Background: Endocarditis is an infection of the endocardial layer of the heart known as fatal infection. Gold standard diagnosis of infectious endocarditis is blood culture, which in some cases can be negative. In blood culture-negative endocarditis, the early diagnosis, and treatment are much harder, which can increase morbidities and also mortality. Case presentation: In this case report we are presenting a patient with intermittent fever for three months with a history of aortic and pulmonary valve replacement and also recurrent blood culture-negative endocarditis. According to the pandemic situation, we checked the Covid-19 PCR and also performed a chest computed tomography (CT) -scan, which both were negative and did not represent any pathologic conditions. Other examinations such as transesophageal echocardiography (TEE) and blood cultures were all normal and the only abnormal finding we had was a positron emission tomography (PET) - CT scan with endocarditis and sternum osteomyelitis evidence. Conclusion: After several evaluations based on endemic epidemiology, the Real-time PCR and IFA (IgG phase I; 1:16384, IgG phase II; 1:16384) were positive for Q fever and the patient responded to the proper doxycycline and hydroxychloroquine treatment.

In this case report, we are presenting a man with intermittent fever for three months with a history of aortic and pulmonary valve replacement and also recurrent blood culture-negative endocarditis. After several evaluations based on endemic epidemiology, the Real-time PCR and IFA (indirect immunofluorescence assay) were positive for Q fever.