Detection of Rifampicin Resistance among Patients with Tuberculosis using GeneXpert MTB/RIF Assay: A Retrospective StudyCorrespondence Address :
Dr. Gayathridevi Durairaj,
Tutor, Department of Microbiology, Stanley Medical College, Chennai, Tamil Nadu, India.
Introduction: Tuberculosis (TB) remains one of the major cause of death worldwide, and the leading causes of mortality in developing countries like India. Smear microscopy has certain limits as it requires 10,000 bacilli/mL for positivity, culture methods takes longer turnaround time of around 6-8 weeks. The recent advancement like Genexpert Mycobacterium tuberculosis/Rifampicin (MTB/RIF) Assay, which has more accuracy and analysis where it detects MTB and RIF resistance in smear negative including immunosuppressive patients even with a volume of 138 cfu (colony forming units)/mL in less than two hours. World Health Organisation (WHO) also recommended new Cartridge Based Nucleic Acid Amplification Test (CB-NAAT) on 2010 and named as GeneXpert system for diagnosis of TB.
Aim: To evaluate the patterns of RIF Resistance by GeneXpert as a Rapid and primary screening test in TB patients.
Materials and Methods: Both pulmonary and extra pulmonary samples were subjected to AFB (Acid Fast Bacilli) smear microscopy before being tested for GeneXpert MTB/RIF Assay. MTB detected samples were further tested at National Institute for Research in Tuberculosis (NIRT) to confirm RIF resistance and to find out associated resistance to Isoniazid and other second line drugs like fluroquinolones, kanamycin, capreomycin and amikacin. All statistical analysis were performed using Statistical Package for the Social Sciences (SPSS) version 15.0.
Results: A total of 8140 samples were tested for CB-NAAT, MTB was not detected in 4414 samples, MTB detected and RIF Sensitive in 3554 samples, MTB detected and RIF resistance in 172 samples. Among these RIF Resistant samples 97% were retreatment patients and the primary drug resistance was less common. HIV/TB co-infected contributes to 1% of resistance and there was no gender preponderance. RIF mono-resistance was found in majority of patients.
Conclusion: Genexpert has higher specificity for early detection of RIF resistance as a surrogate marker of MDR-TB to initiate early treatment and prevent transmission of Multi Drug Resistance (MDR) strains.
Cartridge based nucleic acid amplification test, Multidrug resistance tuberculosis, Mycobacterium tuberculosis
Date of Submission: Apr 18, 2020
Date of Peer Review: May 17, 2020
Date of Acceptance: Jul 22, 2020
Date of Publishing: Sep 01, 2020
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? NA
• Was informed consent obtained from the subjects involved in the study? NA
• For any images presented appropriate consent has been obtained from the subjects. NA
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- Indian Science Abstracts (ISA)
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- Popline (reproductive health literature)