OUTBREAK OF LEGIONNAIRES-DISEASE LINKED TO A DECORATIVE FOUNTAIN BY MOLECULAR EPIDEMIOLOGY

The incubation period of Legionnaires' disease in five patients was tr aced to attendance at conventions in a hotel in the Orlando, Florida, area between January 6 and February 2, 1992. The five case patients (m ean age, 69 years) were older than 55 randomly chosen controls (mean a ge, 53 years) who had also attended one of the same conventions (p = 0 .007). All case patients were males, as were 40% of the controls (p = 0.01). No significant differences in exposures were found between case patients and controls, but all case patients and 65% of the controls reported exposure to a decorative fountain in the hotel lobby. Water f rom the fountain was the only one of 55 environmental specimens to tes t positive for Legionella. Both the environmental isolate and the only clinical isolate were Legionella pneumophila serogroup 1, with identi cal patterns identified on monoclonal antibody subtyping and pulsed-fi eld gel electrophoresis (PFGE) of genomic restriction fragments. The f ountain's recirculating system had been irregularly maintained, and wa ter in the fountain may have been heated by submersed lighting. These findings demonstrate the utility of monoclonal antibody subtyping and PFGE of genomic restriction fragments in assessing the significance of environmental isolates of L. pneumophila, especially when other epide miologic findings are inconclusive. They also show that decorative fou ntains may be a potential source of infection with L. pneumophila, and emphasize the need for standard maintenance and disinfection procedur es.