A relationship between serum gentamicin concentrations and minimal inhibitory concentration.
Since there are few widely accepted guidelines upon which to base therapeutic decisions and adjust for the many variables which may influence the ultimate therapeutic outcome, and few studies have evaluated what the optimal peak concentration-to-MIC ratio should be, pharmacokinetic parameters were estimated from pre- and post-dose concentrations measured in 30 orthopaedic patients, receiving gentamicin. The fluorescence polarization method was used, and simultaneous determination of the MIC (minimal inhibitory concentration) has been made. When Gram(-) microorganisms were incriminated for the infection, the optimal peak concentration exceeded the MIC by more than 3-fold in our serum samples. In Gram(+) bacteria, the peak antibacterial activity usually obtained tended to be lower (between 1.5 and 2). No correlation was found for the nadir bacteriostatic level. Our investigations showed that the peak bacteriostatic activity correlated well with response to therapy. Based on these findings, the peak antibacterial activity should therefore be between 1.5 and 2 for Gram(+) and greater than 3-fold for Gram(-) microorganisms, and these values seem to be effective for eradication of the infection.
Bezirtzoglou
E
E
Department of Microbiology, Medical School, University of Ioannina, Ioannina, Greece.
Golegou
S
S
Savvaidis
I
I
Bezirtzoglou
C
C
Beris
A
A
Xenakis
T
T
D000900:Anti-Bacterial Agents / Q000097:blood / Q000493:pharmacokinetics*; D003404:Creatinine / Q000097:blood; D004334:Drug Administration Schedule; D005260:Female; D005839:Gentamicins / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008826:Microbial Sensitivity Tests
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D003404:Creatinine