Horizontal Transmission of Escherichia coli O157:H7 during Cattle Housing

Abstract

Ruminant livestock, particularly cattle, is considered the primary reservoir of Escherichia coli O157:H7. This study examines the transmission of E. coli O157:H7 within groups of cattle during winter housing. Holstein Friesian steers were grouped in six pens of five animals. An animal inoculated with and proven to be shedding a marked strain of E. coli O157: H7 was introduced into each pen. Fecal (rectal swabs) and hide samples (900 cm2 from the right rump) were taken from the 36 animals throughout the study. Water, feed, and gate or partition samples from each pen were also examined. Within 24 h of introducing the inoculated animals into the pens, samples collected from the drinking water, pen barriers, and animal hides were positive for the pathogen. Within 48 h, the hides of 20 (66%) of 30 cohort animals from the six pens were contaminated with E. coli O157:H7. The first positive fecal samples from the noninoculated cohort animals were detected 3 days after the introduction of the inoculated steers. During the 23 days of the study, 15 of 30 cohort animals shed the marked E. coli O157:H7 strain in their feces on at least one occasion. Animal behavior in the pens was monitored during a 12-h period using closed circuit television cameras. The camera footage showed an average of 13 instances of animal grooming in each pen per hour. The study suggests that transmission of E. coli O157:H7 between animals may occur following ingestion of the pathogen at low levels and that animal hide may be an important source of transmission.

Longitudinal Study of Escherichia coli O157:H7 in a Beef Cattle Feedlot and Role of High-Level Shedders in Hide Contamination

“…Overall, the pens receiving the high-level-inoculum fecal pats had the highest hide prevalence (3%); for the low-level-inoculum pens there was only one positive hide sample (0.45%), and for the control pens there was no positive hide sample (28). Similar findings were obtained by McGee et al (21) when inoculated steers, each shedding E. coli O157:H7 at levels greater than 500 CFU/g of feces, were placed in pens with five uninoculated, noncolonized cohorts. Hide samples from 66% of the cohort animals were found to be positive for the marked strains after 48 h of exposure to the high-level-shedding animals (21).…”

“…Similar findings were obtained by McGee et al (21) when inoculated steers, each shedding E. coli O157:H7 at levels greater than 500 CFU/g of feces, were placed in pens with five uninoculated, noncolonized cohorts. Hide samples from 66% of the cohort animals were found to be positive for the marked strains after 48 h of exposure to the high-level-shedding animals (21). In one pen all of the occupants (the inoculated animal and the five cohorts) harbored E. coli O157:H7 on their hides within 24 h of comingling (21).…”

“…Hide samples from 66% of the cohort animals were found to be positive for the marked strains after 48 h of exposure to the high-level-shedding animals (21). In one pen all of the occupants (the inoculated animal and the five cohorts) harbored E. coli O157:H7 on their hides within 24 h of comingling (21). In the current study, pulsed-field gel electrophoresis was per- formed with all E. coli O157:H7 isolates in an attempt to attribute hide contamination to the animals shedding high levels of bacteria.…”

Transportation and Lairage Environment Effects on Prevalence, Numbers, and Diversity of Escherichia coli O157:H7 on Hides and Carcasses of Beef Cattle at Processing

“…In the current study, a small number of the cattle shedding E. coli O157:H7 (8.6% in group 1) can lead to dramatic increases in hide prevalence and counts (from 28 to 89% and from 6 to 16 animals with high hide numbers) in a very short period (Table 1). McGee et al (19) found that within 24 h of introducing animals known to be shedding E. coli O157:H7 the hides of cohort animals became contaminated, and at 48 h 66% of the penmates had E. coli O157:H7 on their hides. In another study performed using molecular tracking methods, direct hide-to-hide contamination was a viable route for the transmission of E. coli O157:H7 during transport and lairage (27).…”

In Vivo and Ex Vivo Evaluations of Bacteriophages e11/2 and e4/1c for Use in the Control of Escherichia coli O157:H7

“…Ideally, the reduction of the pathogen load in the animals would potentially reduce food-borne illness risk without a reduction in prevalence of the organism (7). E. coli O157:H7 is easily transferred between animals and their surrounding environments (21,34). Sources such as water, soil, and manure can be long-term reservoirs for E. coli O157:H7, and reinfection can occur.…”