Poultry Environment as a Reservoir of Antimicrobial Resistant Bacteria – A Nigerian Story

Aims: This study set out to help define the role of the poultry environment as a reservoir of drug resistant bacteria in Nigeria.

Introduction: The poultry environment has been acclaimed as a potential source of antimicrobial resistant bacteria but information is lacking in Nigeria. Despite worldwide control strategies, a predominance of small-scale poultry farming poses a challenge to proper veterinary monitoring in Nigeria.

Methodology: Three commercial laying farms were sampled and total heterotrophic counts determined. Bacterial identification, susceptibility profile and multiple antibiotic resistance (MAR) index and diversity index were determined using standard methodologies.

Results: Higher bacterial counts were observed in litter than feed samples (6.7 × 107 to 1.6 × 109 CFU/g versus 2.2 × 105 to 3.5 × 106 CFU/g) and majority of isolates (73.2%) belonged to only 5 bacterial species (Escherichia coli, Staphylococcus aureus, Enterobacter aerogenes, Klebsiella pneumoniae and Bacillus sp). With respect to antibiotic resistance in general, both litter and faecal matter isolates exhibited similar average rates of 62.2% and 63.1% respectively. Feed samples however had a lower average rate of 46.8%. A similar trend was observed when considering rates of multidrug resistance (MDR). Litter and faecal isolates had MDR rates of 88% and 91% respectively, while feed isolate had a MDR rate of 73%. A focus on the antibiograms of Bacillus cereus, Staphylococcus aureus and Escherichia coli specifically revealed a wide diversity among these isolates with 31 antibiotic resistance patterns observed from 55 isolates and a diversity index of 0.88, 0.9 and 0.98 respectively.

Conclusion: These findings indicate that the Nigerian poultry environment may serve not only as a reservoir of antibiotic resistant organisms, but also as an environment for the development of this resistance. A continuous monitoring of the situation is of essence to form the basis of future intervention strategies.