Molecular epidemiology of the endemic multiresistance plasmid pSI54/04 of Salmonella Infantis in broiler and human population in Hungary.

Salmonella Infantis (SI) became endemic in Hungary where the PFGE cluster B, characterized by a large multiresistance (MDR) plasmid emerged among broilers leading to an increased occurrence in humans. We hypothesized that this plasmid (pSI54/04) assisted dissemination of SI. Indeed, Nal-Sul-Tet phenotypes carrying pSI54/04 occurred increasingly between 2011 and 2013 among SI isolates from broilers and humans. Characterization of pSI54/04 based on genome sequence data of the MDR strain SI54/04 indicated a size of ∼277 kb and a high sequence similarity with the megaplasmid pESI of SI predominant in Israel. Molecular characterization of 78 representative broiler and human isolates detected the prototype plasmid pSI54/04 and its variants together with novel plasmid associations within the emerging cluster B. To test in vitro and in vivo pathogenicity of pSI54/04 we produced plasmidic transconjugant of the plasmid-free pre-emergent strain SI69/94. This parental strain and its transconjugant have been tested on chicken embryo fibroblasts (CEFs) and in orally infected day old chicks. The uptake of pSI54/04 did not increase the pathogenicity of the strain SI69/94 in these systems. Thus, dissemination of SI in poultry could be assisted by antimicrobial resistance rather than by virulence modules of the endemic plasmid pSI54/04 in Hungary.

Genome Sequences of Salmonella enterica subsp. enterica Serovar Infantis Strains from Hungary Representing Two Peak Incidence Periods in Three Decades.

Four strains of Salmonella enterica subsp. enterica serovar Infantis isolated from humans (1980 to 1982) and broiler chickens (2016) have been sequenced. They represent the early and recent peak incidences of this serovar in Hungary. Genome sequences of these isolates provide comparative data on the evolution and rise of an endemic S Infantis clone in Hungary.

Genome Sequences of Multidrug-Resistant Salmonella enterica subsp. enterica Serovar Infantis Strains from Broiler Chicks in Hungary.

Three strains of Salmonella enterica serovar Infantis isolated from healthy broiler chickens from 2012 to 2013 have been sequenced. Comparison of these and previously published S Infantis genome sequences of broiler origin in 1996 and 2004 will provide new insight into the genome evolution and recent spread of S Infantis in poultry.

Genome Sequences of Three Salmonella enterica subsp. enterica Serovar Infantis Strains from Healthy Broiler Chicks in Hungary and in the United Kingdom.

The genome sequences of three strains of Salmonella enterica subsp. enterica serovar Infantis isolated from broiler chickens in 1994 and 2004 in Hungary and in the 1980s in the United Kingdom are reported here. A sequence comparison should improve our understanding of the evolution of the genome and spread of S. Infantis in poultry.