Introduction: Prosthetic valve endocarditis (PVE) re-presents a therapeutic challenge. Management strategy is established by guidelines and consists in combina-tions of bactericidal wide spectrum antibiotics over a long period with the purpose to cure infection. Surgery may be associated if and when is needed.

Objective: To analyze if other combination of antibio-tics than those established by guidelines may cure cul-ture negative prosthetic valve endocarditis.

Methods: We performed an retrospective analysis of 126 patient with infective endocarditis admitted betwe-en 2000-2004, out of which we selected 56, age 54.64 34 years old, 64% men, with infected valve pros-thesis: mechanic (86%) or biological (14%). They were divided in early (E=29) and late PVE (L=27). Analyzed variables were etiology, peripheral site of infection, biological, echocardiography and clinical parameters, demography, evolution, complications, valve surgery if needed. Lost to follow up patients were excluded. An-tibiotic strategy was adapted by infectious disease spe-cialist according to patients characteristics (evolution, duration and type: carbapenems, glycopeptides, ami-noglycosides and rifampicin).

Results: In studied patiens PVE type was independent of prosthesis position. Late PVE was more frequent on biological (p=0.0015) and early PVE on mechanical prosthesis. Previous endocarditis induced a high risk of PVE. The peripheral site of infection was related to etiology: S aureus with skin infections (p=0.000002), Viridans Streptococci with teeth/oral infections (p=0.00026), Group D Streptococci with digestive ones (p=0.000000). Cultures number per patient: 5.46 obtained/ 2.15 positive in early PVE, 5.46 obtained / 2 positive in late PVE. PVE etiology was as following: ne-gative cultures~52%, Coagulase-positive staphylococci 9%, Coagulase-negative staphylococci 16%, Viridans Streptococci 5.4%, Group D Streptococci 7.15%, Gram negative bacilli 5.36%. The number of antibiotics com-binations per patient was 1.51 with changes determi-ned by intolerance or lack of efficacy to induce afebri-lity. Valve surgery was performed due to complications: embolism, persistent fever, perivalvular extension of infection with heart failure aggravation. Perioperative mortality was ~33%. Total duration of antibiotics cure with or without surgery was 33.55 ± 12.8 days.

Conclusions: Antibiotic treatment, irrespective of eti-ology and of the type of antibiotic combinations ge-nerated the cure of infections in 71% of patients with conservative therapy and in 90.4% of patients when surgery was associated. The duration to fever remission was shorter when carbapenems+ aminoglycosides were used, irrespective of etiology but they did not change the outcome pattern. The outcome of patients under carbapenems+ glycopeptides was better, with very few complications. Changes in antibiotic regimens were frequent in order to increase tolerability over the cure duration. Alternatives to those regimen recommended by guidelines may be safe and effective even when the rate of culture negative PVE is high.