Legionella-Induced Autoimmune Hemolytic Anemia: A Delayed and Unexpected Complication

Legionella pneumophilia is a multi-systemic disease primarily affecting the pulmonary, gastrointestinal, and to a lesser extent, renal systems. We present a case of Legionella pneumonia, which after resolution of respiratory compromise, was complicated by the development of autoimmune hemolytic anemia (AIHA) as determined by a positive Coombs test, and negative workup of other causes. Steroid immunosuppression was initiated, and red cell counts subsequently improved. While AIHA has only been anecdotally described in one prior case, the separation in time of the development and resolution of respiratory symptoms with the development of anemia most likely makes this an under-appreciated entity. An in vitro mechanism has been suggested; however in vivo causation has yet to be proven. Given the prolonged deleterious clinical consequences associated with the development of AIHA and the increase in recognition of Legionella outbreaks, greater recognition of this potential complication and research into the pathophysiology is warranted for the future.