecology. A study of aztreonam in the perinatal co-research group].

PubMed

Matsuda, S; Oh, K; Hirayama, H; Shimizu, T; Sengoku, K; Haga, H; Inoue, R; Yamazaki, T; Mizoguchi, H; Tori-i, Y

1990-04-01

Pharmacokinetics and clinical studies on an injectable monobactam antibiotic aztreonam (AZT), were carried out in perinatal infections in obstetrics and gynecology and the obtained results are summarized as follows. 1. Pharmacokinetic study (1) Upon one-shot intravenous injection of AZT 1 g before delivery, maternal serum concentration of AZT was 89.0 micrograms/ml immediately after the injection and a half-life (T 1/2) of 0.96 hour was observed. Umbilical-cord serum concentration showed a peak value of 16.5 micrograms/ml at 1.26 hours after the injection and gradually decreased with a T 1/2 of 1.91 hours. The transfer into amniotic fluid was observed and the peak value of AZT in amniotic fluid reached 12.9 micrograms/ml at 5.57 hours after the injection and slowly decreased thereafter with a T 1/2 of 4.42 hours. Transfer and disappearance in one-shot 2 g intravenous injection and 1 g intravenous drip infusion (1 hour) of AZT were very similar to the results obtained with the one-shot 1 g intravenous injection. (2) The residual serum concentration in neonates after one-shot 1 g intravenous injection of AZT to the mother was almost below the detectable limit. Transfer of AZT into milk was scarcely recognized. 2. Clinical studies (1) AZT was injected to 47 cases with various perinatal infections and it was more than "effective" in 45 cases with an efficacy rate of 95.7%. Also, all the 12 cases to which AZT was administered for prophylaxis of infections showed prophylactic effect. Bacterial eradication was obtained with 25 strains out of 29 aerobic Gram-negative bacteria, but 1 strain "persisted" and for 3 strains results were "unknown", hence an eradication rate of 96.2% was obtained. However, AZT treatment resulted in a little lower eradication rate against Gram-positive bacteria. (2) One case (1.3%) of minor degree of urticaria was found as a side effect, and one case each of eosinophilia and elevation of GOT, GPT and Al-P was observed as abnormal laboratory value. From the above results of pharmacokinetics and clinical evaluation, it has been concluded that AZT is a useful and highly safe drug in various perinatal infections and prophylaxis.

beta-Lactam resistance of motile Aeromonas isolates from clinical and environmental sources.

PubMed Central

Morita, K; Watanabe, N; Kurata, S; Kanamori, M

1994-01-01

The MICs of various beta-lactams for 182 isolates of Aeromonas species, i.e., A. hydrophila (n = 101), A. sobria (n = 69), and A. caviae (n = 12), from clinical and environmental sources were determined by an agar dilution technique. All strains were resistant to ampicillin and susceptible to aztreonam. A. sobria and A. caviae demonstrated lower resistance rates than A. hydrophila. Penicillin-hydrolyzing beta-lactamases were detected in all strains. PMID:8192463

Effects of beta-lactamases and omp mutation on susceptibility to beta-lactam antibiotics in Escherichia coli.

PubMed Central

Hiraoka, M; Okamoto, R; Inoue, M; Mitsuhashi, S

1989-01-01

Four types of beta-lactamases consisting of a penicillinase type I (TEM-1), a penicillinase type II (OXA-1), a cephalosporinase of Citrobacter freundii, and a cephalosporinase of Proteus vulgaris were introduced into Escherichia coli MC4100 and its omp mutants, MH1160 (MC4100 ompR1) and MH760 (MC4100 ompR2), by transformation. Effects of the combination of the omp mutations and these beta-lactamases on the susceptibility of E. coli strains were studied with 15 beta-lactam antibiotics including cephalosporins, cephamycins, penicillins, imipenem, and aztreonam. The ompR1 mutant, MH1160, lacks OmpF and OmpC, and it showed reduced susceptibility to 11 of the 15 beta-lactam agents. The reduction in susceptibility to cefoxitin, moxalactam, and flomoxef was much greater than reduction in susceptibility to the other agents. When the ompR1 mutant produced the cephalosporinase of C. freundii, the susceptibility of the mutant to 12 of the 15 beta-lactam antibiotics decreased. The reduction in susceptibility of MH1160 to 10 of the 12 agents affected by the enzyme was two- to fourfold greater than that observed in MC4100. Such a synergistic effect was also observed with the cephalosporinase of P. vulgaris and ompR1 mutation against six cephalosporins, moxalactam, and aztreonam. Images PMID:2658786

IMP-27, a Unique Metallo-β-Lactamase Identified in Geographically Distinct Isolates of Proteus mirabilis.

PubMed

Dixon, Nyssa; Fowler, Randal C; Yoshizumi, A; Horiyama, Tsukasa; Ishii, Y; Harrison, Lucas; Geyer, Chelsie N; Moland, Ellen Smith; Thomson, Kenneth; Hanson, Nancy D

2016-10-01

A novel metallo-β-lactamase gene, blaIMP-27, was identified in unrelated Proteus mirabilis isolates from two geographically distinct locations in the United States. Both isolates harbor blaIMP-27 as part of the first gene cassette in a class 2 integron. Antimicrobial susceptibility testing indicated susceptibility to aztreonam, piperacillin-tazobactam, and ceftazidime but resistance to ertapenem. However, hydrolysis assays indicated that ceftazidime was a substrate for IMP-27. Copyright © 2016 Dixon et al.

Ceftaroline fosamil: a cephalosporin with activity against methicillin-resistant Staphylococcus aureus.

PubMed

Poon, Henry; Chang, Mei H; Fung, Horatio B

2012-04-01

Ceftaroline is a cephalosporin with expanded gram-positive activity recently approved for clinical uses by the US Food and Drug Administration. This article provides an overview of the in vitro and in vivo activities, mechanism of action, pharmacologic and pharmacokinetic properties, clinical efficacy, and tolerability of ceftaroline. Relevant information was identified through a search of PubMed (1990-April 2011), EMBASE (1990-April 2011), International Pharmaceutical Abstracts (1970-April 2011), and Google Scholar using the key words ceftaroline, PPI-0903, PPI-0903M, T-91825, and TAK-599. A review of the reference lists of identified articles, a search of the US Food and Drug Administration Web site, and posters and abstracts from scientific meetings yielded additional publications. In vitro, ceftaroline exhibits activity against most aerobic gram-positive isolates, common aerobic gram-negative respiratory pathogens, and some gram-positive anaerobes. The MIC range for most Staphylococcus aureus isolates, including vancomycin-resistant strains was between ≤0.008 and 4 μg/mL. In Phase III studies (CANVAS 1 and CANVAS 2), ceftaroline was found to be noninferior to vancomycin + aztreonam for the treatment of complicated skin and skin-structure infections, with a clinical cure rate of 91.6% among clinically evaluable patients (ceftaroline versus vancomycin + aztreonam: difference, -1.1; 95% CI, -4.2 to 2.0; P = NS). Ceftaroline's efficacy has also been assessed for the treatment of community-acquired pneumonia in 2 Phase III studies (FOCUS 1 and FOCUS 2) and was equivalent to ceftriaxone, with cure rates of 84.3% and 77.7%, respectively, among clinically evaluable patients in the combined analysis (ceftaroline versus ceftriaxone: difference, 6.7; 95% CI, 1.6 to 11.8). The recommended dosage for patients 18 years and older is 600 mg IV every 12 hours. Dosage adjustment is necessary in patients with renal impairment (creatinine clearance ≤50 mL/min). The pharmacokinetic properties of ceftaroline in patients with hepatic impairments are currently unavailable. Ceftaroline appeared to be well tolerated generally. The most frequently (>3%) reported adverse events were nausea, headaches, diarrhea, pruritus, rash, and insomnia; all were usually mild to moderate, self-limiting, and of little clinical significance. Ceftaroline is a cephalosporin with broad gram-positive activity, including Methicillin-resistant S aureus and vancomycin-resistant S aureus. Its gram-negative activity includes common respiratory pathogens and members of the Enterobacteriaceae. Clinical trials have reported that ceftaroline was noninferior to ceftriaxone, and vancomycin + aztreonam for the treatment of community-acquired pneumonia and complicated skin and skin-structure infections, respectively. Published by EM Inc USA.

Ceftaroline fosamil use in hospitalized patients with acute bacterial skin and skin structure infections: Budget impact analysis from a hospital perspective.

PubMed

Huang, Xingyue; Beresford, Eric; Lodise, Thomas; Friedland, H David

2013-06-15

The budgetary impact of adding ceftaroline fosamil to a hospital formulary for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) was evaluated. A three-year hospital budget impact model was constructed with three initial treatment options for ABSSSIs: ceftaroline fosamil, vancomycin plus aztreonam, and other vancomycin-containing regimens. The target population was hospitalized adult patients with an ABSSSI. Clinical cure rates with initial treatment were assumed to be similar to those from ceftaroline fosamil clinical trials. Patients who did not respond to initial treatment were assumed to be treated successfully with second-line antimicrobial therapy. Length of stay and cost per hospital day (by success or failure with initial treatment) were estimated based on a large database from more than 100 U.S. hospitals. Other model inputs included the annual number of ABSSSI admissions, projected annual case growth rate, proportion of ABSSSI target population receiving vancomycin-containing regimen, expected proportion of ABSSSI target population to be treated with ceftaroline fosamil, drug acquisition cost, cost of antibiotic administration, and cost of vancomycin monitoring. Sensitivity analysis using 95% confidence limits of clinical cure rates was also performed. The estimated total cost of care for treating a patient with an ABSSSI was $395 lower with ceftaroline fosamil ($15,087 versus $15,482) compared with vancomycin plus aztreonam and $72 lower ($15,087 versus $15,159) compared with other vancomycin-containing regimens. Model estimates indicated that adding ceftaroline fosamil to the hospital formulary would not have a negative effect on a hospital's budget for ABSSSI treatment.

Antibiotic Treatment of Experimental Pneumonic Plague in Mice

PubMed Central

Byrne, William R.; Welkos, Susan L.; Pitt, M. Louise; Davis, Kelly J.; Brueckner, Ralf P.; Ezzell, John W.; Nelson, Gene O.; Vaccaro, Joseph R.; Battersby, Luann C.; Friedlander, Arthur M.

1998-01-01

A mouse model was developed to evaluate the efficacy of antibiotic treatment of pneumonic plague; streptomycin was compared to antibiotics with which there is little or no clinical experience. Infection was induced by inhalation of aerosolized Yersinia pestis organisms. Antibiotics were administered by intraperitoneal injection every 6 hours for 5 days, at doses that produced levels of drug in serum comparable to those observed in humans treated for other serious infections. These studies compared in vitro to in vivo activity and evaluated the efficacy of antibiotics started at different times after exposure. Early treatment (started 24 h after challenge, when 0 of 10 mice tested had positive blood cultures) with netilmicin, ciprofloxacin, ofloxacin, ceftriaxone, ceftazidime, aztreonam, ampicillin, and rifampin (but not cefazolin, cefotetan, or ceftizoxime) demonstrated efficacy comparable to streptomycin. Late treatment (started 42 h after exposure, when five of five mice tested had positive blood cultures) with netilmicin, ciprofloxacin, ofloxacin, and a high dose (20 mg/kg of body weight every 6 h) of gentamicin produced survival rates comparable to that with streptomycin, while all of the beta-lactam antibiotics (cefazolin, cefotetan, ceftriaxone, ceftazidime, aztreonam, and ampicillin) and rifampin were significantly inferior to streptomycin. In fact, all groups of mice treated late with beta-lactam antibiotics experienced accelerated mortality rates compared to normal-saline-treated control mice. These studies indicate that netilmicin, gentamicin, ciprofloxacin, and ofloxacin may be alternatives for the treatment of pneumonic plague in humans. However, the beta-lactam antibiotics are not recommended, based upon poor efficacy in this mouse model of pneumonic plague, particularly when pneumonic plague may be associated with bacteremia. PMID:9517950

Ceftaroline fosamil in the treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections.

PubMed

Lodise, Thomas P; Low, Donald E

2012-07-30

Ceftaroline fosamil is a cephalosporin antibacterial approved by the US Food and Drug Administration (FDA) for use in the treatment of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP). After intravenous administration, ceftaroline fosamil is rapidly converted to its bioactive metabolite, ceftaroline. Ceftaroline has broad-spectrum in vitro activity against Gram-positive and Gram-negative bacteria, including contemporary resistant Gram-positive phenotypes, such as methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Streptococcus pneumoniae. Because of its unique spectrum of activity, the Clinical and Laboratory Standards Institute (CLSI) designated ceftaroline as a member of a new subclass of β-lactam antimicrobials, cephalosporins with anti-MRSA activity. The activity of ceftaroline against S. aureus extends to heteroresistant vancomycin-intermediate, vancomycin-intermediate, vancomycin-resistant and daptomycin-nonsusceptible isolates. Ceftaroline has low minimum inhibitory concentrations (MICs) for all tested species of streptococci, and has potent activity against S. pneumoniae isolates with varying degrees of penicillin resistance. The activity of ceftaroline is limited against Enterococcus faecalis and Enterococcus faecium and against anaerobes such as Bacteroides fragilis. The in vitro activity of ceftaroline includes many Gram-negative pathogens, but does not extend to bacteria that produce extended-spectrum β-lactamases, class B metallo-β-lactamases or AmpC cephalosporinases, or to most nonfermentative Gram-negative bacilli. Ceftaroline fosamil has been studied for the treatment of complicated skin and skin structure infections (cSSSI) and community-acquired pneumonia (CAP) in phase III randomized, double-blind, international, multicentre noninferiority clinical trials. Two identical trials (CANVAS 1 and CANVAS 2) compared the efficacy of ceftaroline fosamil with that of vancomycin plus aztreonam in 1378 adults with cSSSI. Results demonstrated that ceftaroline was noninferior to vancomycin plus aztreonam, with 91.6% in the ceftaroline fosamil group (pooled analysis) achieving clinical response compared with 92.7% in the vancomycin plus aztreonam group (difference -1.1%, 95% CI -4.2, 2.0). An additional analysis evaluated clinical cure in a subgroup of patients who met the FDA guidance definition of ABSSSI at treatment day 3. Clinical response, defined as cessation of lesion spread and absence of fever, was 74.0% in the ceftaroline fosamil group compared with 66.2% in the vancomycin plus aztreonam group (treatment difference 7.8%, 95% CI 1.3, 14.0). Clinical efficacy of ceftaroline fosamil in 1240 hospitalized adults with CAP was compared with that of ceftriaxone in two additional phase III trials (FOCUS 1 and FOCUS 2). Of note, because ceftriaxone does not have activity against MRSA, patients with confirmed or suspected MRSA CAP were excluded from the FOCUS trials. Results demonstrated that ceftaroline was noninferior to ceftriaxone, with 84.3% in the ceftaroline fosamil group achieving clinical cure compared with 77.7% in the ceftriaxone group (difference 6.7%, 95% CI 1.6, 11.8). An additional analysis of the trials was conducted in patients with moderate to severe CAP and at least one proven typical bacterial pathogen at baseline (i.e. CABP). Day 4 clinical response rates were 69.5% for ceftaroline and 59.4% for ceftriaxone (difference 10.1%, 95% CI -0.6, 20.6). In the phase III trials, adverse event rates were similar between groups. Overall, ceftaroline is well tolerated, which is consistent with the good safety and tolerability profile of the cephalosporin class. In summary, ceftaroline fosamil is a broad-spectrum parenteral cephalosporin with excellent in vitro activity against resistant Gram-positive pathogens, including MRSA, as well as many common Gram-negative organisms. It is a welcome treatment option for ABSSSI and CABP.

TEM-72, a New Extended-Spectrum β-Lactamase Detected in Proteus mirabilis and Morganella morganii in Italy

PubMed Central

Perilli, Mariagrazia; Segatore, Bernardetta; Rosaria De Massis, Maria; Riccio, Maria Letizia; Bianchi, Ciro; Zollo, Alessandro; Rossolini, Gian Maria; Amicosante, Gianfranco

2000-01-01

A new natural TEM-2 derivative, named TEM-72, was identified in a Proteus mirabilis strain and in a Morganella morganii strain isolated in Italy in 1999. Compared to TEM-1, TEM-72 contains the following amino acid substitutions: Q39K, M182T, G238S, and E240K. Kinetic analysis showed that TEM-72 exhibits an extended-spectrum activity, including activity against oxyimino-cephalosporins and aztreonam. Expression of blaTEM-72 in Escherichia coli was capable of decreasing the host susceptibility to the above drugs. PMID:10952610

Global Dissemination of blaKPC into Bacterial Species beyond Klebsiella pneumoniae and In Vitro Susceptibility to Ceftazidime-Avibactam and Aztreonam-Avibactam.

PubMed

Kazmierczak, Krystyna M; Biedenbach, Douglas J; Hackel, Meredith; Rabine, Sharon; de Jonge, Boudewijn L M; Bouchillon, Samuel K; Sahm, Daniel F; Bradford, Patricia A

2016-08-01

The Klebsiella pneumoniae carbapenemase (KPC), first described in the United States in 1996, is now a widespread global problem in several Gram-negative species. A worldwide surveillance study collected Gram-negative pathogens from 202 global sites in 40 countries during 2012 to 2014 and determined susceptibility to β-lactams and other class agents by broth microdilution testing. Molecular mechanisms of β-lactam resistance among carbapenem-nonsusceptible Enterobacteriaceae and Pseudomonas aeruginosa were determined using PCR and sequencing. Genes encoding KPC enzymes were found in 586 isolates from 22 countries (76 medical centers), including countries in the Asia-Pacific region (32 isolates), Europe (264 isolates), Latin America (210 isolates), and the Middle East (19 isolates, Israel only) and the United States (61 isolates). The majority of isolates were K. pneumoniae (83.4%); however, KPC was detected in 13 additional species. KPC-2 (69.6%) was more common than KPC-3 (29.5%), with regional variation observed. A novel KPC variant, KPC-18 (KPC-3[V8I]), was identified during the study. Few antimicrobial agents tested remained effective in vitro against KPC-producing isolates, with ceftazidime-avibactam (MIC90, 4 μg/ml), aztreonam-avibactam (MIC90, 0.5 μg/ml), and tigecycline (MIC90, 2 μg/ml) retaining the greatest activity against Enterobacteriaceae cocarrying KPC and other β-lactamases, whereas colistin (MIC90, 2 μg/ml) demonstrated the greatest in vitro activity against KPC-positive P. aeruginosa This analysis of surveillance data demonstrated that KPC is widely disseminated. KPC was found in multiple species of Enterobacteriaceae and P. aeruginosa and has now become a global problem. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

A kinetic analysis of the inhibition of FOX-4 β-lactamase, a plasmid-mediated AmpC cephalosporinase, by monocyclic β-lactams and carbapenems

PubMed Central

Papp-Wallace, Krisztina M.; Mallo, Susana; Bethel, Christopher R.; Taracila, Magdalena A.; Hujer, Andrea M.; Fernández, Ana; Gatta, Julian A.; Smith, Kerri M.; Xu, Yan; Page, Malcolm G. P.; Desarbre, Eric; Bou, Germán; Bonomo, Robert A.

2014-01-01

Objectives Class C β-lactamases are prevalent among Enterobacteriaceae; however, these enzymes are resistant to inactivation by commercially available β-lactamase inhibitors. In order to find novel scaffolds to inhibit class C β-lactamases, the comparative efficacy of monocyclic β-lactam antibiotics (aztreonam and the siderophore monosulfactam BAL30072), the bridged monobactam β-lactamase inhibitor BAL29880, and carbapenems (imipenem, meropenem, doripenem and ertapenem) were tested in kinetic assays against FOX-4, a plasmid-mediated class C β-lactamase (pmAmpC). Methods The FOX-4 β-lactamase was purified. Steady-state kinetics, electrospray ionization mass spectrometry (ESI-MS) and ultraviolet difference (UVD) spectroscopy were conducted using the β-lactam scaffolds described. Results The Ki values for the monocyclic β-lactams against FOX-4 β-lactamase were 0.04 ± 0.01 μM (aztreonam) and 0.66 ± 0.03 μM (BAL30072), and the Ki value for the bridged monobactam BAL29880 was 8.9 ± 0.5 μM. For carbapenems, the Ki values ranged from 0.27 ± 0.05 μM (ertapenem) to 2.3 ± 0.3 μM (imipenem). ESI-MS demonstrated the formation of stable covalent adducts when the monocyclic β-lactams and carbapenems were reacted with FOX-4 β-lactamase. UVD spectroscopy suggested the appearance of different chromophoric intermediates. Conclusions Monocyclic β-lactam and carbapenem antibiotics are effective mechanism-based inhibitors of FOX-4 β-lactamase, a clinically important pmAmpC, and provide stimulus for the development of new inhibitors to inactivate plasmidic and chromosomal class C β-lactamases. PMID:24235094

Cross-Reactivity among Beta-Lactams.

PubMed

Romano, Antonino; Gaeta, Francesco; Arribas Poves, Maria Francisca; Valluzzi, Rocco Luigi

2016-03-01

Penicillins and cephalosporins are the major classes of beta-lactam (BL) antibiotics in use today and one of the most frequent causes of hypersensitivity reactions to drugs. Monobactams, carbapenems, oxacephems, and beta-lactamase inhibitors constitute the four minor classes of BLs. This review takes into account mainly the prospective studies which evaluated cross-reactivity among BLs in subjects with a well-demonstrated hypersensitivity to a certain class of BLs by performing allergy tests with alternative BLs and, in case of negative results, administering them. In subjects with either IgE-mediated or T-cell-mediated hypersensitivity, cross-reactivity among BLs, particularly among penicillins and among cephalosporins, as well as between penicillins and cephalosporins, seems to be mainly related to structural similarities among their side-chain determinants. Specifically, in penicillin-allergic subjects, cross-reactivity between penicillins and cephalosporins may exceed 30% when they are administered cephalosporins with identical side chains to those of responsible penicillins. In these subjects, a few prospective studies have demonstrated a rate of cross-reactivity between penicillins and both carbapenems and aztreonam lower than 1%. With regard to subjects with an IgE-mediated hypersensitivity to cephalosporins, in a single study, about 25% of the 98 subjects with such hypersensitivity had positive results to penicillins, 3% to aztreonam, 2% to imipenem/cilastatin, and 1% to meropenem. The cross-reactivity related to the selective recognition of the BL ring by IgE or T lymphocytes, which entails positive responses to all BLs tested, appears to be exceptional. Some studies concerning cross-reactivity among BLs have found patterns of allergy-test positivity which cannot be explained by either the common BL ring or by similar or identical side chains, thus indicating the possibility of coexisting sensitivities to different BLs because of prior exposures to them.

TLA-1: a New Plasmid-Mediated Extended-Spectrum β-Lactamase from Escherichia coli

PubMed Central

Silva, J.; Aguilar, C.; Ayala, G.; Estrada, M. A.; Garza-Ramos, U.; Lara-Lemus, R.; Ledezma, L.

2000-01-01

Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two β-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation from E. coli R170 to E. coli J53-2. The transferred plasmid, RZA92, which encoded a single β-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 β-lactamase (pI 9.0) was cloned from the transconjugant by transformation to E. coli DH5α. Sequencing of the blaTLA-1 gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A β-lactamases: 70SXXK, 130SDN, and 234KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A β-lactamase from Chryseobacterium (Flavobacterium) meningosepticum; 48.8% identity with the VEB-1 class A β-lactamase from E. coli; 40 to 42% identity with CblA of Bacteroides uniformis, PER-1 of Pseudomonas aeruginosa, and PER-2 of Salmonella typhimurium; and 39% identity with CepA of Bacteroides fragilis. The partially purified TLA-1 β-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum β-lactamase of Ambler class A. PMID:10722503

TLA-1: a new plasmid-mediated extended-spectrum beta-lactamase from Escherichia coli.

PubMed

Silva, J; Aguilar, C; Ayala, G; Estrada, M A; Garza-Ramos, U; Lara-Lemus, R; Ledezma, L

2000-04-01

Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two beta-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation from E. coli R170 to E. coli J53-2. The transferred plasmid, RZA92, which encoded a single beta-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 beta-lactamase (pI 9.0) was cloned from the transconjugant by transformation to E. coli DH5alpha. Sequencing of the bla(TLA-1) gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A beta-lactamases: (70)SXXK, (130)SDN, and (234)KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A beta-lactamase from Chryseobacterium (Flavobacterium) meningosepticum; 48.8% identity with the VEB-1 class A beta-lactamase from E. coli; 40 to 42% identity with CblA of Bacteroides uniformis, PER-1 of Pseudomonas aeruginosa, and PER-2 of Salmonella typhimurium; and 39% identity with CepA of Bacteroides fragilis. The partially purified TLA-1 beta-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum beta-lactamase of Ambler class A.

Antibiotic susceptibility survey of Neisseria gonorrhoeae in Thailand.

PubMed Central

Clendennen, T E; Echeverria, P; Saengeur, S; Kees, E S; Boslego, J W; Wignall, F S

1992-01-01

The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending sexually transmitted disease clinics in Cholburi and Bangkok, Thailand, were determined by agar dilution. Some 28.2% of isolates produced beta-lactamase. A total of 97.9% of beta-lactamase-positive and 51% of beta-lactamase-negative isolates tested were resistant to penicillin (MICs, greater than or equal to 2 micrograms/ml), 70% of isolates tested were resistant to tetracycline (MICs, greater than or equal to 2 micrograms/ml), and 91% of isolates tested were susceptible to spectinomycin (MICs, less than or equal to 64 micrograms/ml). The MICs for 90% of isolates for the other drugs tested were 2 micrograms/ml for erythromycin, 2 micrograms/ml for cefoxitin, 1 micrograms/ml for cefuroxime, 0.125 micrograms/ml for cefpodoxime, 0.06 micrograms/ml for cefotaxime, 0.25 micrograms/ml for ceftazidime, 0.03 micrograms/ml for ceftizoxime, 0.03 micrograms/ml for ceftriaxone, 0.03 micrograms/ml for cefixime, 0.06 micrograms/ml for aztreonam, 0.008 micrograms/ml for ciprofloxacin, 0.125 micrograms/ml for norfloxacin, and 0.075 micrograms/ml for ofloxacin. Fewer than 1.5% of isolates were resistant to the extended-spectrum cephalosporins tested. Some 0.3% or fewer isolates were resistant to broad-spectrum cephalosporins, fluoroquinolones, or the monobactam aztreonam. Antibiotic resistance among N. gonorrhoeae isolates from Cholburi and Bangkok in May 1990 appeared to be primarily limited to penicillin and tetracycline, which are no longer used to control gonorrhea. Spectinomycin, which has been in general use against gonorrhea in Thailand since 1983, has dwindling utility, with resistance at a level of 8.9%. PMID:1416851

A resurgence of β-lactamase inhibitor combinations effective against multidrug-resistant Gram-negative pathogens.

PubMed

Bush, Karen

2015-11-01

β-Lactamase inhibitors (BLIs) have played an important role in combatting β-lactam resistance in Gram-negative bacteria, but their effectiveness has diminished with the evolution of diverse and deleterious varieties of β-lactamases. In this review, a new generation of BLIs and inhibitor combinations is presented, describing epidemiological information, pharmacodynamic studies, resistance identification and current clinical status. Novel serine BLIs of major interest include the non-β-lactams of the diazabicyclo[3.2.1]octanone (DBO) series. The DBOs avibactam, relebactam and RG6080 inhibit most class A and class C β-lactamases, with selected inhibition of class D enzymes by avibactam. The novel boronic acid inhibitor RPX7009 has a similar inhibitory profile. All of these inhibitors are being developed in combinations that are targeting primarily carbapenemase-producing Gram-negative pathogens. Two BLI combinations (ceftolozane/tazobactam and ceftazidime/avibactam) were recently approved by the US Food and Drug Administration (FDA) under the designation of a Qualified Infectious Disease Product (QIDP). Other inhibitor combinations that have at least completed phase 1 clinical trials are ceftaroline fosamil/avibactam, aztreonam/avibactam, imipenem/relebactam, meropenem/RPX7009 and cefepime/AAI101. Although effective inhibitor combinations are in development for the treatment of infections caused by Gram-negative bacteria with serine carbapenemases, better options are still necessary for pathogens that produce metallo-β-lactamases (MBLs). The aztreonam/avibactam combination demonstrates inhibitory activity against MBL-producing enteric bacteria owing to the stability of the monobactam to these enzymes, but resistance is still an issue for MBL-producing non-fermentative bacteria. Because all of the inhibitor combinations are being developed as parenteral drugs, an orally bioavailable combination would also be of interest. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

A multicenter surveillance of antimicrobial resistance in Serratia marcescens in Taiwan.

PubMed

Liou, Bo-Huang; Duh, Ruay-Wang; Lin, Yi-Tsung; Lauderdale, Tsai-Ling Yang; Fung, Chang-Phone

2014-10-01

Serratia marcescens is an important nosocomial pathogen and the characteristic property of resistance conferred by extended-spectrum beta-lactamase or a novel AmpC cephalosporinase was not unusual in Taiwan. This study investigated the trends in antimicrobial resistance in S. marcescens from a nationwide surveillance in Taiwan. S. marcescens isolates were collected biennially between 2002 and 2010 from medical centers and regional hospitals throughout Taiwan, as part of the Taiwan Surveillance of Antimicrobial Resistance program. Minimal inhibitory concentrations were determined by the Clinical and Laboratory Standards Institute reference broth microdilution method. A total of 403 nonduplicate S. marcescens isolates were collected, mostly from respiratory samples (157, 39.0%), followed by the urinary tract samples (90, 22.3%). Overall, 99.3% isolates were susceptible to imipenem, 93.8% to ceftazidime, 89.2% to minocycline, 87.8% to amikacin, 86.8% to cefepime, 82.9% to aztreonam, 73.2% to ceftriaxone, 72.7% to levofloxacin, 63.8% to ciprofloxacin, 60.8% to trimethoprim/sulfamethoxazole (TMP/SMX), and 59.6% to gentamicin. A significantly increased susceptibility rate after 2004 was observed for the following antibiotics: amikacin (73.8% vs. 97.1%), gentamicin (40.0% vs. 72.4%), ciprofloxacin (53.8% vs. 70.4%), ceftriaxone (53.8% vs. 86.0%), cefepime (74.4% vs. 95.1%), aztreonam (72.5% vs. 89.7%), and TMP/SMX (41.3% vs. 73.7%). In this 8-year study, the susceptibility of S. marcescens to ceftazidime and imipenem remained consistently high in Taiwan. S. marcescens isolates demonstrated relatively higher resistance to ciprofloxacin and levofloxacin, and therefore continued surveillance of antimicrobial resistance, especially for fluoroquinolone, is warranted. Copyright © 2013. Published by Elsevier B.V.

Multidrug and heavy metal-resistant Raoultella planticola isolated from surface water.

PubMed

Koc, Serkan; Kabatas, Burak; Icgen, Bulent

2013-08-01

A surface water isolate of Raoultella sp. having both multidrug- and multimetal-resistant ability was isolated and identified as Raoultella planticola. R. planticola displayed resistance to 15 drugs like ampicillin, amoxicillin/clavulanic acid, aztreonam, erythromycin, imipenem, oxacillin, pefloxacin, penicillin, piperacillin, piperacillin/tazobactam, rifampin, sulbactam/cefoperazone, ticarsillin, ticarsillin/clavulanic acid, vancomycin, and to 11 heavy metals like aluminum, barium, copper, iron, lead, lithium, manganese, nickel, silver, strontium, and tin. The multidrug and multi-metal-resistant R. planticola may remain present in the environment for a long time. Due to a possible health risk of these pathogenic bacteria, a need exists for an accurate assessment of their acquired resistance to multiple drugs and metals.

Inhibition by Avibactam and Clavulanate of the β-Lactamases KPC-2 and CTX-M-15 Harboring the Substitution N132G in the Conserved SDN Motif.

PubMed

Ourghanlian, Clément; Soroka, Daria; Arthur, Michel

2017-03-01

The substitution N 132 G in the SDN motif of class A β-lactamases from rapidly growing mycobacteria was previously shown to impair their inhibition by avibactam but to improve the stability of acyl-enzymes formed with clavulanate. The same substitution was introduced in KPC-2 and CTX-M-15 to assess its impact on β-lactamases from Enterobacteriaceae and evaluate whether it may lead to resistance to the ceftazidime-avibactam combination. Kinetic parameters for the inhibition of the β-lactamases by avibactam and clavulanate were determined by spectrophotometry using nitrocefin as the substrate. The substitution N 132 G impaired (>1,000-fold) the efficacy of carbamylation of KPC-2 and CTX-M-15 by avibactam. The substitution improved the inhibition of KPC-2 by clavulanate due to reduced deacylation, whereas the presence or absence of N 132 G resulted in the inhibition of CTX-M-15 by clavulanate. The hydrolysis of amoxicillin and nitrocefin by KPC-2 and CTX-M-15 was moderately affected by the substitution N 132 G, but that of ceftazidime, ceftaroline, and aztreonam was drastically reduced. Isogenic strains producing KPC-2 and CTX-M-15 were constructed to assess the impact of the substitution N 132 G on the antibacterial activities of β-lactam-inhibitor combinations. For amoxicillin, the substitution resulted in resistance and susceptibility for avibactam and clavulanate, respectively. For ceftazidime, ceftaroline, and aztreonam, the negative impact of the substitution on β-lactamase activity prevented resistance to the β-lactam-avibactam combinations. In conclusion, the N 132 G substitution has profound effects on the substrate and inhibition profiles of class A β-lactamases, which are largely conserved in distantly related enzymes. Fortunately, the substitution does not lead to resistance to the ceftazidime-avibactam combination. Copyright © 2017 American Society for Microbiology.

Novel Carbapenem-Hydrolyzing β-Lactamase, KPC-1, from a Carbapenem-Resistant Strain of Klebsiella pneumoniae

PubMed Central

Yigit, Hesna; Queenan, Anne Marie; Anderson, Gregory J.; Domenech-Sanchez, Antonio; Biddle, James W.; Steward, Christine D.; Alberti, Sebastian; Bush, Karen; Tenover, Fred C.

2001-01-01

A Klebsiella pneumoniae isolate showing moderate to high-level imipenem and meropenem resistance was investigated. The MICs of both drugs were 16 μg/ml. The β-lactamase activity against imipenem and meropenem was inhibited in the presence of clavulanic acid. The strain was also resistant to extended-spectrum cephalosporins and aztreonam. Isoelectric focusing studies demonstrated three β-lactamases, with pIs of 7.2 (SHV-29), 6.7 (KPC-1), and 5.4 (TEM-1). The presence of blaSHV and blaTEM genes was confirmed by specific PCRs and DNA sequence analysis. Transformation and conjugation studies with Escherichia coli showed that the β-lactamase with a pI of 6.7, KPC-1 (K. pneumoniae carbapenemase-1), was encoded on an approximately 50-kb nonconjugative plasmid. The gene, blaKPC-1, was cloned in E. coli and shown to confer resistance to imipenem, meropenem, extended-spectrum cephalosporins, and aztreonam. The amino acid sequence of the novel carbapenem-hydrolyzing β-lactamase, KPC-1, showed 45% identity to the pI 9.7 carbapenem-hydrolyzing β-lactamase, Sme-1, from Serratia marcescens S6. Hydrolysis studies showed that purified KPC-1 hydrolyzed not only carbapenems but also penicillins, cephalosporins, and monobactams. KPC-1 had the highest affinity for meropenem. The kinetic studies also revealed that clavulanic acid and tazobactam inhibited KPC-1. An examination of the outer membrane proteins of the parent K. pneumoniae strain demonstrated that the strain does not express detectable levels of OmpK35 and OmpK37, although OmpK36 is present. We concluded that carbapenem resistance in K. pneumoniae strain 1534 is mainly due to production of a novel Bush group 2f, class A, carbapenem-hydrolyzing β-lactamase, KPC-1, although alterations in porin expression may also play a role. PMID:11257029

[Epidemiologic and therapeutic study on gonorrheal infections--one shot therapy by aztreonam].

PubMed

Kumamoto, Y; Sakai, S; Tamate, H; Gohro, T; Inoke, T; Tabata, S; Tanda, H; Kato, S; Igawa, K; Tazuki, J

1985-11-01

A clinical study of a new monocyclic beta-lactam antibiotic, AZTREONAM (hereafter referred to as AZT) for gonorrheal infections as well as epidemiologic study of gonorrheal infections were made Epidemiology: There was a reflection of the increasing sexual activity of the younger generation; both male and female patients in their twenties were most frequent (male 49.5%, female 43.7%) and the percent of teen age patients was 15.1% (male) and 34.4% (female). Forty two strains (17.2%) out of 244 clinically isolated gonococci were PPNG. Residue of serious secretion was observed in a little less than 20% suggesting a complication by Chlamydia trachomatis. Clinical Result: One shot (1-2 g) therapy by AZT was given to 244 gonorrheal infection cases (212 urethritis cases of males. 32 cervicitis cases of females) with the following highly effective rate. Although beta-lactamase producing MIC of AZT at 10(6) CFU/ml showed a peak of 0.025 microgram/ml and ranged between less than 0.0125 microgram/ml to 0.2 microgram/ml. The time required for the elimination of gonococci was studied by the administration of 1 g and 2 g AZT. Gonococci became extinct in 1-8 hours or 4-4.5 hours on average. The difference between n 1 g and 2 g was scarcely observed. Clinical effect of 1 g one shot and 2 g one shot AZT was examined on the 3rd treatment day for 244 male and females cases. The effective rate was high; 90.7% by 1 g, 97.1% by 2 g for male urethritis, 100% by 1 g also by 2 g for female cervicitis. This therapeutic efficacy was kept even in PPNG, isolated cases. There were two side effects (0.8%), one case each of numbness and, redness and swelling of both hands, out of 244 cases, but both of them were minor ones without clinical complication.

Evaluation of Pharmacodynamic Interactions Between Telavancin and Aztreonam or Piperacillin/Tazobactam Against Pseudomonas aeruginosa, Escherichia coli and Methicillin-Resistant Staphylococcus aureus.

PubMed

Yim, Juwon; Smith, Jordan R; Barber, Katie E; Hallesy, Jessica A; Rybak, Michael J

2016-09-01

In clinical trials comparing telavancin (TLV) with vancomycin for treatment of hospital-acquired pneumonia, TLV demonstrated lower clinical cure rates than vancomycin in patients who had mixed gram-positive and -negative infections and were concomitantly treated with either aztreonam (ATM) or piperacillin/tazobactam (PTZ). Here, we investigated therapeutic interactions between TLV and ATM or PTZ in an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model under simulated reduced renal function conditions. In vitro one-compartment PK/PD models were run over 96 h simulating TLV 10 mg/kg every 48 h, ATM 500 mg every 8 h and PTZ continuous infusion 13.5 g over 24 h alone and in combination against P. aeruginosa, E. coli and methicillin-resistant S. aureus (MRSA). The efficacy of antimicrobials was evaluated by plotting time-kill curves and calculating the reduction in log10 cfu/ml over 96 h. Against both MRSA strains, TLV was rapidly bactericidal at 4 h and maintained its activity over 96 h with no observed antagonism by either ATM or PTZ. PTZ maintained bacteriostatic and bactericidal activities against E. coli ATCC 25922 and clinical strain R1022 at 96 h, whereas both strains regrew as soon as 24 h in ATM models. Against P. aeruginosa ATCC 27853, regrowth was noted at 24 h in models simulating ATM and PTZ. The addition of TLV to ATM or PTZ had no appreciable impact on activity against the two E. coli strains and P. aeruginosa strain. The combinations of TLV and either ATM or PTZ did not demonstrate any antagonistic activity. Clinical variables and patient characteristics should be further explored to determine possible reasons for discrepancies in outcomes. Theravance Biopharma Antibiotics, Inc.

Antibacterial activity of BMS-180680, a new catechol-containing monobactam.

PubMed Central

Fung-Tomc, J; Bush, K; Minassian, B; Kolek, B; Flamm, R; Gradelski, E; Bonner, D

1997-01-01

The in vitro activities of a new catechol-containing monobactam, BMS-180680 (SQ 84,100), were compared to those of aztreonam, ceftazidime, imipenem, piperacillin-tazobactam, ciprofloxacin, amikacin, and trimethoprim-sulfamethoxazole. BMS-180680 was often the most active compound against many species of the family Enterobacteriaceae, with MICs at which 90% of the isolates were inhibited (MIC90s) of < or = 0.5 microg/ml for Escherichia coli, Klebsiella spp., Citrobacter diversus, Enterobacter aerogenes, Serratia marcescens, Proteus spp., and Providencia spp. BMS-180680 had moderate activities (MIC90s of 2 to 8 microg/ml) against Citrobacter freundii, Morganella morganii, Shigella spp., and non-E. aerogenes Enterobacter spp. BMS-180680 was the only antibiotic evaluated that was active against >90% of the Pseudomonas aeruginosa (MIC90, 0.25 microg/ml), Burkholderia cepacia, and Stenotrophomonas maltophilia (MIC90s, 1 microg/ml) strains tested. BMS-180680 was inactive against most strains of Pseudomonas fluorescens, Pseudomonas stutzeri, Pseudomonas diminuta, and Burkholderia pickettii. BMS-180680 was moderately active (MIC90s of 4 to 8 microg/ml) against Alcaligenes spp. and Acinetobacter lwoffii and less active (MIC90, 16 microg/ml) against Acinetobacter calcoaceticus-Acinetobacter baumanii complex. BMS-180680 lacked activity against gram-positive bacteria and anaerobic bacteria. Both tonB and cir fiu double mutants of E. coli had greatly decreased susceptibility to BMS-180680. Of the TEM, PSE, and chromosomal-encoded beta-lactamases tested, only the K1 enzyme hydrolyzed BMS-180680 to any measurable extent. Like aztreonam, BMS-180680 bound preferentially to penicillin-binding protein 3. The MICs of BMS-180680 were not influenced by the presence of hematin or 5% sheep blood in the test medium or with incubation in an atmosphere containing 5% CO2. BMS-180680 MICs obtained under strict anaerobic conditions were significantly higher than those obtained in ambient air. PMID:9145861

The Rationale and Evidence for Use of Inhaled Antibiotics to Control Pseudomonas aeruginosa Infection in Non-cystic Fibrosis Bronchiectasis

PubMed Central

2018-01-01

Abstract Non-cystic fibrosis bronchiectasis (NCFBE) is a chronic inflammatory lung disease characterized by irreversible dilation of the bronchi, symptoms of persistent cough and expectoration, and recurrent infective exacerbations. The prevalence of NCFBE is on the increase in the United States and Europe, but no licensed therapies are currently available for its treatment. Although there are many similarities between NCFBE and cystic fibrosis (CF) in terms of respiratory symptoms, airway microbiology, and disease progression, there are key differences, for example, in response to treatment, suggesting differences in pathogenesis. This review discusses possible reasons underlying differences in response to inhaled antibiotics in people with CF and NCFBE. Pseudomonas aeruginosa infections are associated with the most severe forms of bronchiectasis. Suboptimal levels of antibiotics in the lung increase the mutation frequency of P. aeruginosa and lead to the development of mucoid strains characterized by formation of a protective polysaccharide biofilm. Mucoid strains of P. aeruginosa are associated with a chronic infection stage, requiring long-term antibiotic therapy. Inhaled antibiotics provide targeted delivery to the lung with minimal systemic toxicity and adverse events compared with oral/intravenous routes of administration, and they could be alternative treatment options to help address some of the treatment challenges in the management of severe cases of NCFBE. This review provides an overview of completed and ongoing trials that evaluated inhaled antibiotic therapy for NCFBE. Recently, several investigators conducted phase 3 randomized controlled trials with inhaled aztreonam and ciprofloxacin in patients with NCFBE. While the aztreonam trial results were not associated with significant clinical benefit in NCFBE, initial results reported from the inhaled ciprofloxacin (dry powder for inhalation and liposome-encapsulated/dual-release formulations) trials hold promise. A more targeted approach could identify specific populations of NCFBE patients who benefit from inhaled antibiotics. PMID:29077527

Can Ceftazidime-Avibactam and Aztreonam Overcome β-Lactam Resistance Conferred by Metallo-β-Lactamases in Enterobacteriaceae?

PubMed

Marshall, Steven; Hujer, Andrea M; Rojas, Laura J; Papp-Wallace, Krisztina M; Humphries, Romney M; Spellberg, Brad; Hujer, Kristine M; Marshall, Emma K; Rudin, Susan D; Perez, Federico; Wilson, Brigid M; Wasserman, Ronald B; Chikowski, Linda; Paterson, David L; Vila, Alejandro J; van Duin, David; Kreiswirth, Barry N; Chambers, Henry F; Fowler, Vance G; Jacobs, Michael R; Pulse, Mark E; Weiss, William J; Bonomo, Robert A

2017-04-01

Based upon knowledge of the hydrolytic profile of major β-lactamases found in Gram-negative bacteria, we tested the efficacy of the combination of ceftazidime-avibactam (CAZ-AVI) with aztreonam (ATM) against carbapenem-resistant enteric bacteria possessing metallo-β-lactamases (MBLs). Disk diffusion and agar-based antimicrobial susceptibility testing were initially performed to determine the in vitro efficacy of a unique combination of CAZ-AVI and ATM against 21 representative Enterobacteriaceae isolates with a complex molecular background that included bla IMP , bla NDM , bla OXA-48 , bla CTX-M , bla AmpC , and combinations thereof. Time-kill assays were conducted, and the in vivo efficacy of this combination was assessed in a murine neutropenic thigh infection model. By disk diffusion assay, all 21 isolates were resistant to CAZ-AVI alone, and 19/21 were resistant to ATM. The in vitro activity of CAZ-AVI in combination with ATM against diverse Enterobacteriaceae possessing MBLs was demonstrated in 17/21 isolates, where the zone of inhibition was ≥21 mm. All isolates demonstrated a reduction in CAZ-AVI agar dilution MICs with the addition of ATM. At 2 h, time-kill assays demonstrated a ≥4-log 10 -CFU decrease for all groups that had CAZ-AVI with ATM (8 μg/ml) added, compared to the group treated with CAZ-AVI alone. In the murine neutropenic thigh infection model, an almost 4-log 10 -CFU reduction was noted at 24 h for CAZ-AVI (32 mg/kg every 8 h [q8h]) plus ATM (32 mg/kg q8h) versus CAZ-AVI (32 mg/kg q8h) alone. The data presented herein require us to carefully consider this new therapeutic combination to treat infections caused by MBL-producing Enterobacteriaceae . Copyright © 2017 American Society for Microbiology.

In vivo efficacy of human simulated regimens of carbapenems and comparator agents against NDM-1-producing Enterobacteriaceae.

PubMed

Wiskirchen, Dora E; Nordmann, Patrice; Crandon, Jared L; Nicolau, David P

2014-01-01

Doripenem and ertapenem have demonstrated efficacy against several NDM-1-producing isolates in vivo, despite having high MICs. In this study, we sought to further characterize the efficacy profiles of humanized regimens of standard (500 mg given every 8 h) and high-dose, prolonged infusion of doripenem (2 g given every 8 h, 4-h infusion) and 1 g of ertapenem given intravenously every 24 h and the comparator regimens of ceftazidime at 2 g given every 8 h (2-h infusion), levofloxacin at 500 mg every 24 h, and aztreonam at 2 g every 6 h (1-h infusion) against a wider range of isolates in a murine thigh infection model. An isogenic wild-type strain and NDM-1-producing Klebsiella pneumoniae and eight clinical NDM-1-producing members of the family Enterobacteriaceae were tested in immunocompetent- and neutropenic-mouse models. The wild-type strain was susceptible to all of the agents, while the isogenic NDM-1-producing strain was resistant to ceftazidime, doripenem, and ertapenem. Clinical NDM-1-producing strains were resistant to nearly all five of the agents (two were susceptible to levofloxacin). In immunocompetent mice, all of the agents produced ≥1-log10 CFU reductions of the isogenic wild-type and NDM-1-producing strains after 24 h. Minimal efficacy of ceftazidime, aztreonam, and levofloxacin against the clinical NDM-1-producing strains was observed. However, despite in vitro resistance, ≥1-log10 CFU reductions of six of eight clinical strains were achieved with high-dose, prolonged infusion of doripenem and ertapenem. Slight enhancements of doripenem activity over the standard doses were obtained with high-dose, prolonged infusion for three of the four isolates tested. Similar efficacy observations were noted in neutropenic mice. These data suggest that carbapenems are a viable treatment option for infections caused by NDM-1-producing Enterobacteriaceae.

Performance of Vitek 2 in Antimicrobial Susceptibility Testing of Pseudomonas aeruginosa Isolates with Different Mechanisms of β-Lactam Resistance▿

PubMed Central

Mazzariol, Annarita; Aldegheri, Marco; Ligozzi, Marco; Lo Cascio, Giuliana; Koncan, Raffaella; Fontana, Roberta

2008-01-01

A total of 78 isolates of Pseudomonas aeruginosa grouped according to the phenotype for ceftazidime and imipenem susceptibility/resistance were used to assess the accuracy of the Vitek 2 system in antimicrobial susceptibility testing. Comparisons were made with a MIC gradient test for piperacillin-tazobactam, ceftazidime, aztreonam, imipenem, meropenem, gentamicin, and ciprofloxacin. For the total of 546 isolate-antimicrobial combinations tested, the category agreement was 83.6%, with 2.0, 1.6, and 12.8% very major, major, and minor errors, respectively. Vitek 2 accuracy was influenced differently by the mechanism responsible for resistance, and interpretation of the results in relation to phenotype could improve the performance of the system. PMID:18434562

[Prevalence of metallo-beta-lactamase in carbapenem resistant Pseudomonas aeruginosa at a university hospital of Buenos Aires City].

PubMed

Pagniez, G; Radice, M; Cuirolo, A; Rodríguez, O; Rodríguez, H; Vay, C; Famiglietti, A; Gutkind, G

2006-01-01

The present study was conducted to estimate the prevalence of metallo-beta-lactamases in 91 consecutive carbapenem resistant Pseudomonas aeruginosa isolates, recovered from inpatients at Hospital de Clínicas in Buenos Aires. Both, phenotypic and genotypic methods detected the presence of carbapenemases in 10 (11%) isolates, corresponding to VIM-11 in 7/10 and VIM-2 in the others. Codifying genes were all included in class 1 integrons, upstream genes coding for aminoglycoside modifying enzymes. One hundred percent sensitivity and specificity was achieved by the metallo-beta-lactamases phenotypic screening method using EDTA (1 micromol) disks in the Pseudomonas aeruginosa isolates included in this study. Sensitivity to aztreonam in carbapenem resistant isolates was suspicious of the presence of these enzymes.

Role of ser-237 in the substrate specificity of the carbapenem-hydrolyzing class A beta-lactamase Sme-1.

PubMed

Sougakoff, W; Naas, T; Nordmann, P; Collatz, E; Jarlier, V

1999-08-17

The role of the serine residue found at position 237 in the carbapenemase Sme-1 has been investigated by constructing a mutant in which Ser-237 was replaced by an alanine. The S237A mutant showed a catalytic behavior against penicillins and aztreonam very similar to that of Sme-1. By contrast, S237A was characterized by a reduced catalytic efficiency against cephems, such as cephalothin and cephaloridine. In addition, the weak activity of Sme-1 against the cephamycin cefoxitin was hardly detectable with the mutant enzyme. Finally, the Ser-237-->Ala mutation resulted in a marked decrease in catalytic activity against imipenem, showing that Ser-237 contributes to the carbapenemase activity of the class A beta-lactamase Sme-1.

PER-8, a Novel Extended-Spectrum β-Lactamase PER Variant, from an Acinetobacter baumannii Clinical Isolate in Nepal.

PubMed

Tada, Tatsuya; Shrestha, Shovita; Shimada, Kayo; Ohara, Hiroshi; Sherchand, Jeevan B; Pokhrel, Bharat M; Kirikae, Teruo

2017-03-01

A novel PER-type extended-spectrum β-lactamase, PER-8, was identified in an Acinetobacter baumannii clinical isolate obtained in Nepal. The amino acid sequence of PER-8 has a substitution at position 39 (Gly to Glu) compared with that of PER-7. The k cat / K m ratio of PER-8 for aztreonam was lower than that of PER-7, while the k cat / K m ratio of PER-8 for imipenem was higher than that of PER-7. The genomic environment surrounding bla PER-8 was intI1 bla PSE-1 qacEDI sulI IS CR1-bla PER-8 gts sulI orfX on a 100-kb plasmid. Copyright © 2017 American Society for Microbiology.

Description of IMP-31, a novel metallo-β-lactamase found in an ST235 Pseudomonas aeruginosa strain in Western Germany.

PubMed

Pfennigwerth, Niels; Geis, Gabriele; Gatermann, Sören G; Kaase, Martin

2015-07-01

The objective of this study was to characterize a novel IMP-type metallo-β-lactamase (MBL) found in an MDR clinical isolate of Pseudomonas aeruginosa. The P. aeruginosa isolate NRZ-00156 was recovered from an inguinal swab from a patient hospitalized in Western Germany and showed high MICs of carbapenems. MBL production was analysed by Etest for MBLs, an EDTA combined disc test and an EDTA bioassay. Typing of the isolate was performed by MLST. Genetic characterization of the new blaIMP gene was performed by sequencing the PCR products. A phylogenetic tree was constructed. The novel blaIMP gene was expressed in Escherichia coli TOP10 and the enzyme was subjected to biochemical characterization. The P. aeruginosa isolate NRZ-00156 expressed the ST235 allelic profile and was resistant to all the β-lactams tested except aztreonam. The isolate was positive for MBL production and harboured a new IMP allele, blaIMP-31, located on a disrupted class I integron [also carrying the blaOXA-35, aac(6')-Ib, aac(3)-Ic and aphA15 genes]. Its closest relative was IMP-35, with 96.7% amino acid identity. Expression of blaIMP-31 demonstrated that E. coli TOP10 producing IMP-31 had elevated resistance to all the β-lactams tested except aztreonam. Kinetic data were obtained for both IMP-31 and IMP-1. In comparison with IMP-1, IMP-31 showed weaker hydrolytic activity against all the β-lactams tested, which resulted from lower kcat values. The characterization of the new IMP-type gene blaIMP-31 from an ST235 P. aeruginosa isolate indicates an ongoing spread of highly divergent IMP-type carbapenemases in clinical P. aeruginosa strains and highlights the continuous need for the prevention of nosocomial infections caused by MDR Gram-negative bacteria. © 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.

The occurrence of ESBL-producing Escherichia coli carrying aminoglycoside resistance genes in urinary tract infections in Saudi Arabia.

PubMed

Alyamani, Essam J; Khiyami, Anamil M; Booq, Rayan Y; Majrashi, Majed A; Bahwerth, Fayez S; Rechkina, Elena

2017-01-06

The infection and prevalence of extended-spectrum β-lactamases (ESBLs) is a worldwide problem, and the presence of ESBLs varies between countries. In this study, we investigated the occurrence of plasmid-mediated ESBL/AmpC/carbapenemase/aminoglycoside resistance gene expression in Escherichia coli using phenotypic and genotypic techniques. A total of 58 E. coli isolates were collected from hospitals in the city of Makkah and screened for the production of ESBL/AmpC/carbapenemase/aminoglycoside resistance genes. All samples were subjected to phenotypic and genotypic analyses. The antibiotic susceptibility of the E. coli isolates was determined using the Vitek-2 system and the minimum inhibitory concentration (MIC) assay. Antimicrobial agents tested using the Vitek 2 system and MIC assay included the expanded-spectrum (or third-generation) cephalosporins (e.g., cefoxitin, cefepime, aztreonam, cefotaxime, ceftriaxone, and ceftazidime) and carbapenems (meropenem and imipenem). Reported positive isolates were investigated using genotyping technology (oligonucleotide microarray-based assay and PCR). The genotyping investigation was focused on ESBL variants and the AmpC, carbapenemase and aminoglycoside resistance genes. E. coli was phylogenetically grouped, and the clonality of the isolates was studied using multilocus sequence typing (MLST). Our E. coli isolates exhibited different levels of resistance to ESBL drugs, including ampicillin (96.61%), cefoxitin (15.25%), ciprofloxacin (79.66%), cefepime (75.58%), aztreonam (89.83%), cefotaxime (76.27%), ceftazidime (81.36%), meropenem (0%) and imipenem (0%). Furthermore, the distribution of ESBL-producing E. coli was consistent with the data obtained using an oligonucleotide microarray-based assay and PCR genotyping against genes associated with β-lactam resistance. ST131 was the dominant sequence type lineage of the isolates and was the most uropathogenic E. coli lineage. The E. coli isolates also carried aminoglycoside resistance genes. The evolution and prevalence of ESBL-producing E. coli may be rapidly accelerating in Saudi Arabia due to the high visitation seasons (especially to the city of Makkah). The health authority in Saudi Arabia should monitor the level of drug resistance in all general hospitals to reduce the increasing trend of microbial drug resistance and the impact on patient therapy.

Effects of Asp-179 mutations in TEMpUC19 beta-lactamase on susceptibility to beta-lactams.

PubMed Central

Vakulenko, S B; Tóth, M; Taibi, P; Mobashery, S; Lerner, S A

1995-01-01

To examine the effect of disruption of the salt bridge (between Arg-164 and Asp-179 [numbering of Ambler et al. (Biochem J. 267:269-272, 1991)]) that anchors the conserved omega-loop in class A beta-lactamases, we obtained mutant enzymes with each of the 19 other amino acid residues replacing Asp-179 in the TEM beta-lactamase encoded by pUC19 and studied the level of resistance to various beta-lactams conferred by each enzyme. All mutations of Asp-179 compromised the level of resistance to ampicillin, but most of them enhanced resistance to ceftazidime. In contrast, mutations of Asp-179 generally impaired the low levels of resistance to cefepime and aztreonam. One might expect to find clinical isolates with mutant TEM beta-lactamases with replacements of Asp-179 that express an expanded spectrum of resistance to beta-lactams including ceftazidime. PMID:7486939

[Inhaled treatments in cystic fibrosis: what's new in 2013?].

PubMed

Dubus, J-C; Bassinet, L; Chedevergne, F; Delaisi, B; Desmazes-Dufeu, N; Reychler, G; Vecellio, L

2014-04-01

In the past few years some new inhaled drugs and inhalation devices have been proposed for the treatment of cystic fibrosis. Breath-controlled nebulizers allow increased pulmonary deposition, with a lower variability and a shorter delivery time. The new dry powder formulations of tobramycin, colistine and mannitol require a change in the inhalation technique which must be slow and deep. In the field of the inhaled mucolytic drugs, hypertonic saline and mannitol have an indication in some patients. With regard to antibiotics, dry-powder tobramycin and colistine can be substituted for the same drug delivered by nebulization. Nebulized aztreonam needs more studies to determine its place. These new treatments represent a definite advance for cystic fibrosis patients and need to be known by all practitioners. Their position in our therapeutic arsenal remains to be accurately defined. Copyright © 2013 SPLF. Published by Elsevier Masson SAS. All rights reserved.

The rapid spread of carbapenem-resistant Enterobacteriaceae

PubMed Central

Potter, Robert F.; D’Souza, Alaric W.; Dantas, Gautam

2016-01-01

Carbapenems, our one-time silver bullet for multidrug resistant bacterial infections, are now threatened by widespread dissemination of carbapenem-resistant Enterobacteriaceae (CRE). Successful expansion of Enterobacteriaceae clonal groups and frequent horizontal gene transfer of carbapenemase expressing plasmids are causing increasing carbapenem resistance. Recent advances in genetic and phenotypic detection facilitate global surveillance of CRE diversity and prevalence. In particular, whole genome sequencing enabled efficient tracking, annotation, and study of genetic elements colocalized with carbapenemase genes on chromosomes and on plasmids. Improved characterization helps detail the co-occurrence of other antibiotic resistance genes in CRE isolates and helps identify pan-drug resistance mechanisms. The novel β-lactamase inhibitor, avibactam, combined with ceftazidime or aztreonam, is a promising CRE treatment compared to current colistin or tigecycline regimens. To halt increasing CRE-associated morbidity and mortality, we must continue quality, cooperative monitoring and urgently investigate novel treatments. PMID:27912842

Cloning and sequence of the gene encoding a cefotaxime-hydrolyzing class A beta-lactamase isolated from Escherichia coli.

PubMed Central

Ishii, Y; Ohno, A; Taguchi, H; Imajo, S; Ishiguro, M; Matsuzawa, H

1995-01-01

Escherichia coli TUH12191, which is resistant to piperacillin, cefazolin, cefotiam, ceftizoxime, cefuzonam, and aztreonam but is susceptible to cefoxitin, latamoxef, flomoxef, and imipenem, was isolated from the urine of a patient treated with beta-lactam antibiotics. The beta-lactamase (Toho-1) purified from the bacteria had a pI of 7.8, had a molecular weight of about 29,000, and hydrolyzed beta-lactam antibiotics such as penicillin G, ampicillin, oxacillin, carbenicillin, piperacillin, cephalothin, cefoxitin, cefotaxime, ceftazidime, and aztreonam. Toho-1 was markedly inhibited by beta-lactamase inhibitors such as clavulanic acid and tazobactam. Resistance to beta-lactams, streptomycin, spectinomycin, sulfamethoxazole, and trimethoprim was transferred by conjugational transfer from E. coli TUH12191 to E. coli ML4903, and the transferred plasmid was about 58 kbp, belonging to incompatibility group M. The cefotaxime resistance gene for Toho-1 was subcloned from the 58-kbp plasmid by transformation of E. coli MV1184. The sequence of the gene for Toho-1 was determined, and the open reading frame of the gene consisted of 873 or 876 bases (initial sequence, ATGATG). The nucleotide sequence of the gene (DDBJ accession number D37830) was found to be about 73% homologous to the sequence of the gene encoding a class A beta-lactamase produced by Klebsiella oxytoca E23004. According to the amino acid sequence deduced from the DNA sequence, the precursor consisted of 290 or 291 amino acid residues, which contained amino acid motifs common to class A beta-lactamases (70SXXK, 130SDN, and 234KTG). Toho-1 was about 83% homologous to the beta-lactamase mediated by the chromosome of K. oxytoca D488 and the beta-lactamase mediated by the plasmid of E. coli MEN-1. Therefore, the newly isolated beta-lactamase Toho-1 produced by E. coli TUH12191 is similar to beta-lactamases produced by K. oxytoca D488, K. oxytoca E23004, and E. coli MEN-1 rather than to mutants of TEM or SHV enzymes. Toho-1 has shown the highest degree of similarity to K. oxytoca class A beta-lactamase. Detailed comparison of Toho-1 with other beta-lactamases implied that replacement of Asn-276 by Arg with the concomitant substitution of Thr for Arg-244 is an important mutation in the extension of the substrate specificity. PMID:8619581

The antibiotic pipeline for multi-drug resistant gram negative bacteria: what can we expect?

PubMed

Falagas, Matthew E; Mavroudis, Andreas D; Vardakas, Konstantinos Z

2016-08-01

A real concern in the medical community is the increasing resistance of bacteria, especially that of Gram-negative types. New antibiotics are currently under clinical development, promising to tackle severe infections caused, especially, by multi-drug resistant (MDR) bacteria and broaden the armamentarium of clinicians. We searched PUBMED and GOOGLE databases. Combinations of already approved β-lactams or monobactams with new β-lactamase inhibitors [imipenem-cilastatin/MK-7655 (relebactam), meropenem/RPX7009 (vaborbactam), ceftaroline/avibactam, aztreonam/avibactam], new β-lactams (S-649266, BAL30072), aminoglycosides (plazomicin), quinolones (finafloxacin) and tetracyclines (eravacycline) were included in the review. Expert commentary: For the majority of the upcoming antibiotics the currently available data is limited to their microbiology and pharmacokinetics. Their effectiveness and safety against infections due to MDR bacteria remain to be proved. Significant issues are also the impact of these antibiotics on the human intestinal microbiota and their possible co-administration with already-known antimicrobial agents in difficult-to-treat-infections; further studies should be conducted for these objectives.

Delafloxacin: an improved fluoroquinolone developed through advanced molecular engineering.

PubMed

Bassetti, Matteo; Righi, Elda; Pecori, Davide; Tillotson, Glenn

2018-05-16

The emergence of antimicrobial resistance threatens current clinical practice across a range of infection types. Delafloxacin, a non-zwitterionic fluoroquinolone recently approved by the US FDA for the treatment of acute bacterial skin and skin structure infections, has been developed to address some of these challenges. Uniquely delafloxacin has increased intracellular penetration and enhanced antibacterial activity under acidic conditions, an environment seen in many infection sites including abscesses. Delafloxacin is active against a wide range of Gram-positive and -negative species including methicillin-resistant Staphylococcus aureus and many fluoroquinolone-resistant strains. Additionally, according to preclinical and clinical trial data, well-known adverse events related to fluoroquinolone class do not appear to occur with this new molecule. Delafloxacin has been studied in acute bacterial skin and skin structure infections with >1400 patients exposed to both intravenous and oral formulation for up to 14 days and has shown noninteriority to vancomycin with or without aztreonam. For its interesting microbiological and pharmacokinetic/pharmacodynamics characteristics and for its safety profile, delafloxacin represents a very promising option for the treatment of infections caused by multidrug-resistant pathogens.

Emerging treatment options for acute bacterial skin and skin structure infections: focus on intravenous delafloxacin

PubMed Central

Righi, Elda; Carnelutti, Alessia; Vena, Antonio; Bassetti, Matteo

2018-01-01

The increase in hospitalization due to acute bacterial skin and skin structure infections (ABSSSI) caused by resistant pathogens supports the need for new treatment options. Antimicrobial options for ABSSSI that provide broad-spectrum coverage, including gram-negative pathogens and multidrug-resistant gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are limited. Delafloxacin is a novel fluoroquinolone available as intravenous and oral formulations and is characterized by an increased efficacy in acidic environments and activity on bacterial biofilm. Delafloxacin displays enhanced in vitro activity against MRSA, and enterococci, while maintaining efficacy against gram-negative pathogens and anaerobes. Delafloxacin has been studied for the treatment of ABSSSI and respiratory infections. Phase III studies have demonstrated noninferiority of delafloxacin compared to vancomycin, linezolid, tigecycline, and the combination of vancomycin plus aztreonam in the treatment of ABSSSI. Due to its favorable pharmacokinetic characteristics, the wide spectrum of action, and the potential for sequential therapy, delafloxacin represents a promising option in the empirical and targeted treatment of ABSSSI, both in hospital- and in community-based care. PMID:29670380

Emerging treatment options for acute bacterial skin and skin structure infections: focus on intravenous delafloxacin.

PubMed

Righi, Elda; Carnelutti, Alessia; Vena, Antonio; Bassetti, Matteo

2018-01-01

The increase in hospitalization due to acute bacterial skin and skin structure infections (ABSSSI) caused by resistant pathogens supports the need for new treatment options. Antimicrobial options for ABSSSI that provide broad-spectrum coverage, including gram-negative pathogens and multidrug-resistant gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are limited. Delafloxacin is a novel fluoroquinolone available as intravenous and oral formulations and is characterized by an increased efficacy in acidic environments and activity on bacterial biofilm. Delafloxacin displays enhanced in vitro activity against MRSA, and enterococci, while maintaining efficacy against gram-negative pathogens and anaerobes. Delafloxacin has been studied for the treatment of ABSSSI and respiratory infections. Phase III studies have demonstrated noninferiority of delafloxacin compared to vancomycin, linezolid, tigecycline, and the combination of vancomycin plus aztreonam in the treatment of ABSSSI. Due to its favorable pharmacokinetic characteristics, the wide spectrum of action, and the potential for sequential therapy, delafloxacin represents a promising option in the empirical and targeted treatment of ABSSSI, both in hospital- and in community-based care.

Septic abortion presenting as a right lower trapezius abscess secondary to Bacteroides fragilis bacteraemia.

PubMed

Yamanaka, Yusuke; Shimabukuro, Akira

2017-08-21

A 43-year-old Japanese woman was evaluated in the outpatient department for right shoulder pain and fever, which began 5 days earlier. MRI of the right shoulder revealed a high-intensity area deep in the right trapezius muscle. Aspiration revealed purulent fluid, and Gram staining of the fluid showed Gram-negative bacilli. The patient was also found to be profoundly anaemic and to have a positive urine pregnancy test. On admission, we initiated intravenous ampicillin-sulbactam and aztreonam. She underwent dilatation and curettage for septic abortion and surgical drainage of the right shoulder abscess. Bacteroides fragilis was isolated from the blood, uterine aspiration and abscess samples. On hospital day 4, a whole-body CT scan revealed no other abscesses, and ampicillin-sulbactam was continued for 28 days. The patient was discharged on hospital day 29. Gram staining is an important tool for evaluating infectious aetiologies. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Carbapenem-resistant Serratia marcescens isolates producing Bush group 2f beta-lactamase (SME-1) in the United States: results from the MYSTIC Programme.

PubMed

Gales, A C; Biedenbach, D J; Winokur, P; Hacek, D M; Pfaller, M A; Jones, R N

2001-02-01

Two carbapenem (imipenem, meropenem)-resistant Serratia marcescens strains were isolated in the United States (Chicago, IL) through the 1999 MYSTIC (Meropenem Yearly Susceptibility Test Information Collection) Programme. The S. marcescens antimicrobial susceptible patterns were: susceptible to ceftriaxone, ceftazidime, and cefepime (MICs, < or = 0.25 microg/ml), and resistance to the carbapenems (imipenem and meropenem; MIC, > 32 microg/ml) and aztreonam (MIC, > = 16 microg/ml). Each S. marcescens isolate shared an identical epidemiologic type (ribotype and PFGE) and the outer membrane protein profile was also identical to those of the wild type susceptible strains from the same medical center. The PCR utilizing bla(sme-1) primers amplified a gene product that was identified as consistent with SME-1 after DNA sequencing. Imipenem and meropenem resistance due to production of carbapenem-hydrolyzing enzymes among clinical isolates is still very rare, but microbiology laboratories should be aware of these chromosomally encoded enzymes among class C beta-lactamases producing enteric bacilli such as S. marcescens and Enterobacter cloacae.

Characterization of integron-mediated antimicrobial resistance among Escherichia coli strains isolated from a captive population of Amur tigers in China.

PubMed

Xue, Yuan; Chen, Jianfei; Wang, Yulong; Zhang, Yanlong; Liu, Dan; Hua, Yuping

2013-12-01

The present study was undertaken to identify and characterize integrons and integrated resistance gene cassettes among multidrug resistant Escherichia coli isolates from a captive population of Amur tigers (Panthera tigris altaica) in China. In addition, the prevalence of antimicrobial resistance and class I integrons was assessed in E. coli strains (n = 61) isolated from a captive population of Amur tigers in Heilongjiang Amur Tiger Park, China. Among the isolates, 52.46% (32 of 61) were positive for intI1, but no isolates carried intI2 or intI3. Most isolates were susceptible to amoxicillin/clavulanic acid, aztreonam, and polymyxin B, while they also exhibited high incidence rates of resistance to ampicillin, doxycycline, chloramphenicol, tetracycline, and dihydrofolate reductase. Sequencing analysis revealed three gene cassettes, which encoded resistance to dihydrofolate reductase (dfrA15), dihydrofolate reductase (dfrA12), and adenyltransferase (aadA2). The gene cassette arrays dfrA15 (31%) and dfrA12-aadA2 (19%) were most prevalent among these isolates.

Resistance to Extended-Spectrum β-Lactamases in Salmonella from a Broiler Supply Chain

PubMed Central

Gelinski, Jane Mary Lafayette Neves; Bombassaro, Amanda; Baratto, César Milton; Vicente, Vânia Aparecida

2014-01-01

The prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae varies worldwide, however, the incidence of ESBL-producing environmental Salmonella isolates is increasing. Salmonella is still one of the most important pathogens that occur in the poultry supply chain. Therefore, this study analyzed the susceptibility of Salmonella isolates collected from a poultry supply chain to β-lactam antibiotics, and examined the phenotypes of the isolates based on enzyme-inducible AmpC β-lactamase analysis. All analysis of the putative positive isolates in the current study confirmed that 27.02% (77/285 analysis) of all ESBL tests realized with the isolates produced a profile of resistance consistent with β-lactamase production. All isolates of S. Minnesota serotype had ESBL phenotype. Aztreonam resistance was the least common amongst the Salmonella isolates, followed by ceftazidime. The presence of inducible chromosomal ESBL was detected in 14 different isolates of the 19 serotypes investigated. These results are very indicatives of the presence of ESBL genes in Salmonella isolates from a broiler supply chain, reaffirming the growing global problem of ESBL resistance. PMID:25402566

Inhaled antibiotics: the new era of personalized medicine?

PubMed

Biller, Julie A

2015-11-01

Treatment options for individuals with cystic fibrosis (CF) have improved survival significantly over the past two decades. One important treatment modality is inhaled antibiotics to treat chronic infection of the airways. This review includes those antibiotics that are currently in use, those that are in clinical trials. It also includes review of nonantibiotic antimicrobials, a growing area of investigation in CF. There are currently three inhaled antibiotics that are approved for use in patients with cystic fibrosis: tobramycin, aztreonam, and colistimethate. Tobramycin and colistimethate now are available as solution and new dry powder formulations, which are helping the treatment burden which has increased in CF. New antibiotics are in trial, although recently two did not meet primary outcomes in large clinical trials. Of particular interest is the development of nonantibiotic antimicrobials, which may allow treatment of intrinsically antibiotic resistant organisms. Inhaled antibiotics remain an important treatment option in cystic fibrosis due to chronic airway infection as a hallmark of the disease. Although there are now multiple options for treatment, improvements in this treatment class are needed to treat intrinsically resistant organisms. New formulation of antibiotics and nonantibiotic antimicrobials are being evaluated to add to our armamentarium.

New options of antibiotic combination therapy for multidrug-resistant Pseudomonas aeruginosa.

PubMed

Nakamura, I; Yamaguchi, T; Tsukimori, A; Sato, A; Fukushima, S; Matsumoto, T

2015-01-01

Several antibiotic combinations have demonstrated increased activity against multidrug-resistant Pseudomonas aeruginosa (MDRP) in vitro compared with a single antibiotic. The aim of this study was to investigate the activity against MDRP of some aminoglycosides in combination with monobactam, piperacillin (PIPC), and carbapenem. Clinical isolates of MDRP were collected between November 2010 and October 2012 from patients in Tokyo Medical University Hospital, Tokyo (1,015 beds). Our new method was designed to evaluate three concentrations around the breakpoint of each drug using the Checkerboard method. The aminoglycosides tested were amikacin (AMK), tobramycin (TOB), and arbekacin (ABK). Ciprofloxacin, PIPC, and biapenem (BIPM), which have been reported to demonstrate combination effects, were also tested. Sixty-six MDRP strains were identified from the 2,417 P. aeruginosa strains. Of the 66, 27 tested positive for metallo-β-lactamase (MBL). Aztreonam (AZT) with AMK or ABK was the most effective against MDRP. PIPC with AMK or ABK were somewhat effective. AZT with AMK or ABK were more effective against MBL-positive strains than MBL-negative strains. However, PIPC with AMK or ABK were more effective against MBL-negative strains than MBL-positive strains. Combination activities showed differences between MBL-positive and MBL-negative strains.

Etiology and antimicrobial resistance patterns in pediatric urinary tract infection.

PubMed

Wang, Jun; He, Lijiao; Sha, Jintong; Zhu, Haobo; Huang, Liqu; Zhu, Xiaojiang; Dong, Jun; Li, Guogen; Ge, Zheng; Lu, Rugang; Ma, Geng; Shi, Yaqi; Guo, Yunfei

2018-02-02

Urinary tract infection (UTI) is one of most common pediatric infections. The aim of this study was to investigate the etiology and antimicrobial resistance patterns in children hospitalized at Children's Hospital of Nanjing Medical University. We conducted a retrospective, descriptive study of all UTI from 1 January 2013 to 30 November 2016 in children discharged from Nanjing Children's Hospital. The isolated pathogens and their resistance patterns were examined using midstream urine culture. A total of 2,316 children with UTI were included in the study. The occurrence rates of isolated pathogens were as follows: Enterococcus spp., 35.15%; Escherichia coli, 22.32%; Staphylococcus aureus spp., 7.73%; Streptococcus spp., 7.51%; and Klebsiella spp., 6.95%. Uropathogens had a low susceptibility to linezolid (3.47%), vancomycin (0.92%), imipenem (5.74%), and amikacin (3.17%), but they had a high susceptibility to erythromycin (90.52%), penicillin G (74.01%), cefotaxime (71.41%), cefazolin (73.41%), cefuroxime (72.52%), and aztreonam (70.11%). There is high antibiotic resistance in hospitalized children with UTI. Susceptibility testing should be carried out on all clinical isolates, and the empirical antibiotic treatment should be altered accordingly. © 2018 Japan Pediatric Society.

Genetic and biochemical characterization of an acquired subgroup B3 metallo-β-lactamase gene, blaAIM-1, and its unique genetic context in Pseudomonas aeruginosa from Australia.

PubMed

Yong, Dongeun; Toleman, Mark A; Bell, Jan; Ritchie, Brett; Pratt, Rachael; Ryley, Henry; Walsh, Timothy R

2012-12-01

Three clinical Pseudomonas aeruginosa isolates (WCH2677, WCH2813, and WCH2837) isolated from the Women's and Children's Hospital, Adelaide, Australia, produced a metallo-β-lactamase (MBL)-positive Etest result. All isolates were PCR negative for known MBL genes. A gene bank was created, and an MBL gene, designated bla(AIM-1), was cloned and fully characterized. The encoded enzyme, AIM-1, is a group B3 MBL that has the highest level of identity to THIN-B and L1. It is chromosomal and flanked by two copies (one intact and one truncated) of an ISCR element, ISCR15. Southern hybridization studies indicated the movement of both ISCR15 and bla(AIM-1) within the three different clinical isolates. AIM-1 hydrolyzes most β-lactams, with the exception of aztreonam and, to a lesser extent, ceftazidime; however, it possesses significantly higher k(cat) values for cefepime and carbapenems than most other MBLs. AIM-1 was the first mobile group B3 enzyme detected and signals further problems for already beleaguered antimicrobial regimes to treat serious P. aeruginosa and other Gram-negative infections.

Nosocomial bacteremia and urinary tract infections caused by extended-spectrum beta -lactamase-producing Klebsiella pneumoniae with plasmids carrying both SHV-5 and TLA-1 genes.

PubMed

Alcantar-Curiel, Dolores; Tinoco, Juan Carlos; Gayosso, Catalina; Carlos, Angeles; Daza, Carlos; Perez-Prado, Maria C; Salcido, Lorena; Santos, Jose I; Alpuche-Aranda, Celia M

2004-04-15

We describe the prevalence and molecular characteristics of extended-spectrum beta -lactamase (ESBL)-producing Klebsiella pneumoniae causing nosocomial bacteremia and urinary tract infections in a Mexican general hospital. We analyzed 82 episodes of bacteremia (approximately 60% of episodes) and urinary tract infection (approximately 40% of episodes) due to K. pneumoniae during a 23-month surveillance period. The neonatal intensive care unit accounted for 49% of all episodes. All strains were imipenem susceptible; 62.2% of the strains were resistant to ceftazidime, cefotaxime, and aztreonam; 69.5% were resistant to amikacin; 58.5% were resistant to gentamicin; and 7.3% were resistant to ciprofloxacin. All strains were associated with 28 pulsed-field gel electrophoresis patterns, and dissemination of 2 ceftazidime-resistant clones produced 44% of the cases. The ESBL phenotype in these clones was transferred by identical or highly related megaplasmids. The ESBL activity corresponded to SHV-5 and TLA-1. Cross-transmission of 2 ceftazidime-resistant clones and the horizontal spread of identical or highly related megaplasmids explain the high prevalence of ESBL phenotype in these infections.

[Antibiotics sensitivity and characteristics of the esculin-positive Pseudomonas aeruginosa biovar].

PubMed

Sivolodskiĭ, E P

2000-01-01

Strains of Pseudomonas aeruginosa hydrolyzing esculin were isolated for the first time. They amount to 17.1 +/- 2.0% (60 from 325) of the investigated P. aeruginosa strains isolated from the clinical material in St. Petersburg. Esculin hydrolysis was measured by micromethod in plates, results were analysed after 3-hours incubation at 37 degrees C. Esculin-positive strains possesed biovar properties: they are widely spread, demonstrated other characteristic features (absence of triethylamine odour, specific colonies lysis), are stable on ability to hydrolyse esculin while culture storage and after repeated culturing. Typical strain of esculinolytica biovar was deposited into the culture collection of the National Research Institute of Agricultural Microbiology as P. aeruginosa ARRIAM 64-A. Susceptibility testing of the esculin-positive strains by disk-diffusion method revealed that most strains were inhibited by imipenem (86.6%), amikacin (75.0%), ceftazidime (65.0%), meropenem (60.0%), aztreonam (51.6%). The percent of strains susceptible to other antibiotics was lower: azlocillin--33.3%, netilmycin--33.3%, piperacillin--26.6%, ceftriaxon--18.3%. Only small number of strains were inhibited by ciprofloxacin (8.3%), gentamycin (3.4%), cefoperazone (1.7%) and carbenicillin (1.7%). The results may be used for empiric therapy before the isolated strain susceptibility is tested but only according to positive esculin-hydrolysis express-test evaluated in 3-hours period.

Clinical cure and survival in Gram-positive ventilator-associated pneumonia: retrospective analysis of two double-blind studies comparing linezolid with vancomycin.

PubMed

Kollef, Marin H; Rello, Jordi; Cammarata, Sue K; Croos-Dabrera, Rodney V; Wunderink, Richard G

2004-03-01

To assess the effect of baseline variables, including treatment, on clinical cure and survival rates in patients with Gram-positive, ventilator-associated pneumonia (VAP). Retrospective analysis of two randomized, double-blind studies. Multinational study with 134 sites. 544 patients with suspected Gram-positive VAP, including 264 with documented Gram-positive VAP and 91 with methicillin-resistant S. aureus (MRSA) VAP. Linezolid 600 mg or vancomycin 1 g every 12 h for 7-21 days, each with aztreonam. Clinical cure rates assessed 12-28 days after the end of therapy and excluding indeterminate or missing outcomes significantly favored linezolid in the Gram-positive and MRSA subsets. Logistic regression showed that linezolid was an independent predictor of clinical cure with odds ratios of 1.8 for all patients, 2.4 for Gram-positive VAP, and 20.0 for MRSA VAP. Kaplan-Meier survival rates favored linezolid in the MRSA subset. Logistic regression showed that linezolid was an independent predictor of survival with odds ratios of 1.6 for all patients, 2.6 for Gram-positive VAP, and 4.6 for MRSA VAP. Initial linezolid therapy was associated with significantly better clinical cure and survival rates than was initial vancomycin therapy in patients with MRSA VAP.

Phylogenetic groups among Klebsiella pneumoniae isolates from Brazil: relationship with antimicrobial resistance and origin.

PubMed

de Melo, Maíra Espíndola Silva; Cabral, Adriane Borges; Maciel, Maria Amélia Vieira; da Silveira, Vera Magalhães; de Souza Lopes, Ana Catarina

2011-05-01

The objectives of this study were to determine the distribution of phylogenetic groups among Klebsiella pneumoniae isolates from Recife, Brazil and to assess the relationship between the groups and the isolation sites and resistance profile. Ninety four isolates of K. pneumoniae from hospital or community infections and from normal microbiota were analyzed by gyrA PCR-RFLP, antibiotic susceptibility, and adonitol fermentation. The results revealed the distinction of three phylogenetic groups, as it has also been reported in Europe, showing that these clusters are highly conserved within K. pneumoniae. Group KpI was dominantly represented by hospital and community isolates while groups KpII and KpIII displayed mainly normal microbiota isolates. The resistance to third generation cephalosporins, aztreonam, imipenem, amoxicillin/clavulanic acid, and streptomycin was only observed in KpI. The percentage of resistance was higher in KpI, followed by KpII and KpIII. The differences in the distribution of K. pneumoniae phylogenetic groups observed in this study suggest distinctive clinical and epidemiological characteristics among the three groups, which is important to understand the epidemiology of infections caused by this organism. This is the first study in Brazil on K. pneumoniae isolates from normal microbiota and community infections regarding the distribution of phylogenetic groups based on the gyrA gene.

Diversity of Antimicrobial Resistance and Virulence Determinants in Pseudomonas aeruginosa Associated with Fresh Vegetables

PubMed Central

Allydice-Francis, Kashina; Brown, Paul D.

2012-01-01

With the increased focus on healthy eating and consuming raw vegetables, this study assessed the extent of contamination of fresh vegetables by Pseudomonas aeruginosa in Jamaica and examined the antibiotic susceptibility profiles and the presence of various virulence associated determinants of P. aeruginosa. Analyses indicated that vegetables from retail markets and supermarkets were widely contaminated by P. aeruginosa; produce from markets were more frequently contaminated, but the difference was not significant. Lettuce and carrots were the most frequently contaminated vegetables, while tomatoes were the least. Pigment production (Pyoverdine, pyocyanin, pyomelanin and pyorubin), fluorescein and alginate were common in these isolates. Imipenem, gentamicin and ciprofloxacin were the most inhibitory antimicrobial agents. However, isolates were resistant or showed reduced susceptibility to ampicillin, chloramphenicol, sulphamethoxazole/trimethoprim and aztreonam, and up to 35% of the isolates were resistant to four antimicrobial agents. As many as 30% of the isolates were positive for the fpv1 gene, and 13% had multiple genes. Sixty-four percent of the isolates harboured an exoenzyme gene (exoS, exoT, exoU or exoY), and multiple exo genes were common. We conclude that P. aeruginosa is a major contaminant of fresh vegetables, which might be a source of infection for susceptible persons within the community. PMID:23213336

Chryseobacterium meningosepticum infections in a dialysis unit.

PubMed

Perera, Shalinie; Palasuntheram, C

2004-06-01

Chryseobacterium species are Gram-negative bacteria with an unusual antibiotic profile. Chryseobacterium meningosepticum is the species most commonly encountered as a human pathogen. To study the microbiological, clinical and therapeutic features of C. meningosepticum infections in patients on dialysis, at Sri Jayewardenepura General Hospital (Teaching) (SJGH), and to trace the source of infections. A retrospective descriptive study. Dialysis unit of SJGH. population Patients who underwent long term haemodialysis (HD) and manual intermittent peritoneal dialysis (IPD) in the dialysis unit. Clinical and microbiological records of patients with C. meningosepticum infections over a period of 2 years were reviewed retrospectively. Environmental screening was carried out to detect a possible source of infection. Thirty five episodes of infection due to C. meningosepticum in 33 patients on HD and IPD were detected. There were 30 episodes of peritonitis, four of bacteraemia and one of asymptomatic colonization of a PD catheter. Isolates were resistant to aminoglycosides, chephalosporins and aztreonam, and sensitive to cotrimoxazole, vancomycin and rifampicin. They showed variable sensitivity to imipenem and ciprofloxacin. All except one patient had a favourable outcome. C. meningosepticum was cultured from a sink in the dialysis unit, but the original source of the organism was not known. C. meningosepticum could be an important pathogen in a dialysis unit, and fluoroquinolones and vancomycin are effective as empiric therapy.

[The combination effects of antibacterial agents against clinical isolated multiple-drug resistant Pseudomonas aeruginosa].

PubMed

Maesaki, Shigefumi; Yamaguchi, Toshiyuki; Sasaki, Kazumasa; Hashikita, Giichi; Shibuya, Shunsuke; Watanabe, Masaharu; Takayama, Sadao; Kawakami, Sayoko; Nagasawa, Mitsuaki; Suzuki, Noriyasu; Uchida, Takashi; Okabe, Tadashi; Kobayashi, Sugako

2006-02-01

The effectiveness of antibacterial agents against 70 strains of clinically isolated multiple-drug resistant Pseudomonas aeruginosa (MDRP) was measured by the micro dilution method. Fifty of all strains (71%) produced metallo-beta-lactamase and the IMP-1 gene was detected by polymerase chain reaction (PCR). The MIC90 (the minimum inhibitory concentration of an antibiotic necessary to inhibit the growth of 90% of bacterial strains) values of biapenem (BIPM), meropenem (MEPM), tazobactam/piperacillin (TAZ/PIPC), sulbactam/ cefoperazone (SBT/CPZ), cefepime (CFPM), ciprofloxacin (CPFX), pazufloxacin (PZFX), amikacin (AMK) and aztreonam (AZT) were found to be 265, 512, 256, 512, 512, 64, 128, 128 and 128 microg/mL, respectively. The in vitro combination effects of antibacterial agents were examined against 62 strains of MDRP and the synergy or additive effects were evaluated by fractional inhibitory concentration (FIC) index calculated by the checkerboard method. The combination of AMK and AZT showed synergy effects on 15/59 (25.4%) strains of MDRP. The synergy and additive effects on the MDRP strains were also found by the other antibacterial agents combination such as TAZ/PIPC and AMK, CFPM and AMK, and SBT/CPZ and AZT. These results suggested the necessity of further investigation of clinical usefulness.

Substrate Specificities of MexAB-OprM, MexCD-OprJ, and MexXY-OprM Efflux Pumps in Pseudomonas aeruginosa

PubMed Central

Masuda, Nobuhisa; Sakagawa, Eiko; Ohya, Satoshi; Gotoh, Naomasa; Tsujimoto, Hideto; Nishino, Takeshi

2000-01-01

To find the exact substrate specificities of three species of tripartite efflux systems of Pseudomonas aeruginosa, MexAB-OprM, MexCD-OprJ, and MexXY-OprM, we constructed a series of isogenic mutants, each of which constitutively overproduced one of the three efflux systems and lacked the other two, and their isogenic mutants, which lacked all these systems. Comparison of the susceptibilities of the constructed mutants to 52 antimicrobial agents belonging to various groups suggested the following substrate specificities. All of the efflux systems extrude a wide variety of antimicrobial agent groups, i.e., quinolones, macrolides, tetracyclines, lincomycin, chloramphenicol, most penicillins (all but carbenicillin and sulbenicillin), most cephems (all but cefsulodin and ceftazidime), meropenem, and S-4661, but none of them extrude polymyxin B or imipenem. Extrusion of aminoglycosides is specific to MexXY-OprM, and extrusion of a group of the β-lactams, i.e., carbenicillin, sulbenicillin, ceftazidime, moxalactam, and aztreonam, is specific to MexAB-OprM. Moreover, MexAB-OprM and MexCD-OprJ extrude novobiocin, cefsulodin, and flomoxef, while MexXY-OprM does not. These substrate specificities are distinct from those reported previously. PMID:11083635

Beta-lactam hypersensitivity and cross-reactivity.

PubMed

Terico, Adrienne T; Gallagher, Jason C

2014-12-01

Penicillin is the most frequently reported cause of drug allergy, and cross-reactivity of penicillins with other beta-lactam antibiotics is an area of debate. This review evaluates the available data on immunoglobulin E-mediated penicillin hypersensitivity and cross-reactivity with cephalosporin, carbapenem, and monobactam antibiotics. A MEDLINE search was conducted from 1950 to October 2013, and selected references from review articles were also evaluated. There is a wide variety in reported incidences of cross-reactivity between penicillins and cephalosporins or carbapenems, with early retrospective studies suggesting up to 41.7% and 47.4% cross-reactivity, respectively. Conversely, the use of monobactam antibiotics is frequently employed in the case of a penicillin allergy, as prescribers believe that there is no cross-reactivity between the 2 drug classes. More recent prospective studies suggest that the rates of cross-reactivity with cephalosporins and carbapenems are <5% and <1%, respectively. Similarities in penicillin and cephalosporin side chains may play a role in cross-reactivity between these classes. Cross-reactivity with monobactams is essentially negligible; however, there are some clinical data to support an interaction between ceftazidime and aztreonam, due to the similarity of their side chains. The data reviewed suggest that avoidance of other beta-lactams in patients with type 1 hypersensitivity to penicillins should be reconsidered. © The Author(s) 2014.

SHV-7, a novel cefotaxime-hydrolyzing beta-lactamase, identified in Escherichia coli isolates from hospitalized nursing home patients.

PubMed Central

Bradford, P A; Urban, C; Jaiswal, A; Mariano, N; Rasmussen, B A; Projan, S J; Rahal, J J; Bush, K

1995-01-01

Four ceftazidime-resistant Escherichia coli strains were isolated from elderly nursing home patients in a New York hospital during 1993. Strains MCQ-2, MCQ-3, and MCQ-4 were determined to be identical by pulsed-field gel electrophoresis and plasmid profiles, whereas strain MCQ-1 was unique. Strain MCQ-1 was determined to produce a TEM-10 beta-lactamase. Strains MCQ-2, MCQ-3, and MCQ-4 were also noted to be resistant to cefotaxime. These three strains produced two beta-lactamases with pIs of 5.4 (TEM-1) and 7.6. beta-Lactamase assays revealed that the pI 7.6 enzyme hydrolyzed cefotaxime faster (at a relative hydrolysis rate of 30% compared with that of benzylpenicillin) than either ceftazidime or aztreonam (relative hydrolysis rates of 13 and 3.3%, respectively). Nucleotide sequencing of the gene encoding the pI 7.6 beta-lactamase from strain MCQ-3 revealed a blaSHV-type gene differing from the gene encoding SHV-1 at four nucleotides which resulted in amino acid substitutions: phenylalanine for isoleucine at position 8, serine for arginine at position 43, serine for glycine at position 238, and lysine for glutamate at position 240. This novel SHV-type extended-spectrum beta-lactamase is designated SHV-7. PMID:7785992

A Simple Assay to Screen Antimicrobial Compounds Potentiating the Activity of Current Antibiotics

PubMed Central

Iqbal, Junaid; Kazmi, Shahana Urooj; Khan, Naveed Ahmed

2013-01-01

Antibiotic resistance continues to pose a significant problem in the management of bacterial infections, despite advances in antimicrobial chemotherapy and supportive care. Here, we suggest a simple, inexpensive, and easy-to-perform assay to screen antimicrobial compounds from natural products or synthetic chemical libraries for their potential to work in tandem with the available antibiotics against multiple drug-resistant bacteria. The aqueous extract of Juglans regia tree bark was tested against representative multiple drug-resistant bacteria in the aforementioned assay to determine whether it potentiates the activity of selected antibiotics. The aqueous extract of J. regia bark was added to Mueller-Hinton agar, followed by a lawn of multiple drug-resistant bacteria, Salmonella typhi or enteropathogenic E. coli. Next, filter paper discs impregnated with different classes of antibiotics were placed on the agar surface. Bacteria incubated with extract or antibiotics alone were used as controls. The results showed a significant increase (>30%) in the zone of inhibition around the aztreonam, cefuroxime, and ampicillin discs compared with bacteria incubated with the antibiotics/extract alone. In conclusion, our assay is able to detect either synergistic or additive action of J. regia extract against multiple drug-resistant bacteria when tested with a range of antibiotics. PMID:23865073

Recovery method development of sodium chloride-susceptible methicillin-resistant Staphylococcus aureus isolates from ground pork samples.

PubMed

Pang, Lu; Luo, Yanping; Gu, Yihai; Xu, Xiao; Xu, Jin; Zhang, Fenglan; Cui, Shenghui

2015-02-01

The growth of certain methicillin-resistant Staphylococcus aureus (MRSA) isolates could be inhibited by NaCl higher than 2.5%. The objective of this study was to develop an enrichment method to recover NaCl-susceptible MRSA isolates from meat samples. The growth of 12 MRSA and 10 non-MRSA strains was measured in Mueller-Hinton (MH) broth supplemented with 2.5%, 4%, 6.5%, and 7.5% NaCl. Selective agents, including aztreonam, polymyxin B, NaCl, nalidixic acid, and NaN3, were determined for their inhibitory effect to MRSA and non-MRSA strains in MH broth. Based on these data, a two-step enrichment method was developed to recover both NaCl-susceptible and -resistant MRSA isolates in meat products. Comparing to the enrichment method that only used MH broth supplemented with 6.5% NaCl, five additional NaCl-susceptible MRSA isolates were recovered from 92 retail ground pork samples by this newly developed two-step enrichment method. To the best of our knowledge, this is the first study that considers NaCl-susceptible MRSA recovery from ground pork samples. The application of this new enrichment method might expand the diversity of MRSA isolates recovered from various samples.

Phenotypic detection of Klebsiella pneumoniae carbapenemase among burns patients: first report from Iran.

PubMed

Rastegar Lari, Abdolaziz; Azimi, Leila; Rahbar, Mohammad; Fallah, Fatemeh; Alaghehbandan, Reza

2013-02-01

Resistance to antimicrobial agents such as carbapenems among enterobacteriacea has been increasing, especially in Klebsiella pneumonia that produces variety of enzymes including Klebsiella pneumoniae carbapenemase (KPC). This study is the first report of its kind investigating the resistance to carbapenems among burns patients in Iran. During a 6-month period, 28 hospitalized burn patients who required to be placed on broad spectrum antibiotics were studied. Isolated species identified by routine biochemical test. Susceptibility testing for these species was performed by recommended the CLSI guidelines method. The tested antibiotics included cefotaxime, cefepime, aztreonam, imipenem, amoxicillin+clavulonic acid, gentamicin, amikacin, tobramycin, tetracycline, and trimethoprim-sulfamethoxazole, and chloramphenicol. For determination of KPC in phenotypical forms, Modified Hodge Test was utilized as per CLSI recommendation. Thirty-five Klebsiella spp. were isolated from 28 hospitalized patients. Nineteen out of 35 Klebsiella isolates were resistant to imipenem and that all of them had positive KPC. Nine of imipenem resistant isolates were also resistant to all tested antibiotics. Mortality rate among patients with positive KPC was 33%. High rate of multi-drug resistant (MDR) strains in isolates with positive KPC is a major challenge in Iran and that it could cause an increase in both mortality and morbidity among burn patients. Thus, appropriate infection control measures and guidelines are needed to prevent such infections among burn patients. Copyright © 2012 Elsevier Ltd and ISBI. All rights reserved.

Identification of extended spectrum beta lactamases, AmpC and carbapenemase production among isolates of Escherichia coli in North Indian tertiary care centre

PubMed Central

Chaudhary, Uma; Agarwal, Shipra; Raghuraman, Kausalya

2018-01-01

Introduction: Identification of Extended spectrum beta lactamases (ESBL), AmpC production and carbapenemase production among isolates of Escherichia coli, helps clinician to rationalize the choice of antibiotics. However, there is a lack of simple and effective method for simultaneous identification of these beta lactamases. Aim: To determine the concurrent production of beta lactamases using twelve disc method on E. coli isolates. Materials and Methods: A total of 200 multidrug resistant E. coli were screened using twelve disc method. The isolates of ESBL were confirmed by ceftazidime/clavulanic acid and cefotaxime/clavulanic acid method. Metallo-beta-lactamases (MBL) were confirmed by imipenem EDTA combined disc method. Results: Among the 200 isolates, 42.5% were ESBL producers, 9% were MBL and 6.5% were Klebsiella pneumoniae carbapenemase (KPC) and AmpC each respectively. Coproduction was seen in 54 (27%). A significant difference in sensitivity was seen in cefuroxime, aztreonam, cefoxitin and ceftriaxone among inpatient and outpatients. Conclusion: The present study highlights burden of ESBL, AmpC, KPC and MBL along with their coproduction in a tertiary care hospital. In-house antibiotic policy, infection control and epidemiological surveys will help us in controlling these resistant bugs. We believe, the twelve disc method is a simple, inexpensive screening method for beta lactamase production. PMID:29682477

Pork Meat as a Potential Source of Salmonella enterica subsp. arizonae Infection in Humans

PubMed Central

Kritas, Spyridon; Govaris, Alexander; Burriel, Angeliki R.

2014-01-01

Salmonella enterica subsp. arizonae was isolated from 13 of 123 slaughtered pigs in central Greece. The samples cultured were feces, ileum tissue, mesenteric lymph nodes, and gallbladder swabs. A total of 74 isolates from 492 samples were identified as Salmonella spp. by use of standard laboratory culture media and two commercial micromethods and by use of a polyvalent slide agglutination test for the detection of O and H antigens. Among them were 19 (25.68%) suspected to be S. enterica subsp. arizonae according to analysis with standard laboratory culture media. Of those, 14 were identified as S. enterica subsp. arizonae by the API 20E (bioMérieux, France) and the Microgen GnA+B-ID (Microgen Bioproducts, Ltd., United Kingdom) identification systems. All the isolates were tested for resistance to 23 antimicrobials. Strains identified as S. enterica subsp. arizonae were resistant to 17 (70.8%) antibiotics. The highest proportions of resistance were observed for sulfamethoxazole-trimethoprim (71.4%), tetracycline (71.4%), ampicillin (64.3%), and amoxicillin (57.1%). Two isolates were resistant to aztreonam (7.1%) and tigecycline (7.1%), used only for the treatment of humans. Thus, pork meat may play a role in the transmission of antibiotic-resistant S. enterica subsp. arizonae to human consumers. This is the first report of S. enterica subsp. arizonae isolation from pigs. PMID:24335956

Travellers' diarrhoea.

PubMed

Ericsson, Charles D

2003-02-01

Risk of travellers' diarrhoea is about 7% in developed countries and 20-50% in the developing world. Options for prevention include education and chemoprophylaxis. Vaccination is a promising but incomplete option. Achieving behaviour modification of food and water choices among tourists is difficult. Bismuth subsalicylate (BSS)-containing compounds are about 62% effective in the prevention of travellers' diarrhoea. Antibiotics are about 84% effective in preventing travellers' diarrhoea. Routine prophylaxis of travellers' diarrhoea, especially with antibiotics, should be discouraged. Oral rehydration is generally important in the treatment of diarrhoea, but travellers' diarrhoea is only infrequently dehydrating in adults. The addition of oral rehydration solutions confers no additional benefit to loperamide in the treatment of travellers' diarrhoea in adults. Presently, the most active of the antibiotics routinely available for treatment are members of the fluoroquinolone group. Antibiotics that are not absorbed such as aztreonam and a rifampicin-like agent, rifaximin, are both effective. The latter might become a therapy of choice once it is routinely available, due to predictably less adverse reactions with a non-absorbed antibiotic. Preliminary results with azithromycin look very promising. Less severe disease can be treated with a variety of non-antibiotic agents (e.g. BSS-containing compounds, loperamide and a calmodulin inhibitor, zaldaride). The combination of an antibiotic and loperamide is superior to treatment with either agent alone in a several studies and is arguably the treatment of choice for distressing travellers' diarrhoea.

Diversity of fecal coliforms and their antimicrobial resistance patterns in wastewater treatment model plant.

PubMed

Luczkiewicz, A; Fudala-Ksiazek, S; Jankowska, K; Quant, B; Olańczuk-Neyman, K

2010-01-01

The occurrence of resistance patterns among wastewater fecal coliforms was determined in the study. Susceptibility of the isolates was tested against 19 antimicrobial agents: aminoglycosides, aztreonam, carbapenems, cephalosporines, beta-lactam/beta-lactamase inhibitors, penicillines, tetracycline, trimethoprim/sulfamethoxazole, and fluoroquinolones. Additionally the removal of resistant isolates was evaluated in the laboratory-scale wastewater treatment model plant (M-WWTP), continuously supplied with the wastewater obtained from the full-scale WWTP. Number of fecal coliforms in raw (after mechanical treatment) and treated wastewater, as well as in aerobic chamber effluent was determined using selective medium. The selected strains were identified and examined for antibiotic resistance using Phoenix Automated Microbiology System (BD Biosciences, USA). The strains were identified as Escherichia coli (n=222), Klebsiella pneumoniae ssp. ozaenae (n=9), and Pantoea agglomerans (n=1). The isolate of P. agglomerans as well as 48% of E. coli isolates were sensitive to all antimicrobials tested. The most frequent resistance patterns were found for ampicillin: 100% of K. pneumoniae ssp. ozaenae and 41% of E. coli isolates. Among E. coli isolates 12% was regarded as multiple antimicrobial resistant (MAR). In the studied M-WWTP, the applied activated sludge processes reduced considerably the number of fecal coliforms, but increased the ratio of antimicrobial-resistant E. coli isolates to sensitive ones, especially among strains with MAR patterns.

Pork meat as a potential source of Salmonella enterica subsp. arizonae infection in humans.

PubMed

Evangelopoulou, Grammato; Kritas, Spyridon; Govaris, Alexander; Burriel, Angeliki R

2014-03-01

Salmonella enterica subsp. arizonae was isolated from 13 of 123 slaughtered pigs in central Greece. The samples cultured were feces, ileum tissue, mesenteric lymph nodes, and gallbladder swabs. A total of 74 isolates from 492 samples were identified as Salmonella spp. by use of standard laboratory culture media and two commercial micromethods and by use of a polyvalent slide agglutination test for the detection of O and H antigens. Among them were 19 (25.68%) suspected to be S. enterica subsp. arizonae according to analysis with standard laboratory culture media. Of those, 14 were identified as S. enterica subsp. arizonae by the API 20E (bioMérieux, France) and the Microgen GnA+B-ID (Microgen Bioproducts, Ltd., United Kingdom) identification systems. All the isolates were tested for resistance to 23 antimicrobials. Strains identified as S. enterica subsp. arizonae were resistant to 17 (70.8%) antibiotics. The highest proportions of resistance were observed for sulfamethoxazole-trimethoprim (71.4%), tetracycline (71.4%), ampicillin (64.3%), and amoxicillin (57.1%). Two isolates were resistant to aztreonam (7.1%) and tigecycline (7.1%), used only for the treatment of humans. Thus, pork meat may play a role in the transmission of antibiotic-resistant S. enterica subsp. arizonae to human consumers. This is the first report of S. enterica subsp. arizonae isolation from pigs.

Detection of antibiotic resistance in probiotics of dietary supplements.

PubMed

Wong, Aloysius; Ngu, Davey Yueh Saint; Dan, Lydia Annabel; Ooi, Amanda; Lim, Renee Lay Hong

2015-09-14

Probiotics are live microorganisms that confer nutrition- and health-promoting benefits if consumed in adequate amounts. Concomitant with the demand for natural approaches to maintaining health is an increase in inclusion of probiotics in food and health products. Since probiotic bacteria act as reservoir for antibiotic resistant determinants, the transfer of these genes to pathogens sharing the same intestinal habitat is thus conceivable considering the fact that dietary supplements contain high amounts of often heterogeneous populations of probiotics. Such events can confer pathogens protection against commonly-used drugs. Despite numerous reports of antibiotic resistant probiotics in food and biological sources, the antibiogram of probiotics from dietary supplements remained elusive. Here, we screened five commercially available dietary supplements for resistance towards antibiotics of different classes. Probiotics of all batches of products were resistant towards vancomycin while batch-dependent resistance towards streptomycin, aztreonam, gentamycin and/or ciprofloxacin antibiotics was detected for probiotics of brands Bi and Bn, Bg, and L. Isolates of brand Cn was also resistant towards gentamycin, streptomycin and ciprofloxacin antibiotics. Additionally, we also report a discrepancy between the enumerated viable bacteria amounts and the claims of the manufacturers. This short report has highlighted the present of antibiotic resistance in probiotic bacteria from dietary supplements and therefore serves as a platform for further screenings and for in-depth characterization of the resistant determinants and the molecular machinery that confers the resistance.

[Multiresistant Pseudomonas spp. in vitro susceptibility to a combination of two antibiotics].

PubMed

Pliego-Castañeda, Q F B Amanda; Yánez-Viguri, Jorge Antonio; López-Valle, Tiburcio

2005-01-01

In vitro antibiotic combination testing would guide therapy selection in patients severely affected by multi-drug resistant Pseudomonas. In vitro, a two-antibiotic combination susceptible against multi-drug resistant Pseudomonas isolated at the Laboratorio Clínico of the Hospital de Oncología, Centro Médico Nacional Siglo XXI in Mexico City were analyzed to determine which antibiotic combination showed the best bactericidal activity. During 10 months, 30 multi-drug resistant Pseudomonas strains were tested. An automated method was used, including a diluting solution with a well-known concentration of a second antibiotic. Quality controls recommended by the NCCLS were used. Pseudomonas aeruginosa ATCC 27853; Escherichia coli ATCC 25922; and Escherichia coli ATCC 35218. Combinations were betalactamics-aminoglycosides; carbapenemis-amikacin; fluoroquinolones-cefepime; and ciprofloxacin-ampicillin. Ampicillin-ciprofloxacin combination was bactericidal against 100% of the isolates. Cefazolin, cefixime and ticarcillin with amikacin: <50%; aztreonam, cefoxilin, cefuroxime, cefotaxime, ceftazidime and piperacillin with amikacin: 50-60%; cefepime with gentamicin: 76%; cefepime with amikacin: 86%; imipenem and meropenem with amikacin: 70% and 76%; cefepime with ciprofloxacin: 83%; cefepime with levofloxacin: 73%. In vitro antibiotic combination susceptibilities against multi-drug resistant bacteria would be the only way to guide clinicians to select the best therapy in severe infections. We found that the ampicillin-ciprofloxacin combination showed the best in vitro effect against multi-drug resistant Pseudomonas.

[Analysis of drug resistance of Acinetobacter baumannii in wound of children with traffic injury and its relationship with antibiotic use].

PubMed

Liu, S; Wang, C; Fu, Y X

2017-07-20

Objective: To know the drug resistance of Acinetobacter baumannii (AB) in wound of children with traffic injury and its relationship with antibiotic use. Methods: Wound exudate of 226 children with traffic injury admitted to our unit from January 2010 to December 2015 were collected. API bacteria identification panels and fully automatic microbiological identification system were used to identify pathogens. Kirby-Bauer paper disk diffusion method was used to detect the drug resistance of pathogens to 18 antibiotics including amoxycillin/clavulanic acid, piperacillin/tazobactam, and imipenem. The detection situation of pathogen of children's wounds and drug resistance of detected AB to 18 antibiotics in each year were collected. Forty-six AB positive children (2 children excluded) were divided into imipenem-resistant group (IR, n =19) and non imipenem-resistant group (NIR, n =25) according to whether AB was 100% resistant to imipenem. Drug resistance of AB in wounds of children to 18 antibiotics in two groups was compared. The antibiotic use of AB positive children was collected, and the antibiotic use intensity of children in two groups was compared. Data were processed with Fisher's exact test, independent sample t test, and corrected t test. Results: (1) The detection rates of pathogen in wounds of children in 2010-2015 were 95.6% (43/45), 89.8% (53/59), 81.3% (148/182), 81.1% (107/132), 81.6% (120/147), and 77.5% (62/80), respectively, showing a trend of decreasing year by year. A total of 665 strains and 75 pathogens were detected, and the top 5 pathogens with detection rate from high to low were AB, Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus epidermidis, and Escherichia coli, respectively. (2) Drug resistance rates of AB to amoxycillin/clavulanic acid, cefazolin, aztreonam, and piperacillin were all 100%, while AB was 100% sensitive to polymyxin, and the total drug resistance rates of AB to the other 13 antibiotics were all above 50%. The drug resistance rate of AB in wounds of children to piperacillin was higher than that to piperacillin/tazobactam in 2010-2015. (3) Except for imipenem, amoxycillin/clavulanic acid, cefazolin, aztreonam, piperacillin, and polymyxin, the drug resistance rates of AB in wounds of children in group IR to the other 12 antibiotics were higher than those in group NIR (with P values below 0.01). Besides, AB strains in wounds of children in group IR were completely resistant to at least 3 kinds of antibiotics including carbapenems, aminoglycosides, and quinolones, so that they were multidrug-resistant AB. (4) A total of 32 antibiotics were used in 46 AB positive children, and the 10-top-used antibiotics with use intensity from high to low were cefoperazone/sulbactam, piperacillin/tazobactam, cefazolin, imipenem, ceftizoxime, amoxycillin/clavulanate, ceftazidime, cefepime, amoxycillin/sulbactam, and cefmetazole, respectively. (5) Twenty-one antibiotics were not included in the comparison because of their small amount of usage. For the other 11 antibiotics, only the use intensity of metronidazole of children in two groups was statistically different ( t =-3.104, P <0.05). There was no statistically significant difference in total antibiotic use of children in two groups ( t =0.368, P >0.05). Conclusions: AB is one of the main pathogens in wounds of children with traffic injury, with high drug resistant rate. The high intensity of antibiotic use may lead to its drug resistance. In this study, the top-used antibiotics were in accord with AB resistant drugs, indicating a lack of normative use of antibiotics.

Continuous-Infusion Antipseudomonal Beta-Lactam Therapy in Patients With Cystic Fibrosis

PubMed Central

Prescott, William A.; Gentile, Allison E.; Nagel, Jerod L.; Pettit, Rebecca S.

2011-01-01

Objective: We sought to evaluate the pharmacokinetics, efficacy, safety, stability, pharmacoeconomics, and quality-of-life effects of continuous-infusion antipseudomonal beta-lactam therapy in patients with cystic fibrosis (CF). Data Sources: Literature retrieval was accessed through Medline (from 1950 to December 2010) using the following terms: cystic fibrosis; beta-lactams or piperacillin or ticarcillin or cefepime or ceftazidime or doripenem or meropenem or imipenem/cilastin or aztreonam; continuous infusion or constant infusion; drug stability; economics, pharmaceutical; and quality of life. In addition, reference citations from identified publications were reviewed. Study Selection and Data Extraction: We evaluated all articles in English identified from the data sources. Data Synthesis: Patients with CF often harbor colonies of multidrug-resistant organisms, increasing the risk of suboptimal dosing and failure to meet the time above the minimum inhibitory concentration (T > MIC) pharmacodynamic targets. The pharmacokinetics of continuous-infusion antipseudomonal beta-lactam therapy in CF maintains serum concentrations above the MIC of susceptible strains and is more likely than intermittent infusion to achieve optimal T > MIC targets for some intermediate and resistant strains of Pseudomonas aeruginosa. Three noncomparative and four comparative studies have assessed the efficacy and safety of continuous-infusion antipseudomonal beta-lactam therapy during CF pulmonary exacerbations. Ceftazidime, the most extensively studied antibiotic for continuous infusion in CF, has been shown to improve forced expiratory volume in 1 second (FEV1), to improve forced vital capacity (FVC), and to extend the time between pulmonary exacerbations. Continuous-infusion cefepime has been studied in a small number of patients, and a trend toward improved pulmonary function has been observed. Continuous-infusion antipseudomonal beta-lactam therapy appears to be well tolerated, although most of the data pertain to ceftazidime. Because continuous infusion may necessitate that patients wear a portable pump in close proximity to the body, the stability of the antibiotic at body temperature must be considered. Several beta-lactams have good stability at body temperature (piperacillin/tazobactam, ticarcillin/clavulanate, and aztreonam) or acceptable if the medication cartridge is changed twice daily (cefepime and doripenem), whereas other beta-lactams have acceptable 24-hour stability only at lower temperatures (cefepime, ceftazidime, doripenem, and meropenem). Although no pharmacoeconomic studies have evaluated the cost–benefit of continuous infusion versus intermittent infusion in patients with CF, the potential medication cost reduction appears to be considerable. There is little information regarding the impact of continuous infusion on quality of life in patients with CF. Conclusion: Efficacy and safety studies suggest that ceftazidime, administered as a continuous infusion for the treatment of CF pulmonary exacerbations, is safe and effective; has the potential to reduce the costs of treatment; and is preferred to intermittent infusion among patients treated at home. Continuous-infusion ceftazidime may therefore be an alternative to traditional dosing on a case-by-case basis, such as for patients with multidrug-resistant isolates of P. aeruginosa. Treatment with continuous-infusion ceftazidime at home may be considered in such a case, assuming resources and support equivalent to the hospital setting can be ensured. Additional studies assessing the safety and efficacy of other antipseudomonal beta-lactams, when administered as a continuous infusion, during CF pulmonary exacerbations are needed. PMID:22346306

Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Enterobacteriaceae with Vitek 2 (2009 FDA) and 2014 CLSI Breakpoints

PubMed Central

Bobenchik, April M.; Deak, Eszter; Hindler, Janet A.; Charlton, Carmen L.

2014-01-01

Vitek 2 (bioMérieux Inc., Durham, NC) is a widely used commercial antimicrobial susceptibility test system. We compared the MIC results obtained using the Vitek 2 AST-GN69 and AST-XN06 cards to those obtained by CLSI broth microdilution (BMD) for 255 isolates of Enterobacteriaceae, including 25 isolates of carbapenem-resistant Enterobacteriaceae. In total, 25 antimicrobial agents were examined. For 10 agents, the MIC data were evaluated using two sets of breakpoints: (i) the Vitek 2 breakpoints, which utilized the 2009 FDA breakpoints at the time of the study and are equivalent to the 2009 CLSI M100-S19 breakpoints, and (ii) the 2014 CLSI M100-S24 breakpoints. There was an overall 98.7% essential agreement (EA). The categorical agreement was 95.5% (CA) using the Vitek 2 breakpoints and 95.7% using the CLSI breakpoints. There was 1 very major error (VME) (0.05%) observed using the Vitek 2 breakpoints (cefazolin) and 8 VMEs (0.5%) using the CLSI breakpoints (2 each for aztreonam, cefepime, and ceftriaxone, and 1 for cefazolin and ceftazidime). Fifteen major errors (MEs) (0.4%) were noted using the Vitek 2 breakpoints and 8 (0.5%) using the CLSI breakpoints. Overall, the Vitek 2 performance was comparable to that of BMD for testing a limited number of Enterobacteriaceae commonly isolated by clinical laboratories. Ongoing studies are warranted to assess performance in isolates with emerging resistance. PMID:25540403

Chitin Oligosaccharide (COS) Reduces Antibiotics Dose and Prevents Antibiotics-Caused Side Effects in Adolescent Idiopathic Scoliosis (AIS) Patients with Spinal Fusion Surgery.

PubMed

Qu, Yang; Xu, Jinyu; Zhou, Haohan; Dong, Rongpeng; Kang, Mingyang; Zhao, Jianwu

2017-03-14

Antibiotics are always considered for surgical site infection (SSI) in adolescent idiopathic scoliosis (AIS) surgery. However, the use of antibiotics often causes the antibiotic resistance of pathogens and side effects. Thus, it is necessary to explore natural products as drug candidates. Chitin Oligosaccharide (COS) has anti-inflammation and anti-bacteria functions. The effects of COS on surgical infection in AIS surgery were investigated. A total of 312 AIS patients were evenly and randomly assigned into control group (CG, each patient took one-gram alternative Azithromycin/Erythromycin/Cloxacillin/Aztreonam/Ceftazidime or combined daily), experiment group (EG, each patient took 20 mg COS and half-dose antibiotics daily), and placebo group (PG, each patient took 20 mg placebo and half-dose antibiotics daily). The average follow-up was one month, and infection severity and side effects were analyzed. The effects of COS on isolated pathogens were analyzed. SSI rates were 2%, 3% and 8% for spine wounds and 1%, 2% and 7% for iliac wound in CG, EG and PG ( p < 0.05), respectively. COS reduces the side effects caused by antibiotics ( p < 0.05). COS improved biochemical indexes and reduced the levels of interleukin (IL)-6 and tumor necrosis factor (TNF) alpha. COS reduced the antibiotics dose and antibiotics-caused side effects in AIS patients with spinal fusion surgery by improving antioxidant and anti-inflammatory activities. COS should be developed as potential adjuvant for antibiotics therapies.

Risk factors of all-cause in-hospital mortality among Korean elderly bacteremic urinary tract infection (UTI) patients.

PubMed

Chin, Bum Sik; Kim, Myung Soo; Han, Sang Hoon; Shin, So Youn; Choi, Hee Kyung; Chae, Yun Tae; Jin, Sung Joon; Baek, Ji-Hyeon; Choi, Jun Yong; Song, Young Goo; Kim, Chang Oh; Kim, June Myung

2011-01-01

Urinary tract infection (UTI) is the most frequent cause of bacteremia/sepsis in elderly people and increasing antimicrobial resistance in uropathogens has been observed. To describe the characteristics of bacteremic UTI in elderly patients and to identify the independent risk factors of all-cause in-hospital mortality, a retrospective cohort study of bacteremic UTI patients of age over 65 was performed at a single 2000-bed tertiary hospital. Bacteremic UTI was defined as the isolation of the same organism from both urine and blood within 48 h. Eighty-six elderly bacteremic UTI patients were enrolled. Community-acquired infection was the case for most patients (79.1%), and Escherichia coli accounted for 88.6% (70/79) among Gram-negative organisms. Non-E. coli Gram-negative organisms were more frequent in hospital-acquired cases and male patients while chronic urinary catheter insertion was related with Gram-positive urosepsis. The antibiotic susceptibility among Gram-negative organisms was not different depending on the source of bacteremic UTI, while non-E. coli Gram-negative organisms were less frequently susceptible for cefotaxime, cefoperazone/sulbactam, and aztreonam. All-cause in-hospital mortality was 11.6%, and functional dependency (adjusted hazard ratio=HR=10.9, 95% confidence interval=95%CI=2.2-54.6) and low serum albumin (adjusted HR=27.0, 95%CI=2.0-361.2) were independently related with increased all-cause in-hospital mortality. Crown Copyright © 2010. Published by Elsevier Ireland Ltd. All rights reserved.

In-silico modeling of a novel OXA-51 from β-lactam-resistant Acinetobacter baumannii and its interaction with various antibiotics.

PubMed

Tiwari, Vishvanath; Nagpal, Isha; Subbarao, Naidu; Moganty, Rajeswari R

2012-07-01

Acinetobacter baumannii, one of the major Gram negative bacteria, causes nosocomial infections such as pneumonia, urinary tract infection, meningitis, etc. β-lactam-based antibiotics like penicillin are used conventionally to treat infections of A. baumannii; however, they are becoming progressively less effective as the bacterium produces diverse types of β-lactamases to inactivate the antibiotics. We have recently identified a novel β-lactamase, OXA-51 from clinical strains of A. baumannii from our hospital. In the present study, we generated the structure of OXA-51 using MODELLER9v7 and studied the interaction of OXA-51 with a number of β-lactams (penicillin, oxacillin, ceftazidime, aztreonam and imipenem) using two independent programs: GLIDE and GOLD. Based on the results of different binding parameters and number of hydrogen bonds, interaction of OXA-51 was found to be maximum with ceftazidime and lowest with imipenem. Further, molecular dynamics simulation results also support this fact. The lowest binding affinity of imipenem to OXA-51 indicates clearly that it is not efficiently cleaved by OXA-51, thus explaining its high potency against resistant A. baumannii. This finding is supported by experimental results from minimum inhibitory concentration analysis and transmission electron microscopy. It can be concluded that carbapenems (imipenem) are presently effective β-lactam antibiotics against resistant strains of A. baumannii harbouring OXA-51. The results presented here could be useful in designing more effective derivatives of carbapenem.

Stenotrophomonas maltophilia in Mexico: antimicrobial resistance, biofilm formation and clonal diversity.

PubMed

Flores-Treviño, Samantha; Gutiérrez-Ferman, Jessica Lizzeth; Morfín-Otero, Rayo; Rodríguez-Noriega, Eduardo; Estrada-Rivadeneyra, Diego; Rivas-Morales, Catalina; Llaca-Díaz, Jorge M; Camacho-Ortíz, Adrián; Mendoza-Olazarán, Soraya; Garza-González, Elvira

2014-11-01

Stenotrophomonas maltophilia is an important multidrug-resistant nosocomial pathogen associated with high mortality. Our aim was to examine antimicrobial susceptibility, biofilm production and clonal relatedness of clinical isolates of S. maltophilia. S. maltophilia isolates were collected between 2006 and 2013 from two tertiary care hospitals in Mexico. Antimicrobial susceptibility was evaluated by the broth microdilution method. PCR was used to determine the presence of β-lactamase genes L1 and L2. Biofilm formation was assessed with crystal violet staining. Clonal relatedness was determined by PFGE. Among the 119 collected S. maltophilia isolates, 73 (61.3%) were from the respiratory tract. Resistance levels exceeded 75% for imipenem, meropenem, ampicillin, aztreonam, gentamicin and tobramycin. Resistance to trimethoprim-sulfamethoxazole was 32.8%. L1 and L2 genes were detected in 77.1% (91/118) and 66.9% (79/118) of isolates, respectively. All S. maltophilia strains were able to produce biofilms. Strains were classified as weak (47.9%, 57/119), moderate (38.7%, 46/119), or strong (13.4%, 16/119) biofilm producers. A total of 89 distinct PFGE types were identified and 21.6% (22/102) of the isolates were distributed in nine clusters. This is the first study in Mexico to reveal characteristics of clinical isolates of S. maltophilia. Clonal diversity data indicate low cross-transmission of S. maltophilia in a hospital setting. The high antibiotic resistance underscores the need for continuous surveillance of S. maltophilia in hospital settings in Mexico. © 2014 The Authors.

Antibiotic resistance of lactic acid bacteria and Bifidobacterium spp. isolated from dairy and pharmaceutical products.

PubMed

D'Aimmo, Maria Rosaria; Modesto, Monica; Biavati, Bruno

2007-04-01

The outlines of antibiotic resistance of some probiotic microorganisms were studied. This study was conducted with the double purpose of verifying their ability to survive if they are taken simultaneously with an antibiotic therapy and to increase the selective properties of suitable media for the isolation of samples containing mixed bacterial populations. We isolated from commercial dairy and pharmaceutical products, 34 strains declared as probiotics, belonging to the genera Bifidobacterium and Lactobacillus, and 21 strains of starter culture bacteria. All the microorganisms have been compared by electrophoresis of the soluble proteins for the purpose of identifying them. A Multiplex-PCR with genus- and species-specific primers was used to detect for Bifidobacterium animalis subsp. lactis presence. All bifidobacteria were B. animalis subsp. lactis except one Bifidobacterium longum. Sometimes the identification showed that the used strain was not the one indicated on the label. The lactobacilli were Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus delbrueckii subsp. bulgaricus. The streptococci were all Streptococcus thermophilus. The minimal inhibitory concentration (MIC) of 24 common antibiotic substances has been valued by the broth microdilution method. All tested strains were susceptible to ampicillin, bacitracin, clindamycin, dicloxacillin, erytromycin, novobiocin, penicillin G, rifampicin (MIC(90) ranging from 0.01 to 4 microg/ml); resistant to aztreonam, cycloserin, kanamycin, nalidixic acid, polymyxin B and spectinomycin (MIC(90) ranging from 64 to >1000 microg/ml). The susceptibility to cephalothin, chloramphenicol, gentamicin, lincomycin, metronidazole, neomycin, paromomycin, streptomycin, tetracycline and vancomycin was variable and depending on the species.

Resistance Pattern and Detection of Metallo-beta-lactamase Genes in Clinical Isolates of Pseudomonas aeruginosa in a Central Nigeria Tertiary Hospital.

PubMed

Zubair, K O; Iregbu, K C

2018-02-01

Acquired metallo-β-lactamases (MBLs) pose serious problem both in terms of treatment and infection control in the hospitals and report across the world showed an increase in their prevalence. However, there is a paucity of data from Africa, and their report is rare in Nigeria. This study aimed to determine the prevalence of acquired MBL-resistant genes in carbapenem-resistant Pseudomonas aeruginosa in Abuja, North Central Nigeria. Two hundred nonduplicate, consecutive isolates of P. aeruginosa from clinical samples submitted to the Medical Microbiology Laboratory of National Hospital, Abuja were screened for carbapenem resistance using imipenem and meropenem. Phenotypic detection of MBL-producing strains was determined using Total MBL confirm kits and E-test strips on isolates that were resistant to both Imipenem and meropenem. The MBL genes were detected using multiplex polymerase chain reaction, while the gene variant was determined by sequencing. Twenty-two MBL-producing strains were detected phenotypically, but only 5 harbored the blaVIM-1 gene, giving a prevalence of 2.5%. These 5 strains were resistant to all the antipseudomonal antibiotics tested except Aztreonam and Colistin. Other common MBL-genes were not detected. The prevalence of MBL-producing strains of P. aeruginosa which poses serious challenge for therapeutics and infection control is currently low in Abuja, North Central, Nigeria. Therefore, rational use of the carbapenems and other antipseudomonal antibiotics, regular surveillance and adequate infection control measures should be instituted to limit further spread.

Desensitization to ceftaroline in a patient with multiple medication hypersensitivity reactions.

PubMed

Jones, Justin M; Richter, Lisa M; Alonto, Augusto; Leedahl, David D

2015-02-01

The case of a patient with multiple medication hypersensitivity reactions and a methicillin-resistant Staphylococcus aureus (MRSA) infection who underwent desensitization to ceftaroline is reported. A 32-year-old Caucasian woman with asthma, gastroesophageal reflux disease, heart murmur, and major depression was admitted for MRSA cellulitis with a subcutaneous abscess along the left sternomanubrial joint and clavicular osteomyelitis secondary to port placement after gastric bypass surgery. The patient had an extensive history of hypersensitivity reactions. Pertinent documented allergies were as follows: penicillin (anaphylaxis), daptomycin (anaphylaxis), vancomycin (hives), linezolid (hives), ertapenem (rash), ciprofloxacin (rash), and tigecycline (rash). The patient also reported previous reactions to aztreonam (unknown) and gentamicin (hives). The pharmacy was consulted to develop a desensitization protocol for ceftaroline. The desensitization protocol used three serial dilutions of ceftaroline to make 14 sequential infusions with escalating doses. Intramuscular epinephrine, i.v. diphenhydramine, and i.v. methylprednisolone were ordered as needed for the development of immediate hypersensitivity reactions during or after administration of ceftaroline. The cumulative dose (574.94 mg) was administered intravenously over 225 minutes with no breakthrough symptoms reported during or after the desensitization protocol. Ceftaroline fosamil 600 mg i.v. every 12 hours was continued for six weeks. Desensitization to ceftaroline was conducted for a patient with extensive history of hypersensitivity reactions to other drugs, including penicillin-induced anaphylaxis. Desensitization and subsequent treatment with full doses of ceftaroline were accomplished without apparent adverse effects. Copyright © 2015 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Detection of Extended-Spectrum β-Lactamases in Clinical Isolates of Enterobacter cloacae and Enterobacter aerogenes

PubMed Central

Tzelepi, Eva; Giakkoupi, Panagiota; Sofianou, Danai; Loukova, Veneta; Kemeroglou, Anastassia; Tsakris, Athanassios

2000-01-01

The aim of the present study was to investigate the frequency of extended-spectrum β-lactamases (ESBLs) in a consecutive collection of clinical isolates of Enterobacter spp. The abilities of various screening methods to detect ESBLs in enterobacters were simultaneously tested. Among the 68 consecutive isolates (56 Enterobacter cloacae and 12 Enterobacter aerogenes isolates) that were analyzed for β-lactamase content, 21 (25 and 58%, respectively) possessed transferable ESBLs with pIs of 8.2 and phenotypic characteristics of SHV-type enzymes, 8 (14.3%) of the E. cloacae isolates produced a previously nondescribed, clavulanate-susceptible ESBL that exhibited a pI of 6.9 and that conferred a ceftazidime resistance phenotype on Escherichia coli transconjugants, and 2 E. cloacae isolates produced both of these enzymes. Among the total of 31 isolates that were considered ESBL producers, the Vitek ESBL detection test was positive for 2 (6.5%) strains, and the conventional double-disk synergy test (DDST) with amoxicillin-clavulanate and with expanded-spectrum cephalosporins and aztreonam was positive for 5 (16%) strains. Modifications of the DDST consisting of closer application of the disks (at 20 instead of 30 mm), the use of cefepime, and the use of both modifications increased the sensitivity of this test to 71, 61, and 90%, respectively. Of the 37 isolates for which isoelectric focusing failed to determine ESBLs, the Vitek test was false positive for 1 isolate and the various forms of DDSTs were false-positive for 3 isolates. PMID:10655342

Biochemical Characterization of β-Lactamases from Mycobacterium abscessus Complex and Genetic Environment of the β-Lactamase-Encoding Gene.

PubMed

Ramírez, Ana; Ruggiero, Melina; Aranaga, Carlos; Cataldi, Angel; Gutkind, Gabriel; de Waard, Jacobus H; Araque, María; Power, Pablo

2017-04-01

The objectives of this study were to determine the kinetic parameters of purified recombinant Bla Mab and Bla Mmas by spectrophotometry, analyze the genetic environment of the bla Mab and bla Mmas genes in both species by polymerase chain reaction and sequencing, furthermore, in silico models of both enzymes in complex with imipenem were obtained by modeling tools. Our results showed that Bla Mab and Bla Mmas have a similar hydrolysis behavior, displaying high catalytic efficiencies toward penams, cephalothin, and nitrocefin; none of the enzymes are well inhibited by clavulanate. Bla Mmas hydrolyzes imipenem at higher efficiency than cefotaxime and aztreonam. Bla Mab and Bla Mmas showed that their closest structural homologs are KPC-2 and SFC-1, which correlate to the mild carbapenemase activity toward imipenem observed at least for BlaMmas. They also seem to differ from other class A β-lactamases by the presence of a more flexible Ω loop, which could impact in the hydrolysis efficiency against some antibiotics. A -35 consensus sequence (TCGACA) and embedded at the 3' end of MAB_2874, which may constitute the bla Mab and bla Mmas promoter. Our results suggest that the resistance mechanisms in fast-growing mycobacteria could be probably evolving toward the production of β-lactamases that have improved catalytic efficiencies against some of the drugs commonly used for the treatment of mycobacterial infections, endangering the use of important drugs like the carbapenems.

[Analysis of resistant genes of beta-lactam antibiotics from Pseudomonas aeruginosa in pediatric patients].

PubMed

Dong, Fang; Xu, Xi-wei; Song, Wen-qi; Lü, Ping; Yang, Yong-hong; Shen, Xu-zhuang

2008-11-18

To analyze the antibiotic resistance of the Pseudomonas aeruginosa (PA) isolated from pediatric patients and the resistant genes of beta-lactam antibiotics thereof. 146 PA strains were isolated from pediatric patients. Agar dilution method recommended by the Clinical and Laboratory Standards Institute was used to examine the minimum inhibitory concentrations (MICs) of 12 antimicrobial agents, including the penicillins, third and fourth genet ration cephalosporins, carbapenemase, Aztreonam, beta-lactamase inhibitors, quinolones, and aminoglycosides. PCR was used to detect the expression of the genes TEM, SHV, OXA, PER, GES, CTX-M, IMP, VIM, DHA, MIR, FOX, and oprD2. The multi-drug resistance rates against different antibiotic were high among the 146 PA strains. The rates of imipenem and meropenem resistance were 41.1% and 35.6% respectively. Among the 146 PA strains, 46 (31.5%) were positive for the MBL genotype; 38 (82.6%) carried the blaIMP gene, 8 (17.4%) carried the blaVIM gene, and 114 (78.1%) were oprD2 negative. The genes TEM, SHV, OXA, CTX-M, PER, VEB, GES, FOX, MIR, and DHA were not found in all strains. Many PA isolated from pediatric patients carry the genes IMP or VIM and losses oprD2 gene related to the expression of the outer membrane porin OprD2. The loss of the gene oprD2 is essential mechanism of beta-lactam antibiotics resistance in PA.

Activities of beta-lactam antibiotics against Escherichia coli strains producing extended-spectrum beta-lactamases.

PubMed Central

Jacoby, G A; Carreras, I

1990-01-01

Seven extended-spectrum beta-lactamases related to TEM and four enzymes derived from SHV-1 were transferred to a common Escherichia coli host so that the activity of a variety of beta-lactams could be tested in a uniform genetic environment. For most derivatives, penicillinase activity was 10% or less than that of strains making TEM-1, TEM-2, or SHV-1 beta-lactamase, suggesting that reduced catalytic efficiency accompanied the broader substrate spectrum. Despite this deficit, resistance to aztreonam, carumonam, cefdinir, cefepime, cefixime, cefmenoxime, cefotaxime, cefotiam, cefpirome, cefpodoxime, ceftazidime, ceftibuten, ceftizoxime, ceftriaxone, cefuroxime, and E1040 was enhanced. For strains producing TEM-type enzymes, however, MICs of carumonam, cefepime, cefmenoxime, cefotiam, cefpirome, and ceftibuten were 8 micrograms/ml or less. Susceptibilities of cefmetazole, cefotetan, cefoxitin, flomoxef, imipenem, meropenem, moxalactam, temocillin, FCE 22101, and Sch 34343 were unaffected. FCE 22101, imipenem, meropenem, and Sch 34343 were inhibitory for all strains at 1 microgram/ml or less. In E. coli an OmpF- porin mutation in combination with an extended-spectrum beta-lactamase enhanced resistance to many of these agents, but generally by only fourfold. Hyperproduction of chromosomal AmpC beta-lactamase increased resistance to 7-alpha-methoxy beta-lactams but not that to temocillin. When tested at 8 micrograms/ml, clavulanate was more potent than sulbactam or tazobactam in overcoming resistance to ampicillin, while cefoperazone-sulbactam was more active than ticarcillin-clavulanate or piperacillin-tazobactam, especially against TEM-type extended-spectrum beta-lactamases. PMID:2193623

Urinary tract infection by Acinetobacter baumannii and Pseudomonas aeruginosa: evolution of antimicrobial resistance and therapeutic alternatives.

PubMed

Jiménez-Guerra, Gemma; Heras-Cañas, Victor; Gutiérrez-Soto, Miguel; Del Pilar Aznarte-Padial, María; Expósito-Ruiz, Manuela; Navarro-Marí, José María; Gutiérrez-Fernández, José

2018-04-25

Acinetobacter baumannii and Pseudomonas aeruginosa are responsible for numerous nosocomial infections. The objective of this study was to determine the development of their susceptibility to ten antibiotics and the antibiotic consumption of patients with suspicion of urinary tract infection (UTI). A retrospective study was conducted on the susceptibility profiles of A. baumannii and P. aeruginosa isolates from 749 urine samples gathered between January 2013 and December 2016, and on the consumption of imipenem, meropenem and piperacillin-tazobactam between 2014 and 2016. Hospital patients were the source of 82 (91.1 %) of the 90 A. baumannii isolates detected and 555 (84.2 %) of the 659 P. aeruginosa isolates. Globally, the lowest percentage susceptibility values were found for fosfomycin, aztreonam and ciprofloxacin, while colistin continued to be the most active antibiotic in vitro. In 2016, the susceptibility of A. baumannii to carbapenem and piperacillin-tazobactam decreased to very low values, while the susceptibility of P. aeruginosa to carbapenem remained stable but its susceptibility to piperacillin-tazobactam decreased. There was a marked increase in the consumption of piperacillin-tazobactam. In our setting, it is no longer possible to use carbapenems and piperacillin-tazobactam for empirical treatment of UTI due to A. baumannii or to use piperacillin-tazobactam for empirical treatment of UTI due to P. aeruginosa. Colistin was found to be the most active antibiotic in vitro. There was a marked increase in the consumption of piperacillin-tazobactam.

Suppression of ciprofloxacin-induced resistant Pseudomonas aeruginosa in a dynamic kill curve system.

PubMed

Wu, Benjamin M; Sabarinath, Sreedharan N; Rand, Kenneth; Johnson, Judith; Derendorf, Hartmut

2011-06-01

Current dosing approaches for treating microbial infections ignore resistant subpopulations. A clinical isolate of Pseudomonas aeruginosa was cultured in a dynamic in vitro kill curve system designed to simulate the half-lives of drugs in order to evaluate the drug-microbial response relationship. The first dose of ciprofloxacin (CIP) uses a concentration equivalent to the unbound fraction of a 200mg clinical dose. A second dose of 200mg or 600 mg CIP, or ceftriaxone (CFX) or gentamicin (GEN) was administered at 12h. Dynamics of the minimum inhibitory concentration (MIC) were assessed using Etest strips before and throughout the CIP treatment period. In addition, the microbroth dilution method was used to evaluate drug susceptibility across a wide range of antibiotics using samples from before and after CIP exposure. A significant loss of CIP effects was observed at the second dose. Cross-resistance to many antibiotics (cefoxitin, cefuroxime, cefotetan, ampicillin and ertapenem) was observed. GEN, but not CFX or high-dose CIP, was sufficient to suppress the developed resistant subpopulation following the initial CIP exposure. The CIP MIC increased substantially from 0.13 μg/mL pre dose to 4 μg/mL at 12h after a CIP dose. In addition, aztreonam induced a similar resistance pattern as CIP, indicating that induction of resistance was not limited to fluoroquinolones. In conclusion, the in vitro dynamic kill curve system revealed that aminoglycosides, more than other classes of antibiotics, were effective against the CIP-induced resistant subpopulations. Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Clinical and economic outcomes from a community hospital's antimicrobial stewardship program.

PubMed

Malani, Anurag N; Richards, Patrick G; Kapila, Shikha; Otto, Michael H; Czerwinski, Jennifer; Singal, Bonita

2013-02-01

Data from community antimicrobial stewardship programs (ASPs) are limited. We describe clinical and economic outcomes from the first year of our hospital's ASP. The ASP team comprised 2 infectious disease physicians and 3 intensive care unit pharmacists. The team prospectively audited the new starts and weekly use of 8 target antimicrobials: aztreonam, caspofungin, daptomycin, ertapenem, linezolid, meropenem, tigecycline, and voriconazole. Using administrative data, outcomes from the first year of the program, including death within 30 days of hospitalization, readmission within 30 days of discharge, and development of Clostridium difficile infection (CDI), were compared with outcomes from a similar period before institution of the program. A total of 510 antimicrobial orders were reviewed, of which 323 (63%) were appropriate, 94 (18%) prompted deescalation, 61 (12%) were denied, and 27 (5%) led to formal consultation with an infectious disease physician. On multivariate analysis, implementation of the ASP was associated with an approximate 50% reduction in the odds of developing CDI (odds ratio, 0.46; 95% confidence interval, 0.25-0.82). The ASP was not associated with decreased mortality at 30 days after discharge or readmission rate. The antimicrobial cost per patient-day decreased by 13.3%, from $10.16 to $8.81. The antimicrobial budget decreased by 15.2%, resulting in a total savings of $228,911. There was a 25.4% decrease in defined daily doses of the target antimicrobials. Implementation of the ASP was associated with significant reductions in CDI rate, antimicrobial use, and pharmacy costs. Copyright © 2013 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Phenotypic and molecular characterization of antimicrobial resistance in Proteus mirabilis isolates from dogs.

PubMed

Harada, Kazuki; Niina, Ayaka; Shimizu, Takae; Mukai, Yujiro; Kuwajima, Ken; Miyamoto, Tadashi; Kataoka, Yasushi

2014-11-01

Large-scale monitoring of resistance to 14 antimicrobial agents was performed using 103 Proteus mirabilis strains isolated from dogs in Japan. Resistant strains were analysed to identify their resistance mechanisms. Rates of resistance to chloramphenicol, streptomycin, enrofloxacin, trimethoprim/sulfamethoxazole, kanamycin, ampicillin, ciprofloxacin, cephalothin, gentamicin, cefoxitin and cefotaxime were 20.4, 15.5, 12.6, 10.7, 9.7, 8.7, 5.8, 2.9, 2.9, 1.9 and 1.9%, respectively. No resistance to ceftazidime, aztreonam or imipenem was found. Class 1 and 2 integrases were detected in 2.9 and 11.7% of isolates, respectively. Class 1 integrons contained aadB or aadB-catB-like-blaOXA10-aadA1, whereas those of class 2 contained sat-aadA1, dhfr1-sat-aadA1 or none of the anticipated resistance genes. Of five distinct plasmid-mediated quinolone-resistance (PMQR) genes, only qnrD gene was detected in 1.9% of isolates. Quinolone-resistance determining regions (QRDRs) of gyrA and parC from 13 enrofloxacin-intermediate and -resistant isolates were sequenced. Seven strains had double mutations and three had single mutations. Three of nine ampicillin-resistant isolates harboured AmpC-type β-lactamases (i.e. blaCMY-2, blaCMY-4 and blaDHA-1). These results suggest that canine Proteus mirabilis deserves continued surveillance as an important reservoir of antimicrobial resistance determinants. This is the first report, to our knowledge, describing integrons, PMQRs and QRDR mutations in Proteus mirabilis isolates from companion animals. © 2014 The Authors.

Antibiotic sensitivity pattern of causative organisms of neonatal septicemia in an urban hospital of Bangladesh.

PubMed

Monjur, Forhad; Rizwan, Farhana; Asaduzzaman, Muhammad; Nasrin, Nishat; Ghosh, Nobo Krishna; Apu, Apurba Sarker; Haque, Fazlul

2010-06-01

The information of the sensitivity pattern of the causative organisms is very important for effective control of septicemia in neonates. To determine the proportion and profile of pathogenic bacteria in the blood cultures of the neonates with clinically suspected septicemia and their susceptibility pattern to antimicrobial agents for developing a unified antibiotic treatment protocol. A cross-sectional retrospective study was conducted over a period of 3 year and 4 months (39 months). The study included 1000 patients admitted in the selected hospital in Bangladesh. Blood samples for culture were taken aseptically before starting antibiotic therapy. Microorganisms were isolated and identified by standard microbiological processes which include colony morphology, Gram stain, and biochemical profiles. Antimicrobial sensitivity patterns were performed by Kirby-Bauer's disc diffusion method against imipenem, ciprofloxacin, ceftazidime, chloramphenicol, netilmicin, gentamicin, ceftriaxone, aztreonam, cefotaxime, cephalexin, and ampicillin. Among the patients, 633 (63.3%) were males and 367 (36.7%) were females. Blood cultures were found positive in 194 (19.4%) neonates. The organisms isolated were Pseudomonas spp. (31.4%), Klebsiella pneumoniae (23.2%), Staphylococcus aureus (12.4%), Escherichia coli (7.2%), Acinatobactor (5.7%), Gram-negative Bacilli (4.1%), Flavobacterium spp. (3.6%), Serratia spp. (5.7%), Citrobacter fruendi (3.1%), Streptococcus species (2.6%), and Enterobacter spp. (1.0%). A majority of the bacterial isolates in neonatal sepsis were found sensitive to imipenem (91.8%) and ciprofloxacin (57.2%) and resistant to commonly used antibiotics, eg. ampicillin (96.4%) and cephalexin (89.2%). The problem can be mitigated by careful selection and prudent use of available antibiotics.

Diagnosis and treatment of patients with prostatic abscess in the post-antibiotic era.

PubMed

Ackerman, Anne Lenore; Parameshwar, Pooja S; Anger, Jennifer T

2018-02-01

We reviewed the pathogenesis, clinical presentation, treatment options and outcomes of prostatic abscess in the post-antibiotic era, focusing on how patient risk factors and the emergence of multidrug-resistant organisms influence management of the condition. A MEDLINE search for "prostate abscess" or "prostatic abscess" was carried out. Prostate abscess is no longer considered a consequence of untreated urinary infection; now, men with prostatic abscess are typically debilitated or immunologically compromised, with >50% of patients having diabetes. In younger men, prostatic abscess can be the initial presentation of such chronic conditions. In older men, prostatic abscess is increasingly a complication of benign prostatic hyperplasia or prostate biopsy. Diagnosis is based on a physical examination, leukocytosis, leukocyturia and transrectal ultrasound, with magnetic resonance imaging serving as the preferred confirmatory imaging modality. Treatment of prostatic abscess is changing as a result of the emergence of atypical and drug-resistant organisms, such as extended-spectrum β-lactamase-producing enterobacteriaceae and methicillin-resistant Staphylococcus aureus. As many as 75% of infections are resistant to first-generation antibiotics, necessitating aggressive therapy with broad-spectrum parenteral antibiotics, such as third-generation cephalosporins, aztreonam or antibiotic combinations. A total of 80% of patients require early surgical drainage, frequently through a transurethral approach. In the post-antibiotic era, prostatic abscess is evolving from an uncommon complication of urinary infection to a consequence of immunodeficiency, growing antibiotic resistance and urological manipulation. This condition, primarily affecting patients with chronic medical conditions rendering them susceptible to atypical, drug-resistant organisms, requires prompt aggressive intervention with contemporary antibiotic therapy and surgical drainage. © 2017 The Japanese Urological Association.

Targeting the Nonmevalonate Pathway in Burkholderia cenocepacia Increases Susceptibility to Certain β-Lactam Antibiotics.

PubMed

Sass, Andrea; Everaert, Annelien; Van Acker, Heleen; Van den Driessche, Freija; Coenye, Tom

2018-05-01

The nonmevalonate pathway is the sole pathway for isoprenoid biosynthesis in Burkholderia cenocepacia and is possibly a novel target for the development of antibacterial chemotherapy. The goals of the present study were to evaluate the essentiality of dxr , the second gene of the nonmevalonate pathway, in B. cenocepacia and to determine whether interfering with the nonmevalonate pathway increases susceptibility toward antibiotics. To this end, a rhamnose-inducible conditional dxr knockdown mutant of B. cenocepacia strain K56-2 ( B. cenocepacia K56-2 dxr ) was constructed, using a plasmid which enables the delivery of a rhamnose-inducible promoter in the chromosome. Expression of dxr is essential for bacterial growth; the growth defect observed in the dxr mutant could be complemented by expressing dxr in trans under the control of a constitutive promoter, but not by providing 2- C -methyl-d-erythritol-4-phosphate, the reaction product of DXR (1-deoxy-d-xylulose 5-phosphate reductoisomerase). B. cenocepacia K56-2 dxr showed markedly increased susceptibility to the β-lactam antibiotics aztreonam, ceftazidime, and cefotaxime, while susceptibility to other antibiotics was not (or was much less) affected; this increased susceptibility could also be complemented by in trans expression of dxr A similarly increased susceptibility was observed when antibiotics were combined with FR900098, a known DXR inhibitor. Our data confirm that the nonmevalonate pathway is essential in B. cenocepacia and suggest that combining potent DXR inhibitors with selected β-lactam antibiotics is a useful strategy to combat B. cenocepacia infections. Copyright © 2018 American Society for Microbiology.

Avibactam and Class C β-Lactamases: Mechanism of Inhibition, Conservation of the Binding Pocket, and Implications for Resistance

PubMed Central

Johnstone, M. R.; Ross, P. L.; McLaughlin, R. E.; Olivier, N. B.

2014-01-01

Avibactam is a novel non-β-lactam β-lactamase inhibitor that inhibits a wide range of β-lactamases. These include class A, class C, and some class D enzymes, which erode the activity of β-lactam drugs in multidrug-resistant pathogens like Pseudomonas aeruginosa and Enterobacteriaceae spp. Avibactam is currently in clinical development in combination with the β-lactam antibiotics ceftazidime, ceftaroline fosamil, and aztreonam. Avibactam has the potential to be the first β-lactamase inhibitor that might provide activity against class C-mediated resistance, which represents a growing concern in both hospital- and community-acquired infections. Avibactam has an unusual mechanism of action: it is a covalent inhibitor that acts via ring opening, but in contrast to other currently used β-lactamase inhibitors, this reaction is reversible. Here, we present a high-resolution structure of avibactam bound to a class C β-lactamase, AmpC, from P. aeruginosa that provided insight into the mechanism of both acylation and recyclization in this enzyme class and highlighted the differences observed between class A and class C inhibition. Furthermore, variants resistant to avibactam that identified the residues important for inhibition were isolated. Finally, the structural information was used to predict effective inhibition by sequence analysis and functional studies of class C β-lactamases from a large and diverse set of contemporary clinical isolates (P. aeruginosa and several Enterobacteriaceae spp.) obtained from recent infections to understand any preexisting variability in the binding pocket that might affect inhibition by avibactam. PMID:25022578

Beta-lactams in continuous infusion for Gram-negative bacilli osteoarticular infections: an easy method for clinical use.

PubMed

Ribera, Alba; Soldevila, Laura; Rigo-Bonnin, Raul; Tubau, Fe; Padullés, Ariadna; Gómez-Junyent, Joan; Ariza, Javier; Murillo, Oscar

2018-04-01

Continuous infusion (CI) of beta-lactams could optimize their pharmacokinetic/pharmacodynamic indices, especially in difficult-to-treat infections. To validate an easy-to-use method to guide beta-lactams dosage in CI (formula). A retrospective analysis was conducted of a prospectively collected cohort (n = 24 patients) with osteoarticular infections caused by Gram-negative bacilli (GNB) managed with beta-lactams in CI. Beta-lactams dose was calculated using a described formula (daily dose = 24 h × beta-lactam clearance × target "steady-state" concentration) to achieve concentrations above the MIC. We correlated the predicted concentration (C pred  = daily dose/24 h × beta-lactam clearance) with the patient's observed concentration (C obs ) measured by UPLC-MS/MS (Spearman's coefficient). The most frequent microorganism treated was P. aeruginosa (21 cases; 9 MDR). Beta-lactams in CI were ceftazidime (n = 14), aztreonam (7), and piperacillin/tazobactam (3), mainly used in combination (12 with colistin, 5 with ciprofloxacin) and administered without notable side effects. The plasma C obs was higher overall than C pred ; the Spearman correlation between both concentrations was rho = 0.6 (IC 95%: 0.2-0.8) for all beta-lactams, and rho = 0.8 (IC 95%: 0.4-1) for those treated with ceftazidime. The formula may be useful in clinical practice for planning the initial dosage of beta-lactams in CI, while we await a systematic therapeutic drug monitoring. The use of beta-lactams in CI was safe.

Antimicrobial Resistance Pattern and Their Beta-Lactamase Encoding Genes among Pseudomonas aeruginosa Strains Isolated from Cancer Patients

PubMed Central

Zafer, Mai M.; Al-Agamy, Mohamed H.; El-Mahallawy, Hadir A.; Amin, Magdy A.; Ashour, Mohammed Seif El-Din

2014-01-01

This study was designed to investigate the prevalence of metallo-β-lactamases (MBL) and extended-spectrum β-lactamases (ESBL) in P. aeruginosa isolates collected from two different hospitals in Cairo, Egypt. Antibiotic susceptibility testing and phenotypic screening for ESBLs and MBLs were performed on 122 P. aeruginosa isolates collected in the period from January 2011 to March 2012. MICs were determined. ESBLs and MBLs genes were sought by PCR. The resistant rate to imipenem was 39.34%. The resistance rates for P. aeruginosa to cefuroxime, cefoperazone, ceftazidime, aztreonam, and piperacillin/tazobactam were 87.7%, 80.3%, 60.6%, 45.1%, and 25.4%, respectively. Out of 122 P. aeruginosa, 27% and 7.4% were MBL and ESBL, respectively. The prevalence of bla VIM-2, bla OXA-10-, bla VEB-1, bla NDM-, and bla IMP-1-like genes were found in 58.3%, 41.7%, 10.4%, 4.2%, and 2.1%, respectively. GIM-, SPM-, SIM-, and OXA-2-like genes were not detected in this study. OXA-10-like gene was concomitant with VIM-2 and/or VEB. Twelve isolates harbored both OXA-10 and VIM-2; two isolates carried both OXA-10 and VEB. Only one strain contained OXA-10, VIM-2, and VEB. In conclusion, bla VIM-2- and bla OXA-10-like genes were the most prevalent genes in P. aeruginosa in Egypt. To our knowledge, this is the first report of bla VIM-2, bla IMP-1, bla NDM, and bla OXA-10 in P. aeruginosa in Egypt. PMID:24707471

Inhaled Antibiotics for Lower Airway Infections

PubMed Central

Quon, Bradley S.; Goss, Christopher H.

2014-01-01

Inhaled antibiotics have been used to treat chronic airway infections since the 1940s. The earliest experience with inhaled antibiotics involved aerosolizing antibiotics designed for parenteral administration. These formulations caused significant bronchial irritation due to added preservatives and nonphysiologic chemical composition. A major therapeutic advance took place in 1997, when tobramycin designed for inhalation was approved by the U.S. Food and Drug Administration (FDA) for use in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa infection. Attracted by the clinical benefits observed in CF and the availability of dry powder antibiotic formulations, there has been a growing interest in the use of inhaled antibiotics in other lower respiratory tract infections, such as non-CF bronchiectasis, ventilator-associated pneumonia, chronic obstructive pulmonary disease, mycobacterial disease, and in the post–lung transplant setting over the past decade. Antibiotics currently marketed for inhalation include nebulized and dry powder forms of tobramycin and colistin and nebulized aztreonam. Although both the U.S. Food and Drug Administration and European Medicines Agency have approved their use in CF, they have not been approved in other disease areas due to lack of supportive clinical trial evidence. Injectable formulations of gentamicin, tobramycin, amikacin, ceftazidime, and amphotericin are currently nebulized “off-label” to manage non-CF bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Future inhaled antibiotic trials must focus on disease areas outside of CF with sample sizes large enough to evaluate clinically important endpoints such as exacerbations. Extrapolating from CF, the impact of eradicating organisms such as P. aeruginosa in non-CF bronchiectasis should also be evaluated. PMID:24673698

Inhaled antibiotics for lower airway infections.

PubMed

Quon, Bradley S; Goss, Christopher H; Ramsey, Bonnie W

2014-03-01

Inhaled antibiotics have been used to treat chronic airway infections since the 1940s. The earliest experience with inhaled antibiotics involved aerosolizing antibiotics designed for parenteral administration. These formulations caused significant bronchial irritation due to added preservatives and nonphysiologic chemical composition. A major therapeutic advance took place in 1997, when tobramycin designed for inhalation was approved by the U.S. Food and Drug Administration (FDA) for use in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa infection. Attracted by the clinical benefits observed in CF and the availability of dry powder antibiotic formulations, there has been a growing interest in the use of inhaled antibiotics in other lower respiratory tract infections, such as non-CF bronchiectasis, ventilator-associated pneumonia, chronic obstructive pulmonary disease, mycobacterial disease, and in the post-lung transplant setting over the past decade. Antibiotics currently marketed for inhalation include nebulized and dry powder forms of tobramycin and colistin and nebulized aztreonam. Although both the U.S. Food and Drug Administration and European Medicines Agency have approved their use in CF, they have not been approved in other disease areas due to lack of supportive clinical trial evidence. Injectable formulations of gentamicin, tobramycin, amikacin, ceftazidime, and amphotericin are currently nebulized "off-label" to manage non-CF bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Future inhaled antibiotic trials must focus on disease areas outside of CF with sample sizes large enough to evaluate clinically important endpoints such as exacerbations. Extrapolating from CF, the impact of eradicating organisms such as P. aeruginosa in non-CF bronchiectasis should also be evaluated.

Prevalence and virulence characteristics of enteroaggregative Escherichia coli in a case-control study among patients from Iran.

PubMed

Bafandeh, Saeed; Haghi, Fakhri; Zeighami, Habib

2015-05-01

Enteroaggregative Escherichia coli (EAEC) is an important agent of diarrhoeal diseases worldwide. The role of EAEC virulence factors in the clinical outcome of infection is not completely defined. This case-control study investigated the prevalence of EAEC, its virulence genes and the antimicrobial resistance profile of adult patients with and without diarrhoea attending three different hospitals in Zanjan, Iran. A total of 550 individual stool specimens (350 from diarrhoeal patients and 200 from patients without diarrhoea) were collected. One hundred and forty-one EAEC isolates were identified by a HEp-2 cell assay and PCR. EAEC isolates were detected with slightly higher frequency in patients with (27.7%) than in patients without (22%) diarrhoea (P ≥ 0.05). The EAEC genes aggR, aap and pet were identified more frequently in case patients compared with controls (P ≤ 0.05). Many of the EAEC isolates from the diarrhoeal patients had two or more virulence genes compared with those without diarrhoea (P ≤ 0.05). EAEC isolates exhibited high-level resistance to amoxicillin (82.3%), co-amoxiclav (78%), aztreonam (73.8%), tetracycline (66.6%) and ceftazidime (63.8%). In addition, 53.2% of isolates were resistant to at least three different classes of antimicrobial agents and were considered to be multidrug resistant. These results indicate a high prevalence and heterogeneity of gene profiles of EAEC in diarrhoeal and control patients, and suggest that the presence of aggR, aap and pet, the number of genes present and the antimicrobial resistance profile may be markers for more-virulent EAEC isolates. © 2015 The Authors.

Changing trends in clinical characteristics and antibiotic susceptibility of Klebsiella pneumoniae bacteremia.

PubMed

Hyun, Miri; Noh, Chang In; Ryu, Seong Yeol; Kim, Hyun Ah

2018-05-01

Klebsiella pneumoniae is second most common organism of gram-negative bacteremia in Korea and one of the most common cause of urinary tract infection, and intra-abdominal infection. We compared clinical and microbiological characteristics about K. pneumoniae bacteremia in a tertiary hospital between 10 years. Group A is who had K. pneumoniae bacteremia at least one time from January 2004 to December 2005. Group B is from January 2012 to December 2013. We also analyzed antibiotic resistance, clinical manifestation of the K. pneumoniae bacteremia divided into community-acquired infections, healthcare associated infections, and nosocomial infections. The resistance for ampicillin, aztreonam, cefazolin, and cefotaxime significantly increased compared to 10 years ago. Extended spectrum β-lactamase positivity surged from 4.3% to 19.6%. Ten years ago, 1st, 2nd cephalosporin, and aminoglycoside were used more as empirical antibiotics. But these days, empirical antibiotics were broad spectrum such as 3rd and 4th cephalosporin. In treatment outcome, acute kidney injury decreased from 47.5% to 28.7%, and mortality decreased from 48.9% to 33.2%. In community-acquired infections, there was similar in antimicrobial resistance and mortality. In healthcare-associated and nosocomial infections, there was significantly increasing in antibiotic resistance, decreasing in mortality, and acute kidney injury. In community-acquired infections, broader antibiotics were more used than 10 years ago despite of similar antimicrobial resistance. When K. pneumoniae bacteremia is suspected, we recommend to use the narrow spectrum antibiotics as initial therapy if there are no healthcare-associated risk factors, because the antibiotic resistance is similar to 10 years ago in community-acquired infections.

Identification of "Haematobacter," a new genus of aerobic Gram-negative rods isolated from clinical specimens, and reclassification of Rhodobacter massiliensis as "Haematobacter massiliensis comb. nov.".

PubMed

Helsel, Leta O; Hollis, Dannie; Steigerwalt, Arnold G; Morey, Roger E; Jordan, Jean; Aye, Tin; Radosevic, Jon; Jannat-Khah, Deanna; Thiry, Dorothy; Lonsway, David R; Patel, Jean B; Daneshvar, Maryam I; Levett, Paul N

2007-04-01

Twelve strains of gram-negative, nonfermenting rods recovered mainly from septicemic patients were studied using conventional and molecular methods. The phenotypic profiles of these strains most closely resembled Psychrobacter phenylpyruvicus. They produced catalase, oxidase, urease, and H(2)S (lead acetate paper) but did not produce indole, reduce nitrate or nitrite, or hydrolyze gelatin or esculin. No acid production was observed in a King's oxidation-fermentation base containing d-glucose, d-xylose, d-mannitol, sucrose, lactose, or maltose. All strains were nonmotile and nonpigmented. Most strains produced green discoloration on blood agar. All strains grew at 25 degrees C and 35 degrees C and most grew on MacConkey agar. They shared a common cellular fatty acid (CFA) profile characterized by large amounts (56% to 90%) of 18:1omega7c and the presence of 3-OH-10:0, 16:1omega7c, 16:0, and 19:0cycomega8c that overall was most similar to that of Rhodobacter species but was quite distinct from that of P. phenylpyruvicus. The MICs for most beta-lactams, fluoroquinolones, aminoglycosides, and carbapenems were low. MICs for aztreonam and piperacillin were higher, with MICs for some strains of > 64 mg/liter and > 128 mg/liter, respectively. Polyphasic analysis of these strains, including morphological, biochemical, CFA composition, DNA-DNA hybridization, 16S rRNA gene sequencing, and percent guanine-plus-cytosine (G+C) content analysis, demonstrated that these strains and Rhodobacter massiliensis represent a new genus, "Haematobacter" (proposed name), with the species H. missouriensis (type strain H1892(T) = CCUG 52307(T) = CIP 109176(T)) and H. massiliensis comb. nov. (type strain Framboise(T) = CCUG 47968(T) = CIP 107725(T)) and an unnamed genomospecies.

Profile of Virulence Factors in the Multi-Drug Resistant Pseudomonas aeruginosa Strains of Human Urinary Tract Infections (UTI).

PubMed

Habibi, Asghar; Honarmand, Ramin

2015-12-01

Putative virulence factors are responsible for the pathogenicity of UTIs caused by Pseudomonas aeruginosa (P. aeruginosa). Resistance of P. aeruginosa to commonly used antibiotics is caused by the extreme overprescription of those antibiotics. The goal of the present study was to investigate the prevalence of virulence factors and the antibiotic resistance patterns of P. aeruginosa isolates in UTI cases in Iran. Two hundred and fifty urine samples were collected from patients who suffered from UTIs. Samples were cultured immediately, and those that were P. aeruginosa-positive were analyzed for the presence of virulence genes using polymerase chain reaction (PCR) testing. Antimicrobial susceptibility testing (AST) was performed using the disk diffusion method. Of the 250 urine samples analyzed, 8 samples (3.2%) were positive for P. aeruginosa. The prevalence of P. aeruginosa in male and female patients was 2.7% and 3.5%, respectively, (P = 0.035). In patients less than 10 years old, it was 4.2%, and in patients more than 55 years old, it was 4.2%. These were the most commonly infected groups. The highest levels of resistance were seen against ampicillin (87.5%), norfloxacin (62.5%), gentamycin (62.5%), amikacin (62.5%), and aztreonam (62.5%), while the lowest were seen for meropenem (0%), imipenem (12.5%), and polymyxin B (12.5%). LasB (87.5%), pclH (75%), pilB (75%), and exoS (75%) were the most commonly detected virulence factors in the P. aeruginosa isolates. It is logical to first prescribe meropenem, imipenem, and polymyxin B in cases of UTIs caused by P. aeruginosa. Medical practitioners should be aware of the presence of levels of antibiotic resistance in hospitalized UTI patients in Iran.

Prevalence of AmpC and other beta-lactamases in enterobacteria at a large urban university hospital in Brazil

PubMed Central

Dias, Rubens Clayton da Silva; Borges-Neto, Armando Alves; Ferraiuoli, Giovanna Ianini D’Almeida; de-Oliveira, Márcia P.; Riley, Lee W.; Moreira, Beatriz Meurer

2010-01-01

Production of extended-spectrum β-lactamases (ESBL) has been reported in virtually all species of Enterobacteriaceae, which greatly complicates the therapy of infections caused by these organisms. However, the frequency of isolates producing AmpC β-lactamases, especially plasmid mediated AmpC (pAmpC), is largely unknown. These β-lactamases confer resistance to extended spectrum cephalosporins and aztreonam, a multidrug-resistant (MDR) profile. The aim of the present study was to determine the occurrence of ESBL and pAmpC β-lactamases in a hospital where MDR enterobacterial isolates recently emerged. A total of 123 consecutive enterobacterial isolates obtained from 112 patients at a university hospital in Rio de Janeiro, Brazil during March-June 2001 were included in the study. ESBL was detected by the addition of clavulanate to cephalosporin containing disks and by double diffusion. AmpC production was evaluated by a modified tridimensional test and a modified Hodge test. The presence of plasmid-mediated ampC β-lactamase genes was evaluated by multiplex-PCR. Sixty-five (53%) of 123 enterobacterial isolates were MDR, obtained from 56 patients. ESBL production was detected in 35 isolates; 5 clonal E. coli isolates exhibited high levels of chromosomal AmpC and ESBL production. However, no isolates contained pAmpC genes. Infection or colonization by MDR enterobacteria was not associated with any predominant resistant clones. A large proportion of hospital infections caused by ESBL-producing enterobacteria identified during the study period were due to sporadic infections rather than undetected outbreaks. This observation emphasizes the need to improve our detection methods for ESBL- and AmpC-producing organisms in hospitals where extended-spectrum cephalosporins are in wide use. PMID:17900845

Antimicrobial resistance and phylogenetic groups in isolates of Escherichia coli from seagulls at the Berlengas nature reserve.

PubMed

Radhouani, H; Poeta, P; Igrejas, G; Gonçalves, A; Vinué, L; Torres, C

2009-08-01

Fifty-three faecal samples from yellow-legged gulls (Larus cachinnans) at the Berlengas nature reserve in Portugal were cultured on Levine agar plates not supplemented with antimicrobial agents, and one Escherichia coli colony was isolated and identified from each sample. The percentages of resistant isolates for each of the drugs were ampicillin (43.4 per cent), tetracycline (39.6 per cent), nalidixic acid (34.0 per cent), streptomycin (32.1 per cent), trimethoprim-sulfamethoxazole (SXT) (26.4 per cent), ciprofloxacin (18.9 per cent), chloramphenicol (18.9 per cent), gentamicin (7.5 per cent), tobramycin (7.5 per cent) amikacin (5.7 per cent) and amoxicillin-clavulanic acid (1.9 per cent). All the isolates were susceptible to cefoxitin, ceftazidime, cefotaxime, aztreonam and imipenem. The following resistance genes were detected: bla(TEM) (17 of 23 ampicillin-resistant isolates), tet(A) and/or tet(B) (18 of 21 tetracycline-resistant isolates), aadA (12 of 17 streptomycin-resistant isolates), cmlA (all chloramphenicol-resistant isolates), aac(3)-II with or without aac(3)-IV (all four gentamicin-resistant isolates), and sul1 and/or sul2 and/or sul3 (all 14 SXT-resistant isolates). The intI1 gene was detected in 10 of 14 SXT-resistant isolates, and three of them also contained class 2 integrons; four different gene cassette arrangements were identified among class 1 integrons (aadA, dfrA1+aadA1, dfrA12+orfF+aadA2 and sat+psp+aadA2) and one among the class 2 integrons (dfrA1+sat+aadA1). Ninety per cent of the isolates were included in the A or B1 phylogenetic groups.

The Use of Telemedicine for Penicillin Allergy Skin Testing.

PubMed

Staicu, Mary L; Holly, Anne Marie; Conn, Kelly M; Ramsey, Allison

2018-05-08

Penicillin skin testing (PST) is increasingly used as a tool to evaluate penicillin allergy in patients with a reported history. The limited availability of allergists, however, may be an impeding factor. We sought to assess the clinical utility of telemedicine to facilitate PST. Penicillin-allergic inpatients receiving systemic antibiotics were prospectively identified between April and August 2017. Qualifying patients underwent PST performed by a trained allergy/immunology physician assistant (PA). On completion of PST, a telemedicine consultation, through the use of real-time interactive video conferencing (Microsoft Lync 2013, Redmond, Wash), was performed remotely by an allergist. Patients were surveyed regarding their satisfaction with the telemedicine experience. Fifty patients consented to PST through a telemedicine consultation. The average total time to complete a consultation was 128 minutes (standard deviation [SD] ± 33). Of this, the average PA travel time was 46 minutes (36%) with the remaining time spent on clinical services (82 minutes, 64%). The average physician telemedicine time per patient was 5 minutes (SD ± 2). Patients rated their experience as an average of 4.5 on a scale of 1 (highly unsatisfied) to 5 (highly satisfied). Of the 46 PST-negative patients, 33 were transitioned to a β-lactam antibiotic that reduced the use of vancomycin, metronidazole, aztreonam, aminoglycosides, and clindamycin (P < .05). More than $30,000 was saved throughout the study period. Telemedicine is an effective and novel approach to facilitate PST in the inpatient setting and carries a high degree of patient satisfaction. This method has the potential to optimize and improve access to allergy/immunology resources. Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Microbiologic Analysis of Complicated and Uncomplicated Acute Appendicitis.

PubMed

García-Marín, Andrés; Pérez-López, Mercedes; Martínez-Guerrero, Elena; Rodríguez-Cazalla, Lorena; Compañ-Rosique, Antonio

2018-01-01

Microbiologic studies suggest that complicated (CAA) and uncomplicated (UAA) acute appendicitis are different entities. Routine peritoneal fluid cultures continue to be controversially related to a low positive rate, found mainly in UAA; to isolation of typical micro-organisms with expected susceptibilities; and to a community-acquired intra-abdominal infection. The aim of this study was to describe microbiologic isolates in CAA and UAA and the usefulness of peritoneal fluid cultures to determine the susceptibilities to our antibiotic therapy guidelines. This study was a retrospective review of a prospective database collected at University San Juan Hospital (Spain) between June 2014 and June 2017. Complicated acute appendicitis was defined as gangrenous or perforated, whereas UAA was defined as phegmonous or suppurative. Our antibiotic recommendations are amoxicillin-clavulanic acid and in patients with β-lactam allergies, metronidazole plus aztreonam, and an aminoglycoside (gentamicin or tobramycin). Microbiologic cultures were performed in 264 patients, 157 with a CAA and 107 with a UAA. The positive culture rate was significantly higher in CAA (59%) than in UAA (24.3%). Gram-positive cocci (51.6% CAA; 23.1% UAA), including Streptococcus constellatus (29% CAA; 3.8% UAA), and anaerobes (67.7% CAA; 42.3% UAA) were significantly more common in CAA. The rates of antibiotic resistance were amoxicillin-clavulanic acid 14% (17.2% CAA; 3.8% UAA), gentamicin or tobramycin 8.4% (9.7% CAA; 3.8% UAA), ciprofloxacin 5.9% (6.5% CAA; 3.8% UAA), and ertapenem 10.9% (14% CAA; 0 UAA). The culture-positive rate was higher in CAA, with different isolates and susceptibilities than in UAA, identifying a higher frequency of gram-positive cocci (including S. constellatus) and anaerobes. We recommend obtaining peritoneal fluid cultures in CAA, which frequently will lead to a change in the antimicrobial drug therapy guidelines, creating specific recommendations in AA.

Multiple substitutions lead to increased loop flexibility and expanded specificity in Acinetobacter baumannii carbapenemase OXA-239.

PubMed

Harper, Thomas M; June, Cynthia M; Taracila, Magdalena A; Bonomo, Robert A; Powers, Rachel A; Leonard, David A

2018-01-11

OXA-239 is a class D carbapenemase isolated from an Acinetobacter baumannii strain found in Mexico. This enzyme is a variant of OXA-23 with three amino acid substitutions in or near the active site. These substitutions cause OXA-239 to hydrolyze late-generation cephalosporins and the monobactam aztreonam with greater efficiency than OXA-23. OXA-239 activity against the carbapenems doripenem and imipenem is reduced ∼3-fold and 20-fold, respectively. Further analysis demonstrated that two of the substitutions (P225S and D222N) are largely responsible for the observed alteration of kinetic parameters, while the third (S109L) may serve to stabilize the protein. Structures of OXA-239 with cefotaxime, doripenem and imipenem bound as acyl-intermediates were determined. These structures reveal that OXA-239 has increased flexibility in a loop that contains P225S and D222N. When carbapenems are bound, the conformation of this loop is essentially identical with that observed previously for OXA-23, with a narrow active site that makes extensive contacts to the ligand. When cefotaxime is bound, the loop can adopt a different conformation that widens the active site to allow binding of that bulky drug. This alternate conformation is made possible by P225S and further stabilized by D222N. Taken together, these results suggest that the three substitutions were selected to expand the substrate specificity profile of OXA-23 to cephalosporins and monobactams. The loss of activity against imipenem, however, suggests that there may be limits to the plasticity of class D enzymes with regard to evolving active sites that can effectively bind multiple classes of β-lactam drugs. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Experimental design and modelling approach to evaluate efficacy of β-lactam/β-lactamase inhibitor combinations.

PubMed

Sy, S K B; Derendorf, H

2017-07-29

A β-lactamase inhibitor (BLI) confers susceptibility of β-lactamase-expressing multidrug resistant (MDR) organisms to the partnering β-lactam (BL). To discuss the experimental design and modelling strategies for two-drug combinations, using ceftazidime- and aztreonam-avibactam combinations, as examples. The information came from several publications on avibactam in vitro time-kill studies and corresponding pharmacodynamic models. The experimental design to optimally gather crucial information from constant-concentration time-kill studies is to use an agile matrix of two-drug concentration combinations that cover 0.25- to 4-fold BL minimum inhibitory concentration (MIC) relative to the BLI concentrations to be tested against the particular isolate. This shifting agile design can save substantial costs and resources, without sacrificing crucial information needed for model development. The complex synergistic BL/BLI interaction is quantitatively explored using a semi-mechanistic pharmacokinetic-pharmacodynamic (PK/PD) mathematical model that accounts for antimicrobial activities in the combination, bacteria-mediated BL degradation and inhibition of BL degradation by BLI. A predictive mathematical formulation for the two-drug killing effects preserves the correlation between the model-derived EC 50 of BL and the BL MIC. The predictive value of PK/PD model is evaluated against external data that were not used for model development, including but not limited to in vitro hollow fibre and in vivo murine infection models. As a framework for translational predictions, the goal of this modelling strategy is to significantly decrease the decision-making time by running clinical trial simulations with MIC-substituted EC 50 function for isolates of comparable susceptibility through established correlation between BL MIC and EC 50 values. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Cluster-distinguishing genotypic and phenotypic diversity of carbapenem-resistant Gram-negative bacteria in solid-organ transplantation patients: a comparative study.

PubMed

Karampatakis, Theodoros; Geladari, Anastasia; Politi, Lida; Antachopoulos, Charalampos; Iosifidis, Elias; Tsiatsiou, Olga; Karyoti, Aggeliki; Papanikolaou, Vasileios; Tsakris, Athanassios; Roilides, Emmanuel

2017-07-31

Solid-organ transplant recipients may display high rates of colonization and/or infection by multidrug-resistant bacteria. We analysed and compared the phenotypic and genotypic diversity of carbapenem-resistant (CR) strains of Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii isolated from patients in the Solid Organ Transplantation department of our hospital. Between March 2012 and August 2013, 56 CR strains from various biological fluids underwent antimicrobial susceptibility testing with VITEK 2, molecular analysis by PCR amplification and genotypic analysis with pulsed-field gel electrophoresis (PFGE). They were clustered according to antimicrobial drug susceptibility and genotypic profiles. Diversity analyses were performed by calculating Simpson's diversity index and applying computed rarefaction curves.Results/Key findings. Among K. pneumoniae, KP-producers predominated (57.1 %). VIM and OXA-23 carbapenemases prevailed among P. aeruginosa and A. baumannii (89.4 and 88.9 %, respectively). KPC-producing K. pneumoniae and OXA-23 A. baumannii were assigned in single PFGE pulsotypes. VIM-producing P. aeruginosa generated multiple pulsotypes. CR K. pneumoniae strains displayed phenotypic diversity in tigecycline, colistin (CS), amikacin (AMK), gentamicin (GEN) and co-trimoxazole (SXT) (16 clusters); P. aeruginosa displayed phenotypic diversity in cefepime (FEP), ceftazidime, aztreonam, piperacillin, piperacillin-tazobactam, AMK, GEN and CS (9 clusters); and A. baumannii displayed phenotypic diversity in AMK, GEN, SXT, FEP, tobramycin and rifampicin (8 clusters). The Simpson diversity indices for the interpretative phenotype and PFGE analysis were 0.89 and 0.6, respectively, for K. pneumoniae strains (P<0.001); 0.77 and 0.6 for P. aeruginosa (P=0.22); and 0.86 and 0.19 for A. baumannii (P=0.004). The presence of different antimicrobial susceptibility profiles does not preclude the possibility that two CR K. pneumoniae or A. baumannii isolates are clonally related.

blaNDM-21, a new variant of blaNDM in an Escherichia coli clinical isolate carrying blaCTX-M-55 and rmtB.

PubMed

Liu, Lu; Feng, Yu; McNally, Alan; Zong, Zhiyong

2018-06-14

New Delhi MBL (NDM) is a type of carbapenemase; 20 variants of NDM have been identified to date. We have found a new variant of NDM, NDM-21, and describe it here. A carbapenem-resistant Escherichia coli was subjected to WGS using an Illumina X10 sequencer to identify the antimicrobial resistance genes and its ST. The gene encoding the new variant of NDM was cloned into E. coli DH5α, with blaNDM-5 being cloned as the control. Transformants were tested for susceptibility to carbapenems. Mating was performed to obtain the plasmid carrying the new blaNDM gene and the complete plasmid sequence was obtained using long-read MinION sequencing. The E. coli isolate belonged to ST617 and phylogenetic group A. It had a gene encoding NDM-21, a new NDM variant. NDM-21 differs from NDM-5 by a Gly-to-Ser amino acid substitution at position 69 (G69S). NDM-21 retains the same activity against carbapenems as NDM-5. blaNDM-21 is carried by a 46.1 kb IncX3 plasmid, which is self-transmissible, and is located in a complex genetic context as blaNDM-5. The isolate also carried blaCTX-M-55, which encodes an ESBL conferring resistance to aztreonam (which completed its resistance to all clinically available β-lactams), and rmtB, which mediates high-level resistance to aminoglycosides, on an IncFII plasmid. A new NDM variant has been identified and blaNDM-21 has evolved from blaNDM-5 on an IncX3 plasmid.

Prevalence of methicillin-resistant Staphylococcus aureus in meat.

PubMed

de Boer, E; Zwartkruis-Nahuis, J T M; Wit, B; Huijsdens, X W; de Neeling, A J; Bosch, T; van Oosterom, R A A; Vila, A; Heuvelink, A E

2009-08-31

Recently the isolation of methicillin-resistant Staphylococcus aureus (MRSA) strains from several food-producing animals has been reported. During slaughtering of MRSA-positive animals, contamination of carcasses with MRSA may occur and consequently the meat of these animals may get contaminated. The aim of this study was to estimate the prevalence of MRSA in raw meat samples from the retail trade. Samples of raw beef, pork, veal, lamb/mutton, chicken, turkey, fowl and game were collected from the retail trade. A detection method including a two-step enrichment in Mueller-Hinton broth+6.5% NaCl and phenol red mannitol broth containing ceftizoxime and aztreonam, followed by isolation on MRSA ID agar (bioMérieux) was evaluated and subsequently applied for the detection of MRSA in samples of raw meats. MRSA strains were isolated from 264 (11.9%) of 2217 samples analyzed. Isolation percentages for the meat species were: beef (10.6%), veal (15.2%), lamb and mutton (6.2%), pork (10.7%), chicken (16.0%), turkey (35.3%), fowl (3.4%) and game (2.2%). The majority (85%) of the isolated strains belonged to spa-types of pulsed-field gel electrophoresis (PFGE) non-typeable (NT)-MRSA, corresponding to the multilocus sequence type ST398, a type also recently isolated in the Netherlands from pigs. However, a smaller part of these strains were found to be of other ST's, possibly of human origin. Further studies are needed to elucidate transmission routes of MRSA in relation to meat and other foods and to provide the tools for preventing the spread of MRSA. At present the high prevalence of MRSA in meat has not been shown to contribute significantly to the dissemination of MRSA to humans and the possible health hazard for consumers of the presence of MRSA in foods should be further elucidated.

Carbapenem Susceptibility and Multidrug-Resistance in Pseudomonas aeruginosa Isolates in Egypt

PubMed Central

Hashem, Hany; Hanora, Amro; Abdalla, Salah; Shawky, Alaa; Saad, Alaa

2016-01-01

Background Resistant Pseudomonas aeruginosa is a serious concern for antimicrobial therapy, as the common isolates exhibit variable grades of resistance, involving beta-lactamase enzymes, beside native defense mechanisms. Objectives The present study was designed to determine the occurrence of Metallo-β- Lactamases (MBL) and Amp C harboring P. aeruginosa isolates from Suez Canal university hospital in Ismailia, Egypt. Methods A total of 147 P. aeruginosa isolates, recovered from 311 patients during a 10-month period, were collected between May 2013 and February 2014; the isolates were collected from urine, wound and sputum. Minimum inhibitory concentration (MIC) determined by agar dilution methods was ≥2 μg/mL for meropenem and imipenem. Identification of P. aeruginosa was confirmed using API 20NE. Metallo-β- Lactamases and Amp C were detected based on different phenotypic methods. Results Overall, 26.5% of P. aeruginosa isolates (39/147) were carbapenem resistant isolates. Furthermore, 64.1% (25/39) were MBL producers, these isolates were screened by the combined disc and disc diffusion methods to determine the ability of MBL production. Both MBL and Amp C harbored P. aeruginosa isolates were 28% (7/25). Sixty-four percent of P. aeruginosa isolates were multidrug resistant (MDR) (16/25). The sensitivity toward polymyxin, imipenem, norfloxacin, piperacillin-tazobactam and gentamicin was 99%, 91%, 88%, 82% and 78%, respectively. The resistance rate towards cefotaxime, ceftazidime, cefepime, aztreonam and meropenem was 98.6%, 86%, 71.4%, 34% and 30%, respectively. Conclusions Multidrug resistance was significantly associated with MBL production in P. aeruginosa. Early detection of MBL-producing P. aeruginosa and hospital antibiotic policy prescription helps proper antimicrobial therapy and avoidance of dissemination of these multidrug resistance isolates. PMID:28138370

Carbapenem Susceptibility and Multidrug-Resistance in Pseudomonas aeruginosa Isolates in Egypt.

PubMed

Hashem, Hany; Hanora, Amro; Abdalla, Salah; Shawky, Alaa; Saad, Alaa

2016-11-01

Resistant Pseudomonas aeruginosa is a serious concern for antimicrobial therapy, as the common isolates exhibit variable grades of resistance, involving beta-lactamase enzymes, beside native defense mechanisms. The present study was designed to determine the occurrence of Metallo-β- Lactamases (MBL) and Amp C harboring P. aeruginosa isolates from Suez Canal university hospital in Ismailia, Egypt. A total of 147 P. aeruginosa isolates, recovered from 311 patients during a 10-month period, were collected between May 2013 and February 2014; the isolates were collected from urine, wound and sputum. Minimum inhibitory concentration (MIC) determined by agar dilution methods was ≥2 μg/mL for meropenem and imipenem. Identification of P. aeruginosa was confirmed using API 20NE. Metallo-β- Lactamases and Amp C were detected based on different phenotypic methods. Overall, 26.5% of P. aeruginosa isolates (39/147) were carbapenem resistant isolates. Furthermore, 64.1% (25/39) were MBL producers, these isolates were screened by the combined disc and disc diffusion methods to determine the ability of MBL production. Both MBL and Amp C harbored P. aeruginosa isolates were 28% (7/25). Sixty-four percent of P. aeruginosa isolates were multidrug resistant (MDR) (16/25). The sensitivity toward polymyxin, imipenem, norfloxacin, piperacillin-tazobactam and gentamicin was 99%, 91%, 88%, 82% and 78%, respectively. The resistance rate towards cefotaxime, ceftazidime, cefepime, aztreonam and meropenem was 98.6%, 86%, 71.4%, 34% and 30%, respectively. Multidrug resistance was significantly associated with MBL production in P. aeruginosa . Early detection of MBL-producing P. aeruginosa and hospital antibiotic policy prescription helps proper antimicrobial therapy and avoidance of dissemination of these multidrug resistance isolates.

Mutations in β-Lactamase AmpC Increase Resistance of Pseudomonas aeruginosa Isolates to Antipseudomonal Cephalosporins

PubMed Central

Berrazeg, M.; Jeannot, K.; Ntsogo Enguéné, Véronique Yvette; Broutin, I.; Loeffert, S.; Fournier, D.

2015-01-01

Mutation-dependent overproduction of intrinsic β-lactamase AmpC is considered the main cause of resistance of clinical strains of Pseudomonas aeruginosa to antipseudomonal penicillins and cephalosporins. Analysis of 31 AmpC-overproducing clinical isolates exhibiting a greater resistance to ceftazidime than to piperacillin-tazobactam revealed the presence of 17 mutations in the β-lactamase, combined with various polymorphic amino acid substitutions. When overexpressed in AmpC-deficient P. aeruginosa 4098, the genes coding for 20/23 of these AmpC variants were found to confer a higher (2-fold to >64-fold) resistance to ceftazidime and ceftolozane-tazobactam than did the gene from reference strain PAO1. The mutations had variable effects on the MICs of ticarcillin, piperacillin-tazobactam, aztreonam, and cefepime. Depending on their location in the AmpC structure and their impact on β-lactam MICs, they could be assigned to 4 distinct groups. Most of the mutations affecting the omega loop, the R2 domain, and the C-terminal end of the protein were shared with extended-spectrum AmpCs (ESACs) from other Gram-negative species. Interestingly, two new mutations (F121L and P154L) were predicted to enlarge the substrate binding pocket by disrupting the stacking between residues F121 and P154. We also found that the reported ESACs emerged locally in a variety of clones, some of which are epidemic and did not require hypermutability. Taken together, our results show that P. aeruginosa is able to adapt to efficacious β-lactams, including the newer cephalosporin ceftolozane, through a variety of mutations affecting its intrinsic β-lactamase, AmpC. Data suggest that the rates of ESAC-producing mutants are ≥1.5% in the clinical setting. PMID:26248364

Development and validation of a measurement procedure based on ultra-high performance liquid chromatography-tandem mass spectrometry for simultaneous measurement of β-lactam antibiotic concentration in human plasma.

PubMed

Rigo-Bonnin, Raül; Ribera, Alba; Arbiol-Roca, Ariadna; Cobo-Sacristán, Sara; Padullés, Ariadna; Murillo, Òscar; Shaw, Evelyn; Granada, Rosa; Pérez-Fernández, Xosé L; Tubau, Fe; Alía, Pedro

2017-05-01

The administration of β-lactam antibiotics in continuous infusion could let optimize the pharmacokinetic/pharmacodynamic parameters, especially in the treatment of serious bacterial infections. In this context, and also due to variability in their plasmatic concentrations, therapeutic drug monitoring (TDM) may be useful to optimize dosing and, therefore, be useful for the clinicians. We developed and validated a measurement procedure based on ultra-high performance liquid chromatography-tandem mass spectrometry for simultaneous measurement of amoxicillin, ampicillin, cloxacillin, piperacillin, cefepime, ceftazidime, cefuroxime, aztreonam and meropenem concentrations in plasma. The chromatographic separation was achieved using an Acquity®-UPLC® BEH™ (2.1×100mm id, 1.7μm) reverse-phase C 18 column, with a water/acetonitrile linear gradient containing 0.1% formic acid at a 0.4mL/min flow rate. β-Lactam antibiotics and their internal standards were detected by electrospray ionization mass spectrometry in multiple reaction monitoring mode. Chromatography run time was 7.0min and β-lactam antibiotics eluted at retention times ranging between 1.08 and 1.91min. The lower limits of quantification were between 0.50 and 1.00mg/L. Coefficients of variation and relative bias absolute values were <13.3% and 14.7%, respectively. Recovery values ranged from 55.7% to 84.8%. Evaluation of the matrix effect showed ion enhancement for all antibiotics. No interferences or carry-over were observed. Our measurement procedure could be applied to daily clinical laboratory practice to measure the concentration of β-lactam antibiotics in plasma, for instance in patients with bone and joint infections and critically ill patients. Copyright © 2017 Elsevier B.V. All rights reserved.

FIM-1, a new acquired metallo-β-lactamase from a Pseudomonas aeruginosa clinical isolate from Italy.

PubMed

Pollini, Simona; Maradei, Simona; Pecile, Patrizia; Olivo, Giuseppe; Luzzaro, Francesco; Docquier, Jean-Denis; Rossolini, Gian Maria

2013-01-01

Acquired metallo-β-lactamases (MBLs) are resistance determinants of increasing clinical importance in Gram-negative bacterial pathogens, which confer a broad-spectrum β-lactam resistance, including carbapenems. Several such enzymes have been described since the 1990s. In the present study, a novel acquired MBL, named FIM-1, was identified and characterized. The bla(FIM-1) gene was cloned from a multidrug-resistant Pseudomonas aeruginosa clinical isolate (FI-14/157) cultured from a patient with a vascular graft infection in Florence, Italy. The isolate belonged in the sequence type 235 epidemic clonal lineage. The FIM-1 enzyme is a member of subclass B1 and, among acquired MBLs, exhibited the highest similarity (ca. 40% amino acid identity) with NDM-type enzymes. In P. aeruginosa FI-14/157, the bla(FIM-1) gene was apparently inserted into the chromosome and associated with ISCR19-like elements that were likely involved in the capture and mobilization of this MBL gene. Transfer experiments of the bla(FIM-1) gene to an Escherichia coli strain or another P. aeruginosa strain by conjugation or electrotransformation were not successful. The FIM-1 protein was produced in E. coli and purified by two chromatography steps. Analysis of the kinetic parameters, carried out with the purified enzyme, revealed that FIM-1 has a broad substrate specificity, with a preference for penicillins (except the 6α-methoxy derivative temocillin) and carbapenems. Aztreonam was not hydrolyzed. Detection of this novel type of acquired MBL in a P. aeruginosa clinical isolate underscores the increasing diversity of such enzymes that can be encountered in the clinical setting.

Emergence of Pseudomonas aeruginosa with class 1 integron carrying blaVIM-2 and blaVIM-4 in the University Clinical Hospital of Bialystok (northeastern Poland).

PubMed

Michalska-Falkowska, Anna; Sacha, Paweł Tomasz; Grześ, Henryk; Hauschild, Tomasz; Wieczorek, Piotr; Ojdana, Dominika; Tryniszewska, Elżbieta Anna

2017-07-11

The effectiveness of carbapenems, considered as last-resort antimicrobials in severe infections, becomes compromised by bacterial resistance. The production of metallo-β-lactamases (MBLs) is the most significant threat to carbapenems activity among Pseudomonas aeruginosa. The aim of this study was to assess the presence and type of MBLs genes in carbapenem-resistant P. aeruginosa clinical strains, to identify the location of MBLs genes and to determine genetic relatedness between MBL-producers using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The first identified MBL-positive (with blaVIM genes) P. aeruginosa strains were isolated from patients hospitalized in the University Clinical Hospital of Bialystok in the period from September 2012 to December 2013. Variants of MBLs genes and variable integron regions were characterized by PCR and sequencing. PFGE was performed after digesting of bacterial genomes by XbaI enzyme. By MLST seven housekeeping genes were analyzed for the determination of sequence type (ST). Three strains carried the blaVIM-2 gene and one harbored the blaVIM-4 gene. The blaVIM genes resided within class 1 integrons. PCR mapping of integrons revealed the presence of four different cassette arrays. Genetic relatedness analysis by PFGE classified VIM-positive strains into four unrelated pulsotypes (A-D). MLST demonstrated the presence of four (ST 111, ST27, and ST17) different sequence type including one previously undescribed new type of ST 2342. Antimicrobial susceptibility testing showed that VIM-positive strains were resistant to carbapenems, cephalosporins, aminoglycosides, and quinolones, intermediate to aztreonam, and susceptible only to colistin. Integrons mapping, PFGE, and MLST results may point to different origin of these strains and independent introduction into hospitalized patients.

Emerging Carbapenem-Resistant Pseudomonas aeruginosa Isolates Carrying blaIMP Among Burn Patients in Isfahan, Iran.

PubMed

Radan, Mohsen; Moniri, Rezvan; Khorshidi, Ahmad; Gilasi, Hamidreza; Norouzi, Zohreh; Beigi, Fahimeh; Dasteh Goli, Yasaman

2016-09-01

Metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa is a significant pathogen in burn patients. The aim of this study was to determine the prevalence of carbapenem-resistant P. aeruginosa isolates, including those resistant to imipenemase (IMP), in a burn unit in Isfahan, Iran. One hundred and fifty P. aeruginosa isolates from burn patients were tested for antibiotic susceptibility by the disc diffusion method in accordance with CLSI guidelines. Production of MBL was identified with the EDTA disk method. DNA was purified from the MBL-positive isolates, and detection of the bla IMP gene was performed with PCR. Fifty-seven out of 150 (38%) isolates were multi-drug resistant (MDR), and 93 (62%) were extensively-drug resistant (XDR). Among all isolates, the resistance rate to ciprofloxacin, tobramycin, imipenem, meropenem, amikacin, ceftazidime, and cefepime was higher than 90%, while the resistance rates to piperacillin/tazobactam and aztreonam were 70.7% and 86%, respectively. Colistin and polymyxin B remained the most effective studied antibiotics. All of the imipenem-resistant P. aeruginosa isolates were MBL-positive, and 107 out of 144 (74.3%) of the MBL isolates were positive for the bla IMP gene. The results of this study show that the rate of P. aeruginosa -caused burn wound infections was very high, and many of the isolates were resistant to three or more classes of antimicrobials. Such extensive resistance to antimicrobial classes is important because few treatment options remain for patients with burn wound infections. bla IMP -producing P. aeruginosa isolates are a rising threat in burn-care units, and should be controlled by conducting infection-control assessments.

[Investigation of antimicrobial resistance of Klebsiella pneumoniae and Pseudomonas aeruginosa isolates from rat-like animals around a hospital in Guangzhou].

PubMed

Zhong, Xue-Shan; Ge, Jing; Chen, Shao-Wei; Xiong, Yi-Quan; Zheng, Xue-Yan; Qiu, Min; Huo, Shu-Ting; Chen, Qing

2016-05-01

To investigate antimicrobial resistance of Klebsiella pneumoniae and Pseudomonas aeruginosa isolates in fecal samples from rat-like animals. Rat-like animals were captured using cages around a hospital and the neighboring residential area between March and October, 2015. K. pneumoniae and P. aeruginosa were isolated from the fecal samples of the captured animals. Antimicrobial susceptibility test was performed according to the guidelines of Clinical and Laboratory Standards Institute (2014). A total of 329 rat-like animals were captured, including 205 Suncus murinus, 111 Rattus norvegicus, 5 Rattus flavipectus and 8 Mus musculus. The positivity rates of K. pneumoniae and P. aeruginosa were 78.4% and 34.7% in the fecal samples from the captured animals, respectively. K. pneumoniae isolates from Suncus murinus showed a high resistance to ampicillin, cephazolin, nitrofurantoin, piperacillin and cefotaxime (with resistance rates of 100%, 51.2%, 44.2%, 37.2%, and 23.3%, respectively), and K. pneumoniae isolates from Rattus spp. showed a similar drug-resistance profile. The prevalence rates of multidrug resistance and ESBLs were 40.9% and 10.7%, respectively. P. aeruginosa from both Suncus murinus and Rattus spp. exhibited the highest resistance rates to aztreonam (12.4% and 16.0%, respectively), followed by penicillins and fluoroquinolones. P. aeruginosa isolates were susceptible to cephems, aminoglycosides and carbapenems (with resistance rates below 5%). K. pneumoniae and P. aeruginosa isolated from rat-like animals showed drug-resistance profiles similar to those of the strains isolated from clinical patients, suggesting that the possible transmission of K. pneumoniae and P. aeruginosa between rat-like animals and human beings.

Occurrence of multi-antibiotic resistant Pseudomonas spp. in drinking water produced from karstic hydrosystems.

PubMed

Flores Ribeiro, Angela; Bodilis, Josselin; Alonso, Lise; Buquet, Sylvaine; Feuilloley, Marc; Dupont, Jean-Paul; Pawlak, Barbara

2014-08-15

Aquatic environments could play a role in the spread of antibiotic resistance genes by enabling antibiotic-resistant bacteria transferred through wastewater inputs to connect with autochthonous bacteria. Consequently, drinking water could be a potential pathway to humans and animals for antibiotic resistance genes. The aim of this study was to investigate occurrences of Escherichia coli and Pseudomonas spp. in drinking water produced from a karst, a vulnerable aquifer with frequent increases in water turbidity after rainfall events and run-offs. Water samples were collected throughout the system from the karstic springs to the drinking water tap during three non-turbid periods and two turbid events. E. coli densities in the springs were 10- to 1000-fold higher during the turbid events than during the non-turbid periods, indicating that, with increased turbidity, surface water had entered the karstic system and contaminated the spring water. However, no E. coli were isolated in the drinking water. In contrast, Pseudomonas spp. were isolated from the drinking water only during turbid events, while the densities in the springs were from 10- to 100-fold higher than in the non-turbid periods. All the 580 Pseudomonas spp. isolates obtained from the sampling periods were resistant (to between 1 and 10 antibiotics), with similar resistance patterns. Among all the Pseudomonas isolated throughout the drinking water production system, between 32% and 86% carried the major resistance pattern: ticarcillin, ticarcillin-clavulanic acid, cefsulodin, and/or aztreonam, and/or sulfamethoxazol-trimethoprim, and/or fosfomycin. Finally, 8 Pseudomonas spp. isolates, related to the Pseudomonas putida and Pseudomonas fluorescens species, were isolated from the drinking water. Thus, Pseudomonas could be involved in the dissemination of antibiotic resistance via drinking water during critical periods. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of VCC-1, a Novel Ambler Class A Carbapenemase from Vibrio cholerae Isolated from Imported Retail Shrimp Sold in Canada.

PubMed

Mangat, Chand S; Boyd, David; Janecko, Nicol; Martz, Sarah-Lynn; Desruisseau, Andrea; Carpenter, Michael; Reid-Smith, Richard J; Mulvey, Michael R

2016-01-11

One of the core goals of the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) is to monitor major meat commodities for antimicrobial resistance. Targeted studies with methodologies based on core surveillance protocols are used to examine other foods, e.g., seafood, for antimicrobial resistance to detect resistances of concern to public health. Here we report the discovery of a novel Ambler class A carbapenemase that was identified in a nontoxigenic strain of Vibrio cholerae (N14-02106) isolated from shrimp that was sold for human consumption in Canada. V. cholerae N14-02106 was resistant to penicillins, carbapenems, and monobactam antibiotics; however, PCR did not detect common β-lactamases. Bioinformatic analysis of the whole-genome sequence of V. cholerae N14-02106 revealed on the large chromosome a novel carbapenemase (referred to here as VCC-1, for Vibrio cholerae carbapenemase 1) with sequence similarity to class A enzymes. Two copies of blaVCC-1 separated and flanked by ISVch9 (i.e., 3 copies of ISVch9) were found in an acquired 8.5-kb region inserted into a VrgG family protein gene. Cloned blaVCC-1 conferred a β-lactam resistance profile similar to that in V. cholerae N14-02106 when it was transformed into a susceptible laboratory strain of Escherichia coli. Purified VCC-1 was found to hydrolyze penicillins, 1st-generation cephalosporins, aztreonam, and carbapenems, whereas 2nd- and 3rd-generation cephalosporins were poor substrates. Using nitrocefin as a reporter substrate, VCC-1 was moderately inhibited by clavulanic acid and tazobactam but not EDTA. In this report, we present the discovery of a novel class A carbapenemase from the food supply. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Phylogenetic grouping and pathotypic comparison of urine and fecal Escherichia coli isolates from children with urinary tract infection.

PubMed

Navidinia, Masoumeh; Peerayeh, Shahin Najar; Fallah, Fatemeh; Bakhshi, Bita; Sajadinia, Raheleh Sadat

2014-01-01

The aim of this study was to investigate the phylogenetic background and to assess hlyD (involved in the secretion of haemolysin A) and intI1 (encoding a class 1 integrase) in Escherichia coli isolates derived from urinary and fecal specimens. A total of 200 E. coli isolates was collected from patients presenting with urinary tract infection (UTI) during September 2009 to September 2010 and screened for hlyD and intI1 genes by polymerase chain reaction (PCR). Phylogenetic analysis showed that E. coli is composed of four main phylogenetic groups (A, B1, B2 and D) and that uropathogenic E. coli (UPEC) isolates mainly belong to groups B2 (54%) and D (34%) whereas group A (44%) and D (26%) are predominant among commensal E. coli isolates. In this study, hlyD was present in 26% of UPEC and 2% of commensal E. coli isolates. However, hemolytic activity was detected for 42% of UPEC and 6% of commensal E. coli isolates (p < 0.05). intI1 gene was more frequently expressed in UPEC (24%) in comparison with commensal E. coli isolates (12%). Resistance to aztreonam, co-trimoxazole and cefpodoxime were frequently found among UPEC isolates whereas commensal E. coli isolates were commonly resistant to co-trimoxazole, nalidixic acid and cefotaxime. Concluding, a considerable difference between UPEC and commensal E. coli isolates was observed regarding their phylogenetic groups, presence of class 1 integron and hlyD gene, hemolysin activity and resistance pattern. The detection of class 1 integrons and hlyD gene was higher among UPEC compared with commensal E. coli isolates. These findings may contribute for a better understanding of the factors involved in the pathogenesis of UPEC.

Phenotypic Tests for the Detection of β-Lactamase-Producing Enterobacteriaceae Isolated from Different Environments.

PubMed

de Oliveira, Daniele V; Van Der Sand, Sueli T

2016-07-01

Some bacteria from the Enterobacteriaceae family are showing a significant capability to disseminate β-lactams resistance mechanisms among them, and these same mechanisms can be carried out from the hospital environment to superficial water. The aim of this study was to evaluate different phenotypic methods for the detection β-lactamases production by enterobacteria isolated from the anthropogenic environment: hospital wastewater and from a stream that cross the city of Porto Alegre. The applied tests were the modified Hodge test (MHT) and phenotypic tests with the following inhibitors: carbapenemase-phenylboronic acid (APB), metallo-β-lactamase-EDTA, AmpC β-lactamase-cloxacillin, and the confirmatory test for extended-spectrum β-lactamase (ESBL)-clavulanic acid. For this evaluation, 131 isolates were initially subjected to antibiogram using the following antimicrobials: cefotaxime (30 µg), cefpodoxime (10 μg), ceftazidime (30 µg), ertapenem (10 μg), meropenem (10 μg), and aztreonam (30 μg). After this first screening, 62 isolates showed a profile resistance for at least one antimicrobial. These isolates were subjected to all phenotypic tests. Of those, 40 isolates were positive for at least one phenotypic test. In MHT test, one isolate was positive and five were with inconclusive results. The results achieved with the inhibitors are as follows: APB 25/40 positive strains; EDTA 8/40 positive strains; and with CLOXA 2/40 positive strains. ESBL production was observed for 34/40 strains. This assessment shows a high level of bacteria which can produce enzymes that inactivate β-lactams present in the different environment like the stream waters and from the hospital settings.

[Urinary tract infection in pregnancy and menopause].

PubMed

Broseta Rico, Enrique; Jiménez Cruz, Juan Fernando

2002-11-01

To review the topic of urinary tract infections (UTI) during pregnancy and menopause. UTI during pregnancy and menopause have great relevance in the field of urologic infections; during pregnancy because of the particularities involved in its diagnosis and treatment and potential consequences to the fetus and mother; menopausal UTI because this group of women is numerous and represents a growing section of the general population pyramid, due to the aging of population in developed countries associated with longer life expectancies and grater demand for quality of life. We performed a bibliographic review combined with our personal experience. During pregnancy there are several functional and anatomical changes that condition not only a higher risk of UTI, but also an additional treatment difficulty due to antimicrobial pharmacokinetics alterations and potential damage to the fetus. Despite efforts to find an easy, fast and reliable test for bacteriuria detection, urine culture continues to be the first diagnostic test for its detection and follow up during pregnancy. Penicillin derivates and cephalosporins continue to be the first choice because their lack of adverse effects on either fetus or mother. Alternative options like phosphomicin and aztreonam although they show low toxicity there is need for more studies supporting their suitability for the treatment of pregnancy UTIs. Menopausal female UTI have their different features from those in younger women. Hormonal alterations derived from gonadal atrophy associate functional changes in the vaginal ecosystem, making it prone to enterobacteriaceae colonization as a first step up to the urinary tract. This associated with genitourinary tract anatomical alterations inherent t aging make UTI extraordinary prevalent in this growing segment of population. Treatment lines focus on hormonal alteration correction and proper antimicrobial prophylaxis and vaccines in a close future. UTIs during pregnancy and menopause have differential features that require different diagnostic and treatment approaches.

Plasmid-Mediated Resistance to Expanded-Spectrum Cephalosporins among Enterobacter aerogenes Strains

PubMed Central

Pitout, Johann D. D.; Thomson, Kenneth S.; Hanson, Nancy D.; Ehrhardt, Anton F.; Coudron, Philip; Sanders, Christine C.

1998-01-01

Resistance to expanded-spectrum cephalosporins commonly develops in Enterobacter aerogenes during therapy due to selection of mutants producing high levels of the chromosomal Bush group 1 β-lactamase. Recently, resistant strains producing plasmid-mediated extended-spectrum β-lactamases (ESBLs) have been isolated as well. A study was designed to investigate ESBL production among 31 clinical isolates of E. aerogenes from Richmond, Va., with decreased susceptibility to expanded-spectrum cephalosporins and a positive double-disk potentiation test. Antibiotic susceptibility was determined by standard disk diffusion and agar dilution procedures. β-Lactamases were investigated by an isoelectric focusing overlay technique which simultaneously determined isoelectric points (pIs) and substrate or inhibitor profiles. Decreased susceptibility to cefotaxime, ceftazidime, and aztreonam (MIC range, 1 to 64 μg/ml) was detected and associated with resistance to gentamicin and trimethoprim-sulfamethoxazole. All strains produced an inducible Bush group 1 β-lactamase (pI 8.3). Twenty-nine of the 31 isolates also produced an enzyme similar to SHV-4 (pI 7.8), while 1 isolate each produced an enzyme similar to SHV-3 (pI 6.9) and to SHV-5 (pI 8.2). The three different SHV-derived ESBLs were transferred by transconjugation to Escherichia coli C600N and amplified by PCR. Plasmid profiles of the clinical isolates showed a variety of different large plasmids. Because of the linkage of resistance to aminoglycosides and trimethoprim-sulfamethoxazole with ESBL production, it is possible that the usage of these drugs was responsible for selecting plasmid-mediated resistance to extended-spectrum cephalosporins in E. aerogenes. Furthermore, it is important that strains such as these be recognized, because they can be responsible for institutional spread of resistance genes. PMID:9517938

A preliminary quality of life questionnaire-bronchiectasis: a patient-reported outcome measure for bronchiectasis.

PubMed

Quittner, Alexandra L; Marciel, Kristen K; Salathe, Matthias A; O'Donnell, Anne E; Gotfried, Mark H; Ilowite, Jonathan S; Metersky, Mark L; Flume, Patrick A; Lewis, Sandra A; McKevitt, Matthew; Montgomery, A Bruce; O'Riordan, Thomas G; Barker, Alan F

2014-08-01

The Quality of Life Questionnaire-Bronchiectasis (QOL-B) is the first disease-specific, patient-reported outcome measure for patients with bronchiectasis. Content validity, cognitive testing, responsivity to open-label treatment, and psychometric analyses are presented. Reviews of literature, existing measures, and physician input were used to generate the initial QOL-B. Modifications following preliminary cognitive testing (N = 35 patients with bronchiectasis) generated version (V) 1.0. An open-ended patient interview study (N = 28) provided additional information and was content analyzed to derive saturation matrices, which summarized all disease-related topics mentioned by each participant. This resulted in QOL-B V2.0. Psychometric analyses were carried out using results from an open-label phase 2 trial, in which 89 patients were enrolled and treated with aztreonam for inhalation solution. Responsivity to open-label treatment was observed. Additional analyses generated QOL-B V3.0, with 37 items on eight scales: respiratory symptoms; physical, role, emotional, and social functioning; vitality; health perceptions; and treatment burden. For each scale, scores are standardized on a 0-to-100-point scale; higher scores indicate better health-related quality of life. No total score is calculated. A final cognitive testing study (N = 40) resulted in a minor change to one social functioning scale item (QOL-B V3.1). Content validity, cognitive testing, responsivity to open-label treatment, and initial psychometric analyses supported QOL-B items and structure. This interim QOL-B is a promising tool for evaluating the efficacy of new therapies for patients with bronchiectasis and for measuring symptoms, functioning, and quality of life in these patients on a routine basis. A final psychometric validation study is needed and is forthcoming. ClinicalTrials.gov; No.: NCT00805025; URL: www.clinicaltrials.gov.

Structural basis for effectiveness of siderophore-conjugated monocarbams against clinically relevant strains of Pseudomonas aeruginosa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Seungil; Zaniewski, Richard P.; Marr, Eric S.

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that causes nosocomial infections for which there are limited treatment options. Penicillin-binding protein PBP3, a key therapeutic target, is an essential enzyme responsible for the final steps of peptidoglycan synthesis and is covalently inactivated by {beta}-lactam antibiotics. Here we disclose the first high resolution cocrystal structures of the P. aeruginosa PBP3 with both novel and marketed {beta}-lactams. These structures reveal a conformational rearrangement of Tyr532 and Phe533 and a ligand-induced conformational change of Tyr409 and Arg489. The well-known affinity of the monobactam aztreonam for P. aeruginosa PBP3 is due to a distinct hydrophobicmore » aromatic wall composed of Tyr503, Tyr532, and Phe533 interacting with the gem-dimethyl group. The structure of MC-1, a new siderophore-conjugated monocarbam complexed with PBP3 provides molecular insights for lead optimization. Importantly, we have identified a novel conformation that is distinct to the high-molecular-weight class B PBP subfamily, which is identifiable by common features such as a hydrophobic aromatic wall formed by Tyr503, Tyr532, and Phe533 and the structural flexibility of Tyr409 flanked by two glycine residues. This is also the first example of a siderophore-conjugated triazolone-linked monocarbam complexed with any PBP. Energetic analysis of tightly and loosely held computed hydration sites indicates protein desolvation effects contribute significantly to PBP3 binding, and analysis of hydration site energies allows rank ordering of the second-order acylation rate constants. Taken together, these structural, biochemical, and computational studies provide a molecular basis for recognition of P. aeruginosa PBP3 and open avenues for future design of inhibitors of this class of PBPs.« less

Characterization of VCC-1, a Novel Ambler Class A Carbapenemase from Vibrio cholerae Isolated from Imported Retail Shrimp Sold in Canada

PubMed Central

Mangat, Chand S.; Boyd, David; Janecko, Nicol; Martz, Sarah-Lynn; Desruisseau, Andrea; Carpenter, Michael; Reid-Smith, Richard J.

2016-01-01

One of the core goals of the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) is to monitor major meat commodities for antimicrobial resistance. Targeted studies with methodologies based on core surveillance protocols are used to examine other foods, e.g., seafood, for antimicrobial resistance to detect resistances of concern to public health. Here we report the discovery of a novel Ambler class A carbapenemase that was identified in a nontoxigenic strain of Vibrio cholerae (N14-02106) isolated from shrimp that was sold for human consumption in Canada. V. cholerae N14-02106 was resistant to penicillins, carbapenems, and monobactam antibiotics; however, PCR did not detect common β-lactamases. Bioinformatic analysis of the whole-genome sequence of V. cholerae N14-02106 revealed on the large chromosome a novel carbapenemase (referred to here as VCC-1, for Vibrio cholerae carbapenemase 1) with sequence similarity to class A enzymes. Two copies of blaVCC-1 separated and flanked by ISVch9 (i.e., 3 copies of ISVch9) were found in an acquired 8.5-kb region inserted into a VrgG family protein gene. Cloned blaVCC-1 conferred a β-lactam resistance profile similar to that in V. cholerae N14-02106 when it was transformed into a susceptible laboratory strain of Escherichia coli. Purified VCC-1 was found to hydrolyze penicillins, 1st-generation cephalosporins, aztreonam, and carbapenems, whereas 2nd- and 3rd-generation cephalosporins were poor substrates. Using nitrocefin as a reporter substrate, VCC-1 was moderately inhibited by clavulanic acid and tazobactam but not EDTA. In this report, we present the discovery of a novel class A carbapenemase from the food supply. PMID:26824956

Effect of various antibiotics on modulation of intestinal microbiota and bile acid profile in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Youcai; Limaye, Pallavi B.; Renaud, Helen J.

Antibiotic treatments have been used to modulate intestinal bacteria and investigate the role of intestinal bacteria on bile acid (BA) homeostasis. However, knowledge on which intestinal bacteria and bile acids are modified by antibiotics is limited. In the present study, mice were administered various antibiotics, 47 of the most abundant bacterial species in intestine, as well as individual BAs in plasma, liver, and intestine were quantified. Compared to the two antibiotic combinations (vancomycin + imipenem and cephalothin + neomycin), the three single antibiotics (metronidazole, ciprofloxacin and aztreonam) have less effect on intestinal bacterial profiles, and thus on host BA profilesmore » and mRNA expression of genes that are important for BA homeostasis. The two antibiotic combinations decreased the ratio of Firmicutes to Bacteroidetes in intestine, as well as most secondary BAs in serum, liver and intestine. Additionally, the two antibiotic combinations significantly increased mRNA of the hepatic BA uptake transporters (Ntcp and Oatp1b2) and canalicular BA efflux transporters (Bsep and Mrp2), but decreased mRNA of the hepatic BA synthetic enzyme Cyp8b1, suggesting an elevated enterohepatic circulation of BAs. Interestingly, the two antibiotic combinations tended to have opposite effect on the mRNAs of most intestinal genes, which tended to be inhibited by vancomycin + imipenem but stimulated by cephalothin + neomycin. To conclude, the present study clearly shows that various antibiotics have distinct effects on modulating intestinal bacteria and host BA metabolism. - Highlights: • Various antibiotics have different effects on intestinal bacteria. • Antibiotics alter bile acid composition in mouse liver and intestine. • Antibiotics influence genes involved in bile acid homeostasis. • Clostridia appear to be important for secondary bile acid formation.« less

Antimicrobial susceptibilities and bacteriological characteristics of bovine Pseudomonas aeruginosa and Serratia marcescens isolates from mastitis.

PubMed

Ohnishi, Mamoru; Sawada, Takuo; Hirose, Kazuhiko; Sato, Reiichiro; Hayashimoto, Mizuki; Hata, Eiji; Yonezawa, Chizuko; Kato, Hajime

2011-12-29

The presence of metallo-β-lactamase (MBL)-producing and multidrug-resistant Pseudomonas aeruginosa (MDRP) strains among bovine isolates of Gram-negative bacilli, and O-serotypes of bovine Serratia marcescens and P. aeruginosa isolates have been reported rarely. The aims of this study were to (1) elucidate antimicrobial susceptibilities and O-serotypes of P. aeruginosa and S. marcescens isolates from bovine mastitis and the presence of MBL-producers and MDRP strains among them and (2) evaluate their relationships to human isolates. We investigated the MICs of 24 antimicrobials and O-serotypes for 116 P. aeruginosa and 55 S. marcescens isolates in Japan, primarily in 2006. A total of 171 isolates exhibited high antimicrobial susceptibilities with the exception of a partial drug. P. aeruginosa isolates exhibited high susceptibilities of ≥ 95.7% to ciprofloxacin, imipenem, meropenem, piperacillin, ceftazidime, cefepime, cefoperazone/sulbactam, amikacin, tobramycin, and gentamicin; however, they exhibited a susceptibility of only 69.8% to aztreonam. They exhibited substantial resistances to ceftriaxone, enrofloxacin, cefotaxime, and moxalactam. S. marcescens isolates exhibited high susceptibilities of ≥ 90.9% to kanamycin, ceftiofur, sulfamethoxazole-trimethoprim, and the 15 aforementioned drugs, but exhibited resistance to minocycline. Neither MBL-producers nor MDRP strains were detected among the 171 strains. The dominant serotypes of P. aeruginosa isolates were OG, OA, OB, OI, OF, OE, and OK; those of S. marcescens isolates were O6 and O5. Every S. marcescens isolate was pigmented. These findings suggest that bovine P. aeruginosa and S. marcescens isolates differ from human isolates from both antibiogram and phenotypic perspectives, and could help to evaluate differences in bacteriological characteristics between bovine and human isolates. Copyright © 2011 Elsevier B.V. All rights reserved.

Regional variation in the prevalence of extended-spectrum beta-lactamase-producing clinical isolates in the Asia-Pacific region (SENTRY 1998-2002).

PubMed

Hirakata, Yoichi; Matsuda, Junichi; Miyazaki, Yoshitsugu; Kamihira, Shimeru; Kawakami, Sayoko; Miyazawa, Yukihisa; Ono, Yasuo; Nakazaki, Nobuhiko; Hirata, Yasuyoshi; Inoue, Matsuhisa; Turnidge, John D; Bell, Jan M; Jones, Ronald N; Kohno, Shigeru

2005-08-01

We examined the prevalence of extended-spectrum beta-lactamase (ESBL)-producing strains of Klebsiella pneumoniae, Klebsiella oxytoca, Escherichia coli, Proteus mirabilis, Citrobacter koseri, and Salmonella spp. that were isolated as part of the SENTRY Asia-Pacific Surveillance Program between 1998 and 2002. During the study period, a total of 6,388 strains were gathered from 17 medical centers in 7 countries and examined for ESBL production and hyperproduction of K. oxytoca chromosomal K1 beta-lactamase enzyme. High rates of confirmed ESBL-producing isolates were found in K. pneumoniae strains from Singapore (35.6%), followed by those from mainland China (30.7%), South Africa (28.1%), and the Philippines (21.9%), whereas the rates were less than 10% in Japan and Australia. ESBL-producing E. coli strains were also prominent in mainland China (24.5%), Hong Kong (14.3%), and Singapore (11.3%). ESBL-producing K. oxytoca were common in the Philippines (38.5%), Singapore (33.3%), and China (30.0%). Hyperproduction of K. oxytoca chromosomal K1 beta-lactamase enzyme was common in Australia and Japan. P. mirabilis strains from Singapore produced ESBL (17.9%) despite the low prevalence (0-8.1%) in other countries. Few ESBL-producing C. koseri and Salmonella spp. strains were found in Japan, Singapore, Taiwan, and South Africa. Although there was variation among countries in substrate preference, ceftazidime was more likely to detect presumptive ESBL phenotype in K. pneumoniae and aztreonam more likely in E. coli, whereas ceftriaxone was the best substrate for the confirmation of ESBL production. ESBL-producing strains showed high levels of co-resistance to aminoglycosides, tetracycline, trimethoprim-sulfamethoxazole, and ciprofloxacin. Imipenem retained activity against all ESBL-producing strains. Organisms expressing ESBLs are widely distributed in the Asia-Pacific region, although prevalence rates vary significantly.

beta-Lactam resistance in salmonella strains isolated from retail meats in the United States by the National Antimicrobial Resistance Monitoring System between 2002 and 2006.

PubMed

Zhao, S; Blickenstaff, K; Glenn, A; Ayers, S L; Friedman, S L; Abbott, J W; McDermott, P F

2009-12-01

Ampicillin-resistant (Amp(r)) Salmonella enterica isolates (n = 344) representing 32 serotypes isolated from retail meats from 2002 to 2006 were tested for susceptibility to 21 other antimicrobial agents and screened for the presence of five beta-lactamase gene families (bla(CMY), bla(TEM), bla(SHV), bla(OXA), and bla(CTX-M)) and class 1 integrons. Among the Amp(r) isolates, 66.9% were resistant to five or more antimicrobials and 4.9% were resistant to 10 or more antimicrobials. Coresistance to other beta-lactams was noted for amoxicillin-clavulanic acid (55.5%), ceftiofur (50%), cefoxitin (50%), and ceftazidime (24.7%), whereas less than 5% of isolates were resistant to piperacillin-tazobactam (4.9%), cefotaxime (3.5%), ceftriaxone (2%), and aztreonam (1.2%). All isolates were susceptible to cefepime, imipenem, and cefquinome. No Salmonella producing extended-spectrum beta-lactamases was found in this study. Approximately 7% of the isolates displayed a typical multidrug-resistant (MDR)-AmpC phenotype, with resistance to ampicillin, chloramphenicol, streptomycin, sulfonamide, tetracycline, plus resistance to amoxicillin-clavulanic acid, cefoxitin, and ceftiofur and with decreased susceptibility to ceftriaxone (MIC > or = 4 microg/ml). Pulsed-field gel electrophoresis results showed that several MDR clones were geographically dispersed in different types of meats throughout the five sampling years. Additionally, 50% of the isolates contained bla(CMY), 47% carried bla(TEM-1), and 2.6% carried both genes. Only 15% of the isolates harbored class I integrons carrying various combinations of aadA, aadB, and dfrA gene cassettes. The bla(CMY), bla(TEM), and class 1 integrons were transferable through conjugation and/or transformation. Our findings indicate that a varied spectrum of coresistance traits is present in Amp(r) Salmonella strains in the meat supply of the United States, with a continued predominance of bla(CMY) and bla(TEM) genes in beta-lactam-resistant isolates.

[Effect of inoculum size on sensitivity and specificity of the double-disk synergy test for the detection of wide-spectrum beta-lactamases].

PubMed

Bedenić, B; Boras, A

2001-01-01

The plasmid-mediated extended-spectrum beta-lactamases (ESBL) confer resistance to oxymino-cephalosporins, such as cefotaxime, ceftazidime, and ceftriaxone and to monobactams such as aztreonam. It is well known fact that ESBL producing bacteria exhibit a pronounced inoculum effect against broad spectrum cephalosporins like ceftazidime, cefotaxime, ceftriaxone and cefoperazone. The aim of this investigation was to determine the effect of inoculum size on the sensitivity and specificity of double-disk synergy test (DDST) which is the test most frequently used for detection of ESBLs, in comparison with other two methods (determination of ceftazidime MIC with and without clavulanate and inhibitor potentiated disk-diffusion test) which are seldom used in clinical laboratories. The experiments were performed on a set of K. pneumoniae strains with previously characterized beta-lactamases which comprise: 10 SHV-5 beta-lactamase producing K. pneumoniae, 20 SHV-2 + 1 SHV 2a beta-lactamase producing K. pneumoniae, 7 SHV-12 beta-lactamase producing K. pneumoniae, 39 putative SHV ESBL producing K. pneumoniae and 26 K. pneumoniae isolates highly susceptible to ceftazidime according to Kirby-Bauer disk-diffusion method and thus considered to be ESBL negative. According to the results of this investigation, increase in inoculum size affected more significantly the sensitivity of DDST than of other two methods. The sensitivity of the DDST was lower when a higher inoculum size of 10(8) CFU/ml was applied, in distinction from other two methods (MIC determination and inhibitor potentiated disk-diffusion test) which retained high sensitivity regardless of the density of bacterial suspension. On the other hand, DDST displayed higher specificity compared to other two methods regardless of the inoculum size. This investigation found that DDST is a reliable method but it is important to standardize the inoculum size.

Characteristics of carbapenem-resistant Pseudomonas aeruginosa strains in patients with ventilator-associated pneumonia in intensive care units.

PubMed

Vitkauskienė, Astra; Skrodenienė, Erika; Dambrauskienė, Asta; Bakšytė, Giedrė; Macas, Andrius; Sakalauskas, Raimundas

2011-01-01

The aim of this study was to determine the characteristics of carbapenem-resistant Pseudomonas aeruginosa (P. aeruginosa) strains and 5-year changes in resistance in a tertiary university hospital. The study included 90 and 101 randomly selected P. aeruginosa strains serotyped in 2003 and 2008, respectively. The standardized disk diffusion test and E-test were used to determine resistance to antibiotics. P. aeruginosa strains were considered to have high-level resistance if a minimum inhibitory concentration (MIC) for imipenem or meropenem was >32 µg/mL. To identify serogroups, sera containing specific antibodies against O group antigens of P. aeruginosa were used. P. aeruginosa isolates resistant to imipenem or/and meropenem were screened for metallo-β-lactamase (MBL) production by using the MBL E-test. Comparison of the changes in resistance of P. aeruginosa strains to carbapenems within the 5-year period revealed that the level of resistance to imipenem increased. In 2003, 53.3% of P. aeruginosa strains were found to be highly resistant to imipenem, while in 2008, this percentage increased to 87.8% (P=0.01). The prevalence of MBL-producing strains increased from 15.8% in 2003 to 61.9% in 2008 (P<0.001). In 2003 and 2008, carbapenem-resistant P. aeruginosa strains were more often resistant to ciprofloxacin and gentamicin than carbapenem-sensitive strains. In 2008, carbapenem-resistant strains additionally were more often resistant to ceftazidime, cefepime, aztreonam, piperacillin, and amikacin than carbapenem-sensitive strains. MBL-producing P. aeruginosa strains belonged more often to the O:11 serogroup than MBL-non-producing strains (51.7% vs. 34.3%, P<0.05). A greater percentage of non-MBL-producing strains had low MICs against ciprofloxacin and amikacin as compared with MBL-producing strains. The results of our study emphasize the need to restrict the spread of O:11 serogroup P. aeruginosa strains and usage of carbapenems to treat infections with P. aeruginosa in the intensive care units of our hospital.

Multiyear, Multinational Survey of the Incidence and Global Distribution of Metallo-β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa.

PubMed

Kazmierczak, Krystyna M; Rabine, Sharon; Hackel, Meredith; McLaughlin, Robert E; Biedenbach, Douglas J; Bouchillon, Samuel K; Sahm, Daniel F; Bradford, Patricia A

2016-02-01

Metallo-β-lactamases (MBLs) hydrolyze all classes of β-lactams except monobactams and are not inhibited by classic serine β-lactamase inhibitors. Gram-negative pathogens isolated from patient infections were collected from 202 medical centers in 40 countries as part of a global surveillance study from 2012 to 2014. Carbapenem-nonsusceptible Enterobacteriaceae and Pseudomonas aeruginosa were characterized for bla genes encoding VIM, IMP, NDM, SPM, and GIM variants using PCR and sequencing. A total of 471 MBL-positive isolates included the following species (numbers of isolates are in parentheses): P. aeruginosa (308), Klebsiella spp. (85), Enterobacter spp. (39), Proteeae (16), Citrobacter freundii (12), Escherichia coli (6), and Serratia marcescens (5) and were submitted by sites from 34 countries. Of these, 69.6% were collected in 9 countries (numbers of isolates are in parentheses): Russia (72), Greece (61), Philippines (54), Venezuela (29), and Kuwait, Nigeria, Romania, South Africa, and Thailand (20 to 25 isolates each). Thirty-two different MBL variants were detected (14 VIM, 14 IMP, and 4 NDM enzymes). Seven novel MBL variants were encountered in the study, each differing from a previously reported variant by one amino acid substitution: VIM-42 (VIM-1 [V223I]), VIM-43 (VIM-4 [A24V]), VIM-44 (VIM-2 [K257N]), VIM-45 (VIM-2 [T35I]), IMP-48 (IMP-14 [I69T]), IMP-49 (IMP-18 [V49F]), and NDM-16 (NDM-1 [R264H]). The in vitro activities of all tested antibiotics against MBL-positive Enterobacteriaceae were significantly reduced with the exception of that of aztreonam-avibactam (MIC90, 0.5 to 1 μg/ml), whereas colistin was the most effective agent against MBL-positive P. aeruginosa isolates (>97% susceptible). Although the global percentage of isolates encoding MBLs remains relatively low, their detection in 12 species, 34 countries, and all regions participating in this surveillance study is concerning. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

RESULTS OF MONITORING METALLO-BETA-LACTAMASE-PRODUCING STRAINS OF PSEUDOMONAS AERUGINOSA IN A MULTI-PROFILE HOSPITAL.

PubMed

Shamaeva, S K; Portnyagina, U S; Edelstein, M V; Kuzmina, A A; Maloguloval, S; Varfolomeeva, N A

2015-01-01

The authors present the results of long-term monitoring of metallo-beta-lactamase (MBL) producing strains of Pseudomonas aeruginosa in the Republican Hospital No 2 of Yakutsk, Russian Federation. Hospitals across Russia, as well as the rest of the world, face a rapid appearance and a virtually unchecked spread of multiresistant and panresistant nosocomial pathogens. Especially prevalent are multidrug-resistant isolates of P. aeruginosa, most often found among the patients of intensive care and intensive therapy units, as well as surgery departments. The aim of this study is to investigate the prevalence of metallo-beta-lactamase-producing strains of P. aeruginosa in a multi-profile hospital. 2,135 isolates of P. aeruginosa were studied, collected during a time span of seven years (2008-2014) from clinical specimens of hospitalised patients in acute surgery, purulent surgery, neurosurgery, otolaryngology, coloproctology departments, intensive care and intensive therapy, burn units, as well as intensive care unit for patients with acute cerebrovascular accidents and coronary care unit. Strains were identified and re-identified using established methods, NEFERMtest 24 (MICROLATEST) biochemical microtest and API (bioMerieux) test systems were used. For all carbapenem-resistant strains a phenotype screening for MBL was performed using the double-disks method with EDTA. In order to identify VIM-type and IMP-type MBL genes a real-time multiplex polymerase chain reaction was used. Among the investigated strains the largest number of P. aeruginosa - 35.6% (761 isolates) was found in patients at intensive care and intensive therapy units. Clonal expansion of extensively drug-resistant strain P. aeruginosa ST235 (VIM-2) was determined, the resistance mechanism of which is connected to MBL. Sensitivity determination of MBL-producing isolates of P. aeruginosa has shown that isolated strains have a high level of resistance (100%) to all tested antibacterial agents: piperacillin, piperacillin-tazobactam, ceftazidime, cefepime, cefoperazone-sulbactam, aztreonam, imipenem, meropenem, doripenem, gentamicin, netilmicin, amikacin, ciprofloxacin, levofloxacin, fosfomicin.

Multiyear, Multinational Survey of the Incidence and Global Distribution of Metallo-β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

PubMed Central

Rabine, Sharon; Hackel, Meredith; McLaughlin, Robert E.; Biedenbach, Douglas J.; Bouchillon, Samuel K.; Sahm, Daniel F.; Bradford, Patricia A.

2015-01-01

Metallo-β-lactamases (MBLs) hydrolyze all classes of β-lactams except monobactams and are not inhibited by classic serine β-lactamase inhibitors. Gram-negative pathogens isolated from patient infections were collected from 202 medical centers in 40 countries as part of a global surveillance study from 2012 to 2014. Carbapenem-nonsusceptible Enterobacteriaceae and Pseudomonas aeruginosa were characterized for bla genes encoding VIM, IMP, NDM, SPM, and GIM variants using PCR and sequencing. A total of 471 MBL-positive isolates included the following species (numbers of isolates are in parentheses): P. aeruginosa (308), Klebsiella spp. (85), Enterobacter spp. (39), Proteeae (16), Citrobacter freundii (12), Escherichia coli (6), and Serratia marcescens (5) and were submitted by sites from 34 countries. Of these, 69.6% were collected in 9 countries (numbers of isolates are in parentheses): Russia (72), Greece (61), Philippines (54), Venezuela (29), and Kuwait, Nigeria, Romania, South Africa, and Thailand (20 to 25 isolates each). Thirty-two different MBL variants were detected (14 VIM, 14 IMP, and 4 NDM enzymes). Seven novel MBL variants were encountered in the study, each differing from a previously reported variant by one amino acid substitution: VIM-42 (VIM-1 [V223I]), VIM-43 (VIM-4 [A24V]), VIM-44 (VIM-2 [K257N]), VIM-45 (VIM-2 [T35I]), IMP-48 (IMP-14 [I69T]), IMP-49 (IMP-18 [V49F]), and NDM-16 (NDM-1 [R264H]). The in vitro activities of all tested antibiotics against MBL-positive Enterobacteriaceae were significantly reduced with the exception of that of aztreonam-avibactam (MIC90, 0.5 to 1 μg/ml), whereas colistin was the most effective agent against MBL-positive P. aeruginosa isolates (>97% susceptible). Although the global percentage of isolates encoding MBLs remains relatively low, their detection in 12 species, 34 countries, and all regions participating in this surveillance study is concerning. PMID:26643349

Molecular and Phenotypic Analysis of Hemolytic Aeromonas Strains Isolated from Food in Egypt Revealed Clinically Important Multidrug Resistance and Virulence Profiles.

PubMed

Hammad, Ahmed M; Moustafa, Alaa-Eldin H; Mansour, Maha M; Fahmy, Bashier M; Hamada, Mohamed G; Shimamoto, Toshi; Shimamoto, Tadashi

2018-06-01

The aim of this study was to determine the public health significance of hemolytic Aeromonas species isolated from 213 food samples in Egypt, based on their virulence and antimicrobial-resistance potential. We recovered 63 strains, isolated from fish, raw milk, karish cheeses, and ras cheese in 29 (31.18%) of 93, 10 (25.00%) of 40, 13 (32.50%) of 40, and 11 (27.50%) of 40 samples, respectively. The most prevalent virulence gene was alt (50.79%), followed by aerA (34.92%), asa1 (39.68%), ahh1 (20.63%), act (11.11%), and ast (3.17%). Thirteen strains screened in this study carried no hemolysin gene, but only the alt gene, and another eight hemolytic strains screened, carried no virulence gene. The virulence signatures " ahh1+ aerA" and " alt+ act," in which the genes interact synergistically to induce severe diarrhea, were detected in two and four strains, respectively. Most showed resistance to third-generation cephalosporins, aztreonam, and imipenem, which indicates the complexity of the β-lactamase production in our hemolytic Aeromonas strains. Fourteen (22.22%) of 63 strains carried one or more antimicrobial-resistance markers, including the bla CTX-M , bla TEM , tet(A), tet(E), and intI1 genes, which were detected in 6.34, 3.17, 3.17, 4.76, and 14.28% of isolates, respectively. In conclusion, the majority of hemolytic Aeromonas strains isolated from the intestinal contents of healthy fish and naturally contaminated milk and cheeses were not commensal but had developed multidrug-resistance and virulence profiles, indicating an emerging potential health risk. Importantly, screening for certain hemolysin genes may not be reliable in predicting the pathogenic potential of Aeromonas species and, thereby, the safety of analyzed foods. Our findings indicate that specific criteria are required for the phenotypic and molecular analysis of Aeromonas species in food items, particularly those eaten without further treatment, to ensure their safety.

Distribution of Ambler class A, B and D β-lactamases among Pseudomonas aeruginosa isolates.

PubMed

Tawfik, Abdulkader F; Shibl, Atef M; Aljohi, Mohamed A; Altammami, Musaad A; Al-Agamy, Mohamed H

2012-09-01

We determined the prevalence rate of classes A, B and D β-lactamases among extended-spectrum cephalosporin (ESC)-non-susceptible Pseudomonas aeruginosa clinical isolates from burned patients. Disc susceptibility testing was performed on 156 P. aeruginosa isolates collected during 2010 at Prince Salman Hospital in Riyadh, Saudi Arabia. Phenotypic screening of ESBLs and MBLs in the isolates resistant to ceftazidime (MIC>8 mg/L) was carried out. Genes encoding ESBLs and MBL were sought by PCR in ESBL- and MBL-producing isolates. The resistance rate to ceftazidime was 22.43%. The resistance rates for ESC-non-susceptible P. aeruginosa isolates to piperacillin, piperacillin/tazobactam, cefepime, aztreonam, imipenem, amikacin, gentamicin and ciprofloxacin were 100%, 71.14%, 88.57%, 48.57%, 70.0%, 82.5%, 87.5%, and 90.0% respectively. No resistance was detected to polymyxine B. The prevalence of ESBL and MBL in ESC-non-susceptible P. aeruginosa was 69.44% and 42.85%, respectively. The prevalence of structural genes for VEB-1, OXA-10 and GES ESBLs in P. aeruginosa was 68%, 56% and 20%, respectively. VIM gene was detected in 15 (100%) of MBL-producing isolates. OXA-10 like gene was concomitant with VEB, GES and/or VIM. Eight isolates harbored OXA-10 with VEB (imipenem MIC 6-8 mg/L), while five isolates harbored OXA-10 with VIM (imipenem MIC ≥ 32 mg/L) and one isolate contained OXA-10, VEB and GES (imipenem MIC 8 mg/L). PER was not detected in this study. VEB-1 and OXA-10 are the predominant ESBL genes and bla(VIM) is the dominate MBL gene in ESC-non-sensitive P. aeruginosa isolates in Saudi Arabia. VEB, OXA-10 and GES ESBLs have not been reported previously in Saudi Arabia and GES has not been reported previously in Middle East and North Africa. Copyright © 2012 Elsevier Ltd and ISBI. All rights reserved.

Antimicrobial susceptibility and genetic characterization of Escherichia coli recovered from frozen game meat.

PubMed

Mateus-Vargas, Rafael H; Atanassova, Viktoria; Reich, Felix; Klein, Günter

2017-05-01

The increasing number of antimicrobial resistant Enterobacteriaceae both in veterinary and human medicine, the dissemination of these bacteria in several environments and their possible repercussions on human health is causing concern. Game meat is usually seen as free of antimicrobial resistant bacteria. The objective of this study was to evaluate the current antimicrobial susceptibility status in generic Escherichia coli isolated from packed frozen game meat from a game handling establishment in Germany. A total of 229 E. coli isolates were obtained from cuts of red deer, roe deer and wild boar. The susceptibility to 12 antimicrobial agents was evaluated by a broth microdilution method according to ISO 20776-1:2006. Minimal Inhibitory Concentration (MIC) values were compared to breakpoints and cut-off values published by the EUCAST. Isolates showing MICs above the reference values were further studied for associated resistance determinants and phylogrouping by PCR. Overall, 16 E. coli isolates (7.0%) showed resistance (microbiological or clinical) to at least one antimicrobial agent tested. Clinical resistance was recorded to ampicillin (5/229) and chloramphenicol (4/229), whereas the MIC of 9 isolates exceeded the epidemiological cut-off value for doxycycline. One of the ampicillin-resistant isolates showed resistance to the β-lactam antibiotic derivatives tested, cephalosporines and aztreonam. Three of 9 non-wild-type isolates for doxycycline were positive for tet (B) genes. The ß-lactam-resistant isolate was found to harbour bla CTX-M-1 gene. These data show a low prevalence of resistant E. coli in packed game meat compared to studies on conventional meat. Although isolates obtained in this study may also be originating from the processing environment and not necessarily from animals, based on our results, it is important to monitor the development of antimicrobial resistance in game animals and products in order to identify future threats for the consumers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection of qnrVC6, within a new genetic context, in a NDM-1-producing Citrobacter freundii clinical isolate from Uruguay.

PubMed

Bado, Inés; Ezdra, Romina Papa; Cordeiro, Nicolás; Outeda, Matilde; Caiata, Leticia; García-Fulgueiras, Virginia; Seija, Verónica; Vignoli, Rafael

2018-03-08

The objective of the present study was to characterise the mechanisms underlying quinolone and oxyimino-cephalosporin resistance in a Citrobacter freundii clinical isolate obtained from the ICU in Uruguay's University Hospital. Citrobacter freundii strain CF638 was isolated from a urine culture. Identification and susceptibility testing were performed using the VITEK ® 2 system, and MIC determination and disc diffusion assay, respectively. Resistance genes and mobile genetic elements were identified, by PCR and sequencing. Plasmid transfer was assessed by conjugation; plasmid, size was estimated by treatment with S1 and PFGE. Plasmid incompatibility, group and toxin-antitoxin systems were sought by PCR. Strain CF638 showed a multi-drug resistant profile, including, resistance to carbapenemes and quinolones. Transconjugant TcCF638, harbouring a ∼200 kb IncA/C plasmid, also showed resistance to all β-lactams, (except for aztreonam), and diminished susceptibility to ciprofloxacin. PCR, assays were positive for bla NDM-1 and qnrVC in CF638 and TcCF638. Two different class 1 integrons were detected, In127 and In907. In127, featured the genetic array: aadA2-ltr2. Conversely, complex In907 featured, two variable regions (VR); VR-1 consisted of aadB-bla OXA-10 -aadA1cc, whereas, VR-2, featured a gene qnrVC6 108 bp downstream from the ISCR1 and 45 bp, upstream from the qacEΔ1. Expression of qnrVC6 would be on account of a, putative promoter region, detected using the Neural Network Promoter, Prediction program. To the best of our knowledge this constitutes the first report of a qnrVC gene within a complex class 1 integron, and the first report as well of the occurrence of such gene in an NDM-1-producing enterobacterial clinical isolate. Copyright © 2018. Published by Elsevier Ltd.

Quality of Life Questionnaire-Bronchiectasis: final psychometric analyses and determination of minimal important difference scores.

PubMed

Quittner, Alexandra L; O'Donnell, Anne E; Salathe, Matthias A; Lewis, Sandra A; Li, Xiaoming; Montgomery, A Bruce; O'Riordan, Thomas G; Barker, Alan F

2015-01-01

The Quality of Life-Bronchiectasis (QOL-B), a self-administered, patient-reported outcome measure assessing symptoms, functioning and health-related quality of life for patients with non-cystic fibrosis (CF) bronchiectasis, contains 37 items on 8 scales (Respiratory Symptoms, Physical, Role, Emotional and Social Functioning, Vitality, Health Perceptions and Treatment Burden). Psychometric analyses of QOL-B V.3.0 used data from two double-blind, multicentre, randomised, placebo-controlled, phase III trials of aztreonam for inhalation solution (AZLI) in 542 patients with non-CF bronchiectasis and Gram-negative endobronchial infection. Excellent internal consistency (Cronbach's α ≥0.70) and 2-week test-retest reliability (intraclass correlation coefficients ≥0.72) were demonstrated for each scale. Convergent validity with 6 min walk test was observed for Physical and Role Functioning scores. No floor or ceiling effects (baseline scores of 0 or 100) were found for the Respiratory Symptoms scale (primary endpoint of trials). Baseline Respiratory Symptoms scores discriminated between patients based on baseline FEV₁% predicted in only one trial. The minimal important difference score for the Respiratory Symptoms scale was 8.0 points. AZLI did not show efficacy in the two phase III trials. QOL-B responsivity to treatment was assessed by examining changes from baseline QOL-B scores at study visits at which protocol-defined pulmonary exacerbations were reported. Mean Respiratory Symptoms scores decreased 14.0 and 14.2 points from baseline for placebo-treated and AZLI-treated patients with exacerbations, indicating that worsening respiratory symptoms were reflected in clinically meaningful changes in QOL-B scores. Previously established content validity, reliability and responsivity of the QOL-B are confirmed by this final validation study. The QOL-B is available for use in clinical trials and routine clinical practice. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Vancomycin resistant Enterococcus spp. from crows and their environment in metropolitan Washington State, USA: Is there a correlation between VRE positive crows and the environment?

PubMed

Roberts, Marilyn C; No, David B; Marzluff, John M; Delap, Jack H; Turner, Robert

2016-10-15

Vancomycin-resistant enterococci [VRE] have been isolated from municipal, hospital and agricultural wastewater, recreational beaches, wild animals, birds and food animals around the world. In this study, American crows (Corvus brachyrhynchos) from sewage treatment plants (WWTP), dairy farms, and a large roost in a restored wetland with corresponding environmental samples were cultured for VRE. A total of 245 samples [156 crows, 89 environmental] were collected and screened for acquired vanA, vanB and/or intrinsic vanC1 genes. Samples were enriched overnight in BHI supplemented with 20μg/mL aztreonam, 4μg/mL vancomycin and plated on m-Enterococcus agar media supplemented with 6μg/mL vancomycin. Selected colonies were grown on BHI media supplemented with 18μg/mL vancomycin. Of these, 24.5% of the crow and 55% the environmental/cow samples were VRE positive as defined by Enterococcus spp. able to grow on media supplemented with 18μg/mL vancomycin. A total of 122 VRE isolates, 43 crow and 79 environmental isolates were screened, identified to species level using 16S sequencing and further characterized. Four vanA E. faecium and multiple vanC1 E. gallinarum were identified from crows isolated from three sites. E. faecium vanA and E. gallinarum vanC1 along with other Enterococcus spp. carrying vanA, vanB, vanC1 were isolated from three environments. All enterococci were multidrug resistant. Crows were more likely to carry vanA E. faecium than either the cow feces or wetland waters/soils. Comparing E. gallinarum vanC1 from crows and their environment would be useful in determining whether crows share VRE strains with their environment. Copyright © 2016 Elsevier B.V. All rights reserved.

First Report of Prevalence of CTX-M-15-Producing Escherichia coli O25b/ST131 from Iran.

PubMed

Namaei, Mohammad Hasan; Yousefi, Masoud; Ziaee, Masoud; Salehabadi, Alireza; Ghannadkafi, Malaknaz; Amini, Elham; Askari, Parvin

2017-10-01

The emergence of Escherichia coli sequence type 131 (ST131) as a multidrug-resistant and virulent pathogen represents a major challenge to public health globally. Recently, the O25b/ST131 E. coli producing CTX-M-15 with high virulence potential has been reported worldwide, but has received little attention in Iran. This study is the first in Iran to specifically determine the spread of the O25b/ST131 clone producing CTX-M-15 among E. coli isolates belonging to the B2 phylogenetic group. ST131 clone in phylogenetic group B2 was detected based on PCR detection of ST131-specific single-nucleotide polymorphisms in mdh and gyrB. O25b/ST131 E. coli clone was confirmed utilizing O25b/ST131 clone allele-specific PCR for the pabB gene. All group B2 E. coli isolates were characterized based on antibiotic susceptibility, extended-spectrum β-lactamase (ESBL) enzymes, and virulence traits. Our results demonstrated that 38 out of the 154 B2 group isolates (24.7%) were identified as belonging to the ST131 clone. Furthermore, of these, 28 isolates (73.6%) were detected as O25b/ST131 clone. Antibiotic resistance of ST131 E. coli isolates to ciprofloxacin, gentamicin, cefotaxime, and aztreonam was significantly higher than non-ST131 isolates. Almost all of the O25b/ST131 isolates with the ability for ESBL production were reported as CTX-M-15 producing (95.5%). Our results showed that the most prevalent virulence trait in ST131 clone was ompT (94.7%). This study is the first to report the prevalence of the CTX-M-15-producing O25b/ST131 E. coli in Iran. Our findings reinforce the surveillance of dissemination of ST131 E. coli clone as a major drug-resistant pathogen and an important new public health threat.

Molecular characteristic of mcr-1 producing Escherichia coli in a Chinese university hospital.

PubMed

He, Qing-Wen; Xu, Xiao-Hong; Lan, Fang-Jun; Zhao, Zhi-Chang; Wu, Zhi-Yun; Cao, Ying-Ping; Li, Bin

2017-04-19

Colistin has been considered as a last-line treatment option in severe infections caused by multidrug-resistant (MDR) gram-negative pathogens. However, the emergence of the mobile colistin resistance gene (mcr-1) has challenged this viewpoint. The aim of this study is to explore the prevalence of mcr-1 in Escherichia coli (E. coli) in a Chinese teaching hospital, and investigate their molecular characteristics. A total of 700 E. coli isolates were used to screen mcr-1 by PCR and sequencing in a Chinese university hospital from August 2014 to August 2015. Susceptibility test of mcr-1-producing isolates was determined by Vitek -2 Compact system. 26 virulence factors (VFs), phylogenetic groups, Multi-locus sequence typing (MLST), and DNA Fingerprinting (ERIC-PCR) of strains were investigated by PCR. Four (0.6%) mcr-1 producing E. coli isolates were found in this study. The results of antibiotic susceptibility test showed that all four isolates were resistant to colistin, ciprofloxacin, levofloxacin, cefazolin, and trimethoprim/sulfamethoxazole, and were susceptible to amikacin, ertapenem and imipenem. In addition, all 4 isolates exhibited high-level resistance to aztreonam, cefotaxime and gentamicin. The numbers of VFs contained in mcr-1 positive isolates were no more than 4 in our study. MLST result demonstrated that these isolates were assigned to two sequence types: ST156 and ST167. The result of phylogenetic analysis showed that four mcr-1-positive isolates belong to two phylogenetic groups: A and B1 group. ERIC-PCR showed that four mcr-1 positive strains were categorized into three different genotypes. Our study demonstrated a low prevalence of mcr-1 in E. coli clinical isolates in a Chinese teaching hospital, and we have gained insights into the molecular characteristics of these mcr-1-positive strains. Increasing the surveillance of these infections, as well as taking effective infection control measures are urgently needed to take to control the transmission of mcr-1 gene.

Impact of a clinical guideline for prescribing antibiotics to inpatients reporting penicillin or cephalosporin allergy.

PubMed

Blumenthal, Kimberly G; Shenoy, Erica S; Varughese, Christy A; Hurwitz, Shelley; Hooper, David C; Banerji, Aleena

2015-10-01

Self-reported penicillin allergy infrequently reflects an inability to tolerate penicillins. Inpatients reporting penicillin allergy receive alternative antibiotics that might be broader spectrum, more toxic, or less effective. To develop and assess a clinical guideline for the general inpatient provider that directs taking a history and prescribing antibiotics for patients with penicillin or cephalosporin allergy. A guideline was implemented to assist providers with assessing allergy history and prescribing antibiotics for patients with reported penicillin or cephalosporin allergy. The guideline used a standard 2-step graded challenge or test dose. A quasi-experimental study was performed to assess safety, feasibility, and impact on antibiotic use by comparing treatment 21 months before guideline implementation with 12 months after guideline implementation. Significantly more test doses to β-lactam antibiotics were performed monthly after vs before guideline implementation (median 14.5, interquartile range 13-16.25, vs 2, interquartile range 1-3.25, P < .001). Seven adverse drug reactions occurred during guideline-driven test doses, with no significant difference in rate (3.9% vs 6.1%, P = .44) or severity (P > .5) between periods. Guideline-driven test doses decreased alternative antimicrobial therapy after the test dose, including vancomycin (68.3% vs 37.2%, P < .001), aztreonam (11.5% vs 0.5%, P < .001), aminoglycosides (6.0% vs 1.1%, P = .004), and fluoro quinolones (15.3% vs 3.3%, P < .001). The implementation of an inpatient antibiotic prescribing guideline for patients with penicillin or cephalosporin allergy was associated with an almost 7-fold increase in the number of test doses to β-lactams without increased adverse drug reactions. Patients assessed with guideline-driven test doses were observed to have significantly decreased alternative antibiotic exposure. Copyright © 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Gut resistome development in healthy twin pairs in the first year of life.

PubMed

Moore, Aimee M; Ahmadi, Sara; Patel, Sanket; Gibson, Molly K; Wang, Bin; Ndao, Malick I; Deych, Elena; Shannon, William; Tarr, Phillip I; Warner, Barbara B; Dantas, Gautam

2015-01-01

The early life of the human host marks a critically important time for establishment of the gut microbial community, yet the developmental trajectory of gut community-encoded resistance genes (resistome) is unknown. We present a longitudinal study of the fecal antibiotic resistome of healthy amoxicillin-exposed and antibiotic-naive twins and their mothers during the first year of life. We extracted metagenomic DNA (mgDNA) from fecal samples collected from three healthy twin pairs at three timepoints (1 or 2 months, 6 or 7 months, and 11 months) and from their mothers (collected at delivery). The mgDNA was used to construct metagenomic expression libraries in an Escherichia coli host. These libraries were screened for antibiotic resistance, and functionally selected resistance genes were sequenced and annotated. A diverse fecal resistome distinct from the maternal resistome was apparent by 2 months of age, and infants' fecal resistomes included resistance to clinically important broad-spectrum beta-lactam antibiotics (e.g., piperacillin-tazobactam, aztreonam, cefepime) not found in their mothers. Dissemination of resistance genes among members of a given family was positively correlated with sharing of those same resistance genes between unrelated families, potentially identifying within-family sharing as a marker of resistance genes emerging in the human community at large. Finally, we found a distinct developmental trajectory for a community-encoded function: chloramphenicol resistance. All study subjects at all timepoints harbored chloramphenicol resistance determinants, but multidrug efflux pumps (rarely found in mothers) were the primary effectors of chloramphenicol resistance in young infants. Chloramphenicol acetyltransferases were more common in mothers than in infants and were found in nearly all the infants at later timepoints. Our results suggest that healthy 1-2-month-old infants' gut microbes harbor clinically relevant resistance genes distinct from those of their mothers, and that family-specific shared environmental factors early in life shape resistome development.

First Penicillin-Binding Protein Occupancy Patterns of β-Lactams and β-Lactamase Inhibitors in Klebsiella pneumoniae.

PubMed

Sutaria, Dhruvitkumar S; Moya, Bartolome; Green, Kari B; Kim, Tae Hwan; Tao, Xun; Jiao, Yuanyuan; Louie, Arnold; Drusano, George L; Bulitta, Jürgen B

2018-06-01

Penicillin-binding proteins (PBPs) are the high-affinity target sites of all β-lactam antibiotics in bacteria. It is well known that each β-lactam covalently binds to and thereby inactivates different PBPs with various affinities. Despite β-lactams serving as the cornerstone of our therapeutic armamentarium against Klebsiella pneumoniae , PBP binding data are missing for this pathogen. We aimed to generate the first PBP binding data on 13 chemically diverse and clinically relevant β-lactams and β-lactamase inhibitors in K. pneumoniae PBP binding was determined using isolated membrane fractions from K. pneumoniae strains ATCC 43816 and ATCC 13883. Binding reactions were conducted using β-lactam concentrations from 0.0075 to 256 mg/liter (or 128 mg/liter). After β-lactam exposure, unbound PBPs were labeled by Bocillin FL. Binding affinities (50% inhibitory concentrations [IC 50 ]) were reported as the β-lactam concentrations that half-maximally inhibited Bocillin FL binding. PBP occupancy patterns by β-lactams were consistent across both strains. Carbapenems bound to all PBPs, with PBP2 and PBP4 as the highest-affinity targets (IC 50 , <0.0075 mg/liter). Preferential PBP2 binding was observed by mecillinam (amdinocillin; IC 50 , <0.0075 mg/liter) and avibactam (IC 50 , 2 mg/liter). Aztreonam showed high affinity for PBP3 (IC 50 , 0.06 to 0.12 mg/liter). Ceftazidime bound PBP3 at low concentrations (IC 50 , 0.06 to 0.25 mg/liter) and PBP1a/b at higher concentrations (4 mg/liter), whereas cefepime bound PBPs 1 to 4 at more even concentrations (IC 50 , 0.015 to 2 mg/liter). These PBP binding data on a comprehensive set of 13 clinically relevant β-lactams and β-lactamase inhibitors in K. pneumoniae enable, for the first time, the rational design and optimization of double β-lactam and β-lactam-β-lactamase inhibitor combinations. Copyright © 2018 American Society for Microbiology.

Antibiotic content of selective culture media for isolation of Capnocytophaga species from oral polymicrobial samples.

PubMed

Ehrmann, E; Jolivet-Gougeon, A; Bonnaure-Mallet, M; Fosse, T

2013-10-01

In oral microbiome, because of the abundance of commensal competitive flora, selective media with antibiotics are necessary for the recovery of fastidious Capnocytophaga species. The performances of six culture media (blood agar, chocolate blood agar, VCAT medium, CAPE medium, bacitracin chocolate blood agar and VK medium) were compared with literature data concerning five other media (FAA, LB, TSBV, CapR and TBBP media). To understand variable growth on selective media, the MICs of each antimicrobial agent contained in this different media (colistin, kanamycin, trimethoprim, trimethoprim-sulfamethoxazole, vancomycin, aztreonam and bacitracin) were determined for all Capnocytophaga species. Overall, VCAT medium (Columbia, 10% cooked horse blood, polyvitaminic supplement, 3·75 mg l(-1) of colistin, 1·5 mg l(-1) of trimethoprim, 1 mg l(-1) of vancomycin and 0·5 mg l(-1) of amphotericin B, Oxoid, France) was the more efficient selective medium, with regard to the detection of Capnocytophaga species from oral samples (P < 0·001) and the elimination of commensal clinical species (P < 0·001). The demonstrated superiority of VCAT medium, related to its antibiotic content, made its use indispensable for the optimal isolation of Capnocytophaga species from polymicrobial samples. Isolation of Capnocytophaga species is important for the proper diagnosis and treatment of the systemic infections they cause and for epidemiological studies of periodontal flora. We showed that in pure culture, a simple blood agar allowed the growth of all Capnocytophaga species. Nonetheless, in oral samples, because of the abundance of commensal competitive flora, selective media with antibiotics are necessary for the recovery of Capnocytophaga species. The demonstrated superiority of VCAT medium made its use essential for the optimal detection of this bacterial genus. This work showed that extreme caution should be exercised when reporting the isolation of Capnocytophaga species from oral polymicrobial samples, because the culture medium is a determining factor. © 2013 The Society for Applied Microbiology.

Characterization of the modified Hodge test-positive isolates of Enterobacteriaceae in Taiwan.

PubMed

Hung, Kuei-Hsiang; Yan, Jing-Jou; Lu, Jang-Jih; Chen, Hung-Mo; Wu, Jiunn-Jong

2013-02-01

The modified Hodge test is a phenotypic test to detect KPC-type carbapenemase producers among Enterobacteriaceae, as recommended by the Clinical Laboratory Standards Institute. However, false positive results were reported. In this study, we aimed to large-scale investigate the characterization of the modified Hodge test-positive isolates of Enterobacteriaceae collected between 2006 and 2010 in Taiwan. Fifty-six isolates, including 24 Enterobacter cloacae, 17 Escherichia coli, 10 Klebsiella pneumoniae, and 5 Citrobacter freundii, tested positive with the modified Hodge test. The in vitro activities of 10 antimicrobial agents were determined by the agar dilution method. Boronic acid combined-disk test was used to further confirm the KPC producers. Phenotype of ESBL, AmpC, class B carbapenemases, and profile of outer membrane proteins were investigated by the confirmatory test, boronic acid disk method, 2-mercaptopropionic acid double-disk method, and urea/sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. β-lactamase genes were examined by PCR and sequencing. These isolates were resistant to ceftazidime (100%), aztreonam (82.1%), ertapenem (64.3%), gentamicin (53.6%), ciprofloxacin (50%), levofloxacin (48.2%), cefepime (19.6%), imipenem (16.1%), meropenem (12.5%), and amikacin (8.9%). Phenotypic testing among isolates revealed the production of ESBLs, metallo-β-lactamases (MBLs), and AmpC in 10 (17.9%), 16 (28.6%), and 12 (44.4%) isolates, respectively. Carbapenemase and non-carbapenemase β-lactamase genes bla(TEM-1), bla(SHV), bla(CTX-M), bla(IMP-8), bla(CMY-2), and bla(DHA-1) were found in 32 (57.1%), 19 (33.9%), 4 (7.1%), 16 (28.6%), 14 (25%), and 5 (8.9%) of the strains, respectively. No class A and D carbapenemase genes were detected. Outer membrane protein profile showed obviously decreased expression in 49 (87.5%) isolates with positive result of modified Hodge test. Our data show that ESBLs, AmpC, and imipenemase-8 (IMP-8) carbapenemase coupled with decreased expression of outer membrane protein were prevalent in Enterobacteriaceae isolates testing positive for the modified Hodge test in Taiwan. Copyright © 2012. Published by Elsevier B.V.

Prevalence and clonal relationship of ESBL-producing Salmonella strains from humans and poultry in northeastern Algeria.

PubMed

Djeffal, Samia; Bakour, Sofiane; Mamache, Bakir; Elgroud, Rachid; Agabou, Amir; Chabou, Selma; Hireche, Sana; Bouaziz, Omar; Rahal, Kheira; Rolain, Jean-Marc

2017-05-15

The aims of this study were to investigate Salmonella contamination in broiler chicken farms and slaughterhouses, to assess the antibiotic resistance profile in avian and human Salmonella isolates, and to evaluate the relationship between avian and human Extended Spectrum β-Lactamase (ESBL)-producing isolates. Salmonella was screened in different sample matrices collected at thirty-two chicken farms and five slaughterhouses. The human isolates were recovered from clinical specimens at the University Teaching Hospital of Constantine (UTH). All suspected colonies were confirmed by MALDI-TOF (Matrix Assisted Laser Desorption Ionization Time OF light) and serotyped. Susceptibility testing against 13 antibiotics including, amoxicillin/clavulanic acid, ticarcillin, cefoxitin, cefotaxime, aztreonam, imipenem, ertapenem, gentamicin, amikacin, ciprofloxacin, colistin, trimethoprim/sulfamethoxazole and fosfomycin, was performed using the disk diffusion method on Mueller-Hinton agar. ESBL-production was screened by the double-disk synergy test and confirmed by molecular characterization using PCR (polymerase chain reaction) amplification and sequencing of ESBL encoding genes. Clonality of the avian and human strains was performed using the Multi Locus Sequencing Typing method (MLST). Forty-five isolated avian Salmonella strains and 37 human collected ones were studied. Five S. enterica serotypes were found in avian isolates (mainly Kentucky) and 9 from human ones (essentially Infantis). 51.11% and 26.6% of the avian isolates were resistant to ciprofloxacin and cefotaxime, respectively, whereas human isolates were less resistant to these antibiotics (13.5% to ciprofloxacin and 16.2% to cefotaxime). Eighteen (12 avian and 6 human) strains were found to produce ESBLs, which were identified as bla CTX-M-1 (n = 12), bla CTX-M-15 (n = 5) and bla TEM group (n = 8). Interestingly, seven of the ESBL-producing strains (5 avian and 2 human) were of the same ST (ST15) and clustered together, suggesting a common origin. The results of the combined phenotypic and genotypic analysis found in this study suggest a close relationship between human and avian strains and support the hypothesis that poultry production may play a role in the spread of multidrug-resistant Salmonella in the human community within the study region.

Genetic characterization of antibiotic resistance in enteropathogenic Escherichia coli carrying extended-spectrum beta-lactamases recovered from diarrhoeic rabbits.

PubMed

Poeta, P; Radhouani, H; Gonçalves, A; Figueiredo, N; Carvalho, C; Rodrigues, J; Igrejas, G

2010-05-01

A total of 52 Escherichia coli strains isolated from diarrhoeic rabbits were investigated for their enteropathogenic E. coli (EPEC) pathotype by PCR amplification of eae and bfp virulence genes. A total of 22 EPEC isolates were identified, serotyped and studied for antibiotic resistance and screened for the detection of extended-spectrum beta-lactamases (ESBLs). The EPEC isolates belonged to three serogroups (O26, O92 and O103). The most common serogroup (O103:K-:H2) was observed among 17 EPEC strains, the O92:K-serogroup in three isolates (the antibiotic sensitive ones) and the remaining O26:K-serogroup in two isolates (the ESBLs isolates). Resistances to ampicillin and tetracycline were the most frequent and detected followed by resistance to nalidixic acid, streptomycin, trimethoprim-sulphamethoxazole, cefoxitin, gentamicin and ciprofloxacin. All the isolates were sensitive for amikacin, ceftazidime, aztreonam, imipenem, chloramphenicol, tobramycin and amoxicillin + clavulanic acid. Two isolates recovered from two adult animals showed an intermediate susceptibility to cefotaxime, and a positive screening test for ESBL was demonstrated in both. The bla(TEM) gene was demonstrated in the majority of ampicillin-resistant isolates. The aac(3)-II or aac(3)-IV genes were detected in the four gentamicin-resistant isolates. In addition, the aadA gene was detected in 60% of streptomycin-resistant isolates. The tet(A) or tet(B) genes were identified in all tetracycline-resistant isolates. A total of nine EPEC isolates showed the phenotype SXT-resistant, and the sul1 and/or sul2 and/or sul3 genes were detected in all of them. Our findings showed that the molecular detection by the eae and bfp genes by PCR followed by serotyping is useful for monitoring trends in EPEC infections of rabbits allowing the identification of their possible reservoirs. The detection of genes involved in the resistance to antibiotics of different families in a relatively high proportion of faecal E. coli isolates of rabbits is of great interest and could be considered a serious public health problem.

Design and Study of Efflux Function of EGFP Fused MexAB-OprM Membrane Transporter in Pseudomonas aeruginosa Using Fluorescence Spectroscopy

PubMed Central

Ding, Feng; Lee, Kerry J.; Vahedi-Faridi, Ardeschir; Yoneyama, Hiroshi; Osgood, Christopher J.; Xu, Xiao-Hong Nancy

2014-01-01

Multidrug membrane transporters (efflux pumps) can selectively extrude a variety of structurally and functionally diverse substrates (e.g., chemotoxics, antibiotics), leading to multidrug resistance (MDR) and ineffective treatment of a wide variety of diseases. In this study, we have designed and constructed fusion gene (egfp-mexB) of N-terminal mexB with C-terminal egfp, inserted it into a plasmid vector (pMMB67EH), and successfully expressed it in ΔMexB (MexB deletion) strain of Pseudomonas aeruginosa to create a new strain that expresses MexA-(EGFP-MexB)-OprM. We characterized the fusion gene using gel electrophoresis and DNA sequencing, and determined their expression in live cells by measuring the fluorescence of EGFP in single live cells using fluorescence microscopy. Efflux function of the new strain was studied by measuring its accumulation kinetics of ethidium bromide (EtBr, a pump substrate) using fluorescence spectroscopy, which was compared with the cells (WT, ΔMexM, ΔABM, and nalB1) with various expression levels of MexAB-OprM. The new strain shows 6-fold lower accumulation rates of EtBr (15 μM) than ΔABM, 4-fold lower than ΔMexB, but only 1.1-fold higher than WT. As EtBr concentration increases to 40 μM, the new strain has nearly the same accumulation rate of EtBr as ΔMexB, but 1.4-fold higher than WT. We observed the nearly same level of inhibitory effect of CCCP (carbonyl cyanide-m-chlorophenylhydrazone) on the efflux of EtBr by the new strain and WT. Antibiotic susceptibility study shows that the minimum inhibitory concentrations (MICs) of aztreonam (AZT) and chloramphenicol (CP) for the new strain are 6-fold or 3-fold lower than WT, respectively, and 2-fold higher than those of ΔMexB. Taken together, the results suggest that the fusion protein partially retains the efflux function of MexAB-OprM. Modeled structure of the fusion protein shows that the position and orientation of the N-terminal fused EGFP domain may either partially block the translocation pore or restrict the movement of the individual pump domains, which leads to partially restrict efflux activity. PMID:24781334

In Vitro Activity of Delafloxacin and Microbiological Response against Fluoroquinolone-Susceptible and Nonsusceptible Staphylococcus aureus Isolates from Two Phase 3 Studies of Acute Bacterial Skin and Skin Structure Infections

PubMed Central

Lawrence, L.; Quintas, M.; Woosley, L.; Flamm, R.; Tseng, C.; Cammarata, S.

2017-01-01

ABSTRACT Delafloxacin is an investigational anionic fluoroquinolone antibiotic with broad-spectrum in vitro activity, including activity against Gram-positive organisms, Gram-negative organisms, atypical organisms, and anaerobes. The in vitro activity of delafloxacin and the percent microbiological response in subjects infected with fluoroquinolone-susceptible and nonsusceptible Staphylococcus aureus isolates were determined from two global phase 3 studies of delafloxacin versus vancomycin plus aztreonam in patients with acute bacterial skin and skin structure infections (ABSSSI). Patients from 23 countries, predominately the United States but also Europe, South America, and Asia, were enrolled. The microbiological intent-to-treat (MITT) population included 1,042 patients from which 685 S. aureus isolates were submitted for identification and susceptibility testing per CLSI guidelines at the central laboratory (JMI Laboratories, North Liberty, IA). The comparator fluoroquinolone antibiotics included levofloxacin and ciprofloxacin. Nonsusceptibility to these antibiotics was determined using CLSI breakpoints. S. aureus isolates were 33.7% levofloxacin nonsusceptible (LVX-NS). The delafloxacin MIC90 values against levofloxacin-nonsusceptible S. aureus, methicillin-resistant S. aureus (MRSA), and methicillin-susceptible S. aureus isolates were all 0.25 μg/ml. Delafloxacin demonstrated high rates of microbiological response against LVX-NS isolates as well as isolates with documented mutations in the quinolone resistance-determining region (QRDR). S. aureus was eradicated or presumed eradicated in 98.4% (245/249) of delafloxacin-treated patients. Similar eradication rates were observed for delafloxacin-treated subjects with levofloxacin-nonsusceptible S. aureus isolates (80/81; 98.8%) and MRSA isolates (70/71; 98.6%). Microbiological response rates of 98.6% were observed with delafloxacin-treated subjects with S. aureus isolates with the S84L mutation in gyrA and the S80Y mutation in parC, the most commonly observed mutations in global phase 3 studies. The data suggest that delafloxacin could be a good option for the treatment of infections caused by S. aureus isolates causing ABSSSI, including MRSA isolates, where high rates of ciprofloxacin and levofloxacin nonsusceptibility are observed. (The phase 3 studies described in this paper have been registered at ClinicalTrials.gov under identifiers NCT01984684 and NCT01811732.) PMID:28630189

In Vitro Activity of Delafloxacin and Microbiological Response against Fluoroquinolone-Susceptible and Nonsusceptible Staphylococcus aureus Isolates from Two Phase 3 Studies of Acute Bacterial Skin and Skin Structure Infections.

PubMed

McCurdy, S; Lawrence, L; Quintas, M; Woosley, L; Flamm, R; Tseng, C; Cammarata, S

2017-09-01

Delafloxacin is an investigational anionic fluoroquinolone antibiotic with broad-spectrum in vitro activity, including activity against Gram-positive organisms, Gram-negative organisms, atypical organisms, and anaerobes. The in vitro activity of delafloxacin and the percent microbiological response in subjects infected with fluoroquinolone-susceptible and nonsusceptible Staphylococcus aureus isolates were determined from two global phase 3 studies of delafloxacin versus vancomycin plus aztreonam in patients with acute bacterial skin and skin structure infections (ABSSSI). Patients from 23 countries, predominately the United States but also Europe, South America, and Asia, were enrolled. The microbiological intent-to-treat (MITT) population included 1,042 patients from which 685 S. aureus isolates were submitted for identification and susceptibility testing per CLSI guidelines at the central laboratory (JMI Laboratories, North Liberty, IA). The comparator fluoroquinolone antibiotics included levofloxacin and ciprofloxacin. Nonsusceptibility to these antibiotics was determined using CLSI breakpoints. S. aureus isolates were 33.7% levofloxacin nonsusceptible (LVX-NS). The delafloxacin MIC 90 values against levofloxacin-nonsusceptible S. aureus , methicillin-resistant S. aureus (MRSA), and methicillin-susceptible S. aureus isolates were all 0.25 μg/ml. Delafloxacin demonstrated high rates of microbiological response against LVX-NS isolates as well as isolates with documented mutations in the quinolone resistance-determining region (QRDR). S. aureus was eradicated or presumed eradicated in 98.4% (245/249) of delafloxacin-treated patients. Similar eradication rates were observed for delafloxacin-treated subjects with levofloxacin-nonsusceptible S. aureus isolates (80/81; 98.8%) and MRSA isolates (70/71; 98.6%). Microbiological response rates of 98.6% were observed with delafloxacin-treated subjects with S. aureus isolates with the S84L mutation in gyrA and the S80Y mutation in parC , the most commonly observed mutations in global phase 3 studies. The data suggest that delafloxacin could be a good option for the treatment of infections caused by S. aureus isolates causing ABSSSI, including MRSA isolates, where high rates of ciprofloxacin and levofloxacin nonsusceptibility are observed. (The phase 3 studies described in this paper have been registered at ClinicalTrials.gov under identifiers NCT01984684 and NCT01811732.). Copyright © 2017 McCurdy et al.

Antimicrobial susceptibilities of Proteus mirabilis: a longitudinal nationwide study from the Taiwan surveillance of antimicrobial resistance (TSAR) program.

PubMed

Wang, Jann-Tay; Chen, Pei-Chen; Chang, Shan-Chwen; Shiau, Yih-Ru; Wang, Hui-Ying; Lai, Jui-Fen; Huang, I-Wen; Tan, Mei-Chen; Lauderdale, Tsai-Ling Yang

2014-09-05

Longitudinal nationwide data on antimicrobial susceptibility in Proteus mirabilis from different sources are rare. The effects of the revised Clinical and Laboratory Standards Institute (CLSI) β-lactam breakpoints on susceptibility rates and on detecting extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase-producers in this species are also seldom evaluated. The present study analyzed data from the Taiwan Surveillance of Antimicrobial Resistance program to address these issues. Isolates were collected biennially between 2002 and 2012 from 25 to 28 hospitals in Taiwan. Minimum inhibitory concentrations (MIC) were determined by reference broth microdilution method. All isolates with aztreonam, ceftazidime, or cefotaxime MIC ≥ 2 mg/L were checked for the presence of ESBL by CLSI confirmatory test and subjected to ESBL and AmpC β-lactamases gene detection by PCR. Univariate and multivariate analyses were performed. Between 2002 and 2012, a total of 1157 P. mirabilis were studied. Susceptibility to cefotaxime, ceftazidime, and ciprofloxacin decreased significantly during the past decade, from 92.6% to 81.7%, 100% to 95.2%, and 80.1% to 53.8%, respectively (P < 0.01). The revised CLSI breakpoints had significant impact on susceptibility to cefazolin (2009 vs. current breakpoints, 71.9% vs. 0.9%) and imipenem (99.8% vs. 55.1%) (P < 0.001 for both). However, using the 2014 cefazolin breakpoints for urinary tract infections, 81.2% of the urine isolates were susceptible. Susceptibilities of isolates from different specimen types were mostly similar but outpatient isolates were more susceptible than inpatient isolates. The overall prevalence of ESBL- and AmpC- producers was 8.2% and 4.7%, respectively, but AmpC carriage increased significantly over the years (from 0 to 7.0%, P < 0.001). ESBL and AmpC β-lactamase-producers were more likely to be found in elderly and ICU patients. The predominant ESBL and AmpC β-lactamase genes were CTX-M- and CMY- types, respectively. A significant decrease in susceptibility to 3rd-generation cephalosporins and ciprofloxacin occurred in P. mirabilis from Taiwan in the past decade. The prevalence of ESBL remained stable but AmpC β-lactamase-producing P. mirabilis increased significantly. Cefotaxime was a better surrogate than ceftazidime for predicting the presence of these β-lactamases. Continuous surveillance on antimicrobial resistance and associated resistance mechanisms in P. mirabilis is warranted.

Comparison of beta-lactam regimens for the treatment of gram-negative pulmonary infections in the intensive care unit based on pharmacokinetics/pharmacodynamics.

PubMed

Burgess, David S; Frei, Christopher R

2005-11-01

This study utilized pharmacokinetics/pharmacodynamics to compare beta-lactam regimens for the empirical and definitive treatment of gram-negative pulmonary infections in the ICU. Susceptibility data were extracted from the 2002 Intensive Care Unit Surveillance System (ISS) and pharmacokinetic parameters were obtained from published human studies. Monte Carlo simulation was used to model the free percent time above the MIC (free %T > MIC) for 18 beta-lactam regimens against all gram-negative isolates, Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii. The cumulative fraction of response (CFR) was determined for bacteriostatic and bactericidal targets (free %T > MIC): penicillins (> or = 30/50%), cephalosporins/monobactams (> or = 40/70%) and carbapenems (> or = 20/40%). The 2002 ISS database contained MICs for 2408 gram-negative isolates including 1430 Enterobacteriaceae, 799 P. aeruginosa, and 179 A. baumannii. Imipenem had the highest percentage susceptible for all gram-negatives, Enterobacteriaceae and A. baumannii, while piperacillin/tazobactam had the highest percentage susceptible for P. aeruginosa. For empirical therapy, imipenem 0.5 g every 6 h, cefepime 2 g every 8 h and ceftazidime 2 g every 8 h demonstrated the highest CFR. For definitive therapy, imipenem 0.5 g every 6 h, ertapenem 1 g daily and cefepime 2 g every 8 h, cefepime 1 g every 8 h and cefepime 1 g every 12 h had the highest bactericidal CFR against Enterobacteriaceae; ceftazidime 2 g every 8 h, cefepime 2 g every 8 h, piperacillin/tazobactam 3.375 g every 4 h, ceftazidime 1 g every 8 h and aztreonam 1 g every 8 h against P. aeruginosa; and imipenem 0.5 g every 6 h, ticarcillin/clavulanate 3.1 g every 4 h, ceftazidime 2 g every 8 h, cefepime 2 g every 8 h and ticarcillin/clavulanate 3.1 g every 6 h against A. baumannii. Based on pharmacokinetics/pharmacodynamics, imipenem 0.5 g every 6 h, cefepime 2 g every 8 h and ceftazidime 2 g every 8 h should be the preferred beta-lactam regimens for the empirical treatment of gram-negative pulmonary infections in the ICU. The order of preference varied against Enterobacteriaceae, P. aeruginosa and A. baumannii.

[Molecular epidemiology of beta-lactamases in ceftazidime-resistant Pseudomonas aeruginosa isolates].

PubMed

Er, Halil; Altındiş, Mustafa; Aşık, Gülşah; Demir, Cengiz

2015-04-01

Pseudomonas aeruginosa is an important opportunistic pathogen that cause mainly nosocomial infections especially in the immunocompromised patients, the elderly and patients with severe burns. The bacterial feature of developing high degree of resistance against several antibiotics leads to increased morbidity and mortality of P.aeruginosa infections. The aims of this study were to investigate the antibiotic susceptibilities of P.aeruginosa strains isolated from hospitalized patients and to determine the presence of resistance enzymes namely PER, GES, KPC, VIM, IMP and OXA. A total of 195 P.aeruginosa strains isolated from different clinical samples (29 sputum, 67 wound, 53 tracheal aspirate, 23 blood, 18 urine, 3 cerebrospinal fluid, 2 pleural fluid) of inpatients (134 male, 61 female) in Afyon Kocatepe University School of Medicine Hospital between 2010-2012, were included in the study. The isolates were identified by conventional methods and automated systems (VITEK 2, BioMerieux, France), and their antibiotic susceptibilities were detected by disk diffusion and E-test methods. Inducible beta-lactamase (IBL), extended-spectrum beta-lactamase (ESBL) and metallo-beta-lactamase (MBL) productions of the isolates were phenotypically investigated by double disk induction, double disk synergy and E-test methods, respectively. The presence of resistance genes encoding PER, GES, KPC, VIM, IMP and OXA enzymes were determined by real-time polymerase chain reaction, and sequence analysis was applied to positive samples. In our study, the antibiotic resistance rates of 195 P.aeruginosa strains were found as follows: ceftazidime 100%, tazobactam/piperacillin 90.8%, aztreonam 60.5%, cefepime 50.2%, imipenem 48.2%, meropenem 47.2%, ofloxacin 47.2%, piperacillin 44.1%, levofloxacin 31.3%, ciprofloxacin 26.2%, gentamicin 11.8%, amikacin 8.7% and tobramycin 6.2%. With the use of phenotypical methods, IBL, ESBL and MBL production rates in the isolates were detected as 89.2% (174/195), 30.7% (60/195) and 26.7% (52/195), respectively. Molecular studies showed that, five strains harboured OXA-10, four OXA-14, four VIM-2, two IMP-1, 26 GES-1 and 87 ABC transporter permease genes, while PER and KPC genes were not detected in any of the isolates. In conclusion, it was considered that the detection of beta-lactamase genes in bacteria and the identification of beta-lactamase types may provide facilities in selection of antibiotics, monitorization of therapy, prevention of resistance development of infection control programs.

Tigecycline activity against metallo-β-lactamase-producing bacteria.

PubMed

Kumar, Simit; Bandyopadhyay, Maitreyi; Mondal, Soma; Pal, Nupur; Ghosh, Tapashi; Bandyopadhyay, Manas; Banerjee, Parthajit

2013-10-01

[corrected] Treatment of serious life-threatening multi-drug-resistant organisms poses a serious problem due to the limited therapeutic options. Tigecycline has been recently marketed as a broad-spectrum antibiotic with activity against both gram-positive and gram-negative bacteria. Even though many studies have demonstrated the activity of tigecycline against ESBL-producing Enterobacteriaceae, its activity is not well-defined against micro-organisms producing metallo-β-lactamases (MBLs), as there are only a few reports and the number of isolates tested is limited. The aim of the present study was to evaluate the activity of tigecycline against MBL-producing bacterial isolates. The isolates were tested for MBL production by (i) combined-disk test, (ii) double disc synergy test (DDST), (iii) susceptibility to aztreonam (30 μg) disk. Minimum inhibitory concentration to tigecycline was determined according to agar dilution method as per Clinical Laboratory Standards Institute (CLSI) guidelines. Disc diffusion susceptibility testing was also performed for all these isolates using tigecycline (15 μg) discs. Among the total 308 isolates included in the study, 99 were found to be MBL producers. MBL production was observed mostly in isolates from pus samples (40.47%) followed by urine (27.4%) and blood (13.09%). MBL production was observed in E. coli (41.48%), K. pneumoniae (26.67%), Proteus mirabilis (27.78%), Citrobacter spp. (41.67%), Enterobacter spp. (25.08%), and Acinetobacter spp. (27.27%). The result showed that tigecycline activity was unaffected by MBL production and it was showed almost 100% activity against all MBL-producing isolates, with most of the isolates exhibiting an MIC ranging from 0.25-8 μg/ml, except 2 MBL-producing E. coli isolates who had an MIC of 8 μg/ml. To conclude, tigecycline was found to be highly effective against MBL-producing Enterobacteriaceae and acinetobacter isolates, but the presence of resistance among organisms, even before the mass usage of the drug, warrants the need of its usage as a reserve drug. The study also found that the interpretative criteria for the disc diffusion method, recommended by the FDA, correlates well with the MIC detection methods. So, the microbiology laboratories might use the relatively easier method of disc diffusion, as compared to the comparatively tedious method of MIC determination.

Trans-Cinnamaldehyde and Eugenol Increase Acinetobacter baumannii Sensitivity to Beta-Lactam Antibiotics.

PubMed

Karumathil, Deepti P; Nair, Meera Surendran; Gaffney, James; Kollanoor-Johny, Anup; Venkitanarayanan, Kumar

2018-01-01

Multi-drug resistant (MDR) Acinetobacter baumannii is a major nosocomial pathogen causing a wide range of clinical conditions with significant mortality rates. A. baumannii strains are equipped with a multitude of antibiotic resistance mechanisms, rendering them resistant to most of the currently available antibiotics. Thus, there is a critical need to explore novel strategies for controlling antibiotic resistance in A. baumannii . This study investigated the efficacy of two food-grade, plant-derived antimicrobials (PDAs), namely trans -cinnamaldehyde (TC) and eugenol (EG) in decreasing A. baumannii 's resistance to seven β-lactam antibiotics, including ampicillin, methicillin, meropenem, penicillin, aztreonam, amoxicillin, and piperacillin. Two MDR A. baumannii isolates (ATCC 17978 and AB 251847) were separately cultured in tryptic soy broth (∼6 log CFU/ml) containing the minimum inhibitory concentration (MIC) of TC or EG with or without the MIC of each antibiotic at 37°C for 18 h. A. baumannii strains not exposed to the PDAs or antibiotics served as controls. Following incubation, A. baumannii counts were determined by broth dilution assay. In addition, the effect of PDAs on the permeability of outer membrane and efflux pumps in A. baumannii was measured. Further, the effect of TC and EG on the expression of A. baumannii genes encoding resistance to β-lactam antibiotics ( blaP ), efflux pumps ( adeABC ), and multi-drug resistant protein ( mdrp ) was studied using real-time quantitative PCR (RT-qPCR). The experiment was replicated three times with duplicate samples of each treatment and control. The results from broth dilution assay indicated that both TC and EG in combination with antibiotics increased the sensitivity of A. baumannii to all the tested antibiotics ( P < 0.05). The two PDAs inhibited the function of A. baumannii efflux pump, (AdeABC), but did not increase the permeability of its outer membrane. Moreover, RT-qPCR data revealed that TC and EG down-regulated the expression of majority of the genes associated with β-lactam antibiotic resistance, especially blaP and adeABC ( P < 0.05). The results suggest that TC and EG could potentially be used along with β-lactam antibiotics for controlling MDR A. baumannii infections; however, their clinical significance needs to be determined using in vivo studies.

Molecular epidemiology and drug resistant mechanism in carbapenem-resistant Klebsiella pneumoniae isolated from pediatric patients in Shanghai, China.

PubMed

Zhang, Xingyu; Chen, Di; Xu, Guifeng; Huang, Weichun; Wang, Xing

2018-01-01

Infection by carbapenem-resistant Klebsiella pneumoniae (CR-KP) is a public health challenge worldwide, in particular among children, which was associated with high morbidity and mortality rates. There was limited data in pediatric populations, thus this study aimed to investigate molecular epidemiology and drug resistant mechanism of CR-KP strains from pediatric patients in Shanghai, China. A total of 41 clinical CR-KP isolates from sputum, urine, blood or drainage fluid were collected between July 2014 and May 2015 in Shanghai Children's Medical Center. Multilocus sequence typing (MLST), antibiotic susceptibility testing, PCR amplification and sequencing of the drug resistance associated genes were applied to all these isolates. MLST analysis revealed 16 distinct STs identified within the 41 isolates, among which the most frequently represented were ST11(19.5%),ST25(14.6%),ST76(14.6%),ST37(9.8%).One new ST was first identified. All CR-KP isolates showed MDR phenotypes and were resistance to ceftazidime, imipenem, piperacillin / tazobactam, ceftriaxone, ampicillin /sulbactam, aztreonam. They were confirmed as carbapenemase producer, NDM-1 (56.1%, 23/41), IMP (26.8%, 11/41), KPC-2 (22.0%, 9/41) were detected. Of note, two isolates carried simultaneously both NDM-1 and IMP-4. All CR-KP strains contained at least one of extended spectrum β-lactamase genes tested(TEM, SHV, OXA-1, CTX-M group) and six isolates carried both ESBL and AmpC genes(DHA-1). Among the penicllinase and β-lactamase genes, the most frequently one is SHV(92.7%,38/41), followed by TEM-1(68.3%,28/41), CTX-M-14(43.9%,18/41), CTX-M-15(43.9%,14/41), OXA-1(14.6%,6/41). In the present study, NDM-1-producing isolates was the predominant CR-KP strains in children, follow by IMP and KPC-producing strains. NDM-1and IMP-4 were more frequent than KPC-2 and showed a multiclonal background. Those suggested carbapenem-resistant in children is diverse, and certain resistance mechanisms differ from prevalent genotypes in adults in the same region. Knowledge of the molecular epidemiology and drug resistant mechanism of CR-KP can have a profound effect on clinical treatment, infection control measures and public health policies for children.

Distribution of CTX-M group I and group III β-lactamases produced by Escherichia coli and klebsiella pneumoniae in Lahore, Pakistan.

PubMed

Abrar, Samyyia; Vajeeha, Ayesha; Ul-Ain, Noor; Riaz, Saba

2017-02-01

Extended-spectrum-lactamases (ESBLs) of the CTX-M type is worrisome issue in many countries of the world from past decade. But little is known about CTX-M beta-lactamase producing bacteria in Pakistan. Therefore, this study was carried out to investigate the distribution of CTX-M beta-lactamase producing E. coli and Klebsiella pneumoniae using phenotypic and molecular techniques. A total of 638 E. coli and 338 Klebsiella pneumoniae were isolated from patients attending two hospitals and one diagnostic Centre in Pakistan during 2013-2015. ESBL production was screened by double disc synergism, combination disc (cefotaxime and ceftazidime with clavulanic acid) and E-test. These strains were further characterized by PCR (CTX-M I, CTX-M III) and sequencing. After ribotyping of strains accession numbers were obtained. These isolates were highly resistant to cephalosporins, ceftazidime, cefotaxime, aztreonam, and cefuroxime but susceptible to carbapenems, sulfzone, amikacin and tazocin. Multiple antibiotic resistances index (MAR) revealed that 51% of E. coli strains fell in the range of 0.61-0.7 and 39% of Klebsiella pneumoniae strains fell in the range of 0.71-0.8. 64% Double disc synergism (DDS), 76.4% combination disc (CD), 74% E-test showed ESBL positivity in strains. In E. coli ESBL genes bla CTX-M-I and bla CTX-M-III were detected in 212 (72.1%) and 25 (8.5%) respectively. In Klebsiella pneumoniae ESBL genes bla CTX-M-I and bla CTX-M-III were detected in 89 (82.4%) and 10 (9.2%). Combination of both genes bla CTX-M-I and bla CTX-M-III were found in 16 (5.4%) of E. coli strains and 5 (4.6%) of Klebsiella pneumoniae strains. Sequencing revealed that CTXM-15 was predominately present in the CTX-M-I group. The prevalence of ESBL producing E. coli and Klebsiella pneumoniae isolates was high and the majority of them positive for bla CTX-M-I as compared to bla CTX-M-III. These findings highlight the need to further investigate the epidemiology of other CTX-M beta-lactamases in Pakistan. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacteriology and Antibiogram of Urinary Tract Infection Among Female Patients in a Tertiary Health Facility in South Eastern Nigeria.

PubMed

Oli, Angus N; Akabueze, Vivian B; Ezeudu, Chijioke E; Eleje, George U; Ejiofor, Obiora S; Ezebialu, Ifeanyichukwu U; Oguejiofor, Charlotte B; Ekejindu, Ifeoma M; Emechebe, George O; Okeke, Kenneth N

2017-01-01

Urinary Tract Infection (UTI) is a common contagion among men and women with the incidence relatively higher among women due to their differing anatomy. An understanding of the kind of pathogens implicated in urinary tract infections as well as antibiotic susceptibility profiling may help the clinician make rationally correct empirical choice in their treatment. This study is aimed at determining the type and antibiotic susceptibility pattern of bacterial uropathogens isolated from female patients attending Chukwuemeka Odumegwu Ojukwu University Teaching Hospital (COOUTH), Awka, Nigeria. Two hundred and forty patients with clinically diagnosed UTI and who were on at least 5 days' antibiotic holiday were recruited into the study. Their demographic characteristics were captured using pre-tested questionnaire. Their clean catch mid-stream urine samples were collected using sterile universal container and sent to the Microbiology Department for processing. Within 30 minutes of samples collection, the specimens were cultured and the isolates were identified, after 24 h of incubation, using standard microbiological techniques. Antibiotic susceptibility tests were done with standard antibiotic discs using the Kirby-bauer disc diffusion method. Out of the 240 urine samples, 89.17% yielded significant bacteriuria. The pathogens implicated were Escherichia coli (28.5%), Staphylococcus aureus (28.0%), Salmonella spp (22.8%) and Pseudomonas aeruginosa (20.5%). HIV status, patients age, pregnancy status and marital status all significantly affected bacteriuria rate (p value < 0.05), while patients' location (sub-urban/rural dwelling), and level of education did not (p value > 0.05). The pattern of microbial resistance to antibiotics suggests that ceftazidime, fosfomycin and cefoxitin may not be used as first-line agents in the empirical treatment of UTIs rather; levofloxacin, meropenem or aztreonam should be considered. Levofloxacin was significantly effective against all the isolates and may be administered empirically while waiting for the culture result (Mean % susceptibility was 79.85). E. coli and S. aureus were the predominant pathogens in the study and many were resistant to the commonly prescribed antibiotics and so leave the clinicians with only few alternative drugs for UTIs treatment. Routine surveillance and monitoring studies need to be constantly conducted to update clinicians on the prevalent pathogens and the rational and empirical treatment of UTIs. Aggressive and consistent health education using every possible media is also recommended to combat the menace of drug resistance occasioned by inappropriate antibiotic use.

Probing the Mechanism of Inactivation of the FOX-4 Cephamycinase by Avibactam.

PubMed

Nukaga, Michiyoshi; Papp-Wallace, Krisztina M; Hoshino, Tyuji; Lefurgy, Scott T; Bethel, Christopher R; Barnes, Melissa D; Zeiser, Elise T; Johnson, J Kristie; Bonomo, Robert A

2018-05-01

Ceftazidime-avibactam is a "second-generation" β-lactam-β-lactamase inhibitor combination that is effective against Enterobacteriaceae expressing class A extended-spectrum β-lactamases, class A carbapenemases, and/or class C cephalosporinases. Knowledge of the interactions of avibactam, a diazabicyclooctane with different β-lactamases, is required to anticipate future resistance threats. FOX family β-lactamases possess unique hydrolytic properties with a broadened substrate profile to include cephamycins, partly as a result of an isoleucine at position 346, instead of the conserved asparagine found in most AmpCs. Interestingly, a single amino acid substitution at N346 in the Citrobacter AmpC is implicated in resistance to the aztreonam-avibactam combination. In order to understand how diverse active-site topologies affect avibactam inhibition, we tested a panel of clinical Enterobacteriaceae isolates producing bla FOX using ceftazidime-avibactam, determined the biochemical parameters for inhibition using the FOX-4 variant, and probed the atomic structure of avibactam with FOX-4. Avibactam restored susceptibility to ceftazidime for most isolates producing bla FOX ; two isolates, one expressing bla FOX-4 and the other producing bla FOX-5 , displayed an MIC of 16 μg/ml for the combination. FOX-4 possessed a k 2 / K value of 1,800 ± 100 M -1 · s -1 and an off rate ( k off ) of 0.0013 ± 0.0003 s -1 Mass spectrometry showed that the FOX-4-avibactam complex did not undergo chemical modification for 24 h. Analysis of the crystal structure of FOX-4 with avibactam at a 1.5-Å resolution revealed a unique characteristic of this AmpC β-lactamase. Unlike in the Pseudomonas -derived cephalosporinase 1 (PDC-1)-avibactam crystal structure, interactions (e.g., hydrogen bonding) between avibactam and position I346 in FOX-4 are not evident. Furthermore, another residue is not observed to be close enough to compensate for the loss of these critical hydrogen-bonding interactions. This observation supports findings from the inhibition analysis of FOX-4; FOX-4 possessed the highest K d (dissociation constant) value (1,600 nM) for avibactam compared to other AmpCs (7 to 660 nM). Medicinal chemists must consider the properties of extended-spectrum AmpCs, such as the FOX β-lactamases, for the design of future diazabicyclooctanes. Copyright © 2018 American Society for Microbiology.

Proposal to rename Carnobacterium inhibens as Carnobacterium inhibens subsp. inhibens subsp. nov. and description of Carnobacterium inhibens subsp. gilichinskyi subsp. nov., a psychrotolerant bacterium isolated from Siberian permafrost.

PubMed

Nicholson, Wayne L; Zhalnina, Kateryna; de Oliveira, Rafael R; Triplett, Eric W

2015-02-01

A novel, psychrotolerant facultative anaerobe, strain WN1359(T), was isolated from a permafrost borehole sample collected at the right bank of the Kolyma River in Siberia, Russia. Gram-positive-staining, non-motile, rod-shaped cells were observed with sizes of 1-2 µm long and 0.4-0.5 µm wide. Growth occurred in the range of pH 5.8-9.0 with optimal growth at pH 7.8-8.6 (pH optimum 8.2). The novel isolate grew at temperatures from 0-37 °C and optimal growth occurred at 25 °C. The novel isolate does not require NaCl; growth was observed between 0 and 8.8 % (1.5 M) NaCl with optimal growth at 0.5 % (w/v) NaCl. The isolate was a catalase-negative, facultatively anaerobic chemo-organoheterotroph that used sugars but not several single amino acids or dipeptides as substrates. The major metabolic end-product was lactic acid in the ratio of 86 % l-lactate : 14 % d-lactate. Strain WN1359(T) was sensitive to ampicillin, chloramphenicol, fusidic acid, lincomycin, monocycline, rifampicin, rifamycin SV, spectinomycin, streptomycin, troleandomycin and vancomycin, and resistant to nalidixic acid and aztreonam. The fatty acid content was predominantly unsaturated (70.2 %), branched-chain unsaturated (11.7 %) and saturated (12.5 %). The DNA G+C content was 35.3 mol% by whole genome sequence analysis. 16S rRNA gene sequence analysis showed 98.7 % sequence identity between strain WN1359(T) and Carnobacterium inhibens. Genome relatedness was computed using both Genome-to-Genome Distance Analysis (GGDA) and Average Nucleotide Identity (ANI), which both strongly supported strain WN1359(T) belonging to the species C. inhibens. On the basis of these results, the permafrost isolate WN1359(T) represents a novel subspecies of C. inhibens, for which the name Carnobacterium inhibens subsp. gilichinskyi subsp. nov. is proposed. The type strain is WN1359(T) ( = ATCC BAA-2557(T) = DSM 27470(T)). The subspecies Carnobacterium inhibens subsp. inhibens subsp. nov. is created automatically. An emended description of C. inhibens is also provided. © 2015 IUMS.

First report in Africa of two clinical isolates of Proteus mirabilis carrying Salmonella genomic island (SGI1) variants, SGI1-PmABB and SGI1-W.

PubMed

Soliman, Ahmed M; Ahmed, Ashraf M; Shimamoto, Toshi; El-Domany, Ramadan A; Nariya, Hirofumi; Shimamoto, Tadashi

2017-07-01

Two Proteus mirabilis strains, designated PmTAN59 and PmKAF126, were isolated from two different Egyptian cities in 2014 and 2015, respectively. PmTAN59 was isolated from a sputum swab from a pneumonia patient in Tanta University Teaching Hospital. PmKAF126 was isolated from a patient with a diabetic foot infection in a hospital in the city of Kafr El-Sheikh. The two isolates were identified with bacterial small ribosomal RNA (16S rRNA) gene amplification and sequencing and tested for antimicrobial sensitivity with a Kirby-Bauer disk diffusion assay. The two strains were resistant to amoxicillin/clavulante, ampicillin, cefotaxime, cefoxitin, ceftriaxone, chloramphenicol, ciprofloxacin, colistin, gentamicin, kanamycin, nalidixic acid, spectinomycin, streptomycin, sulfamethoxazole/trimethoprime, and tetracycline, but sensitive to aztreonam, imipenem, and meropenem. Molecular characterization was used to map the entire backbone, including the multiple antibiotic resistance (MDR) region, of Salmonella genomic island 1 (SGI1). Both isolates carried a structure similar to SGI1, with two different MDR regions corresponding to SGI1-PmABB in PmTAN59 and SGI1-W in PmKAF126. SGI1-PmABB carried an integron of ~1.5kb with a two-gene cassette, aacCA5-aadA7, which confers resistance to gentamicin, streptomycin, and spectinomycin, whereas SGI1-W carried an integron of ~1.9kb containing aadA2-lnuF, which confers resistance to spectinomycin, streptomycin, and lincosamides. PmKAF126 carried the entire SGI1 sequence, however PmTAN59 carried a SGI1 structure with a deletion in the region from ORF S005 to ORF S009 and accompanied by insertion of IS1359 (1258bp). Furthermore, PmTAN59 carried class 2 integron of ~2.2kb containing dfrA1-sat2-aadA1. An ERIC-PCR analysis detected no clonal relationship between the two strains. Molecular screening for other antimicrobial resistance genes and a plasmid analysis indicated that PmTAN59 carried an IncFIB plasmid type. This strain also carried bla TEM-1 and the plasmid-mediated quinolone-resistance gene qnrA1. However, PmKAF126 carried no plasmids and no resistance gene other than that contained in the MDR region of SGI1 and floR gene conferring resistance to florfenicol. To the best of our knowledge, this is the first report of an SGI1-positive P. mirabilis strain in Egypt or on the entire African continent. Copyright © 2017 Elsevier B.V. All rights reserved.

The cost effectiveness of dry powder antibiotics for the treatment of Pseudomonas aeruginosa in patients with cystic fibrosis.

PubMed

Tappenden, Paul; Harnan, Sue; Uttley, Lesley; Mildred, Matthew; Walshaw, Martin; Taylor, Christopher; Brownlee, Keith

2014-02-01

Cystic fibrosis (CF) affects over 9,000 people in the UK and limits life expectancy. CF patients are susceptible to lung infections, most commonly Pseudomonas aeruginosa. Once infection is established, patients require lifetime treatment using nebulised antibiotics. Newer dry powder formulations of antibiotics may reduce treatment burden and improve compliance. Our objective was to evaluate the cost effectiveness of (i) colistimethate sodium dry powder for inhalation (DPI) and (ii) tobramycin DPI versus nebulised tobramycin for the treatment of chronic P. aeruginosa lung infection in patients with CF from the perspective of the National Health Service (NHS) and Personal Social Services (PSS). We developed a state transition model based on transitions between three strata of lung function measured in terms of forced expiratory volume in 1 second (FEV1) % predicted. Additional health states representing post-lung transplantation and dead are also modelled. The model structure was informed by systematic reviews of evidence concerning the plausibility of potential relationships between intermediate endpoints and final outcomes. The model assumes that treatment impacts on FEV1 trajectory, which manifest as changes in health-related quality of life. No survival benefit is assumed due to the absence of robust quantifiable evidence. Model parameters were informed by patient-level and aggregate data from two randomised controlled trials together with the best available evidence from the literature. Resource use and costs associated with drug acquisition, the management of exacerbations and reduced nebuliser maintenance were drawn from reference sources and expert opinion. Costs were valued at 2011/2012 prices. Costs and health outcomes were discounted at a rate of 3.5 %. Simple and probabilistic sensitivity analyses were undertaken, including additional analyses of Patient Access Scheme (PAS) price discounts offered by the manufacturers of both DPI products. Colistimethate sodium DPI is expected to produce fewer quality-adjusted life-years (QALYs) than nebulised tobramycin. Based on its list price, colistimethate sodium DPI is expected to be dominated by nebulised tobramycin. When the PAS is incorporated, the incremental cost-effectiveness ratio (ICER) for colistimethate sodium DPI versus nebulised tobramycin is expected to be approximately £288,600 saved per QALY lost. Based on its current list price, the ICER for tobramycin DPI versus nebulised tobramycin is expected to be approximately £124,000 per QALY gained. When the proposed PAS is included, tobramycin DPI is expected to dominate nebulised tobramycin. Under their list prices, neither DPI product is likely to represent good value for money for the NHS given current cost-effectiveness thresholds. The PAS discounts have a significant impact upon the economic attractiveness of both DPI products compared against nebulised tobramycin. The clinical effectiveness and cost effectiveness of the DPIs against other nebulised antibiotics, such as aztreonam and inhaled colistimethate sodium, remains unclear.

Predominance of carbapenem-resistant Pseudomonas aeruginosa isolates carrying blaIMP and blaVIM metallo-β-lactamases in a major hospital in Costa Rica.

PubMed

Toval, Francisco; Guzmán-Marte, Anel; Madriz, Vivian; Somogyi, Teresita; Rodríguez, César; García, Fernando

2015-01-01

This study aimed to assess the molecular basis of the resistance to carbapenems in clinical isolates of Pseudomonas aeruginosa recovered from a tertiary-level health facility in San José, Costa Rica. A total of 198 non-duplicated isolates were evaluated for their susceptibility to β-lactams, aminoglycosides and fluoroquinolones. The production of metallo-β-lactamases (MBLs), the presence of MBL encoding genes (blaIMP, blaVIM and blaGIM-1) and the occurrence of these genes within class 1 integrons were investigated. In addition, an ERIC2 PCR fingerprinting method was used to elucidate the distribution of the detected MBL genes within the strain collection. Of the 198 isolates tested, 125 (63.1 %) were categorized as carbapenem-resistant. The majority (88.8 %) of the carbapemen-resistant isolates also showed resistance to ceftazidime, cefepime, aztreonam, ticarcillin/clavulanic acid, amikacin, gentamicin, tobramycin, ciprofloxacin and gatifloxacin. Among the carbapenem-resistant isolates, 102 (81.6 %) showed MBL activity. Strikingly, both blaIMP and blaVIM genes were simultaneously detected in most (94.1 %) of the 102 MBL producers. Five carbapenem-resistant MBL producers were positive only for blaIMP genes. Almost 70 % of the isolates examined harboured the intI1 gene, accompanied by the sul1 and qacEΔ1 genes in 136 (99 %) and 122 (89 %) isolates, respectively. The majority (94.4 %) of the carbapenem-resistant isolates carried the intI1 gene, in contrast to 26 % of the carbapenem-susceptible isolates. Ninety-three out of 96 (96.9 %) isolates carrying both blaIMP and blaVIM genes also harboured the intI1, sul1 and qacEΔ1 genes. Gene cassettes from carbapenem-susceptible and MBL-negative carbapenem-resistant isolates encoded aminoglycoside-resistance enzymes (aadA2, aadA4 and aadA6) as well as orfD and qacF genes. RAPD analysis distributed 126 of the isolates in 29 clusters. Eighty of the 90 blaIMP (+) blaVIM (+) isolates were sorted into 16 different clusters, suggesting that the blaIMP and blaVIM genes detected were located within a genetic element capable of lateral transfer. Carbapenem-resistant MBL-positive isolates were recovered from almost all hospital wards and were over-represented in samples obtained from the surgical emergency and intensive care therapy units. Remarkably, three carbapenem-resistant isolates, exhibiting MBL activity and carrying both blaIMP and blaVIM genes, were recovered from outpatients. Sequence analysis of both bla genes in various isolates revealed that they correspond to the alleles blaIMP-18 and blaVIM-2. To our knowledge, this is the first report of the combination of two metallo-β-lactamases encoded by the blaIMP-18 and blaVIM-2 genes in P. aeruginosa. © 2015 The Authors.

Prevalence, antimicrobial resistance and multiple-locus variable-number tandem-repeat analysis profiles of diarrheagenic Escherichia coli isolated from different retail foods.

PubMed

Wang, Lili; Nakamura, Hiromi; Kage-Nakadai, Eriko; Hara-Kudo, Yukiko; Nishikawa, Yoshikazu

2017-05-16

Diarrheagenic E. coli (DEC) isolates were recovered from local retail markets and the Osaka Municipal Central Wholesale Market in Japan. Retail food samples were collected for analysis in Osaka Japan from 2005 to 2008 and consisted of 32 beef, 28 pork, 20 poultry, 136 fish, 66 fruits and vegetables and 51 ready-to-eat (RTE) food samples. A total of 82 DEC strains were recovered from 64 (19%) food samples with the highest prevalence in poultry (100%, 20/20), followed by pork (54%, 15/28), beef (28%, 9/32), fruits and vegetables (12%, 8/66), fish (6.6%, 9/136) and RTE foods (5.9%, 3/51). Most of the strains belonged to E. coli possessing the enteroaggregative E. coli (EAEC) heat-stable enterotoxin 1 (EAST1) gene (EAST1EC; n=62, P<0.0001) and enteropathogenic E. coli (EPEC; n=16, P<0.01), whereas only 1 strain belonged to Shiga toxin-producing E. coli (STEC), 1 to EAEC and 2 to enterotoxigenic E. coli (ETEC) strains. Of the 82 DEC isolates, 22 O and 13H serogroups were detected, including some specific serogroups (O91, O103, O115, O119, O126, and O157) which have been associated with human diarrheal infections. Phylogenetic group A and B1 were predominant among the DEC isolates. Antimicrobial resistance to tetracycline was most common (49%), followed by nalidixic acid (28%), ampicillin (24%), sulfamethoxazole/trimethoprim (20%), and cephalothin (18%). All isolates were susceptible to aztreonam. Of the resistant strains, 44% (22/50) demonstrated resistance to >3 antimicrobial agents. Isolates resistant to >5 antimicrobials were only found in the meat samples, while isolates from the fruits and vegetables as well as RTE foods showed resistance to only 1 or 2 antimicrobial agents. Sixty one percent of EAST1EC, 56% of EPEC and all of the EAEC and ETEC were resistant to at least 1 antimicrobial agent. Multiple-locus variable-number tandem repeat analysis (MLVA) was used in this study for genotyping of DEC. The 82 isolates collected for this study showed 77 distinct MLVA profiles located among 3 branches. The Simpson's Index of Diversity (D) was 99.9% at its highest. The high diversity of these food strains would suggest their originating from a variety of sources and environments. In conclusion, retail food samples in Japan were contaminated with DEC; EAST1EC, a putative DEC, were detected at high rates in poultry, pork and beef. Isolates resistant to >3 antimicrobials were found only in raw meat and fish. Food animals may act as the reservoir for multi-resistant bacteria. Due to the finding that nearly 1/3 of EAST1EC strains were resistant to >3 antimicrobials, additional surveillance for EAST1EC should be initiated. Copyright © 2017 Elsevier B.V. All rights reserved.

SETTING UP OF A HOMECARE SYSTEM FOR HIGH COST NEBULISERS IN A PAEDIATRIC CYSTIC FIBROSIS CENTRE.

PubMed

Chorro-Mari, Veronica; Christiansen, Nanna

2016-09-01

Due to national changes to the commissioning process of high cost nebulisers (HCN) for Cystic Fibrosis (CF) patients, CF centres have to repatriate the prescribing of the HCN to the tertiary care centres.1 The following nebulisers will no longer be prescribed by primary care: Cayston® (Aztreonam); Colomycin®, Pomixin®, Clobreathe® (Colistimethate); Pulmozyme® (Dornase alfa); Tobi®, Tobi Podhaler ®, Bramitob® (Tobramycin).This abstract explains how the Royal London Hospital (RLH) Paediatric Pharmacy recruited over 100 paediatric (CF) patients smoothly within a period of 4 months and set up a homecare system to avoid patients and families having to travel large distances to obtain their medication. A number of homecare companies were evaluated initially. Parameters looked at were reports of customer satisfaction, delivery cost, turn-around time once the prescription was received and availability of same day delivery service.In order to capture existing patients we met with CF Specialist Nurses to establish the total number of patients on HCN, what nebulised treatment they were on and their respective doses. We prioritised patients that had known problems with GP prescribing and anybody newly starting on HCN.To communicate the change to parents, a letter was sent to all parents explaining the changeover to homecare delivery and tertiary prescribing. In addition a section in the parent bulletin was dedicated to the topic as well. Following this we contacted parents via phone and in clinic to request consent and explain the process.Up to 10 patients were contacted weekly (average of 7); the consent form and registration form were then faxed to the Homecare company for patient registration. In parallel to this prescriptions were requested for the patients that had been set up in the previous week, ensuring that prescribing was spread out over time to avoid having peak times for repeat prescriptions.In addition to the letter to parents GP surgeries were also informed in writing about the changes in commissioning and planned repatriation of HCN. This information was also included on discharge prescriptions for patients on any of the HCNs as part of the pharmacy screening process.A system for follow up prescriptions as repeat was set up between the team so we would not have unexpected urgent requests and we could avoid missed doses, urgent delivery charge or stress in the team. In order to manage the prescriptions and ease communication across the team a database was developed. From March to July 2014 (16 weeks) one hundred and four patients were successfully repatriated to tertiary care. A planned method and agreed standard operation procedure was key to effectively capture and repatriate all patients while at the same time keeping the increase on workload for the pharmacy team to a minimum. The fact of having a strong pharmacy presence as part of the multidisciplinary team attending CF clinics and ward rounds was vital in making this work. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

[Evolution of susceptibility to antibiotics of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumanii, in a University Hospital Center of Beirut between 2005 and 2009].

PubMed

Hamouche, E; Sarkis, D K

2012-06-01

Until recently, multiresistant bacteria were only limited to hospitals. However, they are now responsible for community acquired infections, affecting people who have had no contact with the hospital environment. Several mechanisms are associated with these resistances. The production of betalactamases is however the predominant mechanism and especially the production of extended spectrum beta-lactamases or ESBL by strains of Escherichia coli and Klebsiella pneumoniae, which mediate resistance to third generation cephalosporins and aztreonam (AZT). The association of multiple mechanisms of resistance (efflux pumps, impermeability and enzymatic inactivation) generates multi resistant bacteria such as Pseudomonas aeruginosa MDR and Klebsiella pneumoniae MDR. The aim of the study was to analyze retrospectively the susceptibility to antibiotics of strains of E. coli, K. pneumoniae, P. aeruginosa and A. baumanii isolated from hospitalized and outpatients in a university hospital center of Beirut over a period of five years from 2005 to 2009. Bacterial strains were classified according to their origin (inpatients versus outpatients), their ability to produce or not ESBLs for E. coli and K. pneumonia and if they were MDR for P. aeruginosa and A. baumanii. Antibiotics susceptibilities were retrieved from the informatics database of the hospital. Comparison of susceptibility percentages was done using a unilateral z-test on a computer program. In 2009, 2541 strains of E. coli were isolated, 773 of which or 30.4 % were ESBL producers while 2031 strains were isolated in 2005, of which 361 or 17.8 % were ESBL producers (p<0.001). We noticed a decrease in hospital strains susceptibility to ceftazidime (CAZ) and AZT, between 2005 and 2009 (p<0.001), and a decrease in community strains susceptibility to triméthoprime/sulfaméthoxazole (SXT) between 2005 and 2009 (p=0.03). We noted however a significant decrease of ESBL producing strains between 2007 and 2009: 33.4 % versus 30.4 % (p=0.03). Among 560 strains of K. pneumoniae isolated in 2009, 178 strains or 31.8 % were ESBL producers in comparison to 23.7 % of the strains isolated in 2005 (p=0.03). We also noticed a decrease in hospital strains susceptibility to piperacilline-tazobactam (TZP), cefotaxime (CTX) and AZT (p<0.001 p=0.03 and p=0.03 respectively) between 2006 and 2009, and a significant increase in ESBL producing strains between 2008 et 2009 (p=0.0001). 26.5 % of P. aeruginosa strains isolated in 2009 were MDR bacteria with no significant change as compared to 26.6 % in 2005 (p=0.5). However, the percentage of MDR strains slightly decreased between 2008 and 2009 (p=0.047). The susceptibility of MDR strains to CAZ and imipenem (IMP) decreased between 2005 and 2009 (p<0.001 and P=0.003 respectively). As for A. baumanii, 77.7 % of strains were MDR in 2009 in comparison to 73.4 % in 2005 (p=0.24) with a dramatic decrease of MDR strains susceptibility to IMP from 92.3 % in 2006 to 30 % in 2009 (p<0.001). Despite restrictions on antibiotics prescriptions and isolation of patients harboring MDR bacteria or bacteria producing ESBL, there has not been satisfactory reduction of multi resistant bacteria and efforts should be made to reduce these bugs from the hospital flora. Copyright © 2011 Elsevier Masson SAS. All rights reserved.