|Farrington, L - TEXAS A&M UNIVERSITY|
|Inskip, P - TEXAS A&M UNIVERSITY|
Submitted to: International Symposium on Epidemiology and Control of Salmonella in Pork
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 1999
Publication Date: N/A
Technical Abstract: We conducted a survey of antibiotic resistance in Salmonella isolated from market-age swine at five different farms. Samples were taken from the lymph nodes and cecal contents at the time of slaughter. Of the 559 Salmonella isolates recovered, 420 were sent to the National Veterinary Services Laboratory for serotyping. Resistance patterns were determined by disk diffusion using thirteen antibiotics, and 320 isolates were analyzed. Resistance was observed to ampicillin, chloramphenicol, chlortetracycline, nitrofurantoin, penicillin G, streptomycin and sulfisoxazole. Multi-drug resistance (resistance to two or more antibiotics) was observed in 183 isolates (57.2%) with 34 of these isolates (18.6%) resistant to three antibiotics and 26 (8.1%) resistant to four antibiotics. The most common three drugs resistance pattern consisted of chlortetracycline, penicillin G and streptomycin (37.3%). A significant difference was observed between serotypes and between somatic serogroups in their antibiotic resistance patterns. Variation also was observed between farms and between seasons in which sampling occurred. As a step in understanding the connection between antibiotic use in agriculture and medicine and emergence of antibiotic resistant bacteria, programs that monitor the levels of antibiotic resistance must be continued. In animal production, where sub-therapeutic administration of antibiotics is extremely common, continued surveillance is especially important.