Investigation of the prevalence and important virulence characteristics of closti̇di̇um perfringens isolates in broilers by molecular typing and determination of their antibiotic sensitivity

After the prohibition of antibiotic-growth-factors, the emergence of Clostridium perfringens-related diseases and the growing prevalence of multi-drug-resistant pathogens highlight the necessity of researches in this area. Hence, this study aimed to identify C. perfringens isolates, assess their virulence potential, prevalence and determine their antimicrobial resistance status. In this study, 60(26.9%) C. perfringens strains were identified by PCR, determined as type A (n=60) and confirmed by the cpa gene, and 13, 12, 3 strains carried the tpeL, cpe, cpb2 genes, respectively. Internationally accepted criteria haven't yet been totally established in the interpretation of the antibiogram results for C. perfringens. Therefore, the evaluation of disk diffusion test was done based on inhibition-zone of penicillin-G as a reference, in comparison to MIC results performed according to EUCAST, CLSI, and the breakpoints and the criteria presented by the researchers, for those not included in both guidelines. In the disk diffusion test, 2 strains resistant to penicillin were found and weren't included in the evaluation. All of the strains were resistant to aminoglycosides, 77.6% to lincomycin, 55.2% to erythromycin, 53.4% to norfloxacin, 48.3% to tetracycline. MDR was found in 74.1%(43/58) of the strains. The agar dilution MIC test results of 22 strains, including penicillin-resistant strains, were evaluated for 7 most commonly used antibiotics. According to MIC results, all the strains were resistant respectively to gentamicin, 68.2% to lincomycin, 45.5% to erythromycin, 40.9% to tetracycline, 36.4% to enrofloxacin, 9.1% to penicillin, 4.5% to ampicillin. MDR was determined in 55%(11/20) of these strains according to the agar dilution method and 75% (15/20) according to the disc diffusion method. In this study, only type A strains were isolated and tpeL, cpe, cpb2 virulence genes were determined. This is consistent with the data on healthy-chicken microflora. In addition, the results of MDR suggest the necessity of monitoring C. perfringens antibiotic-resistance.