Phylogrouping and genotyping of mcr-1 postives avian pathogenic Escherichia coli isolates in Algerian poultry farms.

Colibacillosis is a highly prevalent bacterial disease in poultry, resulting in the widespread use of antibiotics for both curative and preventive purposes. Consequently, avian pathogenic Escherichia coli (APEC) continues to act as a reservoir for antibiotic resistance genes, including the mcr-1 gene, which codes for resistance to colistin, a crucial antibiotic in human medicine. The aim of this study was to evaluate the antibiotic resistance pattern of APEC and to investigate the genotyping, phylogrouping, and virulence of mcr-1-positive isolates. A total of 113 APEC were isolated, of which 92% were multidrug resistant (MDR). The mcr-1 gene was detected in 41 isolates originating from turkeys and broilers. Two isolates carried blaTEM, one of which also harboured blaCTX-M encoding beta-lactamases. The Clermont phylogrouping revealed that 76% of the isolates belonged to phylogroup B1. Concerning the detection of the virulence-associated genes, 88% of isolates carried at least 3 genes. The ERIC-PCR classified our isolates into 6 different clusters. Our study highlights the emergence of colistin resistance and MDR, which pose a real threat to poultry production and public health. Control of antibiotic use in the poultry sector is urgent and mandatory.