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Microbiology > Chapter 14: Infection, Infectious Diseases, and Epidemiology > Flashcards

Chapter 14: Infection, Infectious Diseases, and Epidemiology Flashcards

1
Q

Symbiosis

A

-living life together

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2
Q

Mutalism

A

-organism 1 and organism 2 benefits
ex: bacteria living in human colon

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3
Q

commensalism

A

-organism 1 benefits and organism 2 is not harmed nor benefiting
ex: mites in human hair follicles

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4
Q

amensalism

A

organism 1 is harmed, while organism 2 is neither harmed nor benefitting
ex: fungus secreting an antibiotic inhabiting bacteria nearby

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5
Q

parasitism

A

organism 1 benefits, while organism 2 is harmed
ex: tuberculosis bacteria in human lung

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6
Q

axenic

A

-free of microbes
ex: some parts of the body are this like the womb

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7
Q

How and when do you acquire normal flora if the womb is axenic?

A

-babies acquire their own flora at birth, moving through the birth canal but it is established at 3-6 months

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8
Q

What are normal/Indigenous microbiota or flora

A

-organisms that colonize the body’s surfaces without normally causing diseases
-most are harmless, but can be opportunistic

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9
Q

resident microbiota

A

-most are commensal, The microorganisms that usually live on or in a particular body site

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10
Q

transient microbiota

A

-microbes that get into normal microbiota and are visitors, eventually removed

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11
Q

What are the three main reasons transient microbes cannot persist in your body?

A
  1. competition from other microorganisms
  2. elimination by the body’s defenses cells
  3. chemical or physical/physiological changes in the body
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12
Q

Opportunists

A

-take advantage of certain situations

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13
Q

How can you inquire an opportunistic infection?

A
  1. Introduction of normal microbiota into unusual site in the body (E.coli helpful in gut, can cause UTI)
  2. Immune suppression: temporary or chronic
  3. changes in the normal microbiota which changes the antagonism or competition
  4. Disruption of your normal microbiota as a result of stressful conditions
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14
Q

Reservoirs of Infection

A

-most pathogens cannot survive long outside of their host
-sites where pathogens are maintained as a source of infection
-think of microbial reservoirs as places of stored pathogens

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15
Q

What are the three types of reservoirs which can be sites of microbial contamination?

A
  1. animals reservoirs (both sylvatic or domesticated)
  2. human carriers
  3. non-living reservoirs
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16
Q

Zoonoses (zoonotic diseases)

A

are ones that are naturally spread from their usual animal host to humans but not usually the other way around
ex: rabies, anthrax, bubonic plague
-humans are often dead end host to zoonotic pathogens as they do not transmit the infection

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17
Q

What routes do we acquire zoonoses

A

1.direct contact with an animal or its waste
2. eating infected animal or animal products
3. bloodsucking arthropods acting as vectors

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18
Q

Human carriers

A

infected individuals who are asymptomatic but infective to others
-some individuals will eventually develop the illness while others never get sick
-healthy carriers may have a defensive system that protects them from illness but do not clear entirely from host (Typhoid Mary)

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19
Q

Non-living reservoirs

A

-soil, water, food can store infection
-the presence of microorganisms is often due to contamination by feces or urine

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20
Q

contamination

A

the mere presence of microbes in or on the body

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21
Q

Infection

A

is when the organism have evaded the body’s external defenses, multiplied and become established in the body
-they may or may not cause disease

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22
Q

How do pathogens infect and subsequently leave the body?

A

-they need a portal of entry or exit
ex: mouth, nose, ears, urethra, vagina, anus, nipples, eyes

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23
Q

Methods of entry: skin

A

as an outer layer of packed, dead, skin cells which usually act as a very effective barrier to pathogens
-some enter through cuts or burrowing into or digesting the skin

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24
Q

mucous membrane

A

lines the body cavities to protect are the most common portals of entry

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25
Q

Why do pathogens like mucous membranes?

A

-they like the moisture, nutrients, and temperature

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26
Q

What is the most commonly used site of entry

A

respiratory tract (nose, mouth, eyes)
*if they can survive the acidic pH of the stomach may use the GI tract as entry

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27
Q

parenteral route

A

-not a true portal of entry but a means by which they can be circumvented when a pathogen is deposited directly into tissue beneath the skin or mucous membrane
ex: catheters
* another portal of entrance is placenta

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28
Q

Treponema pallidum

A

-causes syphilis in adults
- can cause abortions, syphilis, and multiorgan birth defects in fetus

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29
Q

Toxoplasma gondii

A

-causes toxoplasmosis in adults
-in fetus can cause abortion, anemia, blindness, epilepsy, deafness

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30
Q

Lentivirus (HIV)

A

-causes AIDS in adults
-in fetus causes immunosuppression (AIDS)

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30
Q

Listeria monocytogenes

A

-causes listeria in adults
-in fetus granulomatosis infantiseptica

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31
Q

Adhesion/ Attachment

A

the process by which microorganisms attaches themselves to cells or surfaces
-adhesion is required by microbes to successfully establish colonies within the organism

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32
Q

What are some adhesion factors

A
  1. specialized structures (fimbria, hooks, adhesion discs)
  2. lipoproteins or glycoproteins attach onto organisms cell surface acting as ligands that allow them to attach specifically to complementary receptors on other cells
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33
Q

Attachment proteins (adhesions)

A

-found on viruses and bacteria, are lipoproteins or glycoproteins acting as ligands to specifically bind to host cell receptors
-interaction of a ligand with the host receptor can determine specificity for host cells
-some microbes adhere to other bacteria by biofilms

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34
Q

What can make microorganisms avirulent?

A

the ability to change or block the ligand or the receptor can prevent infection, making it unstable for the microbe to attach thereby making it avirulent

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35
Q

What is an example of an infection?

A

-the invasion and establishment by a pathogen within a host

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36
Q

Disease

A

results only if a pathogen alters the normal function of the body (a change of health)
-also referred to as morbidity

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37
Q

Syndrome

A

a group of symptoms and signs that characterize a disease or abnormal condition

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38
Q

asymptomatic/subclinical

A

may still be able to detect signs of some infections even when asymptomatic as in HIV

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39
Q

symptom

A

only the person can feel it, no one else can see it (subjective)
ex: nauseous, fatigue, dizzy

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40
Q

sign

A

something that can be seen, quantified or measured by someone else
ex: throwing up, fever, swelling,

41
Q

etiology

A

study of the cause of disease
-some disease are hereditary and others are congenital (born with it)

42
Q

Who proposed the germ theory of diseases

A
  • Koch and Pasteur
43
Q

What was the germ theory of diseases

A

-the germ theory determined that some diseases are caused by infections of pathogenic microorganisms

44
Q

How do we prove/determine that a particular microbe causes disease?

A

-Koch postulates

45
Q

Exceptions to Koch postulates

A

-some pathogens cannot be cultured in the lab (M leprae, Bartonella)
-some diseases are caused by a combination of pathogens or other cofactors (ex: Liver cancer)
-ethical considerations prevent applying this to pathogens that require human host
-some diseases can be caused by more than one pathogen (pneumonia, hepatitis, meningitis

46
Q

pathogenicity

A

ability of a microbe to cause disease

47
Q

virulence

A

the degree of pathogenicity

48
Q

What factors contribute to virulence

A
  1. adhesion factors (capsules, biofilms)
  2. extracellular enzymes (Kinases (streptokinase and staphylokinase), coagulase, hyaluronidase, collagenase)
49
Q

toxins

A

-cause toxemia

50
Q

exotoxins

A
  • cytotoxins, neurotoxins, or enterotoxins
    1. bacteria secrete exotoxins in this case a cytotoxin
    2. cytotoxin kills host cells
51
Q

endotoxin

A

-in gram negative bacteria
-dead gram negative bacteria release an endotoxin (Lipid A) which induces effects like fever, inflammation, shock, blood coagulation , diarrhea

52
Q

which molecules in us may be used as antitoxins?

A

antibiotics

53
Q

toxoid

A

chewed up part of a toxin that provides artificial active immunity when injected in a person

54
Q

Hyaluronidase and collagenase

A

-these are extracellular enzymes
1. invasive bacteria reaches the epithelial surface
2. Bacteria produced hyaluronidase and collagenase
3. bacteria invade deeper tissue

55
Q

coagulase and kinases

A

-these are extracellular enzymes
1. bacteria produces coagulase
2. clot forms
3. bacteria later produce kinase, dissolving clot and releasing bacteria

56
Q

Exotoxins source

A

mostly gram positive and gram negative

57
Q

exotoxins relation to bacteria

A

-metabolic product secreted from living cell

58
Q

exotoxins chemical nature

A

protein or short peptide

59
Q

exotoxins toxicity

A

high

60
Q

exotoxins heat stability

A

typically unstable in temp above 60 C

61
Q

exotoxins effect on host

A

-variable depending on source may be cytotoxin, neurotoxin, and enterotoxin
-does not produce fever

62
Q

exotoxins antigenicity

A

strong stimulus antitoxin (antibody protection)

63
Q

endotoxin source

A

gram negative bacteria

64
Q

endotoxin relation to bacteria

A

-portion of outer cell (cell wall) membrane released upon cell wall

65
Q

endotoxin chemical nature

A

lipid portion of lipopolysaccharide (lipid A) of outer cell wall membrane

66
Q

endotoxin toxicity

A

low, but may be fatal in high doses

67
Q

endotoxin heat stability

A

stable for up to an 1hr at autoclave temperature

68
Q

endotoxin effect on host

A

-fever, lethargy, malaise, shock, blood coagulation
-does cause fever

69
Q

diseases of endotoxin

A

-typhoid fever, endotoxin shock, urinary tract infections, meningococcal meningitis

70
Q

diseases of exotoxins

A

-botulism, tetanus, gangrene, diphtheria, cholera, plague, staphylococcal food poisoning

71
Q

Bacterial capsule

A

-this can prevent phagocytosis by host cell
-they are often composed of chemicals found in the body and not recognized in the immune system as foreign
-capsules can be slippery making it difficult for phagocytes to engulf bacteria

72
Q

antiphagocytic chemicals

A

-some prevent the fusion of the lysosome and the phagosome (phagocytic vesicle)

73
Q

Leukocidins

A

a bacteria will produce this and kill all white blood cells

74
Q

M proteins

A

help bacteria resist phagocytosis

75
Q

Stages of infectious disease

A

-many have five stages but some have only four
1. Incubation
2. Prodromal (not always present)
3. illness
4. decline
5. convalescence
*pathogens leave their host cells via exit portal

76
Q

Incubation

A

-low amount of microbes with no signs or symptoms

77
Q

prodromal

A

increase in microbes, no signs but symptoms

78
Q

illness

A

showing signs and symptoms, peak microbes

79
Q

decline

A

microbes declining

80
Q

convalescence

A

-repair state

81
Q

Modes of disease transmission

A

contact
-direct, indirect, droplet transmission

vehicle
-airborne, waterborne, foodborne

vector
-mechanical (bodies of flies, roaches), biological ( mites, lice, ticks)

82
Q

How do we classify infectious diseases

A
  1. The body system they affect (urinary, respiratory)
  2. the taxonomic groups of the causative agent
  3. their longevity and severity (acute, chronic, subacute, latent, asymptomatic)
  4. how they spread to their host or source (communicable, contagious, secondary, systemic, focal)
83
Q

epidemiology

A

the study of the where and when diseases occur and how they are transmitted and/or prevented within populations
-tracks the occurrence as a frequency of diseases using two measure
1. incidence
2. prevalence
-occurrence is also evaluated in terms of frequency and geographic distribution (endemic vs epidemic, pandemic vs sporadic

84
Q

incidence

A

-number of new causes of a disease in a given area during a given period of time

85
Q

prevalence

A

-number of total cases of a disease in a given area during a give period of time

86
Q

endemic disease

A

-not going away
ex: flu, sars covid 2

87
Q

epidemic disease

A

break out somewhere

88
Q

pandemic disease

A
  • higher than normal in more than two continents
89
Q

How to epidemiologists study diseases

A
  1. descriptive
  2. analytical
  3. experimental
90
Q

descriptive

A

tabulation of data concerning a disease
-record of information about the location and time of the cases of diseases and collect patient information
-try to identify the index case (first case) of the disease

91
Q

analytical

A

-determine the probable cause mode of transmission and methods of prevention
-useful when koch’s postulate cannot be applied
-often retrospective = investigate after outbreak

92
Q

experimental

A

-testing a hypothesis concerning the causative agent of a disease, as in applying Koch’s postulates or studies from analytical data

93
Q

Nosocomial “HAI Infection”

A

-health care acquired infection

94
Q

Exogenous

A

-pathogen acquired from the health care environment, such as from a patient or the facility

95
Q

endogenous

A

pathogen arise from normal microbiota

96
Q

latrogenic

A

results from modern medical procedures

97
Q

How to control HAI

A

-use precautions (PPE, gloves, antiseptics/sanitizers, designed to reduce the factors that result in disease)

98
Q

Public health and epidemiology

A

-data collected by local practitioners, city, county, and state health departments sent to the CDC
-the United States Public Health Service is the national public health agency
-WHO coordinates public health services internationally

99
Q

public health agencies try to limit transmission by?

A
  1. monitoring water and food safety and enforce standards
  2. public health agencies educate the public on healthful choices to limit diseases

Microbiology (13 decks)

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