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This study was conducted to determine the overall genetic diversity, as well as prevalence and mechanisms of resistance to quinolone antibiotics of 178 Campylobacter jejuni isolated from humans, cattle, dogs, and chickens in Turkey. Multilocus sequence typing (MLST) and E-test were performed for genotyping and antimicrobial susceptibility testing, respectively. Mismatch Amplification Mutation Assay, Polymerase Chain Reaction (MAMA-PCR) was used to detect point mutations associated with quinolone resistance. Of the 178 isolates tested, 151 were included in 21 clonal complexes (CCs); the remaining 27 isolates did not belong to any existing CCs. CC21, CC353, CC206, and CC257 were the predominant clones, representing 38 % of all C. jejuni isolates tested. The isolates were assigned to 78 different sequence types (STs), three of which were novel (ST 8082, ST 8083, and ST 8084). Resistance to quinolones was found in 73 (41 %) of the isolates (42.85 %, 2.85 %, 20.58 %, and 43.75 % in human, cattle, dog, and chicken isolates, respectively). All of the resistant isolates had Thr-86-Ile mutation in the gyrA gene. The highest Sorensen coefficient index was detected for human/chicken meat and human/dog C. jejuni isolates (Ss = 0.71), suggesting a strong link between the isolates from respective sources. The Simpson diversity index of C. jejuni isolates analyzed was detected between 0.92 and 0.98. The study provides detailed information on the quinolone resistance and MLST-based genetic relatedness of C. jejuni isolates from humans, cattle, dog, and broiler meat in Turkey for the first time, enabling a better understanding of the transmission pathways of C. jejuni in this country. Our results suggest that broiler meat and dogs may be the most important sources of human campylobacteriosis in Turkey., Competing Interests: Conflict of interest The authors declare that there is no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Purpose: This study was aimed at investigating the occurrence and genetic mechanisms of resistance to ciprofloxacin, tetracycline and erythromycin in clinical isolates of Campylobacter jejuni recovered from human cases of acute gastroenteritis in Turkey., Methodology: MIC values of each antibiotic were determined with the epsilometer test (E-test). Resistance genes/mutations were first screened by PCR and analysed by subsequent DNA sequencing., Results: From a total of 152 C. jejuni isolates tested, 113 (74.3%), 38 (25%) and 9 (5.9%) were found to be resistant to ciprofloxacin, tetracycline and erythromycin, respectively. Sequence analysis of ciprofloxacin-resistant isolates showed that all resistant strains (n=113) carried Thr-86-Ile substition in the gyrA gene, which is the most frequently observed mutation in fluoroquinolone-resistant Campylobacter. All of the tetracycline-resistant isolates (n=38) carried the tetO gene. All of the erythromycin-resistant isolates (n=9) harboured the point mutation A2075G in the 23S rRNA gene, which is the most common mutation conferring macrolide resistance in C. jejuni., Conclusion: The phenotypic susceptibility testing results were found to agree well with those obtained by genetic detection methods for the C. jejuni isolates tested. The findings of this study showed a very high level of resistance to ciprofloxacin and to a lesser extent to tetracycline while resistance to erythromycin remained at a low level. Thus, erythromycin may be considered as the first choice for treatment of Campylobacter infections in this geographical region when indicated.

In this study, the investigation of clonal relations between human and poultry Campylobacter jejuni isolates and the determination of susceptibilities of isolates to various antibiotics were aimed. A total of 200 C. jejuni isolates concurrently obtained from 100 chicken carcasses and 100 humans were genotyped by the Pulsed-Field Gel Electrophoresis (PFGE) and automated Repetitive Extragenic Palindromic PCR (Rep-PCR, DiversiLab system) methods and were tested for their susceptibility to six antibiotics with disk diffusion method. The minimum inhibitory concentration (MIC) values of ciprofloxacin (CI), enrofloxacin (EF) and erythromycin (EM) were evaluated by E-test. By using PFGE 174 of (87.0%) the isolates were able to be typed. The clonally related strains were placed in 35 different clusters and 115 different genotypes were obtained. All of the two hundred isolates could be typed by using Rep-PCR and were divided into 133 different genotypes. One hundred and fourteen clonally related isolates (57.0%) were included in 47 clusters. In disk diffusion test, while the susceptibility rates of AMC and S to human and chicken derived C. jejuni isolates were 84.0%-96.0% and 96.0%-98.0%, respectively, all isolates were susceptible to gentamicin. The resistance rates of human isolates to AMP, NA and TE were detected as 44.0%, 84.0% and 38.0% of the resistances of chicken isolates to these antibiotics were 34.0%, 95.0% and 56.0%, respectively. The MIC values of human and chicken isolates to CI, EF and EM were detected as 81.0-93.0%, 85.0-88.0% and 6.0-7.0%, respectively. The clonal proximity rates were detected between human and poultry origin C. jejuni isolates. The discriminatory power of PFGE and Rep-PCR was similar, with Simpson's diversity indexes of 0.993 and 0.995, respectively. Concordance of the two methods as determined by Adjusted Rand coefficient was 0.198 which showed the low congruence between Rep-PCR and PFGE. High rates of quinolone resistance were detected in C. jejuni isolates. This study demonstrated that chicken meat played an important role for infections caused by C. jejuni in Turkey and erythromycin, amoxicillin clavulanic acid and gentamicin are recommended for the treatment of Campylobacteriosis in humans., (Copyright © 2014 Elsevier B.V. All rights reserved.)