Hemolytic uremic syndrome complicating Mycoplasma pneumoniae infection

Mycoplasma pneumoniae can cause various extrapulmonary manifestations but, to our knowledge, no case of Mycoplasma pneumoniae associated with hemolytic uremic syndrome (HUS) has been reported. We describe a 1-year-old boy with M. pneumoniae respiratory tract infection and associated microangiopathic hemolytic anemia, slightly decreased platelet count and mild renal impairment, suggesting a diagnosis of HUS. Assuming M. pneumoniae infection was the cause of HUS in this case, the different possible mechanisms, including an atypical HUS due to preexisting complement dysregulation, an alternative complement pathway activation induced by M. pneumoniae infection at the acute phase, an autoimmune disorder, and a direct role of the bacteria in inducing endothelial injury, are discussed. The signs of HUS resolved with treatment of the M. pneumoniae infection. Hemolytic uremic syndrome may be an unusual complication of M. pneumoniae infection.