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RC Test 4 > B4.068 - Staph Aureus a Pyogenic Model > Flashcards

B4.068 - Staph Aureus a Pyogenic Model Flashcards

1
Q

common gram negative pus forming bacteria

A

Neisseria E. Coli Pseudomonas

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2
Q

common gram positive pus forming bacteria

A

Strep pyogens staph aureus

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3
Q

what is suppuration

A

the formation of pus

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4
Q

what is pus

A

a mixture of living and dead neutrophils, bacteria and cellular debris

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5
Q

where does pus usually form

A

in an area of persistent infection

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6
Q

what is an abcess

A

a circumscribed collection of pus associated with infection

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7
Q

does an abscess respond to antibodies or antibiotics

A

no, not accessible

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8
Q

one way to get rid of abscesses

A

drain it

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9
Q

how do abscesses form

A

activation of macrophages and other cells of the innate immune system chemotactic factors produced by resident cells - acute phase response activation of adaptive immunity and Th17 acute inflammation

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10
Q

what cells are involved in acute inflammation

A

infiltration of neutrophils production of lysosomal enzymes

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11
Q

describe how the shape of an abscess forms

A

the inflammatory area is contained within a thick walled fibrin capsule the host thinks it has contained an invading organism

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12
Q

what is a complication of abscesses

A

if the abscess happens to be in or near a vital organ or tissue it can often have serious consequences

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13
Q

describe staph a.

A

gram + coccus grows in irregular grape like clusters non motile, non spore forming and catalase and coagulase positive

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14
Q

what is staph a resistant to

A

high temp high salt (haloduric) drying

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15
Q

describe how staph a looks

A

colonies are golden and strongly beta hemolytic on blood agar

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16
Q

describe staph a on mannitol salt agar

A

produces a yellow color with phenol red indicator

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17
Q

what is ClfB

A

clumping factor B

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18
Q

what is IsdA

A

iron regulated surface determinant

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19
Q

what populations have higher rates of staph colonization

A

health care workiers diabetics patients on dialysis

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20
Q

main site of staph a colonization

A

anterior nares

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21
Q

other staph a colonization sites

A

axilla, rectum, perineum vaginal carriage rate is 10% in premenopausal women, rate higher during menses

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22
Q

how can staph spread inside the body

A

from abscesses heatogenously

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23
Q

how does staph. a spread hematogenously

A

due to proteolytic enzymes

can result in pneumonia, bone and joint infection and heart valve infection

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24
Q
A

janeway lesions seen in endocarditis

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25
osler nodes seen in endocarditis
26
roth spots seen in endocarditis
27
how does endocarditis initially present
fever and malaise
28
mortality rate of staph a septicemia
80%
29
mortality rate of staph a TSS
3-5%
30
TSS criteria for diagnosis
Fever \> 38.9 Rash hypotension nausea, vomiting, diarrhea myalgia, high Cr conjuctival hyperemia blood urea high high bilirubin, transaminases thrombocytopenia disorentation
31
what is a concern for a neutropenic cancer patietn with a central venous line
sepsis due to s. aureus
32
most frequent cause of septicemia following a surgical procedure
staph aureas
33
most common place to contract MRSA
hospital
34
common manifestations of staph
skin wound scalded skin syndrome
35
common staph skin infections
folliculitis furuncles, carbuncles impetigo
36
what is ritter disease
scalded skin syndrome
37
folliculitis a tender pustule involving a hair follicle
38
furuncle small abscess that exudes purulent material from a single opening
39
carbuncle an aggregate of furuncles with several openings
40
typical findings of septic arthritis
warmth erythema tenderness of the joint with symptoms and fever **infection almost always unilateral**
41
what is osteomyelitis
bone infection indicated by fever and bony tenderness or limp
42
catheter associated infections are often due to what
staph epidermis
43
urinary tract infections in sexually active young firls often due to
staph saprophyticus
44
staph saprophyticus symptoms
often seen in sexually active young girls dysuria pyuria
45
does staph aureus have a capsule
yes, inhibits phagocytosis
46
what is protein A
seen in staph a binds to the H chain of antibody and can inhibit antibody opsonization preventing phagocytosis. can activate the classical C pathway
47
is s. aureus coagulase + or -
positive this means it was the ability to coagulate plasma and form a fibrin barrier around infectious loci.
48
what is staphylokinase
something staph aureus can relase that breaks down fibrin clots, note it is also coagulase + so it has the ability to make clots and break them down
49
what is PVL
panton valentine leukocidin a phage derived **exotoxin** that causes leukocyte destruction and necrosis. espeicially in the skin and lungs
50
what are exfoliatin toxins
seen in staph aureus consists of ETA or ETB result in scalded skin syndrome
51
features of scalded skin syndrome
fever erythema blisters (bullae) which eventually rupture adn leave a red base. **positive nikoskys signs**
52
what is bullous impetigo
a localized form of SSSS unlike disseminated SSSS the bulae are **culture positive** **nikoskys sign absent** occurs primarily in infants and young children highly communicable
53
what are enterotoxins A-E adn G-I
responsible for types of common food poisoning staph aureus supeantigens that stimulate ceratin T cells by binding to the TCR Vbeta chain stimulate production of cytokines like IFN gamma and TNF causing inflammation of the tissues
54
antigen on left superantigen on right
55
what are enterotoxins and what do they do
often localized to the gut but can be fatal if systemic often occur from skin of food handlers cause vomiting and watery diarrhea 2-6 hours after ingestion symptoms usually self limited
56
should you give antibiotics for enterotoxin mediated staph food poisoning
no it wont help, the toxin is there its not the bug causing the problem. its self limited
57
what is TSS
caused by a superantigen first described in children frequently associated with tampons associated with strains that produced TSST-1 mimics endotoxic shock
58
what strains other than ones that produce TSST-1 can cause toxic shock
ones that produce enterotoxin B, C can cause 50% of cases of non mestrual TSS pathophys mimics endotoxic shock
59
case definition of TSS
fever diffuse macular erythema may mimic sunburn rash hypotension involvement of organ systems GI - emesis or diarrhea renal dysfunction hematologic - low platelets muscular - severe myalgia hepatic - elevated liver enzymes NS - diorientation
60
diagnosis fo staph aureus
culturs with susceptibility testing blood culture may be positive when results from other cultures are negative
61
most purulent infections caused by what
staph aureus unless proven otherwise
62
most important defense agaistn s. aureus
neutrophils
63
what are important immunological factors for defense against staph aureus
opsonization and antibody and C' involved
64
what is not a major factor in staph aureus defense
MAC
65
what adaptive components of the immune system are importatn in staph aureus defense
T cells - Th17 IL-1
66
what is the most important innate immune system componet for staph aureus
TLR-2 - peptidoglycan
67
women who experiecen TSS have what
lower antibody titers againts TSST-1
68
coagulase negative staph types
staph epidermidis most common lack many virulence factors and often require a means of entry
69
staph epidermidis can cause problems with what
artifical heart valves, strep more common for natural valves also catheters
70
what indicates a positive coagulase test
formation of fibrin clot or gel
71
why does staph enterotoxin B cause observed clinical effects
it activates certain T cells to produce cytokines
72
staph superantigens stimulate what
T cells
73
endotoxins stimulate what part of the immune system
macrophages
74
left - spider bite right - MRSA differentiate using a culture

RC Test 4 (10 decks)

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