Day-old chicks are important source of introduction of multidrug-resistant enterobacteria in broiler production chain. This study was conducted to isolate generic enterobacteria from day-old broiler chicks in Nigeria, and to determine the antibacterial resistance profile. The birds were sourced from 5 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 3 batches of 5 chicks per batch at 2-week interval. Isolation of enterobacteria was done using MacConkey agar. Resistance of the isolates was determined using disc diffusion method. Out 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 E. coli. 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 overall median values of resistance for the E. coli isolates was AMP and ENR (100%), SXT and TET (92.9%), GEN and CIP (85.7%), CTX (57.1%), CTZ and STR (28.6%), and AMC (21.4%). All the E. coli isolates from chicks of hatcheries B, C, and E, 80% and 93.3% of those from chicks of hatcheries A and D, and the Klebsiella isolates, exhibited resistance to at least a drug in 3 or more classes of antibacterial agents tested. This study has shown that 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.

Keywords: multidrug-resistant, coliforms, Enterobacteriaceae, day-old-chicks, avian