Isoniazid resistance

Resistance can emerge rapidly if the drug is used alone. High-level resistance is associated with deletion in the katG gene that codes for a catalase-peroxidase involved in the bioactivation of INH. Low-level resistance occurs via deletions in the inhA gene that encodes the target enzyme, an acyl carrier protein reductase. Cross-resistance does not occur between isoniazid and other antitubercular drugs.