Antibiotic Resistance and Molecular Studies on Salmonella Enterica Subspecies Enterica Serovar Infantis Isolated in Human Cases and Broiler Carcasses

During the year 2012 a study was conducted on the hygiene of the production of broiler carcasses at three abattoirs in the Republic of Serbia. A total of 150 samples of broiler neck skin were examined and 17 salmonella isolates were recorded. Isolates were, by using the corresponding monovalent and polyvalent sera, determined according to type as Salmonella enterica subspecies enterica serovar Infantis (S. Infantis 6, 7, r, 1, 5). In the case of the disease in humans, 5 Salmonella samples of identical serovars were isolated. After that, 22 samples were tested for antibiotic resistance by the disk diffusion test. Isolates showed resistance to ampicillin and nalidixic acid (95.5%), tetracycline (91%), cefotaxime/clavulanic acid (68.2%), but not to ciprofloxacin, gentamicin, and trimethoprim/sulfamethoxazole. The degree of genetic similarity of isolates from diseased humans and broiler carcasses was determined at a molecular level. Cluster analysis revealed the presence of 7 profiles, while all isolates have 92% genetic similarity. Although there are differences in the antimicrobial resistance of isolates originating from diseased humans and neck skin of tested broilers, can not be excluded an epidemiological link, because in the dominant genotype SINFXB0001, established in 8 isolates from diseased humans (3 isolates), and the neck skin of broilers (5 isolates), a genetic similarity of 100% was recorded. Based on these results, the presence of S. Infantis on broiler carcasses can be considered a hazard to human health.