In vitro activity of RP59500, an injectable streptogramin antibiotic, against vancomycin-resistant gram-positive organisms.
The in vitro activity of RP59500, a streptogramin antibiotic, against 146 clinical isolates of vancomycin-resistant gram-positive bacteria was examined. Five strains of the species Enterococcus casseliflavus and Enterococcus gallinarum, for which the MIC of vancomycin was 8 micrograms/ml, were also studied. Twenty-eight vancomycin-susceptible strains of Enterococcus faecalis and Enterococcus faecium were included for comparison. The drug was highly active against Leuconostoc spp., Lactobacillus spp., and Pediococcus spp. (MICs, < or = 2 micrograms/ml). RP59500 was more active against vancomycin-susceptible strains of E. faecium than E. faecalis (MICs for 90% of the strains [MIC90s], 1.0 versus 32 micrograms/ml). Vancomycin-resistant strains of E. faecalis were as resistant to RP59500 as vancomycin-susceptible strains (MIC90, 32 micrograms/ml), but some vancomycin-resistant E. faecium strains were relatively more resistant to the new agent (MIC90, 16; MIC range, 0.5 to 32 micrograms/ml) than were vancomycin-susceptible organisms of this species.
Collins
L A
LA
Department of Medicine, New England Deaconess Hospital, Boston, Massachusetts 02215.
Malanoski
G J
GJ
Eliopoulos
G M
GM
Wennersten
C B
CB
Ferraro
M J
MJ
Moellering
R C
RC
D004352:Drug Resistance, Microbial; D016983:Enterococcus / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D014640:Vancomycin / Q000494:pharmacology*; D014769:Virginiamycin / Q000494:pharmacology* / Q000627:therapeutic use
D014769:Virginiamycin; C062940:quinupristin-dalfopristin; D014640:Vancomycin