First proficiency testing of second-line anti-tuberculosis drug susceptibility testing in 12 provinces of China

Proficiency of phenotypic drug susceptibility testing for Mycobacterium tuberculosis in China, 2008-2021

To analyze the results of proficiency testing for anti-tuberculosis drug susceptibility testing (DST) in China. Number of laboratory participating the proficiency testing performed DST, and the sensitivity, specificity, reproducibility, and accordance rate were calculated from data of 13 rounds proficiency testing results for DST from 2008 to 2021. A total of 30 and 20 strains of Mycobacterium tuberculosis with known susceptibility results were sent to each laboratory in 2008 to 2019, 2020 and 2021, respectively. The number of participating laboratories ranged from 30 in 2009 to 546 in 2021. L-J DST was the predominant method. The specificity presented relatively higher than sensitivity. Improvement of specificity were observed for all drugs through the years, while sensitivity did not show improvement for amikacin and capreomycin. Accordance rate of pyrazinamide and kanamycin and reproducibility of capreomycin and pyrazinamide were not significantly improved through the years. Most of the participating laboratories significantly improved the quality of their DST through the consecutive rounds of proficiency testing except for second-line injectable drugs and pyrazinamide. The results highlight the importance of developing novel and/or improving existing methods for phenotypic DST for certain drugs.

Proficiency testing for drug susceptibility testing of Mycobacterium tuberculosis complex using commercial broth microdilution plate in China in 2021

OBJECTIVES

The characteristic and performance of Broth microdilution (BMD) plates for drug susceptibility of Mycobacterium tuberculosis have not been systematically evaluated in China. This study was designed to review the key information and assess the performance of BMD plates by analysis of proficiency testing results.

METHODS

We retrospectively analysed the proficiency testing results of phenotypic drug susceptibility testing (PT-DST) of 45 laboratories using BMD plates in China in 2021. Critical information, such as drug layout, concentration range of each drug, plate storage conditions and duration, operating procedures, and interpretation criteria for binary results were compared. The performance was also analysed.

RESULTS

Eight types of BMD plates produced by four manufactures were reported. The drug layout, number of drugs on plates, and concentration range varied a lot between different plates. The total sensitivity and specificity of BMD plates for drug susceptibility of Mycobacterium tuberculosis to ten drugs (isoniazid (INH), rifampin (RIF), kanamycin (KAM), amikacin (AM), levofloxacin (LFX), moxifloxacin (MFX), bedaquiline (BDQ), linezolid (LZD), clofazimine (CFZ), and delamanid (DLM)) were 93.9% (95% CI 92.-94.9) and 99.1% (95% CI 98.8-99.3), respectively. The lowest sensitivity was 84.8% (95% CI 80.3-88.4) for LFX and 86.4% (95% CI 82.5-89.6) for MFX, or 87.5% (95% CI 84.2-90.2) for Y1 plate and 87.9% (95% CI 83.5-91.1) for T plate. The lowest specificity was 94.4% (95% CI 91.4-96.4) for DLM, or 97.9% (95% CI 96.8-98.7) for B3 plate.

CONCLUSION

Commercial BMD plates in China showed varied drug layouts and operational procedures, indicating the urgency of standardization. The lower performance for some drugs showed the low quality of the plates utilized or lack of proficiency of lab staffs in operating and interpreting results.

Review of automated DNA extraction systems for sequencing-based solutions for drug-resistant tuberculosis detection

Robust clinical specimen nucleic acid extraction instrumentation and methods are critical to the performance of downstream molecular diagnostics for the diagnosis of drug-resistant tuberculosis (DR-TB). Currently, there is a high level of interest in sequencing-based solutions for rapid and comprehensive DR-TB testing from primary specimens (i.e., sputum). However, there is no standardized or fully automated sputum extraction system that has been widely implemented for use with Mycobacterium tuberculosis complex-containing sputum specimens. For sequencing-based technologies to be widely adopted in clinical laboratory settings in low- and middle-income countries, automated extraction technologies will be important to enhance scalability and reliability and to standardize performance of the downstream assays. Additionally, the ease of automatic technologies allows for faster uptake in laboratories currently without the expertise or infrastructure to perform manual extractions at the same automated throughput. This work is intended to provide an initial specification comparison of available automated DNA extraction systems that could serve as front-end components for existing and future sequencing approaches and provide the framework for future evaluations.

External quality control of phenotypic drug susceptibility testing for Mycobacterium tuberculosis in China

The aim of our study was to evaluate the performance of conventional drug susceptibility testing (DST) among the tuberculosis (TB)-specialized hospitals in China. A total of 40 hospitals participated in the external quality assurance program for assessment of DST results from each hospital. The sensitivity, specificity, and accuracy of DST were analyzed. The mean accuracy was 96.5% for isoniazid (INH), 95.8% for rifampin (RIF), 97.0% for ethambutol (EMB), 96.8% for ofloxacin (OFX), 97.1% for kanamycin (KAN), 96.1% for amikacin (AMK), and 93.6% for capreomycin (CAP), respectively. Of the 40 participating laboratories, 4 (10.0%) and 6 (15%) failed to achieve 90% accuracy for INH and RIF, respectively. In addition, six hospitals (15%) were confirmed as certified to provide reliable DST results for both first-line and second-line drugs. The certified proportion for DST dropped from 73.9% in the non-western region to 59.2% in the western region. The significant difference was observed in the certified proportion for first-line drugs between the western and non-western region (P = 0.013). Our results demonstrate that the quality of phenotypical DST is frequently unsatisfactory, with approximately one-third of participated laboratories failing to produce certified phenotypical DST results. In addition, the uncertified laboratories majorly come from the western region in China.

Evolution of Phenotypic and Molecular Drug Susceptibility Testing

Drug Resistant Tuberculosis (DRTB) is an emerging problem world-wide. In order to control the disease and decrease the number of cases overtime a prompt diagnosis followed by an appropriate treatment should be provided to patients. Phenotypic DST based on liquid automated culture has greatly reduced the time needed to generate reliable data but has the drawback to be expensive and prone to contamination in the absence of appropriate infrastructures. In the past 10 years molecular biology tools have been developed. Those tools target the main mutations responsible for DRTB and are now globally accessible in term of cost and infrastructures needed for the implementation. The dissemination of the Xpert MTB/rif has radically increased the capacity to perform the detection of rifampicin resistant TB cases. One of the main challenges for the large scale implementation of molecular based tests is the emergence of conflicting results between phenotypic and genotypic tests. This mines the confidence of clinicians in the molecular tests and delays the initiation of an appropriate treatment. A new technique is revolutionizing the genotypic approach to DST: the WGS by Next-Generation Sequencing technologies. This methodology promises to become the solution for a rapid access to universal DST, able indeed to overcome the limitations of the current phenotypic and genotypic assays. Today the use of the generated information is still challenging in decentralized facilities due to the lack of automation for sample processing and standardization in the analysis.The growing knowledge of the molecular mechanisms at the basis of drug resistance and the introduction of high-performing user-friendly tools at peripheral level should allow the very much needed accurate diagnosis of DRTB in the near future.

Integration of published information into a resistance-associated mutation database for Mycobacterium tuberculosis

Tuberculosis remains a major global public health challenge. Although incidence is decreasing, the proportion of drug-resistant cases is increasing. Technical and operational complexities prevent Mycobacterium tuberculosis drug susceptibility phenotyping in the vast majority of new and retreatment cases. The advent of molecular technologies provides an opportunity to obtain results rapidly as compared to phenotypic culture. However, correlations between genetic mutations and resistance to multiple drugs have not been systematically evaluated. Molecular testing of M. tuberculosis sampled from a typical patient continues to provide a partial picture of drug resistance. A database of phenotypic and genotypic testing results, especially where prospectively collected, could document statistically significant associations and may reveal new, predictive molecular patterns. We examine the feasibility of integrating existing molecular and phenotypic drug susceptibility data to identify associations observed across multiple studies and demonstrate potential for well-integrated M. tuberculosis mutation data to reveal actionable findings.