Effects of subinhibitory concentrations of moxifloxacin in an in-vitro dynamic model

The postantibiotic effect (PAE), sub-MIC effect (SME) and postantibiotic su b-MIC effect (PASME) of moxifloxacin were investigated in an in-vitro dynam ic model reproducing in-vivo elimination kinetics of the antibiotic, The PA E was induced by exposing strains of Staphylococcus aureus, Streptococcus p neumoniae, Escherichia coli and Klebsiella pneumoniae to 5 x MIC of the ant ibiotic for 1.5 hours. After induction, cultures were washed to eliminate t he antibiotic and resuspended into the dynamic model either in the presence or absence of a subinhibitory concentration of the antibacterial agent of 0.5 x MIC. Unexposed controls were treated similarly. PASMEs were constantl y longer than corresponding SMEs, but differences between them were not sta tistically significant. Both PASMEs (mean 11:17 hours, range from 8:17 to 1 4:57) and SMEs (mean 9:23 hours, range from 6:03 to 12:34) had an initial b actericidal effect and were significantly longer than PAEs (mean 1:31 hours , range from 0:21 to 2:14). The primary effect of moxifloxacin sub-MICs app ears to be prevalent in PAE. The possibility of once-daily dosing of the dr ug is strengthened.