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MICRB 106 - Exam 4 > Pathogenic Gram-Positive Bacteria > Flashcards

Pathogenic Gram-Positive Bacteria Flashcards

1
Q

What is the shape of Staphylococcus?

A

Spherical

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2
Q

What is the arrangement of Staphylococcus?

A

Clustered

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3
Q

Is staphylococci species salt sensitive or salt tolerant?

A

Salt tolerant

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4
Q

Staphylococci have the ability to tolerate the salt deposited on human skin by ______

A

Sweat glands

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5
Q

What are the 2 species of Staphylococcus that are most associated with staphylococcal diseases in humans?

A
  • S. aureus
  • S. epidermidis
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6
Q

Which species of Staphylococcus is more virulent?

A

S. aureus

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7
Q

Which species of Staphylococcus can be an opportunistic pathogen?

A

S. epidermidis

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8
Q

What are opsonins?

A

Antibodies that enhance phagocytosis

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9
Q

How does protein A interfere with normal antibody binding?

A

Binds to the stems of IgG antibodies

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10
Q

Protein A binding ______ opsonization

A

Inhibits

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11
Q

What effect does the enzyme coagulase of S. aureus have upon the soluble blood protein fibrinogen?

A

Converts it into insoluble fibrin

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12
Q

Insoluble fibrin forms ______

A

Blood clots

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13
Q

Only ______ synthesizes coagulase

A

S. aureus

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14
Q

What are the functions of the slime layers produced by S. aureus and S. epidermidis? (3)

A
  • Inhibition of chemotaxis
  • Inhibition of endocytosis
  • Attachment of staphylococcus to artificial surfaces
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15
Q

Staphylococcal food poisoning is considered to be ______

A

Intoxication

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16
Q

How are commonly affected foods associated with staphylococcal food poisoning most often contaminated?

A

Bacteria from human skin

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17
Q

What effect does warming or reheating of contaminated foods have upon the enterotoxin that causes staphylococcal food poisoning?

A

Inactivates enterotoxins

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18
Q

What are the manifestations of staphylococcal food poisoning? (4)

A
  • Abdominal pain
  • Nausea
  • Vomiting
  • Diarrhea
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19
Q

When do the symptoms of staphylococcal food poisoning typically appear?

A

4 hours

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20
Q

What is the relationship between exfoliative toxins and staphylococcal scalded skin syndrome?

A

Release of exfoliative toxins into the bloodstream causes the epidermis to peel off

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21
Q

What specific effect do staphylococcal exfoliative toxins have upon the epidermis?

A

Dissolution of epidermal desmosomes

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22
Q

______ create an intercellular bridge proteins that hold cells together

A

Desmosomes

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23
Q

Which is the more serious: staphylococcal scalded skin syndrome or secondary bacterial infections?

A

Staphylococcal scalded skin syndrome

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24
Q

Describe impetigo

A

Small, flattened, red patches on the face and limbs

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25
Q

In what type of people is impetigo most common in?

A

Children with not fully developed immune systems

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26
Q

What are the manifestations of staphylococcal toxic shock syndrome? (5)

A
  • Rash
  • Fever
  • Vomiting
  • Hypotension
  • Loss of sheets of skin
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27
Q

Describe the nature of the staphylococcal toxic shock syndrome toxin (TSST)

A

Potentially fatal systemic infection

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28
Q

What are the functions of superantigens? (2)

A
  • Release of cytokines
  • Hyper inflammatory response
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29
Q

When does staphylococcal toxic shock syndrome become fatal?

A

When hypotension deprives the brain, heart, or vital organs of oxygen

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30
Q

Why is staphylococcal toxic shock syndrome associated with super-absorbent Rely brand tampons?

A

They promote the growth of S. aureus

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31
Q

What is the aerotolerance of Streptococcus?

A

Anaerobic

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32
Q

What is the shape of Streptococcus?

A

Chains

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33
Q

Antibody-based classification is known as ______ classification

A

Serological

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34
Q

In Lancefield classification, streptococci is divided into groups based on …

A

Group A carbohydrate antigens

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35
Q

What is hemolysis?

A

Lysis of RBCs

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36
Q

What is a-hemolysis?

A

Partial lysis

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37
Q

What is b-hemolysis?

A

Complete lysis

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38
Q

What is the causative agent of group A Streptococcus?

A

S. pyogenes

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39
Q

What type of hemolysis is characteristic of Streptococcus pyogenes?

A

b-hemolysis

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40
Q

What are the manifestations of group A streptococcal pyrogenic toxins? (3)

A
  • Fever
  • Rash
  • Shock
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41
Q

What are the 2 main structural features that enable cells of S. pyogenes to evade phagocytosis?

A
  • M protein
  • Hyaluronic acid capsule
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42
Q

M protein is a membrane localized protein that interferes with ______

A

Opsonization

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43
Q

What is the function of the hyaluronic acid capsule?

A

Camouflages bacteria from WBCs

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44
Q

Where are the genes for Group A streptococcal pyrogenic toxins found?

A

Temperate bacteriophages

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45
Q

What is pharyngitis?

A

A sore throat

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46
Q

What is the causative agent of strep throat?

A

Streptococci

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47
Q

Why does scarlet fever develop in only some cases of streptococcal pharyngitis?

A

Occurs in infections involving a lysogenized strain of S. pyogenes

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48
Q

What role do streptococcal pyrogenic toxins play in scarlet fever?

A

They trigger a diffuse rash

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49
Q

Staphylococcal toxic shock syndrome toxins and streptococcal pyrogenic toxins are both ______

A

Superantigens

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50
Q

What is the causative agent of rheumatic fever?

A

S. pyogenes

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51
Q

What type of response is rheumatic fever?

A

Autoimmune response

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52
Q

What is the causative agent of necrotizing fasciitis?

A

S. pyogenes

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53
Q

What group of a-hemolytic streptococci are not part of any Lancefield group?

A

Viridans streptococci

54
Q

Explain why viridans streptococci were given their name

A

They produce green pigment when grown on blood media

55
Q

What is dextran?

A

An insoluble polysaccharide from glucose

56
Q

What is the function of dextran in the formation of dental carries?

A

Causes bacteria to stick to dental surfaces

57
Q

Why is dental plaque considered to be a biofilm?

A

Dextran allows viridans streptococci to colonize the enamel of teeth

58
Q

How do viridans streptococci / Streptococcus mutans dissolve tooth enamel?

A

They produce acids from fermentation

59
Q

Which early microbiologist discovered Streptococcus pneumoniae in pneumonia patients in 1881?

A

Louis Pasteur

60
Q

Roughly how many different strains of S. pneumonia make up the so-called pneumococci?

61
Q

What type of hemolysis is a characteristic of S. pneumoniae under aerobic vs. anaerobic growth conditions?

A

a-hemolytic

62
Q

Which parts of the body do pharyngeal microbiota such as S. pneumoniae colonize? (3)

A
  • Lungs
  • Sinus
  • Middle ear
63
Q

How does the polysaccharide capsule of S. pneumonia with phosphorylcholine enable pneumococci to ‘hide’ inside body cells?

A

Stimulates host cells to engulf bacteria

64
Q

______ mediates the binding of epithelial cells of the pharynx

A

Protein adhesin

65
Q

______ destroys IgA antibodies

A

Secretory IgA protease

66
Q

______ lyses ciliated epithelial cells

A

Pneumolysin

67
Q

What is the most prevalent disease caused by S. pneumoniae?

A

Pneumococcal pneumonia

68
Q

What effect do multiplying S. pneumoniae cells in the alveoli have upon the lungs?

A

Allows fluid, RBCs, and leukocytes to enter the lungs

69
Q

What is pneumococcal meningitis?

A

Pneumococci spreads to the meninges during sinusitis / otitis media

70
Q

How does the mortality rate of pneumococcal meningitis compare to meningitis caused by other microorganisms?

A

20 times higher

71
Q

What is the aerotolerance of Bacillus anthracis?

72
Q

What is the shape of Bacillus anthracis?

A

Rod-shaped chains

73
Q

Where does B. anthracis normally dwell?

74
Q

Explain how B. anthracis can survive in dry and lifeless soil for years

A

It has a tough external coat and internal chemicals

75
Q

What differentiates pathogenic strains of B. anthracis from nonpathogenic ones?

A

They contain anthrax toxin

76
Q

How is anthrax toxin lethal to host cells?

A

Causes apoptosis

77
Q

What is apoptosis?

A

Programmed cell death

78
Q

Which type of anthrax is rare in humans but common in animals, resulting in intestinal hemorrhaging and death?

A

Gastrointestinal anthrax

79
Q

Which type of anthrax causes nodules and eschar, resulting in the release of toxins into the blood?

A

Cutaneous anthrax

80
Q

Which type of anthrax causes endospores to germinate in the lungs and secrete toxins?

A

Inhalation anthrax

81
Q

Clostridium species are obligate ______

82
Q

What is the causative agent of gas gangrene?

A

C. perfringens

83
Q

How is gas gangrene contracted?

A

Endospores are introduced deep in tissues

84
Q

What causes the ‘gas’ in gas gangrene?

A

Histologic toxins

85
Q

What is the main preventative measure regarding gas gangrene caused by C. perfringens?

A

Proper cleaning of wounds

86
Q

What is the aerotolerance of Clostridium difficile?

87
Q

How does Clostridium difficile appear clinically as an opportunistic pathogen?

A

Appears in patients treated with broad-spectrum antimicrobial drugs

88
Q

What causes hemorrhagic necrosis?

A

C. difficile endospores

89
Q

What is pseudomembranous colitis?

A

Large sections of the colon wall slough off resulting in infection

90
Q

What are nosocomial infections?

A

Hospital acquired infections

91
Q

What is the causative agent of botulism?

A

C. botulinum

92
Q

Describe the relationship between C. botulinum endospores and neurotoxin production

A

They germinate in an anaerobic environment to release neurotoxins

93
Q

Describe the effect that botulism toxin has upon muscle contraction

A

It blocks acetylcholine from motor neurons to muscle cells

94
Q

What is flaccid paralysis?

A

Inhibition of muscle contraction

95
Q

Botulism is considered ______

A

Intoxication

96
Q

When fatal, how does death result in victims of botulism?

A

Victims asphyxiate because they cannot inhale

97
Q

What causes infant botulism?

A

Pathogen growth in the GI tract

98
Q

What is the causative agent of tetanus?

99
Q

Clostridium is an obligate ______

100
Q

What is the name of the neurotoxin produced by C. tetani?

A

Tetanospasmin

101
Q

Describe the effect of tetanospasmin on muscle relaxation

A

Blocks neurotransmitters - signals contraction

102
Q

What is spastic paralysis?

A

Uncontrolled muscle contraction

103
Q

When fatal, how does death result in victims of tetanus?

A

Patients cannot exhale

104
Q

______ is the initial and diagnostic sign of tetanus

105
Q

What is passive immunization?

A

Injection of premade antigens directed against the toxin

106
Q

What is tetanus toxoid?

A

Inactivated toxin

107
Q

Tetanus toxoid is ______ immunization

108
Q

What is the causative agent of diphtheria?

A

C. diphtheriae

109
Q

How is C. diphtheriae transmitted?

A

Respiratory droplets

110
Q

What specific effect does diphtheria toxin have on hosts?

A

It inhibits translation, causing localized cell death

111
Q

Describe the nature of pseudomembrane formation in cases of diphtheria

A

Dead tissue and fibrous material on the tonsils

112
Q

What is mycolic acid?

A

Waxy lipid

113
Q

What does the slow growth rate of mycobacteria provide resistance to? (3)

A
  • Gram staining
  • Antimicrobial drugs
  • Desiccation
114
Q

What type of staining technique is used to differentiate mycobacteria?

A

Acid-fast staining

115
Q

Name the 2 most common species of Mycobacterium and the diseases they cause

A
  • M. tuberculosis
  • M. leprae
116
Q

What are the 3 types of tuberculosis?

A
  • Primary TB
  • Secondary (reactivated) TB
  • Disseminated TB
117
Q

What role do macrophages play in primary TB?

A

Phagocytize pathogens

118
Q

What role do collagen fibers play in primary TB?

A

Enclose infected macrophages within the tubercle

119
Q

What is caseous necrosis?

A

Release of M. tuberculosis from the center of the tubercle

120
Q

Describe the manifestations and pathology for primary tuberculosis

A

Small, hard, nodules in the lungs

121
Q

Describe the manifestations and pathology of secondary TB

A

The tubercle ruptures - active infection

122
Q

Describe the manifestations and pathology of disseminated TB

A

Macrophages carry pathogens via blood and lymph

123
Q

What is consumption?

A

Wasting away of the body caused by disseminated TB

124
Q

What is the causative agent of leprosy?

125
Q

What is the alternative name for leprosy?

A

Hansen’s disease

126
Q

What is the optimum growth temperature for Mycobacterium leprae and how does this relate to the pathology associated with leprosy?

A

30°C - preference for cooler regions such as peripheral nerve endings, fingers, toes, lips, and earlobes

127
Q

What do the manifestations of leprosy depend upon?

A

The immune response of the patient

128
Q

Which type of leprosy is a nonprogressive form caused by a strong cell-mediated immune response?

A

Tuberculoid leprosy

129
Q

Which type of leprosy is caused by a weak cell-mediated immune response?

A

Lepromatous leprosy

130
Q

How is leprosy transmitted?

A

Person-to-person contact

131
Q

How are antimicrobials used to control mycobacterial infections?

A

Multiple drugs are used for 12 months or longer

MICRB 106 - Exam 4 (4 decks)

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