Time-kill profiles of Enterococcus to antibiotics used for intravitreal therapy.
OBJECTIVE
To determine and then compare the time-kill profiles of Enterococcus to antibiotics used for intravitreal therapy.


METHODS
The time-kill profiles of four endophthalmitis isolates of Enterococcus faecalis, one vancomycin-resistant E. faecalis isolate, and three vancomycin-resistant isolates of E. faecium were determined against vancomycin, amikacin, cefazolin, gentamicin, ampicillin, ciprofloxacin, ceftazidime, clindamycin, and the combinations of vancomycin and amikacin, vancomycin and ceftazidime, vancomycin and gentamicin, vancomycin and ampicillin, cefazolin and gentamicin, and ampicillin and gentamicin.


RESULTS
No single antibiotic or combination was bactericidal (defined as 99.9% kill) to all isolates of Enterococcus. Gentamicin was bactericidal to all E. faecalis isolates. None of the tested antibiotics were bactericidal to vancomycin-resistant E. faecium.


CONCLUSIONS
The time-kill profiles demonstrated that vancomycin and ceftazidime did not produce a 99.9% kill for E. faecalis in this small study. Gentamicin combined with either cefazolin or ampicillin had somewhat better bactericidal activity and should be considered as an alternative therapy. Novel therapy may be necessary to treat endophthalmitis because of vancomycin-resistant Enterococcus, depending on the susceptibility patterns of the individual isolate and the response to initial therapy.
Kowalski
R P
RP
University of Pittsburgh, PA, USA.
Karenchak
L M
LM
Warren
B B
BB
Eller
A W
AW
D000900:Anti-Bacterial Agents; D015169:Colony Count, Microbial; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D009877:Endophthalmitis / Q000188:drug therapy / Q000382:microbiology; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D016984:Enterococcus faecium / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests; D014822:Vitreous Body / Q000187:drug effects
D000900:Anti-Bacterial Agents