Analysis of Salmonella enterica Serovar Typhi by Outer Membrane Protein (OMP) Profiling, Random Amplification of Polymorphic DNA (RAPD) and Pulsed Field Gel Electrophoresis (PFGE)

Yashwant Kumar,Kavaratty Raju Mani,Ajay Kumar Tahlan

doi:10.21315/tlsr2019.30.1.4

Abstract

A number of countries, including developed countries, still have typhoid fever as a major problem resulting in frequent outbreaks. The importance of controlling spread of typhoid fever is well known and necessitates periodic studies to delineate epidemiological relationships. Although phage typing remains to be the preferred conventional method for characterisation of typhoid bacilli, it is of limited use due to prevalence of few predominant phage types in the country like India. Therefore, an effort has been made to assess three molecular methods [Outer Membrane Protein (OMP) Profiling, Random Amplification of Polymorphic DNA (RAPD) and Pulsed Field Gel Electrophoresis (PFGE)] for typing of Salmonella enterica serovar Typhi. 128 Salmonella enterica serovar Typhi isolates were identified using biotyping and serotyping followed by antimicrobial susceptibility testing. These isolates were further subjected to OMP analysis, RAPD and PFGE. PFGE (114 unique clusters) was found to be the most discriminatory method followed by RAPD (94 unique clusters) and OMP profiling (50 unique clusters). Multidrug resistant strains were well discriminated by all three methods used in the study. PFGE still remains the most preferred method for detailed epidemiological investigations. However, random amplification of polymorphic DNA and outer membrane protein profiling can also be considered for molecular discrimination of the isolates in the laboratories lacking high-end facilities.

Highlights

Salmonella serovars are responsible for infections occuring in developing as well as developed world and have been a major concern in terms of economic burden due to high morbidity (Obaro et al 2017)
When 128 isolates, received from various parts of India, were analysed using Outer Membrane Protein (OMP) profiling, Random Amplification of Polymorphic DNA (RAPD) and Pulsed Field Gel Electrophoresis (PFGE), outer membrane protein profiling was able to cluster 128 strains of Salmonella enterica serovar Typhi into 50 unique groups (Fig. 1) whereas RAPD and PFGE were able to group them into 94 unique groups (Fig. 2) and 114 unique groups (Fig. 3) respectively
Considering the present scenario commanded by the emergence and spread of multidrug resistance among Salmonella enterica serovar Typhi in addition to high morbidity and mortality associated with typhoid, continuous surveillance using various epidemiological tools is required

Summary

Introduction

Salmonella serovars are responsible for infections occuring in developing as well as developed world and have been a major concern in terms of economic burden due to high morbidity (Obaro et al 2017). Salmonella enterica serovar Typhi leads to infections in children and adults resulting in high morbidity (Paul & Bandyopadhyay 2017). Epidemiological investigation of Salmonella enterica serovar Typhi becomes relevant, primarily in the endemic areas which will facilitate delineation of distribution and transmission patterns of the strains and help health authorities to revise and establish effective prophylactic and therapeutic strategies. Various conventional phenotypic methods comprising biotyping, serotyping, phage typing and antimicrobial susceptibility testing, are being used frequently for epidemiological investigations. These methods lay down the basis of phenotypic characterisation of the isolates, these are unable to provide enough epidemiological information. Serotyping, being the most widely used phenotypic method, fails to provide appropriate information due to complex serotyping scheme and lack of comparison among different laboratories thereby limiting its application to the reference laboratories only (Parmley et al 2013)

Methods

Results

Discussion

Conclusion