katG (SER 315 THR) gene mutation in isoniazid resistant Mycobacterium tuberculosis

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Isoniazid (INH) and Rifampicin (RFP) are primary drugs for tuberculosis (TB) treatment.
• Mutations in the katG gene at codon 315 are common in INH-resistant Mycobacterium tuberculosis (MTB).
• Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCR-RFLP) is effective for detecting specific gene alterations.

Purpose of the Study:

• To screen for the Ser315Thr mutation in the KatG gene of INH-resistant MTB strains.
• To utilize the PCR-RFLP technique for mutation detection.

Main Methods:

• Analyzed 37 INH-resistant MTB isolates from Nepal.
• Extracted DNA using the SORPOCLEAN protocol.
• Amplified the katG codon 315 region and cleaved with MspI enzyme.
• Visualized restriction fragments via agarose gel electrophoresis.

Main Results:

• The katG Ser315Thr mutation was found in 23 (62.2%) of 37 INH-resistant isolates.
• All isolates were resistant to INH and RFP; 26 and 27 were resistant to Ethambutol (EMB) and Streptomycin (S), respectively.
• Seventeen patients with EMB and S resistant strains harbored the katG gene mutation.

Conclusions:

• High prevalence of the katG Ser315Thr mutation was observed.
• Isolates with this mutation showed simultaneous resistance to RFP.
• The Ser315Thr mutation may serve as a genetic marker for predicting multidrug-resistant TB (MDR-TB).