REINFECTION WITH LEGIONELLA-PNEUMOPHILA DOCUMENTED BY PULSED-FIELD GEL-ELECTROPHORESIS

A 50-year-old man with chronic lymphocytic leukemia experienced two ep isodes of community-acquired legionnaires' disease. For determining wh ether this was the result of relapse or reinfection, Legionella pneumo phila strains, cultured from sputum specimens and his home water suppl y, were characterized by pulsed-field gel electrophoresis. Analysis of the restriction patterns and the clinical data indicated that the sec ond disease period was most likely the result of reinfection. We concl ude that after diagnosis of community-acquired legionnaires' disease i n an immunocompromised patient, culturing of the domestic water suppli es for L. pneumophila should be considered; if such cultures are posit ive, adequate measures to prevent reexposure have to be taken.