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Applied and Environmental Microbiology, October 2009, p. 6515-6523, Vol. 75, No. 20
0099-2240/09/$08.00+0 doi:10.1128/AEM.00081-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Longitudinal Study of Escherichia coli O157:H7 in a Beef Cattle Feedlot and Role of High-Level Shedders in Hide Contamination
Terrance M. Arthur,1*
James E. Keen,1,2
Joseph M. Bosilevac,1
Dayna M. Brichta-Harhay,1
Norasak Kalchayanand,1
Steven D. Shackelford,1
Tommy L. Wheeler,1
Xiangwu Nou,1,
and
Mohammad Koohmaraie1,
U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Nebraska 68933-0166,1 University of Nebraska—Lincoln, Department of Veterinary and Biomedical Sciences, Great Plains Veterinary Educational Center, Clay Center, Nebraska 689332
Received 13 January 2009/ Accepted 8 August 2009
The objectives of the study described here were (i) to investigate the dynamics of Escherichia coli O157:H7 fecal and hide prevalence over a 9-month period in a feedlot setting and (ii) to determine how animals shedding E. coli O157:H7 at high levels affect the prevalence and levels of E. coli O157:H7 on the hides of other animals in the same pen. Cattle (n = 319) were distributed in 10 adjacent pens, and fecal and hide levels of E. coli O157:H7 were monitored. When the fecal pen prevalence exceeded 20%, the hide pen prevalence was usually (25 of 27 pens) greater than 80%. Sixteen of 19 (84.2%) supershedder (>104 CFU/g) pens had a fecal prevalence greater than 20%. Significant associations with hide and high-level hide (
40 CFU/100 cm2) contamination were identified for (i) a fecal prevalence greater than 20%, (ii) the presence of one or more high-density shedders (200 CFU/g) in a pen, and (iii) the presence of one or more supershedders in a pen. The results presented here suggest that the E. coli O157:H7 fecal prevalence should be reduced below 20% and the levels of shedding should be kept below 200 CFU/g to minimize the contamination of cattle hides. Also, large and unpredictable fluctuations within and between pens in both fecal and hide prevalence of E. coli O157:H7 were detected and should be used as a guide when preharvest studies, particularly preharvest intervention studies, are designed.
* Corresponding author. Mailing address: Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933-0166. Phone: (402) 762-4227. Fax: (402) 762-4149. E-mail: terrance.arthur{at}ars.usda.gov
Published ahead of print on 14 August 2009.
Present address: USDA, ARS, Animal & Natural Resource Institute, Building 201, BARC-East, 10300 Baltimore Ave., Beltsville, MD 20705-2350.
Present address: IEH Laboratories and Consulting Group, 15300 Bothell Way NE, Lake Forest Park, WA 98155.
Applied and Environmental Microbiology, October 2009, p. 6515-6523, Vol. 75, No. 20
0099-2240/09/$08.00+0 doi:10.1128/AEM.00081-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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