Antibiotic resistance of Salmonella spp. isolates from pigs in the Czech Republic

A total of 126 Salmonella spp. isolates from pigs belonging to 13 serotypes (Typhimurium, Derby, Infantis, Enteritidis, Agona, Kaapstad, London, Montevideo, Bredeney, Give, Oritamerin, Schwarzengrund and Tennessee) were tested for sensitivity to 14 antibiotics. Resistance to 1-8 antibiotics was demonstrated in 64 isolates (59.8%), classified into seven serotypes with the most frequent being Salmonella typhimurium (n = 54). S. typhimurium strains were found to be the most resistant to streptomycin (91.5%), sulphonamides (88.1%), ampicillin (86.4%), tetracycline (84.7%) and chloramphenicol (83.0%), displaying the ACSSuT phenotype. In all strains of this phenotype (n = 27), the gene for integrase (int1) and resistance genes bla(PSE-1),floR, aadA2, sul1 and tetG were detected by PCRs. In some of the strains, additional resistance to amoxycillin/clavulanic acid, sulphamethoxazole/trimethoprim, nalidixic acid and enrofloxacin was found.