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Title: SURVEY OF SALMONELLA SEROTYPES SHED IN FECES OF BEEF COWS AND THEIR ANTIMICROBIAL SUSCEPTIBILITY PATTERNS

Author
item DARGATZ, D - USDA-APHIS
item Cray, Paula
item Ladely, Scott
item FERRIS, K - USDA-APHIS

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2000
Publication Date: 8/24/2000
Citation: Dargatz, D.A., Cray, P.J., Ladely, S.R., Ferris, K.E. 2000. Survey of salmonella serotypes shed in feces of beef cows and their antimicrobial susceptibility patterns. Journal of Food Protection. Vol. 63. No. 12. P. 1648-1653.

Interpretive Summary: Salmonellae are ubiquitous in nature and have been associated with both animal disease and human food borne infections. However, the prevalence among food animals appears to change over time. In this study, we determined the prevalence of Salmonella species shed in the feces of cow/calf operations in the US. A total of 5049 fecal samples were collected from 187 beef co-calf operations and cultured for Salmonella. I addition, we determined the antimicrobial resistance profile for each of the Salmonella isolates that were isolated. Overall, the prevalence was 1.4% (70/5049) and 21 of 187 (11.2%) of the operations were positive for Salmonella. More than one type of Salmonella was recovered from eight samples. Of the 78 Salmonella isolates, 68 (87.2%) were susceptible to all of the antimicrobials that were tested. Only nine isolates were resistant to two or more antimicrobials. These data indicate that the prevalence of and resistance to antimicrobials among Salmonella isolates recovered from cow/calf operations is low. This information is important for the industry as they develop ways to reduce Salmonella among the cow/calf operations. It is also important for veterinarians to know which drugs are effective when animals require treatment.

Technical Abstract: Salmonella prevalence on cow/calf operations was studies as a part of a national study of health and management of the U.S. beef cow/calf industry and was conducted as part of the National Animal Health Monitoring System (NAHMS). Within this study, the prevalence of Salmonella species (spp.) shed in feces was determined. A total of 5049 fecal samples were collected from 187 beef cow-calf operations. The number of fecal samples collected per operation was predetermined based on herd size. Salmonellae were recovered from 1 or more fecal samples collected on 11.2% (21/187) of the operations. Overall 78 salmonellae representing 22 serotypes were recovered from 1.4% (70/5049) of samples. Multiple serotypes were recovered from eight samples from a single operation. The five most common serotypes were S. Oranienburg (21.5% of isolates), and S. Cerro (21.5%), followed by S. Anatum (10.3%), S. Bredeney (9.0%) and S. Mbandaka (5.1%). The most common serogroups identified were C1 (33.3%), K (21.8%), B (16.7%), and E (15.4%). Even though the recovery rate of salmonellae from fecal samples was very low, 43.5% (34/78) and 38.5% (30/78) of the isolates were among the 10 most common serotypes from cattle with clinical signs of disease or isolated from humans, respectively. The majority of the isolates (50/78; 64.1%) were recovered from fecal samples from two operations. All isolates were screened for resistance to a panel of 17 antimicrobics and 87.2% (68/78) were susceptible to all of the antimicrobics. The resistant isolates were most commonly resistant to streptomycin (n=9) and/or sulfamethoxazole (n=9). Nine isolates showed multiple (>/=2 antimicrobics) resistance most commonly to streptomycin and sulfamethoxazole (n=6).