Macroscopic haemoglobinuria associated with Mycoplasma pneumoniae infection successfully treated by clarithromycin.

A 25-year-old man developed macroscopic haemoglobinuria after a persistent dry cough. Although chest radiograph findings were normal, since the serum antibody for Mycoplasma pneumoniae was significantly elevated, a diagnosis infection with this organism was made. Despite the absence of apparent anaemia, a marked increase in serum haemolytic markers and positive result for urine haemoglobin indicated the haemolysis of red blood cells, which was likely to have occurred secondarily to M. pneumoniae infection. Shortly after the initiation of a macrolide antibiotic, clarithromycin, the patient's haemoglobinuria completely disappeared together with a complete resolution of his respiratory symptoms. In this case, due to the lymphocyte-stimulatory nature of M. pneumoniae, an enhanced immune response, such as the production of cold agglutinins, was likely to be involved in the pathogenesis of erythrocyte haemolysis. The immunomodulatory property of clarithromycin was thought to repress the increased immunological reaction and thus enable the resolution of the urine abnormality.