In Silico Analysis of S315T and S315R Mutations of Multidrug-resistant Mycobacterium tuberculosis Clinical Isolates from Karachi, Pakistan

Background: Tuberculosis is one of the most frequent and persistent global diseases causing millions of deaths every year. Pakistan lies at number 6 among the 22 most dominant countries, with multidrug resistance up to 15%. Isoniazid-resistant strains of Mycobacterium tuberculosis are gradually rising and seem to be more prevalent in developing countries. Mutations in the katG gene are considered to be responsible for the accusation of isoniazid resistance in M. tuberculosis. Objectives: The current study was designed to investigate the structural and functional associations of KatG gene mutations (S315R and S315T) and multidrug resistance in M. tuberculosis isolates from Karachi, Pakistan. Results: The present study revealed conformational changes in the structure of the KatG enzyme due to observed mutations, which led to induced alterations in isoniazid binding residues at the active site of the KatG enzyme. Furthermore, substantial changes were observed in interaction energy, ligand-receptor energy, electrostatic energy, salvation energy, and ligand-receptor conformational entropy. All these resultant modifications due to S315R and S315T mutations ultimately reduced the flexibility and stability of proteins at isoniazid-binding residues. Conclusions: This deviation in the consistency of protein texture eventually compromises the enzyme activity. It is well expected that the outcomes of the current study would provide a better understanding of the consequences of these mutations and provide a detailed insight into some previously unknown features.

The Effect of KatG S315t M. Tuberculosis Gene Mutation on Conversion Rate of MDR-TB Patients with Shorter-Course Treatment

Background. Resistance to the INH drug is most often caused by a mutation of the KatG S315T M.Tb gene. MDR TB treatment with short-term WHO mixes using high-dose INH drugs is considered less effective in this mutation condition because it causes high resistance to INH. The effectiveness of MDR TB treatment can be seen from the sputum smear conversion rate. This study was aimed to determine the effect of the S315T katG gene mutation on the treatment response of patients with MDR TB who received WHO short-term alloys at Dr Moh Hoesin general hospital, Palembang, Indonesia. Method. This study uses observational analytic with a prospective cohort approach. The study subjects were MDR TB patients at Dr Moh Hoesin general hospital, Palembang, Indonesia, and a PCR-RFLP examination was performed to see the katG gene, followed by sputum smear evaluation at the end of the first and second months of treatment to assess the speed of conversion. Data analysis using SPSS 25 with the chi-square statistical test. Results. The frequency of katG S315T M.Tb gene mutations was 51.85%. The majority of MDR TB sufferers experience rapid conversion (92.59%). 64.29% of the katG S315T gene mutation group experienced sputum smear conversion after one month, 28.57% after two months, and 7.14% after three months of treatment. There was no significant difference in conversion speed in the two groups (p = 0.741). Conclusion. There was no effect of the S315T M.Tb katG gene mutation on the speed of sputum smear conversion of MDR TB patients who received short-term alloy treatment.

Relationship of Mutation of Kodon S 315 T katG Mycobaterium Tuberculosis Gene with Multidrug Resistance Tuberculosis in South Sumatera

MDR TB is a condition of M. tuberculosis that is resistant to isoniazid and rifampicin. This occurs because of certain genomic mutations in certain Mtb specific genes. Some of the genes that play a role in the INH mutation are the katG gene, the inhA gene, the ahpC gene, the ndh gene and the kasA gene. The most frequent mutation gene is the katG gene, around 50-80%, and the most mutations (64%) are found in the S 315T codon. The aim was to determine the relationship of S315T genotype in the M. tuberculosis katG gene with the incidence of Mtb resistance in MDR TB patients in South Sumatra. This type of research is an observational cross sectional study approach, conducted in Palembang RSMH in collaboration with the Clinical Microbiology Laboratory of FK UNSRI Palembang from January - July 2019. The sample of the case group (MDR TB) was 50 people while the control group (TB SO) was 21 people. Each group was tested for S315T genotype katG M. tuberculosis gene using the PCR-RFLP method with the Mspl enzyme. Visualization of the katG gene in codon 315 in this study was only found in 40 samples, 26 samples in the case group (MDR TB) and 14 samples in the control group (TB SO). Results Genetic frequency distribution in the case group (MDR TB) was 65.38% wildtype and 34.62% mutant, whereas in the control group (TBSO) it was 92.86% wildtype and 7.14% mutant. The 315 coded KatG gene mutation in this study was not related to the incidence of MDR TB, with p = 0.07, an odds ratio of 6.8 (0.77 - 61.40, 95% CI). The conclusions of this study found 315G katG M. tuberculosis codon mutation mutations of 34.62% but not significantly related to the incidence of MDR TB in South Sumatra.

Isoniazid-resistant Mycobacterium tuberculosis: prevalence, resistance spectrum and genetic determinants of resistance

The lack of simple, rapid diagnostic tests for isoniazid-resistant rifampicin-susceptible tuberculosis infection (Hr-TB) can result in low treatment efficacy and further amplification of drug resistance. Based on the clinical data, this study sought to estimate the prevalence of Hr-TB in the general population and characterize the phenotypic susceptibility and genetic determinants of isoniazid resistance in M. tuberculosis strains. Molecular-genetic and culture-based drug susceptibility tests were performed on M. tuberculosis isolates and M. tuberculosis DNA obtained from the patients with pulmonary TB undergoing treatment at the Central Tuberculosis Research Institute between 2011 and 2018. The tests revealed that Hr-TB accounted for 12% of all TB cases in the studied sample. Hr-TB strains were either resistant to isoniazid only (45%) or had multiple resistance to 2–6 anti-TB agents. Resistance to isoniazid was caused by mutations in the katG gene. Based on the literature analysis and our own observations, we emphasize the importance of developing simple molecular drug susceptibility tests capable of detecting simultaneous resistance to rifampicin and isoniazid and the necessity of their translation into clinical practice.

DETECTION OF MUTATIONS IN THE KatG GENE RELATED TO ISONIAZID RESISTANCE OF MYCOBACTERIUM TUBERCULOSIS COLLECTED IN CENTRAL AND SOUTH VIETNAM

Infection of Mycobacterium tuberculosis (MTB) is one of the most common infections in humans. However, the detection rate is only 37% of estimated patients. Currently, Tuberculosic bacteria (TB) are becoming more serious with many TB strains developing multi-drug resistance, and particularly, in case of co-infection with TB and HIV/AIDS. The izoniazid resistant TB strains (INH) also resistant to the other anti-TB antibiotics. The molecular biology methods have allowed rapid and accurate diagnosis of patients infected with drug-resistant TB bacteria. In this study, we used primers katG-F and katG-R designed for amplication of a fragment of 684 bp in katG gene in 7 strains of TB bacteria collected in Pham Ngoc Thach - Ho Chi Minh city and Hue Central hospitals. Sequence analysis of the katG gene fragments showed that 5 samples had substitution mutations at codon 315 (point mutation G to C), leading to the change of amino acid from Serine to Threonine (S315T). In the 5th sample there appeared another mutation at codon 324, changing amino acid Aspartic (D) to Glycine (G) (D324G). In the sample DA1, no mutation has been found in any codon in the katG gene fragment studied. The results obtained in this study may have important implications in changing the treatment regimen and control of tuberculosis in a country with high number of TB patients as in Vietnam.