Dexamethasone does not alter in vitro antibacterial efficacy of gentamicin.
OBJECTIVE
Aminoglycoside ototoxicity may be mitigated by administration of dexamethasone; however, dexamethasone could theoretically impair its antibacterial properties. The purpose of this experiment was to determine if dexamethasone decreases the antibacterial activity of gentamicin against Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA).


METHODS
In vitro microbiological assay.


METHODS
Four separate trials of minimum inhibitory concentration (MIC) testing were performed for gentamicin against five PA strains and six SA strains, with and without the addition of high and low concentrations of dexamethasone.


RESULTS
MICs were not changed by more than one dilution with the addition of either high or low concentrations of dexamethasone for any of the PA and SA strains.


CONCLUSIONS
Dexamethasone does not impair the antibacterial efficacy of gentamicin for PA and SA. This supports the role of dexamethasone as an oto-protectant with aminoglycoside therapy.
Drobbin
Michael T
MT
Department of Otolaryngology, University of Florida, Gainesville, FL 32610, USA.
Phelan
Sean T
ST
Antonelli
Patrick J
PJ
D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000627:therapeutic use*; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005839:Gentamicins / Q000378:metabolism* / Q000627:therapeutic use*; D006801:Humans; D010033:Otitis Media / Q000188:drug therapy* / Q000382:microbiology*; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013211:Staphylococcus aureus / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D000893:Anti-Inflammatory Agents; D005839:Gentamicins; D003907:Dexamethasone