Detection of Drug Resistance Pattern of Mycobacterium Tuberculosis by Genexpert MTB/RIF Solid and Liquid Culture in Extrapulmonary Tuberculosis

Abstract

Background: Tuberculosis (TB) remains one of the deadliest communicable diseases. Tuberculosis is caused by Mycobacterium tuberculosis and classified as Pulmonary Tuberculosis (PTB) and Extra Pulmonary Tuberculosis (EPTB). EPTB account for 15-20 % cases of tuberculosis. EPTB diagnosis is challenging due to inadequate sample volume, pauci-bacillary nature and unusual clinical presentation. There are number of tests available for the diagnosis of EPTB but conventional microscopy has low sensitivity and although culture is gold standard method, it takes longer time for yielding positive result. On the other side, GeneXpert due to its rapidity and sensitivity help in early diagnosis and management of tuberculosis. Culture of Mycobacterium Tuberculosis Complex (MTBC) is the accepted reference standard for confirmation of tuberculosis infection and is necessary for Drug Susceptibility Testing (DST). Although solid media has been used for over 100 years, liquid culture media is increasingly being introduced in low and middle income countries for rapid detection of MTBC. To compare the efficacy of solid culture method using Lowenstein Jensen (LJ) media with GeneXpert and liquid culture method using Mycobacterium Growth Indicator Tube (MGIT) 960 for detection of Mycobacterium tuberculosis. Materials and methods: In this cross sectional study 118 suspected EPTB samples including CSF, lymphatic aspirate, pleural fluid, ascitic fluid, synovial fluid, pus were collected. Smear microscopy, culture both in solid media and liquid media using MGIT 960 method and GeneXpert machine were done. Moreover antitubercular drug sensitivity test was done by proportion method in L-J media. Results: Out of 118 samples, GeneXpert detetcs 26 (22.03%) where as the liquid MGIT 960 method detects 27 (22.88%) and solid culture detects 26 (22.03%) positive samples for Mycobacterium tuberculosis. 01 (1.8%) case was detected as multidrug resistant TB. Conclusion: GeneXpert have significant role in diagnosing EPTB patient within shorter period of time. But GeneXpert can detect only rifampicin resistance where as DST in L-J media detects other first line drugs sensitivity too. Liquid culture method using MGIT 960 yields more positive result than solid culture, also liquid culture shows rapid identification of Mycobacterium tuberculosis.

Chatt Maa Shi Hosp Med Coll J; Vol.23 (2); July 2024; Page 65-68