Clinical response to aminoglycoside therapy: importance of the ratio of peak concentration to minimal inhibitory concentration

J Infect Dis. 1987 Jan;155(1):93-9. doi: 10.1093/infdis/155.1.93.


In an examination of the relationships among plasma aminoglycoside concentrations, the minimal inhibitory concentration (MIC) for the infecting organism, and therapeutic outcome, data were analyzed from 236 patients with gram-negative bacterial infections who were participants in four clinical trials of gentamicin, tobramycin, and amikacin. Clinical response to therapy occurred in 188 (80%) patients. Elevated maximal and mean peak aminoglycoside concentration/MIC ratios were strongly associated with clinical response (P less than .00001 and P less than .0001, respectively). A graded dose-response effect was found between an increasing maximal peak concentration/MIC ratio and clinical response. By logistic regression the peak concentration/MIC ratios were associated significantly with clinical response after adjustment for underlying severity of illness and other factors correlated with response. These results demonstrate that a high peak concentration relative to the MIC for the infecting organism is a major determinant of the clinical response to aminoglycoside therapy.

Publication types

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

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Amikacin / blood
  • Amikacin / pharmacology
  • Amikacin / therapeutic use*
  • Bacterial Infections / drug therapy*
  • Bacterial Infections / microbiology
  • Clinical Trials as Topic
  • Double-Blind Method
  • Female
  • Gentamicins / blood
  • Gentamicins / pharmacology
  • Gentamicins / therapeutic use*
  • Gram-Negative Bacteria / drug effects*
  • Gram-Negative Bacteria / isolation & purification
  • Humans
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Random Allocation
  • Tobramycin / blood
  • Tobramycin / pharmacology
  • Tobramycin / therapeutic use*


  • Gentamicins
  • Amikacin
  • Tobramycin