Comparative study of new benzenesulphonamide fluoroquinolones structurally related to ciprofloxacin against selected ciprofloxacin-susceptible and -resistant Gram-positive cocci

The in vitro activities of benzenesulphonamide fluoroquinolones (BSFQs) I–III, new fluoroquinolones with a p-substituted benzenesulphonyl moiety attached to the C7 piperazinyl ring of ciprofloxacin, were assessed in comparison with those of N-sulfanilylpiperazinyl fluoroquinolone (NSFQ)-105 and ciprofloxacin for 133 Gram-positive clinical isolates. NSFQ-105 and BSFQ-I were the most active drugs. They were 16- to 64-fold more active than ciprofloxacin against Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, including ciprofloxacin-resistant strains, and Streptococcus pneumoniae (eight- to 32-fold). A high degree of correlation was found between the MICs of the new compounds and ciprofloxacin for Staphylococcus spp. and E. faecalis. Staphylococci and enterococci exhibit cross-resistance to BSFQs and ciprofloxacin.