Abstract
ABSTRACTBackgroundDirect whole genome sequencing (WGS) ofMycobacterium tuberculosis(Mtb) can be used as a tool to study drug resistance, mixed infections, and within host diversity. However, WGS is challenging from clinical samples due to low number of bacilli against a high background.MethodsWe prospectively collected 34 samples (sputum, n=17; bronchoalveolar lavage, BAL, n=13 and pus, n=4) from patients with active tuberculosis (TB). Prior to DNA extraction, we used a ligand-mediated magnetic bead method to enrichMtbfrom clinical samples and performed WGS on Illumina platform.ResultsMtbwas definitively identified based on WGS from 88.2% (30/34) of the samples of which 35.3% (12/34) were smear negative. The overall median genome coverage was 15.2% (IQR = 7.9-39.3). There was a positive correlation between load of bacilli on smears and genome coverage (p-value < 0.001). We detected 58 genes listed in the WHO mutation catalogue in each positive sample (median coverage = 85%, IQR = 61%-94%), enabling the identification of mutations missed by routine diagnostics. Mutations causing resistance to rifampicin, isoniazid, streptomycin, and ethambutol were detected in 5/34 (14.7%) samples, including therpoBS441A mutation that confers resistance to rifampicin which is not covered by Xpert MTB/RIF. This approach also allowed us to identify mixed infections in eight samples (BAL=4/8, pus=2/3 and sputum= 2/10) including samples that were infected with three or more different strains ofMtb.ConclusionsWe demonstrate the feasibility of magnetic bead-based enrichment for culture-free WGS ofMtbfrom clinical specimens, including smear-negative samples. This approach can also be integrated with low-cost sequencing workflows such as targeted sequencing for rapid detection ofMtband drug resistance.
Publisher
Cold Spring Harbor Laboratory
Reference45 articles.
1. World Health Organization. Global tuberculosis report 2023. World Health Organization, 2023. Available at: https://iris.who.int/bitstream/handle/10665/373828/9789240083851-eng.pdf?sequence=1. Accessed 09 November 2023
2. Central TB Division, Ministry of Health & Family Welfare, Government of India. India TB Report 2023. Cited 2023 May 15. Available from: https://tbcindia.gov.in/WriteReadData/l892s/5646719104TB%20AR-2023_23-%2003-2023_LRP.pdf. Accessed 24 August 2023
3. Clinical use of whole genome sequencing for Mycobacterium tuberculosis;BMC medicine,2016
4. Evolution and transmission of drug-resistant tuberculosis in a Russian population
5. Whole-genome sequencing for surveillance of fluoroquinolone resistance in rifampicin-susceptible tuberculosis in a rural district of Shanghai: A 10-year retrospective study