Detection of multidrug and extensively drug-resistance and mutation pattern in geriatric patients from North Indian referral institute

INTRODUCTION

Geriatric population are predisposed to reactivation to tuberculosis (TB) and multi-drug resistance (MDR) due to deteriorated immune system. Limited data is available in this population hence present study is undertaken to study drug resistance and associated mutations among geriatric presumptive DR-TB patients by genotypic methods METHODS: From October 2011 to December 2018, demographic characteristics of enrolled patients was collected. Smear-positive processed sputum samples were subjected directly while cultures positive for Mycobacterium Tuberculosis (MTB) from smear-negative pulmonary and all extra-pulmonary samples were subjected to LPA. The LPA used were Genotype MTBDR plus (1st line LPA) for detection of susceptibility to rifampicin (RIF) and isoniazid (INH) and Genotype MTBDR sl (2nd line LPA), for susceptibility to fluoroquinolones (FQ) and aminoglycosides (AG).

RESULTS

Total of 2041 samples were received from presumptive MDR-TB patients above 60 years of age during study period, of which 1406; 68.9% were within 60-70 year followed by 495; 24.3% within 71-80 year and 140; 6.9% more than 80 years. Total of 1055 MTB were detected, of which those diagnosed as RIF resistant were 117/1055; 11.2% including 89/1055; 8.5% MDR-TB and resistance to INH was in 84/1055; 8%. Total 67, 2nd line LPA gave valid results, of which 19/67 (28.4%) isolates were resistant to only FQ, and one isolate was resistant to AG.

CONCLUSION

Study finding highlights need for dedicated efforts for diagnosis, and treatment of geriatric tuberculosis. Suitable intervention at programmatic country level at country will help in strengthening tuberculosis control strategies in this population.

Fluorescein Diacetate Vital staining for detecting viability of acid-fast bacilli in sputum of pulmonary tuberculosis patients

OBJECTIVE

To compare the performance of the Fluorescein diacetate (FDA) vital staining method with Ziehl-Neelsen staining method in detecting the viability of acid-fast bacilli using MGIT culture as "reference standard".

METHODS

This was a single centre prospective observational study conducted from October 2015 to November 2016. Microbiologically confirmed ZN-Smear positive (3+) sputum specimens were obtained from 30 pulmonary tuberculosis patients taking anti-tuberculosis treatment at DOTS centre of NITRD, New Delhi. Patients were made available to collect the first baseline sputum sample before commencing treatment, and an early morning sputum sample was collected as per RNTCP guidelines. After starting treatment, sputum specimens were collected weekly in the first month and thereafter twice-weekly until 18th week. All sputum specimens from patients receiving anti-tuberculosis treatment were examined using Ziehl-Neelsen (ZN) smear microscopy, FDA vital staining, and MGIT culture.

RESULT

Out of 360 follow up sputum specimens collected from 30 adult microbiologically confirmed ZN- Smear (3+) pulmonary tuberculosis patients, 146 were ZN-positive and 130 FDA-positive. Of 130 FDA-positive sputum samples, mycobacteria tuberculosis (MTB) growth was found in 116 sputum samples, of which 116 sputum specimens were positive for FDA. Additionally, 14 culture-negative specimens were FDA positive. No FDA-negative sputum samples were positive for MGIT culture. Among ZN positive specimens, FDA had 100% sensitivity and 85.3% specificity with an accuracy of 96.58% for the detection of viable mycobacteria. Among ZN negative sputum specimens, FDA had comparatively high specificity (95.7%). Using positive MGIT culture as a reference for viability, negative predictive value (NPV) and positive predictive value (PPV) from FDA vital staining method were found to be 100 and 89% respectively.

CONCLUSION

FDA staining is a simple and rapid tool for identifying viable MTB bacilli. Because of its excellent NPV and encouraging specificity, FDA staining is useful to identify patients with non-viable bacilli (FDA negative) among retreatment cases at diagnosis and patients on anti-tuberculosis treatment for both drug-sensitive and drug-resistant tuberculosis for follow up for the response of treatment.

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.

Correlation of inhA mutations and ethionamide susceptibility: Experience from national reference center for tuberculosis

Background:

Detection of ethionamide (ETH) resistance is crucial as it is part of antitubercular regime. It is crucial to examine the role of inhA gene mutations as a surrogate marker for the detection of ETH resistance, in the Indian context. The present retrospective study was designed with this objective.

Subjects and Methods:

The study was conducted in National Reference Laboratory within the tertiary care institute from January 1, 2018, to June 30, 2019, over 18 months duration. A total of 6612 sputum samples from presumptive multidrug-resistant tuberculosis (TB) patients were received from four districts of Delhi, outdoor and inpatients. Line probe assay (LPA) was performed for smear-positive or culture-positive samples for Mycobacterium tuberculosis. All isolates found to be INH resistant by LPA were cultured and phenotypic susceptibility to ETH was conducted for selected isolates as per the guidelines.

Results:

A total of 246 isolates were analyzed, for which phenotypic susceptibility to ETH and mutations in inhA were available. ETH resistance was detected among 87/108 (80.5%) isolates with inhA mutation. Sensitivity and specificity of inhA mutation for detection of ETH resistance were 80.5% and 83.8%, respectively. No inhA mutation was detected in 29/116 (25%) ETH-resistant isolates in our study, whereas ETH was found to be phenotypically susceptible in spite of the presence of inhA mutation among 21/130 (16.1%) isolates.

Conclusions:

Mutations in inhA gene in LPA predict ETH resistance with fairly good sensitivity and specificity. However, it is imperative to perform phenotypic detection of ETH resistance at proper concentration, in addition to detecting inhA mutation.

Detection of isoniazid, fluoroquinolone, ethionamide, amikacin, kanamycin, and capreomycin resistance by the Xpert MTB/XDR assay: a cross-sectional multicentre diagnostic accuracy study

BACKGROUND

The WHO End TB Strategy requires drug susceptibility testing and treatment of all people with tuberculosis, but second-line diagnostic testing with line-probe assays needs to be done in experienced laboratories with advanced infrastructure. Fewer than half of people with drug-resistant tuberculosis receive appropriate treatment. We assessed the diagnostic accuracy of the rapid Xpert MTB/XDR automated molecular assay (Cepheid, Sunnyvale, CA, USA) to overcome these limitations.

METHODS

We did a prospective study involving individuals presenting with pulmonary tuberculosis symptoms and at least one risk factor for drug resistance in four sites in India (New Delhi and Mumbai), Moldova, and South Africa between July 31, 2019, and March 21, 2020. The Xpert MTB/XDR assay was used as a reflex test to detect resistance to isoniazid, fluoroquinolones, ethionamide, amikacin, kanamycin, and capreomycin in adults with positive results for Mycobacterium tuberculosis complex on Xpert MTB/RIF or Ultra (Cepheid). Diagnostic performance was assessed against a composite reference standard of phenotypic drug-susceptibility testing and whole-genome sequencing. This study is registered with ClinicalTrials.gov, number NCT03728725.

FINDINGS

Of 710 participants, 611 (86%) had results from both Xpert MTB/XDR and the reference standard for any drug and were included in analysis. Sensitivity for Xpert MTB/XDR detection of resistance was 94% (460 of 488, 95% CI 92-96) for isoniazid, 94% (222 of 235, 90-96%) for fluoroquinolones, 54% (178 of 328, 50-61) for ethionamide, 73% (60 of 82, 62-81) for amikacin, 86% (181 of 210, 81-91) for kanamycin, and 61% (53 of 87, 49-70) for capreomycin. Specificity was 98-100% for all drugs. Performance was equivalent to that of line-probe assays. The non-determinate rate of Xpert MTB/XDR (ie, invalid M tuberculosis complex detection) was 2·96%.

INTERPRETATION

The Xpert MTB/XDR assay showed high diagnostic accuracy and met WHO's minimum target product profile criteria for a next-generation drug susceptibility test. The assay has the potential to diagnose drug-resistant tuberculosis rapidly and accurately and enable optimum treatment.

FUNDING

German Federal Ministry of Education and Research through KfW, Dutch Ministry of Foreign Affairs, and Australian Department of Foreign Affairs and Trade.

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

Background

Near-patient access to appropriate tests is a major obstacle for the efficient diagnosis of tuberculosis (TB) and associated drug resistance.

Methods

We 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).

Results

Trans-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)).

Conclusions

This 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.

The adoption of bio-safe “TB Concentration & Transport” kit by Microscopy Centres can potentially overcome the challenge of transporting infectious sputum to central laboratories and provide universal DST services to TB subjects residing in remote areas.https://bit.ly/2QrQ5qL

Multicentric validation of indigenous molecular test Truenat™ MTB for detection of Mycobacterium tuberculosis in sputum samples from presumptive pulmonary tuberculosis patients in comparison with reference standards

Background & objectives:

Early case detection is essential to interrupt transmission and to prevent further spread of tuberculosis (TB) in high endemic settings. Nucleic acid amplification tests (NAATs) with visual read-outs are ideal as point-of-care tests. Truenat™ MTB is an indigenous chip-based NAAT for detection of Mycobacterium tuberculosis, which involves extraction of DNA and real-time polymerase chain reaction (PCR) using portable, automated, battery-operated instruments. The current multicentric study was aimed to evaluate Truenat for detection of MTB in sputum samples obtained from patients with presumptive pulmonary TB with reference to culture as gold standard and Xpert as a comparator.

Methods:

The study was conducted at four sites, namely ICMR-National Institute for Research in Tuberculosis, Chennai; All India Institute of Medical Sciences, New Delhi; ICMR-National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra; and National Institute of TB and Respiratory Diseases, New Delhi. Patients suspected to have TB were screened for eligibility. Two sputum samples were collected from each patient. Tests included smear, Xpert and Truenat directly from the sputum sample and culture by Lowenstein-Jensen (L-J) medium and MGIT960 from decontaminated pellets. Sample used for Truenat assay was coded. Resolution of Truenat false positives was done using an in-house PCR with TRC₄ primers.

Results:

The study enrolled 2419 presumptive TB patients after screening 2465 patients, and 3541 sputum samples were collected from the enrolled patients. Results of 2623 samples were available for analysis. Truenat showed a positivity rate of 48.5 per cent as compared to 37.0 per cent by Xpert. The sensitivities of Truenat and Xpert were was 88.3 and 79.7 per cent, respectively in comparison with culture.

Interpretation & conclusions:

Truenat MTB identified more positives among culture-confirmed samples than Xpert and had higher sensitivity. In addition, other advantageous operational features of Truenat MTB were identified which would be useful in field settings.

Validation of an indigenous assay for rapid molecular detection of rifampicin resistance in presumptive multidrug-resistant pulmonary tuberculosis patients

Background & objectives:

There is a need for an affordable, easy, high-sensitivity test usable at the peripheral health facility for diagnosis of drug-resistant (DR) tuberculosis (TB) to interrupt disease transmission. Nucleic acid amplification tests (NAATs) for early detection of DR-TB are ideal to bring testing near to the patient. Truenat™ MTB (Mycobacterium tuberculosis) and Truenat™ MTB-RIF (rifampicin) is an indigenous chip-based real-time polymerase chain reaction (PCR) based test for detection of multidrug-resistant (MDR) TB. The test involves extraction of DNA using automated, battery operated Trueprep instrument and real-time PCR performed on the Truelab analyzer. We report here multicentric validation of Truenat MTB-RIF for detection of DR-TB in suspected DR-TB patients.

Methods:

Consecutive patients aged 18-65 yr, with symptoms suggestive of TB and with a history of previous treatment, reporting to the National TB Elimination Programme (NTEP) clinics under four national institutes, namely AIIMS (All India Institute of Medical Sciences, New Delhi), NITRD (National Institute of Tuberculosis and Respiratory Diseases, New Delhi), NIRT (National Institute for Research in Tuberculosis, Chennai) and ICMR-National JALMA Institute for Leprosy and other Mycobacterial Diseases, Agra, were included in the study. Two sputum samples (one spot and one morning) were collected from each patient, after obtaining informed written consent. The samples were subjected to smear, GeneXpert and MGIT 960 culture (and drug susceptibility testing to RIF) (surrogate for MDR-TB) to serve as reference tests. The samples were coded to ensure blinding and subjected to Truenat MTB-RIF. Truenat MTB-RIF Version 1.5 was used for testing 1084 samples for RIF resistance, while Version 2.0 was used to test another 1201 samples.

Results:

Truenat MTB-RIF Version 1.5 in comparison with comprehensive laboratory reference standards yielded sensitivity and specificity of 76.2 and 94.7 per cent, respectively for the detection of RIF resistance in 1084 samples, collected across four sites. Based on the analysis of discordant samples, Version 2.0 of Truenat was developed by the manufacturer and this was further tested on additional 1201 samples, yielding a sensitivity of 87.5 per cent and specificity of 99.5 per cent.

Interpretation & conclusions:

Multicentric trial of Truenat™ MTB-RIF demonstrated a great potential of this point of care NAAT for detection of MDR-TB. The test would be useful in limited resource settings and inaccessible areas without need for any additional infrastructure.

Evaluation of 'TBDetect' sputum microscopy kit for improved detection of Mycobacterium tuberculosis: a multi-centric validation study

OBJECTIVES

The present study aimed to evaluate the performance of the 'TBDetect' kit-based bio-safe fluorescent microscopy filter (BioFM-Filter) microscopy in comparison with direct smear microscopy and culture for the detection of pulmonary tuberculosis (TB) in a multi-centric setting in India.

METHODS

The TBDetect kit enables sputum concentration through filtration using the BioFM-Filter for improved and bio-safe smear microscopy. We evaluated the performance of the TBDetect kit in a six-site multi-centric validation study on sputum collected from 2086 presumptive TB patients.

RESULTS

The combined positivity of TBDetect microscopy performed on these sputum samples was 20% (n = 417/2086) vs 16.1% of light-emitting diode fluorescence microscopy (LED-FM, n = 337/2086) and 16% of Ziehl Neelsen (ZN) smear microscopy (n = 333/2086). The increment in positivity of TBDetect over both LED-FM and ZN smears was significant (p < 0.001). The overall sensitivity of TBDetect for six sites was ~55% (202/367, 95% confidence interval (CI): 50, 60%) vs 52% (191/367, 95% CI: 47, 57%) for LED-FM (p 0.14) and 50.9% (187/367, 95% CI: 46, 56%) for ZN smear (p < 0.05), using Mycobacterium Growth Indicator Tube culture (MGIT, n = 1949, culture positive, n = 367) as the reference standard. A bio-safety evaluation at six sites confirmed efficient sputum disinfection by TBDetect; 99.95% samples (1873/1874) were sterile after 42 days of incubation. Scientists and technicians at the study sites indicated the ease of use and convenience of TBDetect microscopy during feedback.

CONCLUSIONS

TBDetect added value to the smear microscopy test due to its improved performance, convenience and user safety. These findings indicate that equipment-free TBDetect technology has the potential to improve TB diagnosis in basic laboratory settings by leveraging on the existing nationwide network of designated microscopy centres and primary healthcare centres.

Disposal of the large volume of sputum positive for Mycobacterium tuberculosis by using microwave sterilisation technology as an alternative to traditional autoclaving in a tertiary respiratory care hospital in Delhi, India

Background

Everyday, tuberculosis hospitals collect enormous amount of sputum containing viable Mycobacterium tuberculosis bacilli, the disposal of which is a challenging task. Chemical (5% phenol) and physical (autoclaving) disinfection methods involve cost, space and cause further environmental degradation. Over the years, use of microwave for sterilisation of biomedical waste has become widespread. However, its efficacy to sterilise large volume of M. tuberculosis positive sputum has never been investigated.

Aim

To evaluate the effectiveness of microwave in sterilising large volumes of M. tuberculosis positive sputum samples.

Methods

226 sputum samples positive for M. tuberculosis were checked by Ziehl-Neelsen staining and liquid culture (MGIT ™) both before and after microwaving. χ² test was performed, and p-value <0.05 was considered significant.

Findings

Before microwaving, samples containing acid fast bacilli (AFB) and live M. tuberculosis bacilli were 93.8% and 95% (≈94.7%) respectively; which came down to 14.2% (32) and <1% (≈0.9%) in post microwave. In the 32 post-microwave AFB positive samples, bacilli appeared apoptotic, decreased in size, fragmented, loosely arranged and were easily missed as stain artefacts. Their beaded appearance was not appreciable. Background pus cells were of smaller size, did not take up methylene blue stain properly, and multilobed nuclear material was missing.

Conclusion

The study shows efficacy of microwave as an alternative sterilisation method for large volume sputum samples containing M. tuberculosis bacilli. Microwave can become an effective sterilisation method, especially for isolated tuberculosis care centres in countries which struggle for disposal of sputum, the biomedical waste.

Emerging trends in microbiological diagnostics in children

The targets of the WHO's End TB Strategy and the United Nations' (UN) Sustainable Development Goals (SDGs) have been expanded to"Find. Treat. All #EndTB" with universal access to TB diagnosis, treatment and care by 2022 in an effort to end the global TB epidemic. Trends to achieve the above targets in children have led to greater emphasis on the newer diagnostics paving way to microbiological confirmation and universal drug sensitivity in children.

Development and evaluation of novel bio-safe filter paper-based kits for sputum microscopy and transport to directly detect Mycobacterium tuberculosis and associated drug resistance

India has the highest burden of Tuberculosis (TB) and multidrug-resistant TB (MDR-TB) worldwide. Innovative technology is the need of the hour to identify these cases that remain either undiagnosed or inadequately diagnosed due to the unavailability of appropriate tools at primary healthcare settings. We developed and evaluated 3 kits, namely ‘TB Detect’ (containing BioFM-Filter device), ‘TB Concentration and Transport’ (containing Trans-Filter device) and ‘TB DNA Extraction’ kits. These kits enable bio-safe equipment-free concentration of sputum on filters and improved fluorescence microscopy at primary healthcare centres, ambient temperature transport of dried inactivated sputum filters to central laboratories and molecular detection of drug resistance by PCR and DNA sequencing (Mol-DST). In a 2-site evaluation (n = 1190 sputum specimens) on presumptive TB patients, BioFM-Filter smear exhibited a significant increase in positivity of 7% and 4% over ZN smear and LED-FM smear (p<0.05), respectively and an increment in smear grade status (1+ or 2+ to 3+) of 16% over ZN smear and 20% over LED-FM smear. The sensitivity of Mol-DST in presumptive MDR-TB and XDR-TB cases (n = 148) was 90% for Rifampicin (95% confidence interval [CI], 78–96%), 84% for Isoniazid (95% CI, 72–92%), 83% for Fluoroquinolones (95% CI, 66–93%) and 75% for Aminoglycosides (95% CI, 35–97%), using phenotypic DST as the reference standard. Test specificity was 88–93% and concordance was ~89–92% (κ value 0.8–0.9). The patient-friendly kits described here address several of the existing challenges and are designed to provide ‘Universal Access’ to rapid TB diagnosis, including drug-resistant disease. Their utility was demonstrated by application to sputum at 2 sites in India. Our findings pave the way for larger studies in different point-of-care settings, including high-density urban areas and remote geographical locations.

Early efficacy and safety of Bedaquiline and Delamanid given together in a "Salvage Regimen" for treatment of drug-resistant tuberculosis

BACKGROUND

Drug-Resistant Tuberculosis (DR-TB) patients for whom a WHO recommended regimen along with Bedaquiline (BDQ) cannot be prescribed, Delamanid (DLM) was added along with other drugs to provide a "Salvage Regimen". The experience of the Institute in respect of early efficacy and safety of both drugs given together is presented.

OBJECTIVE

To ascertain the early efficacy, safety and tolerability of Bedaquline and Delamanid given together as a part of salvage regimen.

METHODS

BDQ and DLM were used together to make regimens along with other drugs where four effective anti TB drugs could not be prescribed as per WHO recommendations. Patients were followed up for sputum smear and culture conversion and adverse events during the treatment.

RESULTS

In this cohort study, 53 DR-TB patients (Median age-24) were initiated on regimens containing both BDQ and DLM. Sputum smear conversion was seen in 35% and 94% patients at the end of 1st week and 3rd month respectively. 84% patients had culture conversion at the end of 4th month. 29 adverse events (AE) were reported among 17 patients and there were 11 deaths. QTc prolongation more than 500 MS was seen in only 1 patient.

CONCLUSION

BDQ and DLM given together in a salvage regimen is efficacious with low rate of adverse events. The combination provides hope to DR-TB patients with limited treatment options and should be provided as a life saving option.

Aptamer-Based TB Antigen Tests for the Rapid Diagnosis of Pulmonary Tuberculosis: Potential Utility in Screening for Tuberculosis

Pulmonary tuberculosis is the most common manifestation of tuberculosis, and to this day, sputum smear microscopy remains the most widely used diagnostic test in resource-limited settings despite its suboptimal sensitivity. Here we report the development of two DNA aptamer-based diagnostic tests, namely aptamer linked immobilized sorbent assay (Aptamer ALISA) and electrochemical sensor (ECS), for the direct detection of a TB biomarker HspX in sputum. First we compared the performance of Aptamer ALISA with anti-HspX polyclonal antibody-based enzyme linked immunosorbent assay (Antibody ELISA) in a blinded study of 314 sputum specimens. Aptamer ALISA displayed a high sensitivity of 94.1% (95% CI 86.8-98%) as compared to 68.2% sensitivity (95% CI 57.2-77.9%) of Antibody ELISA ( p-value < 0.05) using culture as the reference standard without compromising test specificity of 100%. Out of nine smear-negative culture-positive samples, six were positive by Aptamer ALISA and only two were detected by Antibody ELISA. ALISA detected as positive 80 of 85 culture-positive TB as compared to 57 of 81 diagnosed as TB by X-ray ( p-value < 0.0001). These findings demonstrate the superiority of the aptamer-based test over smear microscopy, antibody-based ELISA, and chest X-ray for TB detection ( p-value < 0.0001 for all). Further, we have developed a ∼30 min point-of-care ECS test that discriminates between tuberculous and nontuberculous sputum with a sensitivity of ∼92.3% and specificity of 91.2%. The tests developed in the current study cost ∼$1-3/test and have potential utility in active case finding in high-risk groups and screening for pulmonary TB among presumptive TB subjects.

Recurrence of tuberculosis among newly diagnosed sputum positive pulmonary tuberculosis patients treated under the Revised National Tuberculosis Control Programme, India: A multi-centric prospective study

Introduction

There is lack of information on the proportion of new smear—positive pulmonary tuberculosis (PTB) patients treated with a 6-month thrice-weekly regimen under Revised National Tuberculosis Control Programme (RNTCP) who develop recurrent TB after successful treatment outcome.

Objective

To estimate TB recurrence among newly diagnosed PTB patients who have successfully completed treatment and to document endogenous reactivation or re-infection. Risk factors for unfavourable outcomes to treatment and TB recurrence were determined.

Methodology

Adult (aged ≥ 18 yrs) new smear positive PTB patients initiated on treatment under RNTCP were enrolled from sites in Tamil Nadu, Karnataka, Delhi, Maharashtra, Madhya Pradesh and Kerala. Those declared “treatment success” at the end of treatment were followed up with 2 sputum examinations each at 3, 6 and 12 months after treatment completion. MIRU-VNTR genotyping was done to identify endogenous re-activation or exogenous re-infection at TB recurrence. TB recurrence was expressed as rate per 100 person-years (with 95% confidence interval [95%CI]). Regression models were used to identify the risk factors for unfavourable response to treatment and TB recurrence.

Results

Of the1577 new smear positive PTB patients enrolled, 1565 were analysed. The overall cure rate was 77% (1207/1565) and treatment success was 77% (1210 /1565). The cure rate varied from 65% to 86%. There were 158 of 1210 patients who had TB recurrence after treatment success. The pooled TB recurrence estimate was 10.9% [95%CI: 0.2–21.6] and TB recurrence rate per 100 person–years was 12.7 [95% CI: 0.4–25]. TB recurrence per 100 person–years varied from 5.4 to 30.5. Endogenous reactivation was observed in 56 (93%) of 60 patients for whom genotyping was done. Male gender was associated with TB recurrence.

Conclusion

A substantial proportion of new smear positive PTB patients successfully treated with 6 –month thrice-weekly regimen have TB recurrence under program settings.

Amplification of Hsp 65 gene and usage of restriction endonuclease for identification of non tuberculous rapid grower mycobacterium

BACKGROUND

The rapid grower mycobacteria have emerged as significant group of human pathogen amongst the Runyon group IV organisms that are capable of causing infection in both the healthy and immunocompromised hosts. Study aimed to identification of species amongst rapid grower non tuberculous mycobacterial isolates by polymerase chain reaction - restriction enzyme analysis (PRA). Analysis and comparison of results with standard biochemical tests.

METHODS

Rapid grower non tuberculous mycobacteria had been collected from liquid culture section during the study period. All isolates were identified by conventional biochemical tests. A 441bp fragment of hsp65 genes was amplified and digested by two restriction enzymes, BstEII and HaeIII. Digested products were analyzed using polyacrilamid gel electrophoresis (PAGE).

RESULTS

During study, 121 rapid grower mycobacterial isolates were subjected for species identification. Isolates were obtained from pulmonary samples (72) and extrapulmonary samples (49). In the PRA test 8 different types of rapid grower mycobacteria were identified after analyzing the fragments generated through restriction enzymes. Mycobacterium chelonae (57/121) was the most common isolate in pulmonary and extrapulmonary samples. Mycobacterium fortuitum (42), Mycobacterium abscessus (11), Mycobacterium immunogen (06), Mycobacterium peregrinum (02), Mycobacterium smegmatis (01), Mycobacterium wolinskyi (01), Mycobacterium goodii (01) were identified as other species of rapid grower non tuberculous mycobacteria.

CONCLUSION

PRA is a rapid and accurate system for the identification of species of non tuberculous mycobacteria. Results of PRA and biochemical tests are concordant up to 98%.

Drug resistance detection and mutation patterns of multidrug resistant tuberculosis strains from children in Delhi

A total of 312 sputum samples from pediatric patients presumptive of multidrug resistant tuberculosis were tested for the detection of drug resistance using the GenoTypeMTBDRplus assay. A total of 193 (61.8%) patients were smear positive and 119 (38.1%) were smear negative by Ziehl–Neelsen staining. Line probe assay (LPA) was performed for 208 samples/cultures (193 smear positive samples and 15 cultures from smear negative samples). Valid results were obtained from 198 tests. Of these, 125/198 (63.1%) were sensitive to both rifampicin (RIF) and isoniazid (INH). 73/198 (36.9%) were resistant to at least INH/RIF, out of which 49 (24.7%) were resistant to both INH and RIF (multidrug resistant). Children with tuberculosis are often infected by someone close to them, so strengthening of contact tracing in the program may help in early diagnosis to identify additional cases within the household. There is a need to evaluate newer diagnostic assays which have a high sensitivity in the case of smear negative samples, additional samples other than sputum among young children not able to expectorate, and also to fill the gap between estimated and reported cases under the program.

Isoniazid resistance among rifampicin-susceptible Mycobacterium tuberculosis isolates from tuberculosis patients

OBJECTIVE/BACKGROUND

With the introduction of novel molecular techniques that rely on rifampicin (RIF) susceptibility, resistance to isoniazid (INH) or other first-line drugs remains undetected. Such patients are prescribed first-line antituberculosis therapy and are on RIF monodrug therapy during the continuation phase, which may lead to therapeutic failure and emergence of multidrug resistance. We aimed to study INH resistance among RIF-susceptible Mycobacterium tuberculosis (MTB) isolates from retreatment patients.

METHODS

The Drug Susceptibility Testing data for four first-line drugs (streptomycin [SM], INH, RIF, and ethambutol [EMB]) using BACTEC MGIT 960 (Becton Dickinson, Franklin 124 Lakes, NJ ,USA) and for two drugs (INH and RIF) using line probe assay was analyzed retrospectively at the Department of Microbiology, National Institute of Tuberculosis and Respiratory Diseases (New Delhi, India).

RESULTS

We analyzed 4910 drug susceptibility results performed using the BACTEC MGIT960 liquid culture system from 2009 to 2015. We found that 969 (19.7%) isolates were sensitive to all four first-line drugs, 3941 (80.3%) isolates were resistant to one or more drugs, and 3041 (61.9%) isolates were resistant to both RIF and INH with or without resistance to any other drug (multidrug resistant). Monodrug resistance to SM and EMB was observed in 94 (1.9%) and 8 (0.16%) isolates, respectively. RIF resistance without INH resistance was observed in 22 (0.44%) isolates. There were 776 isolates sensitive to RIF, but resistant to INH. Among these, INH resistance with EMB and/or SM was observed in 367 (7.47%) isolates, whereas 409 (8.3%) isolates were resistant to INH alone. The results of line probe assay from 2012 to 2015 were also analyzed, and the resistance to INH alone among all isolates with valid results was found to be 9.32% (1462/15,676). More than 75% of these isolates harbor mutations in the kat G gene associated with high-level resistance.

CONCLUSION

INH resistance among RIF-susceptible isolates was present in 10-15% of the total cases. Among these cases, the use of RIF susceptibility alone will fail to detect INH resistance. Since higher rates of failure, relapse, or acquired resistance are linked with INH resistance, rollout of techniques focusing on RIF resistance must, therefore, be accompanied by strict monitoring for better management of patients.

Early detection of multi-drug resistance and common mutations in Mycobacterium tuberculosis isolates from Delhi using GenoType MTBDRplus assay

PURPOSE

There is scarcity of prevalence data of multi-drug-resistant tuberculosis (MDR-TB) data and common mutations responsible in North India. This study aimed to detect MDR-TB among MDR-TB suspects from Delhi and mutation patterns using GenoType MTBDRplus assay.

MATERIALS AND METHODS

All MDR suspects in five districts of New Delhi were referred to the laboratory from 1 st October 2011 to 31 st December 2012 as per criterion defined by Programmatic Management of Drug Resistant Tuberculosis (PMDT). GenoType MTBDRplus assay was performed on 2182 samples or cultures and mutations in the rpoB gene for rifampicin (RIF) and katG and inhA genes for isoniazid (INH) were analyzed.

RESULTS

A total of 366 (16.8%) MDR-TB cases were diagnosed. MDR rate was found to be 32%, 16.6% and 10.2% during criterion A, B and C respectively. The most common mutation detected for RIF was S531L (59.0%) and for INH was S315T1 (88.3%). Mutations S531L and S315T1 occurred significantly higher in MDR strains as compared to RIF mono-resistant and INH mono-resistant strains, respectively. Average laboratory turn-around time (TAT) for dispatch of result to districts for test conducted on samples was 4.4 days.

CONCLUSION

GenoType MTBDRplus is a useful assay for rapid detection of MDR-TB. The common mutations for RIF and INH were similar to those seen in other regions. However, mutations determining MDR strains and mono-resistant strains differed significantly for both RIF and INH.

Utility of MPT64 Antigen Detection for Rapid Confirmation of Mycobacterium tuberculosis Complex

Background:

Rapid differentiation of the Mycobacterium tuberculosis complex (MTBC) and mycobacteria other than tuberculosis (MOTT) is crucial to facilitate early and effective treatment of the patients. Clinical presentation of MTBC and MOTT is not always very clear and routine conventional methods are time consuming.

Materials and Methods:

In the present study, the MPT64 protein detection-based immunochomatographic test (SD Bioline Kit, Standard Diagnostics, Inc., Korea) was compared with the conventional biochemical method.

Results:

The sensitivity, specificity, positive predictive, and negative predictive values of the SD AgMPT64 kit were found to be 100, 96.4, 98.72, and 100%, respectively.

Conclusions:

Our results have demonstrated that the SD bioline kit is a rapid, reliable method and it can be used in the Revised National Tuberculosis Control Program (RNTCP) of India, for the appropriate management of tuberculosis.

Phylogenetic associations with drug-resistant Mycobacterium tuberculosis isolates in a paediatric population

SETTING

Department of Microbiology, National Institute of Tuberculosis and Respiratory Diseases, New Delhi, India.

OBJECTIVES

As paediatric tuberculosis (TB) is a surrogate marker for actively transmitted disease in a community, we investigated drug resistance patterns of 97 Mycobacterium tuberculosis complex strains isolated from children and explored their phylogenetic associations.

DESIGN

A total of 111 paediatric patients who attended the out-patient department during the study period 2009-2011 and whose sputum samples were sent to the Microbiology Department for liquid culture and drug susceptibility testing (DST) were included in this study. DST and spoligotyping were performed on cultures positive for M. tuberculosis complex.

RESULTS

DST against four first-line drugs showed that 31 of 97 (32%) strains were pan-susceptible, while 66/97 (68%) were resistant to at least one drug, including 55/97 (56.7%) that were resistant to at least isoniazid and rifampicin (i.e., multidrug-resistant). The majority of the isolates (n = 81/90, 90%) belonged to the principal genetic group 1 strains, the most predominant spoligotyping clusters being spoligotyping international type (SIT)1/Beijing (n = 28), SIT26/CAS1-Delhi (n = 27) and SIT53/T1 (n = 6).

CONCLUSION

The involvement of Beijing and CAS1-Delhi clades in paediatric TB patients suggests that these two lineages play a major role in ongoing active transmission.

Identification of mycobacterial species by PCR restriction enzyme analysis of thehsp65gene — an Indian experience

Nowadays, nontuberculous mycobacteria (NTM) often cause pulmonary and extrapulmonary disease. Species identification of NTM determines the line of treatment and management of the disease. The routine diagnostic methods, i.e., smear microscopy and biochemical identification, of nontuberculous mycobacteria are tedious and time consuming and not all laboratories can perform these tests on a routine basis. A PCR targeting the hsp65 gene was implemented using standard strains and was applied to 109 clinical isolates. The PCR-amplified product was subjected to restriction enzyme analysis using BstEII and HaeIII. The results obtained were compared with that of biochemical tests. Of 109 NTM, 107 were identified to species level. PCR plus restriction enzyme analysis (PRA) identified 12 types of NTM. Common species identified were Mycobacterium chelonae (32), a rapid growing NTM, and Mycobacterium avium complex (21), among the slow growing NTM. PRA and biochemical identification showed 95.32% (102/107) concordant results. PRA is fast, cheap, and accurate for identification of potentially pathogenic NTM.

Detection of multi-drug resistance & characterization of mutations in Mycobacterium tuberculosis isolates from North- Eastern States of India using GenoType MTBDRplus assay

BACKGROUND & OBJECTIVES

Information on drug resistance tuberculosis is sparse from North-East (N-E) States of India. We undertook this study to detect multi-drug resistant tuberculosis (MDR-TB) among MDR-TB suspects, and common mutations among MDR-TB cases using GenoType MTBDRplus.

METHODS

All MDR suspect patients deposited sputum samples to peripheral designated microscopy centres (DMC) in North-East States. The district TB officers (DTOs) facilitated the transport of samples collected during January 2012 to August 2012 to our laboratory. The line probe assay to detect common mutations in the rpoB gene for rifampicin (RIF) and katG and inhA genes for isoniazid (INH), respectively was performed on 339 samples or cultures.

RESULTS

A total of 553 sputum samples from MDR suspects were received of which, 181 (32.7%) isolates were found to be multi-drug resistant. Missing WT8 along with mutation in codon S531L was commonest pattern for rifampicin resistant isolates (65.1%) and missing WT along with mutations in codon S315T1 of katG gene was commonest pattern for isoniazid resistant isolates (86.2%). Average turn-around time for dispatch of LPA result to these States from cultures and samples was 23.4 and 5.2 days, respectively. INTERPRETATIONS & CONCLUSIONS: The MDR-TB among MDR-TB suspects in North-Eastern States of India was found to be 32.7 per cent. The common mutations obtained for RIF and INH in the region were mostly similar to those reported earlier.

Development of a POC test for TB based on multiple immunodominant epitopes of M. tuberculosis specific cell-wall proteins

The need for an accurate, rapid, simple and affordable point-of-care (POC) test for Tuberculosis (TB) that can be implemented in microscopy centers and other peripheral health-care settings in the TB-endemic countries remains unmet. This manuscript describes preliminary results of a new prototype rapid lateral flow TB test based on detection of antibodies to immunodominant epitopes (peptides) derived from carefully selected, highly immunogenic M. tuberculosis cell-wall proteins. Peptide selection was initially based on recognition by antibodies in sera from TB patients but not in PPD-/PPD+/BCG-vaccinated individuals from TB-endemic settings. The peptides were conjugated to BSA; the purified peptide-BSA conjugates striped onto nitrocellulose membrane and adsorbed onto colloidal gold particles to devise the prototype test, and evaluated for reactivity with sera from 3 PPD-, 29 PPD+, 15 PPD-unknown healthy subjects, 10 patients with non-TB lung disease and 124 smear-positive TB patients. The assay parameters were adjusted to determine positive/negative status within 15 minutes via visual or instrumented assessment. There was minimal or no reactivity of sera from non-TB subjects with the striped BSA-peptides demonstrating the lack of anti-peptide antibodies in subjects with latent TB and/or BCG vaccination. Sera from most TB patients demonstrated reactivity with one or more peptides. The sensitivity of antibody detection ranged from 28–85% with the 9 BSA-peptides. Three peptides were further evaluated with sera from 400 subjects, including additional PPD-/PPD+/PPD-unknown healthy contacts, close hospital contacts and household contacts of untreated TB patients, patients with non-TB lung disease, and HIV+TB- patients. Combination of the 3 peptides provided sensitivity and specificity>90%. While the final fully optimized lateral flow POC test for TB is under development, these preliminary results demonstrate that an antibody-detection based rapid POC lateral flow test based on select combinations of immunodominant M. tb-specific epitopes may potentially replace microscopy for TB diagnosis in TB-endemic settings.

Multi-drug resistant tuberculosis among category I treatment failures--a retrospective study

BACKGROUND

Tuberculosis (TB) remains a major global health problem and ranks as the second leading cause of death worldwide. An important cause of TB epidemic is the emergence of multi drug resistant (MDR) strains of Mycobacterium tuberculosis. Despite the availability of treatment that is expected to cure most cases of TB, levels of MDR-TB remain worryingly high in India.

OBJECTIVE

This study was carried out to ascertain the prevalence of MDR-TB among category I pulmonary TB treatment failure patients.

METHODS

This was a retrospective study involving 750 pulmonary tuberculosis patients enrolled at six district centres of Delhi State under RNTCP who failed to respond to CAT I treatment and whose sputum samples were submitted for culture and drug sensitivity testing (DST) over a period of three years (2009-2012). MDR-TB was defined as TB caused by bacilli showing resistance to at least isoniazid and rifampicin.

RESULTS

Out of the total 750 patients included in the study, 470 (62.6 %) were culture positive. Of these, 377 (80.2%) were subjected to DST and rest 93 (19.7%) were excluded. Ultimately, DST result was available for 353 (93.6 %) cases. 239 (68%) cases were detected as multi drug resistant TB.

CONCLUSION

High proportion of MDR-TB (68%) among culture positive CAT I treatment failure cases highlights the need for rapid diagnostic tests which will enable the detection of MDR-TB at an early stage and will thus minimize the risk of transmission as well as the possible errors associated with the treatment.

Rapid identification of clinical mycobacterial isolates by protein profiling using matrix assisted laser desorption ionization-time of flight mass spectrometry

PURPOSE

The purpose of this study was to evaluate the identification of Mycobacterium tuberculosis which is often plagued with ambiguity. It is a time consuming process requiring 4-8 weeks after culture positivity, thereby delaying therapeutic intervention. For a successful treatment and disease management, timely diagnosis is imperative. We evaluated a rapid, proteomic based technique for identification of clinical mycobacterial isolates by protein profiling using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

MATERIALS AND METHODS

Freshly grown mycobacterial isolates were used. Acetonitrile/trifluoroacetic acid extraction procedure was carried out, following which cinnamic acid charged plates were subjected to identification by MALDI-TOF MS.

RESULTS

A comparative analysis of 42 clinical mycobacterial isolates using the MALDI-TOF MS and conventional techniques was carried out. Among these, 97.61% were found to corroborate with the standard methods at genus level and 85.36% were accurate till the species level. One out of 42 was not in accord with the conventional assays because MALDI-TOF MS established it as Mycobacterium tuberculosis (log (score)>2.0) and conventional methods established it to be non-tuberculous Mycobacterium.

CONCLUSIONS

MALDI-TOF MS was found to be an accurate, rapid, cost effective and robust system for identification of mycobacterial species. This innovative approach holds promise for early therapeutic intervention leading to better patient care.

Sputum smear positivity at two months in previously untreated pulmonary tuberculosis patients

BACKGROUND AND OBJECTIVES

In pulmonary tuberculosis, bacteriological status at two months affects subsequent treatment and prognosis. The effect on treatment outcome and risk factors for sputum conversion at two months treatment in previously untreated pulmonary tuberculosis (PTB) patients was studied in the following report.

METHODS

A 1:1 case-control study was performed from June 2006 to February 2008 on patients in the Revised National Tuberculosis Control Program in a tertiary level institute in Delhi, India. Patients with previously untreated PTB with sputum smear positive at 2months of treatment (cases) were compared with those who achieved conversion (controls).

RESULTS

In 74 cases and 74 controls, independent risk factors for sputum smear positive at two months were: illness for >2months, presence of cavity or extensive disease on chest X-ray, and interruption in intensive phase of treatment. Patients with smear positive at 2 or 3months of treatment were more likely to fail or default from treatment. Aforesaid factors were also associated with sputum culture positive status at 2months in univariate analysis. Patients who interrupted treatment ⩾3 times in the first two months were more likely to be culture positive at two months and had a higher rate of default and failure.

CONCLUSIONS

Illness for more than 2months, presence of cavity or extensive disease on chest X-ray, and interruption in intensive phase of treatment are independent risk factors for sputum smear positivity at two months, which in turn is associated with poor treatment outcomes. Patients with these factors merit special attention under the national program.

Predominance of Beijing genotype in extensively drug resistant Mycobacterium tuberculosis isolates from a tertiary care hospital in New Delhi, India

Out of a total of 311 Mycobacterium tuberculosis isolates from sputum specimens subjected to first- and second-line drug-susceptibility testing (DST) at a hospital serving as a referral center for chronic tuberculosis (TB) cases in New Delhi, 232/311 (74.6%) isolates were found to be resistant to isoniazid and rifampicin. Among multidrug-resistant (MDR) isolates, 119/232 (51.3%) were resistant to four first-line drugs (streptomycin, isoniazid, rifampicin and ethambutol). Mono-resistance to isoniazid was observed in 18 (5.7%) isolates, while none of the isolates tested showed mono-resistance to rifampicin. 50/232 (21.5%) isolates met the definition of extensively drug resistant (XDR) TB, i.e., additional resistance to a fluoroquinolone and at least one of the three injectable second-line drugs: kanamycin, capreomycin, or amikacin. Spoligotyping of the XDR-TB isolates revealed 14 patterns; 39/50 (78%) isolates being grouped in three clusters vs. 11/50 (22%) isolates being unique. SIT1/Beijing represented the largest cluster (n=21, 42%), followed by SIT26/CAS1-Delhi (n=10, 20%) and SIT 53/T1 (n=8 isolates; 16%). This study corroborates recent observations from North India suggesting that both Beijing and CAS1-Delhi lineages constitute the bulk of XDR-TB isolates that are disseminating rapidly across a large geographical region in and around the capital city of India.

Fate of sputum samples transported in bottles containing cetylpyridinium chloride and sodium chloride: a national reference laboratory study

The transportation of sputum samples may sometimes take more than one week which results in an increased contamination rate and loss of positive cultures. The current study was planned to analyze the recovery rate of mycobacteria from transported samples with and without Cetylpyridinium chloride (CPC). Addition of CPC is useful for isolation of M. tuberculosis from sputum subjected to long-term storage.

A pilot study of same day sputum smear examination, its feasibility and usefulness in diagnosis of pulmonary TB

INTRODUCTION

A large number of tuberculosis cases are continuously being reported from India and other developing countries leading to high morbidity and mortality. In spite of many newer tests available for diagnosing a case of tuberculosis, smear microscopy of sputum is still the preferred test under programmatic conditions. The current national and international guidelines recommend two sputum smear examinations in two days for diagnosing cases of tuberculosis, which is time-consuming, tedious, needs multiple visits, leading to high dropout of infectious cases. In the background of existing limitations of smear microscopy, we attempted to complete the diagnosis of tuberculosis on same day by serial collection of the spot sputum specimen and analyze its advantages, feasibility and viability.

MATERIAL & METHODS

The study was undertaken by the Department of Microbiology, Lala Ram Sarup Institute of Tuberculosis and Respiratory Diseases during May 2010 to April 2011. Sputum specimens were collected from 330 randomly selected tuberculosis suspects who attended OPD of hospital, patients submitted spot and home collected morning sputum sample in a standard method and spot and additional spot sputum (X- spot) collected one hour after the first spot sample as per the proposed front loading method. All the samples received were stained by acid fast Ziehl-Neelsen (ZN) stain and examined on the same day. The sputum sample was pooled and cultured in Lowenstein Jensen (LJ) media in duplicate set of bottles. The results of two different microscopic methods were compared with the gold standard culture test.

RESULTS

Out of the total 330 TB suspects, 70.60% were males and 29.39% females. The most common complaint was of cough with sputum (88.18%), chest pain (70.21%), fever (55.15%) and loss of appetite (43.03%). Upon examining the total sputum slides, 18.48 % were positive for acid fast bacilli. The smear positivity was 61/330 (18.48%) by standard methods and in proposed new method 43/330 (13.03%). Sensitivity of the standard and proposed new method smear microscopy was 58.25% and 40.07% respectively and specificity was 99.55% in both the methods.

CONCLUSION

Same day smear microscopy for diagnosing tuberculosis by a proposed new method of smear examination in the case of suspected tuberculosis seems not a promising step towards improving the quality of sputum smear examination. The results of sensitivity and specificity of the two approaches were not similar. More than eighty per cent responded in favour of same day sputum delivery system and getting result on same day. This study can be confirmed on larger scale and preference of patients can be examined in peripheral laboratory also before taking it up for consideration in the national tuberculosis programme.

Prevalence of XDR TB cases--a retrospective study from a tertiary care TB hospital

BACKGROUND

The emergence of XDR -TB strains is a major roadblock in the successful implementation of TB control programmes. This further leads to high morbidity and mortality, especially in immuno-compromised patients. Identification and observation of resistance patterns of XDR-TB strains may help clinicians manage MDR-TB cases, the treatment line of which is expensive, time-taking and involves intake of toxic drugs with many side-effects. Our study is aimed to find out the prevalence of XDR-TB among the MDR-TB strains isolated in a tertiary care hospital.

MATERIAL & METHODS

The study population consisted of 223 patients of tuberculosis who were culture positive and Mycobacterium tuberculosis was resistant to Rifampicin and Isoniazid during January 2007 to December 2009. Each patient had submitted two sputum samples i.e. spot and morning. The identified Mycobacterium tuberculosis complex was subjected to drug sensitivity testing by first and second line drugs by proportion and absolute concentration methods as per standard procedure.

RESULTS

The results showed that 20.17% strains (45/223) were XDR-TB strains. Most of these strains showed resistance to four drug combination viz. KM, ETH, OFX & PAS (5.82%), KM & OFX (3.13%), OFX, KM and ETH (1.79%), 1.34% strains showed resistance to all the drugs i.e. pan resistance and other combinations in the remaining strains. Nearly 80% of the XDR-TB strains showed resistance to three or more drugs combination pattern.

CONCLUSION

The multidrug resistant TB cases need urgent and timely sensitivity report for second line ATT drugs to help clinicians start proper drug combinations to treat MDR-TB patients.

A thyroid tubercular abscess and bilateral symmetrical hilar lymphadenopathy: a rare association

An 18-year-old boy presented with a rare association of a thyroid tubercular abscess and bilateral symmetrical hilar lymphadenopathy. He was put on a Category I regimen with standard short course daily chemotherapy of four anti-tubercular drugs under the National Tuberculosis Programme. After a six-month of anti-tubercular treatment (ATT), the boy showed clinical and bacteriological improvement. The thyroid scan with Technetium 99 (Tc 99) and the chest skiagram also became normal.

Polymerase chain reaction--based sequence-specific oligonucleotide hybridization analysis of HLA class II antigens in pulmonary tuberculosis: relevance to chemotherapy and disease severity

HLA antigens were studied by serology and polymerase chain reaction-based sequence-specific oligonucleotide hybridization techniques in 153 patients with pulmonary tuberculosis (PTB) and 289 healthy controls. HLA-DR2 was present more frequently in PTB patients than in controls (51% vs. 36.3%; corrected P[Pc]=.029, relative risk [RR] = 1.8). The DR2 association was stronger in patients in the drug-failure group (n=56; Pc=.000012, RR=3.7) than in healthy controls and in patients in the drug-responder group. No significant deviation was observed in HLA allelic frequencies in various patient groups, as determined by radiographs of lung lesions. Molecular subtyping of DR2 revealed that the bulk of the allele was DRB1*1501 and DRB1*1502 in patients and controls. There was no skewing of the frequency of these molecular subtypes of DR2 in patients, suggesting that the whole DR2 molecule or its closely linked gene(s) may be involved in governing patient susceptibility to PTB and, particularly, development of the severe drug-resistant form of the disease.