Outbreaks of Legionnaires’ disease are well publicized and cases often make their way into court. Determining the source of exposure is a key factor in determining responsibility and involves many disciplines, including engineering, water treatment, epidemiology and microbiology. The microbiology of Legionella in the suspected environmental source is explored through examination of culture results. Ideally, the Legionella bacteria causing the infection is available from the patient for comparison to the Legionella isolated from the environment (water sources). If the source is identified, the patient and environmental strains match. There are a variety of methods that are used to make thislink and these will be reviewed. The role of microbiology in determining the source of infection will be discussed along with examples of cases and their outcomes from hotels and healthcare facilities. Microbiology plays an important role in resolution of case investigations.
