Pericardial effusion as the only manifestation of infection with Francisella tularensis: a case report

INTRODUCTION Francisella tularensis, a facultative intracellular Gram-negative bacterium, has rarely been reported as an agent of pericarditis, generally described as a complication of tularemia sepsis. F. tularensis is a fastidious organism that grows poorly on standard culture media and diagnosis is usually based on serological tests. However, cross-reactions may occur. Western blotting allows the correct diagnosis. CASE PRESENTATION A non-smoking 53-year-old woman was admitted to hospital with a large posterior pericardial effusion. Serological tests showed a seroconversion in antibody titers to F. tularensis (IgG titer = 400) and Legionella pneumophila (IgG titer = 512). F. tularensis was identified by Western immunoblotting following cross-adsorption. The patient reported close contact with rabbits 2 weeks prior to the beginning of symptoms of pericarditis. CONCLUSION We report a rare case of pericardial effusion as the only manifestation of infection by F. tularensis. The etiological diagnosis is based on serology. Western blotting and cross-adsorption allow differential diagnosis.