Coxiella burnetii endocarditis: Long term follow up of 20 patients

Introduction and objectives. Coxiella burnetii is a causative agent of incr easingly frequent subacute infective endocarditis, and is associated with e levated morbimortality. Our aim in the present study was to assess the clin ical, serological and therapeutic long-term evolution of 20 patients with C oxiella burnetii endocarditis. Methods. Twenty patients (13 male and 7 female, age 42 +/- 10 years) admitt ed between 1982 and 1996 were retrospectively studied. All of them fulfille d the Duke criteria modified by Raoult for Q fever endocarditis. Results. Endocarditis involved prosthetic and native valves in 14 and 6 pat ients, respectively. All patients except one received antibiotic treatment. Patients treated with doxycycline in monotherapy showed worse evolution th an those treated with doxycycline in combination with other antibiotics. Va lve replacement was performed in 15 patients, due to prosthetic dysfunction in most of them. The overall mortality was 40% (8 patients). At follow-up of 74 months (range 19-156) (mean 74 +/- 47) all patients showed persistent high levels of phase I antibodies. At follow-up of 15 to 65 months (32 +/- 30) antibiotic treatment was suspended in five patients because they were asymptomatic and without microbiologic findings of valvular endocarditis. Conclusions. Q fever endocarditis was associated with severe complications, which often required valve replacement. All patients showed persistent hig h serological titers of Coxiella burnetii endocarditis without other signs of active infection. This finding raises the issue of suspending antibiotic treatment in patients with negative microbiologic findings and questions t he persistence of abnormal serology as a monitor of treatment efficacy.