THROMBOTIC THROMBOCYTOPENIC PURPURA THAT IS REFRACTORY TO THERAPEUTICPLASMA-EXCHANGE IN 2 PATIENTS WITH OCCULT INFECTION

BACKGROUND: The etiology of thrombotic thrombocytopenic purpura (TTP) remains undetermined. TTP has been associated with a number of seconda ry causes including infections, drugs, menses, pregnancy, autoimmune d iseases, and bone marrow transplantation. Regardless of the inciting f actors, it is widely accepted that endothelial injury and platelet agg regation are integral components. The morbidity and mortality have bee n significantly reduced with the use of plasmapheresis. However, refra ctory forms of TTP remain a clinical management challenge. Refractory TTP has not previously been associated with occult bacterial infection . CASE REPORT: Two patients had classic TTP that was refractory to dai ly plasma exchange with fresh-frozen plasma. Multiple attempts over a period of months to wean these patients off plasma exchange resulted i n exacerbations of disease activity, as indicated by increased schisto cytosis, decreased hematocrit, increased serum lactate dehydrogenase, and decreased platelet counts. Both patients were empirically treated for infections during hospitalization, although microbial cultures fai led to isolate an organism. Discontinuation of antimicrobial therapy o n multiple occasions in one patient was associated with recurrence of disease. In the other patient, dental extraction with drainage of an o ccult periodontal abscess resulted in sustained remission of disease. CONCLUSION: Occult bacterial infection may play a role in triggering a nd sustaining TTP that is refractory to conventional treatment. A care ful search for such an infection and appropriate antimicrobial therapy should be considered in the management of these patients.