Longitudinal study of Escherichia coli O157:H7 dissemination on four dairy farms in Wisconsin

• Published in: Applied and environmental microbiology 1998-04, Vol.64 (4), p.1390-1399
• Main Authors: Shere, J.A. (University of Wisconsin, Madison, WI.), Bartlett, K.J, Kaspar, C.W
• Format: Article
• Language: English
• Subjects: Animal Husbandry; Animals; Bacteria; Bacteriology; Biological and medical sciences; Cattle; Cattle - microbiology; DAIRY FARMS; Dairying; Disease Reservoirs; DNA, Bacterial - genetics; DNA, Bacterial - isolation & purification; Drug Resistance, Microbial; Environmental and Public Health Microbiology; Epidemiology; ESCHERICHIA COLI; Escherichia coli O157 - genetics; Escherichia coli O157 - isolation & purification; Escherichia coli O157 - pathogenicity; EXPLOITATION LAITIERE; Farms; Female; Food Microbiology; Fundamental and applied biological sciences. Psychology; GRANJAS LECHERAS; Longitudinal Studies; Male; Microbiology; Phenotype; Water Microbiology; WISCONSIN
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.64.4.1390-1399.1998

A 14-month longitudinal study was conducted on four dairy farms (C, H, R, and X) in Wisconsin to ascertain the source(s) and dissemination of Escherichia coli O157:H7. A cohort of 15 heifer calves from each farm were sampled weekly by digital rectal retrieval from birth to a minimum of 7 months of age (range, 7 to 13 months). Over the 14 months of the study, the cohort heifers and other randomly selected cattle from farms C and H tested negative. Farm R had two separate periods of E. coli O157:H7 shedding lasting 4 months (November 1995 to February 1996) and 1 month (July to August 1996), while farm X had at least one positive cohort animal for a 5-month period (May to October 1996). Heifers shed O157:H7 strains in feces for 1 to 16 weeks at levels ranging from 2.0 x 10(2) to 8.7 x 10(4) CFU per g. E. coli O157:H7 was also isolated from other noncohort cattle, feed, flies, a pigeon, and water associated with the cohort heifers on farms R and/or X. When present in animal drinking water, E. coli O157:H7 disseminated through the cohort cattle and other cattle that used the water source. E. coli O157:H7 was found in water at 1 to 23 CFU/ml. Genomic subtyping by pulsed-field gel electrophoresis demonstrated that a single O157:H7 strain comprised a majority of the isolates from cohort and noncohort cattle, water, and other positive samples (i.e., from feed, flies, and a pigeon, etc.) on a farm. The isolates from farm R displayed two predominant XbaI restriction endonuclease digestion profiles (REDP), REDP 3 and REDP 7, during the first and second periods of shedding, respectively. Six additional REDP that were greater than or equal to 89% similar to REDP 3 or REDP 7 were identified among the farm R isolates. Additionally, the REDP of an O157:H7 isolate from a heifer on farm R in 1994 was indistinguishable from REDP 3. Farm X had one O157:H7 strain that predominated (96% of positive samples had strains with REDP 9)