Legionella is a major cause of both pneumonia and an acute self-limiting febrile disease called Pontiac Fever. A standard procedure for the isolation, culture, and identification of Legionella has been detailed in ISO 11731. Legionella Acid Buffer is a reagent commonly used according to ISO 11731 for microbiological testing, particularly in the selective isolation of Legionella species, which are pathogenic bacteria responsible for Legionnaires' disease. The buffer facilitates Legionella isolation through below mechanisms. • Selective Inhibition: The acidic pH of the buffer (usually around 2.2) helps suppress the growth of competing microorganisms that cannot tolerate such conditions, while Legionella species, which can withstand acidic environments, are unaffected. • Diagnostic Utility: The acid treatment is typically applied to clinical or environmental samples before culturing on specialized media like Buffered Charcoal Yeast Extract (BCYE) agar to enhance the recovery of Legionella. Legionella Acid Buffer is particularly useful in diagnostic laboratories during the process of detecting and diagnosing infections caused by Legionella from water samples, lung tissue, or respiratory secretions