Intravenous treatment of experimental Staphylococcus aureus endophthalmitis: imipenem versus the combination of ceftazidime and amikacin.
BACKGROUND
To compare the efficacy of intravenous (IV) imipenem (IPM) and a combination of IV ceftazidime (CAZ) and amikacin (AN) in the treatment of Staphylococcus aureus endophthalmitis in a rabbit model.


METHODS
Right eyes of 60 albino rabbits were injected with 1000 colony-forming units of S. aureus intravitreally. After 24 h, treatment with either IV IPM (37.5 mg/kg) every 8 h ( n=18) or IV CAZ (50 mg/kg) and AN (10 mg/kg) every 8 hours ( n=18) was begun and continued until the animals were killed at the indicated timepoints; 24 control animals received no treatment. The concentration of bacteria in the vitreous from six animals per group was determined microbiologically on days 2, 3, and 5 after infection, and histologic examination was performed on all eyes.


RESULTS
The number of eyes with positive cultures on day 5 was lower in the group that received IV IPM (2/6) compared with the IV CAZ/AN group (4/6) and the control group (6/6). For the culture-positive eyes, the bacterial concentrations were significantly lower for the IV IPM group compared with the IV CAZ/AN group on days 2 and 5 ( P<0.05 and P<0.0065, respectively), but not on day 3 ( P <0.8. Bacterial counts in both treatment groups were significantly lower than in the control group ( P<0.005). Eyes in all groups, however, showed severe intraocular inflammation.


CONCLUSIONS
IV IPM is more effective than is IV CAZ/AN in reducing the number of bacteria in an animal model of S.aureus endophthalmitis.
Engelbert
Michael
M
Department of Ophthalmology, Ludwig-Maximilians-Universität, Mathildenstrasse 8, 80336 Munich, Germany.
Miño de Kaspar
Herminia
H
Mette
Martina
M
Thiel
Martin
M
Ta
Christopher N
CN
Grasbon
Thomas
T
Schulze-Schwering
Markus
M
Klauss
Volker
V
Kampik
Anselm
A
D000583:Amikacin / Q000627:therapeutic use*; D000818:Animals; D002442:Ceftazidime / Q000627:therapeutic use*; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D004359:Drug Therapy, Combination / Q000627:therapeutic use*; D009877:Endophthalmitis / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D015818:Eye Infections, Bacterial / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D015378:Imipenem / Q000627:therapeutic use*; D007275:Injections, Intravenous; D011817:Rabbits; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D013211:Staphylococcus aureus / Q000302:isolation & purification / Q000502:physiology; D014822:Vitreous Body / Q000382:microbiology
D015378:Imipenem; D000583:Amikacin; D002442:Ceftazidime