[Q fever endocarditis: a report of four cases and literature review].

Objective: To improve the diagnosis and treatment of Q fever endocarditis.
Methods: From 2008 to 2013, four cases of Q fever endocarditis were diagnosed in Peking Union Medical College Hospital. Clinical features, laboratory test, management and prognosis were analyzed with literature review.
Result: All four cases had long period of fever and heart murmur. Two patients represented with respiratory symptom and one with non-specific rash. General laboratory tests including complete blood cell count, ESR, C-reactive protein(CRP), liver function and radiology of lung did not show specific abnormalities. Signs of endocarditis were shown by ultrasound and important for diagnosis. Repeated blood culture was negative. All of the diagnoses were confirmed by serum antibody detection and the patients recovered well with treatment based on doxycycline or minocycline.
Conclusions: Endocarditis is the most common form of chronic Q fever, which is easily misdiagnosed because its blood culture is negative and may accompanied with varied manifestation such as pneumonia and liver injury. For the patients with chronic fever and blood culture negative endocarditis, chronic Q fever should be considered as differential diagnosis. The confirmatory method for diagnosis is serum antibody detection. Early and sufficient treatment may improve the prognosis.