Comparison of minimum inhibitory concentration and postantibiotic effect of eyedrops on isolates in National Surveillance of Infectious Keratitis in Japan]

To determine the minimum inhibitory concentration (MIC) and postantibiotic effect (PAE) of antibiotic eyedrops against various isolates from infectious keratitis samples.MIC and postantibiotic bactericidal effect (PABE)/postantibiotic fungicidal effect (PAFE) after 4 min of exposure to nine antibacterial eyedrops or four antifungals were examined using 100 clinical isolates collected by the National Surveillance of Infectious Keratitis in Japan in 2003.The PABEs of tobramycin and micronomicin sulfate showed better results than other drugs, and the other drugs demonstrated various PABEs depending on the bacterial strains; in particular most drugs showed low PABE against Serratia marcescens. There were no significant differences between PABEs of methicillin-resistant and methicillin-susceptible Staphylococci. Also there was no statistical correlation between MIC and PABE of Staphylococci. All the antifungals demonstrated low PAFE against Candida spp.PABE/PAFEs vary among species of microorganisms, and since they have no relation with the usual MIC, various other factors, including species of isolates, actual clinical effects, and prevention of drug-resistance induction, should be considered in the selection of drugs.