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

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 x 10(8) spores was sufficient to suppress all aspects of E. coli O78:K80 infection. Colonisation of deep organs was redu ced by a factor of over 2 log(10) whilst colonisation of the intestine, as measured by direct caecal count, was reduced over 3 log(10). Shedding of E. coli O78:K80 was measured by semi-quantitative cloacal swabbing and was re duced significantly for the: duration of the experiment, 35 days. B, subtil is persisted in the intestine although with decreasing numbers over the sam e period. Challenge with the same dose 5 days after pre-dosing with spores overcame any suppressive effect of the spores. Crown Copyright (C) 2001 Pub lished by Elsevier Science B.V. All rights reserved.