Infectious diseases as a trigger in thrombotic microangiopathies in intensive care unit (ICU) patients?

Objective: Thrombotic microangiopathy (TMA) has been associated with a large number of underlying diseases. We conducted a descriptive, retrospective study including all TMA adult patients admitted to our ICU, with a particular interest in infectious episodes as a trigger of TMA. Patients: All adult patients (30) with a diagnosis of TMA admitted to the medical ICU at Saint-Louis Hospital (Paris, France) between 1992 and 1998 were retrospectively included. Methods: All patients with clinical and microbiological evidence of bacterial infection were treated with intravenous antibiotics. The specific treatment of TMA consisted in solvent/detergent-treated plasma administration by plasma exchange or high volume plasma infusion (30 ml/kg per day) in fractionated doses. Results: Among the 30 adult patients studied, TMA in 16 (53%) was associated with microbiologically documented infection. An acute infection was found in 8/9 patients with an HIV-related TMA, in 2/6 patients with a systemic lupus erythematosus (SLE)-related TMA and in 3/6 patients with TMA associated with other disorders. In three patients, an acute infectious disease was the only cause associated with the TMA. Four other patients had clinical manifestations suggesting an infection process but without bacteriological documentation. Escherichia coli was isolated in 7/16 cases and verotoxin was found in the stools of two other patients. All patients were treated with plasma administration and those with evidence of infection were systematically and intensively treated with antibiotics. Eventually 8 patients died (27%), 20 (67%) reached complete remission and 2 partial remission. Conclusion: Bacterial infections are commonly observed amongst TMA patients hospitalized in ICUs and may act as a trigger of this disease. Screening for infection is a requirement in patients with TMA, either idiopathic or associated with other conditions.