Snapshot A 50-year-old man presents to the emergency room for prolonged fever, shortness of breath, and chest pain. He is admitted for heart failure and suspected endocarditis. A cardiac echocardiogram shows vegetation on the valves. The initial blood cultures are negative. Upon further investigation, he works at a leather supplier and often visits farms to evaluate the cattle. He is treated for a suspected zoonotic endocarditis with doxycycline and hydrochloroquine. Introduction Classification Coxiella burnetii obligate intracellular gram-negative bacteria Legionellales order causes Q fever and culture-negative bacterial endocarditis transmitted from farm animals (sheep, goat, and cattle amniotic fluid) via inhalation of aerosolized spores even at low doses no arthropod vector Prevention Q fever vaccine is available in Australia for those with high occupational risk Epidemiology Incidence found worldwide Risk factors exposure to farm animals occupational exposure to animal products (e.g., animal hides) immunosuppression ETIOLOGY Pathogenesis C. burnetii is able to replicate in phagocytic vacuoles in low pH environments can survive oxidative and osmotic stress can survive in the environment for years Presentation Symptoms fever and headaches chronic infection weight loss night sweats acute infection pneumonia cough sore throat Physical exam acute infection pneumonia rhonchi on lung exam shortness of breath chronic infection endocarditis heart failure shortness of breath vascular infection abdominal pain infected aneurysm vascular rupture osteomyelitis tenosynovitis tenderness at the site of infection hepatitis jaundice Imaging Chest radiography indication suspected pneumonia from acute Q fever findings lobar opacities or patchy infiltrates Echocardiography indication suspected endocarditis from chronic Q fever findings vegetation on valves, most commonly mitral valve Studies Labs blood cultures are usually negative transaminitis elevated erythrocyte sedimentation rate or C-reactive protein confirmatory testing detection of immunoglobulin G (IgG) on serology detection of DNA on polymerase chain reaction Making the diagnosis based on clinical presentation and laboratory studies suspect Q fever in cases of culture-negative endocarditis Differential Tularemia distinguishing factor typically presents with a maculopapular rash that may ulcerate Bacterial endocarditis distinguishing factors blood cultures are usually positive other culture-negative endocarditis to consider are Bartonella spp HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella) Treatment Medical doxycycline indication all patients hydroxychloroquine indication chronic Q fever given with doxycycline trimethoprim/sulfamethoxazole indication for pregnant women outcome may reduce fetal death Complications Adverse fetal outcomes in pregnant women Prognosis May have prolonged course if untreated Most cases resolve with treatment