Prevalence and genetic basis of first line drug resistance of M. tuberculosis in Ca Mau, Vietnam

Abstract

Background: Data on the prevalence of anti-tuberculous drug resistance and its association with genetic mutations in Mycobacterium tuberculosis are limited.

Methods: Patients ≥15 years in Ca Mau Province, Vietnam, were screened annually for tuberculosis between 2014 and 2017. Isolates underwent direct susceptibility testing (DST) using the breakpoint method. DNA was extracted and whole genome sequencing (WGS) was performed.

Results: We identified 365 positive sputum cultures for M tuberculosis and processed 237 for DST and 265 for WGS. Resistance to isoniazid was present in 19.8% (95%CI 14.7%–24.9%), rifampicin in 3.5% (1.1%–5.7%) and ethambutol in 2.5% (0.9%–5.4%) of isolates. Relevant mutations in rpoB gene were detected in 3.8% (1.8%–6.8%). katG, inhA or fabG1 mutations were found in 19.6% (15.0%–24.9%) with KatG being most common at 12.8% (9.1%–17.5%). We found 38.4% of isolates were of Beijing lineage, 49.4% East-African-Indian lineage and 8.4% European-American lineage. There were no associations between resistance profiles and clinical features.

Conclusion: The high burden of isoniazid resistance and the katG mutation highlights the challenges facing Vietnam in its effort to achieve its EndTB goals.

Key Words: tuberculosis, prevalence, mutations, resistance, treatment.

Nomination for New Investigator Award: Janet Elder International Travel Award.

Grant Support: Nil.