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40 Cards in this Set

  • Front
  • Back
what is the cause of most infections? ex?
viruses (40-60%)
adeno, rhino, coxsackie, parainfluenza, coronavirus, HSV
what is the most common bacterial throat infection caused by? what are some other ex?
strep throat (serious cause of pharyngitis) is usually caused by Group A beta hemolytic streptococcus (GAS, GABHS) aka. strep pyogenes
corynebacterium diphtheria, haemophilus influenza, moraxella catarrhalis
signs and symptoms of pharyngitis
pain swallowing
swollen lymph nodes (anterior cervical)
runny nose, postnasal drip
trouble breathing (serious)
what are the complications and sequelae surrounding step throat?
complication (during infection): scarlet fever, bacteremia and strep TSS
sequelae (after infection): rheumatic fever, glomerulonephritis
what is the route of entry for strep pyogenes?
respiratory (respiratory droplet spread)
pathogenesis of strep pyogenes
scarlet fever
rheumatic fever
general charac of strep pyogenes
G+ cocci
facultative anaerobe
upper respiratory tract
catalase neg
toxigenic (streptolysin O)
non spore forming
what type of hemolysis on blood agar plate?
beta hemolysis (via streptolysin)
epidemiology of strep pyogenes
15-20% asx carriers (URT colonization)
respiratory droplet spread; crowded conditions
some ppl at risk for scarlet/rheumatic fever
virulence factors for strep pyogenes
M protein (50 Lancefield serotypes)
lipoteichoic acid
Grp A (carbohydrate)
capsule (hyaluronic acid)
enzyme (hyaluronidase)
pyrogenic (erythrogenic) exotoxins
how does the capsule prevent phagocytosis? how do we override this evasion mxn?
made of hyaluronic acid; mimics BM
give type-specific Ig to M protein
S/S of GABHS pharyngitis
tonsillar exudate
tender anterior cervical lymphadenopathy
clinical disease in pharyngitis
abrupt onset: sore throat, fever, malaise, headache
posterior pharynx: erythematous
cervical lymphadenopathy
(50% w/ pharyngeal, tonsillar exudates)
what might streptococcal pharyngitis be confused with? why?
viral pharyngitis
both have exudate
what is required for diagnosis?
rapid strep, culture, serology
scarlet fever will result during infection with what type of strep species?
lysongenized strep species w/ pyrogenic (erythrogenic)exotoxin (super Ag)
when do sx of of scarlet fever occur and how long do they last?
occur 1-2 days after onset pharyngitis
last 5-7 days
what are the sx of scarlet fever?
erythematous rash on upper chest
->extremities; blanch with pressure; pastia's lines (skin folds); sandpaper feel
strawberry tongue
high fever
nausea, vomiting
when does rheumatic fever occur?
2-3 weeks after pharyngitis
AUTOIMMUNE sequelae w/ untreated, asx pharyngitis
what are the S/S for rheumatic fever?
endocarditis (heart valves)
how is rheumatic fever diagnosed?
Jones criteria
how do you prevent rheumatic fever?
tx patient within 10 days of onset of pharyngitis
what triggers rheumatic fever lesions?
cross-reactivity b/w strep Ag and Ag on myocardium etc
what is the Jones criteria?
diagnosing rheumatic fever
1 required, 2 major, 0 minor OR
1 required, 1 major, 2 minor
what are required, major and minor criteria for rheumatic fever?
required: lab diagnosis (strep Ig, culture, ASO etc)
major: carditis, sydenham's chorea (involuntary movements), polyarthitis, subQ nodules, erythema marginatum (pale center ans round margins)
minor: fever, previous RF, acute phase reactions, prolonged PR interval
what is erythema marginatum? and what might it indicate?
erythematous lesion
pale center
rounded margin
rheumatic fever
where are subcutaneous nodules usually found? what are they assoc with?
extensor surfaces (knee, wrist, elbow)
rarely seen; assoc with sever carditis
how is glomerulonephritis assoc with GABHS?
sequelae (post infection)for pharyngitis or impetigo (superficial skin infection from s. pyogenes)
charac of glomerulonephritis
IC deposited between epithelium and BM
autoimmune (crossreactive w/ s. pyogenes or rel of contained Ag)
parietal and mesangial cells grow and proliferate (restrict lumen of capillaries; affect GFR and RBF)
can lead to irreversible damage in adults
NOT prevented by tx of pharyngitis or impetigo
s/s of glomerulonephritis
lab diagnosis of s. pyogenes pharyngitis
leukocytes WITH s. pyogenes
rapid test
catalas neg
bacitracin sensitive
PYR test positive
are the rapid strep tests specific or sensitive? what does this require?
high specificity (98), low sensitivity(90)
more FN (10%) so if have negative result must be confirmed; if positive, can give antibiotics
what is the PYR test?
smear bacteria on filter paper containing PYR (chemical)
bacteria prod enzyme the hydrolizes PYR to give color
describe the bacitracin test for s. pyogenes
diagnostic test-separates different types of strep
bacitracin on paper disk put on lawned agar; if bacteria are sensitive to it, they will be killed and a plaque will form; diameter is determined by MIC
what are the methods for the rapid strep test?
extraction (enzyme, acid) and identification (immunoassay, latex agglutination)
which type of extraction is more sensitive? which is faster?
enzyme-more sensitive
when are throat cultures required?
not for primary test
used to CONFIRM when had negative rapid
NOT recommended for adults with pharyngitis
which method of identification is used more frequently?
enzyme immunoassay (one step);
latex agglutination can detect different lancefield groups of strep
when do we do a rapid strep? when do we treat?
test with 2 or more s/s of GABHS; treat with pos test OR when presumed GABHS with 3-4 s/s without test
what is the treatment for GABHS?
penicillin G
cephalosporin (oral)
may req 2nd round
tx immediately to prevent rheumatic fever (not glomerulonephritis)
req for rheumatic fever pts in subsequent procedures