Legionella micdadei prosthetic valve endocarditis complicated by brain abscess: case report and review of the literature

Legionella endocarditis is extremely uncommon, and embolic phenomena have never been reported. We report the first case of Legionella micdadei prosthetic valve endocarditis complicated by brain abscess. A 57-y-old immunocompromised woman with a history of mitral valve replacement developed confusion and left-sided weakness. Brain magnetic resonance imaging showed a 3-cm peripheral-enhancing mass. Transoesophageal echocardiography suggested a perivalvular abscess. Blood cultures and valve cultures were negative. She was diagnosed with 16S rRNA polymerase chain reaction and silver stain, and was discharged with levofloxacin after a redo mitral valve replacement. Twelve cases of Legionella endocarditis were reviewed. Only one case had a native valve, and her endocarditis occurred after pneumonia. All cases were cured. The duration of antibiotic therapy was variable. Legionella species should be considered in the differential diagnosis of culture-negative endocarditis in both immunocompetent and immunocompromised patients. Molecular techniques and silver impregnation stains are useful, especially when cultures using buffered charcoal-yeast extract agar are negative.