EVALUATION OF THERAPEUTIC MEASURES FOR TREATING ENDOPHTHALMITIS CAUSED BY ISOGENIC TOXIN-PRODUCING AND TOXIN-NONPRODUCING ENTEROCOCCUS-FAECALIS STRAINS
Bd. Jett et al., EVALUATION OF THERAPEUTIC MEASURES FOR TREATING ENDOPHTHALMITIS CAUSED BY ISOGENIC TOXIN-PRODUCING AND TOXIN-NONPRODUCING ENTEROCOCCUS-FAECALIS STRAINS, Investigative ophthalmology & visual science, 36(1), 1995, pp. 9-15
Purpose. Management of endophthalmitis typically includes antibiotic c
ombinations to arrest bacterial growth and antiinflammatory agents to
limit inflammatory damage to sensitive tissues. Little research has be
en reported that systematically evaluates the contribution of each the
rapeutic component for treating infections caused by organisms of vary
ing virulence. The authors determined the relative value of the antiin
flammatory corticosteroid, dexamethasone, as an intravitreal therapeut
ic adjunct for the treatment of infection caused by either Enterococcu
s faecalis expressing a cytolytic toxin preciously shown to contribute
to the course and severity of infection, or an otherwise identical st
rain of E. faecalis specifically attenuated in expression of the cytol
ytic toxin. Methods. Endophthalmitis in rabbits was monitored using el
ectroretinography (ERG). Eyes were infected with 100 colony forming un
its of either the cytolytic or the noncytolytic E. faecalis strain, In
travitreal ampicillin and gentamicin were administered at postinfectio
n dq 1, and intravitreal dexamethasone was either omitted or administe
red at day -1, 1, or 1.5. Results. ERG B-wave amplitude declined preci
pitously throughout the course of infection with cytolytic toxin-produ
cing E, faecalis, despite the administration of antibiotics and regard
less of the time of dexamethasone administration. In fact, the ultimat
e course of infection caused by cytolytic E. faecalis did not differ f
rom the course in untreated controls. In contrast, infections caused b
y specifically attenuated, noncytolytic strains of E. faecalis respond
ed well to antibiotics augmented by antiinflammatory therapy when the
latter was administered either 1 or 1.5 days after the initiation of i
nfection. In these cases, no loss in ERG B-wave response was observed.
Conclusions. These results underscore the importance of bacterial tox
ins in infectious diseases of the eye and their contribution to treatm
ent failures. These results further suggest that in cases of endophtha
lmitis caused by toxin producing bacteria, significant improvement in
clinical outcome win require specific therapeutic targeting of the tox
ins involved.