Submitted to: Interscience Conference on Antimicrobial Agents & Chemotherapy Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 8/25/2010
Publication Date: 9/12/2010
Citation: Karlsson, M.S., Howie, R.L., Blickenstaff, K., Ball, T.A., Haro, J.H., Rickert, R., Folster, J., Zhao, S., Cray, P.J., Wichard, J. 2010. Cephalosporin Resistance among Non-Typhi Salmonella from Humans, Retail Meats and Food Animals in the United States. Interscience Conference on Antimicrobial Agents & Chemotherapy Proceedings. Sept. 12-15,2010. Boston, MA. Interpretive Summary:
Technical Abstract: Background: The National Antimicrobial Resistance Monitoring System (NARMS) is a collaboration among the Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA), and the Centers for Disease Control and Prevention (CDC). Here we report on decreased susceptibility to cephalosporins (DSC) among 4,200 non-Typhi Salmonella (NTS) isolated from food animals, retail meats and humans in 2008. Methods: State public health laboratories forwarded NTS from humans to CDC while NTS from retail meat (chicken breasts, ground turkey, ground beef and pork chops) were submitted by 10 states to FDA. Non-Typhi Salmonella from food animals were isolated from cattle, chickens, pigs and turkeys at slaughter and tested at USDA. Minimum inhibitory concentrations (MIC) were determined by broth microdilution. Isolates displaying DSC (ceftriaxone and/or ceftiofur MIC is great than 2mg/L) were included in the study. PCR was used to screen isolates for blaCMY, blaCTX-M, blaTEM, blaSHV and blaOXA-1 genes. Results: Among 2,379 NTS collected from humans, 109 (4.6%) displayed DSC. Among 495 isolates from retail meats and 1,326 isolates from animals, 77 (15.6%) and 140 (10.6%) showed DSC, respectively. A ß-lactamase gene was detected in 74 (67.9%) NTS collected from humans, and blaCMY genes were most prevalent (64.2%). Three isolates from humans harbored a blaCTX-M gene. Among the retail meat and animal NTS, 64 (83.1%) and 138 (98.6%,) respectively, harbored a ß-lactamase gene; 58 retail meat and 138 animal isolates were positive for blaCMY. No animal or retail meat isolates harbored a blaCTX-M, blaSHV or blaOXA-1 gene. A blaTEM gene was found in 5 human, 8 retail and 15 animal isolates. Conclusion: CMY ß-lactamases are the predominant cause of DSC among NTS isolated from humans, retail meats, and food animals in the U.S.