Previous Article | Next Article ![]()
Journal of Clinical Microbiology, July 2006, p. 2553-2557, Vol. 44, No. 7
0095-1137/06/$08.00+0 doi:10.1128/JCM.00629-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,1 Center for Clinical Vaccinology and Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom,2 The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom,3 Menzies School of Health Research, Charles Darwin University, Darwin, Australia,4 Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom,5 Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom6
Received 23 March 2006/ Returned for modification 13 April 2006/ Accepted 14 April 2006
Burkholderia pseudomallei is a soil-dwelling saprophyte and the causative agent of melioidosis, a life-threatening human infection. Most cases are reported from northeast Thailand and northern Australia. Using multilocus sequence typing (MLST), we have compared (i) soil and invasive isolates from northeast Thailand and (ii) invasive isolates from Thailand and Australia. A total of 266 Thai B. pseudomallei isolates were characterized (83 soil and 183 invasive). These corresponded to 123 sequence types (STs), the most abundant being ST70 (n = 21), ST167 (n = 15), ST54 (n = 12), and ST58 (n = 11). Two clusters of related STs (clonal complexes) were identified; the larger clonal complex (CC48) did not conform to a simple pattern of radial expansion from an assumed ancestor, while a second (CC70) corresponded to a simple radial expansion from ST70. Despite the large number of STs, overall nucleotide diversity was low. Of the Thai isolates, those isolated from patients with melioidosis were overrepresented in the 10 largest clones (P < 0.0001). There was a significant difference in the classification index between environmental and disease isolates (P < 0.001), confirming that genotypes were not distributed randomly between the two samples. MLST profiles for 158 isolates from Australia (mainly disease associated) contained a number of STs (96) similar to that seen with the Thai invasive isolates, but no ST was found in both populations. There were also differences in diversity and allele frequency distribution between the two populations. This analysis reveals strong genetic differentiation on the basis of geographical isolation and a significant differentiation on the basis of virulence potential.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»