Isolation of Francisella tularensis from blood

The isolation of Francisella tularensis from blood culture is extremely rare; a review of the literature produced only five documented cases. However, over a recent 17-month period we saw four cases of tularemia in which the organism was isolated in blood culture. The clinical presentations of our patients and those reported previously were very similar. Most of the patients had a significant underlying disease and presented with the typhoidal form of tularemia. Furthermore, all our patients had sepsis, pleuropulmonary disease, and rhabdomyolysis. Tularemia agglutinins were not performed on admission serum specimens or were nondiagnostic. All the F. tularensis isolates from blood culture in our series and most of the recent documented cases were obtained in radiometric blood culture systems, which may be more sensitive than conventional systems for detecting this fastidious microorganism.