Multidrug-resistant enterobacteria colonize commercial day-old broiler chicks in Nigeria

Aim: This study was conducted to isolate generic enterobacteria from day-old broiler chicks in Nigeria, determine the antibacterial resistance profile, and assess multidrug resistance. Materials and Methods: The birds were sourced from five purposively-selected hatcheries (identified as A, B, C, D and E) in Southwest Nigeria. Non-duplicate cloacal swabs were collected from a total of 75 (15 birds per hatchery) randomly selected apparently healthy birds. Sampling was done in three batches of five chicks per batch at 2-week interval. Isolation of enterobacteria was done using MacConkey agar. The resistance of the isolates was determined using the disk diffusion method. Results: Of 15 processed samples of birds from each hatchery, all samples from hatcheries B, D, and E, 10 (66.7%) and 14 (93.3%) samples from hatcheries A and C, respectively, yielded pure cultures of Escherichiacoli. Klebsiella was also isolated from 1 (7.1%) of the 14 and 2 (13.2%) of the 15 growth-positive samples from hatcheries C and D, respectively. The range of resistance among E. coli isolates was tetracycline (86.7-100%), ampicillin (80-100%), gentamicin (60-85.7%), sulfamethoxazole-trimethoprim (46.7-92.9%), enrofloxacin (40-100%), ciprofloxacin (26.7-86.7%), streptomycin (10-80%), cefotaxime (26.7-73.3%), amoxicillin-clavulanic acid (13.3-60%), and ceftazidime (6.7-40%). Klebsiella and all E. coli isolate from chicks of hatcheries B, C, and E, 80 and 93.3% of those from chicks of hatcheries A and D, respectively, exhibited resistance to three or more classes of antibacterial agents. Conclusion: Commercial day-old broiler chicks in Nigeria are colonized by multidrug-resistant coliforms (E. coli and Klebsiella) and are potential reservoirs and disseminators of these organisms.