Molecular Detection of Extended Spectrum Beta-lactamase Resistance in Escherichia coli from Poultry Droppings in Keffi, Nigeria

Objectives: The present study reports extended-spectrum beta-lactamase (ESBL) production in E. coli isolates from poultry droppings from selected poultry farms in Keffi, Nigeria.

Methods: Seventy-five (75) samples of poultry droppings were collected, and E. coli was isolated using standard microbiological methods. Antibiotic susceptibility testing and minimum inhibitory concentrations were evaluated as described by the Clinical and Laboratory Standards Institute (CLSI). Phenotypic confirmation of ESBL production by the isolates was carried out using double disc synergy test. Molecular detection of ESBL genes was carried out using Polymerase Chain Reaction (PCR) method.

Results: All (100%) samples had E. coli. Antimicrobial resistance in the isolates were as follows: imipenem (12.0%), gentamicin (20.0%), cefoxitin (37.3%), cefotaxime (41.3%), ceftazidime (44.0%), ciprofloxacin (48.0%), amoxicillin/clavulanic acid (58.7%), streptomycin (92.0%), sulphamethoxazole/trimethoprim (92.0%) and ampicillin (98.7%). Joint resistance to ampicillin, sulphamethoxazole/trimethoprim-streptomycin was the commonest resistance phenotype at 10.6%. Multiple antibiotic resistance (MAR) was observed in 97.3% (73/75) of the isolates; and the most common MAR indices were 0.7 (21.9%), 0.5 (17.8%), 0.4 (16.4%), 0.8 (11.1%) and 0.3 (10.9%). Twenty three (46.9%) of the 49 cefotaxime/ceftazidime isolates were confirmed ESBL producers. Twenty-two of the 23 ESBL positive isolates (95.7%) carried the bla genes as follows: 95.5% (21/22) for blaSHV; 68.2% (15/22) for blaTEM; and 50.0% (11/22) for blaCTX-M. Eleven (50%) of the 22 isolates carried two bla genes (blaSHV and blaCTX-M, blaTEM and blaCTX-M and blaTEM and blaSHV).

Conclusion: The E. coli isolates were less resistant to imipenem, gentamicin and cefoxitin; most isolates were MAR, with resistance to 7 antibiotics being the most predominant. In addition, the blaSHV gene was the most common ESBL gene detected in confirmed ESBL-producing E. coli isolates.