Impact of isoniazid resistance on virulence of global and south Indian clinical isolates of Mycobacterium tuberculosis.

Unissa, A.N.; Hanna, L.E.

Tuberculosis; 2014; 94; 557-563.

Abstract: Isoniazid (INH) is the only anti-tuberculous drug for which a relationship has been noticed between acquisition of resistance and lack of virulence. Mutation in katG gene is the chief cause for INH resistance in Mycobacterium tuberculosis ( MTB ). Classical studies have demonstrated that INH-resistant (INH r ) mutants with a defective katG gene were catalase deficient and markedly attenuated in guinea pigs. Also, earlier studies on south Indian INH r isolates were shown to have lower virulence and higher susceptibility to H₂ O₂ . However, later studies including that of our's suggest that INH resistance is not always accompanied by compromised virulence and/or survival. Therefore, this review focuses on the influence of INH resistance on virulence of MTB from global and south Indian isolates.

Keywords : INH resistance; Virulence; South Indian isolates; KatG; S315T mutant

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