Genotypic assessment of Drug Resistant Tuberculosis in Baghdad and other Iraqi provinces using low-cost and density (LCD) DNA microarrays

We report on a molecular investigation carried out to ascertain the prevalence of drug resistant TB and the specific gene mutations responsible for resistance to rifampicin (RIF) and/or isoniazid (INH) in Iraq. One hundred and ten clinical isolates from category II TB cases from Baghdad (58%) and several Iraqi provinces (42%) were analyzed using colorimetric, low-cost and density (LCD) microarrays (MYCODirect and MYCOResist LCD-array kits, Chipron GmbH, Germany) to identify the point mutations responsible for resistance in Mycobacterium tuberculosis isolates. Seventy-six patients (69.1%) had resistant strains, of which 40 (36%) were MDRTB. Where mono-resistance was identified, it was found to be predominantly to RIF (83%). The most common mutations were rpoB S531L (50%), inhA C15T (25%), and katG S315T (15%). The most common MDRTB genotypes were rpoB S531L with inhA C15T (60%) and rpoB S531L with katG S315T (20%). Where phenotypic analysis of clinical isolates was also performed, genotypic data were found to show excellent correlation with phenotypic results. Correlation was found between the MYCOResist LCD-array and GenoType MTBDRplus for detection of resistance to RIF. Our study shows MDRTB in 36% of category II TB cases in Baghdad and surrounding Iraqi provinces which reflects World Health Organization (WHO) findings based on phenotypic studies. Diagnosis of TB and MDR-TB using culture-based tests are a significant impediment to global TB control. The LCD arrays investigated herein are easy to use, sensitive and specific molecular tools for TB resistance profiling in resource-limited laboratory settings.<br/

An Integrated Approach to Rapid Diagnosis of Tuberculosis and Multidrug Resistance Using Liquid Culture and Molecular Methods in Russia

Objective: To 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. Methods: Performance 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. Findings: 698 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). Conclusion: With 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. © 2009 Balabanova et al

Considering best practice standards for routine whole-genome sequencing for TB care and control

TB is a priority pathogen for the application of whole-genome sequencing (WGS) into routine public health practice. In low-incidence settings, a growing number of services have begun to incorporate routine WGS into standard practice. The increasing availability of real-time genomic information supports a variety of aspects of the public health response, including the detection of drug resistance, monitoring of laboratory and clinical practices, contact tracing investigations and active case finding. Optimal structures and approaches are needed to support the rapid translation of genomic information into practice and to evaluate outcomes and impact. In this consensus paper, we outline the elements needed to systemically incorporate routine WGS into the TB public health response, including the sustainability of services, multidisciplinary team models and monitoring and evaluation frameworks. If integrated in an efficient and thoughtful manner, routine WGS has the potential to significantly improve clinical TB care for individuals and the overall public health response