ABSTRACT
Objective To study the effect of microscopic observation drug susceptibility assay (MODS)for testing Mycobacteri-um tuberculosis in sputum ,and to evaluate its clinical value .Methods A total of 150 sputum samples were collected from patients with pulmonary tuberculosis ,and Mycobacterium tuberculosis were detected by Lowenstein-Jensen (L-J) method and MODS ,and compared the results of the two methods .Results The concordance rates of the test results of sputum sample between MODS and L-J was 77 .8% .The sensitivity and specificity of MODS were 93 .3% and 70 .0% ,positive predictive value (PPV ) was 60 .8% , negative predictive value (NPV) was 95 .4% ,as well as accuracy by MODS was 77 .8% .Conclusion MODS assay could be used as a rapid tuberculosis detection method ,with rapid ,sensitive ,simple ,and other advantages .
ABSTRACT
Background: The converging epidemics of HIV and tuberculosis (TB) pose one of the greatest public health challenges of our time. Rapid diagnosis of TB is essential in view of its infectious nature, high burden of cases, and emergence of drug resistance. Objective: The purpose of this present study was to evaluate the feasibility of implementing the microscopic observation drug susceptibility (MODS) assay, a novel assay for the diagnosis of TB and multi-drug-resistant tuberculosis (MDR-TB) directly from sputum specimens, in the Indian setting. Materials and Methods: This study involved a cross-sectional, blinded assessment of the MODS assay on 1036 suspected cases of pulmonary TB in HIV-positive and HIV-negative patients against the radiometric method, BD-BACTEC TB 460 system. Results: Overall, the sensitivity, specificity, positive predictive value, and negative predictive value of the MODS assay in detecting MTB among TB suspected patients were 89.1%, 99.1%, 94.2%, 95.8%, respectively. In addition, in the diagnosis of drug-resistant TB, the MODS assay was 84.2% sensitive for those specimens reporting MDR, 87% sensitivity for those specimens reporting INH mono-resistance, and 100% sensitive for specimens reporting RIF mono-resistance. The median time to detection of TB in the MODS assay versus BACTEC was 9 versus 21 days (P < 0.001). Conclusion: Costing 5 to 10 times lesser than the automated culture methods, the MODS assay has the potential clinical utility as a simple and rapid method. It could be effectively used as an alternative method for diagnosing TB and detection of MDR-TB in a timely and affordable way in resource-limited settings.
ABSTRACT
OBJECTIVE To set up and evaluate the microscopic observation drug susceptibility assay(MODS)technology and use it to detect rapidly Mycobacterium tuberculosis(MTB).METHODS The 24-hole cell culture plate method of liquid culture were used to set up MODS technology.The MODS technology was used to detect MTB and non-M.tuberculosis(NMT)isolates comparing with Lowenstein-Jensen(L-J) method.RESULTS When bacterial concentration was 3?103 CFU/ml,the time of reading test-result was the seventh day by MODS;four kinds of NMT(M.phlei,M.kansasii,M.chelonaeand M.marinum) in the liquid medium in the observation was similar to the growth of cording,it was difficult to distinct from the cording of MTB in the liquid medium;When using the 4-Nitro-benzoic acid 800 ?g/ml,thiophene-2-carboxylic acid hydrazine 2.5 ?g/ml for testing conditions,the correct diagnosis can be improved;the test results of clinical isolates by MODS were highly concordance rate with the results of L-J.If the results of L-J was the golden standard,the sensitivity,specificity,positive and negative predictive value as well as accuracy by MODS was 95.7%,100%,100%,99.9% and 97% respectively.CONCLUSIONS The results of MODS in detection of MTB are highly concordance wih the results of L-J method;MODS assay can be used for rapid detection of tuberculosis,with a rapid,simple,inexpensive,and other advantages.