Do infections provoke exacerbations and relapses of thrombotic thrombocytopenic purpura?

Several case reports have suggested an association between infections and thrombotic thrombocytopenic purpura (TTP). In Case 1, a 37-year-old female presented with TTP 6 times over 7 years, requiring 242 therapeutic plasma exchanges (TPE), for a per-course range of 4-57 TPE (median 48), and treatment durations of 4-241 days (median 71 days), largely on account of multiple exacerbations (range 0-3, median 3). Twelve of 17 (71%) of her presentations or exacerbations were associated with suspected infections, with confirmation in 9 episodes. These included pulmonary TB, CMV pneumonitis, mucocutaneous HSV, ventilator-associated or urinary tract-associated gram-negative sepsis, central line-associated staphylococcal bacteremia, and cellulitis. Except for TB, all infections occurred after splenectomy, which had been performed on day 33 of presentation 1. In Case 2, a 24-year-old female presented with TTP 3 times over 15 months. Her courses were managed with brief courses of TPE (5-11 treatments per course, median 5). Suppressed ADAMTS13 levels due to inhibitors were confirmed twice. Presentation 1 was antedated by atypical community acquired pneumonia. Presentation 3 (and possibly 2) followed prolonged, progressive, antibiotic-refractory periodontal infections ultimately requiring exodontic surgery. Our cases add to a literature that suggests that infection may be associated with exacerbations or relapses of TTP in some patients. Our patients demonstrated repeated TTP exacerbations in association with different infectious agents. A better understanding of the possible relationship between infection and clinical expression of TTP might lead to improved treatment decisions for patients with this complex illness.