Efficacy of two probiotics in the control of Escherichia coli O157:H7 in experimentally infected lambs

This study was designed to determine the efficacy of probiotics mixture in the control of Shiga-toxin Escherichia coli (STEC) O157:H7 in experimentally infected lambs. Fifteen Yankassa breed of lambs aged between 3-4 weeks old were used. The lambs were divided into three groups of five lambs each (n=5).  Group A: Neither probiotics nor STEC O157:H7 were administered (control), Group B: lambs were administered viable STEC O157:H7 cells at 6 x 108CFU/ml  together with daily administration of probiotics  mixture at 4.5 x108 CFU/ml, Group C: lambs were administered only viable STEC O157:H7 cells at 6x108 CFU/ml without probiotics. Faecal samples from all the experimental lambs were screened for the presence of STEC O157:H7 before the commencement of this study using Tryptone soy broth (TSB) as an enrichment media and Cefixine-tellurite sorbitol MacConkey agar (CT-SMAC) as a selective media. Following oral inoculation of the lambs with STEC cells, faecal samples were collected once weekly for six weeks, for STEC O157:H7 isolation and enumeration. STEC O157:H7 was confirmed by its reaction with O157 and H7 anti-sera (Wellcomexr). STEC O157:H7 was not shed by lambs in group A (control). However, Group B lambs administered a mixture of probiotics shed significantly lower (P<0.05) counts of STEC cells in the six weeks post-infection than Group C lambs that received only STEC cells without probiotics. In conclusion, the use of probiotics mixture significantly (P<0.05) reduced the faecal shedding of STEC O157:H7. It was therefore recommended that probiotics should be administered to lambs to help control these pathogens. Key words: Shiga-toxin producing Escherichia coli O157:H7, probiotics mixture, cefixime-tellurite Sorbitol MacConkey Agar, tryptone soy broth, anti-sera.