Multiplex PCR for Rapid Diagnosis of Drug Resistant Mycobacterium Tuberculosis.

Abstract

OBJECTIVE\nTo evaluate a multiplex PCR for rapid diagnosis of drug resistant mycobacterium tuberculosis (MTB) strain.\n\n\nSTUDY DESIGN\nCross-sectional observational study.\n\n\nPLACE AND DURATION OF STUDY\nDepartment of Microbiology, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from January to September 2018.\n\n\nMETHODOLOGY\nOver a period of 8 months, a total of 84 cultured positive samples were included in the study using nonprobability sampling techniques. MTB isolates were phenotypically characterised using MGIT 960 system for antituberculosis agents including rifampicin (RIF), isoniazid (INH), ethambutol (EMB) and Streptomycin. The DNA was extracted using Gentra system DNA extraction kit. The multiplex PCR was optimised for genetic characterisation of MTB samples for rpo B (rifampicin), kat G (isoniazid) and emb B (ethambutol) gene. The gel electrophoresis was performed to observe comparative banding pattern of amplified gene products.\n\n\nRESULTS\nFor detecting drug resistance, the specificity and sensitivity of multiplex PCR in isolates was 100% and 100% for rifampicin, 100% and 71% for isoniazid, and 100% and 60% for ethambutol, respectively. When compared to phenotypically resistance results, the positive predictive value (PPV) was 100% each and the negative predictive value (NPV) was calculated to be 100%, 74% and 71% for RIF, INH and EMB, respectively.\n\n\nCONCLUSION\nMultiplex PCR is a useful gadget for quick determination of drug-resistant TB in specimens, hence permitting an initial therapeutic approach. However, for accurate management of patients, phenotypic method should be used to confirm results.