Location: Meat Safety and QualityTitle: The impact of the bovine faecal microbiome on Escherichia coli O157:H7 prevalence and enumeration in naturally infected cattle
|KIM, MINSEOK - Former ARS Employee|
|Bono, James - Jim|
|Kalchayanand, Norasak - Nor|
|BENSON, ANDREW - University Of Nebraska|
|Wells, James - Jim|
Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2017
Publication Date: 9/21/2017
Publication URL: http://handle.nal.usda.gov/10113/5805500
Citation: Kim, M., Kuehn, L.A., Bono, J.L., Berry, E.D., Kalchayanand, N., Freetly, H.C., Benson, A.K., Wells, J. 2017. The impact of the bovine faecal microbiome on Escherichia coli O157:H7 prevalence and enumeration in naturally infected cattle. Journal of Applied Microbiology. 123:1027-1042. https://doi.org/10.1111/jam.13545.
Interpretive Summary: Bacteria are present throughout nature and can have significant impact on biological processes. In animals, the intestinal tract harbors thousands of different bacteria and these microbes can impact health and wellbeing. Escherichia coli O157:H7 is a foodborne pathogen that colonizes the intestinal tract of cattle and other animals and is shed in the feces. In feedlot cattle, diet can affect the shedding of E. coli O157:H7 and the variety of bacteria present in the intestine. The goal of this study was to determine how different diets affect the mix of bacteria in the intestines of cattle and whether any bacteria were associated with the presence of E. coli O157:H7. Across all diets, no single type of intestinal bacteria was associated with E. coli O157:H7 shedding, but within each dietary group there were intestinal bacteria that were correlated with pathogen shedding. Forage based diets exhibited the highest prevalence for E. coli O157:H7 and nearly all the bacteria associated with O157 shedding had positive associations, whereas with a typical high corn diet the E. coli O157:H7 prevalence was lower and most of the bacteria had negative associations. This research has identified a number of bacteria that may be inhibitory to E. coli O157:H7 shedding and additional research is needed to determine the potential mechanisms.
Technical Abstract: Aims: The objective of this study was to determine if the faecal microbiome has an association with Escherichia coli O157:H7 prevalence and enumeration. Methods and Results: Pyrosequencing analysis of faecal microbiome was performed from feedlot cattle fed one of three diets: (i) 94 heifers fed low concentrate (LC) diet, (ii) 142 steers fed moderate concentrate (MC) diet, and (iii) 132 steers fed high concentrate (HC) diet. A total of 322 585 OTUs were calculated from 2,411,122 high-quality sequences obtained from 368 faecal samples. In the LC diet group, OTUs assigned to the orders Clostridiales and RF39 (placed within the class Mollicutes) were positively correlated with both E. coli O157:H7 prevalence and enumeration. In the MC diet group, OTUs assigned to Prevotella copri were positively correlated with both E. coli O157: H7 prevalence and enumeration, whereas OTUs assigned to Prevotella stercorea were negatively correlated with both E. coli O157:H7 prevalence and enumeration. In both the MC diet group and the HC diet group, OTUs assigned to taxa placed within Clostridiales were both positively and negatively correlated with both E. coli O157:H7 prevalence and enumeration. However, all correlations were weak. In both the MC diet group and the HC diet group, stepwise linear regression through backward elimination analyses indicated that these OTUs were significantly correlated (P < 0001) with prevalence or enumeration, explaining as much as 50% of variability in E. coli O157:H7 prevalence or enumeration. Conclusions: Individual colonic bacterial species have little impact on E. coli O157:H7 shedding but collectively groups of bacteria were strongly associated with pathogen shedding. Significance and Impact of the Study: Bacterial groups in the bovine colon may impact faecal shedding of the zoonotic pathogen E. coli O157:H7, and manipulation of the intestinal microbiota to alter these bacteria may reduce shedding of this pathogen and foodborne illnesses.