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

Abstract 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. Abstract Tokom 2012. godine sprovedena su istraživanja higijene procesa proizvodnje trupova brojlera, na tri klanice u Republici Srbiji. Ispitano je 150 uzoraka kožica vrata brojlera i utvrđeno je 17 izolata salmonela. Izolati su, korišćenjem odgovarajućih monovalentnih i polivalentnih seruma, tipizovani kao Salmonella enterica subspecies enterica serovar infantis (S. Infantis 6, 7, r, 1, 5). U slučajevima oboljenja ljudi, izolovano je 5 uzoraka salmonele identičnog serovarijeteta. Nakon toga, na 22 uzorka, rađeno je ispitivanje antibiotske rezistencije izolata disk difuzionim testom. Izolati su pokazali rezistentnost prema: ampicilinu i nalidiksičnoj kiselini (95,5%), tetraciklinu (91%), cefotaksim/klavulanskoj kiselini (68,2%), ali ne i prema ciprofloksacinu, gentamicinu i trimetoprim/sulfametoksazolu (0%). Stepen genetske sličnosti izolata poreklom od obolelih ljudi i sa trupova brojlera je određen molekularnim metodama. Analiza klastera je pokazala prisustvo 7 profila, dok svi izolati imaju 92% ge netske sličnosti. Iako postoje razlike u antimikrobnoj rezistenciji izolata poreklom od obolelih ljudi i sa kožica vrata brojlera, ne može se isključiti epidemiološka povezanost, jer kod dominantnog genotipa SINFXB0001, utvrđenog kod 8 izolata poreklom od obolelih ljudi (3 izolata) i sa kožica vrata brojlera (5 izolata), postoji genetska sličnost od 100%. Na osnovu dobijenih rezultata, istraživanje je pokazalo da prisustvo S. Infantis na trupovima brojlera predstavlja hazard po zdravlje ljudi.