Household-contact investigation plus standard passive case finding was more effective than standard passive case finding alone for the detection of tuberculosis in a high-prevalence setting at 2 years. (Funded by the Australian National Health and Medical Research Council; ACT2 Australian New Zealand Clinical Trials Registry number, ACTRN12610000600044 .).

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BackgroundClose contacts of patients with tuberculosis (TB) have a substantial risk of developing the disease, particularly during the first year after exposure. Household contact investigation has recently been recommended as a strategy to enhance case detection in high-burden countries. However the barriers to its implementation in these settings remain poorly understood.MethodsA nested case–control study was conducted in Vietnam within the context of a large cluster randomised controlled trial of active screening for TB in household contacts of patients with pulmonary TB. The study population comprised contacts (and their index patients) from 12 Districts in six provinces throughout the country. Cases were contacts (and their index patients) that did not attend the scheduled screening appointment. Controls were those who did attend. We assessed relevant knowledge, attitudes and practices in cases and controls.ResultsThe acceptability of contact investigation was high among both cases (n = 109) and controls (n = 194). Both cases (47%) and controls (36%) commonly reported discrimination against people with TB. Cases were less likely than controls to understand that sharing sleeping quarters with a TB patient increased their risk of disease (OR 0.46, 0.27 – 0.78) or recognise TB as an infectious disease (OR 0.65, 0.39 – 1.08). A higher proportion of cases than controls held the mistaken traditional belief that a non-infectious form of TB caused the disease (OR 1.69, 1.02 – 2.78).ConclusionsThe knowledge, attitudes and practices of contacts and TB patients influence their ongoing participation in contact investigation. TB case detection policies in high-prevalence settings can be strengthened by systematically evaluating and addressing locally important barriers to attendance.Trial registrationAustralian New Zealand Clinical Trials Registry, ACTRN12610000600044.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-0816-0) contains supplementary material, which is available to authorized users.

BackgroundTo control multidrug resistant tuberculosis (MDR-TB), the drug susceptibility profile is needed to guide therapy. Classical drug susceptibility testing (DST) may take up to 2 to 4 months. The GenoType® MTBDRplus test is a commercially available line-probe assay that rapidly detects Mycobacterium tuberculosis (MTB) complex, as well as the most common mutations associated with rifampin and isoniazid resistance.We assessed sensitivity and specificity of the assay by using a geographically representative set of MTB isolates from the South of Vietnam.MethodsWe re-cultured 111 MTB isolates that were MDR, rifampin-resistant or pan-susceptible according to conventional DST and tested these with the GenoType® MTBDRplus test.ResultsBy conventional DST, 55 strains were classified as MDR-TB, four strains were rifampicin mono-resistant and 52 strains were susceptible to all first-line drugs. The sensitivity of the GenoType® MTBDRplus was 93.1% for rifampicin, 92.6% for isoniazid and 88.9% for the combination of both; its specificity was 100%. The positive predictive value of the GenoType® MTBDRplus test for MDR-TB was 100% and the negative predictive value 90.3%.ConclusionsWe found a high specificity and positive predictive value of the GenoType® MTBDRplus test for MDR-TB which merits its use in the MDR-TB treatment program in Vietnam.

Consecutive fluoroquinolone (FQ)-resistant isolates (n ‫؍‬109Fluoroquinolones (FQs) are the most promising antituberculous therapeutic agents to be developed in 40 years (9, 31). They are widely used for the treatment of multidrug-resistant (MDR) tuberculosis (TB) despite the lack of clinical trials evaluating optimal doses, duration, and combinations (10,28,31 There is concern about levels of preexisting FQ-resistant TB in regions with high drug resistance rates because these drugs are often available over the counter and are additionally prescribed as broad-spectrum antibiotics for the treatment of undiagnosed respiratory infections (4,5,11,17,23,27,29).Vietnam has some of the highest primary drug resistance rates for Mycobacterium tuberculosis in the world, with over 35% of primary isolates being resistant to one or more first-line drugs (21,26). Despite this, MDR TB rates remain relatively low, at 2.7% nationally, and the National Tuberculosis Program has achieved World Health Organization (WHO) targets for the detection and cure of TB for the last 10 years (14). An expanded MDR TB management program (formally DOTS-PLUS) will be piloted in the near future; however, the success of standardized regimens will depend heavily on preexisting levels of resistance to the most effective second-line agents, the FQs. At present, no data exist on FQ-resistant TB in Vietnam.In mycobacteria, the FQs bind to DNA gyrase and inhibit DNA replication. Reports in the literature show that the majority (approximately 60%) of FQ-resistant M. tuberculosis isolates carry mutations in the quinolone resistance-determining region (QRDR) of the gyrA gene, and a small number have mutations in the gyrB gene (10). It was previously postulated that efflux pump mechanisms account for FQ resistance in isolates with wild-type gyrAB genes (6).While adherence remains the single most important factor in the emergence of drug-resistant TB, a factor contributing to