Understanding Infectious Diseases: Definitions, Phases, and Mechanisms, Slides of Microbiology

Download Understanding Infectious Diseases: Definitions, Phases, and Mechanisms and more Slides Microbiology in PDF only on Docsity! Mechanisms of Pathogenicity Define a Few Words: e Pathogen e Pathology e Pathologist e Pathogenicity e Pathogenesis docsity.com Location of Infections e Localized Infection e Infection stays in one area e Systemic Infection ¢ Infection spreads throughout body docsity.com Disease Description Acute Disease  Has a rapid onset, usually followed by relatively  rapid recovery.  Ex. influenza  Subacute Disease  Intermediate between acute and chronic diseases.  Onset more rapid than a chronic disease but less  suddenly than most acute diseases.  Chronic Disease  Slow onset and lasts a long time.  Ex. Tuberculosis, syphilis docsity.com Symptoms Versus  Signs of a Disease Symptom of a Disease  A subjective indication that a person is  experiencing a disease. Symptomatic Disease  Experience symptoms. Asymptomatic Disease  Do not experience symptoms. Signs of a Disease  An objective sign of a disease. docsity.com Steps in the Pathogenesis of Infectious Diseases e1. Entry e 2. Attachment e 3. Multiplication e 4. Invasion e 5. Evasion of Host Defenses e 6. Damage to Host Tissue docsity.com Virulence Can use this word in 2 ways:  1. Can say that a microorganism is virulent or  avirulent.  Ex. Different strains of Corynebacterium  diphtheriae (strains that produce diphtheria). Can say that one pathogen is more virulent  than another pathogen.  Ex. Different strains of Streptococcus pyogenes. docsity.com Virulence Factors e Characteristics that allow a pathogen to attach, escape destruction, and cause disease. docsity.com Obligate Intracellular Pathogens e Pathogens must live within host cells to survive and multiply. e Ex. Rickettsias infect endothelial cells and vascular smooth muscle cells. e 2 & om ED. ay, oy oe eet ae gS Sud ‘ i 4 = 7 ° . www.cals.ncsu.edu www.microbelibrary.org ® docsity.com Facultative Intracellular Pathogens e Capable of surviving in an intracellular and extracellular environment. e Mechanisms of survival e Ex. Mycobacterium tuberculosis Scanning Electron Micrograph of Mycobacterium tuberculosis www.sunysb.edu docsity.com Capsules e Encapsulated bacteria are often harder to engulf by phagocytic white blood cells because they lack surface receptors. e Phagocytes have difficulty engulfing this bacteria. www.cbc.ca docsity.com Exoenzymes e Necrotizing Enzymes e Coagulase e Kinases e Hyaluronidase e Collagenase e Hemolysin e Lecithinase docsity.com Toxins Poisonous substances that are produced by a  microorganism that often cause disease.  2 categories of toxins:  1. endotoxins  Part of cell wall of gram‐negative bacteria that  can cause problems.  2. exotoxins  Toxins produced within cells and then released  from the cells. docsity.com Endotoxins e Ex. Septicemia caused by gram-negative bacteria. e Caused by the lipid portion of its cell wall which is the endotoxin. e Causes chills, fever, extreme exhaustion, and possibly septic shock. ® docsity.com