Assessment of Conventional and Molecular Methods in the Routine Management of Tuberculosis in a High Tuberculosis Burden Setting

Background and aims: India is a high-burden tuberculosis (TB) region and a drug-resistance hotspot.Despite numerous reports of pulmonary tuberculosis (PTB) cases, there needs to be more literatureavailable on the importance of diagnostic methods in the case of extrapulmonary tuberculosis (EPTB). Aprospective study was performed from July ۲۰۱۷ to June ۲۰۱۸ to compare the efficacy of conventionaland molecular methods in detecting PTB and EPTB cases.Methods: Overall, ۱۰۰۰ presumptive PTB and ۴۱۲ EPTB cases were subjected to staining (Ziehl-Neelsen [ZN] and fluorescent staining), culture, GeneXpert, and line probe assay (LPA).Results: The sensitivity, specificity, and strength of association [i.e., kappa (k) value of light-emittingdiode-fluorescent microscopy, ZN, and GeneXpert] were calculated using standard formulae usingsolid culture as the gold standard. The sensitivity of GeneXpert in smear-positive/culture-positive PTBwas comparable with the smear-negative/culture-positive PTB cases (۹۵.۷% vs. ۸۷.۵%) with an overallsensitivity and specificity of ۹۰.۵% and ۹۰.۱% in EPTB cases, respectively. However, sensitivity waslower for pleural fluid (۷۵%) and tissues (۸۵.۷%). In pulmonary instances, ۱۰% (۶.۷% Rifampicin[RIF] + isoniazid [INH] resistant and ۳.۳% INH monoresistant) drug resistance was observed, and nodrug resistance was found in extra-pulmonary samples.Conclusion: Among conventional methods, fluorescent staining is more sensitive than ZN staining,while the sensitivity of GeneXpert varies w.r.t type of sample using culture positivity as the goldstandard. In general, the present study suggests the promotion of universal drug susceptibility testing(DST) for all individuals with TB to control drug-resistant TB.

Keywords:

RNTCP , Culture , Fluorescent staining , ZN staining , GeneXpert , LPA