Probiotics are not just consumed by people. Probiotics are used for pets (cats and dogs), horses, fish and livestock. A new paper evaluated the state of the science regarding the ability of probiotics to reduce shedding of pathogens – specifically E. coli O157 – in cattle (Wisener 2014). Reducing pathogen shedding in animals that are destined to become human food is likely to result in a safer food supply. (Note that although the term ‘probiotic’ encompasses use of live microorganisms for any host species, in the United Sates probiotics used in animals are called ‘direct fed microbials.’)(U.S. Food and Drug Administration, 2009)
Facts about E. coli 0157:
- It is the most common strain of Shiga-toxin producing E. coli associated with human infections
- It does not cause disease in the carrier animal
- It causes bloody diarrhea and hemolytic uremic syndrome, a leading cause of acute renal failure in children
- It is transmitted through foods, drinking or recreational water, contact with farm animals and person-to-person
- Internationally, beef products are associated with 44% of food-borne E. coli 0157 outbreaks
Wisener et al. (2014) conducted a systematic review and meta-analysis on the efficacy of probiotics compared to a control to reduce pre-harvest fecal shedding of E. coli O157 from the environment in beef cattle. Sixteen studies (through September 2012) were included in the review. Two different endpoints were evaluated: (1) Presence or absence of fecal shedding/colonization of E. coli O157 at the end of the trial or (2) Presence or absence of shedding of E. coli O157 over the entire trial period. One limitation of this review is that it was limited to prevalence (presence or absence), not concentration (numbers of E. coli). Authors also considered whether type of probiotic or duration of feeding (<90 days or >= 90 days) were important factors. The most common probiotic product used in the studies was a commercial product named “Bovamine”, which contains Lactobacillus acidophilus (NP51) and Propionibacterium freudenreichii (NP24).
The main conclusion from the review was that probiotics could reduce E. coli shedding in feedlot beef cattle, both at time of harvest and throughout the feeding period. Reduced shedding at time of harvest is likely important to reducing the risk of food contamination, whereas reduced shedding throughout the feeding period is important to reduced risk of environmental contamination. This finding has important public health implications for use of probiotics in food animals.
Wisener L.V. Sargeant J.M. O’Connor A.M. Faires M.C. Glass-Kaastra S.K. 2014. The use of direct-fed microbials to reduce shedding of Escherichia coli O157 in beef cattle: A systematic review and meta-analysis. Zoonoses and Public Health. doi: 10.1111/zph.12112.
U.S. Food and Drug Administration, CPG Sec.689.100 Direct-Fed Microbial Products, 2009