Plasmid profiling and comparison of the plasmid profiles with virulence of Indian Salmonella Typhimurium strains of varied origin

Among 2,668 Salmonella enterica serovars Salmonella Typhimurium is the most common serovar and discrimination of isolates within this serovar is necessary for the effective epidemiological surveillance and control. Plasmid profiling is an efficient tool for discrimination of bacterial isolates. Hence, 22 strains of S. Typhimurium isolated from different parts of India were analyzed by plasmid profiling to check its differentiation power and to correlate the results with virulence. Nine different sized bands were detected after plasmid isolation with 90.0 kb band shared by most isolates. At least one plasmid was present in all isolates. Based on plasmid profiles 22 isolates were classified into 10 groups with a discriminating power of 0.89. The maximum dissimilarity distance was 0.96496 units. No remarkable correlation between plasmid pattern and host origin could be established pointing out the potential hazard of interspecies sharing. However, comparison of plasmid profiles with virulence revealed the absence of 90.0 kb plasmid in non virulent isolates. The present study thus confirmed the potential discriminatory power of plasmid profiling along with extraordinarily high incidence of plasmids among Indian S. Typhimurium isolates. Additionally it indicated the presence of 90 kb plasmid to be used as a virulence marker of this serovar.