The fluoroquinolones exert a reduced rate of kill against Enterococcus faecalis.
The bactericidal activities of ciprofloxacin, ofloxacin and DR-3355 have been investigated against Enterococcus faecalis, Staphylococcus aureus and Staphylococcus epidermidis over 24 h. The three fluoroquinolones were found to be rapidly bactericidal against the staphylococci, killing over 99% of the bacteria during the first 3 h of exposure with a further reduction in viability of approximately one logarithm occurring over the next 21 h. In contrast, the fluoroquinolones displayed a much slower rate of kill against E. faecalis, as little or no bactericidal activity was detected over the first 3 h for both E. faecalis ATCC19433 and a clinical isolate. At 6 h all three of the drugs were bactericidal against the enterococci although the amount of kill was not as great as against the staphylococci. However, at 24 h the amount of kill obtained with all three drugs was similar to that obtained for staphylococci exposed to these drugs. Ciprofloxacin, ofloxacin and DR-3355 were not active against E. faecalis ATCC19433 in phosphate buffered saline and therefore require cell division for their bactericidal activity against this species.
Lewin
C S
CS
Department of Medical Microbiology, University of Edinburgh Medical School, UK.
Morrissey
I
I
Smith
J T
JT
D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D013293:Enterococcus faecalis / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects
D000890:Anti-Infective Agents; D002939:Ciprofloxacin; D015242:Ofloxacin