Lab-on-Chip-Based Platform for Fast Molecular Diagnosis of Multidrug-Resistant Tuberculosis.

We evaluated the performance of the molecular lab-on-chip-based VerePLEX Biosystem for detection of multidrug-resistant tuberculosis (MDR-TB), obtaining a diagnostic accuracy of more than 97.8% compared to sequencing and MTBDRplus assay for Mycobacterium tuberculosis complex and rifampin and isoniazid resistance detection on clinical isolates and smear-positive specimens. The speed, user-friendly interface, and versatility make it suitable for routine laboratory use.

Detection of resistance to second-line antituberculosis drugs by use of the genotype MTBDRsl assay: a multicenter evaluation and feasibility study.

The rate of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) has been steadily increasing in countries of the former USSR. The availability of rapid and reliable methods for the detection of drug resistance to second-line drugs is vital for adequate patient management. We evaluated the performance of the Genotype MTBDRsl assay compared to that of phenotypic drug susceptibility testing (Becton Dickinson Bactec MGIT 960 system) with a test panel of 200 Mycobacterium tuberculosis isolates at four sites in Eastern Europe. The interpretability of the Genotype MTBDRsl assay was over 95%. The sensitivity for the detection of resistance to fluoroquinolones, ethambutol, amikacin, and capreomycin varied between 77.3% and 92.3%; however, it was much lower for kanamycin (42.7%). The sensitivity for the detection of XDR TB was 22.6%. The test specificity was over 82% for all drugs. The assay presents a good screening tool for the rapid detection of resistance to individual second-line drugs and can be recommended for use in countries with a high burden of MDR/XDR TB. The sensitivity for the detection of kanamycin resistance needs improvement.

The role of the interferon gamma release assay in assessing recent tuberculosis transmission in a hospital incident.

In 2007, an extensive contact screening investigation into onward transmission of tuberculosis was instigated at a hospital in Northern Ireland following diagnosis of pulmonary multi-drug resistant TB in a healthcare worker. Interferon gamma release assays (IGRAs) were used to test 333 patients and 98 staff. We investigated for evidence of onward transmission and recent infection based on analysis of clinical, demographic and IGRA data. We also described within-patient variability of IGRA results. Among patients and staff, increasing age of patients was the only factor associated with IGRA positivity. Greatest within-subject variability of IU/mL in serially-tested patients/staff was seen in those with a positive IGRA test and this did not correlate with increased exposure to the index case. IGRA positivity being largely explained by increasing age in patients and previous TB contact in staff lends weight to the conclusion that IGRA positivity reflected previous infection rather than recent transmission.