Molecular Analysis Of Salmonella Enterica Serovar Typhi Isolates Using Pulsed-Field Gel Electrophoresis; Comparison Between Acute And Carriers Of Typhoid Fever
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Date
2011-05
Authors
Kamaruzzaman, Nor Fadhilah
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Publisher
Universiti Sains Malaysia
Abstract
Typhoid fever is a systemic disease caused by S.Typhi, a Gram negative bacterium that infects exclusively humans. The disease is endemic in Kelantan, which has the highest incidence in Malaysia. Despite the endemicity, not much information is known regarding the type of S.Typhi strains and its distribution in this region. Thus, this study was conducted to ascertain retrospectively the genetic diversity and distribution of S.Typhi strains isolated from patients with acute typhoid, asymptomatic carriers and environmental samples in Kelantan, between the year 2002 and 2009. Molecular epidemiology study was carried out using Pulsed-Field Gel Electrophoresis (PFGE) method to characterize 264 individual S.Typhi isolates available in this study. A total of 260 S.Typhi isolates were successfully typed by PFGE using XbaI restriction enzyme, and 38 strains were found, which were designated as X001 to X038.
The 5 most common strains were X001, X002, X009, X011 and X037 that accounted for 76.5% of the total isolates. The predominant strain was X001 (44%), which was consistently found in every year and in every district, and was the same strain that caused a major outbreak in 2005. Thus, this strain was considered as the endemic strain due to its ability to persist in this region. PFGE analysis of S.Typhi isolated from carriers showed the same strains distributed amongst the isolates from patients with acute infection, indicating that there was no genomic difference between them that could be identified by the PFGE method. PFGE analysis performed on isolates from environmental samples uncovered a strain that was also found in 2 isolates from patients with acute typhoid infection, proved the ability of S.Typhi to survive in the environment and cause infection in humans.
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Keywords
The genetic diversity and distribution of S.Typhi strains , isolated from patients with acute typhoid