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Microbiology > Ch. 23 > Flashcards

Ch. 23 Flashcards

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Biology 101 flashcards
1
Q

Most microorganisms are ___.

A

Benign

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2
Q

Humans are colonized by ___ at birth.

A

Microorganisms

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3
Q

Microorganisms usually found associated with human ___ ___.

A

Body tissue

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4
Q

Pathogens -

A

Microbial parasites

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5
Q

Pathogenicity -

A

The ability of a parasite to inflict damage on the host (cause disease)

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6
Q

Virulence -

A

Measure of pathogenicity (attachment structures, enzymes, toxins)

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7
Q

Opportunistic pathogen -

A

Causes disease only in the absence of normal host resistance

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8
Q

Infection -

A

Situation in which a microorganism is established and growing in a host, whether or not the host is harmed

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9
Q

Disease -

A

Damage or injury to the host that impairs host function

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10
Q

___ provide a favorable environment for the growth of many microorganisms.

A

Animals

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11
Q

Infections frequently begin at sites in the animals ___ ___.

A

Mucous membranes

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12
Q

The ___ surface varies greatly in chemical composition and moisture content.

A

Skin

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13
Q

Skin

Three microenvironments:

A
  • dry skin
  • moist skin
  • sebaceous skin
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14
Q

Dry skin:

A

Forearms and palms of hands

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15
Q

Moist skin:

A

Inside of nostrils, armpits, umbilicus

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16
Q

Sebaceous skin

A

Side of the nose, back of scalp, upper chest and back

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17
Q

Skin microflora examined by molecular ___ methods.

A

Ecology

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18
Q

Skin microflora examined by molecular ecology methods.

How many phyla detected?

A

19

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19
Q

Each microenvironment shows a unique ___.

A

Microbiota

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20
Q

The skin microflora

Composition is influenced by:

A
  • environmental factors

- host factors

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21
Q

The ___ ___ is a complex, heterogeneous microbial habitat.

A

Oral cavity

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22
Q

Saliva contains ___ enzymes.

A

Antimicrobial

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23
Q

High concentrations of nutrients near surfaces in the mouth promote what?

A

Localized microbial growth

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24
Q

The ___ consists of a mineral matrix surrounding living tissue.

A

Tooth

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25
Q

Enamel -

A

Mineral matrix in teeth

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26
Q

Dentin and pulp -

A

Living tissue in teeth

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27
Q

How do bacteria colonize tooth surfaces?

A

Bacteria colonize tooth surfaces by first attaching to acidic glycoproteins there by saliva.

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28
Q

___ analysis of human microflora shows a complex microbial community.

A

Metagenomic

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29
Q

Human microflora

A
  • most microorganisms are facultatively aerobic
  • some are obligately anaerobic
  • some are obligately aerobic
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30
Q

The human gastrointestinal (GI) tract consists of:

A

Stomach, small intestine, and large intestine

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31
Q

What is the GI tract responsible for?

A

Digestion of food, absorption of nutrients, and production of nutrients by the indigenous microbial flora

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32
Q

The GI tract contains how many microbial cells?

A

10^13-10^14

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33
Q

Microbial populations in different areas of the GI tract are influenced by…

A

Diet and the physical conditions in the area

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34
Q

The ___ of the stomach and the duodenum of the small intestine prevents many organisms from colonizing the GI tract.

A

Acidity

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35
Q

Functions and products of intestinal flora.

Compounds produced include:

A
  • vitamins
  • gas, organic acids, and odor
  • enzymes
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36
Q

A restricted group of organisms colonizes the upper ___ ___.

A

Respiratory tract

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37
Q

Examples of organisms that colonize the upper respiratory tract:

A

Staphylococci, steptococci, diphtheroid, bacilli, and gram-negative cocci

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38
Q

Staphylococcus aureus and Streptococcus pneumoniae can be found in the __ of some healthy individuals.

A

Nasopharynx

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39
Q

The lower respiratory tract lacks microflora in ___individuals.

A

Healthy

40
Q

Upper respiratory tract:

A
  • sinuses
  • nasopharynx
  • pharynx
  • oral cavity
  • larynx
41
Q

Lower respiratory tract:

A
  • trachea
  • bronchi
  • lungs
42
Q

The ___ is typically sterile in both males and females.

A

Bladder

43
Q

Urogenital tract

Altered conditions (such as change in pH) can cause potential pathogens in the urethra (such as ___ ___ and ___ ___) to multiply and become pathogenic.

A

Escherichia coli and Proteus mirabillis

44
Q

E. coli and P. mirabilis frequently cause what in women?

A

Urinary tract infection

45
Q

The ___ of the adult female is weakly acidic and contains significant amounts of glycogen.

A

Vagina

46
Q

___ ___, a resident organism in the vagina, ferments the glycogen, producing lactic acid.

A

Lactobacillus acidophilus

47
Q

___ ___ maintains a local acidic environment.

A

Lactic acid

48
Q

What are pregnant women tested for?

A

Group B Strep

49
Q

Virulence can be estimated from experimental studies of the ___.

A

Lethal dose 50 (LD50)

50
Q

Lethal dose 50

A

The amount of an agent that kills 50% of the animals in a test group

51
Q

Highly virulent pathogens

A

Show little difference in the number of cells required to kill 100% of the population as compared to 50% of the population

52
Q

Attenuation -

A

The decrease or loss of virulence

53
Q

Toxicity -

A

Organism causes disease by means of a toxin that inhibits host cell function or kills host cells

54
Q

Exotoxins:

A

Cytotoxin
Neurotoxin
Enterotoxin

55
Q

___ can travel to sites within host not inhabited by pathogen.

A

Toxins

56
Q

Invasiveness -

A

Ability of a pathogen to grow in host tissue at densities that inhibit host function

57
Q

___ can cause damage without producing a toxin.

A

Invasiveness

58
Q

Many pathogens use a combination of toxins, invasiveness, and other virulence factors to enhance ___.

A

Pathogenicity

59
Q

Bacteria and viruses that initiate infection often adhere specifically to epithelial cells through what?

A

Interactions between molecules on the surfaces of the pathogen and the host cell

60
Q

Bacterial adherence can be facilitated by:

A
  • extracellular macromolecules that are not covalently attached to the bacterial cell surface (slime layer, capsule)
  • fimbriae and pili
61
Q

The ___ ___ of a pathogen is insufficient to cause host damage.

A

Initial inoculum

62
Q

The pathogen must multiple and colonize the ___.

A

Tissue

63
Q

What is most important in affecting pathogen growth?

A

Availability of nutrients

64
Q

Pathogens may grow locally at the site of invasion or may…

A

Spread throughout the body

65
Q

Bacteremia -

A

The presence of bacteria in the bloodstream

66
Q

Septicemia -

A

Bloodborne systematic infection

67
Q

Septicemia may lead to..

A

Massive inflammation, septic shock, and death

68
Q

Infection requires..

A

Attachment to surface as well as growth

69
Q

Attachment and growth have been well studied in the formation of ___ on tooth surfaces.

A

Biofilms

70
Q

Acidic ___ from saliva form a thin film.

A

Glycoproteins

71
Q

Streptococcus sobrinus and streptococcus mutans are common agents in __ __.

A

Tooth decay

72
Q

Dental plaque -

A

Extensive growth of oral microorganisms, especially streptococci, results in a thick bacterial layer

73
Q

As plaque continues to develop, ___ bacterial species begin to grow.

A

Anaerobic

74
Q

Dental caries -

A

As dental plaque accumulates, the microorganisms produce high concentrations of acid, resulting in decalcification of the tooth enamel

75
Q

Pathogens produce enzymes that:

A
  • enhance virulence by breaking down or altering host tissue to provide access to nutrients
  • protect the pathogen by interfering with normal host defense mechanisms
76
Q

Example of enzyme that enhances virulence by breaking down or altering host tissue to provide access to nutrients?

A

Hyaluronidase

77
Q

Example of enzyme that protects the pathogen by interfering with normal host defense mechanisms?

A

Coagulase

78
Q

___ species encode a large number of virulence factors.

A

Salmonella

79
Q

Salmonella also contains ___ plasmids.

A

Resistance (R plasmids)

80
Q

Several genes that direct invasion are clustered together on the chromosome as ___ ___.

A

Pathogenicity islands

81
Q

Three categories of exotoxins:

A

Cytotoxins
AB toxins
Superantigen toxins

82
Q

Exotoxins -

A

Proteins released from the pathogen cell as it grows

83
Q

Cytotoxins (cytolytic toxins) -

A

Work by degrading cytoplasmic membrane integrity, causing cell lysis and death

84
Q

Toxins that lyse red blood cells are called ___.

A

Hemolysins

85
Q

Staphylococcus alpha-toxin

A

Kills nucleated cells and lyses erythrocytes

86
Q

AB toxins

A
  • consist of two subunits, A and B
  • work by binding to a host cell receptor (B subunit) and transferring damaging agent (A subunit) across the cell membrane
87
Q

Examples of AB toxins

A
  • diphtheria toxin
  • tetanus toxin
  • botulinum toxin
88
Q

Clostridium tetani and clostridium botulinum produce AB exotoxins that affect ___ ___.

A

Nervous tissue

89
Q

Botulinum toxin

A

Consists of several related AB toxins that are the most potent biological toxins known

90
Q

Tetanus toxin

A

Also an AB protein neurotoxin

91
Q

Enterotoxins

A

Exotoxins whose activity affects the small intestine

  • generally cause massive secretion of fluid into the intestinal lumen, resulting in vomiting and diarrhea
92
Q

Example of enterotoxin

A

Cholera toxin

93
Q

Endotoxin

A

The lipopolysaccharide portion of the cell envelope of certain gram-negative bacteria, which is a toxin when solubilized

94
Q

Endotoxins generally ___ toxic than exotoxins.

A

Less

95
Q

Presence of endotoxin can be detected by the …

A

Limulus amoebocyte lysate (LAL) assay

96
Q

Hosts have innate resistance to most pathogens:

A
  • natural host resistance
  • tissue specificity
  • physical and chemical barriers

Microbiology (26 decks)

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