Comparative in vitro activity of PD 127391, a new fluoroquinolone agent, against susceptible and resistant clinical isolates of gram-positive cocci.

We examined the in vitro activity of PD 127391, an investigational fluoroquinolone antibacterial agent, against staphylococci (including methicillin-resistant Staphylococcus aureus), enterococci (including beta-lactamase-producing and highly gentamicin-resistant isolates), and streptococci. The compound was active against all organisms tested and compared favorably with antimicrobial agents routinely used to treat infections with these organisms. On the basis of MICs for 90% of the strains tested, PD 127391 was 32-fold more active against all staphylococci, 16-fold more active against methicillin-resistant S. aureus, 8-fold more active against all streptococci, and 4-fold more active against all enterococci than ciprofloxacin. PD 127391 was shown to be more active than sparfloxacin, which in turn was shown to be more active than ciprofloxacin, against these gram-positive cocci. PD 127391 shows promise for the treatment of infections with gram-positive cocci, including organisms which are resistant to other commonly used antimicrobial agents.