Drug resistance and the genotypic characteristics of rpoB and katG in rifampicin- and/or isoniazid-resistant Mycobacterium tuberculosis isolates in central Vietnam

Thi Binh Nguyen Nguyen; Thi Kieu Diem Nguyen; Van Hue Trương; Thi Tuyet Ngoc Tran; van Bao Thang Phan; Thi Tuyen Nguyen; Hoang Bach Nguyen; Viet Quynh Tram Ngo; Van Tuan Mai; Paola Molicotti

doi:10.24171/j.phrp.2023.0124

Drug resistance and the genotypic characteristics of rpoB and katG in rifampicin- and/or isoniazid-resistant Mycobacterium tuberculosis isolates in central Vietnam

Osong Public Health Res Perspect. 2023 Oct;14(5):347-355. doi: 10.24171/j.phrp.2023.0124. Epub 2023 Oct 18.

Affiliations

¹ Department of Infectious Diseases and Tuberculosis, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam.
² Da Nang Lung Hospital, Da Nang, Vietnam.
³ Central Hospital 71, Thanh Hoa, Vietnam.
⁴ Department of Microbiology, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam.
⁵ Department of Microbiology, Hue Central Hospital, Hue, Vietnam.
⁶ Department of Biomedical Science, Microbiology and clinical Microbiology, University of Sassari, Sassari, Italy.

Abstract

Background: Tuberculosis (TB) and drug-resistant TB (DR-TB) are national health burdens in Vietnam. In this study, we investigated the prevalence of rifampicin (RIF) and/or isoniazid (isonicotinic acid hydrazide, INH) resistance in patients with suspected TB, and applied appropriate techniques to help rapidly target DR-TB.

Methods: In total, 1,547 clinical specimens were collected and cultured using the BACTEC MGIT system (Becton Dickinson and Co.). A resazurin microtiter assay (REMA) was used to determine the proportions of RIF and/or INH resistance. A real-time polymerase chain reaction panel with TaqMan probes was employed to identify the mutations of rpoB and katG associated with DR-TB in clinical isolates. Genotyping of the identified mutations was also performed.

Results: A total of 468 Mycobacterium tuberculosis isolates were identified using the REMA. Of these isolates, 106 (22.6%) were found to be resistant to 1 or both antibiotics. Of the resistant isolates, 74 isolates (69.8%) were resistant to isoniazid (INH) only, while 1 isolate (0.94%) was resistant to RIF only. Notably, 31 isolates (29.24%) were resistant to both antibiotics. Of the 41 phenotypically INH-resistant isolates, 19 (46.3%) had the Ser315Thr mutation. There were 8 different rpoB mutations in 22 (68.8%) of the RIF-resistant isolates. The most frequently detected mutations were at codons 531 (37.5%), 526 (18.8%), and 516 (6.3%).

Conclusion: To help prevent new cases of DR-TB in Vietnam, it is crucial to gain a comprehensive understanding of the genotypic DR-TB isolates.

Keywords: Drug resistance; Genotypic characteristics in rpoB and katG; Real-time polymerase chain reaction TaqMan; Resazurin microtiter assay; Tuberculosis in central Vietnam.