Falsecolour scanning electron micrograph of the Gram negative bacterium Legionella pneumophila cause of Legionnaires disease The bacterium was identified as an agent of disease in after a mysterious outbreak of pneumonia other respiratory illness at an American Legion convention in the USA It was found living in watertanks shower heads in the cooling towers of airconditioning systems The disease is also known as legionellosis Magnification x at x cm size
