Prevalence of multi-drug resistant tuberculosis (MDR-TB) is an alarming public health problem. Delay in diagnosis hinders effective treatment. Molecular methods have led to the development of rapid and reliable diagnostic and drug susceptibility tests (DST).
Aim: To Compare Line Probe Assay (LPA) and Conventional Method of DST for the Diagnosis of MDR-TB.
Methods and Material: Total 105 sputum samples were collected from clinically suspected TB patients and screened for TB using Ziehl Neelsen (ZN) staining. Further all samples were cultured on Media. DNA was extracted from the NALC-NaOH decontaminated sputum samples and was subjected to LPA. DST of culture positive samples was performed against Rifampicin (RIF) and Isoniazid (INH) by the Proportional method.
Results: Out of 105 sputum samples, 82% were found to be positive for Acid Fast Bacilli (AFB) by initial ZN staining. 80% were found to be culture positive and 95% were LPA positive. DST detected lesser (18%) samples positive for MDR-TB, than LPA (24%), from the TB positive samples. However, in case of susceptible and mono-resistant strains both methods gave similar results. In addition, conventional biochemicals and LPA identified 27% and 34% samples as Mycobacteria Other Than Tuberculosis (MOTT) respectively.
Conclusion: LPA is a reliable, rapid, sensitive and easy to perform protocol for detection of MDR TB which strongly facilitates rapid initiation of appropriate treatment for MDR-TB patients, long before the results of conventional DST are available. It can be used for detection of MOTT strains. Though, LPA serves as an early guidance of therapy; it is recommended to be followed by a phenotypic DST for confirmation.