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Patho - Exam 4 > Infectious Diseases > Flashcards

Infectious Diseases Flashcards

Lecture 32 - Exam 4

1
Q

List the different classes of pathogens

A

Viruses, bacteria, fungi, parasites

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2
Q

List the characteristics of a virus

A
  • Obligate intracellular pathogen
    cannot reproduce outside of cells
  • Parts include: capsid & genome
  • Some are enclosed w/in an envelope derived from the cytoplasmic membrane of the host cells
  • Cause lysis & death of the host cell during replication
  • Can remain in a latent, nonreplicating state for long periods w/o causing disease
  • Some cause cancer
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3
Q

List example(s) of a virus

A

varicella zoster virus (chicken pox first -> shingles later)
HPV -> cervical cancer

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4
Q

List the characteristics of bacteria

A
  • Prokaryotic
  • Microscopic shapes
    (cocci, bacilli, spirilla)
  • common on high-touch surfaces
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5
Q

List some example(s) of bacteria

A

Spirochete, Mycoplasmas, Rickettsiaceae, Chlamydiaceae

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6
Q

List characteristics of Spirochete

A

Anaerobic bacteria

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7
Q

List example(s) of spirochete

A

Bacteria:
Borrelia burgdorferi - Lyme Disease
Treponema pallidum - Syphilis

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8
Q

List characteristics of Mycoplasmas

A

Much smaller than other bacteria
No cell wall - resistant to cell-wall inhibiting antibiotics like penicillins

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9
Q

List example(s) of mycoplasmas

A

Mycoplasma pneumoniae - Pneumonia

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10
Q

List characteristics of Rickettsiaceae

A
  • Bacteria
  • Obligate intracellular pathogens
  • Transmitted via arthropods vectors (mites, flea, ticks, lice)
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11
Q

List example(s) of Rickettsiaceae

A

Rickettsia rickettsii - Rocky Mountain spotted fever

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12
Q

List characteristics of Chlamydiaceae

A
  • Bacteria
  • Obligate intracellular pathogens
  • Transmitted via person-to-person contact
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13
Q

List example(s) of Chlamydiaceae

A

Chlamydia trachomatis
- sexually transmitted
- causes conjunctivitis in newborns

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14
Q

How do fungi become pathogens?

A
  • Intact immune mechanism and competition for nutrients provided by the bacterial flora normally keep colonizing fungi in check
  • A disease or an antibiotic therapy can upset the balance, permitting opportunistic infections
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15
Q

List characteristics of fungi

A
  • not all fungi are pathogens
  • microscopic
  • can be unicellular (yeasts) or multicellular (molds)
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16
Q

List examples of fungi

A

Superficial mycoses
Systemic mycoses

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17
Q

List characteristics of superficial mycoses

A
  • Fungi
  • Dermatophytosis - grow on the surface
  • Caused by dermatophytes whose infection is limited to the cooler cutaneous surfaces
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18
Q

List example(s) of superficial mycoses

A
  • Ringworm
  • Athletes foot (tinea pedis)
  • Jock itch (tinea cruris)
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19
Q

List characteristics of systemic mycoses

A

Serious fungal infections of the deep tissue - rare
“Fungus that can grow inside our body”

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20
Q

List example(s) of systemic mycoses

A

Candidiasis (yeast infection)
- Opportunistic infection of candida albican, which is commensal flora in skin, mucous membranes & GI tract
Aspergillosis
- A lethal form of pneumonia caused by Aspergillus, a common mold in people with lung diseases or immunocompromised patients

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21
Q

List examples of parasites

A

Protozoa
Helminths
Parasitic arthropods

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22
Q

List characteristics of Protozoa

A
  • Parasites
  • Unicellular animals
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23
Q

List example(s) of Protozoa

A
  • Plasmodium (malaria)
    vector borne via mosquitos
  • Entamoeba histolytica (amebic dysentery, or amoebiasis)
    via contaminated water/food
  • Giardia duodenalis (giardiasis)
    via contaminated water/food
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24
Q

List characteristics of Helminths

A
  • Wormlike parasites
  • Transmission primarily through the ingestion of fertilized eggs (ova) or the penetration of infectious larval stages through the skin
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25
Q

List example(s) of Helminths

A

Roundworms
Tapeworms
Flukes

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26
Q

List characteristics of parasitic arthopods

A
  • Ectoparasites
  • May serve as vectors of other infection diseases, such as the bubonic plague
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27
Q

List example(s) of parasitic arthropods

A

mites (scabies)
chiggers
lice (head, body, pubic)
fleas

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28
Q

List the different modes of transmission of pathogens

A

penetration, direct contact, ingestion, inhalation

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29
Q

List the different sources of pathogens

A

endogenous
exogenous
person
fomites
animal
vector
place

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30
Q

Describe penetration as a mode of transmission of pathogens

A

Any disruption may allow the invasion of pathogens, which normally cannot penetrate intact skin or mucous membranes

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31
Q

List examples of penetration as a mode of transmission of pathogens

A

abrasions, burns, needles, insect & animal bites

32
Q

Describe direct contact as a mode of transmission of pathogens

A

STIs - transmitted by the exposure of the intact skin or membrane to pathogens

Congenital infection - infection of a child during gestation or birth from mother (vertical transmission)

33
Q

List examples of congenital infections

A

“TORCH”
- Toxoplasmosis
- Others
(syphilis, varicella zoster, parvovirus B19)
- Rubella
- Cytomegalovirus infection
- Herpes simplex virus

Also HIV

34
Q

Define Congenital infection

A

Infection of a child during gestation or birth from mother (vertical transmission)

35
Q

Describe ingestion as a mode of transmission of pathogens

A

typically ingesting contaminated food or water
- The low pH of the gastric acid acts as a barrier for many pathogens, but some are resistant to the low pH
- the normal bacterial flora of the bowel typically also compete with pathogens

36
Q

What is “infectious dose”?

A

the minimum amount of pathogen you need to be exposed to to be infected

37
Q

When a pathogen is resistant to stomach pH, how is the infectious dose affected?

A

When pathogens are resistant to the stomach barrier, the minimum infectious dose is much lower

38
Q

List examples of pathogens that are resistant to the stomach’s low pH

A

shigella (bacteria)
giardia (protozoa)

39
Q

List examples of ingestion as a mode of transmission of pathogens

A

cholera
typhoid fever
amoebic dysentery
food poisoning

40
Q

Describe inhalation as a mode of transmission of pathogens

A
  • Airborne pathogens
  • The respiratory tract is typically equipped with multiple-tiered defense system
    Mucous membrane, coughing, antibodies & enzymes, phagocytosis, etc
  • Smoking & diseases such as cystic fibrosis impair the defense system
41
Q

List examples of inhalation as a mode of transmission of pathogens

A
  • Bacterial pneumonia, meningitis, tuberculosis
  • Viral infections:
    Measles, mumps, chickenpox, influenza, common cold, COVID
42
Q

Define endogenous source of pathogens

A

Opportunistic infection acquired from the host’s own microbial flora

43
Q

Define exogenous source of pathogens

A

acquired from the environment (water, food, soil, air)

44
Q

Define “person” as a source of pathogens

A

direct contact with other people

45
Q

Define “fomites” as a source of pathogens

A

inanimate objects contaminated with infected body fluids

46
Q

Define animal as a source of pathogens

A

zoonoses - infectious diseases passed from other animal species to humans

47
Q

Define zoonoses

A

infectious diseases passed from other animal species to humans

48
Q

List examples of zoonoses

A

Rabies, HIV, plague, influenza, SARS, MERS

49
Q

Define vector as a source of pathogens

A

biting arthropod

50
Q

List example(s) of pathogens spread by vectors

A

Lyme disease - deer ticks
West Nile virus - mosquitos

51
Q

Define place as a source of pathogens

A

Nosocomial infection - healthcare associated infections
Community acquired infection - non-healthcare associated infections

52
Q

Define nosocomial infection

A

Healthcare associated infection

53
Q

Define commensalism

A

The colonizing bacteria acquire nutrition, and the host gets neither benefit nor harm.

(commensal bacteria in a human body (normal flora) are 10x more than human cells)

54
Q

Define mutualism

A

Both the microorganism & the host derive benefits from the interaction

55
Q

Define incidence

A

the number of new cases of an infectious disease that occur within a defined population (e.g., per 100,000 people) over an established period of time (e.g., monthly, quarterly, yearly)

56
Q

Define disease prevalence

A

The number of active cases at any given time in a population

57
Q

Define endemic

A

relatively stable incidence & prevalence in a particular geographic region
(ex. common cold is endemic)

58
Q

Define epidemic

A

an abrupt and unexpected increase in the incidence of disease over endemic rates
(obesity is sometimes described as an epidemic in the US)

59
Q

Define pandemic

A

Refers to the spread of disease beyond continental boundaries
(COVID was a pandemic)

60
Q

List examples of pathogens spread via fomites

A

Rhinovirus through shared toys
HIV & HepB via shared syringes

61
Q

Name the characteristics of the stages of the disease course

A

Incubation period
Prodromal stage
Acute stage
Convalescent stage
Resolution stage

62
Q

Describe the incubation period as a characteristic of the stages of the disease course

A

Active replication of a pathogen without recognizable symptoms

63
Q

Describe the prodromal stage as a characteristic of the stages of the disease course

A
  • Initial appearance of symptoms
  • Mild fever, myalgia, headache & fatigue
    Somewhat nonspecific
64
Q

Describe the acute stage as a characteristic of the stages of the disease course

A
  • Max impact of the infectious process
  • Inflammation & tissue damage
    More specific
65
Q

Describe the convalescent stage as a characteristic of the stages of the disease course

A

Progressive elimination of the pathogen

66
Q

Describe the resolution stage as a characteristic of the stages of the disease course

A

Total elimination of a pathogen

67
Q

List the classes of virulence factors

A

exotoxins, endotoxins, adhesion factors, evasive factors, invasive factors

68
Q

Define virulence factor

A

Substances or products generated by infectious agents that enhance their ability to cause disease

69
Q

Describe the pathological functions of exotoxins

A
  • Inactivate key cellular components of host cells
    Ex. diphtheria toxin inhibits protein synthesis
  • Superantigens
    Induce excessive & nonspecific inflammatory responses
70
Q

Describe the pathological functions of endotoxins

A

Can induce clotting, bleeding, inflammation, hypotension & fever
(Endotoxic shock)

71
Q

Describe the pathological functions of adhesion factors (adhesins)

A
  • Bind to macromolecules on the surface of host cells
  • Adhesion is critical for the colonization of the pathogens
  • Some pathogens form a mucous layer (slime)
72
Q

Describe the pathological functions of evasive factors

A
  • Inactivate host’s immune system.
    Ex. leukocidins form pores in the cell membrane of neutrophils and macrophages.
  • Some pathogens survive and reproduce within phagocytes after phagocytosis by neutralizing lysosomal contents with evasive factors
73
Q

Describe the pathological functions of invasive factors

A
  • Facilitate the penetration of anatomic barriers.
    Ex. Pseudomonas aeruginosa collagenase breaks skin
74
Q

Define exotoxin

A
  • Proteins released by pathogenic bacteria
  • Inactivate key cellular components
    ex. diphtheria toxin inhibits protein synthesis
  • Many are superantigens inducing excessive & nonspecific inflammatory response
75
Q

Define endotoxin

A
  • Lipids & polysaccharides, not released
    Ex. lipopolysaccharides
  • Can induce clotting, bleeding, inflammation, hypotension, and fever (endotoxic shock)
76
Q

Describe the actions of a superantigen

A
  • Bind to the MHC of antigen-presenting cells and T-cell receptors
  • T cells are activated regardless of the antigen presented on MHC
    -> Induces excessive & nonspecific inflammatory response

Patho - Exam 4 (6 decks)

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