Abstract
ObjectiveTo analyse the feasibility, cost and performance of rapid tuberculosis (TB) molecular and culture systems, in a high multidrug-resistant TB (MDR TB) middle-income region (Samara, Russia) and provide evidence for WHO policy change.MethodsPerformance and cost evaluation was conducted to compare the BACTEC™ MGIT™ 960 system for culture and drug susceptibility testing (DST) and molecular systems for TB diagnosis, resistance to isoniazid and rifampin, and MDR TB identification compared to conventional Lowenstein-Jensen culture assays.Findings698 consecutive patients (2487 sputum samples) with risk factors for drug-resistant tuberculosis were recruited. Overall M. tuberculosis complex culture positivity rates were 31.6% (787/2487) in MGIT and 27.1% (675/2487) in LJ (90.5% and 83.2% for smear-positive specimens). In total, 809 cultures of M. tuberculosis complex were isolated by any method. Median time to detection was 14 days for MGIT and 36 days for LJ (10 and 33 days for smear positive specimens) and indirect DST in MGIT took 9 days compared to 21 days on LJ. There was good concordance between DST on LJ and MGIT (96.8% for rifampin and 95.6% for isoniazid). Both molecular hybridization assay results correlated well with MGIT DST results, although molecular assays generally yielded higher rates of resistance (by approximately 3% for both isoniazid and rifampin).ConclusionWith effective planning and logistics, the MGIT 960 and molecular based methodologies can be successfully introduced into a reference laboratory setting in a middle incidence country. High rates of MDR TB in the Russian Federation make the introduction of such assays particularly useful.
Highlights
High rates of Multidrug-resistant TB (MDR TB) in the Russian Federation make the introduction of such assays useful
Multidrug-resistant TB (MDR TB), i.e. resistance to at least isoniazid (Inh) and rifampin (Rif), and extensively drug-resistant TB (XDR TB), i.e. Multi-Drug Resistance (MDR) plus resistance to amikacin, kanamycin or capreomycin and a fluoroquinolone, are the most problematic forms of resistance because treatment options are limited and the second-line drugs used for therapy are more toxic, less effective, more expensive, and must be administered for a longer period of time than standard first-line drug therapy [1]
This study describes the feasibility of introduction, diagnostic accuracy and costs of the MGIT rapid culture system for primary specimens and firstline drugs (FLD) drug susceptibility testing (DST), coupled with rapid molecular systems for TB culture identification and detection of resistance to isoniazid and rifampin in Samara, Russia, a middle income region with a high burden of MDR TB [5,9,28]
Summary
Tuberculosis (TB) remains one of the leading causes of morbidity and mortality globally, focused principally, but not exclusively, in the non-industrialized world. Conventional culture and DST on solid media is a slow process, and in high income, low-incidence countries these systems have been supplemented (or replaced) by automated liquid culture systems such as the Becton Dickinson BACTECTM MGITTM 960 system. Greater sensitivity than Lowenstein-Jensen (LJ) solid media, comparable sensitivity to the radiometric Bactec 460 system in detecting Mycobacteria in clinical specimens, and good concordance with both LJ and Bactec 460 DST for firstline drugs (FLD) have been demonstrated in several studies [12,13,14,15,16]
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