Comparative intravitreal antibiotic therapy for experimental Enterococcus faecalis endophthalmitis.
OBJECTIVE
To evaluate the most effective intravitreal antibiotic treatment of vancomycin-sensitive and -resistant Enterococcus faecalis endophthalmitis.


METHODS
Animal experiment.


METHODS
Seventy-eight New Zealand white rabbits received an intravitreal injection of 10(5) vancomycin-sensitive or -resistant E faecalis organisms in one eye. Infections were allowed to proceed 3 hours before dividing animals randomly into the following treatment groups (n = 6, each): the vancomycin-sensitive E faecalis model--(1) vancomycin (1 mg/0.1 mL), (2) combined vancomycin (1 mg/0.1 mL) and amikacin (0.4 mg/0.1 mL), (3) combined vancomycin (1 mg/0.1 mL) and gentamicin (0.1 mg/0.1 mL), (4) combined vancomycin (1 mg/0.1 mL) and ceftazidime (2 mg/0.1 mL), (5) combined ampicillin (5 mg/0.1 mL) and gentamicin (0.1 mg/0.1 mL), and (6) pristinamycin (1 mg/0.1 mL); and the vancomycin-resistant E faecalis model--(1)same as above, excluding group 4. Control groups received sterile balanced salt solution. Twenty-four hours following intravitreal treatment, vitreous humor was collected for quantitative bacteriological studies.


RESULTS
Intravitreal therapy with combined vancomycin and amikacin provided the most effective reduction of vancomycin-sensitive E faecalis organisms compared with combined vancomycin and gentamicin therapy (P =.10, Wilcoxon's rank sum test) or any other treatment group (P < .01, Wilcoxon's rank sum test). For vancomycin-resistant E faecalis endophthalmitis model, the combined ampicillin and gentamicin therapy was the most effective, followed by the combined vancomycin and amikacin therapy (P < .01, Wilcoxon's rank sum test).


CONCLUSIONS
Treatment with intravitreal vancomycin plus amikacin and with intravitreal ampicillin plus gentamicin provide an effective bactericidal therapy for severe experimental vancomycin-sensitive and -resistant E faecalis endophthalmitis, respectively.
Ocular Microbiology Laboratory, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
S
S
Choi
T W
TW
Hahn
G
G
Osterhout
T P
TP
O'Brien
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D004341:Drug Evaluation; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination; D009877:Endophthalmitis / Q000188:drug therapy* / Q000382:microbiology; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000302:isolation & purification; D015818:Eye Infections, Bacterial / Q000188:drug therapy*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy*; D007267:Injections; D008826:Microbial Sensitivity Tests; D009883:Ophthalmic Solutions; D011817:Rabbits; D014822:Vitreous Body / Q000382:microbiology
D000900:Anti-Bacterial Agents; D009883:Ophthalmic Solutions