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General Microbiology > Infection and Pathogenicity > Flashcards

Infection and Pathogenicity Flashcards

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1
Q

General Infection Terms

host

A

larger organism that supports the survival and growth of a smaller organism

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2
Q

General Infection Terms

infection

A

a microbe growing and multiplying on or within a host

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3
Q

T/F: All infections will result in an overt infectious disease.

A

FALSE – infection may or may not result in overt infectious disease

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4
Q

General Infection Terms

infectious disease

A

any change from a state of health
- part or all of the host is incapable of carrying on normal functions due to presence of a pathogen or its products

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5
Q

General Infection Terms

pathogen

A

any organism that causes disease

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6
Q

General Infection Terms

opportunistic pathogen

A

may be part of normal flora and causes disease when it gains access to other tissue sites or when the host is immunocompromised

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7
Q

General Infection Terms

pathogenicity

A

ability of a pathogen to cause disease

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8
Q

General Infection Terms

virulence

A

degree of harm (pathogenicity) inflicted on the host

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9
Q

Types of Microorganisms

extracelllular pathogens
- example?

A

remain in tissues and fluids and do not enter host cells during the course of disease
- yersinia pestis causes plaque (black death)

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10
Q

Types of Microorganisms

intracellular bacteria

A

grow and multiply within host cells

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11
Q

Types of Microorganisms

What are the two types of intracellular bacteria?

A
  • facultative intracellular pathogens
  • obligate intracellular pathogens
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12
Q

Types of Microorganisms

facultative intracelluar pathogens
- example?

A

reside within host cells but can also grow in the environment
- listeria monocytogenes

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13
Q

Types of Microorganisms

obligate intracellular pathogens

A

cannot replicate outside a host cell

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14
Q

T/F: All viruses are obligate intracellular pathogens.

A

TRUE

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15
Q

T/F: Bacteria such as chlamydia spp. and Rickettsia can not be cultured outside of host cells.

A

TRUE

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16
Q

T/F: Malarial parasites are protzoa that require host cells for growth.

A

TRUE

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17
Q

Course of Infectious Disease

What are the general phases in infection?

A
  • incubation period
  • prodromal stage
  • illness period
  • convalescence
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18
Q

Course of Infectious Disease

incubation period

A

period after pathogen entry; before signs and symptoms

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19
Q

Course of Infectious Disease

prodromal stage

A
  • onset of signs and symptoms
  • not clear enough for diagnosis
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20
Q

Course of Infectious Disease

illness period

A

disease is most severe; characteristic signs and symptoms

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21
Q

Course of Infectious Disease

convalescence

A

signs and symptoms begin to disappear

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22
Q

Course of Infectious Disease Terms

signs

A
  • objective changes in the body that can be directly observed
  • fever, rash, vomitting
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23
Q

Course of Infectious Disease Terms

symptoms

A
  • subjective changes experienced by patient
  • pain, loss of appetite
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24
Q

Course of Infectious Disease Terms

disease syndrome

A

set of characteristic signs and symptoms for a disease

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25
Q

Events in Infection and Disease

First step?

A

transmission from previous host or resevour to new host

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26
Q

What 3 factors affect the success of transmission?

A
  1. virulence of organism
  2. number of invading organisms
  3. presence of adhesion and invasion factors
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27
Q

Events in Infection and Disease

Second step?

A

organism outcompetes the resident microbiota for resources and survives host defense mechanisms

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28
Q

Course of Infectious Disease

Third step?

A

disease occurs when organism produces molecules that directly damage host cells OR stimulates host immune cells to destroy infected tissue OR alters the host cell genome affecting normal function

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29
Q

Sources of Pathogens

What are examples of animate sources of pathogens?

A

humans or other animals

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30
Q

Sources of Pathogens

What are examples of inanimate sources of pathogens?

A

water or food

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31
Q

Sources of Pathogens

reservoir

A

natural environmental location in which the pathogen normally resides

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32
Q

Sources of Pathogens

zoonoses

A

when an infectious agent is transmitted from an animal to a human

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33
Q

Sources of Pathogens

vector

A

organism that spread disease from one host to another
- mosquitoes, ticks, fleas, mites, or biting flies

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34
Q

Pathogen Transmission

T/F: Pathogen transmission occurs either directly or indirectly.

A

TRUE

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35
Q

Pathogen Transmission

What are the 4 main routes of pathogen transmission?

A
  • airborne
  • contact
  • vehicle
  • vector-borne
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36
Q

Pathogen Transmission

What type of transmission only pregnant women are capable of?

A

vertical transmission

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37
Q

Transmission and Virulence

T/F: Pathogen’s virulence may be strongly influenced by its mode of transmission and ability to live outside its host.

A

TRUE

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38
Q

Transmission and Virulence

T/F: Transmission alone is not enough for infection to occur.

A

TRUE – tropism

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39
Q

Transmission and Virulence

tropism

A

pathogen must make contact with appropriate host tissue; determined by specific cell surface receptors

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40
Q

Airborne Transmission

What are the 3 kinds of airborne transmission?

A
  • droplets
  • droplet nuclei
  • dust particles
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41
Q

Airborne Transmission: Droplets

Indirect or direct?

A

direct transmission

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42
Q

Airborne Transmission: Droplets

Diameter size?

A

up to 2 mm in diameter

43
Q

Airborne Transmission: Droplets

How are droplets produced?

A

when liquids are placed under force
- sneezing, coughing

44
Q

Airborne Transmission: Droplets

Travel distance?

A

can travel < 1 m

45
Q

Airborne Transmission: Droplet Nuclei

Diameter size?

A

1 to 5 micrometers

46
Q

Airborne Transmission: Droplet Nuclei

How are droplet nuclei produced?

A

result from evaporation of the larger droplets

47
Q

Airborne Transmission: Droplet Nuclei

How long do they stay airborne?

A

may remain airborne for hours or days and travel long distances

48
Q

Airborne Transmission: Dust Particles

Indirect or direct?

A

indirect

49
Q

Airborne Transmission: Dust Particles

Describe transmitting dust particles.

A

microorganisms adhere to dust particles

50
Q

Airborne Transmission: Dust Particles

T/F: If microorganisms can survive long periods outside host, it can lead to infection.

A

TRUE

51
Q

Contact Transmission

contact transmission

A

coming together or touching of source/reservoir and host

52
Q

Contact Transmission

Direct contact

A
  • “person to person”
  • physical interaction between source/reservoir and host
  • kissing, touching, and sexual contact
53
Q

Contact Transmission

indirect contact

A
  • involves an inanimate object (fomite)
  • eating utensils, bedding
54
Q

Vehicle Transmission

vehicles

A

inanimate materials that transmit pathogens
- food, water, biological materials, air

55
Q

Vehicle Transmission

How effective is vehicle transmission?

A

single vehicle spreads a pathogen to multiple hosts

56
Q

Vector-Borne Transmission

vector

A

direct living transmitter of a pathogen
- most are arthropods (insects, ticks, mites, fleas) or vertebrates (dogs, cats, skunks, bats)

57
Q

Vector-Borne Transmission

Pathogens transmitted by arthropods are often ?? ??.

A

highly virulent

58
Q

Vector-Borne Transmission

T/F: Pathogens harm their vectors.

A

FALSE – it is highly important that pathgoens do not harm their vectors

59
Q

Vertical Transmission

vertical transmission

A

occurs when the unborn chold acquires a pathogen from an infected mother

60
Q

Vertical Transmission

T/F: Vertical transmission and horizontal transmission are equally as common.

A

FALSE – vertical transmission is not as common as horizontal transmission

61
Q

Vertical Transmission

Babies born with an infectious disease are said to have a ?? ??.

A

congenital infection
- gonorrhea, syphilis, herpes, german measles, toxoplasmosis

62
Q

The rate at which an infection proceeds and severity directly correlate with the “??”, “??”, and “??”.

A
  • inital inoculum of microorgansisms
  • their virulence
  • the host’s ability to combat infection
63
Q

What are things contribute to a host susceptibilty?

A
  • poor nutrition
  • stress
  • genetics
  • immunocompromised
64
Q

LD50 vs. ID50

Infectious dose 50 (ID50)

A

the number of microorganisms required to cause disease in 50% of the inoculated hosts

65
Q

LD50 vs. ID50

The lower the infectious dose …

A

the higher the risk of infection

66
Q

LD50 vs. ID50

Lethal Dose 50 (LD50)

A

the number of microorganisms required to be lethal to 50% of the inoculated hosts

67
Q

LD50 vs. ID50

Highly virulent pathogens kill at a ?? than less viruleent organisms.

A

lower dose

68
Q

Adherence and Colonization

What are the first steps of any disease?

A

entry and attachment

69
Q

Adherence and Colonization

Examples of portal of entry.

A
  • skin
  • respiratory
  • GI
  • urogenital systems
  • conjuctiva of the eye
70
Q

Adherence and Colonization

adherence

A

mediated by special molecules called adhesions
- pili, capsules

71
Q

Adherence and Colonization

colonization

A
  • site of microbial replication on or within a host
  • does not necessarily result in tissue invasion or damage
72
Q

Invasion DIsseminates Pathogens

infectivity

A

ability to create a discrete point of infection

73
Q

Invasion DIsseminates Pathogens

Invasiveness

A

ability to spread to adjacent tissues

74
Q

Invasion DIsseminates Pathogens

Active Penetration

A

occurs through lytic substances that alter host tissue:

  • attacking the ECM and basement membranes of integuments and intestinal linings
  • degrading carbohydrate-protein complexes between cells or on the cell surface
  • disrupting the host cell surface
75
Q

Invasion DIsseminates Pathogens

Passive penetration

A

not related to the pathogen itself
- skin lesions, insect bites, wounds

76
Q

Pathogen Dissemination

bacteremia

A

presence of viable bacteria in the bloodstream

76
Q

Pathogens Dissemination

septicemia

A

presence of bacterial or fungal toxins in the bloodstream

77
Q

Overcoming Host Defenses

T/F: Most microbes eliminated before they can cause disease due to immune system.

A

TRUE

78
Q

Overcoming Host Defenses

How do pathogens overcome host defenses?

A
  • produce Type III and IV secretion system
  • find shelter to avoid recognition by defense cells
  • survive and replicate inside host cells
  • squeeze between host cells
  • make capsules to avoid phagocytosis
  • burrow under mucus
  • secrete exopolysaccharides to form communal shelters within biofilms
  • produce enzymes that inactivate innate resistance mechanisms
  • excrete specialized proteins to selectively kill host cells
79
Q

Biofilms

What are biofilm bacteria protected from?

A
  • nutrient deprivation
  • predators
  • environmental shifts
  • antimicrobial agents
  • host immune cells
80
Q

Biofilms

Some pathogenic bacteria within biofilms exchange ??, ??, and ??, altering their behavior.

A
  • plasmids
  • nutrients
  • quorum-sensing
81
Q

Biofilms

How do these bacteria information exchange interactions affect the bacteria when it comes to survival?

A
  • less sensitive to antibiotics
  • more resistant to host defense mechanisms
82
Q

Pathogenicity Islands

Large segments of bacterial chromosomal and plasmid DNA was found to encode what?

A

virulence factors

83
Q

Pathogenicity Islands

The large encoding segments ?? bacterial virulence.

A

increase

84
Q

Pathogenicity Islands

The large encoding segments are ?? in nonpathgenic members of same genus or species.

A

absent

85
Q

Pathogenicity Islands

Large encoding segments can be spread through ?? transfer of ?? to bacteria.

A
  • horizontal
  • virulence genes
86
Q

Toxigenicity

What does it mean when microbes possess toxigenicity?

A

ability to produce toxins

87
Q

Toxigenicity

toxin

A

specific substance that damages host

88
Q

Toxigenicity

intoxications

A

diseases that result from entry of a specific preformed toxin into host

89
Q

Exotoxins

exotoxins

A

soluble, heat-liable proteins

90
Q

Exotoxins

Exotoxins are ?? into surroundings as pathogen metabolizes.

A

secreted

91
Q

Exotoxins

T/F: Exotoxins often travel from site of infection to other tissues or cells where they exert their effects.

A

TRUE

92
Q

Exotoxins

T/F: All exotoxins are made by any bacteria.

A

FALSE - exotoxins are usually synthesized by specific bacteria that have toxin genes in their plasmids or prophage DNA

93
Q

Exotoxins

T/F: Exotoxins among the most lethal substances known.

A

TRUE

94
Q

Types of Exotoxins

AB Toxins

A

composed of two subunits:
- A subunit: responsible for toxic effect
- B subunit: binds to specific target cell

(cholera toxin, diphtheria toxin)

95
Q

Types of Exotoxins

Membrane-disrupting exotoxins

A

hemolysins

96
Q

Superantigens

Stimulate about ?? of T cells of the immune system.

A

30%

97
Q

Superantigens

What do superantigens causes T cells to do?

A

overexpress and release pro-inflammatory cytokines

98
Q

Superantigens

T cell stimulation by superantigens typically results in?

A

failure of multiple host organs allowing time for the microbe to disseminate

99
Q

Endotoxin-Lipopolysaccharide

What can LPS in gram-negative cell walls be to specific hosts?

A

toxic

100
Q

Endotoxin-Lipopolysaccharide

Why are LPSs considered endotoxins?

A

they are bound to the bacterium and released when the microorganism lyses; some is also released during multiplication

101
Q

Endotoxin-Lipopolysaccharide

What portion of of the LPS is the toxic component?

A

the lipid portion; lipid A

102
Q

Endotoxins-General Feature

General features of endotoxins.

A
  • heat stable
  • toxic (nanogram amounts)
  • weakly immunogenic
  • generally similar, despite source
103
Q

Endotoxins-General Feature

What are general system effects of endotoxins?

A
  • fever
  • shock
  • damage to the lining of blood vessels
  • weakness
  • diarrhea
  • inflammation
  • intestinal hemorrhage
  • fibrinolysis

General Microbiology (11 decks)

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