Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2017

Genomics of tuberculosis transmission in TB/HIV co-infected patients in Vietnam (#38)

Mai Q Trinh 1 2 3 , Elena Martinez 2 3 , Van Anh T Nguyen 1 , Ben J Marais 2 , Vitali Sintchenko 2 3
  1. National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
  2. Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, NSW, NEW SOUTH WALES, Australia
  3. NSW Mycobacterium Reference Laboratory, Centre for Infectious Disease and Microbiology, ICPMR-Pathology West, Westmead Hospital, Sydney, New South Wales, Australia

Background

Vietnam ranked 15th among high-burden tuberculosis (TB) countries and 16th among high-burden Multi Drug Resistant-TB (MDR-TB) countries in the world. The management of TB/HIV co-infected patients presents challenges to TB control but our understanding of their contribution to TB transmission and development of drug resistance remains limited.

Objective

To examine genomic polymorphisms in MDR-TB isolates and transmission of M. tuberculosis within the population of TB/HIV co-infected patients in Vietnam.

Method

200 M. tuberculosis isolates from a cohort of TB/HIV co-infected patients diagnosed and managed between 2009 and 2014 at the main HIV referral hospital in Ho Chi Minh City were studied. Phenotypic drug susceptibility testing (DST) was performed for four first line drugs. Mycobacterium Interspersed Repeat Unit (MIRU)-24 profiles were examined for all isolates; and clusters and phylogenetic lineages identified. MDR-TB isolates and MIRU-24 clusters were further assessed using whole genome sequencing (WGS).

Results

The rate of MDR-TB was 8.5%; with 5% resistance against all drugs tested. Beijing (49%) and East African Indian (EAI) lineage strains (35%) were most common. The overall rate of MIRU-24 clustering was 20% with 16 clusters (2-4 isolates per cluster). Beijing lineage strains were the most common among clustered cases (68.7%). Application of WGS enabled the reduction of clusters from 16 to 3, with only 2 isolates per cluster. Most clusters defined by MIRU presented a range of SNPs from 20 to 238, showing the lower resolution power of MIRU-24 over WGS. Limited M. tuberculosis transmission within community of TB/HIV co-infected patients was observed. Beijing lineage was dominant among MDR isolates from TB/HIV co-infected patients, with higher pattern of resistance compared with EAI lineage. Mutations responsible for drug resistance genotype were also characterised.

Conclusions

Local transmission within communities of TB/HIV co-infected patients in Vietnam appears to be limited and TB transmission between HIV-infected and naïve populations are more likely. The emergence of MDR-TB in Beijing strains can affect the delivery of TB control programs.