Emergence of multidrug-resistant clones of Salmonella Infantis in broiler chickens and humans in Hungary.

OBJECTIVES The characterization of a Salmonella Infantis strain collection that was set up from isolates of animal and human origin obtained in Hungary in recent years. METHODS All isolates were phage typed. Antimicrobial resistance was tested by the disc diffusion method, while the presence of the antimicrobial resistance genes and class 1 integrons was investigated by PCR. Genetic relatedness of the isolates was tested by PFGE and plasmid profiling. RESULTS The majority of the isolates representing different parts of Hungary are characterized by phage types 213 and 217 and the nalidixic acid-streptomycin-sulphonamide-tetracycline resistance type. They harbour a class 1 integron with an aadA1 gene in the 855 bp variable region, a tet(A) gene, a >168 kb plasmid and 66% of them represent one genetic clone as determined by XbaI PFGE fingerprinting. CONCLUSIONS It seems that broiler chickens constitute a reservoir for one large and a few smaller multidrug-resistant Salmonella Infantis clones in Hungary, which might have spread to humans through chicken meat.