Abstract

The increasing incidence of enterobacteriosis in poultry birds in Nigeria lately necessitated the study which aimed at enumerating the Enterobacteriaceae in 58 commercially available poultry feeds, studying their antibiotic susceptibility pattern, confirming plasmid as the determinants of resistance and tracing the relationship between multidrug resistant (MDR) isolates in the feed and those in morbid birds. Fifty-three enterobacteria belonging to 5 genera: Escherichia, Salmonella, Klebsiella, Enterobacter, Yersinia; were obtained from the feed samples. Escherichia coli was the most distributed enterobacteria in the feed types (80%). There was a significant (P<0.05) trend in overall percentage distribution of contaminating enterobacteria across feed types in the order: chick mash > broiler starter > broiler finisher > growers mash > layers mash. Augmentin, nitrofurantoin and amoxicillin showed the least overall potency (<30%) against all isolates while sensitivity to fluoroquinolones was above 70%. Multidrug (MD) resistance was limited to 32.1% of the isolates. The plasmid DNA profiles showed that 71.4% of the analyzed MDR strains possessed extrachromosomal determinants with relative sizes of 6.4 to 23.0 kb. The similarity studies showed that there was a direct relationship between MDR E. coli strains from the feed samples and those from morbid birds (S_i = 78.9%).

Key words: Enterobacteriaceae, poultry feed, antibiogram, multidrug resistance, plasmid.