Comparison of bacteriostatic and bactericidal activity of isoniazid and ethionamide against Mycobacterium avium and Mycobacterium tuberculosis

Am Rev Respir Dis. 1991 Feb;143(2):268-70. doi: 10.1164/ajrccm/143.2.268.


Minimal inhibitory and bactericidal concentrations (MIC and MBC) of isoniazid and ethionamide were determined in 7H12 broth in experiments with 68 Mycobacterium avium strains and 14 wild drug-susceptible M. tuberculosis strains. MICs of isoniazid for M. tuberculosis were from 0.025 to 0.05 microgram/ml, and for M. avium from 0.6 to greater than 10.0 micrograms/ml. MICs of ethionamide for M. tuberculosis were from 0.3 to 1.25 micrograms/ml, and 42.7% of M. avium strains were within the same range. Isoniazid and ethionamide were highly bactericidal against M. tuberculosis, but they had very low bactericidal activity against M. avium.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Colony Count, Microbial
  • Dose-Response Relationship, Drug
  • Ethionamide / pharmacology*
  • Isoniazid / pharmacology*
  • Mycobacterium avium / drug effects*
  • Mycobacterium tuberculosis / drug effects*
  • Osmolar Concentration
  • Radiometry


  • Ethionamide
  • Isoniazid