Diagnosis of tuberculosis: the experience at a specialized diagnostic laboratory

Mashta, Anita; Mishra, Pooja; Philipose, Sonia; Tamilzhalagan, Sembulingam; Hanif, Mahmud; Bhaskar, Sangeeta; Upadhyay, Pramod

doi:10.1186/1477-5751-10-16

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…We did not perform a similar sub-analysis for the MODS because the publications were inadequate for the analysis. Instead, we performed a sub-group analysis, excluding the outlier study which had reported what the authors decsribed as “ unexplained observed disturbing inconsistencies in results”, when they used the MODS for diagnosis of smear-negative TB [ 40 ]. Pooled sensitivity of MODS increased from 73% to 82%, and specificity increased from 91% to 95%.…”

Section: Resultsmentioning

confidence: 99%

Meta-analysis to compare the accuracy of GeneXpert, MODS and the WHO 2007 algorithm for diagnosis of smear-negative pulmonary tuberculosis

et al. 2013

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BackgroundSmear-negative pulmonary tuberculosis (SN-PTB), which is common in HIV-infected patients, is difficult to diagnose using smear microscopy alone. In 2007, the WHO developed an algorithm to improve the diagnosis and management of smear-negative tuberculosis in HIV prevalent and resource constrained settings. Implementation of the algorithm required individuals with presumptive TB to be initially evaluated using two sputum microscopy examinations followed by clinical diagnosis that may include chest X-ray and antibiotic treatment in smear-negative individuals. Since that time, the WHO has endorsed several new tests for diagnosis of tuberculosis. However, it is unclear how the new tests perform when compared to the WHO 2007 algorithm in diagnosis of SN-PTB. Using meta-analysis study design, we summarized and compared the accuracy of Xpert® MTB/Rif assay (GeneXpert) and Microscopic Observation Drug Susceptibility assay (MODS), with the WHO 2007 algorithm in the diagnosis of SN-PTB.MethodsA systematic review and meta-analysis of publications on GeneXpert, or MODS, or the WHO 2007 algorithm for diagnosis of SN-PTB, using culture as reference test was performed. Meta-Disc software was used to obtain pooled sensitivity and specificity of the diagnostic methods. Heterogeneity in the accuracy estimates was tested by reviewing the generated forest plots, sROC curves and the Spearman correlation coefficient of the logit of true positive rate versus the logit of false positive rate.ResultsTwenty-four publications on all three diagnostic methods were meta-analyzed. The pooled sensitivity and specificity for detection of smear-negative pulmonary tuberculosis were 67% and 98% for GeneXpert, 73% and 91% for MODS, and 61% and 69% for WHO 2007 algorithm, respectively. The sensitivity of GeneXpert reduced from 67% to 54% when sub-group analysis of studies with patient HIV prevalence ≥30% was performed.ConclusionThe GeneXpert, MODS, and the WHO algorithm have moderate to high accuracy for the diagnosis of SN-PTB. However, the accuracy of the tests is extremely variable. The setting and context under which the tests are conducted in addition to several other factors could explain this variability. There is therefore need to investigate these factors further. The information from these studies would inform the adoption and placement of these new tests.

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Section: Resultsmentioning

confidence: 99%

Meta-analysis to compare the accuracy of GeneXpert, MODS and the WHO 2007 algorithm for diagnosis of smear-negative pulmonary tuberculosis

et al. 2013

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“…The reason given was perhaps there is flawed generalization that all pathogenic MTB form cords. [ 11 ]…”

Section: Discussionmentioning

confidence: 99%

Concurrent evaluation of microscopic observation of drug susceptibility assay for pulmonary and extrapulmonary tuberculosis

Zadbuke

Set²,

Khan³

et al. 2017

J Lab Physicians

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BACKGROUND:Methods for detection and drug susceptibility of tuberculosis (TB) with solid media are inexpensive but slow and laborious. Rapid methods to diagnose TB and multidrug-resistant TB (MDR-TB) are a global priority for TB control.OBJECTIVES:A study was performed to compare the sensitivity of detection of mycobacterial growth and time of culture positivity by microscopic observation of drug susceptibility (MODS) assay with that of Lowenstein–Jensen (LJ) culture in pulmonary and extrapulmonary TB and to evaluate the concordance of the susceptibilities to isoniazid (INH) and rifampicin (RIF) by MODS and proportion method on LJ.MATERIALS AND METHODS:A prospective, laboratory-based study was conducted on a total of 300 samples from suspected cases of pulmonary and extrapulmonary TB. Samples were inoculated on LJ medium as per the standard guidelines and MODS assay was performed.RESULTS:Sensitivity of MODS assay was 80% and 83.3% and specificity was 92.9% and 83.3% for pulmonary and extrapulmonary samples, respectively. Difference between mean time to detection of Mycobacterium TB (MTB) by LJ medium and MODS was statistically significant, with MODS being faster. drug susceptibility testing (DST) by MODS when compared to economic variant of proportion method was 87.87% for RIF, 90.9% for INH, and 96.96% for MDR-TB detection.CONCLUSION:MODS assay provides rapid, safe, and sensitive detection of TB faster than the existing gold standard. It is extremely promising in effectively diagnosing MDR-TB.

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Evaluation of the Xpert® MTB/Rif test, microscopic observation drug susceptibility test and nitrate reductase assay, for rapid and accurate diagnosis of smear-negative tuberculosis in HIV patients

Walusimbi¹,

Bwanga²,

Costa³

et al. 2013

International Journal of Mycobacteriology

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Diagnosis of smear-negative tuberculosis (TB), which is frequently seen in HIV-infected patients, is a challenge without conventional culture methods. Since 2007, the WHO (World Health Organization) has endorsed new or improved tests for increased and rapid diagnosis of TB. This study was undertaken in an effort to evaluate the accuracy of two rapid culture methods: the Microscopic Observation Drug Susceptibility assay (MODS) and Nitrate Reductase Assay (NRA), and the molecular based test Xpert® MTB/Rif (Xpert), for diagnosis of smear-negative TB in HIV patients using the mycobacteria growth indicator tube (MGIT) in the BACTEC(TM) MGIT(TM) 960 system as the reference test. 430 smear-negative patients with presumptive TB were enrolled in a cross-sectional study at a tertiary care facility in Uganda. Their sputum was tested on MODS, NRA, Xpert and MGIT. Of the 430 patients, 373 had complete results to compute test accuracy. Mycobacterium tuberculosis (MTB) was detected in 43 patients by MGIT. The sensitivity and specificity were 24.4% and 98.1% for MODS, 41.5% and 92% for NRA, 48.8% and 95.1% for Xpert, respectively. The low sensitivity of the tests implies that additional diagnostics such as chest X-ray and conventional liquid culture methods might still be needed to detect TB in smear-negative HIV patients. The high specificity of the tests is useful to confirm TB in HIV patients with symptoms suggestive of TB.

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Diagnosis of tuberculosis: the experience at a specialized diagnostic laboratory

Cited by 5 publications

References 21 publications

Meta-analysis to compare the accuracy of GeneXpert, MODS and the WHO 2007 algorithm for diagnosis of smear-negative pulmonary tuberculosis

Meta-analysis to compare the accuracy of GeneXpert, MODS and the WHO 2007 algorithm for diagnosis of smear-negative pulmonary tuberculosis

Concurrent evaluation of microscopic observation of drug susceptibility assay for pulmonary and extrapulmonary tuberculosis

Evaluation of the Xpert® MTB/Rif test, microscopic observation drug susceptibility test and nitrate reductase assay, for rapid and accurate diagnosis of smear-negative tuberculosis in HIV patients

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