Detection of Genetic mutations in inhA and katG for Isoniazid and its Association with Rifampicin Resistance in Tuberculosis Confirmed by Line Probe Assay-its Rationality or Isoniazid Prophylaxis Empirical or DST Guided

Out of 442 cases of rifampicin resistant MTB strains 410 cases showed Isoniazid resistance. Out of which exclusive involvement with inhA was seen in 32 cases. 19 cases showed involvement of both inhA as well as katG resistance 359 cases accounting to 87.5% showed exclusive involvement of katG thereby conferring high degree of resistance. The higher percentage of katG induced Isoniazid resistance among the Rifampicin resistant strains depicts the spread of higher degree of Isoniazid resistance. The question remains how effective would be the Isoniazid prophylaxis in pediatric age group in this scenario. The analysis has shown that only around 14.93% cases reflected exclusive mutations at around 15 and 16 regions of the inhA gene and MUT3 accounted to a percentage of 60.3% among the inhA dependant isoniazid resistance.