Trilocus Sequence Typing (TLST) Of Campylobacter jejuni (#203)
Campylobacter jejuni has been recognized as the most common bacterial cause of gastroenteritis worldwide since the late 1970s. In Victoria, Australia, only 12% of campylobacter isolates were subtyped in 2007, and only 1-3 outbreaks caused by C. jejuni were detected annually from 2002 to 2007. This is despite the number of annual notified number of cases being more than 6000, suggesting that the campylobacter surveillance system in Victoria is not fully satisfying its objectives . Bacterial typing plays important role in epidemiological surveillance of C. jejuni infections to trace the source and route of transmission. Among genotyping methods, sequence based methods are preferred for unambiguous data production, ease of data transfer, reliability, reproducibility and discriminatory power. In this study, we present a trilocus sequence typing (TLST) scheme based on the intragenic sequence of porA (associated with antibiotic resistance), peb1A (virulence factor by dual role of adhesin and solute binding protein) and mapA (membrane associated protein) genes for typing or subspecies differentiation of C. jejuni. Each of the three alleles was analysed using 50 C. jejuni strains from variety of sources such as human, chicken, water, ovine and canine, which included 10 outbreak strains and 33 epidemiologically unrelated strains. Multiple DNA sequence alignment was used to identify porA,peb1A and mapA allelic types. The allelic profiles of the concatenated sequences of the three genes (1253 bp) differentiated 33 epidemiologically unrelated strains into 27 types with resulting discriminatory power of 0.986. The newly developed TLST scheme generated comparable results to multilocus sequence typing (MLST) results while being a rapid and low cost sequence based typing scheme for C. jejuni.