Abstract
BackgroundCambodia 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.MethodsWe 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).ResultsClassical 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.ConclusionsThe 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.
Highlights
Cambodia is among the 22 high-burden TB countries, and has one of the highest rates of TB in South-East Asia
We report in this article the characterization of this 118 clinical isolates collection as a first insight on the genetic population structure of Mycobacterium tuberculosis complex (MTC) in Cambodia
Spoligotyping, classical 43 spacers format M. tuberculosis complex clinical isolates were collected from 118 patients
Summary
Cambodia is among the 22 high-burden TB countries, and has one of the highest rates of TB in South-East Asia. The largest number of new TB cases occurs in the South-East Asian Region, that accounted for 34% of incident cases in 2006 [2]. Cambodia is among the 22 high-burden TB countries, and has one of the highest rates of TB in South-East. The population of Cambodia is 13.4 million (Population Census of 2008). The new sputum smear positivity rate for Cambodia is estimated to be 220/ 100,000 inhabitants whereas the TB incidence is estimated around 500/100,000 inhabitants per year and the mortality rate at 94/100,000 inhabitants [4]. PhnomPenh is the capital of Cambodia, with more than 1.3 million inhabitants (Population Census of 2008), which represents 10% of the whole population living in the country. The population density of Phnom-Penh is the highest of the country, with around 4,500 people per km
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