Effect of salicylate on antibacterial activity of different antibiotics

Abstract

Susceptibility ofPseudomonas aeruginosa, Staphylococcus aureus, andBacillus subtilis to gentamicin and cefotaxime was affected by salicylaye. In presence of salicylaye (15 mM) and gentamicin (1.0 ug/ml), log efficiency of plating (log E.O.P.s) for the tested bacteria were −1.24, −2.17 and −1.66 respectively. The activity of cefotaxime againstBacillus subtilis was reduced (log E.O.P.=1.33). The highest potentiating effects of salicylaye were shown when using gentamicin againstStaphylococcus aureus, cefotaxime againstPs. aeruginosa, log E.O.P.s were −3.0, and −2.4, respectively. On the other hand, no significant effects were detected with cefotaxime againstStaphylococcus aureus (log E.O. P.=−0.04). No significant killing was shown in presence of gentamicin or salicylaye alone. There was no significant effect for salicylaye on MICs (By broth dilution) could be observed except in case of gentamicin againstStaphylococcus aureus, which was reduced from 0.02 ug/ml to 0.0012 ug/ml. These results raise the concern that high concentrations of salicylaye in patients might interfere with antibiotic therapies.