and Activity of L14 Strain Against DC3 Strain.

Introduction: Domestic poultry is a natural reservoir of , the host-pathogen interaction being predominantly asymptomatic. This study investigated whether chickens remain asymptomatic partly because of lactic acid bacteria (LAB).

Material And Methods: spp. and LAB were isolated from the gut of poultry chickens using enrichment and screening assays and were identified rDNA sequencing. The DC3 isolate was grown in different cell-free supernatants (CFS) generated from a priority LAB isolate. An challenge involving the and LAB isolates using a chicken model was performed to confirm the findings.

Results: Twelve presumptive LAB isolates had anti- activity based on cross-streak and agar plug assays, with L14 isolate exhibiting the highest activity. Inhibition by L14 CFS of the growth of occurred in a dose-dependent manner. DC3 inhibition was most evident in CFS harvested at 72 h and produced by co-culture with the pathogen. Neutralisation of the CFS abrogated the observed inhibition. Co-infection with DC3 and L14 , however, failed to inhibit colonisation in chickens.

Conclusion: The results suggest that the anti- effect of L14 in chickens may be due to mechanisms other than direct inhibition of growth.