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2015-05-01 12:56:12

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  1. Symbiosis = Life Together
    Category of symbiosis

    • 1. Commensalism +   0
    • 2. Mutualism        +   +
    • 3. Parasitism        +   -
  2. Normal Flora / Normal Microbiota
    Microorganisms that colonize but do not produce disease under normal conditions
  3. Normal Flora
    Provides protection by:

    –Microbial antagonism

    –Competitive exclusion
  4. Microbial antagonism
    the method of using established cultures of microorganisms to prevent the intrusion of foreign strains
  5. Competitive exclusion
    two species cannot coexist in the same ecological niche for very long without one becoming extinct or being driven out because of competition for limited resources
  6. Microbial antagonism Competitive exclusion examples
    • taking up space
    • taking up nutrients
    • producing waste products
    • Making itndifficult for a pathogen to come in and take over
  7. Pathology
    scientific study of disease
  8. Etiology
    cause of disease
  9. Pathogenesis
    origin & development of disease
  10. Virulence
    degree of pathogenicity
  11. Virulence factors
    molecules produced by the pathogen that allows it to thrive
  12. Etiology of Infectious Disease
    Determined by  Koch’s Postulates

    Difficulties? Some organisms are difficult to culture. Ex: Mycobacterium tuberculosis is difficult to culture because it is a fastidious bacteria
  13. Colonization
    the presence and growth of organism without observable clinical symptoms

    ex: MRSA - colonize in employees noses
  14. Infection
    invasion of bacteria in tissue resulting in illness 

    characterized by clinical signs and symptoms such as fever
  15. Disease signs
    discovered by phsysician
  16. disease symptoms
    symptoms reported by patient
  17. disease syndrome
    association of the signs and symptoms
  18. Primary infection
    an acute infection that causes the initial illness

    a disease that a person gets before getting another disease

    ex: you go into the hospital with an illness but come out with another illness
  19. secondary infection
    occurs when a person is infected with a disease that makes them more susceptible to additional infections

    ex: UTI
  20. Primary pathogen
    causes disease just because of its presence in a host
  21. Opportunistic pathogens
    causes disease in immuno-compromised patients
  22. Immunocompromised hosts
    hosts with depressed resistance
  23. Incidence
    the number of people in a population who develop the disease during a particular time

    new cases
  24. Prevalence
    the number of people in a population who develop a disease at a specific time regardless of when it first appeared 

    accounts for new and old cases
  25. Sporadic disease
    occurs occasionally
  26. Endemic
    Dz constantly present in population
  27. Epidemic
    Many in given area acquire certain dz in short period
  28. Pandemic disease
    An epidemic dz that occurs worldwide
  29. Acute
    •Develops rapidly but lasts short time
  30. Chronic
    •Disease develops more slowly, reaction less severe but last long time
  31. Latent
    •Causative agent remains inactive for a while, then activates (shingles)
  32. Disease carriers / subclinical infection
    •No noticeable illness (polio virus & hepatitis A)
  33. Local
    limited to a particular area
  34. Systemic
    spreads throughout your body
  35. Sepsis
    •blood poisoning
  36. In blood - suffix “-emia”
    –Bacteremia - 



  37. Disease Reservoirs
    Source which harbor disease causing organism. Serves as potential source for disease outbreak
  38. Disease Reservoirs 2
    Human - Our most common source

    • Symptomatic reservoirs –active
    • infection – is ill
  39. Disease Reservoirs 3

    –Animal reservoirs – Zoonoses

    –Environmental reservoirs - Soil and Water
  40. –Asymptomatic reservoirs
    showing no evidence of having a disease
  41. Communicable disease
    infectious disease coming from another infected host; directly and indirectly

    Contagious – easily transferable communicable disease
  42. Noncommunicable disease
    • not spread from one host to another
    • ex: tooth decay, cancer, acne
  43. Contact Transmission
    •Direct contact – touching, kissing

    •Indirect contact – inanimate surface

    •Droplet transmission – sneezing, coughing
  44. Vehicle Transmission



    –via droplet nuclei

    –Aerosolized pathogen
  45. Mechanical Vector
    •Microbe carried on the surface of the vector
  46. Biological Vector
    •Microbe replicates within vector
  47. Nosocomial Infection
    Hospital-Acquired Infection

    •Affects 5-15% of hospital patients, ~ 2 million/yr.

    •Results in ~ 20,000 deaths per year
  48. Nosocomial Infection 2
    •8th leading cause of death

    •Adds $4.5 billion to the cost of health care

    •#1 method of control: HANDWASHING!
  49. source of Nosocomial infection
    •Patient’s own flora; misplaced microbe!

    •Other patients

    •Hospital environment

    •Health care workers
  50. Nosocomial infection Method of Transmission
    •Medical devices

    •Health care personnel

  51. Nosocomial Infection 3
    UTI - most common, usually accounts for about 40% of all nosocomial infections. Typically related to urinary catheterization
  52. Prior to 1980’s
    • General belief that infectious diseases
    • had been conquered via antibiotics, vaccines, and improved standards of living
  53. Emerging Infectious Diseases (EIDs) history
    AIDS - early 1980’s

    Increased antibiotic resistance in Staphylococcus and Mycobacterium

    • Multi-state outbreaks of food-borne
    • illness due to various bacteria and viruses
  54. EID
    Emerging Infectious Diseases 

    infectious disease whose incidence has increased in the past 20 years and threatens to increase in the future – SARS, TB
  55. EID - Natural evolution of organisms
    –Vibrio cholerae 0139 – forms capsule

    –Avian influenza (H5N1)

    Environmental factors

         –Climate fluctuations & changes

         –Ex. Hantavirus in SW US – after El Nino (rain increases rodent #’s)
  56. Human contributions to EID
    Human contributions

    •Complacency and breakdown in public health care system

    •Changes in human behavior
  57. Human contributions to EID 2
    •Population expansion and development

    •Mass distribution and food importation

    •Wars and civil unrest
  58. Factors Contributing to EID’s -
    Natural evolution of organisms

    Environmental factors

    Human contributions

    Excessive and Inappropriate Use of Antibiotics

    Increasing population of immunosuppressed patients

    Global Travel!
  59. EID - Excessive and Inappropriate Use of Antibiotics
    –Antibiotics prescribed for viral infections

    –Antibiotics added to animal feed

    –Availability of antibiotics without prescriptions
  60. EID - Increasing population of immunosuppressed patients
    –Due to disease agents (HIV)

    • –Disease treatments - cancer chemo- and radiation therapies and transplant
    • anti-rejection drugs
  61. Epidemiology
    •Science of disease transmission

    •Includes microbiology, ecology, statistics, sociology, psychology
  62. Epidemiologists
    •our “health detectives”
  63. Father of epidemiology
    John Snow

    Investigated London Cholera Epidemic

    Mapped out all the people that died and found that they all lived by a waterpump
  64. Ignaz Semmelweis

    –puerperal sepsis (childbirth fever)

    –Promoted handwashing
  65. Florence Nightingale

    –Documented Typhus epidemic

    –Compiled statistics demonstrating that disease, poor food, and unsanitary conditions were killing soldiers

    –Pioneered nursing and patient care
  66. Epidemiological Studies - Types of studies



    4.Case Reporting