HUS is uncommon among children admitted to our large urban children's hospital, accounting for only 29 admissions in the last 14 yrs (1983-1996). 8/29 (28%) had atypical HUS, and 6/8 presented with pneumonia/empyema. Of these 6 respiratory infection-associated HUS (resp+HUS), 5 presented during a 2.8 yr period from November, 1992-August, 1995. 4/6 had blood or pleural fluid cultures positive for S. pneumoniae, a rare cause of HUS. Resp+HUS patients did not differ in age, gender or ethnicity from those with typical, diarrhea positive HUS (D+HUS). All 6 with resp+HUS presented with respiratory distress, but only 2 had concomitant bloody stools. Admission hematocrit and Scr did not differ significantly between groups, but platelet nadir did (table). 5/6 resp+HUS had empyemas, requiring surgical drainage. 2/6 needed mechanical ventilation compared to no D+HUS. HUS was more severe in resp+HUS (table). No patient died or developed ESRD, but 1/6 has chronic renal failure compared to no D+HUS. 1/6 resp+HUS received FFP therapy, potentially complicating her course. Resp+HUS patients had pericarditis (1), pancreatitis (1), intussuception (1) and seizures (1). D+HUS had neurologic complications only (1/21). Epidemiology of our cluster of resp+HUS remains uncertain. No common source or type for S. pneumoniae was determined. No new resp+HUS case has been diagnosed in the past 16 months. Heightened awareness of the potential for clustered resp+HUS may help avoid FFP therapy, which is contraindicated in neuraminidase- mediated HUS, but not in other forms of HUS.

Table 1