Drug resistance patterns among extra-pulmonary tuberculosis cases in a tertiary care centre in North India

Epidemiology and effects of sociodemographic factors on extrapulmonary tuberculosis in Ambala, India

BACKGROUND

An ambitious plan was set into motion with the aim of TB elimination from India in 2025. To achieve this, it is high time to give emphasis on other prevalent forms of TB, such as extra pulmonary TB (EPTB).

OBJECTIVES

The study aims to discern the differences in patient characteristics and management practices between pulmonary TB and EPTB using data from district Ambala.

METHODS

This retrospective study used data of 12,985 TB patients from district Ambala, India. The differences in patient characteristics and management practices between pulmonary TB and EPTB were analyzed using the NIKSHAY database.

RESULTS

In the studied population, extra pulmonary TB (EPTB) formed 29.7% of all TB cases. Among all EPTB cases, pleural TB was found to be the most common form, accounting for 27%. The study also revealed that female gender, young age, non-diabetic status, and high BMI were associated with an increased propensity to have EPTB. Interestingly, unlike pulmonary TB, which had increased odds for contracting the disease in diabetic individuals (OR - 2.02), there were no increased odds for contracting EPTB in diabetic individuals. However, HIV infection significantly increased the odds for both pulmonary TB and EPTB. The results also showed diagnostic discrepancies between the private and public sectors, along with a low microbiological confirmation rate of 7.1% in EPTB cases.

CONCLUSION

The study highlights the importance of focusing on EPTB in addition to pulmonary TB for effective TB elimination in India. The differences in patient characteristics and management practices warrant further investigation and targeted interventions for both forms of the disease. Efforts should be made to improve diagnostic accuracy and reduce discrepancies between the private and public sectors.

Isoniazid resistance in Rifampicin sensitive pulmonary tuberculosis in children and adolescents

BACKGROUND

Isoniazid (INH) and Rifampicin (RIF) are two crucial drugs used in antitubercular therapy. INH is known for its potent bactericidal effects and has a relatively higher prevalence of resistance compared to RIF. However, RIF resistance has been the subject of more extensive research. On the other hand, Ethambutol (EMB) and Streptomycin (STR) resistance have not been thoroughly studied, particularly in the context of children and adolescents. To address this knowledge gap, a study was designed to investigate the resistance patterns of INH, EMB, and STR in RIF-sensitive pulmonary tuberculosis (PTB) cases among children and adolescents.

METHODS

Seventy-five newly diagnosed RIF sensitive PTB cases up to 18 years of age were enrolled. Retreatment cases were excluded. Sputum/gastric aspirate sample of these patients were sent for culture in Mycobacterium Growth Indicator Tube (MGIT) followed by drug susceptibility testing and Line Probe Assay.

RESULTS

INH, EMB and STR resistance among RIF sensitive PTB cases was found to be 5.7%, 0% and 0.7% respectively. RIF resistance detected by CBNAAT was found to be 8.4%.

CONCLUSION

Detection of INH resistance is as important as detecting RIF resistance as prevalence of INH resistance in RIF sensitive PTB among children and adolescents up to 18 years is around 6%.

Multi-drug resistant and rifampin-resistant tuberculosis in transplant recipients

BACKGROUND

Management of multidrug-resistant (MDR) and rifampin-resistant (RR) tuberculosis is challenging. Data on transplant recipients is limited. We reviewed published literature to examine treatment choices, outcomes, and adverse effects from MDR-TB/RR-TB treatment in transplant recipients.

METHODS

Multiple databases from inception to 12/2022 were reviewed using the keywords "drug-resistant TB" or "drug-resistant tuberculosis" or "multidrug-resistant TB" or "multidrug-resistant tuberculosis". MDR-TB was defined as resistance to isoniazid (H) and rifampin (R), and RR if resistant to rifampin alone. Cases without patient-level data and reports which did not describe treatment and/or outcomes for MDR-TB were excluded.

RESULTS

A total of 12 patients (10 solid organ transplants and two hematopoietic cell transplants) were included. Of these, 11 were MDR-TB and one was RR-TB. Seven recipients were male. The median age was 41.5 (range 16-60) years. Pre-transplant evaluation for the majority (8/12, 66.7%) did not reveal a prior history of TB or TB treatment, but 9/12 were from TB intermediate or high-burden countries. Seven patients were initially treated with the quadruple first-line anti-TB regimen. Those who had early RR confirmation (5/12) via Xpert MTB/RIF assay were initiated on alternative therapies. Final regimens were individualized based on susceptibility profiles and tolerability. Adverse events were reported in seven recipients, including acute kidney injury (n = 3), cytopenias (n = 3), and jaundice (n = 2). Four recipients died, with two deaths attributable to TB. The remaining eight patients who survived had functioning allografts at the last follow-up.

CONCLUSIONS

MDR-TB treatment in transplant recipients is associated with many complications. Xpert MTB/RIF detected RR early and guided early empiric therapy.

Prevalence of Mycobacterium tuberculosis mutations associated with isoniazid and rifampicin resistance: A systematic review and meta-analysis

Tuberculosis (TB) is still one of the leading causes of worldwide death, especially following the emergence of strains resistant to isoniazid (INH) and rifampicin (RIF). This study aimed to systematically review published articles focusing on the prevalence of INH and/or RIF resistance-associated mutations of Mycobacterium tuberculosis isolates in recent years. Literature databases were searched using appropriate keywords. The data of the included studies were extracted and used for a random-effects model meta-analysis. Of the initial 1442 studies, 29 were finally eligible to be included in the review. The overall resistance to INH and RIF was about 17.2% and 7.3%, respectively. There was no difference between the frequency of INH and RIF resistance using different phenotypic or genotypic methods. The INH and/or RIF resistance was higher in Asia. The S315T mutation in KatG (23.7 %), C-15 T in InhA (10.7 %), and S531L in RpoB (13.5 %) were the most prevalent mutations. Altogether, the results showed that due to S531L in RpoB, S315T in KatG, and C-15 T in InhA mutations INH- and RIF-resistant M. tuberculosis isolates were widely distributed. Thus, it would be diagnostically and epidemiologically beneficial to track these gene mutations among resistant isolates.

Diagnosis of extrapulmonary tuberculosis by GeneXpert MTB/RIF Ultra assay

INTRODUCTION

Diagnosis of extrapulmonary tuberculosis (EPTB) is an arduous task owing to different anatomical locations, unusual clinical presentations, and sparse bacillary load in clinical specimens. Although GeneXpert® MTB/RIF is a windfall in TB diagnostics including EPTB, it yields low sensitivities but high specificities in many EPTB specimens. To further improve the sensitivity of GeneXpert®, GeneXpert® Ultra, a fully nested real-time PCR targeting IS6110, IS1081 and rpoB (Rv0664) has been endorsed by the WHO (2017), wherein melt curve analysis is utilized to detect rifampicin-resistance (RIF-R).

AREA COVERED

We described the assay chemistry/work design of Xpert Ultra and evaluated its performance in several EPTB types, that is, TB lymphadenitis, TB pleuritis, TB meningitis, and so on, against the microbiological reference standard or composite reference standard. Notably, Xpert Ultra exhibited better sensitivities than Xpert, but mostly at the compensation of specificity values. Moreover, Xpert Ultra exhibited low false-negative and false-positive RIF-R results, compared with Xpert. We also detailed other molecular tests, that is, Truenat MTBTM/TruPlus, commercial real-time PCR, line probe assay, and so on, for EPTB diagnosis.

EXPERT OPINION

A combination of clinical features, imaging, histopathological findings, and Xpert Ultra are adequate for definite EPTB diagnosis so as to initiate an early anti-tubercular therapy.

Diagnostic Performance of Different Laboratory Methods for the Detection of Extrapulmonary Tuberculosis

Accurate and appropriate extrapulmonary tuberculosis (EPTB) diagnosis remains challenging due to its paucibacillary nature, requirement of invasive collection procedures, and lack of sensitive tests. This study investigated the diagnostic performance of different methods for the diagnosis of EPTB. A total of 1340 EPTB specimens were collected from presumptive EPTB patients from four different hospitals between November 2015 and March 2017. The collected specimens were tested with AFB microscopy, culture, Xpert MTB/RIF assay (Xpert), and MTBDRplus assay. Among the 1340 EPTB specimens, 49 (3.66%), 141 (10.52%), 166 (12.39%), and 154 (11.49%) were positive in AFB microscopy, culture, Xpert MTB/RIF, and MTBDRplus assay, respectively. A total of 194 (14.9%) cases were found positive in at least one of these methods. Using culture as a reference standard, the sensitivity and specificity of AFB microscopy, Xpert MTB/RIF, and MTBDRplus assay were: 27.0%/99.1%, 83.7%/96.0%, and 79.4%/96.5%, respectively. Compared to the composite reference standard, the sensitivity of culture, AFB microscopy, Xpert MTB/RIF, and MTBDRplus assay was 72.7%, 25.3%, 85.6%, and 79.4%, respectively, with a specificity of 100% for all the methods. The Xpert MTB/RIF assay showed the highest sensitivity compared to other methods. Considering the short turnaround time and promising findings, Xpert MTB/RIF assay should be integrated into national TB guidelines as a routine diagnostic test.

Utility of line probe assay in detecting drug resistance and the associated mutations in patients with extrapulmonary tuberculosis in Addis Ababa, Ethiopia

Introduction

Molecular tests allow rapid detection of Mycobacterium tuberculosis and drug resistance in a few days. Identifying the mutations in genes associated with drug resistance may contribute to the development of appropriate interventions to improve tuberculosis control. So far, there is little information in Ethiopia about the diagnostic performance of line probe assay (LPA) and the M. tuberculosis common gene mutations associated with drug resistance in extrapulmonary tuberculosis. Thus, this study aimed to assess the frequency of drug resistance-associated mutations in patients with extrapulmonary tuberculosis (EPTB) and to compare the agreement and determine the utility of the genotypic in the detection of drug resistance in Addis Ababa, Ethiopia.

Methods

A cross-sectional study was conducted on stored M. tuberculosis isolates. The genotypic and phenotypic drug susceptibility tests were performed using LPA and BACTEC-MGIT-960, respectively. The common mutations were noted, and the agreement and the utility of the LPA were determined using the BACTEC-MGIT-960 as a gold standard.

Results

Of the 151 isolates, the sensitivity and specificity of MTBDRplus in detecting isoniazid resistance were 90.9% and 100%, respectively. While for rifampicin, it was 100% and 99.3% for sensitivity and specificity, respectively. The katG S315Tl was the most common mutation observed in 85.7% of the isoniazid-resistant isolates. In the case of rifampicin, the most common mutation (61.9%) was observed at position rpoB S531L. Mutations in the gyrA promoter region were strongly associated with Levofloxacin and Moxifloxacin resistance.

Conclusion

Line probe assay has high test performance in detecting resistance to anti-TB drugs in EPTB isolates. The MTBDRplus test was slightly less sensitive for the detection of isoniazid resistance as compared to the detection of rifampicin. The most prevalent mutations associated with isoniazid and rifampicin resistance were observed at katG S315Tl and rpoB S531L respectively. Besides, all the fluoroquinolone-resistant cases were associated with gyrA gene. Finally, a validation study with DNA sequencing is recommended.

Clinical characteristic, Common sites and Drug resistance profile in Culture-confirmed EPTB/ HIV co-infection patients, Southwest of China

OBJECTIVES

There are few reports on EPTB/HIV co-infection patients, especially the drug resistance profile of culture-confirmed EPTB. The purpose of our study was to analysis the clinical characteristic, common sites and drug resistance profile of culture-confirmed EPTB/HIV co-infection patients in recent years in southwest of China.

METHODS

A total of 201 EPTB/HIV co-infection cases were selected for this study. Patient demographic and clinical characteristics were collected. Mycobacterium tuberculosis drug sensitivity testing was performed using the microporousplate ratio method.

RESULTS

For the 2884 culture-confirmed EPTB cases recruited, patients were predominantly male1921/2884(66.6%). Mean age was 31years. Two hundred and one cases were EPTB/ HIV co-infection patients(7.0 %), from 201 cases male make up 84.6% (170/201), mean age was 42 years (range 13-86/year). During the 7-years period, the mean number of EPTB/ HIV co-infection cases was 29 per year(range 12-49/year) at this institution. Diarrhea, headache and fever were the most common presenting symptom.DST results showed the resistance to any anti-tuberculosis drug was observed in 62(30.8%) patient isolates, while multidrug-resistant TB and extensively drug-resistant TB were found in 14(7.0%) and 10(5.0%) patients, respectively. The distribution of EPTB tissue type mainly in Meningeal and Lymph node, varies between different genders.

CONCLUSIONS

The immune level of EPTB/HIV co-infected patients was low and most were in advanced AIDS stage. Mainly young male, and the site of EPTB was mainly in the Meningeal and Lymph node. The most common symptoms were diarrhea, headache and fever and high rates of drug resistance were found.

Xpert MTB/RIF Ultra and Xpert MTB/RIF assays for extrapulmonary tuberculosis and rifampicin resistance in adults

BACKGROUND

Xpert MTB/RIF Ultra (Xpert Ultra) and Xpert MTB/RIF are World Health Organization (WHO)-recommended rapid nucleic acid amplification tests (NAATs) widely used for simultaneous detection of Mycobacterium tuberculosis complex and rifampicin resistance in sputum. To extend our previous review on extrapulmonary tuberculosis (Kohli 2018), we performed this update to inform updated WHO policy (WHO Consolidated Guidelines (Module 3) 2020).

OBJECTIVES

To estimate diagnostic accuracy of Xpert Ultra and Xpert MTB/RIF for extrapulmonary tuberculosis and rifampicin resistance in adults with presumptive extrapulmonary tuberculosis.

SEARCH METHODS

Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, Web of Science, Latin American Caribbean Health Sciences Literature, Scopus, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, the International Standard Randomized Controlled Trial Number Registry, and ProQuest, 2 August 2019 and 28 January 2020 (Xpert Ultra studies), without language restriction.

SELECTION CRITERIA

Cross-sectional and cohort studies using non-respiratory specimens. Forms of extrapulmonary tuberculosis: tuberculous meningitis and pleural, lymph node, bone or joint, genitourinary, peritoneal, pericardial, disseminated tuberculosis. Reference standards were culture and a study-defined composite reference standard (tuberculosis detection); phenotypic drug susceptibility testing and line probe assays (rifampicin resistance detection).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias and applicability using QUADAS-2. For tuberculosis detection, we performed separate analyses by specimen type and reference standard using the bivariate model to estimate pooled sensitivity and specificity with 95% credible intervals (CrIs). We applied a latent class meta-analysis model to three forms of extrapulmonary tuberculosis. We assessed certainty of evidence using GRADE.

MAIN RESULTS

69 studies: 67 evaluated Xpert MTB/RIF and 11 evaluated Xpert Ultra, of which nine evaluated both tests. Most studies were conducted in China, India, South Africa, and Uganda. Overall, risk of bias was low for patient selection, index test, and flow and timing domains, and low (49%) or unclear (43%) for the reference standard domain. Applicability for the patient selection domain was unclear for most studies because we were unsure of the clinical settings. Cerebrospinal fluid Xpert Ultra (6 studies) Xpert Ultra pooled sensitivity and specificity (95% CrI) against culture were 89.4% (79.1 to 95.6) (89 participants; low-certainty evidence) and 91.2% (83.2 to 95.7) (386 participants; moderate-certainty evidence). Of 1000 people where 100 have tuberculous meningitis, 168 would be Xpert Ultra-positive: of these, 79 (47%) would not have tuberculosis (false-positives) and 832 would be Xpert Ultra-negative: of these, 11 (1%) would have tuberculosis (false-negatives). Xpert MTB/RIF (30 studies) Xpert MTB/RIF pooled sensitivity and specificity against culture were 71.1% (62.8 to 79.1) (571 participants; moderate-certainty evidence) and 96.9% (95.4 to 98.0) (2824 participants; high-certainty evidence). Of 1000 people where 100 have tuberculous meningitis, 99 would be Xpert MTB/RIF-positive: of these, 28 (28%) would not have tuberculosis; and 901 would be Xpert MTB/RIF-negative: of these, 29 (3%) would have tuberculosis. Pleural fluid Xpert Ultra (4 studies) Xpert Ultra pooled sensitivity and specificity against culture were 75.0% (58.0 to 86.4) (158 participants; very low-certainty evidence) and 87.0% (63.1 to 97.9) (240 participants; very low-certainty evidence). Of 1000 people where 100 have pleural tuberculosis, 192 would be Xpert Ultra-positive: of these, 117 (61%) would not have tuberculosis; and 808 would be Xpert Ultra-negative: of these, 25 (3%) would have tuberculosis. Xpert MTB/RIF (25 studies) Xpert MTB/RIF pooled sensitivity and specificity against culture were 49.5% (39.8 to 59.9) (644 participants; low-certainty evidence) and 98.9% (97.6 to 99.7) (2421 participants; high-certainty evidence). Of 1000 people where 100 have pleural tuberculosis, 60 would be Xpert MTB/RIF-positive: of these, 10 (17%) would not have tuberculosis; and 940 would be Xpert MTB/RIF-negative: of these, 50 (5%) would have tuberculosis. Lymph node aspirate Xpert Ultra (1 study) Xpert Ultra sensitivity and specificity (95% confidence interval) against composite reference standard were 70% (51 to 85) (30 participants; very low-certainty evidence) and 100% (92 to 100) (43 participants; low-certainty evidence). Of 1000 people where 100 have lymph node tuberculosis, 70 would be Xpert Ultra-positive and 0 (0%) would not have tuberculosis; 930 would be Xpert Ultra-negative and 30 (3%) would have tuberculosis. Xpert MTB/RIF (4 studies) Xpert MTB/RIF pooled sensitivity and specificity against composite reference standard were 81.6% (61.9 to 93.3) (377 participants; low-certainty evidence) and 96.4% (91.3 to 98.6) (302 participants; low-certainty evidence). Of 1000 people where 100 have lymph node tuberculosis, 118 would be Xpert MTB/RIF-positive and 37 (31%) would not have tuberculosis; 882 would be Xpert MTB/RIF-negative and 19 (2%) would have tuberculosis. In lymph node aspirate, Xpert MTB/RIF pooled specificity against culture was 86.2% (78.0 to 92.3), lower than that against a composite reference standard. Using the latent class model, Xpert MTB/RIF pooled specificity was 99.5% (99.1 to 99.7), similar to that observed with a composite reference standard. Rifampicin resistance Xpert Ultra (4 studies) Xpert Ultra pooled sensitivity and specificity were 100.0% (95.1 to 100.0), (24 participants; low-certainty evidence) and 100.0% (99.0 to 100.0) (105 participants; moderate-certainty evidence). Of 1000 people where 100 have rifampicin resistance, 100 would be Xpert Ultra-positive (resistant): of these, zero (0%) would not have rifampicin resistance; and 900 would be Xpert Ultra-negative (susceptible): of these, zero (0%) would have rifampicin resistance. Xpert MTB/RIF (19 studies) Xpert MTB/RIF pooled sensitivity and specificity were 96.5% (91.9 to 98.8) (148 participants; high-certainty evidence) and 99.1% (98.0 to 99.7) (822 participants; high-certainty evidence). Of 1000 people where 100 have rifampicin resistance, 105 would be Xpert MTB/RIF-positive (resistant): of these, 8 (8%) would not have rifampicin resistance; and 895 would be Xpert MTB/RIF-negative (susceptible): of these, 3 (0.3%) would have rifampicin resistance.

AUTHORS' CONCLUSIONS

Xpert Ultra and Xpert MTB/RIF may be helpful in diagnosing extrapulmonary tuberculosis. Sensitivity varies across different extrapulmonary specimens: while for most specimens specificity is high, the tests rarely yield a positive result for people without tuberculosis. For tuberculous meningitis, Xpert Ultra had higher sensitivity and lower specificity than Xpert MTB/RIF against culture. Xpert Ultra and Xpert MTB/RIF had similar sensitivity and specificity for rifampicin resistance. Future research should acknowledge the concern associated with culture as a reference standard in paucibacillary specimens and consider ways to address this limitation.

Tuberculous Scleritis and Multidrug Resistance

Purpose: To present a case of necrotizing sclerokeratitis in a patient with multidrug-resistant tuberculosis and study the challenges in diagnosis and management of anterior tuberculous scleritis.Methods: Retrospective observational case report and review of anterior tuberculous scleritis.Results: A 28-year-old woman, previously diagnosed as presumed tubercular panuveitis, presented with necrotizing sclerokeratitis and progressed to develop panophthalmitis. Laboratory investigations revealed multidrug-resistant Mycobacterium tuberculosis as the etiological agent. We reviewed cases of anterior tuberculous scleritis published in the literature, with regards to clinical features, microbiological investigations, treatment, and outcomes. Treatment includes standard antitubercular therapy, with or without systemic corticosteroids. Poor response to treatment is seen either due to delayed diagnosis or drug resistance, and the significance of the same is highlighted in our case.Conclusion: Diagnosis of tuberculous scleritis is a challenge. Therapeutic failure must alert the clinician for drug resistance which is diagnosed early, can prevent the devastating outcomes.

Molecular characterization and drug resistance patterns of Mycobacterium tuberculosis complex in extrapulmonary tuberculosis patients in Addis Ababa, Ethiopia

Background

Molecular characterization of Mycobacterium tuberculosis (MTB) is important to understand the pathogenesis, diagnosis, treatment, and prevention of tuberculosis (TB). However, there is limited information on molecular characteristics and drug-resistant patterns of MTB in patients with extra-pulmonary tuberculosis (EPTB) in Ethiopia. Thus, this study aimed to determine the molecular characteristics and drug resistance patterns of MTB in patients with EPTB in Addis Ababa, Ethiopia.

Methods

This study was conducted on frozen stored isolates of EPTB survey conducted in Addis Ababa, Ethiopia. A drug susceptibility test was performed using BACTEC-MGIT 960. Species and strain identification were performed using the Geno-Type MTBC and spoligotyping technique, respectively. Data were entered into the MIRU-VNTRplus database to assess the spoligotype patterns of MTB. Analysis was performed using SPSS version 23, and participants’ characteristics were presented by numbers and proportions.

Results

Of 151 MTB isolates, 29 (19.2%) were resistant to at least one drug. The highest proportion of isolates was resistant to Isoniazid (14.6%) and Pyrazinamide (14.6%). Nine percent of isolates had multidrug-resistant TB (MDR-TB), and 21.4% of them had pre-extensively drug-resistant TB (pre-XDR-TB). Among the 151 MTB isolates characterized by spoligotyping, 142 (94.6%) had known patterns, while 9 (6.0%) isolates were not matched with the MIRU-VNTRplus spoligotype database. Of the isolates which had known patterns, 2% was M.bovis while 98% M. tuberculosis. Forty-one different spoligotype patterns were identified. The most frequently identified SpolDB4 (SIT) wereSIT149 (21.2%), SIT53 (14.6%) and SIT26 (9.6%). The predominant genotypes identified were T (53.6%), Central Asia Strain (19.2%) and Haarlem (9.9%).

Conclusion

The present study showed a high proportion of MDR-TB and pre-XDR-TB among EPTB patients. The strains were mostly grouped into SIT149, SIT53, and SIT26. The T family lineage was the most prevalent genotype. MDR-TB and pre-XDR-TB prevention is required to combat these strains in EPTB. A large scale study is required to describe the molecular characteristics and drug resistance patterns of MTB isolates in EPTB patients.

Evaluation of genotype MTBDRplus V2 and genotype MTBDRsl V2 for the diagnosis of extrapulmonary tuberculosis in India

Microbiological diagnosis of extra-pulmonary tuberculosis (EPTB) has been one of the most difficult aspects of tuberculosis (TB) management. Availability of better imaging and diagnostic modalities has led to an increase in the number of diagnosed cases. The current upsurge in multidrug-resistant tuberculosis warrants routine testing of EPTB samples for resistance at baseline with shorter turn-around time. A total of 369 EPTB specimens were subjected to Ziehl-Neelsen (ZN) stain, liquid culture (LC) with phenotypic drug susceptibility testing, MTBDRplus V.2 and MTBDRsl V.2. The molecular categorisation of resistant specimens was further reconfirmed with sequencing. The sensitivity and specificity of MTBDRplus V.2 to detect Mycobacterium tuberculosis (MTB) when compared to ZN stain was 97.9% and 89.2%, respectively while it was 73.4% and 83.8%, respectively when compared to LC. Similarly, for MTBDRsl V.2, the sensitivity and specificity for detection of MTB when compared with ZN was 95.6% and 91.9%, respectively and 75% and 89.2%, respectively when compared to LC. In smear-positive specimens, 94% (141/150) and 86% (129/150) valid results were observed in MTBDRplus V.2 and MTBDRsl V.2, respectively. The utilisation of both MTBDRplus V.2 and MTBDRsl V.2 for the diagnosis of smear-positive EPTB specimens would be useful in programmatic management of TB in high-burden settings.

Use of Xpert MTB/RIF and Xpert Ultra in extrapulmonary tuberculosis

INTRODUCTION

Tuberculosis (TB) remains a major global health burden. There still remains a large gap between the notified and estimated incident cases. Extrapulmonary (EP) TB represents 15% of all TB cases and the diagnosis is more challenging due to the paucity of the organism. Smear microscopy is often insensitive and culture methods are prolonged. With the introduction of Xpert MTB/RIF and more recently Xpert Ultra, this has changed TB diagnostics by providing a rapid accessible platform to diagnose TB and identify rifampicin resistance within 2 h.

AREAS COVERED

The diagnostic accuracy and the clinical role of Xpert MTB/RIF and Xpert Ultra in the different forms of EPTB.

EXPERT OPINION

Whilst significant advances have been made in TB diagnostics, there is still a need to optimize the diagnostic yield of Xpert MTB/RIF and Xpert Ultra in EPTB samples. Research is needed to facilitate standardization and optimal preparation of samples as well as understanding the role of Xpert MTB/RIF and Xpert Ultra in different burden settings. Alongside the current GeneXpert platform, the launch of rapid second-line drug resistance polymerase chain reactions and whole genome sequencing may help tackle the global health burden with a more comprehensive diagnostic approach and appropriate treatment.

Diagnostic Evaluation of Non-Interpretable Results Associated with rpoB Gene in Genotype MTBDRplus Ver 2.0

Background

Line probe assay (LPA) is standard diagnostic tool to detect multidrug resistant tuberculosis. Non-interpretable (NI) results in LPA (complete missing or light wild-type 3 and 8 bands with no mutation band in rpoB gene region) poses a diagnostic challenge.

Methods

Sputum samples obtained between October 2016 and July 2017 at the Intermediate Reference Laboratory, All India Institute of Medical Sciences Hospital, New Delhi, India were screened. Smear-positive and smear-negative culture-positive specimens were subjected to LPA Genotype MTBDRplus Ver 2.0. Smear-negative with culture-negative and culture contamination were excluded. LPA NI samples were subjected to phenotypic drug susceptibility testing (pDST) using MGIT-960 and sequencing.

Results

A total of 1,614 sputum specimens were screened and 1,340 were included for the study (smear-positive [n=1,188] and smear-negative culture-positive [n=152]). LPA demonstrated 1,306 (97.5%) valid results with TUB (Mycobacterium tuberculosis) band, 24 (1.8%) NI, three (0.2%) valid results without TUB band, and seven (0.5%) invalid results. Among the NI results, 22 isolates (91.7%) were found to be rifampicin (RIF) resistant and two (8.3%) were RIF sensitive in the pDST. Sequencing revealed that rpoB mutations were noted in all 22 cases with RIF resistance, whereas the remaining two cases had wild-type strains. Of the 22 cases with rpoB mutations, the most frequent mutation was S531W (n=10, 45.5%), followed by S531F (n=6, 27.2%), L530P (n=2, 9.1%), A532V (n=2, 9.1%), and L533P (n=2, 9.1%).

Conclusion

The present study showed that the results of the Genotype MTBDRplus assay were NI in a small proportion of isolates. pDST and rpoB sequencing were useful in elucidating the cause and clinical meaning of the NI results.

Xpert MTB/RIF assay for the diagnosis of rifampicin resistance in different regions: a meta-analysis

Background

To estimate the diagnostic accuracy of Xpert MTB/RIF for rifampicin resistance in different regions, a meta-analysis was carried out.

Methods

Several databases were searched for relevant studies up to March 3, 2019. A bivariate random-effects model was used to estimate the diagnostic accuracy.

Results

We identified 97 studies involving 26,037 samples for the diagnosis of rifampicin resistance. The pooled sensitivity, specificity and AUC of Xpert MTB/RIF for rifampicin resistance detection were 0.93 (95% CI 0.90–0.95), 0.98 (95% CI 0.96–0.98) and 0.99 (95% CI 0.97–0.99), respectively. For different regions, the pooled sensitivity were 0.94(95% CI 0.89–0.97) and 0.92 (95% CI 0.88–0.94), the pooled specificity were 0.98 (95% CI 0.94–1.00) and 0.98 (95% CI 0.96–0.99), and the AUC were 0.99 (95% CI 0.98–1.00) and 0.99 (95% CI 0.97–0.99) in high and middle/low income countries, respectively. The pooled sensitivity were 0.91 (95% CI 0.87–0.94) and 0.91 (95% CI 0.86–0.94), the pooled specificity were 0.98 (95% CI 0.96–0.99) and 0.98 (95% CI 0.96–0.99), and the AUC were 0.98 (95% CI 0.97–0.99) and 0.99 (95% CI 0.97–0.99) in high TB burden and middle/low prevalence countries, respectively.

Conclusions

The diagnostic accuracy of Xpert MTB/RIF for rifampicin resistance detection was excellent.

Rapid molecular diagnostics for multi-drug resistant tuberculosis in India

INTRODUCTION

Rapid molecular diagnostic methods help in the detection of TB and Rifampicin resistance. These methods detect TB early, are accurate and play a crucial role in reducing the burden of drug resistant tuberculosis. Areas covered: This review analyses rapid molecular diagnostic tools used in the diagnosis of MDR-TB in India, such as the Line Probe Assay and GeneXpert. We have discussed the burden of MDR-TB and the impact of recent diagnostic tools on case detection and treatment outcomes. This review also discusses the costs involved in establishing these new techniques in India. Expert commentary: Molecular methods have considerable advantages for the programmatic management of drug resistant TB. These include speed, standardization of testing, potentially high throughput and reduced laboratory biosafety requirements. There is a desperate need for India to adopt modern, rapid, molecular tools with point-of-care tests being currently evaluated. New molecular diagnostic tests appear to be cost effective and also help in detecting missing cases. There is enough evidence to support the scaling up of these new tools in India.