Gram Positive Cocci Part 2 (Exam 1) Flashcards
(113 cards)
1
Q
How will strep appear on gram stain
A
gram positive cocci in chains or pairs
2
Q
What will the catalase result of strep be
A
negative
3
Q
What are the environmental requirements for strep
A
facultative anaerobes, some capnophilic
complex nutritional requirements
carbohydrates are fermented and produce lactic acid
4
Q
How are strep classified
A
serology (lancefield groupings)
hemolytic patterns
biochemical properties
5
Q
What are Lancefield groups
A
Group specific cell wall antigens in strep; polysaccharide or teichoic acid
6
Q
What are the group names of Lancefield groups
A
Groups A-W
7
Q
What Lancefield groups are most important
A
ABCDFG
8
Q
How are cell wall antigens of strep detected
A
immunologic assays
9
Q
What are the medically important strep
A
A
B
D
S pneumonia, viridans strep –have no lancefield group
10
Q
What is Group A strep
A
Strep pyogenes
11
Q
What is Group B strep
A
Strep agalactiae
12
Q
What is Group B strep
A
E. faecalis (enterococcus)
13
Q
What are the different types of hemolysis displayed by strep on blood agar
A
alpha beta and gamma
14
Q
What strep are beta hemolytic
A
strep pyogenes
strep agalactiae
15
Q
What strep are alpha hemolytic
A
strep pneumoniae
16
Q
What strep are gamma hemolytic
A
Enterococcus spp
17
Q
What group does strep pyogenes fall into
A
group A beta hemolytic strep
18
Q
WHat diseases are associated with strep pyogenes
A
strep throat
skin infections: necrotizing fasciitis (flesh eating bacteria)
19
Q
How will strep pyogenes appear on gram stain
A
gram positive
cocci
in short chains
20
Q
What type of capsule is seen on S. pyogenes
A
hyaluronic acid
21
Q
What does the capsule on S. pyogenes prevent
A
phagocytosis
22
Q
What adhesins are seen in in S. pyogenes
A
Lipoteichoic acid
M like proteins
F protien
23
Q
What enzymes contribute to the virulence of strep pyogenes
A
streptolysin S and O
streptokinase
DNAse
C5a peptidase
24
Q
What is the most important virulence factor of strep pyogenes
A
M protein
25
What is the streptococcal pyrogenic exotoxin
superantigen, binds outside normal peptide binding groove and causes a cytokine storm
26
What titer is used for rheumatic fever
ASO titer
27
What is ASO titer
anti-streptolysin O (lyse red blood cells)
28
What are the effects of M protein of strep pyogenes
binds to matrix proteins
antiphagocytic
Degrades complement C3b
29
What two diseases of S pyogenes are caused by antigenic variation
Rheumatoid fever
| Acute glomerulonephritis
30
What strains produce rheumatoid fever
Rheumatigenic strains
31
What strains produce acute glomerulonephritis
M12
32
What type of reaction is rheumatic fever
Type II hypersensitivity
33
What is the mechanism of S. pyogenes in rheumatic fever
hypersensitivity reaction
molecular mimicry
antibodies attack heart tissue
34
What does rheumatic fever look like in children
congestive heart failure
35
What type of reaction is acute glomerulonephritis
Type III hypersensitivity
36
WHat is the mechanism that causes acute glomerulonephritis
immune complexes are formed with anatibodies for strep pyogenes that plug up the kidneys
37
What toxin is responsible for the rash in scarlet fever
pyrogenic exotoxins from S. pyogenes
38
What are the pyrogenic exotoxins
4 immunologically distinct heat-labile toxins ABCF
39
Where are the pyrogenic exotoxins found
coded on lysogenized phage
40
What are the presentations of scarlet fever
after strep throat
rash on chest and upper arms (sandpaper rash)
strawberry tongue
41
What toxin of S. pyogenes displays antigenic conversion
pyrogenic exotoxin is a superantigen on a lysogenic phage
42
What is the function of streptolysin S and O
hemolysins
43
What do hemolysins do
lyse WBC, platelets, RBCs and stimulate release of lysosomal enzymes
44
Is streptolysin S immunogenic
no
45
Is streptolysin O immunogenic
yes
46
What causes the beta hemolysis of S pyogenes on blood agar
streptolysin S
47
WHat type of S pyogenes infection will lack anti-ASO antibodies
skin infections: streptolysin O inhibitied by cholesterol in skin lipids
48
What is the function of streptokinases in S. pyogenes
cleave plasminogen to plasmin
| contributes to spread of bacteria
49
what does plasmin do
cleave fibrin and fibrinogen, dissolves clots
50
What is the function of DNase (A-D) in strep pyogenes infections
depolymerize free DNA in pus
51
What does depolymerizing free DNA in pus cause
reduced viscosity of abscess, helps it spread
52
What is DNase a marker for
marker of cutaneous infection
53
What is the funciton of C5a peptidase in S. pyogenes
degrades complement component C5a, inhibits chemotaxis of phagocytes
54
Where is strep pyogenes normally found
oroparynx of healthy children and young adults
55
What percentage of the population are carriers for strep pyogenes
15-20%
56
How is strep pyogenes transmitted for pharyngitis
respiratory droplets
57
How is strep pyogenes transmitted for soft-tissue infections
skin contact, organisms introduced into tissues through break in the skin
58
What are the diseases that are unique to strep pyogenes
rheumatic fever
scarlet fever
acute post-streptococcal glomerulonephritis
59
How will strep throat present
sore throat, fever, malaise, headache, posterior pharynx erythema with exudate
60
What causes the exudate in strep throat
pus in the back of the throat from neutrophils
61
What causes the pain and inflammation in strep throat
neutrophils
62
What are the clinical symptoms of scarlet fever
erythematous rash on upper chest, spreads to extremities
| Strawberry tongue
63
How will S. pyogenes present as a skin infection
pyoderma
| Impetigo
64
What is pyoderma
any purulent skin infection
65
What is impetigo symptoms
vesicles progess to pustules, rupture, and crust over into honey-crusted lesions
66
Where are viridans streptococci found
normal flora of GI, GU, and URT
67
What are the hemolysis patterns of viridans strep
alpha hemolytic
68
WHat are the clinical diseases associated with Strep mutans
Dental plaque cavities
| Subacute bacterial endocarditis
69
What are the clinical diseases associated with Strep sanguinis
bacteremia and endocarditis
70
What are the clinical diseases associated with strep gallolyticus
bacteremia and endocarditis in people with colon cancer
71
How will strep pneumoniae appear on gram stain
gram positive cocci in pairs
72
How will strep pneumoniae appear on culture
alpha hemolytic, round mucoid colonies on culture
73
What is the most common cause of community acquired pneumonia
strep pneumoniae
74
How is strep pneumoniae transmitted
respiratory droplets
75
Where is strep pneumo normally found
normal flora of URT
76
When does strep pneumo disease occur
organisms spread, often preceded by respiratory viral infection and damage ot ciliated epithelial cells
77
What is the only gram positive diplococci discussed
streptococcus pneumoniae
78
What is the most important virulence factor of strep pneumoniae
capsule
79
What is the function of the capsule in strep pneumoniae
phagocytosis and aids in crossing the BBB
80
What organisms with have an IgA protease
strep pneumoniae
Neisseria meningitidis
haemophilus influenza
81
What is the funciton of IgA protease in S. pneumoniae
cleave IgA antibodies
82
What is the function of pneumolysin in S. pneumoniae
binds cholesterol and creates pores that kill ciliated epithelial cells
binds Fc portion of antibody and activates classic complement pathway
83
What type of vaccine is used for S. pneumoniae
conjugate vaccine
84
What is the conjugate vaccine aimed towards
the capsule attached to protein to cause isotype switching to IgA
85
How will pneumococcal pneumonia present
chills, fever, productive cough with blood-tinged sputum
many PMNs
lobar pneumonia
86
Besides pneumonia, what other clinical diseases are associated with strep pneumonia
```
meningitis
sinusitis
otitis media
bacteremia
endocarditis
```
87
Who is at risk with miningitis from strep pneumonia
children and elderly
88
WHo is at risk with sinusitis and otitis media from strep pneumonia
young children
89
How can microscopy of S. pneumoniae be used for diagnosis
lancet shaped gram positive diplococci
quellung reaction
90
How will strep pneuoniae appear on blood agar
alpha hemolytic
91
What tests can be used to identify strep pneumoiae from viridans strep
bile solubility test
| optochin test
92
S pneumoniae colonies do what in bile solubility test
dissolve
93
S. pneumoniae grown in the presence of optochin is what
sensitive
94
What are the enteric cocci discussed
E. faecalis
| E. faecium
95
What cell wall antigen do enterococci display
group D cell wall antigen
96
How will enterococci appear on gram stains and in culture
gram positive cocci in short chains
white colonies on culture
97
What are the environmental requirements of enterococci
Facultative anaerobes
| grow in high salt levels
98
How are enterococci differentiated from strep
enterococci are bile resistant and will grow
strep are bile sensitive
99
Describe the pathogenesis of enterococci
commensal organisms with no toxin
limited potential for causing disease
100
describe the epidemiology of enterococci
recovered in feces and acquired from contaminated food or water
101
Where is E. faecalis found
large intestine and GU tract
102
What are the secrete factors that play a role in virulence of enterococci
cytolysin
chemoattractant for PMNs
Gelatinase
103
What do cytolysins do
inhibit gram + bacteria, induces local tissue damage
104
What does gelatinase do
hydrolyze gelatin, collagen, hemoglobin
105
What type of antibiotic resistance is exhibited by enterococci
multiple plasmid and chromosome genes
resistant to aminoglycosides, beta lactams, vancomycin
106
What are the clinical diseases associated with enterococci
UTIs
Peritonitis
Endocarditis
107
What are symptoms with a UTI
dysuria and pyuria
108
What are symptoms of peritonitis
abdominal swelling and tenderness after abdominal trauma or surgery
109
What patients are at risk for acquiring enterococci infections
pts with urinary, IV catheters
| Pts on broad spectrum antibiotics
110
What is the catalase reaction results of enterococci
negative
111
How are enterococci cultured
grow well on blood agar, chocolate agar, and bile esculin agar
112
On bile esculin agar, how do enterococci appear
black pigment
113
What are the biocheical tests that can be used to diagnoses enterococci
resistance to optochin
bile resistant
PYR+
