Feeding the Probiotic Enterococcus faecium Strain NCIMB 10415 to Piglets Specifically Reduces the Number of Escherichia coli Pathotypes That Adhere to the Gut Mucosa

Feed supplementation with the probioticEnterococcus faecium for piglets has been found to reduce pathogenic gut microorganisms. SinceEscherichia coli is among the most important pathogens in pig production, we performed comprehensive analyses to gain further insight into the influence ofE. faecium NCIMB 10415 on porcine intestinalE. coli . A total of 1,436E. coli strains were isolated from three intestinal habitats (mucosa, digesta, and feces) of probiotic-supplemented and nonsupplemented (control) piglets.E. coli bacteria were characterized via pulsed-field gel electrophoresis (PFGE) for clonal analysis. The high diversity ofE. coli was reflected by 168 clones. Multilocus sequence typing (MLST) was used to determine the phylogenetic backgrounds, revealing 79 sequence types (STs). Pathotypes ofE. coli were further defined using multiplex PCR for virulence-associated genes. While these analyses discerned only a few significant differences in theE. coli population between the feeding groups, analyses distinguishing clones that were uniquely isolated in either the probiotic group only, the control group only, or both groups (shared group) revealed clear effects at the habitat level. Interestingly, extraintestinal pathogenicE. coli (ExPEC)-typical clones adhering to the mucosa were significantly reduced in the probiotic group. Our data show a minor influence ofE. faecium on the overall population ofE. coli in healthy piglets. In contrast, this probiotic has a profound effect on mucosa-adherentE. coli . This finding further substantiates a specific effect ofE. faecium strain NCIMB 10415 in piglets against pathogenicE. coli in the intestine. In addition, these data question the relevance of data based on sampling fecalE. coli only.