The most dynamic, comprehensive, and student-friendly text on the nature of microorganisms and the fascinating processes they employ in producing infectious disease For more than a quarter-of-a-century this engaging text has been unmatched in its ability to help students understand the nature of microorganisms and their role in the maintenance of health or causation of disease. Through a vibrant, accessible approach, Ryan & Sherris Medical Microbiology delves into the significance of etiological agents, the pathogenic processes, epidemiology, and the basis of therapy for infectious diseases. This ninth edition reflects the latest developments in the field and includes a host of learning aids including clinical cases, USMLE®-type questions, marginal notes, full-color art, and more.