Legionella pneumophila and water temperatures in Australian hospitals.

Thirty-four samples of warm waters from 12 psychiatric centres in Victoria and New South Wales were examined for legionellae by guinea-pig inoculation. Legionella pneumophila was isolated from 20 of the samples collected from ten of the establishments investigated. The detected prevalence proportion of L. pneumophila in waters of temperatures 36 to 43 degrees C was 0.9 (18/20), whereas the prevalence in waters of temperatures 45 to 54.2 degrees C was 0.14 (2/14). The two 'positive' waters within the latter range showed evidence of low numbers of L. pneumophila. No significant antibody titres to relevant serogroups were detected in the 112 exposed residents tested from seven psychiatric hospitals in New South Wales. The findings show that the temperature range with the greatest prevalence of L. pneumophila in warm waters is 36 to 43 degrees C. The presence of legionellae in these warm water-distribution systems contrasts with their absence from the water-distribution systems of Victorian hospitals in an earlier survey and underlines the value and simplicity of the usual Australian practice of maintaining hospital hot water temperatures at about 70 degrees C in the control of L. pneumophila.