In vitro antibacterial activity of trovafloxacin and five other fluoroquinolones

The in vitro inhibitory and bactericidal activities of the investigational fluoroquinolone trovafloxacin were studied and compared with those of five other fluoroquinolones (ciprofloxacin, ofloxacin, pefloxacin, rufloxacin and sparfloxacin) against a wide range of clinical isolates from Italian hospitals. Against gram-positive bacteria, trovafloxacin was overall more active than the other antibiotics tested, including sparfloxacin, another gram-positive-oriented fluoroquinolone, and was active against all ciprofloxacin-resistant streptococci, enterococci, and listeriae, all ciprofloxacin-resistant Staphylococcus aureus isolates and most ciprofloxacin-resistant coagulase-negative staphylococci. Its antistaphylococcal activity was not affected by oxacillin resistance or susceptibility of the isolates, nor was its antipneumococcal activity affected by whether isolates were susceptible or resistant to penicillin. Against gram-negative bacteria, trovafloxacin retained a high potency mostly comparable with that of ciprofloxacin. Rufloxacin and pefloxacin were less active than the other fluoroquinolones against most test strains of both gram-positive and gram-negative organisms. Trovafloxacin minimal bactericidal concentrations usually equalled or exceeded by 2-4 times the minimal inhibitory concentration values, indicating that the compound is overall highly bactericidal.