Molecular Epidemiology of Sporadic and Outbreak-Related Salmonella Typhi Isolates in the Brazilian North Region: A Retrospective Analysis from 1995 to 2013.

Typhoidal salmonellosis is a global public health problem occurring in developing endemic regions. In Brazil, cases are mostly registered in the North and Northeast regions. Molecular characterization of the strains is important to understand the epidemiology of disease infections and to design control strategies. The present study retrospectively evaluates the genotyping features of sporadic and outbreak-related Salmonella Typhi isolates from the Brazilian North region. Bacterial isolates were recovered from blood and a rectal swab of patients in the states of Acre and Pará, Brazilian North region, in the period of 1995 to 2013, and were submitted to genotyping by applying Multilocus sequence typing (MLST) and Pulsed Field Gel Electrophoresis (PFGE) reference methods. MLST genotyping revealed the presence of epidemic clones ST1 and ST2, and 20 pulsotypes were identified by PFGE, including four distinct clusters (A-D), and six subclusters (A1-D1) with indistinguishable strains in different periods and locations. To conclude, the obtained data demonstrates the temporal stability, adaptation, and transmission of outbreak-related and sporadic S. Typhi strains over time, contributing to the transmission chain in the region.