In vitro activity of quinupristin/dalfopristin against gram-positive bacteria Haemophilus influenzae and Branhamella catarrhalis in Taiwan.
BACKGROUND
Over the past decade, resistance of Gram-positive cocci to common antibiotics has steadily increased. New antibacterial agents that are active against multidrug-resistant pathogens are urgently needed for the treatment of these pathogens. We conducted an in vitro study on the activity of quinupristin/dalfopristin and other antibiotics against common clinical isolates of the gram-positive cocci, Haemophilus influenzae and Branhamella catarrhalis.


METHODS
The agar dilution method described by the National Committee for Clinical Laboratory Standards was used to determine the minimum inhibitory concentrations (MICs) of bacterial isolates from clinical specimens obtained from patients in a medical center.


RESULTS
All Staphylococcus aureus isolates were inhibited by quinupristin/dalfopristin (< or = 2 micrograms/ml). The MIC90s were 1 mg/ml for both methicillin-sensitive and -resistant S aureus. Quinupristin/dalfopristin inhibited streptococci at a concentration of 1 microgram/ml or less. The MIC90s were 1 microgram/ml for Streptococcus pneumoniae, S pyogenes and viridans streptococci. Ampicillin-resistant Enterococcus faecium was inhibited by quinupristin/dalfopristin at 0.5 to 4 micrograms/ml, with an MIC90 of 1 microgram/ml. H influenzae was inhibited by quinupristin/dalfopristin at 0.25 to 8 micrograms/ml, with an MIC90 of 4 micrograms/ml. B catarrhalis was inhibited by quinupristin/dalfopristin at 0.25 to 1 microgram/ml, with an MIC90 of 1 microgram/ml.


CONCLUSIONS
We found that quinupristin/dalfopristin showed good in vitro activity against staphylococci, streptococci and B catarrhalis but less in vitro activity against H influenzae.
Wang
F D
FD
Department of Medicine, Taipei Veterans General Hospital, Taiwan, ROC.
Lin
M L
ML
Liu
C Y
CY
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D006193:Haemophilus influenzae / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D001936:Moraxella catarrhalis / Q000187:drug effects*; D014769:Virginiamycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D014769:Virginiamycin; C062940:quinupristin-dalfopristin