Disorders extrinsic to the red blood cell Causes of disorders extrinsic to the RBC include Drugs (eg, quinine, quinidine, penicillins, methyldopa, ticlopidine, clopidogrel) Immunologic abnormalities (eg, autoimmune hemolytic anemia, thrombotic thrombocytopenic purpura) Infections Mechanical injury (microangiopathic hemolytic anemia, eg, prosthetic heart valve) Reticuloendothelial hyperactivity (hypersplenism) Toxins (eg, lead, copper) Infectious organisms may cause hemolytic anemia through the following mechanisms: Direct action of toxins (eg, Clostridium perfringens, alpha - or beta-hemolytic streptococci, meningococci) Invasion and destruction of the RBC by the organism (eg, Plasmodium species, Bartonella species, Babesia species) Antibody production (eg, Epstein-Barr virus, mycoplasma).