Escherichia coli Probiotic Strain ED1a in Pigs Has a Limited Impact on the Gut Carriage of Extended-Spectrum-β-Lactamase-Producing E. coli

Four trials were conducted to evaluate the impact ofEscherichia coli probiotic strain ED1a administration to pigs on the gut carriage or survival in manure of extended-spectrum-β-lactamase-producingE. coli . Groups of pigs were orally inoculated with strainE. coli M63 carrying thebla CTX-M-1 gene (n = 84) or used as a control (n = 26). In the first two trials, 24 of 40E. coli M63-inoculated pigs were givenE. coli ED1a orally for 6 days starting 8 days after oral inoculation. In the third trial, 10E. coli M63-inoculated pigs were given eitherE. coli ED1a or probioticE. coli Nissle 1917 for 5 days. In the fourth trial,E. coli ED1a was given to a sow and its 12 piglets, and these 12 piglets plus 12 piglets that had not receivedE. coli ED1a were then inoculated withE. coli M63. Fecal shedding of cefotaxime-resistantEnterobacteriaceae (CTX-RE) was studied by culture, andbla CTX-M-1 genes were quantified by PCR. The persistence of CTX-RE in manure samples from inoculated pigs or manure samples inoculatedin vitro withE. coli M63 with or without probiotics was studied. The results showed thatE. coli M63 and ED1a were good gut colonizers. The reduction in the level of fecal excretion of CTX-RE inE. coli ED1a-treated pigs compared to that in nontreated pigs was usually less than 1 log10 CFU and was mainly observed during the probiotic administration period. The results obtained withE. coli Nissle 1917 did not differ significantly from those obtained withE. coli ED1a. CTX-RE survival did not differ significantly in manure samples with or without probiotic treatment. In conclusion, under our experimental conditions,E. coli ED1a andE. coli Nissle 1917 could not durably prevent CTX-RE colonization of the pig gut.