Legionnaires' disease in South Australia. Four case reports

Legionnaires' disease in South Australia, 1979-1988

Laboratory investigations supported the diagnosis of legionella pneumonia in 108 patients in South Australia over the past 10 years. Legionella pneumophila was responsible for 91 infections: the serogroup-1 strain caused 81 of these. L. pneumophila serogroup 2 was the only other strain of L. pneumophila that was isolated from patients; it caused infection in eight patients. In two patients, the serological results did not distinguish between infection with L. pneumophila serogroup 1 and serogroup 2. Legionella longbeachae serogroup 1 accounted for the remaining 17 infections. Serological tests were used to make the diagnoses in 77 cases. Legionella spp. were isolated from 24 patients and were identified in the respiratory-tract secretions of a further seven cases by direct immunofluorescence microscopy. L. longbeachae serogroup 1 first was isolated from a patient with pneumonia in South Australia in May, 1987. Since then it has been isolated from specimens from six other patients. No evidence exists for a common-source outbreak of L. longbeachae but an outbreak of Legionnaires' disease that was caused by L. pneumophila serogroup 1 occurred in South Australia in 1986.

Legionnaires' disease in a renal transplant recipient

A case of fatal Legionnaires' disease in an immunosuppressed renal transplant recipient is reported. Diagnosis was based on the antemortem culture of Legionella pneumophila from sputum and pleural aspirate.

Legionnaires' disease in South Australia. Prevalence and diagnosis

Legionella pneumophila was successfully isolated from sputum, and from respiratory secretions obtained by tracheal aspiration, of two patients with Legionnaires' disease by means of guinea pigs and charcoal yeast extract agar. Direct culture of lung tissue from one of these patients gave a pure growth of L. pneumophila. In both cases, legionellas were isolated from specimens which were collected several days after treatment with erythromycin began. Direct fluorescent antibody tests on these specimens gave positive results. This test can result in the rapid diagnosis of legionellosis in carefully selected patients. Serological diagnosis by demonstrating a greater than fourfold rise in antibody level, particularly that of IgM antibody, is the method of choice for making the diagnosis of legionellosis in patients who do not have life-threatening infections or in whom a definitive bacteriological diagnosis cannot be made. Serological studies suggest that infection with L. pneumophila is endemic in South Australia.