On-farm sources of foodborne pathogens: isolation from the dairy farm environment.

The objective was to determine on-farm sources of Campylobacter jejuni, Salmonella spp., Listeria monocytogenes, and Shiga toxin-producing Escherichia coli (STEC) which might serve as reservoirs for transmission of pathogens. Six visits were made to 4 dairy farms to collect swab, liquid and solid dairy farm environmental samples. Campylobacter jejuni, Salmonella spp., L. monocytogenes, Sorbitol-negative (SN)-STEC O157:H7 and sorbitol-positive (SP)-STEC were isolated from 5.06%, 3.76%, 6.51%, 0.72%, and 17.3%, respectively, of samples evaluated. SN-STEC O157:H7 was isolated from only two farms, whereas other pathogens were isolated from all 4 farms. Diverse serotypes of SP-STEC including O157:H7, O26:H11, O111, and O103 were isolated. None of the five pathogen groups studied were isolated from bulk tank milk (BTM). Most pathogens (44.2%) were isolated directly from fecal samples; bovine fecal samples, lagoon water, and bedding constituted areas of major concern on dairy farms. Although in-line milk filters from two farms tested positive for Salmonella or L. monocytogenes, these pathogens were not detected in the corresponding BTM samples. Good manure management practices are critical in assuring dairy farm hygiene. Identification of on-farm pathogen reservoirs could aid with implementation of farm-specific pathogen reduction programs.