Extended-spectrum beta-lactamase-producing Escherichia coli in chickens from small-scale (backyard) poultry farms in Maiduguri, Nigeria

Aim: This study investigated the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in chickens from small-scale (backyard) commercial poultry farms in Maiduguri. Materials and Methods: A total of 96 cloacal swab samples were collected. This comprised of 24 samples each from broiler chicks, pullets, layers, and broilers (adults). The samples were examined for the presence of E. coli using conventional microbiological culture and biochemical tests. The pure E. coli isolates were screened for ESBL production by culturing onto BrillianceTM ESBL agar. Isolates that showed positive reactions with production of bluish or pinkish colonies were tested for susceptibilities against some selected β-lactam antibiotics which include cefotaxime (30 μg), ceftriaxone (30 μg), cefpodoxime (10 μg), aztreonam (30 μg), and ceftazidime (30 μg). Isolates that exhibited resistance to any two or three of the antibiotics were selected and confirmed by combination disk diffusion method with ceftazidime (30 μg) and cefotaxime (30 μg) alone and in combination with clavulanic acid (30 μg/10 μg). Results: The total occurrence of E. coli was 67.6% (65/96) with the highest occurrence of 83.3% (20/24) from broiler chicks and least detection of 54.2% (13/24) from layers. Of this, 32.0% were ESBL-producing E. coli with the highest detection rate from layers (38.5%) and least occurrence from pullets (26.7%). Conclusion: This study revealed the presence of ESBL-producing E. coli in chickens from small-scale commercial poultry farms in Maiduguri, thus indicating that chickens may serve as important reservoirs for the transmission of antimicrobial resistant pathogens to humans through the food chain.