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Open Access Research article

A first assessment of the genetic diversity of Mycobacterium tuberculosis complex in Cambodia

Jian Zhang1, Seiha Heng2, Stéphanie Le Moullec1, Guislaine Refregier1, Brigitte Gicquel3, Christophe Sola13* and Bertrand Guillard2

  • * Corresponding author: Christophe Sola csola@pasteur.fr

  • † Equal contributors

Author Affiliations

1 Institut de Génétique et Microbiologie, UMR8621 CNRS-Université Paris-Sud 11, UniverSud, Infection Genetics Emerging Pathogens Evolution (IGEPE) Team, Bât. 400, F-91405 Orsay-Cedex, France

2 Institut Pasteur du Cambodge, Phnom-Penh, 5 boulevard Monivong, BP 983, Phnom-Penh, Royaume du Cambodge

3 Unité de Génétique Mycobactérienne, Institut Pasteur, Paris, France

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BMC Infectious Diseases 2011, 11:42  doi:10.1186/1471-2334-11-42

Published: 7 February 2011

Abstract

Background

Cambodia is among the 22 high-burden TB countries, and has one of the highest rates of TB in South-East Asia. This study aimed to describe the genetic diversity among clinical Mycobacterium tuberculosis complex (MTC) isolates collected in Cambodia and to relate these findings to genetic diversity data from neighboring countries.

Methods

We characterized by 24 VNTR loci genotyping and spoligotyping 105 Mycobacterium tuberculosis clinical isolates collected between 2007 and 2008 in the region of Phnom-Penh, Cambodia, enriched in multidrug-resistant (MDR) isolates (n = 33).

Results

Classical spoligotyping confirmed that the East-African Indian (EAI) lineage is highly prevalent in this area (60%-68% respectively in whole sample and among non-MDR isolates). Beijing lineage is also largely represented (30% in whole sample, 21% among non-MDR isolates, OR = 4.51, CI95% [1.77, 11.51]) whereas CAS lineage was absent. The 24 loci MIRU-VNTR typing scheme distinguished 90 patterns with only 13 multi-isolates clusters covering 28 isolates. The clustering of EAI strains could be achieved with only 8 VNTR combined with spoligotyping, which could serve as a performing, easy and cheap genotyping standard for this family. Extended spoligotyping suggested relatedness of some unclassified "T1 ancestors" or "Manu" isolates with modern strains and provided finer resolution.

Conclusions

The genetic diversity of MTC in Cambodia is driven by the EAI and the Beijing families. We validate the usefulness of the extended spoligotyping format in combination with 8 VNTR for EAI isolates in this region.