Pathogenic Gram-Positive Bacteria Flashcards
(131 cards)
1
Q
What is the shape of Staphylococcus?
A
Spherical
2
Q
What is the arrangement of Staphylococcus?
A
Clustered
3
Q
Is staphylococci species salt sensitive or salt tolerant?
A
Salt tolerant
4
Q
Staphylococci have the ability to tolerate the salt deposited on human skin by ______
A
Sweat glands
5
Q
What are the 2 species of Staphylococcus that are most associated with staphylococcal diseases in humans?
A
- S. aureus
- S. epidermidis
6
Q
Which species of Staphylococcus is more virulent?
A
S. aureus
7
Q
Which species of Staphylococcus can be an opportunistic pathogen?
A
S. epidermidis
8
Q
What are opsonins?
A
Antibodies that enhance phagocytosis
9
Q
How does protein A interfere with normal antibody binding?
A
Binds to the stems of IgG antibodies
10
Q
Protein A binding ______ opsonization
A
Inhibits
11
Q
What effect does the enzyme coagulase of S. aureus have upon the soluble blood protein fibrinogen?
A
Converts it into insoluble fibrin
12
Q
Insoluble fibrin forms ______
A
Blood clots
13
Q
Only ______ synthesizes coagulase
A
S. aureus
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
15
Q
Staphylococcal food poisoning is considered to be ______
A
Intoxication
16
Q
How are commonly affected foods associated with staphylococcal food poisoning most often contaminated?
A
Bacteria from human skin
17
Q
What effect does warming or reheating of contaminated foods have upon the enterotoxin that causes staphylococcal food poisoning?
A
Inactivates enterotoxins
18
Q
What are the manifestations of staphylococcal food poisoning? (4)
A
- Abdominal pain
- Nausea
- Vomiting
- Diarrhea
19
Q
When do the symptoms of staphylococcal food poisoning typically appear?
A
4 hours
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
21
Q
What specific effect do staphylococcal exfoliative toxins have upon the epidermis?
A
Dissolution of epidermal desmosomes
22
Q
______ create an intercellular bridge proteins that hold cells together
A
Desmosomes
23
Q
Which is the more serious: staphylococcal scalded skin syndrome or secondary bacterial infections?
A
Staphylococcal scalded skin syndrome
24
Q
Describe impetigo
A
Small, flattened, red patches on the face and limbs
25
In what type of people is impetigo most common in?
Children with not fully developed immune systems
26
What are the manifestations of staphylococcal toxic shock syndrome? (5)
- Rash
- Fever
- Vomiting
- Hypotension
- Loss of sheets of skin
27
Describe the nature of the staphylococcal toxic shock syndrome toxin (TSST)
Potentially fatal systemic infection
28
What are the functions of superantigens? (2)
- Release of cytokines
- Hyper inflammatory response
29
When does staphylococcal toxic shock syndrome become fatal?
When hypotension deprives the brain, heart, or vital organs of oxygen
30
Why is staphylococcal toxic shock syndrome associated with super-absorbent Rely brand tampons?
They promote the growth of S. aureus
31
What is the aerotolerance of Streptococcus?
Anaerobic
32
What is the shape of Streptococcus?
Chains
33
Antibody-based classification is known as ______ classification
Serological
34
In Lancefield classification, streptococci is divided into groups based on ...
Group A carbohydrate antigens
35
What is hemolysis?
Lysis of RBCs
36
What is a-hemolysis?
Partial lysis
37
What is b-hemolysis?
Complete lysis
38
What is the causative agent of group A Streptococcus?
S. pyogenes
39
What type of hemolysis is characteristic of Streptococcus pyogenes?
b-hemolysis
40
What are the manifestations of group A streptococcal pyrogenic toxins? (3)
- Fever
- Rash
- Shock
41
What are the 2 main structural features that enable cells of S. pyogenes to evade phagocytosis?
- M protein
- Hyaluronic acid capsule
42
M protein is a membrane localized protein that interferes with ______
Opsonization
43
What is the function of the hyaluronic acid capsule?
Camouflages bacteria from WBCs
44
Where are the genes for Group A streptococcal pyrogenic toxins found?
Temperate bacteriophages
45
What is pharyngitis?
A sore throat
46
What is the causative agent of strep throat?
Streptococci
47
Why does scarlet fever develop in only some cases of streptococcal pharyngitis?
Occurs in infections involving a lysogenized strain of S. pyogenes
48
What role do streptococcal pyrogenic toxins play in scarlet fever?
They trigger a diffuse rash
49
Staphylococcal toxic shock syndrome toxins and streptococcal pyrogenic toxins are both ______
Superantigens
50
What is the causative agent of rheumatic fever?
S. pyogenes
51
What type of response is rheumatic fever?
Autoimmune response
52
What is the causative agent of necrotizing fasciitis?
S. pyogenes
53
What group of a-hemolytic streptococci are not part of any Lancefield group?
Viridans streptococci
54
Explain why viridans streptococci were given their name
They produce green pigment when grown on blood media
55
What is dextran?
An insoluble polysaccharide from glucose
56
What is the function of dextran in the formation of dental carries?
Causes bacteria to stick to dental surfaces
57
Why is dental plaque considered to be a biofilm?
Dextran allows viridans streptococci to colonize the enamel of teeth
58
How do viridans streptococci / Streptococcus mutans dissolve tooth enamel?
They produce acids from fermentation
59
Which early microbiologist discovered Streptococcus pneumoniae in pneumonia patients in 1881?
Louis Pasteur
60
Roughly how many different strains of S. pneumonia make up the so-called pneumococci?
90
61
What type of hemolysis is a characteristic of S. pneumoniae under aerobic vs. anaerobic growth conditions?
a-hemolytic
62
Which parts of the body do pharyngeal microbiota such as S. pneumoniae colonize? (3)
- Lungs
- Sinus
- Middle ear
63
How does the polysaccharide capsule of S. pneumonia with phosphorylcholine enable pneumococci to ‘hide’ inside body cells?
Stimulates host cells to engulf bacteria
64
______ mediates the binding of epithelial cells of the pharynx
Protein adhesin
65
______ destroys IgA antibodies
Secretory IgA protease
66
______ lyses ciliated epithelial cells
Pneumolysin
67
What is the most prevalent disease caused by S. pneumoniae?
Pneumococcal pneumonia
68
What effect do multiplying S. pneumoniae cells in the alveoli have upon the lungs?
Allows fluid, RBCs, and leukocytes to enter the lungs
69
What is pneumococcal meningitis?
Pneumococci spreads to the meninges during sinusitis / otitis media
70
How does the mortality rate of pneumococcal meningitis compare to meningitis caused by other microorganisms?
20 times higher
71
What is the aerotolerance of Bacillus anthracis?
Anaerobic
72
What is the shape of Bacillus anthracis?
Rod-shaped chains
73
Where does B. anthracis normally dwell?
Soil
74
Explain how B. anthracis can survive in dry and lifeless soil for years
It has a tough external coat and internal chemicals
75
What differentiates pathogenic strains of B. anthracis from nonpathogenic ones?
They contain anthrax toxin
76
How is anthrax toxin lethal to host cells?
Causes apoptosis
77
What is apoptosis?
Programmed cell death
78
Which type of anthrax is rare in humans but common in animals, resulting in intestinal hemorrhaging and death?
Gastrointestinal anthrax
79
Which type of anthrax causes nodules and eschar, resulting in the release of toxins into the blood?
Cutaneous anthrax
80
Which type of anthrax causes endospores to germinate in the lungs and secrete toxins?
Inhalation anthrax
81
Clostridium species are obligate ______
Anaerobes
82
What is the causative agent of gas gangrene?
C. perfringens
83
How is gas gangrene contracted?
Endospores are introduced deep in tissues
84
What causes the ‘gas’ in gas gangrene?
Histologic toxins
85
What is the main preventative measure regarding gas gangrene caused by C. perfringens?
Proper cleaning of wounds
86
What is the aerotolerance of Clostridium difficile?
Anaerobic
87
How does Clostridium difficile appear clinically as an opportunistic pathogen?
Appears in patients treated with broad-spectrum antimicrobial drugs
88
What causes hemorrhagic necrosis?
C. difficile endospores
89
What is pseudomembranous colitis?
Large sections of the colon wall slough off resulting in infection
90
What are nosocomial infections?
Hospital acquired infections
91
What is the causative agent of botulism?
C. botulinum
92
Describe the relationship between C. botulinum endospores and neurotoxin production
They germinate in an anaerobic environment to release neurotoxins
93
Describe the effect that botulism toxin has upon muscle contraction
It blocks acetylcholine from motor neurons to muscle cells
94
What is flaccid paralysis?
Inhibition of muscle contraction
95
Botulism is considered ______
Intoxication
96
When fatal, how does death result in victims of botulism?
Victims asphyxiate because they cannot inhale
97
What causes infant botulism?
Pathogen growth in the GI tract
98
What is the causative agent of tetanus?
C. tetani
99
Clostridium is an obligate ______
Anaerobe
100
What is the name of the neurotoxin produced by C. tetani?
Tetanospasmin
101
Describe the effect of tetanospasmin on muscle relaxation
Blocks neurotransmitters - signals contraction
102
What is spastic paralysis?
Uncontrolled muscle contraction
103
When fatal, how does death result in victims of tetanus?
Patients cannot exhale
104
______ is the initial and diagnostic sign of tetanus
Lockjaw
105
What is passive immunization?
Injection of premade antigens directed against the toxin
106
What is tetanus toxoid?
Inactivated toxin
107
Tetanus toxoid is ______ immunization
Active
108
What is the causative agent of diphtheria?
C. diphtheriae
109
How is C. diphtheriae transmitted?
Respiratory droplets
110
What specific effect does diphtheria toxin have on hosts?
It inhibits translation, causing localized cell death
111
Describe the nature of pseudomembrane formation in cases of diphtheria
Dead tissue and fibrous material on the tonsils
112
What is mycolic acid?
Waxy lipid
113
What does the slow growth rate of mycobacteria provide resistance to? (3)
- Gram staining
- Antimicrobial drugs
- Desiccation
114
What type of staining technique is used to differentiate mycobacteria?
Acid-fast staining
115
Name the 2 most common species of Mycobacterium and the diseases they cause
- M. tuberculosis
- M. leprae
116
What are the 3 types of tuberculosis?
- Primary TB
- Secondary (reactivated) TB
- Disseminated TB
117
What role do macrophages play in primary TB?
Phagocytize pathogens
118
What role do collagen fibers play in primary TB?
Enclose infected macrophages within the tubercle
119
What is caseous necrosis?
Release of M. tuberculosis from the center of the tubercle
120
Describe the manifestations and pathology for primary tuberculosis
Small, hard, nodules in the lungs
121
Describe the manifestations and pathology of secondary TB
The tubercle ruptures - active infection
122
Describe the manifestations and pathology of disseminated TB
Macrophages carry pathogens via blood and lymph
123
What is consumption?
Wasting away of the body caused by disseminated TB
124
What is the causative agent of leprosy?
M. leprae
125
What is the alternative name for leprosy?
Hansen’s disease
126
What is the optimum growth temperature for Mycobacterium leprae and how does this relate to the pathology associated with leprosy?
30°C - preference for cooler regions such as peripheral nerve endings, fingers, toes, lips, and earlobes
127
What do the manifestations of leprosy depend upon?
The immune response of the patient
128
Which type of leprosy is a nonprogressive form caused by a strong cell-mediated immune response?
Tuberculoid leprosy
129
Which type of leprosy is caused by a weak cell-mediated immune response?
Lepromatous leprosy
130
How is leprosy transmitted?
Person-to-person contact
131
How are antimicrobials used to control mycobacterial infections?
Multiple drugs are used for 12 months or longer
