Treatment of Mycobacterium avium complex infection: do the results of in vitro susceptibility tests predict therapeutic outcome in humans?

J Infect Dis. 1996 Mar;173(3):677-83. doi: 10.1093/infdis/173.3.677.


The ability of various in vitro methods of antibiotic susceptibility testing to predict therapeutic outcome in patients infected with Mycobacterium avium complex (MAC) was evaluated. Pretreatment bloodstream MAC isolates from 38 patients with AIDS, previously treated in a randomized fashion with either ethambutol, rifampin, or clofazimine, were tested by three conventional methods using broth or agar, as well as by cocultivation with macrophages. The results obtained with each method were compared with the quantitatively determined bacteriologic response to the administration of the single agent in humans. None of the conventional in vitro susceptibility methods was predictive of therapeutic outcome, while the results of cocultivation with macrophages were of moderate predictive value. The positive predictive value of a response in humans based on a response in macrophages (defined by > or = to 1.0 log reduction in baseline colony counts after 5 days of treatment) was 74%. The negative predictive value was 82%.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AIDS-Related Opportunistic Infections / complications
  • AIDS-Related Opportunistic Infections / drug therapy
  • Antibiotics, Antitubercular / therapeutic use
  • Antitubercular Agents / therapeutic use
  • Bacteremia / complications
  • Bacteremia / drug therapy
  • Clofazimine / therapeutic use
  • Ethambutol / therapeutic use
  • Humans
  • In Vitro Techniques
  • Macrophages / drug effects
  • Macrophages / microbiology
  • Microbial Sensitivity Tests / methods*
  • Mycobacterium avium Complex / drug effects
  • Mycobacterium avium Complex / isolation & purification
  • Mycobacterium avium-intracellulare Infection / complications
  • Mycobacterium avium-intracellulare Infection / drug therapy*
  • Rifampin / therapeutic use


  • Antibiotics, Antitubercular
  • Antitubercular Agents
  • Ethambutol
  • Clofazimine
  • Rifampin