IN-VITRO ACTIVITY OF PEFLOXACIN AGAINST C LINICAL ISOLATES - PRESENT STATUS - CROSS-RESISTANCE WITH OFLOXACIN AND CIPROFLOXACIN

The antibacterial activities of pefloxacin (PEF), ofloxacin (OFL), cip rofloxacin (CIP) were measured by agar diffusion (5 mug strength disks ) against 6370 non duplicate clinical isolates collected in November 1 991 in 40 hospitals from various areas in France. The MICs of PEF, OFL and CIP were determined by agar dilution against intermediate or resi stant strains to one of the three antibiotics (inhibition zone < 16 mm for PEF, OFL, < 19 mm for CIP). In the Enterobacteriaceae the overall incidence of resistance to PEF (MIC > 4 mg/1) was 8% with important v ariations between the different species : E. coli 2%, Salmonella 0%, E . cloacae 9%, K. pneumoniae 21, P. mirabilis 13%, P. vulgaris 3%, M. m organii 5%, Providencia 61%, S. marcescens 55 %. Among S. aureus, the incidence of resistance was 3% for the methicillin-susceptible strains and 86% for the methicillin-resistant strains. The same applied to co agulase negative Staphylococci : methicillin-susceptible 9%, methicill in-resistant 62%. The frequency of the resistant strains was high amon g P aeruginosa : 40% and A. baumanii : 83%. A high degree of correlati on was observed between the MICs of PEF, OFL and CIP for all the bacte rial species : r = 0,8 - 0,9. No major discrepancies were noted betwee n the clinical categorization, of the activities of the three antibiot ics for the different species except for P. aeruginosa : 4% of the str ains were resistant to pefloxacin and susceptible to ciprofloxacin.