Mutational analysis of gyrB at amino acids: G481A & D505A in multidrug resistant (MDR) tuberculosis patients.

BACKGROUND

The MDR (multidrug resistance) tuberculosis is a serious public health concern. Fluoroquinolones are in use to treat tuberculosis, but M. tuberculosis strains have now become resistant due to several mutations in different genes. We evaluated mutations in gyrB gene at amino acid positions G481A and D505A of M. tuberculosis by semi-multiplex allele specific (MAS) PCR.

METHODS

The information on gender, age, type of tuberculosis (TB), positive/negative for MDR-TB and HIV infection was gathered. The genomic DNA isolation from sputum culture samples (n=53) was carried out by non-column based method. The gyrB mutations were investigated by using self-designed primers in semi MAS-PCR, at mentioned amino acid positions.

RESULTS

There were 38% male patients and 62% were female patients. Most of MDR-TB patients (58.5%) were in the age between 16-30years. There were 90.5% cases of pulmonary TB and 9.4% cases of extra pulmonary TB. Only 1.8% patients were co-infected with HIV. The 24 samples had mutation in gyrB gene out of 53 (45.28%), on both of positions of amino acids Gly481Ala and Asp505Ala. All samples had mutations at Gly481Ala, whereas, 24 samples (45.28%) had mutations at Asp505Ala.

CONCLUSION

Mutations at amino acids positions 481 and 505 were involved in MDR-TB, which could further develop into an extensively-drug resistance (XDR) TB. Therefore, there is a need to explore all mutations in gyrB gene in MDR-TB, because it can result in a Fluoroquinolones resistance.