Submitted to: Salin Pork
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2001
Publication Date: 9/2/2001
Citation: Gray, J.T., Cray, P.J., Haro, J.H., Headrick, M.L. 2001. Expanded-spectrum cephalosporin resistance and multi-drug resistance in salmonella isolates from swine. Salin Pork. P. 377 - 379. Interpretive Summary:
Technical Abstract: We examined a group of cephalosporin resistant isolates from various swine sources submitted to the National Antimicrobial Resistance Monitoring System (NARMS). A total of 50 isolates were obtained between the years 1997 and 1999. Each of the isolates had MIC's to Ceftriaxone, Ceftiofur, and Cephalothin of >/= 32, >/= 64, and >/= 32, respectively. A total of 24 serotypes were identified with no one serotype being predominant. The most common serotypes were Agona (8), Derby (6), typhimurium-copenhagen (4), and Heidelberg (4). Isolates were obtained from diagnostic laboratories (29) federally inspected slaughter and processing plants (18) as well as on farm swine surveys (1). Interestingly, the majority of these isolates were found to be resistant to 8 or more of 17 antimicrobials and 44% of the isolates were resistant to 10 or more antimicrobials as compared to 0.8% of the general population of Salmonella isolates tested (2391) having resistance to 10 or more antimicrobials in 1997. Seventy-four percent (37) of the isolates were resistant to amoxicillin-clavulanic acid. The most common non beta-lactam resistances were streptomycin, kanamycin, sulfamethoxasole, chloramphenicol and gentamicin. A subset of isolates was examined for cephalosporin resistance mechanisms; 19 of 22 isolates were found to have an AmpC like beta lactamase and tested positive for the cmy-2 gene by PCR and two of the isolates had a putative ESBL. Resistance of Salmonella strains to 3rd generation cephalosporins is a concern and these analyses indicate the predilection of these strains to acquire multiple antimicrobial resistances.