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31 Cards in this Set
- Front
- Back
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Most Upper respiratory Tract Infections are due to __________ causes
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Viral
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What are some of the common misconceptions concerning strep pharygitis?
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Can be diagnosed clinically
Direct Ag testing has replaced culture Effective antimicrobial treatment relieves the symptoms Can discontinue antibiotics when the symptoms go away |
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What is the reason for most antibiotic therapy that is used in strep pharyngitis infections?
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Tx is given in order to decrease the risk/ prevent the onset of Rheumatic Fever
Patient must be compliant with therapy even thought they might be asymptomatic |
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Bacterial Strep Pharyngitis is most common in what demographic?
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In children ages 5-10; incidence highest in late winter and early spring
Most cases of pharyngitis are casued by viral agents especially in adults |
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What are some of the clinical manifestations of strep pharyngitis?
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abrupt onset of sore throat with pain on swallowing
nausea, vomitting (especially in children) Fever above 102.5 Red edematous posterior pharynx Small pinpoint, focal and confluent areas of yellow to gray exudate present on tonsils |
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What is the cause of Scarlet Fever?
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Group A strep lysogenized with bacteriophage that induces the production of erythrogenic toxin
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What are some of the clinical manifestations of scarlet fever?
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Strawberry tongue
Diffuse erythematous blanching ras desquamification of the skin on onset |
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Describe Streptococcus Pyogenes (Group A strep)
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Gram positive cocci in chains
Catalase negative Beta Hemolytic Ferment glucose to lactose sensitive to bacitracin |
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What do the fibrils of strep pyogenes contain and how does it act as a virulence factor?
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M protein and lipoteichoic acid
M proteins antiphagocytic and prevents opsonization by C3b. lipoteichoic acid has antigenic properties to stimulate a specific immune response |
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what is the capsule of strep pyogenes made of?
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Hyaluronic acid
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What is used to detect step pyogenes in Resporatory testing kits?
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T antigen virulence factor
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What are some of strep pyogenes virulence factors?
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streptolysin (O)
streptodornase NADase streptokinase cell envelope protease (inactivates IL 8) |
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What are the steps in the pathogenesis of strep pyogenes?
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1) Encounter
2)Spread 3) Damage |
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how is strep pyogenes encountered?
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Direct contact with oral secretions
Respiratory droplets |
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how is strep pyogenes spead?
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It encounters the mucosal epithelial cell; ressist phagocytosis through the action of M proteins on fibrils and inveades the tissue
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How does strep pyogenes cause cellular damage?
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Increase in the inflammatory response (increased PMNs and puss formation)
Hemolysins and other enzymes |
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What is the gold standard done for diagnosisng and detecting strep pyogenes?
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Throat culture and incubation with a bacitracin disc
(Most group A strep not resistant to bacitrin so growth will be inhibited in the areas surrounding the A disc) |
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What is sensitivity?
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The percent of positives that are really positive
(if the test is negative this will rule a diaganosis out!) TP/TP+FN |
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What is specificity?
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The percent of negtives that are really negative.
(if the test is positive it will rule the diagnosis in) TN/ TN+FP |
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What is the positive predictive value?
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the percent of true positives that are test positives
TP/TP+FP |
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What is a Negative Predictive Value?
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percent of true negatives that are test negatives
TN/ FN+TN |
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What is the treatment for strep pharyngitis infection?
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Long acting penicillin G for 10 days
Macrolides like azithromycyin and caphalosporins |
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What are some of the controversies in treating strep pyogenes?
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Noncompliance with patients
Group A strep infections may occur with Beta lactimase producing organisms that can infere resistance to penicillin Early treatment may increase the chances of reinfection (decrease Ab developement and less tissue penetration for antibiotic) |
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What is the causitive agent of Diptheria?
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Corynebacterium diptheriae
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In which demogrphic is Diptheria commonly presented and how is it spread?
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RARE disease but presents in infants and children
Transmission by droplet nucleii from other infected individuals |
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What are some of the clinical manifestation of Diptheria?
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"Bull Neck" Syndrome
Pseudomembrane formation sore throat, fever, pallor tachy and weakness peripheral vascular collapse and death if severe |
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What are some of the characteristics of Corynebacterium diptheriae?
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Irregular club shapped appearance
Metachromatic granules that stain with methylene blue Produces garlic smell on culture |
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What are some of the virulence factors for c.diptheriae?
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Endotoxin due to a lysogenic beta phage with tox+ gene
A and B feagment toxin: B fragment binds to cell receptor and is endocytosed. A fragment enters the cytoplasm to cause damage by blocking protein systesis with ADP ribosylation of elongation factors |
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Diptheria is a ____________. Toxin is absorbed in to _________________, destroys epithelium and incites a _______________
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Toxin mediated Disease
Mucous membranes strong inflammatory response |
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What forms the pseudomembranous film over the tonsils in diptheria?
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Necrotic epethelium that is embedded into the fibrin and the blood cells
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What is the treatment protocol for diptheria?
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Passive immunization with antitoxin
Penicillin Immunization with toxoids DTaP vaccination 2,4,6 mons and booster at 18 mos and 4-6 yrs |
