Molecular Epidemiology of Zoonotic Salmonella Enteritidis Isolated from Poultry and Human Sources by Multi Locus Sequence Typing

Salmonella enterica, sub specie enterica, serovar Enteritidis is still one of the major zoonotic serotypes responsible for infection in poultry and humans worldwide. For the tracking of bacterial sources and to determine the distribution of Salmonella from infected people, typing technologies are highly essential. Multilocus sequence typing is one of the subtyping techniques based on sequencing of three to seven well conserved housekeeping genes within the bacterial genome. It is a valuable tool for exploring the genetic diversity of known serovars and the identification of genetic clusters of Salmonella. The present study was conducted in Lahore from January 2019 to June 2019. A total of 320 samples were collected from poultry (n=250) and human sources (n=70). Salmonella was phenotypically confirmed by biochemical tests and molecularly by targeting the ompc gene for genus and sdf1 gene for serovar Enteritidis. MLST was performed on three Salmonella Enteritidis, and three untyped isolates. All the S. Enteritidis isolates fall in ST (11) with eBG4. MLST identified the untyped isolates as Salmonella Infantis (ST 32), Salmonella Agona (ST13), and Salmonella Brederny (ST505). The results of MLST showed the clonal relationship between S. Enteritidis isolated from poultry and human sources. MLST scheme resulted in total of 4 ST's with all S. Enteritidis fall in (ST 11). Phylogenetic analysis revealed the same genetic lineage between all S. Enteritidis and a different lineage for other isolated serovars. In conclusion the results of present study suggested that MLST can be used as a subtyping technique to find out clonal relationship between seovars and can also be used as alternative method for serotyping of Salmonella. (C) 2020 PVJ. All rights reserved