The molecular epidemiology of Salmonella Typhi across Indonesia reveals bacterial migration

Abstract

BACKGROUND: Typhoid fever remains a worldwide problem, but it is particularly common in Southeast Asia, including Indonesia. The causative agent Salmonella Typhi is known to have significant genome plasticity. METHODOLOGY: This study describes genetic fingerprints using restriction fragment length polymorphism with SpeI of chromosomal DNA and pulsed-field gel electrophoresis (PFGE) of S. Typhi isolated from different geographic areas spreading from west to east across Indonesia. RESULTS: A total of 33 SpeI digested S. Typhi chromosomal DNA gave 22 schizotypes, 20 pulsotypes, and 12 subtypes indicating genomic diversity and the presence of more than one clone of S. Typhi. Cluster analysis at a degree of similarity of ≥80% showed four clusters, three of which were associated with geographic area. One cluster (Dice coefficient 0.727-1.000) contained isolates from three different geographic areas (Jakarta, Makasar, Jayapura), spread across Indonesia. CONCLUSIONS: Genetic fingerprinting of S. Typhi in Indonesia showed the presence of endemic strains in localized geographic areas, as well as the movement of one strain type throughout the archipelago.