E. coli pathotypes identified through 16S microbiome and bacterial isolation in pigs with post-weaning diarrhea (PWD)

   

Post-weaning diarrhea (PWD) is a serious health and welfare problem for the global swine industry. PWD is a multifactorial condition occurring the first 10–14 d after weaning; it is generally associated with the proliferation of pathogenic Escherichia coli groups, specifically enterotoxigenic E. coli (ETEC); however, PWD is also associated with several viral infections. Antibiotics are commonly used as a control strategy against E. coli infections; however, the increase of antimicrobial resistance and the push toward antibiotic-free pigs highlight the importance of identifying alternative interventions. The purpose of this study was to determine the underlying bacterial cause of PWD and a potential vertical transmission from sows to pre-weaned piglets, as well as to determine whether a customized direct-fed microbial (DFM)-based product could reduce the pathogens isolated from affected pigs. A total of 120 fecal samples from a farrow to finish farm were collected for 16S microbiome analysis and bacterial isolation. These included fecal samples from (1) sows, (2) pre-weaning piglets, (3) healthy piglets after weaning, (4) and piglets with PWD. Analysis of the 16S microbiome results showed an increase in the overall level of E. coli in piglets with PWD compared with healthy piglets. Linear discriminant analysis showed that the bacterium most commonly associated with sick piglets was E. coli. These results were confirmed by plating, with E. coli isolates being recovered from all samples collected in this study. Three major groups of pathogenic E. coli were identified and confirmed by PCR, with ETEC being the most commonly isolated, followed by enteropathogenic E. coli (EPEC), and enterohemorrhagic E. coli (EHEC). A customized DFM solution was developed to target these pathotypes with a significant bacterial reduction by using 2 different inhibitory methods. Results from this study suggest the potential interaction of multiple E. coli pathotypes in the development of PWD; a customized solution could be used as an alternative intervention to reduce these pathogens and the incidence of PWD.

Key Words: Post-weaning diarrhea, pathogenic E. coli, antimicrobial effect, DFMs.

    

Presented at the 11th Symposium on Gut Health in Production of Food Animals in St. Louis, USA.