Mechanisms of disease

Abstract This chapter reviews key microbiological concepts and the mechanisms by which pathogens cause disease. It begins by defining colonization, infection, and the categories of pathogens. It then describes how microorganisms attach, invade, and persist in the host. The chapter goes on to explain viral and bacterial adhesion mechanisms, as well as survival strategies and the role of toxins in disease. Clinically relevant examples, such as HIV, influenza, cholera toxin, and tetanus toxin, are used to illustrate these processes. All of the chapter’s information maps to the RCEM Basic Sciences syllabus, making it relevant to Emergency Medicine practice and the examination.