Q fever endocarditis: over 14 years of surgical experience in a referral center for rickettsioses

BACKGROUND AND AIM OF THE STUDY: Q fever endocarditis caused by Coxiella burnetii is the most important etiology of negative blood culture endocarditis. Without specific clinical findings, diagnosis is difficult and prevalence of this life-threatening disease is underestimated. METHODS: Q fever endocarditis was assessed in 19 patients (15 men, four women; age range: 36-79 years) by evaluating clinical and echocardiographic criteria and specific serology. All patients had evidence of pre-existing valvular disease, and 10 had a valvular prosthesis. Diagnosis was assessed in: the presence of unexplained fever (n = 5), heart failure with valvular dysfunction (n = 10), hemolysis (n = 1), glomerulonephritis (n = 1) and stroke (n = 2). A late diagnosis was made in eight patients, either during or after surgery. RESULTS: In all cases, usual blood cultures remained negative, despite specific serology being positive. Transthoracic and transesophageal echocardiography were conclusive in only six cases (four vegetations, two periannular abscesses). Surgery was indicated in 15 patients for heart failure or valvular dysfunction (n = 12), hemolysis (n = 1) and periannular abscess (n = 2). Intraoperative findings were suggestive of endocarditis in seven cases; valvular cultures were positive in 92% of cases. All patients were treated with combined doxycycline/ hydrochloroquine or quinolone, for a mean of 24 months (range: 6-60 months). Mean follow up was 40 months (range: 6-144 months). Two patients died from heart failure, one patient was lost to follow up, and 16 patients had no late relapses. CONCLUSION: Q fever is an underestimated cause of endocardititis, and early diagnosis is the key to good prognosis. The need for systematic serologic examination in case of valvular dysfunction, with or without endocarditis symptoms, is emphasized.