Accuracy of a reverse dot blot hybridization assay for simultaneous detection of the resistance of four anti-tuberculosis drugs in Mycobacterium tuberculosis isolated from China

Exploring gene mutations and multidrug resistance in Mycobacterium tuberculosis: a study from the Lung Hospital in Vietnam

BACKGROUND

Drug-resistant tuberculosis not only diminishes treatment efficacy but also heightens the risk of transmission and mortality. Investigating Mycobacterium tuberculosis resistance to first-line antituberculosis drugs is essential to tackle a major global health challenge.

METHODS AND RESULTS

Using Sanger sequencing, this study investigates gene mutations associated with multidrug resistance in drug-resistant M. tuberculosis strains. Among 30 samples, mutations were found in genes linked to first-line anti-tuberculosis drug resistance. Rifampicin resistance was observed in 46.67% of the samples, with the most frequent mutation in the rpoB gene at codon 450 (S450L) occurring in 23.33% of cases. Similarly, isoniazid resistance was found in 86.67% of samples, with 33.33% of cases indicating the katG gene mutation at codon 315 (S315T). Additionally, streptomycin resistance was present in 76.67% of samples, and 30% of these cases were mainly linked to the rpsL gene mutation at codon 43 (K43R).

CONCLUSION

These findings illuminate the genetic mechanisms behind drug resistance in M. tuberculosis. By identifying specific genetic markers, this research enhances our ability to diagnose and treat drug-resistant Tuberculosis more accurately and efficiently.

Drug Resistance Patterns and Trends in Patients with Suspected Drug-Resistant Tuberculosis in Dalian, China: A Retrospective Study

Purpose

The emergence of drug-resistant tuberculosis (DR-TB) represents a threat to the control of tuberculosis. This study aimed to estimate the patterns and trends of DR-TB in patients with suspected DR-TB. In addition, risk factors for multidrug-resistant tuberculosis (MDR-TB) were identified among suspected DR-TB patients in Dalian, China.

Patients and Methods

A total of 5661 patients with suspected DR-TB from Jan 1, 2013 to Dec 31, 2020 were included in the final analysis. The resistance pattern of all resistant strains was determined by drug susceptibility testing (DST) using the conventional Lowenstein-Jensen Proportion Method (LJ). DR-TB trends were estimated from 2013 to 2020. During the research period, the chi-square test was employed to analyze the significance of linear drug-resistance trends across time. Bivariate and multivariate logistic regression were performed to assess factors associated with MDR-TB.

Results

From 2013 to 2020, the resistance rates of rifampicin (RFP) and isoniazid (INH) decreased significantly, whereas the resistance rates of ethambutol (EMB) and streptomycin (SM) increased in patients with suspected DR-TB. From 2013 to 2020, the prevalence of DR-TB decreased in all patients from 34.71% to 28.01% with an average annual decrease of 3.02%. Among new cases, from 2013 to 2020, the prevalence of DR-TB (from 26.67% to 24.75%), RFP-resistant TB (RR-TB) (from 15.09% to 3.00%) and MDR-TB (from 6.08% to 2.62%) showed a significant downward trend. Among patients with a previous treatment history, DR-TB (from 54.70% to 37.50%), RR-TB (from 44.16% to 11.49%) and MDR-TB (from 26.90% to 10.34%) showed a significant downward trend from 2013 to 2020. Males (AOR 1.28, 95% CI 1.035–1.585), patients 45 to 64 years of age (AOR 1.75, 95% CI 1.342–2.284), patients 65 years and older (AOR 1.65, 95% CI 1.293–2.104), rural residents (AOR 1.24, 95% CI 1.014–1.519) and a previous treatment history (AOR 3.94, 95% CI 3.275–4.741) were risk factors for MDR-TB.

Conclusion

The prevalence of DR-TB, RR-TB and MDR-TB was significantly reduced from 2013 to 2020. Considerable progress has been made in the prevention and treatment of DR-TB during this period. However, the increasing rate of drug resistance in EMB and SM should be taken seriously. Suspected DR-TB patients who are male, older than 45 years of age, live in rural areas, and have a history of TB treatment should be given priority by health care providers.

Quantitative proteomics reveals that dormancy-related proteins mediate the attenuation in mycobacterium strains

Although members of the Mycobacterium tuberculosis complex (MTBC) exhibit high similarity, they are characterized by differences with respect to virulence, immune response, and transmissibility. To understand the virulence of these bacteria and identify potential novel therapeutic targets, we systemically investigated the total cell protein contents of virulent H37Rv, attenuated H37Ra, and avirulent M. bovis BCG vaccine strains at the log and stationary phases, based on tandem mass tag (TMT) quantitative proteomics. Data analysis revealed that we obtained deep-coverage protein identification and high quantification. Although 272 genetic variations were reported in H37Ra and H37Rv, they showed very little expression difference in log and stationary phase. Quantitative comparison revealed H37Ra and H37Rv had significantly dysregulation in log phase (227) compared with stationary phase (61). While BCG and H37Rv, and BCG and H37Ra showed notable differences in stationary phase (1171 and 1124) with respect to log phase (381 and 414). In the log phase, similar patterns of protein abundance were observed between H37Ra and BCG, whereas a more similar expression pattern was observed between H37Rv and H37Ra in the stationary phase. Bioinformatic analysis revealed that the upregulated proteins detected for H37Rv and H37Ra in log phase were virulence-related factors. In both log and stationary phases, the dysregulated proteins detected for BCG, which have also been identified as M. tuberculosis response proteins under dormancy conditions. We accordingly describe the proteomic profiles of H37Rv, H37Ra, and BCG, which we believe will potentially provide a better understanding of H37Rv pathogenesis, H37Ra attenuation, and BCG immuno protection.

Prevalence and Molecular Characteristics Based on Whole Genome Sequencing of Mycobacterium tuberculosis Resistant to Four Anti-Tuberculosis Drugs from Southern Xinjiang, China

Objective

Drug-resistant tuberculosis is a major public health problem, especially in the southern region of Xinjiang, China; however, there is little information regarding drug resistance profiles and mechanism of Mycobacterium tuberculosis in this area. The aim of this study was to determine the prevalence and molecular characteristics of M. tuberculosis resistant to four anti-tuberculosis drugs from this area.

Methods

Three hundred and forty-six isolates from the southern region of Xinjiang, China were included and used to perform phenotypic drug susceptibility testing and whole genome sequencing (WGS). Mutations in seven loci associated with drug resistance, including rpoB for rifampicin (RMP), katG, inhA promoter and oxyR-ahpC for isoniazid (INH), rrs 530 and 912 loops and rpsL for streptomycin (STR), and embB for ethambutol (EMB), were characterized.

Results

Among 346 isolates, 106, 60, 70 and 29 were resistant to INH, RMP, STR and EMB, respectively; 132 were resistant to at least one of the four anti-tuberculosis drugs and 51 were multi-drug resistant (MDR). Beijing genotype and retreated patients showed a significantly increased risk for developing MDR tuberculosis. Compared with the phenotypic data, the sensitivity and specificity for WGS to predict resistance were 96.7% and 98.6% for RMP, 75.5% and 97.1% for INH, 68.6% and 99.6% for STR, 93.1% and 93.7% for EMB, respectively. The most common mutations conferring RMP, INH, STR and EMB resistance were Ser450Leu (51.7%) in rpoB, Ser315Thr (44.3%) in katG, Lys43Arg (35.7%) in rpsL and Met306Val (24.1%) in embB.

Conclusion

This study provides the first information on the prevalence and molecular characters of drug resistant M. tuberculosis in the southern region of Xinjiang, China, which will be helpful for choosing early detection methods for drug resistance (ig, molecular methods) and subsequently initiation of proper therapy of tuberculosis in this area.

Detection of Resistance to Fluoroquinolones and Second-Line Injectable Drugs Among Mycobacterium tuberculosis by a Reverse Dot Blot Hybridization Assay

Background

Reliable and timely determination of second-line drug resistance is essential for early initiation effective anti-tubercular treatment among multi-drug resistant (MDR) patients and blocking the spread of MDR and extensively drug-resistant tuberculosis. Molecular methods have the potency to provide accurate and rapid drug susceptibility results. We aimed to establish and evaluate the accuracy of a reverse dot blot hybridization (RDBH) assay to simultaneously detect the resistance of fluoroquinolones (FQs), kanamycin (KN), amikacin (AMK), capreomycin (CPM) and second-line injectable drugs (SLIDs) in Mycobacterium tuberculosis.

Methods

We established and evaluated the accuracy of the RDBH assay by comparing to the phenotypic drug susceptibility testing (DST) and sequencing in 170 M. tuberculosis, of which 94 and 27 were respectively resistant to ofloxacin (OFX) and SLIDs.

Results

The results show that, compared to phenotypic DST, the sensitivity and specificity of the RDBH assay for resistance detection were 63.8% and 100.0% for OFX, 60.0% and 100.0% for KN, 61.5% and 98.1% for AMK, 50.0% and 99.3% for CPM, and 55.6% and 100% for SLIDs, respectively; compared to sequencing, the sensitivity and specificity of the RDBH assay were 95.2% and 100.0% for OFX, 93.8% and 100.0% for SLIDs or KN (both based on mutations in rrs 1400 region and eis promoter), and 91.6% and 100.0% for AMK or CPM (both based on mutations in rrs 1400 region), respectively. The turnaround time of the RDBH assay was 7 h for testing 42 samples.

Conclusion

Our data suggested that compared to sequencing, the RDBH assay could serve as a rapid and reliable method for testing the resistance of M. tuberculosis against OFX and SLIDs, enabling early administration of appropriate treatment regimens among MDR tuberculosis patients.

Genomic Analysis Identifies Mutations Concerning Drug-Resistance and Beijing Genotype in Multidrug-Resistant Mycobacterium tuberculosis Isolated From China

Development of modern genomics provides us an effective method to understand the molecular mechanism of drug resistance and diagnose drug-resistant Mycobacterium tuberculosis. In this study, mutations in 18 genes or intergenic regions acquired by whole-genome sequencing (WGS) of 183 clinical M. tuberculosis strains, including 137 multidrug-resistant and 46 pan-susceptible isolates from China, were identified and used to analyze their associations with resistance of isoniazid, rifampin, ethambutol, and streptomycin. Using the proportional method as the gold standard method, the accuracy values of WGS to predict resistance were calculated. The association between synonymous or lineage definition mutations with different genotypes were also analyzed. The results show that, compared to the phenotypic proportional method, the sensitivity and specificity of WGS for resistance detection were 94.2 and 100.0% for rifampicin (based on mutations in rpoB), 90.5 and 97.8% for isoniazid (katG), 83.0 and 97.8% for streptomycin (rpsL combined with rrs 530 loop and 912 loop), and 90.9 and 65.1% for ethambutol (embB), respectively. WGS data also showed that mutations in the inhA promoter increased only 2.2% sensitivity for INH based on mutations in katG. Synonymous mutation rpoB A1075A was confirmed to be associated with the Beijing genotype. This study confirmed that mutations in rpoB, katG, rrs 530 loop and 912 loop, and rpsL were excellent biomarkers for predicting rifampicin, isoniazid, and streptomycin resistance, respectively, and provided clues in clarifying the drug-resistance mechanism of M. tuberculosis isolates from China.