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Gram-positive cocci Flashcards

(106 cards)

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1
Q

What lab findings are useful to help diagnose Strep. pneumoniae?

A

spinal tap cloudy w/ increase in PMNs and low glucose

lancet-shaped gram+ cocci

alpha-hemolytic on blood agar

inhibited by optochin

older cells may appear gram-

lysed by bile

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2
Q

Identify the major virulence/toxicity factor associated with Staph. saprophyticus.

A

novobiocin resistant

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3
Q

How is Strep. agalactiae (group B strep) transmitted?

A

during childbirth from mother to infant

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4
Q

Identify the major virulence/toxicity factor associated with Strep. viridans.

A

destran biofilm-mediated adhesion to teeth and heart valves

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5
Q

What is the morphology of Group D Strep./Enterococcus?

A

cocci

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6
Q

Name some pyogenic manifestations of Strep. pyogenes.

A

pharyngitis, cellulitis, impetigo

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7
Q

When do you test for bacitracin sensitivity or resisitance?

A

to distinguish beta-hemolytic strep.

bacitracin-sensitive suggests GABHS (strep. pyogenes)

bacitracin-resistant suggests GBBHS (strep. agalactiae)

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8
Q

What organisms are beta hemolytic?

A

Staph. aureus, Strep. pyogenes, Strep. agalactiae, Lysteria monocytogenes

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9
Q

Identify the major virulence/toxicity factors associated with Strep. pyogenes (GABHS).

A

erythrogenic toxin may lead to scarlet fever which can progress to rheumatic fever

hyaluronic acid capsule in non-immunogenic, inhibiting phagoctyic uptake

M-protein is antiphagocytic

M12 strains associated with acute glomerulonephritis

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10
Q

Staph. aureus is catalase __ and coagulase __.

A

+

+

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11
Q

Viridans strep are catalase __ and optochin __.

A

sensitive

resistant

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12
Q

How does Strep. agalactiae gram stain?

A

+

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13
Q

T/F: enterococci (group D strep.) are penicillin G sensitive and show variable hemolysis

A

F - they are resistant but do have variable hemolysis

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14
Q

What is the “most common” associated with Strep. agalactiae?

A

neonatal sepsis and meningitis

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15
Q

What are catalase and coagulase tests used for?

A

Catalase is used to distinguish staph (+) from strep (-)

Coagulase is used to distinguish S. aureus (+) from S. epidermis and S. saprophyticus (-)

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16
Q

How does Strep. pneumoniae gram stain?

A

+

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17
Q

What is the morphology of Strep. pneumoniae?

A

cocci

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18
Q

What lab findings are useful to help diagnose Staph. saprophyticus?

A

+ growth on blood agar

+ catalase

+ gamma hemolysis

+ novobiocin resistance

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19
Q

Strep. pyogenes is catalase __ and bacitracin __.

A

negative

sensitive

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20
Q

What is the second leading cause of UTIs in sexually active women?

A

Staph. saprophyticus

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21
Q

What are the clinical manifestations of Strep. pneumoniae?

A

pneumonia, meningitis, bacteremia, OM, sinusitis

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22
Q

What lab findings are useful to help diagnose Staph. epidermidis?

A

gram + cocci arranged in clusters

catalase +

coagulase -

no hemolysis

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23
Q

What is the “most common” associated with Strep. pneumoniae?

A

bacterial pneumonia in adults

meningitis

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24
Q

What lab findings are useful to help diagnose Strep. pyogenes?

A

beta hemolysis +

susceptible to bacitracin

rapid antigen strep test

gram + cocci in chains

catalase -

ASO titer for rheumatic fever

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25
Does Staph. aureus gram stain positive or negative?
+
26
Staph. aureus: TSST is a superantigen that binds to __ and __ receptors. This causes __ of T cells, leading to toxic shock syndrome.
MHC II T-cell receptors polyclonal activation of T-cells
27
What is the major reservoir for Strep. agalactiae?
normal flora of female genital tract GI tract
28
What is the morphology of Strep. pyogenes?
cocci in chains or pairs
29
Name some key lab findings that are useful to help diagnose Staph. aureus.
gram+ yellow, grape-like clusters on blood agar beta-hemolytic catalase + coagulase + salt tolerant ferments mannitol (s. epidermidis cannot) Facultative anaerobe
30
Identify the major virulence/toxicity factors associated with Strep. agalactiae.
penicillin resistant encapsulated beta-hemolysin CAMP factor
31
List the SSx of rheumatic fever.
polyarthritis, erythema marginatum, chorea, carditis, subQ nodules
32
Identify the major virulence/toxicity factor associated with Strep. pneumoniae.
can make over 85 antigenically distinct capsular polysaccharides, which can interfere with phagocytosis.
33
Identify four major virulence/toxicity factors associated with Staph. aureus.
protein A inhibits phagocytosis, binds Fc portion of antibody - Bind Fc region on IgG → ↓ Complement activation → ↓ C3b enterotoxins A-E are heat stable TSST-1 causes TSS coagulases convert fibrinogen to a fibrin clot exfoliatins cause scalded skin syndrome
34
What is the morphology of Staph. epidermidis?
cocci
35
Strep. pneumococci are catalase __ and optochin __.
- sensitive
36
What are the "most commons" associated with Strep. pyogenes?
pharyngitis cellulitis erysipelas in children
37
What are the clinical manifestations of Strep. agalactiae?
acute lower UTI (uncommon) neonatal pneumonia sepsis meningitis
38
What is the morphology of Staph. saprophyticus?
cocci
39
What are the clinical manifestations of Staph. saprophyticus?
UTIs, esp. in young sexually active women Sx: dysuria, hematuria, frequent urination, burning urination and urgency
40
What lab findings are useful to help diagnose Strep. viridans?
alpha-hemolytic resistant to optochin gram+ cocci in chains bile resistant
41
Staph. aureus: What is the function of protein A?
virulence factor - binds to Fc-IgG and inhibits complement fixation and phagocytosis
42
How is Strep. pneumoniae transmitted?
respiratory drops
43
Does Staph. aureus ferment lactose?
no
44
T/F: S. aurues causes skin disease and organ abscesses, but not pneumonia
F - causes all 3
45
How does Staph. saprophyticus gram stain?
+
46
What are the pyogenic, immunologic and toxigenic clinical manifestations of Strep. pyogenes?
pyogenic (pharyngitis, impetigo, cellulitis, erysipelas) immunogenic (glomerulonephritis, erythema nodosum, rheumatic fever, rheumatic heart disease) toxigenic (scarlet fever, purperal fever)
47
Identify the major virulence/toxicity factors associated with Staph. epidermidis.
highly antibiotic resistant (PSM peptide toxin) can form biofilm and adhere to surfaces like catheters
48
What is the major reservoir for Strep. pneumoniae?
human upper respiratory tract
49
How does Strep. viridans gram stain?
+
50
What are the clinical manifestations of Staph. epidermidis?
prosthetic, surgical and wound infections (nosocomial) especially in the immunocompromised patient inflammation at site of infection, fever, fatigue
51
How does Staph. epidermidis gram stain?
+
52
Viridans strep are __ hemolytic
alpha
53
Identify relevant epidemiology and risk factors associated with Staph. aureus.
surgery or any break in the skin severe neutropenia IV drug abuse chronic granulomatous disease
54
How is Staph. aureus transmitted?
hands and sneezing surgical wounds contaminated foods, esp. home canned meats, potato salad
55
Name three toxins of S. aureus and a syndrome caused by each.
TSST-1 (TSS) exofoliative toxin (scalded skin syndrome) enterotoxins (rapid onset food poisoning)
56
How does group D Strep/enterococcus gram stain?
+
57
What lab findings are useful to help diagnose Strep. agalactiae?
catalase - beta-hemolytic on blood agar bacitraicin resistant CAMP+ (indicates group B) hydrolyzes hippurate
58
What organisms are alpha-hemolytic?
strep. pneumoniae | strep. viridans
59
T/F: S. aureus causes acute bacterial endocarditis.
T
60
Strep agalactiae is catalase __ and bacitracin __.
- resistant
61
What are the clinical manifestations of group D strep/enterococcus?
URI (rare, but severe in immunocompromised, esp. following GI surgery) sepsis dt contaminated needle use (rare).
62
How does Staph. aureus cause toxic shock syndrome?
The toxin is a superantigen that binds to MHC II protein and T-cell receptors and induces IL-1 and IL-2, causing TSS
63
T/F: S. aureus food poisoning is due to bacterial infiltration of the intestinal wall.
F, dt ingestion of preformed enterotoxin
64
What are the clinical manifestations of Strep. viridans?
opportunistic infections of heart valves, blood, skin or wounds Strep. mutans causes dental caries.
65
Identify relevant epidemiology and risk factors associated with Strep. pneumoniae.
individuals with depressed cough reflex or damaged mucociliary elevator pulmonary circulation problems splenectomy head trauma alcoholism sickle cell anemia
66
What is the morphology of Strep. viridans?
cocci
67
How is Strep. pyogenes transmitted?
respiratory droplets direct contact with skin direct contact with objects.
68
How is Strep. viridans transmitted?
usually already present in host dental work may expose organism to heart valves which, if damaged, may become infected
69
What lab findings are useful to help diagnose group D strep/enterococcus?
mostly alpha- or non-hemolytic resistant to bile salts
70
Name the bacteria that produces a yellow pigment.
S. aureus
71
What is the morphology of Staph. aureus?
cocci
72
Which are not toxigenic manifestations of Strep. pyogenes: scarlet fever, rheumatic fever, TSS, acute glomerulonephritis.
rheumatic fever and acute glomerulonephritis are immune-mediated manifestations
73
How do you differentiate Strep. viridans from Strep. pneumoniae in the lab?
both are alpha-hemolytic, but viridans strep is resistant to optochin
74
What is the major reservoir for Strep. pyogenes?
human throat and skin
75
Name nine clinical manifestations of Staph. aureus.
impetigo gastroenteritis infective endocarditis abscesses and mastitis TSS pneumonia surgical infections osteomyelitis necrotizing fasciitis
76
One hour after eating custard at a picnic, the whole family vomits. After 10 hours all are better. Organism?
S. aureus (produces preformed enterotoxin)
77
Does Strep. pyogenes gram stain positive or negative?
+
78
What is the morphology of Strep. agalactiae?
cocci
79
Which of the following agar media is most selective for Staphylococcus aureus?
Mannitol salt agar is a selective medium for Staphylococcus aureus. Mannitol is a carbohydrate that is fermented by S. aureus, leading to acid production and a change in the color of the agar.
80
examples of beta-hemolytic gram + cocci microbes.
Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus agalactiae
81
Which 2 staphs are novobiocin sensitive?
s. Epidermidis s. Aureus
82
Food most assoc. w/ s. aureus gastroenteritis?
Dairy
83
S. aureus exfoliative toxin cleaves _____
desmoglein 1, leading to scalded skin syndrome Nikolsky sign on infants
84
necrotizing fasciitis is caused by ____ , an endo/exo toxin secreted by s. aureus
Panton-Valentine leukocidin is an exotoxin secreted by S. aureus.
85
In the setting of infectious parotitis, serum amylase will be ___while serum lipase will be ___
elevated normal
86
bacterial endocarditis affects which valve first? Two other signs Risk factor?
Tricuspid valve - tricuspid regurg Splinter hemorrhages, Osler nodes IV drug use
87
S. aureus osteomyelitis most commonly affects which bone in adults? Children?
Adults - vertebrae Children - long bones/femur In diabetics- fist metatarsal
88
what does the mec gene encode for? How does s. aureus acquire it?
PBP-2A is encoded by the mec gene and provides resistance to β-lactam antibiotics. (Penicillin binding protein) Acquired via transduction, a form of horizontal gene transfer in which viral bacteriophages transfer bacterial DNA from one bacteria to another.
89
S. epidermidis infections are most commonly associated with
Central lines/ foreign body infections
90
Urinalysis in S. saprophyticus UTI will show
+ WBCs, positive leukocyte esterase, and negative nitrites.
91
OVRPS a
Optochin sensitivity Viridans - resistant s. Pneumonia - sensitive Alpha hemolytic
92
B-BRAS
Basitracin sensitivity Group B (agalactiae) - resistant Group A (pyogenes) - sensitive
93
S. pneumoniae have the ability to cleave which immunoglobulin?
IgA, allows it to invade the mucosa
94
S. sanguinis is the most associated with
bacterial endocarditis after dental procedures.
95
Toxin assoc. w/ s. pyogenes and function
Streptolysin O, highly antigenic exotoxin that degrades cell membranes
96
JONES -> what disease? causative agent?
S. Pyogenes RHeumatic fever Joints - polyarthritis O (<3) - carditis Nodules - sub cu Erythema rash Sydenham Chorea Also, ↑ ESR, fever
97
Common findings of scarlet fever
sandpaper-like maculopapular rash, strawberry tongue,
98
erysipelas vs. cellulits
erysipelas - well demarcated rash on lower limbs (possibly face) cellulitis - not well demarcated, infection is deep in dermis. Streaking erythema towards lymph nodes
99
Which type of hypersensitivity response is acute rheumatic fever?
II
100
Which type of hypersensitivity response is poststreptococcal glomerulonephritis? Explain
III, caused by deposition of antigen-immune complexes in basement membrane of glomerulus.
101
The capsule of s. agalactiae is made of
sialic acid polysaccharide capsule
102
Pregnant women are screened for S. agalactiae colonization at which point in gestation?
36 w
103
Neonatal meningitis is caused by: Sings:
s. agalactiae bulging fontanelle, lethargy, hypotonia, poor appetite, and thermoregulatory dysfunction
104
S. gallolyticus (previously named S. bovis) type of hemolysis causes oxygen preference?
Gamma hemolysis Bovis in blood = cancer in colon facultative anaerobe
105
gallolyticus vs. enterococci
gallolyticus is PYR - enterococci is PYR + both are gamma-hemolytic
106

NPLEX - Micro/Immuno (18 decks)

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