A comparative study of AFB smear and GeneXpert MTB/RIF assay in pulmonary and extrapulmonary specimens and detection of rifampicin resistance in a tertiary care hospital

Abstract

Tuberculosis is a major public health problem worldwide including India causing increased morbidity and mortality. There is a need for rapid identification for early diagnosis and treatment. In this study, GeneXpert MTB/RIF assay is used for rapid identification and was compared with AFB staining (by Zeihl Neelsen method). GeneXpert was used for Mycobacterium tuberculosis (MTB) complex identification and rifampicin detection from smear positive and smear negative patients. Out of 320 patients, 19 patients were acid-fast bacilli (AFB) smear positive and 67 patients detected for MTB by MTB/RIF assay. Rifampicin resistance (RR) was detected in 2 cases out of 62 positive cases by MTB/RIF assay. The test is considered more sensitive for AFB smear positive and showed high level of detection of MTB but less sensitive for AFB smear negative and showed low and medium level of detection of MTB. The GeneXpert is considered as an effective diagnostic tool for rapid diagnosis of MTB and RR in smear negative and positive specimens.

Keywords

• Mycobacterium tuberculosis
• GeneXpert MTB/RIF assay
• rifampicin resistance
• acid fast bacilli staining
• pulmonary
• extrapulmonary