Universal Drug Susceptibility Testing Research Articles

Quantitative measurement of antibiotic resistance in Mycobacterium tuberculosis reveals genetic determinants of resistance and susceptibility in a target gene approach

The World Health Organization has a goal of universal drug susceptibility testing for patients with tuberculosis. However, molecular diagnostics to date have focused largely on first-line drugs and predicting susceptibilities in a binary manner (classifying strains as either susceptible or resistant). Here, we used a multivariable linear mixed model alongside whole genome sequencing and a quantitative microtiter plate assay to relate genomic mutations to minimum inhibitory concentration (MIC) in 15,211 Mycobacterium tuberculosis clinical isolates from 23 countries across five continents. We identified 492 unique MIC-elevating variants across 13 drugs, as well as 91 mutations likely linked to hypersensitivity. Our results advance genetics-based diagnostics for tuberculosis and serve as a curated training/testing dataset for development of drug resistance prediction algorithms.

Universal drug-susceptibility testing of first-line drugs to preserve their efficacy: An essential strategy to defeat tuberculosis

Universal drug-susceptibility testing of first-line drugs to preserve their efficacy: An essential strategy to defeat tuberculosis

Treatment outcome of drug-resistant tuberculosis (DR-TB) following uptake of universal drug susceptibility testing: A record review from a nodal DR-TB center

Background: There has been delay evident in diagnosing the drug resistance and non-initiation of appropriate treatment based on drug susceptibility pattern resulting in poor treatment outcome of drug-resistant tuberculosis (DR-TB). Aims and Objectives: The aims of this study were to examine the treatment outcomes for DR-TB patients following universal drug susceptibility testing (UDST) and to examine the association of sociodemographic, behavioral factors, or comorbidities with outcome. Materials and Methods: A retrospective study at a nodal DR-TB center was done for the past 2 years (2018–2019) following the district’s adoption of UDST. The study comprised patients registered between January 2018 and December 2019. Transferred out cases were excluded from the analysis. Cured or treatment completed were assigned as successful, whereas the treatment failed, lost to follow-up or died were adverse treatment outcome. Results: A total of 201 patients were initiated on suitable DOTS regime and they continued the treatment from the center, during the study period. Altogether 129 (64.2%) patients had successful treatment outcome. None of the examined variable (age, sex, SES, Body mass index, and comorbidity) is found to have statistically significant association with outcome (P>0.05). Conclusion: The UDST may be the reason for success rate shown here, higher than in literature published. Although a better stance is possible only by comparing the treatment outcome of pre- and post-uptake of UDST from same setting.

Clinical Evaluation of the XDR-LFC Assay for the Molecular Detection of Isoniazid, Rifampin, Fluoroquinolone, Kanamycin, Capreomycin, and Amikacin Drug Resistance in a Prospective Cohort.

While the goal of universal drug susceptibility testing has been a key component of the WHO End TB Strategy, in practice, this remains inaccessible to many. Rapid molecular tests for tuberculosis (TB) and antituberculosis drug resistance could significantly improve access to testing. In this study, we evaluated the accuracy of the Akonni Biosystems XDR-TB (extensively drug-resistant TB) TruArray and lateral-flow-cell (XDR-LFC) assay (Akonni Biosystems, Inc., Frederick, MD, USA), a novel assay that detects mutations in seven genes associated with resistance to antituberculosis drugs: katG, the inhA promoter, and the ahpC promoter for isoniazid; rpoB for rifampin; gyrA for fluoroquinolones; rrs and the eis promoter for kanamycin; and rrs for capreomycin and amikacin. We evaluated assay performance using direct sputum samples from 566 participants recruited in a prospective cohort in Moldova over 2 years. The sensitivity and specificity against the phenotypic reference were both 100% for isoniazid, 99.2% and 97.9% for rifampin, 84.8% and 99.1% for fluoroquinolones, 87.0% and 84.1% for kanamycin, 54.3% and 100% for capreomycin, and 79.2% and 100% for amikacin, respectively. Whole-genome sequencing data for a subsample of 272 isolates showed 95 to 99% concordance with the XDR-LFC-reported suspected mutations. The XDR-LFC assay demonstrated a high level of accuracy for multiple drugs and met the WHO's minimum target product profile criteria for isoniazid and rifampin, while the sensitivity for fluoroquinolones and amikacin fell below target thresholds, likely due to the absence of a gyrB target in the assay. With optimization, the XDR-LFC shows promise as a novel near-patient technology to rapidly diagnose drug-resistant tuberculosis.

Status of Universal Drug Susceptibility Testing in Pulmonary Tuberculosis Patients Initiated on Treatment in an Urban Setting, South India.

Early initiation of drug susceptibility testing (DST) guided anti-tuberculosis treatment benefits the patient in terms of better treatment outcomes and possibly reduces the transmission of tuberculosis (TB) disease in the community. To determine the status of universal DST (UDST) coverage in smear-positive pulmonary TB patients (PTB) initiated on treatment under the TB program in Greater Chennai Corporation. In addition, the barriers and facilitators for UDST were explored. The data of PTB patients who were initiated on anti-TB treatment from July to December 2019 was abstracted from the NI-KSHAY database of TB Program. The barriers and facilitators for UDST were explored in 5 focus group discussions (FGDs) among the TB program healthcare workers (HCW). UDST coverage was based on the availability of Cartridge-based Nucleic Acid Amplification test (CBNAAT) results in the NI-KSHAY database. The CBNAAT result was available for 1628 (82.6%) of the 1970 smear-positive PTB patients. Non-availability of CBNAAT results was significantly higher among the older age group (>50 years), in female PTB patients, and the Private Sector. Issues with sputum collection, transport of specimens, and receipt of results were highlighted by the HCWs for the non-availability of UDST results. Universal DST coverage in smear-positive PTB patients initiated on treatment in 2019 in Chennai was optimal as per National Strategic Plan for TB elimination UDST target of 80% for the year 2020 but with scope for improvement. The low UDST coverage in the private sector, among female patients and older age groups, needs to be addressed.

Status of universal drug-susceptibility testing among sputum smear-positive tuberculosis patients diagnosed at a tertiary care centre.

This study was aimed at estimating the proportion among sputum smear-positive tuberculosis (TB) patients diagnosed at a tertiary care centre in India, who did not undergo universal drug-susceptibility testing (UDST), assessing the sociodemographic and morbidity-related factors associated with it, ascertaining the reasons for not getting tested and estimating the proportion with any drug resistance (DR). TB Notification Register and TB Laboratory Register, maintained in Designated Microscopy Centre and Intermediate Research Laboratory, respectively were used to obtain the patient details and information regarding UDST and DR-TB status. Under UDST, the TB patients had undergone rapid molecular tests to check for any DR. TB patients who dropped out of this strategy (those who did not submit a sputum sample for DR testing even after being instructed) were telephonically contacted and asked regarding reasons for not getting themselves tested. Of the 215 patients, 74 [34.4%, 95% confidence interval (CI): 28.1-41.2] did not undergo UDST. Of these 74 participants, 60 per cent reported the reason that they were not informed regarding the drug-susceptibility test. Among the 141 patients who underwent UDST, six (4.3%, 95% CI: 1.58-9.03) had DR. Non-UDST patients were significantly more in percentage among TB patients who were aged <30 years (adjusted prevalence ratio 2.36; 95% CI: 1.19-4.68) compared to >60 years. The present findings point towards a need to sensitize healthcare workers and TB patients to improve UDST.

Implementing molecular tuberculosis diagnostic methods in limited-resource and high-burden countries.

Tuberculosis (TB) is one of the deadliest infectious diseases in the world with more than a million people dying of TB each year. Accurate and timely TB diagnosis has the potential to alleviate the global TB burden; therefore, one of the pillars of the End TB Strategy developed by the World Health Organization (WHO) is the early diagnosis of TB, including universal drug-susceptibility testing (DST). The WHO emphasises the importance of DST before treatment initiation, using molecular WHO-recommended rapid diagnostic tests (mWRDs). Currently available mWRDs are nucleic acid amplification tests, line probe assays, whole genome sequencing, and targeted next-generation sequencing. However, implementing the sequencing mWRDs in routine laboratories in low-income countries is constrained by the existing infrastructure, high cost, the specialised skills needed, data storage, and the current delay in results compared with other routine methods. These limitations are pronounced in resource-limited settings, which often have a high TB burden and need for innovative TB diagnostic technologies. In this article we propose several possible solutions, like adapting infrastructure capacity to needs, advocating for lowering costs, building bioinformatics and laboratory capacity, and increasing the use of open-access resources for software and publications.

Drug resistance patterns and dynamics of tuberculosis in Zhejiang Province, China: Results from five periodic longitudinal surveys.

As one of the high multi-drug resistance tuberculosis countries, it is critical for China to understand patterns of drug resistance to better formulate effective treatment regimens. The anti-TB Drug resistance surveillance has been conducted in Zheijang Province in years 1999, 2004, 2008, 2013, and 2018 respectively. We compared the prevalence of DR-TB from the latest survey with that of the previous four surveys in terms of all four first-line anti-TB drugs. We also examined the prevalence of rifampin-resistant TB (RR-TB) between the last two surveys and routine surveillance data. Among 996 patients surveyed in 2018, the prevalence of RR-TB in new and previously treated TB cases was 2.5 and 4.3%, respectively. The prevalence of RR-TB among previously treated cases was much higher than for new cases in the four surveys from 1999 to 2013, while there was no significant difference between these groups in the 2018 survey. The percentage of TB cases resistant to fluoroquinolones in new patients was 3.8%. The prevalence of non-tuberculous mycobacteria increased over time; the prevalence of RR-TB among new cases slowly decreased. The prevalence of RR-TB in both new and previously treated TB cases from the latest two surveys was consistent with routine surveillance data. This consistency between routine surveillance and periodic surveys for TB cases implies that with universal testing in Zhejiang Province, data from routine surveillance could be used instead of periodic surveys to improve access to timely and appropriate treatment for DR-TB. Levels of resistance were lower than whole-country and global estimates, further indicating the value of universal drug susceptibility testing.

In silico evaluation of WHO-endorsed molecular methods to detect drug resistant tuberculosis

Universal drug susceptibility testing (DST) for tuberculosis is a major goal of the END TB strategy. PCR-based molecular diagnostic tests have been instrumental in increasing DST globally and several assays have now been endorsed by the World Health Organization (WHO) for use in the diagnosis of drug resistance. These endorsed assays, however, each interrogate a limited number of mutations associated with resistance, potentially limiting their sensitivity compared to sequencing-based methods. We applied an in silico method to compare the sensitivity and specificity of WHO-endorsed molecular based diagnostics to the mutation set identified by the WHO mutations catalogue using phenotypic DST as the reference. We found that, in silico, the mutation sets used by probe-based molecular diagnostic tests to identify rifampicin, isoniazid, pyrazinamide, levofloxacin, moxifloxacin, amikacin, capreomycin and kanamycin resistance produced similar sensitivities and specificities to the WHO mutation catalogue. PCR-based diagnostic tests were most sensitive for drugs where mechanisms of resistance are well established and localised to small genetic regions or a few prevalent mutations. Approaches using sequencing technologies can provide advantages for drugs where our knowledge of resistance is limited, or where complex resistance signatures exist.

The second national anti-tuberculosis drug resistance survey in Tanzania, 2017-2018.

To determine the levels and patterns of resistance to first- and second-line anti-tuberculosis (TB) drugs among new and previously treated sputum smear positive pulmonary TB (PTB) patients. We conducted a nationally representative cross-sectional facility-based survey in June 2017-July 2018 involving 45 clusters selected based on probability proportional to size. The survey aimed to determine the prevalence of anti-TB drug resistance and associated risk factors among smear positive PTB patients in Tanzania. Sputum samples were examined using smear microscopy, Xpert MTB/RIF, culture and drug susceptibility testing (DST). Logistic regression was used to account for missing data and sampling design effects on the estimates and their standard errors. We enrolled 1557 TB patients, including 1408 (90.4%) newly diagnosed and 149 (9.6%) previously treated patients. The prevalence of multidrug-resistant TB (MDR-TB) was 0.85% [95% confidence interval (CI): 0.4-1.3] among new cases and 4.6% (95% CI: 1.1-8.2) among previously treated cases. The prevalence of Mycobacterium tuberculosis strains resistant to any of the four first-line anti-TB drugs (isoniazid, rifampicin, streptomycin and ethambutol) was 1.7% among new TB patients and 6.5% among those previously treated. Drug resistance to all first-line drugs was similar (0.1%) in new and previously treated patients. None of the isolates displayed poly-resistance or extensively drug-resistant TB (XDR-TB). The only risk factor for MDR-TB was history of previous TB treatment (odds ratio=5.7, 95% CI: 1.9-17.2). The burden of MDR-TB in the country was relatively low with no evidence of XDR-TB. Given the overall small number of MDR-TB cases in this survey, it will be beneficial focusing efforts on intensified case detection including universal DST.

Experience on the first national anti-TB drug resistance survey (DRS) in Timor-Leste

BackgroundA national drug resistance survey (DRS) was implemented for the first time in Timor-Leste (TL) in 2019. The primary objective of the survey was to assess the prevalence of drug resistance among new and previously treated pulmonary TB patients in the country.MethodsThis nation-wide cross-sectional survey was conducted in 2019 targeting all new and previously treated sputum smear-positive pulmonary TB patients. Sputum samples were submitted to the National TB Reference Laboratory for confirmation of TB and to determine resistance to rifampicin by Xpert MTB/RIF. Culture was performed on solid media, and culture isolates of confirmed TB cases were shipped to the WHO Supranational TB Reference Laboratory in Chennai, India for whole genome sequencing (WGS). Survey summary statistics, data cross-tabulations and analysis of potential risk factors of rifampicin-resistant TB (RR-TB) were conducted using R statistical software (version 3.5.2).ResultsA total of 953 sputum-smear positive patients were enrolled, of which 917 were confirmed as positive for TB by either Xpert MTB/RIF or culture. An electronic web-based system was used for entry and storage of the data. Rifampicin resistance was detected among 0.6% (95% CI 0.2–1.3) of new cases and 2.7% (95% CI 0.5- 8.2) of previously treated cases. WGS was conducted for validation purposes on 65 randomly selected isolates (29% of RR-TB (2/7) and 7% of RS-TB (63/910) by Xpert MTB/RIF or pDST). The original test results agreed with the WGS validation results for 62/64 isolates (97%).ConclusionThe prevalence of RR-TB in Timor-Leste is relatively low compared to the estimated proportions of RR-TB in the WHO South-East Asia Region (2.5% [95% CI 1.9–3.3] among new cases and 14% [95% CI 7.7–21] among previously treated cases). The rapid sputum collection and transportation mechanism implemented in the survey demonstrates its feasibility in low resource settings and should be replicated for routinely transporting TB specimens from microscopy labs to GeneXpert sites. Establishment of in-country capacity for rapid molecular diagnostics for both first- and second-line DST is an immediate need for achieving universal drug susceptibility testing (DST) to guide appropriate patient management.

Trends in rifampicin and isoniazid resistance in patients with presumptive TB.

BACKGROUND: Early diagnosis of drug-resistant TB (DR-TB) is crucial in preventing the spread of the disease in the community. Introduction of upfront decentralised drug susceptibility testing to district-level as part of universal drug susceptibility testing (UDST) policy increased the feasibility of rapid and early testing for drug resistance closer to the patient and has resulted in reduced circumstances for transmission. The introduction of the first-line line-probe assay (FL-LPA), GenoType® MTBDRplus v2, has had an extensive impact on the management of multidrug-resistant TB (MDR-TB) in India.MATERIALS and METHODS: Sputum samples of patients with presumptive TB and DR-TB from selected districts of Tamil Nadu received through National TB Elimination Programme (NTEP) were subjected to FL-LPA as per programme guidelines. In this study, we present trends in genotypic resistance to isoniazid (INH) and rifampicin (RIF) during the 4 years (2016-2019) among these patients. Band patterns were analysed as per the updated GLI (Global Laboratory Initiative) LPA interpretation and reporting guidelines.RESULTS: A total of 26,349 samples were received during the study period. Smear-positive samples (n = 20231) were directly subjected to FL-LPA; smear-negative samples were cultured in liquid media and M. tuberculosis-positive cultures were tested using FL-LPA. A total of 18,441 were MTB-positive on FL-LPA. INH monoresistance, RIF monoresistance and MDR-TB was observed in respectively 8.7%, 1.1% and 3.3% of the samples. There was a decreasing trend in all types of resistance observed particularly after 2017 (P < 0.001). MDR-TB showed a steady decrease from 5.6% to 1.8%. S531L (19.5%) and S315T (61.1%) were the most common mutations identified in the rpoB and katG genes, respectively. The percentage of inhA-c-15t promoter mutation, indicating low-level INH resistance, showed a consistent increase (P < 0.001).CONCLUSION: The impact of the UDST policy on the NTEP may have led to this decreasing trend in RIF and INH resistance observed in the study period. The increase in low-level INH resistance mutation inhA-c-15t may be associated with ethionamide/prothionamide resistance, and this should be taken into account when designing DR-TB regimen.

The 2021 WHO catalogue of Mycobacterium tuberculosis complex mutations associated with drug resistance: a genotypic analysis

BackgroundMolecular diagnostics are considered the most promising route to achieving rapid, universal drug susceptibility testing for Mycobacterium tuberculosiscomplex (MTBC). We aimed to generate a WHO endorsed catalogue of mutations to serve as a global standard for interpreting molecular information for drug resistance prediction.MethodsA candidate gene approach was used to identify mutations as associated with resistance, or consistent with susceptibility, for 13 WHO endorsed anti-tuberculosis drugs. 38,215 MTBC isolates with paired whole-genome sequencing and phenotypic drug susceptibility testing data were amassed from 45 countries. For each mutation, a contingency table of binary phenotypes and presence or absence of the mutation computed positive predictive value, and Fisher’s exact tests generated odds ratios and Benjamini-Hochberg corrected p-values. Mutations were graded as Associated with Resistance if present in at least 5 isolates, if the odds ratio was >1 with a statistically significant corrected p-value, and if the lower bound of the 95% confidence interval on the positive predictive value for phenotypic resistance was >25%. A series of expert rules were applied for final confidence grading of each mutation.Findings15,667 associations were computed for 13,211 unique mutations linked to one or more drugs. 1,149/15,667 (7·3%) mutations were classified as associated with phenotypic resistance and 107/15,667 (0·7%) were deemed consistent with susceptibility. For rifampicin, isoniazid, ethambutol, fluoroquinolones, and streptomycin, the mutations’ pooled sensitivity was >80%. Specificity was over 95% for all drugs except ethionamide (91·4%), moxifloxacin (91·6%) and ethambutol (93·3%). Only two resistance mutations were classified for bedaquiline, delamanid, clofazimine, and linezolid as prevalence of phenotypic resistance was low for these drugs.InterpretationThis first WHO endorsed catalogue of molecular targets for MTBC drug susceptibility testing provides a global standard for resistance interpretation. Its existence should encourage the implementation of molecular diagnostics by National Tuberculosis Programmes.FundingUNITAID, Wellcome, MRC, BMGF.

Impact of Treatment Supporters on the Treatment Outcomes of Drug Resistant-Tuberculosis (DR-TB) Patients: A Retrospective Cohort Study.

Background: Drug resistant-tuberculosis (DR-TB) patients are provided universal drug susceptibility testing (UDST), anti-TB drugs for the treatment of DR-TB, nutritional support (Nikshay Poshan Yojana - the financial incentive of rupees five hundred per month for each notified DR-TB patient for the duration for which the patient is on anti-TB drugs) by the Government of India.Methods: This retrospective cohort record-based study was conducted in DR-TB patients. Some 1095 DR-TB patients who have initiated treatment at Nodal DR-TB Centre, Darbhanga Medical College and Hospital (DMCH), Darbhanga, and continued their anti-TB drugs at home blocks were followed till their treatment outcome was known. Data were analyzed by statistical experts of DMCH.Results: Treatment supporters comprised 688 (62.83%) females and 407 (37.17%) males. Different types of treatment supporters noted were accredited social health activists (ASHAs) 622 (56.80%), family members 365 (33.33%), and community health workers 108 (09.86%). Treatment outcome as transfer out was observed in 08 (1.29%), 10 (2.74%), and 13 (12.03%) cases among ASHAs, family members, and community health workers, respectively [statistically significant (p < 0.0001)].Conclusion: ASHAs proved to be the best treatment supporters in comparison to both family members and community health workers for multi-drug resistant TB (MDR/RR-TB) patients.

Direct Molecular Detection of Drug-Resistant Tuberculosis from Transported Bio-Safe Dried Sputum on Filter-Paper.

In 2019, amongst half a million new rifampicin-resistant tuberculosis (TB) cases, 78% were multi drug-resistant TB (MDR-TB). Access to rapid and Universal-Drug susceptibility testing (DST) to patients in remote areas is a major challenge to combat drug-resistant TB. To overcome this challenge, we had recently reported the development of 'TB Concentration & Transport kit' for bio-safe ambient temperature transport of dried sputum on filter-paper (Trans-Filter). The present study was conducted to evaluate the utility of DNA extracted from sputum on Trans-Filter in a Multiplex PCR-based sequencing assay (Mol-DSTseq) for diagnosing drug-resistant TB. The developed Mol-DSTseq assays were standardized on Mycobacterium tuberculosis clinical isolates (n = 98) and further validated on DNA extracted from sputum on Trans-Filter (n = 100). Using phenotypic DST as gold standard, the Mol-DSTseq assay showed 100% (95% Confidence Interval [CI] 79.4-100%) and 73.3% (95% CI 54.1-87.7%) sensitivity for detecting rifampicin and isoniazid resistance with a specificity of 85.1% (95% CI 66.2-95.8%) and 100% (95% CI:82.3-100%), respectively. For fluoroquinolones and aminoglycosides, the Mol-DSTseq assay showed a sensitivity of 78.5% (95% CI 49.2-95.3%) and 66.6% (95% CI 9.4-99.1%) with a specificity of 88.2% (95% CI 72.5-96.7%) and 100% (95% CI 93.1-100%), respectively. The Mol-DSTseq assays exhibited a high concordance of ~ 83-96% (κ value: 0.65-0.81) with phenotypic DST for all drugs. In conclusion, the 'TB Concentration and Transport kit' was compatible with Mol-DSTseq assays and has the potential to provide 'Universal-DST' to patients residing in distant areas in high burden countries, like India for early initiation of anti-tubercular treatment.

Early mortality during rifampicin-resistant TB treatment.

SUMMARYBACK GROUND:Data suggest that treatment with newer TB drugs (linezolid [LZD], bedaquiline [BDQ] and delamanid [DLM]), used in Khayelitsha, South Africa, since 2012, reduces mortality due to rifampicin-resistant TB (RR-TB).METHODS:This was a retrospective cohort study to assess 6-month mortality among RR-TB patients diagnosed between 2008 and 2019.RESULTS:By 6 months, 236/2,008 (12%) patients died; 12% (78/651) among those diagnosed in 2008–2011, and respectively 8% (49/619) and 15% (109/738) with and without LZD/BDQ/DLM in 2012–2019. Multivariable analysis showed a small, non-significant mortality reduction with LZD/BDQ/DLM use compared to the 2008–2011 period (aOR 0.79, 95% CI 0.5–1.2). Inpatient treatment initiation (aOR 3.2, 95% CI 2.4–4.4), fluoroquinolone (FQ) resistance (aOR 2.7, 95% CI 1.8–4.2) and female sex (aOR 1.5, 95% CI 1.1–2.0) were also associated with mortality. When restricted to 2012–2019, use of LZD/BDQ/DLM was associated with lower mortality (aOR 0.58, 95% CI 0.39–0.87).CONCLUSIONS:While LZD/BDQ/DLM reduced 6-month mortality between 2012 and 2019, there was no significant effect overall. These findings may be due to initially restricted LZD/BDQ/DLM use for those with high-level resistance or treatment failure. Additional contributors include increased treatment initiation among individuals who would have otherwise died before treatment due to universal drug susceptibility testing from 2012, an effect that also likely contributed to higher mortality among females (survival through to care-seeking).

Transmission patterns of rifampicin resistant Mycobacterium tuberculosis complex strains in Cameroon: a genomic epidemiological study

BackgroundDetermining factors affecting the transmission of rifampicin (RR) and multidrug-resistant (MDR) Mycobacterium tuberculosis complex strains under standardized tuberculosis (TB) treatment is key to control TB and prevent the evolution of drug resistance.MethodsWe combined bacterial whole genome sequencing (WGS) and epidemiological investigations for 37% (n = 195) of all RR/MDR-TB patients in Cameroon (2012–2015) to identify factors associated with recent transmission.ResultsPatients infected with a strain resistant to high-dose isoniazid, and ethambutol had 7.4 (95% CI 2.6–21.4), and 2.4 (95% CI 1.2–4.8) times increased odds of being in a WGS-cluster, a surrogate for recent transmission. Furthermore, age between 30 and 50 was positively correlated with recent transmission (adjusted OR 3.8, 95% CI 1.3–11.4). We found high drug-resistance proportions against three drugs used in the short standardized MDR-TB regimen in Cameroon, i.e. high-dose isoniazid (77.4%), ethambutol (56.9%), and pyrazinamide (43.1%). Virtually all strains were susceptible to fluoroquinolones, kanamycin, and clofazimine, and treatment outcomes were mostly favourable (87.5%).ConclusionPre-existing resistance to high-dose isoniazid, and ethambutol is associated with recent transmission of RR/MDR strains in our study. A possible contributing factor for this observation is the absence of universal drug susceptibility testing in Cameroon, likely resulting in prolonged exposure of new RR/MDR-TB patients to sub-optimal or failing first-line drug regimens.

Extrapulmonary tuberculosis

Introduction: Tuberculosis (TB) is a major cause of morbidity and mortality globally. Extrapulmonary TB (EPTB) constitutes about 15%-20% of all TB patients but accounts for 50% among HIV-coinfected. Confirmation of microbial diagnosis of EPTB is usually challenging. Areas covered: Availability of newer imaging modalities like 18FDG-PET-CT, PET-MRI, has facilitated precise anatomical localization of the lesions and mapping the extent of EPTB. The use of image-, endoscopy-guided invasive diagnostic methods has made procurement of tissue/body fluids for diagnostic testing possible. With the advent of universal drug-susceptibility testing, a rapid diagnosis of drug-resistance is now possible in EPTB. Drug-susceptible EPTB usually responds well to first-line anti-TB treatment; TB meningitis, bone and joint TB and lymph node TB often require longer duration of treatment. Expert opinion: Adjunctive use of corticosteroids in the initial period is recommended in central nervous system and pericardial TB. Surgical intervention is helpful to obtain tissue samples for diagnosis. Adjunctive surgical treatment along with medical treatment is useful in treating complications like hydrocephalus, Pott’s spine. Follow-up of EPTB patients is crucial as treatment is usually longer, requires recognition of development of immune reconstitution and inflammatory syndrome (IRIS), monitoring of adverse events, serious adverse events like anti-TB drug-induced hepatotoxicity, organ-related complications and treatment adherence.

Journey of Tuberculosis Control in India: From then till now

The history of Tuberculosis control in India dates back to 1951 with mass vaccination with BCG and it started as a National Programme in 1962. Radical changes in the form of DOTS were incorporated with the start of Revised National Tuberculosis Control Programme (RNTCP) in 1997. Since then, TB control efforts have witnessed many changes in the form of daily DOTS, Injection free regimen for both drug sensitive &amp; drug resistant TB, moving from fixed Categories of treatment regimen to Individualized treatment regimen based on prior Universal Drug susceptibility testing. Flexibility has been incorporated in the programme to accommodate Private practitioners in the form of various incentives. Introduction of Active case finding strategy has helped in early diagnosis leading to prompt treatments. Engagement of Community and leaders from all sectors and various organizations has helped to reach all communities in this fight against TB. India hopes to End TB by 2025 with rechristening the programme to National TB Elimination Programme (NTEP) and bringing in the much needed changes &amp; flexibilities in the programme.

Compatibility of a novel filter paper-based bio-safe sputum transport kit with line probe assay for diagnosing drug-resistant tuberculosis: a single-site evaluation study.

BackgroundNear-patient access to appropriate tests is a major obstacle for the efficient diagnosis of tuberculosis (TB) and associated drug resistance.MethodsWe recently developed the “TB Concentration & Transport” kit for bio-safe, ambient-temperature transportation of dried sputum on Trans-Filter, and the “TB DNA Extraction” kit for DNA extraction from Trans-Filter for determining drug resistance by DNA sequencing. In the present study, we evaluated the compatibility of Kit-extracted DNA with Hain's line probe assays (LPAs), which are endorsed by National TB programmes for the detection of drug resistance in sputum collected from presumptive multidrug-resistant TB patients (n=207).ResultsTrans-Filter-extracted DNA was seamlessly integrated with the LPA protocol (Kit-LPA). The sensitivity of Kit-LPA for determining drug resistance was 83.3% for rifampicin (95% CI 52–98%), 77.7% for isoniazid (95% CI 52–94%), 85.7% for fluoroquinolones (95% CI 42–100%) and 66.6% for aminoglycosides (95% CI 9–99%), with a specificity range of 93.7% (95% CI 87–97) to 99.1% (95% CI 95–100) using phenotypic drug susceptibility testing (DST) as a reference standard. A high degree of concordance was noted between results obtained from Kit-LPA and LPA (99% to 100% (κ value: 0.83–1.0)).ConclusionsThis study demonstrates successful integration of our developed kits with LPA. The adoption of these kits across Designated Microscopy Centres in India can potentially overcome the existing challenge of transporting infectious sputum at controlled temperature to centralised testing laboratories and can provide rapid near-patient cost-effective “Universal DST” services to TB subjects residing in remote areas.