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Dermatology > Cross Strep Lecture > Flashcards

Cross Strep Lecture Flashcards

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1
Q

micro props of Strep

A

spherical GPCs in pairs, chains.
Cat-
hemolytic props important

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2
Q

GAS is

A

strep pyogenes

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3
Q

GBS is

A

strep agalactiae

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4
Q

Group D strep is

A

ENterococcus faecalis/faecium OR s bovis

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5
Q

GAS causes disease broadly by…

A

pyogenic inflamm
exotoxin
immunologic

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6
Q

b-hemolytic strep classified based on…

A

arranged in Lancefield groups based on Ag differences in C carbohydrate in CW

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7
Q

1st step in dx strep pharyngitis

A

rapid Ag test

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8
Q

strep pharyngitis cause

A

GAS

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9
Q

GAS pharyngitis dx

A

rapid strep Ag test, 10 min. spec, not sens. Throat swab. Ags extracted and reacted with Ab:latex –> agglut if GAS is present.

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10
Q

If rapid Ag test is negative but high suspicion of GAS pharyngitis, next step?

A

throat culture

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11
Q

what does alpha hemolysis look like?

A

green zone around colonies due to incomplete lysis

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12
Q

what does beta hemolysis look like?

A

clear zone around colonies due to complete RBC lysis

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13
Q

gamma hemolysis

A

no lysis

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14
Q

beta-hemolysis due to…

A

Streptolysin O: oxygen labile, UNDER agar surface

Streptolysin S: oxygen stable. ON agar surface

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15
Q

to test pt’s blood for past GAS pharyngitis, what Ab test for?

A

anti-streptolysin O

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16
Q

bact that are alpha hemolytic

A

viridans

s pneumo

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17
Q

bact that are beta hemolytic

A

GAS
GBS
GCS/GGS

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18
Q

bact that are non hemolytic

A

GDS. S bovis, enterococcus. some alpha hemolytic though

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19
Q

GAS virulence factors

A 
M prot
polysacch capsule
hyaluronidase
streptokinase
DNase
C5a peptidase
strep chemok protease
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20
Q

M protein

A

most important anti-phago of GAS. from outer cell surf, interferes w phagocyt. 80 serotypes.

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21
Q

polysaccharide capsule of GAS

A

hyaluronic acid. anti-phago, and no Ab formed against

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22
Q

hyaluronidase

A

GAS. degrades hyaluronic acid in subQ tissue. “spreading factor” helps GAS spread in cullulitis, etc

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23
Q

streptokinase

A

GAS. activates plasminogen –>plasmin. dissolves fibrin in clots, thrombi, emboli

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24
Q

DNase

A

GAS. degrades DNA in exudates/necrotic tissue. protects from NETS

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25
C5a peptidase
cleaves C5a from complement, minimizes influx of neuts in early inf
26
strep chemok protease
prevents mig of neuts into site of inf by degrading IL-8
27
GAS pharyngitis can do WHAT if untx
otitis media, sinusitis, mastoiditis, meningitis, peritonsillar/retropharyngeal abscess immune: rheumatic fever
28
GAS tx
do NOT delay! Oral penicillin, amox, orcephalexin 10 days | allergy? Azithromycin, clarithro, clinda.
29
GAS toxins
erythrogenic toxin pyrogenic exotoxin A exotoxin B
30
erythrogenic toxin
GAS. resp for rash of scarlet fever. SuperAg
31
pyrogenic exotoxin A
GAS. causes most cases of TSS. SuperAg--lots of cytok released
32
exotoxin B
GAS. protease that rapidly destroys tissue, prod in large amoutns by "flesh eating" GAS strains --> nec fasciitis
33
when does strep TSS occur
GAS infection, skin/ vagina/ pharynx. At site of minor trauma pts dev deep inf within 48-72 hrs, esp in soft tissue of an extremity
34
strep TSS can progress to...
75% progress to necrotizing fasciitis
35
sx of strep TSS
diffuse eryth, fever, chills, myalgia, n/v/d, hypothermia, hypoTN, AMS
36
complications of strep TSS
DIC AKI ARDS necrotizing fasciitis
37
dx criteria of strep TSS
isolate GAS from normally sterile site (blood, CSF, biopsy) and hypoTN + other organs
38
tx strep TSS
penicillin + clinda
39
puerperal sepsis, endometritis
GAS abdominal pain, hypoTN, fever 3.5% fatal
40
post-strep GN cause
nephritogenic strains of GAS. happens post-SKIN inf. Ab:Ag complexes on GBM.
41
post-strep GN sx
HTN, facial edema, LE edema, dark urine
42
can post-strep GN be prevented?
probably not. most recover completely
43
acute rheumatic fever cause
2 weeks after GAS pharyngitis, rheumatogenic strain. Ab against GAS prots cross react w host Ags in organs
44
Jones Criteria for acute rheumatic fever dx
``` Joints Carditis Nodules Erythema marginatum Sydenham chorea (neuro dis consisting of abrupt invol motion) ```
45
help to acute rheumatic fever dx
ASO titer
46
tx acute rheumatic fever
full course of antibiotic tx to eradicate any residual GAS. | THEN: prevent strep w prophylaxis in pts with hx of RF (penicillin monthly)
47
brain abscess
viridans | peptostreptococcus
48
peptostreptococcus
anaerobe flora of gut, mouth, female genital tract often in mixed anaerobic inf. tx: penicillin
49
endocarditis of s. bovis associated with....
colon carcinoma
50
Janeway lesions
endocarditis. macular, nonpainful, eryth lesions on palms, soles
51
Osler's nodes
endocarditis. painful violaceous nodules in finger, toe pulm. subacute IE > acute
52
Roth spots
endocarditis. exudative, edematous hemorrhagic lesions of retina
53
endocarditis of s bovis
3 sets of blood cultures necessary to get a + | 100% fatal!!
54
Group D strep defining features
esculin-hydrolyzing if bile present
55
types of GDS
enterococcus (faecalis/faecium) and s bovis
56
entercoccus defining features
esculin-hydrolyzing in bile grow in hypertonic saline grow in bile low virulence, capsule. enzymes. colon flora
57
diseases of enterococcus
hosp-acq UTI, blood stream inf, endocarditis
58
tx enterococcus
combo antibiotic: PCN/vanc, aminoglycoside. check susc
59
vanco resistant entercoccus
more likely faeciUM. tx w linezolid or dapto
60
s bovis props
hydrolyze esculin in presence of bile | not grow in hypertonic saline
61
s bovis disease
endocarditis in pts w colon cancer.
62
s bovis endocarditis tx
PCN, ceftriaxone, vanco
63
VRE mech of resist
gene that encodes enz for D-lactate substit in peptidoglycan
64
GBS micro
narrow zone b-hemolyssi no esculin hydrolysis bacitracin-R (opp to GAS)
65
CAMP test
protein is produced that enhances hemolysis on sheep blood when + to beta-hemolysin of GAS
66
virulence of GBS
inflamm resp. no toxins, enz. polysacch capsule is antiphago
67
clinical GBS
genital tract of some women. Inf acq in utero or passage. babies: neonatal sepsis, meningitis, PNA adults: invasive (septic arthritis, cellulitis, osteomyelitis.)
68
risk factor of GBS
PROM >18 hr in colonized women, babies <37 wks, children whose moms lack Abs. adults: DM, breast cancer
69
GBS dx
grain stain culture rapid test for vaginal/rectal but not great. detectsDNA
70
tx GBS
penicillin/ampicillin | vanc if allergies
71
prevent GBS
screen all pregnant women 35-37 weeks. Admin PenG/Amp IV at time of delivery
72
most common cause of subacute bact endocarditis?
viridans
73
viridans diff lab props
alpha hemolytic bile-lysis resist optochin resistq
74
viridans props
flora of mouth, colon. Enter blood post dental surgery or those w cavities
75
strep mutans
viridans group. causes dental caries. makes polysacch in dental plaque
76
pathogenesis of viridans
no enz, toxins. Can make glycocalyx (att to heart valve). Brain abscess, endocard, liver/abd abscess
77
tx viridans
dep on susc penicillin, ceftriaxone for endocarditis with intermedsusc to PCN, + gentamycin

Dermatology (14 decks)

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