Post-antibiotic effect of the new streptogramin RP 59500.
The post-antibiotic effect (PAE) of RP 59500, a new streptogramin antibiotic, was determined for Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Streptococcus pneumoniae, and Streptococcus pyogenes. A 30 min exposure of Staphylococcus aureus to 5 micrograms/ml of RP 59500 produced a PAE of 1.9-6.9 h, and a 60 min exposure of 2.5 micrograms/ml produced a PAE of 3.2-8 h. A 30 min exposure of 5 micrograms/ml of RP 59500 of coagulase-negative staphylococci produced a PAE of 2.5-7.5 h. PAEs of constitutively erythromycin-resistant staphylococcal isolates were shorter than were the PAEs of highly susceptible isolates. A 30 min exposure to 5 micrograms/ml of RP 59500 produced a PAE of 7.5-9.5 h for Streptococcus pneumoniae and a PAE of greater than 18 h for Streptococcus pyogenes. RP 59500 produced a longer PAE with Staphylococcus aureus than did vancomycin, oxacillin or erythromycin. These results suggest that RP 59500 may be administered less frequently than would be suggested by its half-life.
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Department of Medicine, College of Physicians & Surgeons, Columbia University, New York, New York 10032.
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D002981:Clindamycin / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004917:Erythromycin / Q000494:pharmacology; D005069:Evaluation Studies as Topic; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology; D013210:Staphylococcus / Q000187:drug effects*; D013291:Streptococcus / Q000187:drug effects*; D013997:Time Factors; D014769:Virginiamycin / Q000494:pharmacology*
D014769:Virginiamycin; C062940:quinupristin-dalfopristin; D002981:Clindamycin; D004917:Erythromycin; D010068:Oxacillin