Bacillus subtilis spores competitively exclude Escherichia coli O78:K80 in poultry

Abstract

Newly hatched specific pathogen-free chicks were dosed with a suspension of Bacillus subtilis spores prior to challenge with Escherichia coli O78:K80, a known virulent strain associated with avian colibacillosis, 24 h later. A single oral inoculum of 2.5×108 spores was sufficient to suppress all aspects of E. coli O78:K80 infection. Colonisation of deep organs was reduced by a factor of over 2 log10 whilst colonisation of the intestine, as measured by direct caecal count, was reduced over 3 log10. Shedding of E. coli O78:K80 was measured by semi-quantitative cloacal swabbing and was reduced significantly for the duration of the experiment, 35 days. B. subtilis persisted in the intestine although with decreasing numbers over the same period. Challenge with the same dose 5 days after pre-dosing with spores overcame any suppressive effect of the spores. Crown Copyright © 2001 Published by Elsevier Science B.V.