Persistence of Escherichia coli O157[ratio ]H7 in dairy cattle and the dairy farm environment

Abstract

The persistence of Escherichia coli O157:H7 in cattle and the farm environment was investigated on eight Ontario dairy farms positive for E. coli O157:H7 in a longitudinal study commenced one year previously. Faecal samples from cows, calves, humans, cats, rodents, wild birds, a composite fly sample and numerous composite and individual environmental samples were cultured and tested for verotoxin-producing E. coli (VTEC). VTEC isolates were serotyped and E. coli O157:H7 isolates were phage typed. E. coli O157:H7 phage type 34 was isolated from one calf on each of two farms. The same phage type had been isolated on one of these farms 12 months earlier. Most E. coli O157:H7-positive animals and farms became culture-negative within 2 and 3 months, respectively. E. coli O157:H7 was not isolated from any environmental samples, although evidence of VTEC was found in composite samples from calf feeders (19.1%), calf barn surfaces (18%), cow feeders (14.9%), flies (12.5%), cow barn surfaces (11.3%), and individual milk filters (12.5%). VTEC belonging to 21 non-O157 serotypes were isolated from 24 cows (8.2%), 21 calves (18.3%), 2 cow feeder samples (3.0%), and 1 calf feeder sample (4.8%). Shedding of E. coli O157:H7 by infected dairy cattle appears to be transient and persistence of E. coli O157:H7 was not demonstrated from the farm environment sites tested.

Shigatoxigenic Escherichia coli serogroups O157, O111 and O113 in feces, water and milk samples from dairy farms

“…1). These findings agree with data reported by Blanco et al Efforts should be focused on infection control in order to reduce the prevalence of such microorganisms (40). According to Kudva et al (28), Escherichia coli O157 may survive at least six weeks in feces and possibly multiply in this material.…”

“…These include stress prevention, controlling food and water quality, as well as feedlot conditions and contact between adult and young animals (40).…”

Persistence of Escherichia coli O157 Isolates on Bovine Farms in England and Wales

“…However, it also seems true that individual animals may shed multiple strains simultaneously, and the spectrum of types changes over time (7). Some studies have indicated that E. coli O157 strains seem to be continually replaced by new and distinct types in cattle (4,13). This agrees with the results in our study, where on several occasions, animals appeared to shed different types at different times.…”

A Three-Year Study of Enterohemorrhagic Escherichia coli O157 on a Farm in Japan

“…Cooked ground beef, cow milk, dairy products, and so on are thought to be the major sources of EHEC infection [4,26,27], and cattle and other ruminants, such as sheep and goats, are known to harbor the organisms in their faeces and are regarded as natural reservoirs of the organisms [2,3,5,22,25]. The prevalence of EHEC O157 in cattle has been reported to be 0.2-60.4% in the United States [10,13,23,28], 1.9% in Australia [7], and 4.2-66.7% in Europe [5,6,16,24].…”