A COLLABORATIVE STUDY OF THE INVITRO SENSITIVITY TO RP 59500 OF BACTERIA ISOLATED IN 7 HOSPITALS IN FRANCE

The in-vitro activity of RP 59500 was determined against 1051 recent clinical bacterial isolates. The susceptibility to RP 59500 was determined with an agar dilution technique for all the isolates, while MICs and MBCs were determined for 82 selected strains in broth. Isolates of both Staphylococcus aureus and coagulase- negative staphylococci appeared to be potentially susceptible to RP 59500, indepen-dent of susceptibility to methicillin or MLS resistance. (S. aureus: methicillin- sensitive, MIC90, 1.0 mg/L; methidllin-resistant, MIC90, 1.0 mg/L; coagulase-negative staphylococci: methicillin-sensitive, MIC90, 1.0 mg/L; methidllin-resistant, MIC90 0.5 mg/L). Lancefield group A, B, C and G streptococd (MIC90 0.5 and MIC90 1.0 mg/L) and Streptococcus pneumoniae (MIC50 0.5 and MIC90 1.0 mg/L) appeared to be susceptible to RP 59500. Some Streptococcus spp. and enterococd as well as Listeria monocytogenes were inhibited by a higher concentration of RP 59500 (enterococd: MIC90, 4 mg/L, range 0.125-16 mg/L). Comparatively low MICs were seen when Legionella spp. Neisseria gonorrhoeae and Gardner ella vaginalis were tested. Broth dilution M1C/MBC determinations showed no evidence of tolerance, as MIC values were within two dilutions of MBC values. RP 59500 might be a useful compound in the treatment of infections caused by a range of Gram-negative and Gram-positive bacteria, including those resistant to methicillin and/or macrolides. © 1992 Oxford University Press.