Setting

Tuberculosis (TB) hospital in Mumbai, India.

Objective

To describe the mobility patterns of persons with suspected drug-resistant tuberculosis (DR-TB) and to assess whether there were significant differences in demographic or risk characteristics based on mobility.

Design

Observational cohort study of TB clinic patients at risk for DR-TB.

Results

Among 602 participants, 37% had ever moved from their place of birth; 14% were local movers (within state), and 23% were distant movers, between states or countries. Univariate multinomial logistic regression models showed that distant movers were more likely than non-movers to have lower income, less education, a greater number of previous TB episodes, and to have ever smoked. Compared to non-movers, local movers were more likely to have lower income and were more likely to have seen a doctor in the past 2 years. Clinical outcomes, including DR-TB, diabetes, and human immunodeficiency virus (HIV), did not differ between the three mobility groups.

Conclusion

Mobility was common among patients at risk for DR-TB in Mumbai. TB programs should consider the implications of mobility on the protracted treatment for DR-TB in India.

Pyrazinamide (PZA) is an important first-line drug in all existing and new tuberculosis (TB) treatment regimens. PZA-resistance in M. tuberculosis is increasing, especially among M/XDR cases. Noted issues with PZA Drug Susceptibility Testing (DST) have driven the search for alternative tests. This study provides a comprehensive assessment of PZA molecular diagnostics in M/XDR TB cases. A set of 296, mostly XDR, clinical M. tuberculosis isolates from four countries were subjected to DST for eight drugs, confirmatory Wayne's assay, and whole-genome sequencing. Three genes implicated in PZA resistance, pncA, rpsA, and panD were investigated. Assuming all non-synonymous mutations cause resistance, we report 90% sensitivity and 65% specificity for a pncA-based molecular test. The addition of rpsA and panD potentially provides 2% increase in sensitivity. Molecular heterogeneity in pncA was associated with resistance and should be evaluated as a diagnostic tool. Mutations near the N-terminus and C-terminus of PZase were associated with East-Asian and Euro-American lineages, respectively. Finally, Euro-American isolates are most likely to have a wild-type PZase and escape molecular detection. Overall, the 8-10% resistance without markers may point to alternative mechanisms of resistance. Confirmatory mutagenesis may improve the disconcertingly low specificity but reduce sensitivity since not all mutations may cause resistance.

BACKGROUND: Xpert^® MTB/RIF, a rapid, molecular TB diagnostic assay, can detect Mycobacterium tuberculosis and rifampin resistance directly from clinical sputum samples in <2 h with high sensitivity and specificity. The added diagnostic value of Xpert over smear microscopy at a national level in Myanmar has not been previously reported.METHODS: We evaluated 339,358 Xpert and demographic records captured from January 2015 to December 2018 as part of the Myanmar National TB Program Data Utilization and Connectivity Project to examine the additional diagnostic yield of Xpert relative to smear for the detection of M. tuberculosis for TB diagnosis in Myanmar, with a focus on people living with HIV (PLHIV) and sample type.RESULTS: Use of Xpert increased TB case detection by 40% compared to smear microscopy results. Among PLHIV, use of Xpert increased TB case detection by almost 100% compared to smear microscopy results.CONCLUSION: Xpert testing identified more patients with TB than smear microscopy alone, particularly in cohorts with significant proportions of PLHIV. The use of Xpert as a screening tool in countries with a high burden of TB could lead to significantly increased diagnosis of TB at a regional and national level.

Molecular diagnostic assays, with their ability to rapidly detect resistance-associated mutations in bacterial genes, are promising technologies to control the spread of drug-resistant tuberculosis (DR-TB). Sequencing assays provide detailed information for specific gene regions and can help diagnostic assay developers prioritize mutations for inclusion in their assays. We performed pyrosequencing of seven Mycobacterium tuberculosis gene regions (katG, inhA, ahpC, rpoB, gyrA, rrs, and eis) for 1,128 clinical specimens from India, Moldova, and South Africa. We determined the frequencies of each mutation among drug-resistant and -susceptible specimens based on phenotypic drug susceptibility testing results and examined mutation distributions by country. The most common mutation among isoniazid-resistant (INH(r)) specimens was the katG 315ACC mutation (87%). However, in the Eastern Cape, INH(r) specimens had a lower frequency of katG mutations (44%) and higher frequencies of inhA (47%) and ahpC (10%) promoter mutations. The most common mutation among rifampin-resistant (RIF(r)) specimens was the rpoB 531TTG mutation (80%). The mutation was common in RIF(r) specimens in Mumbai (83%) and Moldova (84%) but not the Eastern Cape (17%), where the 516GTC mutation appeared more frequently (57%). The most common mutation among fluoroquinolone-resistant specimens was the gyrA 94GGC mutation (44%). The rrs 1401G mutation was found in 84%, 84%, and 50% of amikacin-resistant, capreomycin-resistant, and kanamycin (KAN)-resistant (KAN(r)) specimens, respectively. The eis promoter mutation -12T was found in 26% of KAN(r) and 4% of KAN-susceptible (KAN(s)) specimens. Inclusion of the ahpC and eis promoter gene regions was critical for optimal test sensitivity for the detection of INH resistance in the Eastern Cape and KAN resistance in Moldova. (This study has been registered at ClinicalTrials.gov under registration number NCT02170441.).

Objective

To evaluate the performance of a recently updated rapid molecular diagnostic test, GenoType® MTBDRplus version 2, designed to detect drug resistance in both acid-fast bacilli (AFB) smear-negative and -positive specimens.

Design

Sputum samples from 1128 patients at risk for multidrug-resistant tuberculosis (MDR-TB) were tested using MTBDRplus v2 and compared with reference standard MGIT™ 960™ drug susceptibility testing. The relationship of participant human immunodeficiency virus (HIV) status, diabetic status, previous treatment, and smear gradation to the likelihood of obtaining an interpretable result was assessed using logistic regression.

Results

The sensitivity and specificity of MTBDRplus v2 for detecting MDR-TB, when compared to a reference standard, were respectively 96.0% (95%CI 93.5-97.6) and 99.2% (95%CI 97.0-99.9) in AFB smear-positive specimens and 82.8% (95%CI 63.5-93.5) and 98.3% (95%CI 89.9-99.9) in AFB smear-negative specimens. A dose-response relationship was observed between the proportion of interpretable test results and AFB smear bacterial load after adjusting for age, sex, body mass index, HIV status, previous treatment and diabetic status.

Conclusion

While MTBDRplus v2 performs well among both AFB smear-positive and -negative specimens, smear gradation appears to influence both the probability of obtaining an interpretable result and test sensitivity, indicating a significant association between bacillary load and test performance.

Background

Although directly observed therapy (DOT) is recommended worldwide for monitoring anti-tuberculosis treatment, transportation and personnel requirements limit its use.

Objective

To evaluate the feasibility and acceptability of 'video DOT' (VDOT), which allows patients to record and transmit medication ingestion via videos watched remotely by health care providers to document adherence.

Methods

We conducted a single-arm trial among tuberculosis (TB) patients in San Diego, California, USA, (n = 43) and Tijuana, Mexico (n = 9) to represent high- and low-resource settings. Pre-/post-treatment interviews assessed participant characteristics and experiences. Adherence was defined as the proportion of observed doses to expected doses.

Results

The mean age was 37 years (range 18-86), 50% were male, and 88% were non-Caucasian. The mean duration of VDOT use was 5.5 months (range 1-11). Adherence was similar in San Diego (93%) and Tijuana (96%). Compared to time on in-person DOT, 92% preferred VDOT, 81% thought VDOT was more confidential, 89% never/rarely had problems recording videos, and 100% would recommend VDOT to others. Seven (13%) participants were returned to in-person DOT and six (12%) additional participants had their phones lost, broken or stolen.

Conclusions

VDOT was feasible and acceptable, with high adherence in both high- and low-resource settings. Efficacy and cost-effectiveness studies are needed.

Objective

To develop and evaluate rapid, molecular-based drug susceptibility testing (DST) for extensively drug-resistant tuberculosis (XDR-TB), we assembled a phenotypically and genotypically diverse collection of Mycobacterium tuberculosis isolates from patients evaluated for drug resistance in four high-burden countries.

Methods

M. tuberculosis isolates from India (n = 111), Moldova (n = 90), the Philippines (n = 96), and South Africa (n = 103) were selected from existing regional and national repositories to maximize phenotypic diversity for resistance to isoniazid, rifampin (RMP), moxifloxacin, ofloxacin, amikacin, kanamycin, and capreomycin. MGIT™ 960 was performed on viable isolates in one laboratory using standardized procedures and drug concentrations. Genetic diversity within drug resistance phenotypes was assessed.

Results

Nineteen distinct phenotypes were observed among 400 isolates with complete DST results. Diversity was greatest in the Philippines (14 phenotypes), and least in South Africa (9 phenotypes). Nearly all phenotypes included multiple genotypes. All sites provided isolates resistant to injectables but susceptible to fluoroquinolones. Many patients were taking drugs to which their disease was resistant.

Discussion

Diverse phenotypes for XDR-TB-defining drugs, including resistance to fluoroquinolones and/or injectable drugs in RMP-susceptible isolates, indicate that RMP susceptibility does not ensure effectiveness of a standard four-drug regimen. Rapid, low-cost DST assays for first- and second-line drugs are thus needed.

Objective

To establish breakpoint concentrations for the fluoroquinolones (moxifloxacin [MFX] and ofloxacin [OFX]) and injectable second-line drugs (amikacin [AMK], kanamycin [KM] and capreomycin [CPM]) using the microscopic observation drug susceptibility (MODS) assay.

Setting

A multinational study conducted between February 2011 and August 2012 in Peru, India, Moldova and South Africa.

Design

In the first phase, breakpoints for the fluoroquinolones and injectable second-line drugs (n = 58) were determined. In the second phase, MODS second-line drug susceptibility testing (DST) as an indirect test was compared to MGIT™ DST (n = 89). In the third (n = 30) and fourth (n = 156) phases, we determined the reproducibility and concordance of MODS second-line DST directly from sputum.

Results

Breakpoints for MFX (0.5 μg/ml), OFX (1 μg/ml), AMK (2 μg/ml), KM (5 μg/ml) and CPM (2.5 μg/ml) were determined. In all phases, MODS results were highly concordant with MGIT DST. The few discrepancies suggest that the MODS breakpoint concentrations for some drugs may be too low.

Conclusion

MODS second-line DST yielded comparable results to MGIT second-line DST, and is thus a promising alternative. Further studies are needed to confirm the accuracy of the drug breakpoints and the reliability of MODS second-line DST as a direct test.