Interactions of quinupristin-dalfopristin with eight other antibiotics as measured by time-kill studies with 10 strains of Staphylococcus aureus for which quinupristin-dalfopristin alone was not bactericidal.
Quinupristin-dalfopristin (Q-D) and eight other antimicrobial agents were tested alone and in combination with Q-D in time-kill studies against 10 strains of macrolide-lincosamide-streptogramin B-resistant Staphylococcus aureus. Although Q-D is normally a bactericidal drug, it was only bacteriostatic for these isolates. Gentamicin alone was bactericidal against 7 of the 10 strains, and Q-D did not alter that killing effect. However, when vancomycin, cefepime, ceftazidime, imipenem, piperacillin-tazobactam, and ciprofloxacin were bactericidal when tested alone, the killing rates were reduced when combined with Q-D. The clinical significance of this in vitro antagonism is unknown at this time, and more studies are needed.
Fuchs
P C
PC
The Clinical Microbiology Institute, Wilsonville, Oregon 97070, USA.
Barry
A L
AL
Brown
S D
SD
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004347:Drug Interactions; D004352:Drug Resistance, Microbial; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects*; D013997:Time Factors; D014769:Virginiamycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D014769:Virginiamycin; C062940:quinupristin-dalfopristin