Interactions of the hindgut mucosa-associated microbiome with its host regulate shedding of Escherichia coli O157: H7 by cattle


Wang, O., McAllister, T.A., Plastow, G., Stanford, K., Selinger, B., Guan, L.L. (2018). Interactions of the hindgut mucosa-associated microbiome with its host regulate shedding of Escherichia coli O157: H7 by cattle, 84(1),

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Cattle with high levels of the pathogen E. coli O157:H7 within their feces have been defined as supershedders, and they are responsible for the most of the E. coli O157:H7 spread into farm environment. Currently, no method is available for beef producers to eliminate shedding of E. coli O157:H7 in cattle, and the lack of information about the mechanisms of supershedding greatly impedes the development of effective methods. This study investigated the role of the bacteria found within the rectoanal junction of cattle. Our results indicated that the functions of these bacteria differed between supershedding and nonshedding cattle. Such findings provide a fundamental understanding of the supershedding phenomenon which is essential for the development of strategies to reduce E. coli O157:H7 shedding in cattle.


Cattle are the primary carrier of Escherichia coli O157:H7, a foodborne human pathogen, and those shedding > 10 CFU/gram of feces of E. coli O157:H7 are defined as supershedders (SS). This study investigated the rectoanal junction (RAJ) mucosa-associated microbiota and its relationship with host gene expression in SS and in cattle from which E. coli O157:H7 was not detected (nonshedders [NS]), aiming to elucidate the mechanisms involved in supershedding. In total, 14 phyla, 66 families, and 101 genera of RAJ mucosa-associated bacteria were identified and Firmicutes (61.5 ± 7.5%), Bacteroidetes (27.9 ± 6.4%), and Proteobacteria (5.5 ± 2.1%) were the predominant phyla. Differential abundance analysis of operational taxonomic units (OTUs) identified 2 OTUs unique to SS which were members of Bacteroides and Clostridium and 7 OTUs unique to NS which were members of Coprococcus, Prevotella, Clostridium, and Paludibacter. Differential abundance analysis of predicted microbial functions (using PICRUSt [phylogenetic investigation of communities by reconstruction of unobserved states]) revealed that 3 pathways had higher abundance (log fold change, 0.10 to 0.23) whereas 12 pathways had lower abundance (log fold change, -0.36 to -0.20) in SS. In addition, we identified significant correlations between expression of 19 differentially expressed genes and the relative abundance of predicted microbial functions, including nucleic acid polymerization and carbohydrate and amino acid metabolism. Our findings suggest that differences in RAJ microbiota at both the compositional and functional levels may be associated with E. coli O157:H7 supershedding and that certain microbial groups and microbial functions may influence RAJ physiology of SS by affecting host gene expression. 4 2 2

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