Western blot analysis of immune response to Legionella bozemanii antigens.

The immune response to individual major antigens of Legionella bozemanii was studied in 67 sera from 26 inpatients with febrile disease using immunoblotting techniques. All the patients had fever of unknown origin and showed strong serological reactions to L bozemanii that cross-reacted with Rickettsia typhi, as determined by a standard indirect microimmunofluorescence assay. Sera analysed by western blotting reacted with 12-14 molecular components of L bozemanii with apparent molecular weights ranging from 14,000 to 94,000 daltons. These reactions compared well with a reference system using antisera of rabbits immunised with the same strain of Legionella. The three major cross-reactive components of R typhi were polypeptide antigens of 94,000, 67,000 and 43,000 daltons. It is concluded that western blotting can help in the differential diagnosis of patients with fever of unknown origin whose sera cross-react to L bozemanii and R typhi.

Legionella longbeachae pneumonia in a patient splenectomized for hairy-cell leukemia.

A 63-year-old man was admitted to the respiratory intensive care unit for pneumonia. Fifteen years earlier, hairy cell leukemia had been diagnosed and the patient underwent splenectomy. A clinical suspicion of legionellosis, later confirmed by both serology and isolation of the microorganism, prompted initiation of high dose erythromycin intravenously. The patient steadily deteriorated and passed away eight days later. This is the first reported case of hairy cell leukemia in which the diagnosis of Legionella longbeachae sero-group 1 infection was based on both serology and isolation.