Colistin-Resistant Enterobacterales Isolated from Chicken Meat in Western Algeria

In Algeria, colistin is used as a metaphylactic treatment in the poultry industry for the treatment of Gram-negative gastrointestinal infections and also as a feed additive to promote animal growth. The aim of this study was to investigate the importance and genetic characteristics of colistin-resistant Enterobacterales from chicken meat in Western Algeria. A total of 181 samples of chicken meat were collected from three poultry farms across three provinces in Western Algeria. The presence of colistin-resistant Enterobacterales isolates was screened on selective media. Resistance and virulence profiles were characterised by PCR and sequencing. The clonal relatedness of the different mcr positive isolates was studied using repetitive sequence-based PCR (Rep-PCR) and multilocus sequence typing. Transferability and characteristics of plasmids harboring mcr-1 positive gene were performed using conjugation, PCR-based replicon typing, and whole-genome sequencing. A total of 22 isolates with acquired colistin resistance were identified giving an overall prevalence of 12.2% (22/181): 17 Escherichia coli (predominantly ST224 [n = 4, 23.5%]) and 5 Klebsiella pneumoniae (ST17 [n = 2, 40%], ST646 [n = 2, 40%], and ST944 [n = 1, 20%]). mcr-1 gene was exclusively found in 11 E. coli (prevalence of 6.1% [11/181]) and was associated with IncFV (n = 7) and IncFIIK (n = 4) plasmids. All the isolates had a commensal origin (n = 11). One isolate harbored virulence profile, a high colistin resistance (minimum inhibitory concentration = 96 mg/L), with some new mutations in the chromosomic colistin-resistant genes and different pathogenicity islands typically identified in uropathogenic E. coli. This study reports the diffusion of mcr-1 producing Enterobacterales from chicken meat in Western Algeria. This represents a worrisome situation needing continuous monitoring.