Molecular and pathogenic characterization of Salmonella enterica serovar Bovismorbificans strains of animal, environmental, food, and human origin in Hungary.

In this study, we characterized 110 strains of Salmonella enterica serovar Bovismorbificans contaminating environment, animals, food of animal origin, and human, to assess their significance along the food chain in Hungary. Additionally, five strains from Germany were tested for comparative purposes. Characterization involved antibiotic susceptibility testing, class 1 integron detection by polymerase chain reaction, plasmid profiling, virulotyping (using virulence gene-specific polymerase chain reactions), and pulsed-field gel electrophoresis. Pathogenic potential of selected strains was tested in orally infected 1-day-old specific pathogen-free chicks. Eighty-two percent of the strains were susceptible to the 16 antibiotics tested, and none of them had class 1 integron. A multidrug-resistant human isolate harbored a bla(SHV5)-type extended-spectrum beta-lactamase gene, first reported in this serotype. All the strains possessed avrA, ssaQ, mgtC, spi4, and sopB genes indicating the presence of Salmonella pathogenicity islands 1-5, respectively, missed the phage-related genes sopE and gipA, but retained the phage-related gene sodC1. An approximately 90 kb large plasmid was characteristic to 80% of the strains, all of which carried the spvC gene. In vivo colonization testing of four selected strains in 1-day-old chicks resulted in significantly reduced liver and spleen colonization ability as compared with the Salmonella Enteritidis control strain, whereas their caecal colonization ability differed less from that of Salmonella Enteritidis. Pulsed-field gel electrophoresis data revealed the dominance of two pulsotypes (C2 and C5) without any specific temporal, geographical, and/or source-related linkages. The results show that Salmonella Bovismorbificans studied here are less invasive than Salmonella Enteritidis, but they may colonize and persist in several animal species and successfully contaminate meat products of different animal origin in Hungary.

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.