Prevalence and detection of drug resistant mutations in mycobacterium tuberculosis among patients visiting selected health centres in Nairobi, Kenya
Ogari, Collins Otieno
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Tuberculosis (TB), an ancient scourge of humanity known for several thousands of years, is still a main public health challenge in many countries today even though some progress has been made recently in curbing the disease. Deferred diagnosis, poor treatment regimens and fatality qualify drug-resistant and multi-drug resistant tuberculosis (MDR TB). Unlike other bacterial pathogens, Mycobacterium tuberculosis lacks plasmid mediated mechanisms of resistance. Drug resistance in M. tuberculosis is entirely due to chromosomal changes that occur within the genes, for instance deletions or mutations. These chromosomal modifications influence the drug target or bacterial enzymes that are responsible for activating or customizing the drug. Inadequate or incomplete chemotherapy also enables M. tuberculosis to become drug resistant due to mutants that exist by nature in the mycobacterial community. Since the frequency of mutations vary geographically and limited data is available on the patterns of gene mutation in Kenya, insight of the rates of geographic specific mutations can enable the evolution of internal, PCR-based techniques for targeting mutations relevant in a specific setting. In addition to crafting new molecular biology-based techniques for the examination of MDR tuberculosis and advancement of new drugs, heightened rates of MDR and extremely-drug resistant tuberculosis (XDR TB) worldwide need to be controlled and profiled. Therefore, the main objective of this study was to evaluate the prevalence and detection of drug resistant mutations in Mycobacterium tuberculosis among patients visiting selected health centers in Nairobi, Kenya. The current study employed a cross-sectional study design which involved collecting sputum samples from 132 patients visiting Mbagathi district hospital and Chandaria community hospital. Of the 132 patients, male subjects were seventy-two (54%), while women were 60 (46%), all averaging 35 years and having a range of 18 to 60 years. Overall, 132 sputum samples were collected from patients who were all smear-positive for pulmonary TB and included for processing. Sample processing involved decontamination of collected sputum samples with NALC/NaOH/sodium citrate, thereafter, direct sputum smear microscopy using Ziehl-Neelsen stain for Acid Fast Bacteria (AFB). DNA was then extracted from the positive samples and analyzed by means of Genotype MTBDRplus (Rapid test for rifampicin and/or isoniazid resistance) and Genotype MTBDRsl (Rapid test for fluoroquinolones, aminoglycosides, and low-level kanamycin resistance in addition to confirmation of M. tuberculosis). Data analysis was carried out using chi-square test to analyze the difference in mutations detected. In total, the prevalence for the resistance to first and second-line TB drugs was 1.5% (2/132). Rifampicin resistant strain had the rpoB mutation S531L; isoniazid resistant strains had the mutations katG S315T; AG/CP resistant strains had the rrs mutation G1484T. The molecular analysis indicates confirmation of the transmission of resistant strain. The data suggested that there is homogeneity when it comes to the type of drug resistance and mutation that occurs in the region. This calls for intensified drug resistance surveillance and drug adherence among patients infected with TB. In addition, there is an urgent need for randomized controlled trials to discover the most effective treatment regimen for managing INH resistant TB.