Dr John Atack is an expert on host-adapted bacterial pathogens, with a specific focus on understanding how bacterial pathogens randomly and reversibly switch gene expression, a process known as phase-variation. John and his group have a particular focus on several human and animal adapted bacterial pathogens, such as the Streptococci and non-typeable Haemophilus influenzae (NTHi), that cause a range of diseases such as middle ear infections in children, chronic lung disease in adults, and zoonotic meningitis. They seek to understand how random gene expression (phase-variable genes and phasevarions) influences the pathobiology of these organisms using a variety of biochemical and molecular biology techniques.