Incorporation of a bicyclo[ 1.1. llpent- l-y1 group at the N- 1 position of quinolone antibacterial agents affords compounds with potent activity. One of these analogs, U-87947& exhibits enhanced activity relative to that of ciprofloxacin against gram-positive aerobic bacteria and anaerobic organisms. Time-kill kinetic studies reveal that U-87947E is exquisitely bactericidal against ciprofloxacin-resistant S&&yZococcus uureus.