Minimal inhibitory concentration of isoniazid in isoniazid-resistant Mycobacterium tuberculosis isolates from children

Eur J Clin Microbiol Infect Dis. 2007 Mar;26(3):203-5. doi: 10.1007/s10096-007-0257-9.


The aim of the study presented here was to determine the minimal inhibitory concentration of isoniazid for strains of isoniazid-resistant or multidrug-resistant Mycobacterium tuberculosis isolated from children in the Western Cape Province of South Africa. During the period March 2003-October 2005, 45 INH-resistant M. tuberculosis isolates (21 also rifampicin-resistant) were cultured from children less than 13 years of age. Drug susceptibility testing by the radiometric BACTEC 460 method found 11 isolates resistant at 0.1 microg/ml, 27 resistant at 0.2 microg/ml, and seven resistant at > or =5 microg/ml. Thus, the minimal inhibitory concentration of isoniazid for more than 80% of the isoniazid-resistant strains isolated from children in this study was relatively low and could be exceeded by high-dose (15-20 mg/kg) isoniazid regimens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Antitubercular Agents / pharmacology*
  • Child
  • Child, Preschool
  • Drug Resistance, Bacterial
  • Drug Resistance, Multiple, Bacterial
  • Humans
  • Infant
  • Isoniazid / pharmacology*
  • Microbial Sensitivity Tests
  • Mycobacterium tuberculosis / drug effects*
  • Mycobacterium tuberculosis / isolation & purification
  • Rifampin / pharmacology
  • Tuberculosis / microbiology


  • Antitubercular Agents
  • Isoniazid
  • Rifampin