Molecular phylogenetic approach for classification of Salmonella typhi

Abstract

Salmonella typhi causes a severe systemic illness through intake of contaminated food or water containing bacterium. This kind of pathogen is still residing in asymptomatic carriers which may be considered as a sole source for the outbreak. Thus, the aim of the present investigation was to identify the Salmonella typhi strains isolated from asymptomatic typhoid carriers. The cultural characteristics on BSA, Macconkey agar and XLD were used for S. typhi identification. The OmpR gene regions of these strains were amplified and sequenced. The Maximum Parsimony algorithm tree of OmpR was constructed using max-mini branch and bound model. The OmpR gene sequences were used for finding similarities and genetic distances with other related bacterial species. The results of similarity and genetic distance analyses were further used for statistical and cluster analyses. The two strains were designated as SS3 and SS5. Both strains were identified as S. typhi on the basis of biochemical, phylogenetic, comparative and statistical analyses. Thereby, we conclude that gene such as OmpR might be more useful for identifying bacteria at even in species level. However, use of entire genomic sequences is more accurate yet it is more expensive and time consuming process. © 2012 Academic Journals Inc.