Búsqueda del plásmido de virulencia de Salmonella en aislamientos clínicos colombiano

introduction: salmonella is a gram negative bacillus, intracellular pathogen that invades nonphagocytic intestinal cells and macrophages in a complex process that requires multiple genes. the salmonella virulence plasmid "spv" contains the spvr gene whose function is to increase its virulence producing systemic invasion in mice. methods: we search for spvr gene in human clinical isolates of salmonella spp from patients with systemic infection (typhoid fever) and with nonsystemic infection (diarrheal), in order to compare the presence of the gene to clinical outcome. spvr was searched in 55 clinical isolates of s. typhi from typhoid fever patients, 20 of s. enteritidis and 20 of s. typhimurium isolates from patients with diarrheal. pcr from chromosomal and plasmid dna was performed. the pcr products were sequenced and the sequences obtained from genomic and plasmid materials were compared using bioinformatics analysis. results: 55 (100 %) isolates of s. typhi were negative for spvr. 15 (75 %) isolates of s. enteritidis and 8 (40 %) of s. typhimurium were positive for spvr both from genomic and plasmid material. these results show that clinical isolates of s. typhi considered more virulent not showed spvr, and that diarrhea-producing serotypes s. enteritidis and s. typhimurium in 75 and 40 % respectively were positive for the gene, questioning the role of virulence of the gene in strains producing human infections. it also showed the presence of plasmid gene sequences homologous to chromosomal regions in the studied serotypes. conclusion: results show that the absence of the plasmid of salmonella's virulence is not related with the systemic outcome in the clinical isolates of salmonella typhi that were studied. there was also confirmed that exists chromosomal material homologous to the gene spvr virulence plasmid in the chromosome of serotypes s. enteritidis and s. typhimurium but similar material wasn't found in s. typhi chromosome.