Genotypic diversity, pathogenic potential and the resistance profile of Salmonella Typhimurium strains isolated from humans and food from 1983-2013 in Brazil.
J Med Microbiol. 2015 Aug 24;
Authors: Almeida F, Medeiros MI, Rodrigues DD, Falcao JP
Salmonella Typhimurium is one of the leading serovars that causes salmonellosis worldwide. However, few studies have molecularly characterised S. Typhimurium strains in Brazil. In this study, we genotyped 92 S. Typhimurium strains isolated from humans(43) and food(49) between 1983-2013 in Brazil using PFGE, MLVA and ERIC-PCR. Moreover, we assessed the frequency of 12 virulence markers by PCR and the resistance profile against 12 antimicrobials. More than 85.8% of the strains studied carried 11 of the virulence markers or more. Thirty-three (25%) strains were multi-drug resistant (MDR). The 92 S. Typhimurium studied were grouped by PFGE in PFGE-A, PFGE-B1 and PFGE-B2; by MLVA in MLVA-A, MLVA-B1 and MLVA-B2 and, finally, were grouped by ERIC-PCR in ERIC-A and ERIC-B. The strains isolated from humans before the mid-1990s were allocated in all clusters. The strains isolated from humans after the mid-1990s were distributed in the PFGE-B1, MLVA-B1, MLVA-B2 and ERIC-A clusters. The strains isolated from food were distributed in all clusters, except in the PFGE-B2. All typing results suggest that the S. Typhimurium strains of human clinical origin isolated before the mid-1990s were genetically more diverse, which might indicate the selection of a more adapted S. Typhimurium subtype after S. Enteritidis became the most prevalent serovar in Brazil. Regarding strains isolated from food, the results suggest the current circulation of more than one subtype. Furthermore, the high frequency of virulence genes and the presence of MDR strains reinforces their potential hazard for humans and the risk of their presence in foods in Brazil.
PMID: 26307078 [PubMed - as supplied by publisher]