First report of detection of mcr -1 and virulence genes in avian pathogenic Escherichia coli in the center of Algeria

Antimicrobial resistance in avian pathogenic (APEC) represents a major concern in the avian industry worldwide and limited studies have investigated Colistin resistance among APEC in Algeria. Investigate antibiotic resistance, in particular, Colistin, and mediated-Colistin resistance ( ) genes, as well as the virulence genes in APEC. One hundred were isolated from poultry suspected of colibacillosis. Antimicrobial susceptibility testing was done on 14 antibiotics by the disk diffusion method. Colistin minimum inhibitory concentration (MIC) was assessed by the broth microdilution method. Using multiplex PCR, genes ( -1 to 5) and 7 virulence-related genes were investigated in Colistin-resistant isolates. Results showed high resistance to Tetracycline (99%), Nalidixic acid (92%), Doxycycline (90%), Ampicillin (89%), Ofloxacin (74%), Sulfamethoxazole-Trimethoprim (72%), and Amoxicillin-Clavulanic acid (57%); in addition, 92% of isolates were multidrug resistant. The rate of resistance to Colistin was 27% (27/100) of which 96.3% (26/27) of isolates carried the -1 gene. Twenty-five of the Colistin-resistant isolates (92.59%) had at least three virulence genes. The most frequently isolated virulence genes were: (96.3%) followed by , , and (77.7%, each), and were found in 59.25% and 55.5% of isolates, respectively. The most prevalent combination of virulence factors was . This is the first report which highlighted Colistin resistance with the detection of 1 in APEC isolates in the area of study. Colistin resistance and carriage of -1 in virulent and multidrug-resistant isolates of are alarming and a surveillance program to limit the spread of these pathogens is mandatory.