Colistin Resistance in Multidrug-Resistant <i>Escherichia coli</i> Isolated from Retail Broiler Meat in Bangladesh

Abstract

The emergence of colistin resistance in <i>Escherichia coli</i> is a global public health concern. Contaminated food can accelerate the spread of colistin-resistant <i>E. coli</i> to humans. This study aimed to detect and characterize colistin-resistant <i>E. coli</i> from broiler meat in Bangladesh. We analyzed 136 pooled broiler meat samples from 240 carcasses collected from 40 live bird markets in urban and rural areas and 8 metropolitan supermarkets. The mean count of <i>E. coli</i> in broiler meat samples collected from rural retail shops, metropolitan supermarkets, and urban retail shops was 5.3 ± 1.1, 4.1 ± 1.4, and 3.9 ± 0.8 log₁₀ colony-forming unit per gram, respectively. Colistin-resistant <i>E. coli</i> (minimum inhibitory concentration >2 mg/L) was found in 78% (95% confidence interval 70.2-84.1%) of the samples. All colistin-resistant isolates harbored the <i>mcr</i>-<i>1</i> gene, while the rest of the <i>mcr</i> genes (<i>mcr</i>-<i>2</i> to <i>mcr</i>-<i>9</i>) were not detected. Most colistin-resistant <i>E. coli</i> isolates (98%) showed coresistance to tetracycline, sulfamethoxazole/trimethoprim followed by ciprofloxacin (95%). Alarmingly, all of the colistin-resistant isolates were found to be multidrug resistant. Phylogenetic analysis showed close similarities of the <i>mcr</i>-<i>1</i> gene sequences of this study with many strains of Enterobacterales isolated from humans, animals, and the environment. This study detected colistin-resistant <i>E. coli</i> contamination in broiler meat, which can pose a serious public health threat.