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Infectious Disease and Medical Microbiology > Introduction and Historical Perspective of Infectious Disease > Flashcards

Introduction and Historical Perspective of Infectious Disease Flashcards

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1
Q

Early treatment options for infectious disease

A

-Isolation -Destruction of “soiled” materials -Natural remedies -Bloodletting

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2
Q

Variolation

A

Preventive measure for smallpox where dried pox crusts were inhaled or inserted into open wounds to confer protection. Inconsistent and dangerous

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3
Q

Anton van Leeuwenhoek

A

First direct observation of microbes “animalcules”

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4
Q

Edward Jenner

A

Vaccine development Previous ix with cowpox confers protection against smallpox.

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5
Q

Ignaz Semmelweiss

A

Importance of hand washing

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6
Q

John Snow

A

Disease transmission via polluted water

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7
Q

Louis Pasteur

A

-Mild heating of food delays spoilage -Development of Germ Theory -Development of attenuated vaccines (cholera) -Development of rabies vaccine

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8
Q

Joseph Lister

A

Use of aseptic surgical technique to reduce postoperative ix’s

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9
Q

Robert Koch

A

-Proof of Germ Theory -Developed Koch’s postulates - isolation of MO and re-ix

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10
Q

Alexander Fleming

A

Discovery of penicillin as chemotherapeutic agent

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11
Q

Further Development in ID

A

-VACCINES -Vaccines against viral ix’s -Vaccines against childhood disease -Eradication of smallpox

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12
Q

% Deaths caused by infectious agents worldwide

A

20

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13
Q

4 major death causing infectious agents worldwide

A

-Lower RT ix’s -Diarrheal ix’s -Tuberculosis -HIV/AIDS

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14
Q

Current state of infectious disease

A

-Still major problem worldwide, much more prevalent in developing world -New ix’s continue to emerge -Some ix’s are re-emerging

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15
Q

Examples of emerging/re-emerging infectious diseases

A

-HIV -Hantavirus -HTLV 1 2 3 4 -Herpes viruses -E coli strains -Borrelia burgdorferi

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16
Q

Aspects of modern life that encourage disease transmission

A

-Climate change -Slowed development of vaccines, antimicrobials -Altered sexual behavior -Altered patterns of trade -Altered agricultural practice -Overuse/misuse of antibiotics -Population growth -Emergence of new strains/ix’s -Bioterrorism

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17
Q

Prokaryotes

A

-No membrane bound nucleus or organelles -70S ribosome -No histones -One circular chromosome +/- plasmids -Cell wall usually present

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18
Q

Eukaryotes

A

-Membrane bound nucleus and organelles -80S ribosome -Multiple linear chromosomes -Histones present -Cell wall only in fungi

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19
Q

Bacteria

A

-Prokaryotic -Cell wall of peptidoglycan (target for abx) -Replication either IC or EC -Small (1-20 micrometers) -Variety of shapes

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20
Q

Fungi

A

-Eukaryotic -Exist in two forms: -Yeast form - unicellular, reproduce asexually -Filamentous mold form - multicellular, reproduce asexually or sexually -Thick cell wall

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21
Q

Parasites

A

-Eukaryotic -Range in size -Protozoa - small -Arthropods - insects -Helminths - worms

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22
Q

Viruses

A

-Not cellular -Nucleic acid surrounded by protein coat and sometimes enveloped -Obligate IC parasite

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23
Q

Prions

A

-Not cellular -Spongiform encephalopathies -Abnormally folded proteins that induce abnormal folding in other proteins -Resistant to disinfection -eg. Creutzfeld-Jakob

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24
Q

Medical Nomenclature

A

Genus name + species name

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25
Q

Subspecies

A

Members of same species with subtle physical, metabolic or biochemical differences -eg. E. coli strains

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26
Q

Host

A

Animal capable of supporting growth of MO

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27
Q

Pathogen

A

Agent that causes disease

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28
Q

Pathogenicity

A

Ability to cause disease

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29
Q

Virulence

A

Degree/intensity of pathogenicity

30
Q

Colonization

A

Microbial reproduction on host without disease

31
Q

Infection

A

Presence of MO on/in a host

32
Q

Infectious Disease

A

When presence of ix results in a diseased state, due to MO factors or host immune response

33
Q

Outcome of interaction between MO and host depends on (3)

A

-Site of ix -Host’s immune response -Virulence of MO

34
Q

Strict pathogens

A

Always cause disease

35
Q

Opportunistic pathogens

A

MO that does not usually cause disease but can cause disease if introduced into sterile site or in immunocompromised patients eg. S. aureus, E. coli

36
Q

Normal flora

A

-Normal microbial population found associated with healthy hosts in nose, GI tracts, urinary tract, -Mostly bacteria -10(14) cells

37
Q

Development of normal flora

A

-Fetus is sterile -Initial normal flora from mother’s genital tract, hospital setting, colonizes nasopharyngeal area, GI tract -Influenced by diet (eg. breast milk results in lactobacillus in flora) -Can have permanent and transient components

38
Q

Alterations of normal flora done by (4)

A

Physiological conditions -pH, nutrient status, oxygen concentration -antimicrobial substances (eg. lysozyme) -types of other flora present Host factors: -age, diet, health status, hygiene

39
Q

Common flora of large bowel

A

-Strep faecalis -Bacteroides -Fusobacterium -Escherichia coli

40
Q

Common flora of fecal material

A

-Bacteroides -Bifidobacterium -Eubacteria

41
Q

Beneficial effects of normal flora (4)

A

-Involved in metabolism (eg. oxalates) -Involved in nutrient production (eg. vitamin K, B) -Immune system development -Protects against infections

42
Q

Normal flora protects against other ix’s (3)

A

-Exclusion of other MO’s -Production of toxic metabolites (eg. Bifidobacterium reduces pH in gut) -Production of antibacterial factors

43
Q

Negative effects of flora (2)

A

-Source of pathogens -Metabolic activity of flora can be detrimental -eg. biotransformation into carcinogens

44
Q

Manipulating & Altering Normal Flora

A

Unintentional

  • Long term abx use (make pt susceptible to C. diff infections)
  • Hospitalization (replacement of normal flora with Gram (-) rods

Intentional

  • Bone marrow transplant pt’s (remove flora so that they can’t cause opportunistic infections
  • Probiotics - consumptions of live bacteria to alter flora (often Lactobacillus and Bifidobacterium, enteric coating used to get to GI tract)
  • Prebiotics - consumption of non-digestible foods to stimulate growth and activity in GI tract (eg. soluble fibre)
45
Q

Probiotics useful for (4)

A
  • Bloating and diarrhea due to lactose intolerance
  • Diarrhea to rotavirus enteritis in infants
  • Diarrhea due to abx use
  • Ix’s in digestive tract
46
Q

Stages of Infectious Disease

A
  • Attachment
  • Spread
  • Multiplication
  • Evasion of host defenses
  • Exit (shedding)
  • Transmission
  • Damage to host
47
Q

Entry, Exit, Transmission

A

MO must be able to attach/penetrate host defense, multiply, and exit from host to find another in order to be infective

48
Q

Modes of Transmission (6)

A
  • Ingestion
  • Inhalation
  • Trauma
  • Needlestick injuries
  • Arthropod bites
  • Sexual transmission
49
Q

Receptor molecules

A
  • Present on cells, provides specificity of ix
  • Have normal function
  • After binding, MO’s can either enter cell or replicate on surface
  • Presence/absence of receptor molecules determines whether ix will occur or not
50
Q

Intracellular Pathogens

A
  • Use cellular nutrients for own growth
  • Protected against host defenses somewhat
  • More difficult to target with therapeutics
  • Some are obligate - only replicate inside cells
51
Q

Extracellular pathogens

A
  • Take nutrients from tissue fluids or directly from cells
  • Able to grow and reproduce freely
  • Can spread throughout body
  • Size and protective coating can protect against phagocytosis
  • Vulnerable to host immune host defenses
52
Q

Exit and Transmission

A
  • To be infective, MO must exit host and spread to new host
  • If unable to spread host to host, not going to affect population as a whole
53
Q

Factors Affecting Transmission (3)

A
  • Number of MO’s shed (not all shed are infective, MO’s that induce large shedding most likely to be more infective
  • Number of MO’s required to infect (ID) - varies greatly
  • Stability in environment (resistant to drying, thermal inactivation or able to sporulate makes MO more infective)
54
Q

Other Factors Affecting Transmission

A
  • Microbial genetic factors (Different strains have different transmission rates)
  • Activity of host (eg. coughing, sneezing, diarrhea makes transmission easier)
  • Coughing, sneezing, diarrhea benefits host by clearing MO’s and benefits MO’s by making transmission easier
55
Q

Three Types of Transmission

A
  1. Human to human (respiratory, fecal oral, sexually transmitted)
  2. Verterbrate to human (through animal consumption or pets) (called zoonoses)
  3. Biting arthropod (eg. malaria through mosquitos)
56
Q

Two Types of Human to Human Transmission

A
  1. Vertical transmission (from parent to child through sperm, ova, blood, breast milk)
  2. Horizontal transmission (transmisison to both related and unrelated individuals)
    - Respiratory, fecal-oral, sexually transmitted
57
Q

Types of Biting Arthropod Transmission (3)

A
  1. Passive transmission (uncommon)
    - insect carries MO on body, in intestine, transmits from human to human, eg. C. trachomatis to eyes
  2. Biologic transmission (more common)
    - arthropod is essential step in MO’s life cycle, can’t be transmitted to new human without going through arthropod first
    - either through direct injection or contamination of blood at time of feeding
    - eg. malaria, typhoid, plague
  3. Passive transmission via invertebrates used for food
    - invertebrate accumulates MO in body, humans consume invertebrate and become infected
    - eg. V. cholerae in shellfish
58
Q

Zoonoses

A
  • Animal diseases that are transmitted to humans via animal vectors
  • Transmisison by inhalation, scratches, ingestion of animal, contact, bites, contamination of food and water
59
Q

Epidemiology of zoonoses depends on (3)

A
  • Geography (local food preferences, habitat overlap)
  • Occupation (eg. butchers, farm workers)
  • Contact with domestic animals (eg. pets)
60
Q

Reservoir

A

Site or location in environment where MO is found living and can be transmitted to humans

61
Q

Carrier

A

Infected individual who is potential source of infection

62
Q

Acute Carrier

A

Carrier who is in acute phase of disease

63
Q

Convalescent Carrier

A

Carrier who has recovered from disease but is still harboring MO and can infect others

64
Q

Healthy Carrier

A

Harbors pathogen but is not showing symptoms

65
Q

Incubatory Carri

A

Carries pathogen but is not yet ill

66
Q

Fomites

A

Inanimate objects that can carry pathogenic organisms (eg. bedding, utensils)

67
Q

Vectors

A

Organisms that can transmit pathogen (eg. arthropods, animals)

68
Q

Sporadic Disease

A

Occuring occasionally at irregular intervals (eg. typhoid)

69
Q

Endemic Disease

A

Low level frequency at somewhat regular intervals (eg. common cold)

70
Q

Hyperendemic Disease

A

Increase in frequency above endemic rates but not yet epidemic rates

eg. common cold in winter months

71
Q

Epidemic Disease

A

Sudden increase beyond expected levels (eg. influenza in some years)

72
Q

Pandemic Disease

A

Increase in frequency in large population over wide ranges of area

(eg. influenza in 1960’s, AIDS)

Infectious Disease and Medical Microbiology (11 decks)

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