Background
Q fever is a zoonotic disease caused by the pathogen Coxiella burnetii. Farm animals and pets are the main source of infection and transmission to humans occurs via aerosolized inhalation. Clinical manifestations range from self-limited febrile illness to chronic infections lasting over 6 months. Once diagnosed by serologic testing, doxycycline is the treatment of choice with the addition of hydroxychloroquine in cases of endocarditis. Although less than 5% of patients with Q fever develop endocarditis, the incidence of endocarditis among patients with pre-existing valvular abnormalities ranges from 39-75%. Endocarditis is the most common chronic manifestation among other conditions including hepatomegaly, glomerulonephritis, and embolic phenomenon.
Case Description
57M with history of atrial fibrillation and bicuspid aortic valve stenosis s/p AVR with bioprosthetic valve in 2005, developed malaise, myalgia, and weight loss 6 months prior to developing night sweats, fever, and joint pain. The patient owns a mobile pet cleaning and grooming business, in which he partakes in cleaning the van and bathing tanks. Workup revealed leukocytosis with TTE demonstrating mitral and aortic valve vegetations as well as splenic abscesses and SMA thrombus, for which he underwent a splenectomy. He was started on doxycycline and plaquenil, with the addition of rifampin once testing with PCR+ and anti-phase 1&2 antibody titers confirmed Q fever endocarditis. The patient underwent a prophylactic median arcuate ligament release given SMA thrombus and celiac artery narrowing to avoid bowel ischemia complications prior to cardiac surgical intervention. He then underwent a redo sternotomy, AVR, MVR, aortic root debridement and replacement, with post-operative echo showing normal cardiac function with no evidence of residual vegetation. His post-operative course was complicated by right lower leg critical limb ischemia secondary to CFA thrombus, requiring a right CFA and popliteal artery embolectomy and four compartment fasciotomy. The patient also developed ventricular tachycardia requiring multiple shocks and vasoactive support, SBO, symptomatic cholecystitis requiring percutaneous cholecystostomy tube for drainage, and candida bacteremia.
Discussion
Q fever endocarditis is not often detectable in blood cultures; Hoen et al. observed negative blood cultures in 88 (14%) of 620 cases of infective endocarditis during a 1-year nationwide survey in France, 7 of which were caused by Q fever. Thus, it is imperative to perform serology testing when endocarditis is suspected, especially in individuals with prosthetic valves or history of valvular abnormalities. Patients with antiphospholipid syndrome are also at increased risk for developing endocarditis and persistent infections. Once diagnosed with Q fever, a 12 month treatment course of doxycycline has been shown to protect at-risk individuals with Q fever from developing endocarditis. Patients with chronic infection will require dual treatment with hydroxychloroquine for 18-24 months. Q fever endocarditis requires surgical replacement, however there is one reported case of successful conservative management with doxycycline monotherapy. Even after treatment, patients may experience post-Q fever fatigue syndrome, characterized by fatigue, nausea, arthralgias, and depression. Q fever endocarditis is a rare but life-threatening condition and prompt evaluation and treatment is imperative if Q fever is suspected, especially in patients with history of valvular abnormalities.
