Evidence of less severe aortic valve destruction after treatment of experimental staphylococcal endocarditis with vancomycin and dexamethasone

The beneficial effects of therapy combining an antibiotic and dexamethasone have been reported in human studies on meningitis and in experimental stud ies on septic arthritis, nephritis, and endophthalmitis. Since most patient s with staphylococcal endocarditis need a combination of medical and surgic al treatment, the purpose of this study was to determine whether the additi on of dexamethasone to vancomycin has any beneficial effect regarding the d egree of valve tissue damage or the course of experimental aortic valve end ocarditis caused by a methicillin-resistant strain of Staphylococcus aureus . Rabbits with catheter-induced aortic valve vegetations were randomly assi gned to a control group and to groups receiving dexamethasone (0.5 mg/kg of body weight, intravenously [i.v.], twice a day [b.i.d]), vancomycin (30 mg /kg, i.v., b.i.d), or dexamethasone plus vancomycin, for a total of 10 dose s (two doses per day for 5 days). The severity of valve tissue damage was s ignificantly less in groups receiving vancomycin plus dexamethasone compare d with that of the group receiving vancomycin alone (P < 0.001). The severi ty of tissue damage was inversely correlated with the mean polymorphonuclea r leukocyte number in valve tissue. No statistically significant difference s were observed between the vancomycin-treated group and the vancomycin-plu s-dexamethasone-treated group in survival, blood culture sterilization rate , or reduction of the microbial burden (in CFU per gram) in valvular tissue . In conclusion, treatment with a combination of vancomycin and dexamethaso ne for 5 days reduces the severity of valve tissue damage in experimental s taphylococcal aortic valve endocarditis. These findings could have signific ant implications in the treatment of staphylococcal endocarditis and deserv e further confirmation in clinical trials.