Legionella pneumophila is being increasingly recognized as a common pathogen causing both community-acquired and nosocomial pneumonia that is responsible for significant morbidity and mortality. It is also one of the most common aetiology discovered when pneumonia is sufficiently severe to require admission to an intensive care unit. It's likely to cause a severe form of pneumonia with high likelihood of adverse medical outcomes which includes rapid deterioration, respiratory failure and the need for intensive care unit (ICU) admission.