MORPHOLOGY OF LEGIONNAIRES DISEASE ORGANISM

Abstract

The Pennsylvania [USA] Department of Health, Bureau of Laboratories, isolated the Legionnaires'' disease organism from 2 patients with Legionnaries'' disease proved by serologic techniques. The morphology which the isolate assumes in yolk sac tissue and on bacteriologic media was studied. The organism was Gimenez-positive and gram-variable. Using an indirect immunofluorescent procedure, it was shown to react with convalescent serum samples taken from patients who had Legionnaires'' disease. The organism multiplies by binary fission extracellularly and intracellularly; is coccoid and bacillary in form; and contains characteristic cytoplasm, nucleoids, a cytoplasmic membrane, and a small cell wall of variable size. It may produce spores of unusual appearance. Intracellular replication characteristically occurs within vacuoles. The Legionnaires'' disease organism conforms to the morphologic criteria for a prokaryocyte.