Nosocomial Legionnaires' disease in Columbus, Ohio.

Three patients with severe pneumonia at a community hospital in Columbus, Ohio, were found to have Legionnaires' disease in late August 1977. A subsequent serologic survey of patients with pneumonia at this hospital identified three additional cases. Among patients with pneumonia, hospital exposure in the 2 weeks before onset of illness was significantly associated with Legionnaires' disease (P = 0.003). Serosurveys of hospital employees with a recent history of upper respiratory illness, healthy employees, and workers at the hospital construction site showed that one of 101, one of 107, and none of 114, respectively, has a single reciprocal titer of greater than or equal to 256 to the Legionnaires' disease (LD) bacterium. Serosurveys of patients with pneumonia at three control hospitals identified five additional patients with Legionnaires' disease, three of them with pneumonia that was apparently hospital acquired in a single renal transplant unit. A fourth patient from that unit without clinical illness had a fourfold rise in titer to LD bacterium.