Food Safety: Poultry Aspects

Super-shedders, cattle shedding at least 104 colony forming units (CFU) of E. coli O157:H7, elevate risks of contaminating the food chain and maintaining the organism in cattle populations. As detecting supershedders in cattle populations is laborious and time-consuming, a study was conducted to evaluate the role of hide and pen-floor contamination by model super shedders (MSS) in transmission of E. coli O157:H7 to penned cattle. Steers (n = 48) negative for E. coli O157:H7 for 3 wks were allocated to 6 pens, with 2 replicate pens per treatment. Treatment A consisted of 3000 g of feces inoculated with 106 CFU spread in artificial fecal pats on the pen floor for d 0 through 4 and 14 through 18 of the study. For treatment B, 100 g of the feces was spread on the perineum of 1 MSS per pen and the remaining feces spread on the pen floor similar to treatment A. Treatment C differed from B in that 50 g of feces was spread on the perineum and 50 g on the brisket of the MSS. Fecal samples, perineal swabs (500 cm2 area of the rump), freshly voided fecal pats and manila rope samples were collected during the 56 d experimental period. More positive rope samples were found in treatments B and C as compared with A (P < 0.05) and steers within treatments B and C were 1.3 times more likely (P < 0.05) to shed E. coli O157:H7 in their feces than steers in treatment A. Even though loads of E. coli O157:H7 were similar in pens, results indicate a heightened importance of hide as compared with pen floor contamination for transmission of this organism to cattle. As cattle within treatments B and C were persistently colonized with E. coli O157:H7, this model would be suitable for future studies investigating mitigation of E. coli O157:H7 transmission by super-shedders.