Abstract

To assess the prevalence of antibiotic resistance in Nigeria, single Escherichia coliisolates were collected from a geographically diverse panel of fecal samples collected from human clinical and non-clinical donors (n=77), livestock (cattle, swine, and goats) and chickens (n=71 total). There was no difference in the proportion of isolates resistant to ≥1 antibiotics from human clinical and non-clinical samples, but overall, this was significantly higher for human (85.7%) compared to animal (53.5%) isolates (P<0.0001). The average number of resistance phenotypes per isolate was significantly higher for human (5.0), goat (4.0), and poultry (3.4) compared with cattle (2.4) and swine (2.0) (P<0.05). There were 25 different resistance phenotypes with more diversity from animal compared with human isolates. A survey of management practices at 30 poultry farms in the vicinity of Ibadan found that all respondents self-milled feed and most (87.7%) routinely added antibiotics to feed. Tetracyclines were the dominant antibiotics of choice followed by tylosin and gentamicin and some use of chloramphenicol, ciprofloxacin, and enrofloxacin. If this pattern of antibiotic resistance and use is repeated across the different sectors of food-animal production and in multiple developing countries, then trade and travel are likely to disseminate resistance traits to other countries potentially negating local policies that are designed to limit selection for antibiotic resistant bacteria.

Key words: Antibiotic resistance, Escherichia coli, growth promotion, poultry, chloramphenicol.