IN-VITRO ACTIVITY OF A NEW FLUOROQUINOLONE, FLEROXACIN AGAINST HOSPITAL ISOLATES AND REGRESSION CURVE - A MULTICENTER STUDY

Minimal inhibitory concentrations (MICs) of fleroxacin (FLE) were determined by agar dilution for 1261 bacterial strains isolated in 1992 in 4 university hospitals ; in addition, antibiograms by agar diffusion were performed with 5 mug disks. Activity of FLE against nalidixic acid (NAL) susceptible (S) Enterobacteriaceae was close to that of other fluoroquinolones (FQ) (MIC 50 and 90 : 0.12-0.25 mug/ml) ; like for other FQ, this activity was reduced against NAL intermediate and resistant (R) Enterobacteriaceae (4-32). MICs of FLE against P aeruginosa were between 1 and 128 (8-128). FLE had also a good activity against NAL-S A. baumannii (0.12-0.5) but this activity is reduced against NAL-R Acinetobacter (64-128). FLE was highly active against Haemophilus (0.06-0.12), Gonococci (0.03-0.25), Meningococci (0.016-0.03) and B. catarrhalis (0.12-0.25). FLE showed activity close to the currently available FQ against methicillin susceptible Staphylococci (0.25-1) ; the resistant strains (32->128) are usually methicillin resistant. FLE is less effective against Enterococci (4-128), Streptococci (8-16) and Pneumococci (4-8). The coefficient correlation of the regression curve is 0.93; for MIC breakpoints of 1 and 4 mug/ml, zone diameter breakpoints should be 20 and 15 mm.