TIME-KILL PROFILES OF ENTEROCOCCUS TO ANTIBIOTICS USED FOR INTRAVITREAL THERAPY

BACKGROUND AND OBJECTIVE: To determine and then compare the time-kill profiles of Enterococcus to antibiotics used for intravitreal therapy. PATIENTS AND METHODS: The time-kill profiles of four endophthalmitis isolates of Enterococcus faecalis, one vancomycin-resistant E. faecali s isolate, and three vancomycin-resistant isolates of E. faecium were determined against vancomycin, amikacin, cefazolin, gentamicin, ampici llin, ciprofloxacin, ceftazidime, clindamycin, and the combinations of vancomycin and amikacin, vancomycin and ceftazidime, vancomycin and g entamicin, vancomycin and ampicillin, cefazolin and gentamicin, and am picillin and gentamicin. was bactericidal (defined as a 99.9% kill) to all isolates of Enterococcus. Gentamicin was bactericidal to all E. f aecalis isolates. None of the tested antibiotics were bactericidal to vancomycin-resistant E. faecalis CONCLUSIONS: The time-kill profiles d emonstrated that vancomycin and ceftazidime did not produce a 99.9% ki ll for E. faecalis in this small study. Gentamicin combined with eithe r cefazolin or ampicillin had somewhat better bactericidal activity an d should be considered as an alternative therapy. Novel therapy may be necessary to treat endophthalmitis because of vancomycin-resistant En terococcus, depending on the susceptibility patterns of the individual isolate and the response to initial therapy.