Dataset Information

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.

ABSTRACT: 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.

SUBMITTER: Zhao S

PROVIDER: S-EPMC2794113 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

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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.

Zhao S S Blickenstaff K K Glenn A A Ayers S L SL Friedman S L SL Abbott J W JW McDermott P F PF

Applied and environmental microbiology 20091023 24

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 ...[more]

PMID: 19854922

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Project description:Bacteria of the genus Enterococcus are important human pathogens that are frequently resistant to a number of clinically important antibiotics. They are also used as markers of animal fecal contamination of human foods and are employed as sentinel organisms for tracking trends in resistance to antimicrobials with Gram-positive activity. As part of the National Antimicrobial Resistance Monitoring System (NARMS), we evaluated several retail meat commodities for the presence of enterococci from 2002 to 2014, and we found 92.0% to be contaminated. The majority of isolates were either Enterococcus faecalis (64.0%) or Enterococcus faecium (28.6%), and the antimicrobial resistance of each isolate was assessed by broth microdilution. The resistance prevalences for several drugs, including erythromycin and gentamicin, were significantly higher among poultry isolates, compared to retail beef or pork isolates. None of the isolates was resistant to the clinically important human drug vancomycin, only 1 isolate was resistant to linezolid, and resistance to tigecycline was below 1%. In contrast, a majority of both E. faecalis (67.5%) and E. faecium (53.7%) isolates were resistant to tetracycline. Overall, the robust NARMS testing system employed consistent sampling practices and methods throughout the testing period, with the only significant trend in resistance prevalence being decreased E. faecium resistance to penicillin. These data provide excellent baseline levels of resistance that can be used to measure future changes in resistance prevalence that may result from alterations in the use of antimicrobials in food animal production.IMPORTANCE Enterococci, including E. faecalis and E. faecium, are present in the guts of food-producing animals and are used as a measure of fecal contamination of meat. We used the large consistent sampling methods of NARMS to assess the prevalence of Enterococcus strains isolated from retail meats, and we found over 90% of meats to be contaminated with enterococci. We also assessed the resistance of the Enterococcus strains, commonly used as a measure of resistance to agents with Gram-positive activity, in foods. Resistance prevalence was over 25% for some antimicrobials and sample sources but was less than 1% for several of the most important therapeutic agents used in human medicine.

Project description:A total of 133 Salmonella isolates recovered from retail meats purchased in the United States and the People's Republic of China were assayed for antimicrobial susceptibility, the presence of integrons and antimicrobial resistance genes, and horizontal transfer of characterized antimicrobial resistance determinants via conjugation. Seventy-three (82%) of these Salmonella isolates were resistant to at least one antimicrobial agent. Resistance to the following antibiotics was common among the United States isolates: tetracycline (68% of the isolates were resistant), streptomycin (61%), sulfamethoxazole (42%), and ampicillin (29%). Eight Salmonella isolates (6%) were resistant to ceftriaxone. Fourteen isolates (11%) from the People's Republic of China were resistant to nalidixic acid and displayed decreased susceptibility to ciprofloxacin. A total of 19 different antimicrobial resistance genes were identified in 30 multidrug-resistant Salmonella isolates. The bla(CMY-2) gene, encoding a class A AmpC beta-lactamase, was detected in all 10 Salmonella isolates resistant to extended-spectrum beta-lactams. Resistance to ampicillin was most often associated with a TEM-1 family beta-lactamase gene. Six aminoglycoside resistance genes, aadA1, aadA2, aacC2, Kn, aph(3)-IIa, and aac(3)-IVa, were commonly present in the Salmonella isolates. Sixteen (54%) of 30 Salmonella isolates tested had integrons ranging in size from 0.75 to 2.7 kb. Conjugation studies demonstrated that there was plasmid-mediated transfer of genes encoding CMY-2 and TEM-1-like beta-lactamases. These data indicate that Salmonella isolates recovered from retail raw meats are commonly resistant to multiple antimicrobials, including those used for treating salmonellosis, such as ceftriaxone. Genes conferring antimicrobial resistance in Salmonella are often carried on integrons and plasmids and could be transmitted through conjugation. These mobile DNA elements have likely played an important role in transmission and dissemination of antimicrobial resistance determinants among Salmonella strains.

Dataset Information

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.

Publications

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.

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