Antimicrobial Resistance Pattern of Clostridium Perfringens Isolated From Broilers

The global broiler business is heavily impacted financially by Clostridium perfringens, the main cause of necrotic enteritis (NE). In this work, C. perfringens obtained from NE cases in broiler chickens was examined for prevalence, antimicrobial resistance profiles, and antibiotic resistance genes. Out of 434 collected samples, C. perfringens was detected in 166 samples (38.3%). Among these, 137 of 203 intestinal samples (67.5%) and 20 of 141 liver samples (14.2%) from diseased birds (157 of 344; 45.6%) tested positive, along with 9 of 90 (10%) intestinal samples from apparently healthy birds. Identification was confirmed using both conventional and molecular methods. According to antimicrobial susceptibility tests, streptomycin had the highest resistance rates, followed by erythromycin, ampicillin, penicillin G, cefotaxime, tetracycline, ciprofloxacin, amikacin, rifampicin, and amoxicillin/clavulanic acid. Conversely, the lowest resistance was observed against imipenem. Notably, 100% of the isolates of C. perfringens exhibited multidrug resistance (MDR). Molecular screening for resistance genes revealed a high prevalence of the macrolide resistance gene ermB (141/166; 84.9%), β-lactamase resistance gene blaCTX (114/166; 68.7%), tetracycline resistance gene tetM (77/166; 46.4%), and fluoroquinolone resistance genes qnrA (119/166; 71.7%), qnrB (85/166; 51.2%), and qnrS (20/166; 12.0%). These results demonstrated that multidrug-resistant C. perfringens is highly prevalent in broilers and underscore the need for routine monitoring of antimicrobial susceptibility to inform effective control strategies and mitigate the spread of resistance.