Search Results

Abstract

Objective—To describe the frequency and distribution of Escherichia coli O157:H7 in the feces and environment of cow-calf herds housed on pasture.

Sample Population—Fecal and water samples for 10 cow-calf farms in Kansas.

Procedure—Fecal and water samples were obtained monthly throughout a 1-year period (3,152 fecal samples from 2,058 cattle; 199 water samples). Escherichia coli O157:H7 in fecal and water samples was determined, using microbial culture.

Results—Escherichia coli O157:H7 was detected in 40 of 3,152 (1.3%) fecal samples, and 40 of 2,058 (1.9%) cattle had ≥ 1 sample with E coli. Fecal shedding by specific cattle was transient; none of the cattle had E coli in more than 1 sample. Significant differences were not detected in overall prevalence among farms. However, significant differences were detected in prevalence among sample collection dates. Escherichia coli O157:H7 was detected in 3 of 199 (1.5%) water samples.

Conclusions and Clinical Relevance—Implementing control strategies for E coli O157:H7 at all levels of the cattle industry will decrease the risk of this organism entering the human food chain. Devising effective on-farm strategies to control E coli O157:H7 in cow-calf herds will require an understanding of the epidemiologic characteristics of this pathogen. (Am J Vet Res 2000;61:1375–1379)

Abstract

Objective—To determine the diversity of Salmonella serotypes isolated from a large population of cull (market) dairy cows at slaughter.

Design—Cross-sectional study.

Sample Population—Salmonella organisms isolated from the cecal-colon contents of 5,087 market dairy cows.

Procedure—During winter and summer 1996, cecalcolon contents of cull dairy cows at slaughter were obtained from 5 US slaughter establishments. Specimens were subjected to microbiologic culturing for Salmonella spp at 1 laboratory. Identified isolates were compared with Salmonella isolation lists published by the Centers for Disease Control and Prevention (CDC) and the National Veterinary Services Laboratory (NVSL) for approximately the same period. The Simpson diversity index was used to calculate the likelihood that Salmonella isolates selected randomly by establishment were different.

Results—Of 58 Salmonella serotypes identified, Salmonella ser. Montevideo was the most prevalent. Two of the top 10 CDC serotypes identified from humans in 1996, Salmonella ser. Typhimurium and S Montevideo, appeared on our top 10 list; 8 of the top 10 were found on NVSL listings. Thirty-one of 59 S Typhimurium isolates were identified as DT104 and found at a west slaughter establishment, 30 during the winter and 1 during the summer. The greatest diversity of serotypes was at a southeast establishment during the summer; the least diversity was at a central establishment in the winter.

Conclusions and Clinical Relevance—58 Salmonella serotypes were isolated from market dairy cows at slaughter and could pose a threat for food-borne illness. Salmonella Montevideo was the most frequently isolated serotype and may contribute substantially to salmonellosis in dairy cattle. (J Am Vet Med Assoc 2001;219:1216–1220)

Abstract

Objective—To determine the prevalence of Salmonella spp in the cecal-colon contents of cull (market) dairy cows at slaughter because of potential public health ramifications.

Design—Survey study.

Sample Population—Cecal-colon contents collected from 5,087 cull (market) dairy cows at slaughter at 5 slaughter establishments across the United States.

Procedure—During 2 periods of the year, winter (January and February) and summer (July through September), 5 cull (market) cow slaughter establishments in the United States—west (WE), southeast (SEE), central (CE), north central (NCE), and south central (SCE)—establishments were visited, and cecalcolon contents of cull dairy cows were obtained at the time of slaughter. Samples were examined by microbiologic culture at a single laboratory for Salmonella spp.

Results—Salmonella spp were detected in 23.1% of cecal-colon content samples from cull dairy cows across the 5 slaughter establishments. The highest site prevalence (54.5%) was detected at the WE during the summer period, whereas the lowest was found at the CE during the summer (4.3%) and at the NCE during the winter (4.5%). Considerable variation in the daily prevalence of Salmonella spp was found, particularly at the WE and the SCE. Salmonella spp were isolated from 93% of cecal-colon contents collected on a summer day at the WE.

Conclusions and Clinical Relevance—Results strongly suggest that there is a high prevalence of Salmonella spp in cull dairy cows at slaughter, which could burden Hazard Analysis Critical Control Point programs implemented in slaughter establishments. Procedures to reduce Salmonella load at the dairy farm and during transport to slaughter could reduce the risk of spread during the slaughter process. (J Am Vet Med Assoc 2001;219:1212–1215)