Introduction
Infective endocarditis (IE) is a serious diagnosis that occurs around 30 new cases per million worldwide, it is a challenging condition that requires the most attention for early diagnosis and proper treatment [1-3]. IE can occur following valvular problems and other heart surgeries and devices and leads to fatal cardiac and non-cardiac manifestations. Due to the multi-organ damages caused by IE, early detection with laboratory examinations, transesophageal echocardiography (TEE), imaging, and cultures are required and definite treatment with antibiotics or even surgery is critical [4-6]. One of the difficulties in IE diagnosis is blood culture-negative endocarditis (BCNE). Although BCNE is decreased due to advanced diagnostic methods, it is responsible for approximately 20% of infective endocarditis [7, 8]. Based on documented evidence, the organisms responsible for BCNE are mostly Bartonella, Coxiella, and Chlamydia species [7, 9]. among these organisms Bartonella species are responsible for the most number of BCNE in recent years [10].
Q fever is a zoonotic endemic disease caused by Coxiella burnetiiwhich can cause BCNE in patients who underwent valvular surgeries and other chronic heart problems. Patients having Q fever are commonly asymptomatic, while others have different non-specific symptoms; therefore, its diagnosis depends on the patient’s history of animal contact especially in endemic regions [11, 12].
Based on different surveys, Iran is one of the regions with C. burnetii endemicity, and due to the broad contact with domestic animals, Q fever has a high prevalence in our region; therefore, we should consider this domestic disease as a probable cause of BCNE [13, 14]. In this case report, we are presenting a patient with Q fever endocarditis with a history of chronic endocarditis and multiple valve replacement.