Comparison of Diversity in MIC50 and MIC90 of antibiotics in Campylobacter isolates from Chicken Meat and Stool Samples of Symptomatic Patients in Tehran, Iran.

Background and Objectives: Campylobacter is one of the major causes of human infections worldwide. Transmission of resistant strains from the poultry farms to the community is a therapeutic challenge. The aim of this study was to determine diversity in resistance patterns and minimal inhibitory concentrations between the human and chicken meat Campylobacter isolates in Tehran, Iran. Materials and Methods: A total of 400 stool samples from people with community acquired gastroenteritis, and 100 chicken meat samples from shopping centers were collected from 22 districts of Tehran. The presence of C. jejuni, C. coli, C. lari, and C. upsaliensis among the isolates were characterized by PCR methods. Identification of antibiotic resistance to7 antibiotics and multidrug resistance patterns were detected by E-test and disc diffusion methods, as described by EUCAST and CLSI guidelines published in 2018. MIC50 and MIC90 were measured based on the determined MIC values. Results: Out of the Campylobacter isolates from the chicken meat and the stool samples (35 and 28 isolates, respectively), highest resistance rates were detected to tetracycline (62.9 and 53.6%), ciprofloxacin (51.4 and 28.6%), and nalidixic acid (42.9 and 28.6%), while lowest rates of resistance were against ampicillin (17.1 and 50%) and clindamycin (17.1 and 39.3%), respectively. Although resistance to ampicillin was higher among the human samples (50% vs 17.1%), these isolates showed lower resistance rates to nalidixic acid and ciprofloxacin (28.6 and 28.6% vs 42.9 and 51.4%, respectively). The MICs of each antimicrobial for each isolate examined, together with the minimum concentrations of each antimicrobial required to inhibit 50% (MIC50) and 90% (MIC90) of the isolates examined, were also determined. MIC50 and MIC90 values for the chicken meat and human feces isolates were as follows: clindamicin (4 and 32 vs 6 and 16 μg/ml), gentamicin (16 and 32 vs 4 and 32 μg/ml), ampicillin (16 and 64 vs 16 and 64 μg/ml), nalidixic acid (32 and 128 vs 12 and 64 μg/ml), tetracycline (15 and 27 vs 19 and 27 μg/ml), erythromycin (15 and 25 vs 16 and 27 μg/ml), ciprofloxacin (19 and 27 vs 22 and 27 μg/ml), respectively. Conclusion: Similarity of the MIC values and frequency of resistance patterns to antibiotics between the Campylobacter isolates from chicken meat and human feces samples were demonstrated in this study. Further studies are needed to show this association at molecular levels.