Intracellular but not undetectable: A case of Francisella tularensis pericarditis.

Francisella tularensis is a facultatively intracellular, gram-negative bacillus and a rare cause of infection in the United States. We report a case of a 45-year-old male who presented with ongoing fever, shortness of breath, and was found to have a pericardial effusion and pulmonic infiltrates due to F. tularensis. Though tularemia is classically associated with rabbits and rodents, we note the patient in our case had no clear infectious exposure. Tularemia pericarditis is extremely rare, and this will be only the second report since 1957. We highlight the possible benefits of microbial cell-free DNA next generation sequencing when infection is suspected without obvious cause to reduce the morbidity and mortality from underlying infection.