Phenotypic and genotypic examination of antimicrobial resistance in thermophilic Campylobacter species isolated from poultry in Turkey

Introduction: The study aimed to isolate thermophilic Campylobacter from chickens raised three rearing methods, determine its antimicrobial susceptibilities, and examine resistance-related genes by PCR. Material and Methods: Cloacal swabs or intestinal contents were taken in Istanbul, Sakarya, and Izmir provinces. Chickens were from small village-based family-run businesses (n = 70), organically raised (n = 71), and conventionally raised broilers (n = 79). The samples were cultured on modified charcoal cefoperazone desoxycholate (mCCD) agar. Suspect isolates were identified with multiplex PCR (mPCR). As per EUCAST standards, MIC values were derived by broth micro dilution for tetracycline, ciprofloxacin, nalidixic acid, kanamycin, gentamicin, and erythromycin in isolates of C. jejuni (n = 98) and C. coli (n = 83). Results: In C. jejuni, 78.6% tetracycline, 87.8% ciprofloxacin, and 81.6% nalidixic acid resistance was detected, but none was to kanamycin, gentamicin, or erythromycin. In C. coli, 98.8% ciprofloxacin and 63.9% nalidixic acid resistance was detected, whereas resistance to non-quinolones was not observed. C257T (Thr-86-Ile) mutation in the gyrA gene of all phenotypically quinolone-resistant isolates was detected through a mismatch amplification mutation assay PCR (MAMA-PCR). It emerged that all isolates bore the tet (O) resistance gene. Conclusion: Common tetracycline, nalidixic acid, and ciprofloxacin resistance exists in Campylobacter isolated from chickens raised three rearing methods.