Investigation of the mobile colistin resistance gene-1 in avian pathogenic Escherichia coli

Objective: This study aimed to determine the presence of mobilized colistin resistance gene 1 (mcr-1), which provides plasmid-mediated colistin resistance in poultry pathogenic Escherichia coli (APEC) isolates, and to examine the antibiotic resistance profiles of colistin resistant isolates. Material and Methods: In this research, 200 broiler liver samples suspected of colibacillosis were utilized as the material. Following the isolation of E. coli through classical conventional methods, identification and antibiotic susceptibility tests were conducted using an automated microbiology system (BD Phoenix 100TM, USA). The presence of the mcr-1 gene in isolates phenotypically determined as colistin-resistant was investigated using polymerase chain reaction (PCR). Results: Out of 156 (78%) E. coli isolates obtained from 200 broiler liver samples, 10 (6.4%) were phenotypically determined to be colistin-resistant. It was found that 80% of colistin resistant E. coli isolates were resistant to levofloxacin, 70% to cefazolin and cefuroxime, 60% to ceftazidime, 50% to gentamicin and ceftriaxone, 40% to cefepime, 30% to ceftolozane tazobactam, and 20% to piperacillin-tazobactam. All isolates were sensitive to amikacin, ertapenem, imipenem, meropenem, and resistant to ampicillin, amoxicillin-clavulanate, ampicillin-sulbactam, trimethoprim-sulfamethoxazole, and tigecycline, exhibiting multidrug resistance (MDR). All isolates that were found to be phenotypically resistant to colistin were also found to carry the mcr-1 gene genotypically. Conclusion: These findings indicate that the mobilize colistin resistance in APEC isolates contributes to the rapid spread of plasmid-mediated resistance genes and the escalation of broad-spectrum antibiotic resistance. The detection of resistance to antibiotics used in human medicine may be poses a potential threat to public health. Future studies should be conducted with samples from different regions and include a diverse sample group to better understand this risk.