Prevalence, Risk Factors, Antimicrobial Resistance and Molecular Characterization of in Northeast Tunisia Broiler Flocks

This study was conducted in northeastern Tunisia to estimate both the prevalence and the risk factors of in broiler flocks as well as to characterize the isolated multidrug-resistant (MDR) strains. In the present study, a total number of 124 farms were sampled; isolates were identified by the alternative technique . The susceptibility of isolates was assessed against 21 antimicrobials using the disk diffusion method on Mueller-Hinton agar using antimicrobial discs. Some antimicrobial resistance genes were identified using PCR. The prevalence rate of infection, in the sampled farms, was estimated at 19.9% (64/322). Moreover, a total number of 13 different serotypes were identified. High rate of resistance was identified against nalidixic acid (82.85%), amoxicillin (81.25%), streptomycin (75%), and ciprofloxacin (75%). Alarming level of resistance to ertapenem (12.5%) was noticed. A total of 87.5% (56/64) of isolated strains were recognized as MDR. Three MDR strains were extended-spectrum β-lactamases (ESBL)-producers and three MDR strains were cephalosporinase-producers. The gene was amplified in all the three ESBL strains. The gene was not amplified in fluoroquinolones-resistant strains. The and genes were amplified in 5% (2/40) and 2.5% (1/40) of tetracycline-resistant strains, respectively. The gene was amplified in five of the 20 trimethoprim-resistant strains. The and genes were not amplified in any of the phenotypically colistin-resistant strains. In terms of integrase genes int1 and int2, only gene class 2 was amplified in 11% (7/64) of analyzed strains. Risk factors, such as the poor level of cleaning and disinfection, the lack of antimicrobial treatment at the start of the breeding, and a crawl space duration lower than 15 days, were associated with high infection in birds. These data should be considered when preparing salmonellosis control programs in Tunisian broiler flocks.