Microbiology Chapter 19.txt

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Microbiology Chapter 19.txt
2010-07-21 16:46:22
Microbiology Infection Disease

Microbiology Chapter 19
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  1. Infection
    Invasion of a host by a parasite
  2. Disease
    Any change from good health
  3. Infection refers to:
    • the relationship between the host and microbe
    • the competition for supremacy between them
    • If the host loses the competition, disease occurs
  4. Normal flora occurs where
    Intestines, mouth, skin, vagina
  5. Methods of aquiring normal flora
    • During passage thru birth canal
    • Contact with feeding materials
    • Contact with medical instruments
    • Contact with other people
    • During nursing
  6. Microbiota
    Microbes that reside in the body without causing disease (in symbiosis)
  7. E. coli produces
    • Micronutrients
    • Vitamin K
  8. Mutualism
  9. Mutualism
    Both host and microbe benefit
  10. Commensalism
    • The microbe benefits and the host is unaffected.
    • This is not very common
  11. Pathogenicity
    Ability to invade the body and cause disease
  12. In parasitism, pathogens cause
    Damage and disease in the host
  13. Virulence
    • The degree of pathogenicity
    • Severity of disease
  14. An exogenous infection occurs if
    A pathogen breaches the host�s external defense and enters sterile tissue
  15. An endogenous infection occurs if
    normal microbiota enter sterile tissue
  16. Opportunistic infections occur when
    Commensals take advantage of a change in the body�s environment that favors the microbe
  17. Commensals
    A parasite that causes no harm to the host.
  18. Acute diseases
    Acute diseases develop rapidly, cause severe symptoms, and fade quickly
  19. Chronic diseases
    Chronic diseases linger for long periods of time, and are slower to develop and recede
  20. Primary and secondary diseases
    Local and systemic diseases
  21. Primary infections
    Can invade and cause disease in a healthy body
  22. Secondary infections
    Infections in someone who has another disease
  23. Local disease
    Infection in a specific area, such as a boil
  24. Systemic disease
    Systemic diseases disseminate to organs and systems
  25. Periods of progress of disease
    • Incubation
    • Prodromal symptoms
    • Acme
    • Decline
    • Convalescence
  26. Period of incubation
    The time between entry and appearance of symptoms
  27. Period of incubation variation
    • Number of organisms that entered host
    • Generation time
    • Virulence
    • Host resistance
    • Location of entry
  28. Period of prodromal symptoms
    • General symptoms
    • Malaise
    • Nausea
    • Headache
  29. Period of acme
    • Pinacle
    • Peak of disease
    • Specific symptoms appear
    • Crisis period
    • If you make it thru, you live
  30. Period of decline
    Body has won the fight and is killing off stragglers
  31. Period of convalescence
    Regain strength and return to normal
  32. Clinical disease
    Symptoms are apparent
  33. Subclinical disease
    • Symptoms are minor
    • Few obvious symptoms
  34. Barriers to disease
    • Skin
    • Mucous membranes
    • Eyes � lysozymes
    • Saliva
  35. Establishment of disease: Portal of entry
    • The portal of entry is the route an exogenous pathogen uses to enter the body
    • Area where the disease enters
    • Has to be the right entry or disease is not established.
    • IE, tetanus must enter a puncture wound, not the stomach to cause disease
  36. Establishment of disease: Dose
    • The infectious dose is the number of microbes entering the body
    • You need to get the minimum required bacteria.
    • IE, cholera you need at least a million bacteria to become infected
    • If you have a high level of resistance, you need more
  37. Establishment of disease: Tissue penetration
    Many pathogens have adhesins that allow then to adhere to specific tissues
  38. Invasiveness is
    The ability of a pathogen to penetrate tissues and spread
  39. Many pathogens use phagocytosis by body cells to
    Enter cells or pass through defenses
  40. Toxigenicity is the ability of pathogens
    to produce toxins
  41. Toxemia is
    The presence of toxins in the blood
  42. Exotoxins are
    Proteins produced during bacterial metabolism
  43. Neurotoxins act on
    The nervous system
  44. Enterotoxins act on
    The gastrointestinal tract
  45. Antitoxins are
    Produced by the host body and neutralize toxins
  46. Toxoids are
    Toxins whose toxicity has been destroyed but still elicit an immune response
  47. Endotoxins are
    • Released upon disintegration of gram-negative cells
    • They cause blood coagulation and cell rupture
  48. Endotoxin symptoms
    • Increased temperature
    • Body weakness
    • Aches
    • General malaise
    • Damage to the cardiovascular system
  49. Endotoxin shock
    • Blood pressure drops due to the endotoxins causing blood vessels to dialate
    • May occur with antibiotic treatment of diseases caused by gram-negative bacilli
  50. Establishment of disease: Enzymes
    • Can increase virulence
    • Some organisms make enzymes that increase their chances of causing disease
    • Leukocidins
    • Hemolysins
    • Coagulase
    • Streptokinase
    • Hyaluronidase
  51. Hyaluronidase
    • Enhances pathogen penetration through tissues
    • Destroys hyaluronic acid, a polysaccharide that "cements" cells together in a tissue
    • Permits organisms to spread through tissues and establish themselves at sites distant from that of the intial infection
  52. Streptokinase
    Some staphylococci produce streptokinase, which dissolves fibrin clots and allows dissemination of the bacteria
  53. Leukocidins
    • Destroy white blood cells
    • Disintegrate neutrophils and macrophages
  54. Hemolysins
    Dissolve red blood cells
  55. Coagulase
    Some staphylococci produce coagulase to form a blood clot that protects them from phagocytosis
  56. Toxins
    Weaken or harm the host body
  57. Enzymes can
    • increase the virulence of a pathogen
    • Enzymes influence virulence
  58. Biofilms
    • A layer of bacteria
    • Virulence can be enhanced in biofilms because immune cells cannot reach bacterial cells
  59. Transmission of disease
    • Cough or sneeze
    • Urine
    • Blood
    • Insect bite
    • Feces
    • Lesion
  60. Direct transmission methods
    • Person to person contact
    • Coughing
    • Animal bite
  61. Indirect transmission methods
    • Fomites
    • Arthropod vectors
    • Mechanical vectors: bug lands in feces and then later in food
    • Biological vectors: Organism lives in the bug. Bug poops on you
    • Reservoirs
    • Carriers
  62. Mechanical vectors
    Bug lands in feces and then later in food
  63. Biological vectors
    Organism lives in the bug. Bug poops on you
  64. Reservoirs
    Ecological niches where microbes live and reproduce
  65. Carriers
    Have recovered from the disease but continue to shed the disease agents
  66. Communicable diseases
    • Are contagious
    • They are transmittable among hosts in a population
  67. Noncommunicable diseases are
    • Not easily transmitted to another host
    • They are acquired directly from the environment
  68. Endemic disease
    Is habitually present at a low level in a certain geographic area
  69. Epidemic disease
    Occurs in a region in excess of what is normally found in that population
  70. Outbreak
    A more contained epidemic
  71. A pandemic
    A worldwide epidemic
  72. Globalization
    Means that diseases emerging anywhere in the world can be spread globally
  73. Zoonoses
    Diseases transmitted from other vertebrate animals to humans
  74. Nosocomial Infections
    Hospital acquired
  75. Health care-associated infections (HAIs)
    Occur as a result of receiving treatment for another condition
  76. Disease emergence and reemergence are related to:
    • Changes in land use or agriculture practices
    • Changes in human demographics
    • Poor population health
    • Pathogen evolution
    • Contamination of food sources and water supplies
    • International travel
    • Failure of public health systems
    • International trade
    • Climate change