Medical Microbiology 8th Edition

Book Preface

Our knowledge about microbiology and immunology is constantly growing, and by building a good foundation of understanding in the beginning, it will be much easier to understand the advances of the future. Medical microbiology can be a bewildering field for the novice. We are faced with many questions when learning microbiology: How do I learn all the names? Which infectious agents cause which diseases? Why? When? Who is at risk? Is there a treatment? However, all these concerns can be reduced to one essential question: What information do I need to know that will help me understand how to diagnose and treat an infected patient? Certainly, there are a number of theories about what a student needs to know and how to teach it, which supposedly validates the plethora of microbiology textbooks that have flooded the bookstores in recent years. Although we do not claim to have the one right approach to teaching medical microbiology (there is truly no one perfect approach to medical education), we have founded the revisions of this textbook on our experience gained through years of teaching medical students, residents, and infectious disease fellows, as well as on the work devoted to the seven previous editions. We have tried to present the basic concepts of medical microbiology clearly and succinctly in a manner that addresses different types of learners. The text is written in a straightforward manner with, it is hoped, uncomplicated explanations of difficult concepts. In this edition, we challenged ourselves to improve the learning experience even more. We are using the new technology on StudentConsult. com (e-version) to enhance access to the material. New to this edition, chapter summaries and learning aids are placed at the beginning of each of the microbe chapters, and on the e-version these are keyed to the appropriate sections in the chapter. In addition, many of the figures are enhanced to assist learning. Details are summarized in tabular format rather than in lengthy text, and there are colorful illustrations for the visual learner. Clinical Cases provide the relevance that puts reality into the basic science. Important points are emphasized in boxes to aid students, especially in their review, and the study questions, including Clinical Cases, address relevant aspects of each chapter. Each section (bacteria, viruses, fungi, parasites) begins with a chapter that summarizes microbial diseases, and this also provides review material.

Our understanding of microbiology and immunology is rapidly expanding, with new and exciting discoveries in all areas. We used our experience as authors and teachers to choose the most important information and explanations for inclusion in this textbook. Each chapter has been carefully updated and expanded to include new, medically relevant discoveries. In each of these chapters, we have attempted to present the material that we believe will help the student gain an interest in as well as a clear understanding of the significance of the individual microbes and their diseases. With each edition of Medical Microbiology we refine and update our presentation. There are many changes to the eighth edition, both in the print and e-versions of the book. The book starts with a general introduction to microbiology and new chapters on the human microbiome and epidemiology of infectious diseases. The human microbiome (that is, the normal population of organisms that populate our bodies) can now be considered as another organ system with 10 times as many cells as human cells. This microbiota educates the immune response, helps digest our food, and protects us against more harmful microbes. Additional chapters in the introductory section introduce the techniques used by microbiologists and immunologists and are followed by chapters on the functional immune system. The immune cells and tissues are introduced, followed by an enhanced chapter on innate immunity and updated chapters on antigen-specific immunity, antimicrobial immunity, and vaccines. The sections on bacteria, viruses, fungi, and parasites have also been reorganized. Each section is introduced by the relevant basic science chapters and then the specific microbial disease summary chapter before proceeding into descriptions of the individual microbes, “the bug parade.” Each chapter on the specific microbes begins with a summary (including trigger words), which is keyed to the appropriate part of the chapter in the e-version. As in previous editions, there are many summary boxes, tables, clinical photographs, and original clinical cases. Clinical Cases are included because we believe students will find them particularly interesting and instructive, and they are a very efficient way to present this complex subject. Each chapter in the “bug parade” is introduced by relevant questions to excite students and orient them as they explore the chapter. Finally, students are provided with access to the new Student Consult website, which provides links to additional reference materials, clinical photographs, animations (including new animations), and answers to the introductory and summary questions of each chapter. Many of the figures are presented in step-bystep manner to facilitate learning. A very important feature on the website is access to more than 200 practice exam questions that will help students assess their mastery of the subject matter and prepare for their course and licensure exams. In essence, this edition provides an understandable text, details, questions, examples, and a review book all in one.

• To Our Future Colleagues: The Students On first impression, success in medical microbiology would appear to depend on memorization. Microbiology may seem to consist of only innumerable facts, but there is also a logic to microbiology and immunology. Like a medical detective, the first step is to know your villain. Microbes establish a niche in our bodies; some are beneficial and help us to digest our food and educate our immune system, while others may cause disease. Their ability to cause disease, and the disease that may result, depend on how the microbe interacts with the host and the innate and immune protective responses that ensue. There are many ways to approach learning microbiology and immunology, but ultimately the more you interact with the material using multiple senses, the better you will build memory and learn. A fun and effective approach to learning is to think like a physician and treat each microbe and its diseases as if it were an infection in your patient. Create a patient for each microbial infection, and compare and contrast the different patients. Perform role-playing and ask the seven basic questions as you approach this material: Who? Where? When? Why? Which? What? and How? For example: Who is at risk for disease? Where does this organism cause infections (both body site and geographic area)? When is isolation of this organism important? Why is this organism able to cause disease? Which species and genera are medically important? What diagnostic tests should be performed? How is this infection managed? Each organism that is encountered can be systematically examined. Use the following acronym to create a clinical case and learn the essential information for each microbe: DIVIRDEPT. How does the microbial disease present in the patient and the differential diagnosis? How would you confirm the diagnosis and identify the microbial cause of disease? What are the virulence properties of the organism that cause the disease? What are the helpful and harmful aspects of the innate and
immune response to the infection? What are the specific conditions or mechanisms for replicating the microbe? What are all the disease characteristics and consequences? What is the epidemiology of infection? How can you prevent its disease? What is its treatment? Answering the DIVIRDEPT questions will require that you jump around in the chapter to find the information, but this will help you learn the material. For each of the microbes, learn three to five words or phrases that are associated with the microbe—words that will stimulate your memory (trigger words, provided in the new chapter summary) and organize the diverse facts into a logical picture. Develop alternative associations. For example, this textbook presents organisms in the systematic taxonomic structure (frequently called a “bug parade,” but which the authors think is the easiest way to introduce the organisms). Take a given virulence property (e.g., toxin production) or type of disease (e.g., meningitis) and list the organisms that share this property. Pretend that an imaginary patient is infected with a specific agent and create the case history. Explain the diagnosis to your imaginary patient and also to your future professional colleagues. In other words, do not simply attempt to memorize page after page of facts; rather, use techniques that stimulate your mind and challenge your understanding of the facts presented throughout the text and it will be more fun. Use the summary chapter at the beginning of each organism section to review and help refine your “differential diagnosis” and classify organisms into logical “boxes.” Get familiar with the textbook and its bonus materials and you will not only learn the material but also have a review book to work from in the future. No textbook of this magnitude would be successful without the contributions of numerous individuals. We are grateful for the valuable professional help and support provided by the staff at Elsevier, particularly Jim Merritt, Katie DeFrancesco, and Rhoda Howell. We also want to thank the many students and professional colleagues who have offered their advice and constructive criticism throughout the development of this eighth edition of Medical Microbiology. Patrick R. Murray, PhD; Ken S. Rosenthal, PhD;
and Michael A. Pfaller, MD