Q Fever Endocarditis: A Review of 135 Reported Cases

Abstract

Background: Q fever infection by Coxiella Burnetii was discovered in Australia in 1935. Q fever endocarditis is rare and usually affects patients with native valve abnormalities or those with valve replacements. Diagnosis is difficult as infection is often culture negative. We investigated reported cases of Q fever endocarditis in the literature from 1967 to 2017. Methods: A literature search for detailed case reports and case series of patients with Q fever endocarditis was performed. Papers were included if cases had positive PCR, valve culture or serology (antiphase IgG titre >1:800 or total complement fixation test total phase 1 antibodies of more than 512). A total of 31 studies from 15 countries were included. Results: The data show that 78% of patients were male with an average age of 51 years. Native valve abnormalities or the presence of prosthetic cardiac material was present in 84% of patients. Over 76% of patients had a documented history of significant contact with animals or travel. Only 6.5% cases demonstrated positive blood culture for Coxiella Burnetii with 99% of cases confirmed with serology. Doxycycline and Hydroxychloroquine was the most common antibiotic treatment regimen with an average length of treatment of 36 months, 71% of patients required surgery and 23 (17%) deaths were documented. Conclusions: Our study highlights the importance of serological diagnosis and possible risk factors such as the male gender, pre-existing valvular conditions including prosthetic cardiac material and contact with animals or travel.