LEGIONELLA-PNEUMOPHILA CONTAMINATION OF A HOSPITAL HUMIDIFIER - DEMONSTRATION OF AEROSOL TRANSMISSION AND SUBSEQUENT SUBCLINICAL INFECTION IN EXPOSED GUINEA-PIGS

Abstract
Water from a humidifier located in a hospital was contaminated with L. pneumophila, serogroup 1. The source of water for the humidifier was the hospital potable water system. Exposure of culture mediums to the humidifier aerosols yielded L. pneumophila, serogroup 1. Exposure of guinea pigs to humidifier aerosols produced a subclinical infection as demonstrated by seroconversion to L. pneumophila. Seroconversion rate of guinea pigs to L. pneumophila was higher when greater quantities of L. pneumophila were present in the water; a corresponding increase in recovery of the organism from culture mediums exposed to aerosols was also seen. Thus, mechanically created aerosols of Legionella-contaminated potable water might be the transmission vehicle of Legionnaires'' disease, especially in the hosptial setting.