Serotyping and antibiotic resistance profiling of Salmonella in feedlot and nonfeedlot beef cattle.
As part of a larger study to assess risk factors associated with hide and carcass contamination of beef cattle during transport to slaughter, a total of 281 salmonellae were isolated from 1,050 rectal, hide, carcass, and environmental samples. For feedlot cattle, salmonellae were recovered from 4.0% of rectal samples, 37.5% of hide samples, 19.0% of carcass samples, and 47.4% of environmental samples. For nonfeedlot cattle, salmonellae were recovered from 10.9% of rectal samples, 37.5% of hide samples, 54.2% of carcass samples, and 50.0% of environmental samples. Overall, the five serotypes most commonly associated with feedlot cattle and their environment were Salmonella Anatum (18.3% of the isolates), Salmonella Kentucky (17.5%), Salmonella Montevideo (9.2%), Salmonella Senftenberg (8.3%), and Salmonella Mbandaka (7.5%). The five serotypes most commonly associated with nonfeedlot cattle and their environment were Salmonella Kentucky (35.4%), Salmonella Montevideo (21.7%). Salmonella Cerro (7.5%), Salmonella Anatum (6.8%), and Salmonella Mbandaka (5.0%). Antimicrobial susceptibility testing of all of the isolates associated with feedlot cattle revealed that 21.7% were resistant to tetracycline, compared with 11.2% of the isolates associated with nonfeedlot cattle. None of the other isolates from feedlot cattle were resistant to any of other antimicrobial agents tested, whereas 6.2% of nonfeedlot cattle isolates were resistant to more than four of the antimicrobial agents tested.
Beach
John C
JC
Department of Animal Science, Texas A&M University, College Station 77843-2471, USA.
Murano
Elsa A
EA
Acuff
Gary R
GR
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D005506:Food Contamination; D005516:Food Microbiology; D008826:Microbial Sensitivity Tests; D012475:Salmonella / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification; D012703:Serotyping
D000900:Anti-Bacterial Agents