Genetic diversity and antibiogram of ESBL-producing Escherichia coli isolated from apparently healthy birds sold at two selected live bird markets in Nigeria.

Abstract

Background: Live bird markets (LBMs) play a crucial role in the poultry value chain. However, there is a significant threat of antibiotic resistance development via this chain. This study aimed to characterise ESBL-producing Escherichia coli (E. coli) from cloacal samples of apparently healthy ducks and pigeons, determine their antibiotic resistance profile and carriage of ESBL genes.

Methods and results: Sasa and Molete LBMs were selected for this study. Three hundred and forty cloacal swabs (170 each from ducks and pigeons) were sampled and isolation of E. coli was done using the streak plate method. Resistance to a panel of 10 antibiotics was determined using the disc diffusion method and phenotypic ESBL production was carried out using the double disc synergy test (DDST). Detection of ESBL genes in the isolates was done using PCR amplification method. Out of 340 samples, 22.9% (n = 78) tested positive for E. coli. Among these, 38.5% (n = 30) were positive for ESBL production. The thirty ESBL-producing isolates showed varying level of resistance to the tested antibiotics, with the highest level of resistance observed to imipenem in both ducks and pigeons. Twenty of the ESBL producers showed multidrug-resistant phenotypes. bla_CTX-M which was detected in 19 isolates (63.3%) was the most predominant ESBL gene among the isolates, while 15/30 (50.0%) carried bla_SHV and 6/30 (20.0%) carried bla_TEM. Thirteen (43.3%) and two (6.6%) isolates co-harboured two and all the three target ESBL genes, respectively.

Conclusions: This study has shown that LBMs in Ibadan are a repository of multidrug-resistant and ESBL-producing E. coli, hence urgent measures need to be taken to monitor and control the use of antibiotics in LBMs to mitigate this risk.