Antimicrobial activity of subinhibitory concentrations of aminoglycosides against Pseudomonas aeruginosa as determined by the killing-curve method and the postantibiotic effect.
This investigation used the postantibiotic effect (PAE) and killing curves to provide data on the antimicrobial activity of subinhibitory (1/8x, 1/4x and 1/2x minimum inhibitory concentration; MIC) and inhibitory (1x MIC) concentrations of amikacin, gentamicin and tobramycin against Pseudomonas aeruginosa. Subinhibitory concentrations (1/4x and 1/2x MIC) of aminoglycosides demonstrated a reproducible PAE. At 1/4x MIC, the order of duration of the PAE was approximately 15 min for all aminoglycosides, while at 1/2x MIC all three aminoglycosides displayed a similar PAE of approximately 40 min. Killing-curve studies demonstrated that subinhibitory concentrations of aminoglycosides either decrease bacterial growth for several hours (1/4x and 1/2x MIC) or produce stasis of growth for several hours (1/8x MIC). Only inhibitory aminoglycoside concentrations (1x MIC) proved to be bactericidal. Subinhibitory concentrations of aminoglycosides decrease bacterial growth and produce a PAE against P. aeruginosa.
Zhanel
G G
GG
Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada.
Karlowsky
J A
JA
Hoban
D J
DJ
Davidson
R J
RJ
D000583:Amikacin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000032:analysis / Q000494:pharmacology*; D005839:Gentamicins / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D015610:Serum Bactericidal Test; D013997:Time Factors; D014031:Tobramycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D000583:Amikacin; D014031:Tobramycin