Transcript Chapter 26
Chapter 26 Infectious Diseases a LANGE medical book Pathophysiology of Disease An Introduction to Clinical Medicine Seventh Edition CHAPTER 4 Infectious Diseases Infection and the Body’s Defense Mechanisms • There are several microorganisms that live on and in the human body that do not produce signs of illness • Referred to as indigenous flora, these bacteria can also be helpful • Pathogens are microorganisms that produce signs of illness Infection and the Body’s Defense Mechanisms • The innate immune system – Structural barriers • Skin and mucous membranes – Inflammatory response • The acquired immune system – Humoral system – Cellular immune system – Immunization Most Frequent and Serious Problems • Bacterial Infections – Secondary infections, sexually transmitted infections • Viral Infections – Upper respiratory illnesses – Gastroenteritis – Cold sores – HIV Most Frequent and Serious Problems • Rickettsial Infections – Rocky Mountain Spotted Fever • Fungal Infections – Candida Most Frequent and Serious Problems • Protozoal Infections – Malaria • Helminth Infections – Roundworms Symptoms, Signs, and Tests • Rapid onset of muscle aches, fatigue, fever, malaise • Physical exam – Many lesions are characteristic enough to be diagnostic Symptoms, Signs, and Tests • Laboratory testing – Culture: most commonly used for bacteria • Once the bacteria is identified, it is tested for susceptibility to various antibiotics – Gram stains • Allow for an “educated guess” about antibiotic coverage while waiting for the organism to be identified Specific Diseases • Staphylococcal Infections – S. aureus can develop into Methicillin Resistant S. aureus and cause serious illness in some patients Specific Diseases • Group A Streptococcal Infections – Strep A is the most virulent, and common in upper respiratory infections – Scarlet fever – Necrotizing fascitis Specific Diseases • Streptococcus pneumoniae – Common cause of pneumonia • Neisseria meningitidis – Meningococcal Menigitis Specific Diseases • Haemophilus influenzae – Common cause of ear infections and sinusitis – Other serious illnesses caused by this bacteria have been eliminated through immunization Specific Diseases • Legionellosis – Gram negative bacteria that thrives in water reservoirs and cooling towers – A common cause of community acquired pneumonia Specific Diseases • Nonfastidious Gram-Negative Rods – Enteric bacteria – When these bacteria cause sepsis, they often lead to septic shock with a mortality rate of up to 50% Specific Diseases • Anaerobic Bacteria – Bacteria that grow with little oxygen • Sexually Transmitted Infections Specific Diseases • Anaerobic Bacteria – Bacteria that grow with little oxygen • Sexually Transmitted Infections Specific Diseases • Bacterial Infections Mediated by Exotoxins – Clostridium Family • Tetani (tetanus) • Botulinum (botulism) • Difficile (entercolitis, not exotoxin mediated) • Perfringens (gas gangrene) – Diptheria Specific Diseases • Bordetella pertussis (whooping cough) – Not as prevalent in young children due to immunization, though resurgence in older children and adults suggests the vaccine needs to be re-administered Specific Diseases • Mycoplasma Disease – Common cause of atypical pneumonia • Lyme Disease – Tick borne disease Specific Diseases • Plague • Tularemia • Brucellosis • Leprosy Specific Diseases • Viral Infections – Do not respond to antibiotic therapy and are best treated with supportive mechanisms – Few anti-viral medications are available to decrease the duration of illness – Immunization has decreased the number of viral infections Specific Diseases • Measles, Mumps, Rubella, and Varicella – Young children are immunized against these with one vaccine (MMRV) • Smallpox – No longer found in the U.S. due to successful vaccination Specific Diseases • Influenza A – Causes wide-spread respiratory disease yearly • Mononucleosis – Epstein-Barr Virus Specific Diseases • Herpes Simplex – Type I—mostly oral lesions “cold sores” – Type II—genital lesions • Human Papillomavirus – Some strains associated with the development of cervical cancer Specific Diseases • Cytomegalovirus • Human Immunodeficiency Virus – Causes AIDS • Rickettsial Infections Specific Diseases • Protozoal Disease – Malaria – Toxoplasmosis – Cryptosporidiosis • Helminthic Infections – Various “worms” – Trichinosis