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Diagnostic accuracy of microscopic Observation Drug Susceptibility (MODS) assay for pediatric tuberculosis in Hanoi, Vietnam.

ABSTRACT: Microscopic [corrected] Observation Drug Susceptibility (MODS) has been shown to be an effective and rapid technique for early diagnosis of tuberculosis (TB). Thus far only a limited number of studies evaluating MODS have been performed in children and in extra-pulmonary tuberculosis. This study aims to assess relative accuracy and time to positive culture of MODS for TB diagnosis in children admitted to a general pediatric hospital in Vietnam.Specimens from children with suspected TB were tested by smear, MODS and Lowenstein-Jensen agar (LJ). 1129 samples from 705 children were analyzed, including sputum (n=59), gastric aspirate (n=775), CSF (n=148), pleural fluid (n=33), BAL (n=41), tracheal fluid (n=45), other (n=28). 113 TB cases were defined based on the "clinical diagnosis" (confirmed and probable groups) as the reference standard, in which 26% (n=30) were diagnosed as extra-pulmonary TB. Analysis by patient shows that the overall sensitivity and specificity of smear, LJ and MODS against "clinical diagnosis" was 8.8% and 100%, 38.9% and 100%, 46% and 99.5% respectively with MODS significantly more sensitive than LJ culture (P=0.02). When analyzed by sample type, the sensitivity of MODS was significantly higher than LJ for gastric aspirates (P=0.004). The time to detection was also significantly shorter for MODS than LJ (7 days versus 32 days, P<0.001).MODS [corrected] is a sensitive and rapid culture technique for detecting TB in children. As MODS culture can be performed at a BSL2 facility and is inexpensive, it can therefore be recommended as a routine test for children with symptoms suggestive of TB in resource-limited settings.

SUBMITTER: Tran ST

PROVIDER: S-EPMC3762843 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Diagnostic accuracy of microscopic Observation Drug Susceptibility (MODS) assay for pediatric tuberculosis in Hanoi, Vietnam.

Tran Sinh Thi ST Renschler John Patrick JP Le Hai Thanh HT Dang Hang Thi Thu HT Dao Tuan Minh TM Pham An Nhat AN Nguyen Liem Thanh LT Van Nguyen Hung H Thi Thu Nguyen Thuy T Ngoc Le Sy S Fox Annette A Caws Maxine M Thi Quynh Nguyen Nhu N Horby Peter P Wertheim Heiman H

PloS one 20130904 9

<h4>Introduction</h4>Microscopic [corrected] Observation Drug Susceptibility (MODS) has been shown to be an effective and rapid technique for early diagnosis of tuberculosis (TB). Thus far only a limited number of studies evaluating MODS have been performed in children and in extra-pulmonary tuberculosis. This study aims to assess relative accuracy and time to positive culture of MODS for TB diagnosis in children admitted to a general pediatric hospital in Vietnam.<h4>Methods/principal findings< ...[more]

PMID: 24023726

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Project description:New diagnostic tools are urgently needed to interrupt the transmission of tuberculosis and multidrug-resistant tuberculosis. Rapid, sensitive detection of tuberculosis and multidrug-resistant tuberculosis in sputum has been demonstrated in proof-of-principle studies of the microscopic-observation drug-susceptibility (MODS) assay, in which broth cultures are examined microscopically to detect characteristic growth.In an operational setting in Peru, we investigated the performance of the MODS assay for culture and drug-susceptibility testing in three target groups: unselected patients with suspected tuberculosis, prescreened patients at high risk for tuberculosis or multidrug-resistant tuberculosis, and unselected hospitalized patients infected with the human immunodeficiency virus. We compared the MODS assay head-to-head with two reference methods: automated mycobacterial culture and culture on Löwenstein-Jensen medium with the proportion method.Of 3760 sputum samples, 401 (10.7%) yielded cultures positive for Mycobacterium tuberculosis. Sensitivity of detection was 97.8% for MODS culture, 89.0% for automated mycobacterial culture, and 84.0% for Löwenstein-Jensen culture (P<0.001); the median time to culture positivity was 7 days, 13 days, and 26 days, respectively (P<0.001), and the median time to the results of susceptibility tests was 7 days, 22 days, and 68 days, respectively. The incremental benefit of a second MODS culture was minimal, particularly in patients at high risk for tuberculosis or multidrug-resistant tuberculosis. Agreement between MODS and the reference standard for susceptibility was 100% for rifampin, 97% for isoniazid, 99% for rifampin and isoniazid (combined results for multidrug resistance), 95% for ethambutol, and 92% for streptomycin (kappa values, 1.0, 0.89, 0.93, 0.71, and 0.72, respectively).A single MODS culture of a sputum sample offers more rapid and sensitive detection of tuberculosis and multidrug-resistant tuberculosis than the existing gold-standard methods used.

Project description:BackgroundNewly diagnosed patients without anti-tuberculosis (TB) treatment histories have not often undergone drug susceptibility testing (DST), but have received the standard treatment regimen without information about their DST profiles in many countries with inadequate resources.MethodsWe collected 346 clinical isolates from previously untreated patients with smear-positive active TB in Hanoi, the capital of Vietnam. Of these, 339 were tested for susceptibility to four first-line anti-TB drugs, including isoniazid (INH), rifampicin (RMP), streptomycin (SM), and ethambutol (EMB), using the proportion method. A pyrazinamidase (PZase) test was used to assess pyrazinamide (PZA) resistance. Results of the culture-based drug susceptibility tests were confirmed by those from reverse hybridization-based line probe assays (LiPAs) that detected mutations associated with RMP, INH, PZA, and fluoroquinolone (FQ) resistance. To investigate a diversity of these strains, IS6110-probed restriction fragment length polymorphisms (RFLPs) were analyzed. Nucleotide sequences for furA-katG and fabG1-inhA operons, transcription units responsible for INH resistance, were also determined.ResultsOf the isolates tested, 127 (37.5%) were resistant to at least one of the four drugs, which included 93 (27.4%) isolates that were resistant to INH. RFLP analysis identified four clusters defined by similarity of the band patterns, which accounted for 46.1% of the tested isolates. Among the clustered isolates, 37.7% were resistant to INH, most of which (85.4%) carried a g944c mutation, which causes an S315T amino acid substitution, in the katG gene.ConclusionsOur results suggest that drug-resistant strains, particularly those with INH resistance characterized by a single mutation, S315T, are spreading in Hanoi, Vietnam. When RMP resistance is combined with this setting, patients are not easily cured by conventional short-term treatment. We will need to carefully monitor these trends and search for the origins and transmission routes of these strains.

Dataset Information

Diagnostic accuracy of microscopic Observation Drug Susceptibility (MODS) assay for pediatric tuberculosis in Hanoi, Vietnam.

Publications

Diagnostic accuracy of microscopic Observation Drug Susceptibility (MODS) assay for pediatric tuberculosis in Hanoi, Vietnam.

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