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Microbiology > Lecture 11: Pathogenicity & Epidemiology > Flashcards

Lecture 11: Pathogenicity & Epidemiology Flashcards

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1
Q

What is the ability to cause disease?

A

Pathogenicity

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2
Q

What is the extent of pathogenicity?

A

Virulence

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3
Q

What are virulence factors?

A

Adhesion factors
Extracellular enzymes
Toxins
Antiphagocytic factors

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4
Q

What are the the adhesion factors on microbes?

A

Surface lipoproteins or glycoproteins called ligands bind to receptors on host cells

Ability to change of block the ligand or its receptor can prevent infection

Inability to make attachment proteins or adhesions renders the microorganisms arvirulent

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5
Q

Which enzyme coagulate blood?

A

Coagulase

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6
Q

Which enzyme digest fibrin clots?

A

Kinases

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7
Q

Which enzyme hydrolyses hyaluronic acid?

A

Hylaluronidase

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8
Q

Which enzyme hydrolyzes collagen?

A

Collagenase

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9
Q

Which enzyme destroy IgA antibodies?

A

IgA proteases

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10
Q

Which enzyme take iron from host iron-binding proteins?

A

Siderophores

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11
Q

Which enzyme alter surface proteins?

A

Antigenic variation

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12
Q

What are substances that contribute to pathogenicity?

A

Toxin

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13
Q

What is the ability to produce a toxin?

A

Toxigenicity

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14
Q

What is the presence of toxin the host’s blood?

A

Toxemia

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15
Q

What is the inactivated toxin used in vaccine?

A

Toxoid

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16
Q

What are antibodies against a specific toxin?

A

Antitoixin

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17
Q

Discuss exotoxins

A

Exotoxins are produced inside mostly gram-positive bacteria as part of their growth and metabolism. They are then secreted or released following lysis into the surrounding medium.

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18
Q

Discuss III toxins: A-B toxins

A

see pic

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19
Q

Discuss type I toxins: superantigens

A

Cause an intense immune response due to cytokine released by hosts

Fever, nausea, vomiting, diarrhea, shock, death

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20
Q

Discuss type II toxins

A

Membrane-disrupting toxins

Lyse host’s cells:
-makes protein channels in the plasma membrane (ex. leukocidins, hemolysins)

-disrupts phospholipid bilayer

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21
Q

Discuss endotoxins

A

Endotoxins are part of the outer portion of the cell wall of gram-negative bacteria. They are liberated when the bacteria die and the cell wall breaks apart

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22
Q

Discuss antiphagocytic factors and certain factors that prevent phagocytosis by the host’s phagocytic cells

A

Bacterial capsule: composed of same chemicals found in host’s body
slippery -> difficult for phagocytes to engulf the bacteria

Antiphagocytic chemicals
-some prevent fusion of lysosome and phagocytic vesicles
-Leukocidins directly destroy phagocytic white blood cells

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23
Q

What are some pathogenic properties of protozoa?

A

-presence of protozoa

-protozoan waste products may cause symptoms

-avoid host defenses by
-growing in phagocytes
-antigenic variation

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24
Q

What are some pathogenic properties of fungi?

A

-fungal waste products may cause symptoms

-chronic infections provoke an allergic response

-mycotoxins

-capsule prevents phagocytosis

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25
Q

What are some pathogenic properties of helminths?

A

-use host tissue
-presence of parasite interferes with host function
-parasite’s metabolic waste can cause symptoms

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26
Q

What are some pathogenic properties of algae?

A

-Neurotoxins produced by dinoflagellates
-saxitoxin: paralytic shellfish poisoning

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27
Q

What are the mechanisms of pathogenicity?

A

see pic

portals of entry [number of invading microbes and adherence] -> penetration or evasion of host defenses -> damage to host cells/cytopathic effects -> portals of exit

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28
Q

What is pathology?

A

study of disease

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29
Q

What is the development of disease?

A

Pathogenesis

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30
Q

What is the study of the cause of a disease?

A

etiology

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31
Q

What is the colonization of the body by pathogens?

A

Infection

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32
Q

What is an abnormal state in which the body is not functionally normally?

A

Disease

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33
Q

What is transient microbiota?

A

-Present for hours, days, weeks, or months

-Cannot persist in the body
- competition from other microorganisms
- elimination by the body’s defenses cells
-chemical or physical changes in the body

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34
Q

What is normal microbiota?

A

permanently colonize the host

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35
Q

What is symbiosis?

A

Close, long-termed reactions between two organisms

[microbiota]

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36
Q

What is commensalism?

A

One organism is benefited and the other is unaffected

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37
Q

What is mutualism?

A

Both organisms benefit

38
Q

What is parasitism?

A

One organism is benefited at the expense of the other

39
Q

How does the normal microbiota protect the host by?

A

Occupying niches that pathogens might occupy

Producing acids

Producing bacteriocins

40
Q

What are probiotics?

A

Live microbes applied to or ingested into the body, intended to exert a beneficial effect

41
Q

Are some normal microbiota opportunistic pathogens?

A

Yes

42
Q

What is microbial anatgonism?

A

Competition between microbes

43
Q

What are the locations of normal microbiota in humans?

A

Nose and throat (upper respiratory system)

eyes

mouth

skin

large intestine

urinary and genital systems

44
Q

What are resident microbiota?

A

see pic

45
Q

What are opportunistic pathogens?

A

Normal microbiota that can cause disease under certain circumstances

46
Q

What are the conditions that provide opportunities for pathogens?

A

Immune suppression

Changes in the normal microbiota - changes in relative abundance of normal microbiota may allow opportunity for a member to thrive and cause disease

Introduction of normal microbiota into unusual site in the body

47
Q

What is contamination?

A

The mere presence of microbes in or on the body

47
Q

What is an infection?

A

An organism has evaded the body’s external defenses, multiplied, and become established in the body

48
Q

What are portals of entry and what are the four major types?

A

Sites through which pathogens enter the body

4 major types:
-skin
-mucous membranes
-placenta
-parenteral route

48
Q

How is skin a portal of entry?

A

Outer layer of packed, dead, skin cells

Usually = a barrier to pathogens

Pathogens can enter (1) through openings or cuts, (2) some can burrow into or digest the outer layers of skin

49
Q

How is a mucous membrane a portal of entry?

A

Line the body cavities that are open to the environment

Provides a moist, warm environment

Respiratory tract is the most commonly used site of entry (entry is through the nose, mouth, or eyes)

Gastrointestinal tract can be a route of entry
-pathogen must be able to survive the acidic pH of the stomach

50
Q

How is a parenteral route a portal of entry?

A

Not a true portal of entry, via injection or insertion

Pathogens deposited directly into tissues beneath the skin or mucous membranes

51
Q

Discuss pathogenic organisms

A

Portal of entry

Attachment or adhesion to cause infection (bacteria, viruses, and protozoa (parasites))

Infection - the invasion of the host by a pathogen

Disease - results only if the invading pathogen alters the normal functions of the body, also referred to as morbidity

52
Q

What are Koch’s postulates?

A
  1. The suspected germ must be present in every case of the disease
  2. The germ must be isolated and grown in pure culture
  3. The cultured germ must cause the disease when it is inoculated into a healthy, susceptible experimental host (animal or plant
  4. The same germ must be reisolated from the diseased experimental host
53
Q

What are the exceptions to Koch’s postulates?

A

Some pathogens can’t be cultured in the laboratory

Some diseases are caused by a combination of pathogens and other cofactors

Ethical considerations prevent applying to pathogens that require human host

Difficuluties:
-Diseases that can be caused by more than one pathogen
-Pathogens that are ignored as potential causes of disease

54
Q

What is a symptom?

A

A change in body function that is felt by a patient as a result of disease

54
Q

What is a syndrome?

A

A specific group of signs and symptoms that accompany a disease

54
Q

What is a sign?

A

A change in a body that can be measured or observed as a result of disease

55
Q

What is a communicable disease?

A

A disease that is spread from one host to another

56
Q

What is a contagious disease?

A

A communicable disease that is easily spread

57
Q

What is a non-communicable disease?

A

A disease that is not transmitted from one host to another

58
Q

What is an acute disease?

A

Symptoms develop rapidly

59
Q

What is a chronic disease?

A

Disease develops slowly

60
Q

What is a subacute disease?

A

Symptoms between acute and chronic

61
Q

What is a latent disease?

A

Disease with a period of no symptoms when the patient is inactive

62
Q

What is a local infection?

A

Pathogens limited to a small area of the body

63
Q

What is a systemic infection?

A

An infection throughout the body

64
Q

What is a focal infection?

A

Systemic infection that began as a local infection

65
Q

What is a bacteremia?

A

Bacteria in the blood

66
Q

What is a septicemia?

A

Growth of bacteria in the blood

67
Q

What is toxemia?

A

Toxins in the blood

68
Q

What is viremia?

A

Viruses in the blood

69
Q

What is a primary infection?

A

Acute infection that causes the initial illness

70
Q

What is a secondary infection?

A

Opportunistic infection after a primary (predisposing) infection

71
Q

What are some predisposing factors that make the body more susceptible to disease?

A

inherited traits such as sickle-cell gene

climate and weather

fatigue

age

lifestyle

short urethra in female

chemotherapy

72
Q

What is a subclinical disease?

A

No noticeable signs or symptoms (inapparent infection)

73
Q

What are the stages of infectious disease aka disease process?

A
  1. incubation period (no signs or symptoms)

2.prodromal period (vague, general symptoms)

  1. Illness (most severe signs and symptoms)
  2. Decline (declining signs and symptoms)
  3. Convalescence (no signs or symptoms)
74
Q

How do pathogens leave through the portals of exit?

A

Ear (wax)

Broken skin (blood)

Skin (flakes)

Anus (feces)

seminal vesicles (semen and secretions)

urethra (urine)

vagina (secretions, blood)

mammary glands (milk, secretions)

mouth (saliva, sputum)

nose (secretions)

eyes (tears)

75
Q

What are reservoirs of infection and some examples in humans, animals, and the nonliving?

A

They are continual sources of infection.

Humans - AIDS, gonorrhea
-carriers may have inapparent infections or latent diseases

Animal - rabies, lyme disease
-some zoonoses may be transmitted to humans

Nonliving - botulism, tetanus
-soil

76
Q

What are the transmission of disease through contact?

A

Direct contact: requires close association between infected and susceptible host

Indirect contact: spread by fomites

Droplet transmission via airborne droplets

77
Q

What are the transmission of disease via vehicle and vector?

A

Vehicles: transmission by an inanimate reservoir (food, water)

Vectors: arthropods, especially fleas, ticks, and mosquitoes
-mechanical arthropod carries pathogen on feet
-biological pathogen reproduces in vector

78
Q

What are nosocomial infections?

A

Are acquired as a result of a hospital stay

5-15% of all hospital patients acquire nosocomial infections

79
Q

What are emerging new diseases and contributing factors?

A

Evolution of new strains; ex v. cholera O139

Inappropriate use of antibiotics and pesticides: antibiotic resistant strains

Changes in weather patterns: Hantavirus

Modern transportation: West Nile virus

Ecological disaster, war, expanding human settlement: Coccidioidomycosis

Animal control measures: Lyme disease

Public health failure: diphtheria

80
Q

What is epidemiology?

A

The study of where and when diseases occur and how they are transmitted in a population

81
Q

During the occurrence of disease, what is incidence?

A

Fraction of a population that contracts a disease during a specific time period

82
Q

During the occurrence of disease, what is prevalence?

A

Fraction of a population having a specific disease at a given time

83
Q

What is endemic disease?

A

Disease constantly present in a population

Disease acquired by many hosts in a given area in a short time

83
Q

What is a sporadic disease?

A

Disease that occurs occasionally in a population

84
Q

What is morbidity?

A

Incidence of a specific notifiable disease

84
Q

What is a pandemic disease?

A

Worldwide epidemic

84
Q

What is mortality?

A

deaths from notifiable disease

Microbiology (17 decks)

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