MODS ASSAY FOR RAPID DIAGNOSIS OF TUBERCULOSIS AMONG HIV TB CO INFECTED INDIVIDUALS IN A TERTIARY CARE HOSPITAL, ANDHRA PRADESH

Abstract

BACKGROUND: Rapid, reliable, economical methods are required for diagnosisof tuberculosis. The Microscopic Observation of Drug Susceptibility (MODS)assay is a relatively low-cost and simple liquid culture method. The objective ofthis study is to determine the sensitivity and specificity of MODS test in comparison to the Lowenstein- Jensen medium to diagnose tuberculosis amongHIV seropositive individuals in GSL Medical College.METHODS: Sputum specimens were evaluated using smear microscopy, cultureon Lowenstein-Jensen medium and MODS assay. A study subject is consideredto have tuberculosis if at least 1 culture on Lowenstein- Jensen mediumor MODS technique showed growth for M. tuberculosis.RESULTS: Spot Morning sputum samples were obtained from 873 HIV seropositive individuals. Two hundred and ninety seven (34%) [95% CI=30.8 – 37.2] patients were culture positive by MODS and 277 (32%) [95% CI=28.7 – 34.9] were culture positive on LJ slopes (P < 0.001). MODS sensitivity was 99.3% and specificity was 96.3%. Mean times for TB detection were 21 days (range 15 – 25 days) and 12 days (range 7- 15 days) for culture on Lowenstein-Jensen medium and MODS (including drug susceptible testing) respectively (P<0.001). Culture contamination was low in MODS assay than culture on Lowenstein-Jensen medium (1.35 vs. 15.6%; P<0.001). Drug resistance was 12.6% for both RIF and INH, 12.6 % for RIF and 15% for INH.CONCLUSIONS: The MODS assay is a relatively simple test whose good performance for detection of pulmonary tuberculosis in HIV patients may make it suitable for resource-limited environments.