title: Survey of Salmonella serotypes shed in feces of beef cows and their antimicrobial susceptibility patterns.
abstract: Salmonella prevalence on cow-calf operations was studied 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. Within this study, the prevalence of Salmonella spp. shed in feces was determined. A total of 5,049 fecal samples were collected from 187 beef cow-calf operations each visited on a single occasion. 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 of 187) of the operations. Overall 78 salmonellae representing 22 serotypes were recovered from 1.4% (70 of 5,049) of samples. Multiple serotypes were recovered from eight samples from a single operation. The five most common serotypes were Salmonella Oranienburg (21.8% of isolates), and Salmonella Cerro (21.8%), followed by Salmonella Anatum (10.3%), Salmonella Bredeney (9.0%), and Salmonella 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, 43.6% (34 of 78) and 38.5% (30 of 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 of 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 of 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 (> or =2 antimicrobics) resistance most commonly to streptomycin and sulfamethoxazole (n = 6).
authors.affiliation: US Department of Agriculture-Animal and Plant Health Inspection Service-Veterinary Services (USDA-APHIS-VS), Centers for Epidemiology and Animal Health, Fort Collins, Colorado 80521, USA. David.A.Dargatz@usda.gov
authors.forename: D A
authors.initials: DA
authors.lastname: Dargatz
authors.forename: P J
authors.initials: PJ
authors.lastname: Fedorka-Cray
authors.forename: S R
authors.initials: SR
authors.lastname: Ladely
authors.forename: K E
authors.initials: KE
authors.lastname: Ferris
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D004352:Drug Resistance, Microbial; D005243:Feces / Q000382:microbiology*; D005516:Food Microbiology; D015995:Prevalence; D012475:Salmonella / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D012703:Serotyping; D014481:United States / Q000453:epidemiology