Role of line probe assay (LPA) and Genexpert in diagnosis of smear-negative pulmonary tuberculosis-a prospective study
Supriyaa Bhakthavatchalam B, Arun Mohan R, Bhakthavatchalam N
Tuberculosis still remains as a major cause of ill health worldwide causing substantial morbidity and mortality despite a decline in both incidence and prevalence. The dual challenge of low diagnositic sensitivity of Sputum Microscopy and technical challenge of performing TB cultures, particularly in SNPT delays the initiation of treatment. With India being one among 22 countries with highest TB burden globally, MDR-TB poses a global threat in TB control underscoring the importance of prompt and rapid identification of such resistant MTB strains, resulting in treatment failure and poor clinical outcome. So, there is a need for rapid, reliable molecular based tests like GeneXpert & LPA for early diagnosis and institution of treatment, thus preventing the transmission of Drug resistance TB among the vulnerable population. This study aims to compare the Diagnostic Performance of GeneXpert & LPA against the culture methods (MGIT 960) with early detection of drug resistance and its pattern among the SNPT at Dr. B.R. Ambedkar Medical College and Hospital. 100 Patients with Suspected TB with Sputum smear negative samples were randomly selected and subjected to detailed clinical examination, pathological tests, Culture methods (MGIT 960) and molecular testing-GeneXpert & LPA. Further the test results were analysed and performance of each test were compared with MGIT 960(gold standard assay). The diagnostic performance of LPA & GeneXpert were highly sensitive and specific for early detection of MTB complex, particularly MDR strains, leading to effective management and good adherence with short duration of time. Thus LPA is a better alternative to culture with regards to detection of MDR strains and drug resistance pattern.