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40 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the difference between exogenous and endogenous origin?
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Exogenous- a transmitted pathogen that is coming from outside the body. This can occur through direct contact with large secretions, or through droplet nuclei
Endogenous- Normally occuring flora that becomes pathogenic; gains access through a new location. |
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What is coryza?
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a series of symptoms that includes nasal discharge, obstruction, sneezing, watery eyes and a scratchy throat
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Name the five main families of viruses that can cause symptoms of the common cold.
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Picornavirus, orthomyxovirus, adenovirus, coronavirus, and paramyxovirus
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In temperate climates, what time of year do most colds tend to occur?
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Colder months (Autumn and Spring)
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Describe three types of transmission in the common cold.
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-Direct contact with infectious secretions on skin and environmental surfaces (nose to hand to nose)
-Contact with large airborne particles (respiratory secretions) -Infectious droplet nuclei (Influenzae) |
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When is the highest level of infection seen in the common cold?
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Days 2-3 of the infection
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What prevents the Rhinovirus from causing an invasive attack?
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The rhinovirus is temperature sensitive and thus only grows in the nasopharyngeal epithelium. It can not grow in deeper body tissues.
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What is it that the Rhinovirus attaches to on respiratory epithelium?
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The capsid adhesins attach mainly to ICAM-1.
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What causes the majority of symptoms associated with infections from cold viruses?
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They are caused by an increase in inflammatory mediators.
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What are the most common clinical symptoms of the common cold?
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nasal discharge, sneezing, sore throat, cough (mainly non-productive), fever (ususally only common in infants and young children)
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How long will symptoms typically last?
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24-72 hour incubation.
Symptoms peak in intensity within 2-3 days and are usually gone within one week. |
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How do we treat and prevent infections from viruses causing symptoms of the common cold?
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The number one rule: NO antibiotics
Rule number two: Treat symptoms (i.e. NSAIDS, saline gargle, de-congestant) Rule number three: OTC remedies are still highly unproven *Hand washing is still the most effective way to prevent infections* |
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A 5 year old child walks into your office complaining of a sore throat. You notice lesions on the throat. His mother tells you he has also been running a fever. What agent do you suspect?
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Herpangina (Coxsackie A virus)
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How long does Coxsackie A virus infection typically last?
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~7 Days
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Describe the progression of the infection.
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Punctate macules--(24 hours)->Erythematous papules-->Vesicular lesions with central ulceration
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Describe the type of hemolysis, and gram stain for Strep. pyogenes.
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S. Pyogenes is a Group A strep, which has Beta hemolysis. It is a GRAM POSITIVE Cocci (chain).
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What organic compound on the capsule of S. pyogenes is associated with invasive infections?
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hyaluronic acid
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Name the two most important fibrillar structures associated with S. pyogenes.
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M Protein
F protein |
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Describe the what the M protein does for S. pyogenes.
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The M protein is the major virulence factor for this bacteria. It binds to protein H which degrades C3b and disrupts complement binding. Can stimulate uptake by non-phagocytic cells.
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Describe the action of the F-protein.
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This allows for adhesion to fibronectin-coated epithelial cells.
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Name the two hemolysins associated with S. pyogenes and a general mechanism for both.
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Streptolysin O and Streptolysin S
-both of these enzymes appear to help break down RBC's in order to provide iron for growth. |
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What is the most common form of transmission of S. pyogenes?
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Direct contact through respiratory droplets (larger).
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A 10 year old child comes in to your office complaining of a sore throat. Her mother tells you that she has been running a fever for the past 2 days. Upon examination you see a purulent exudate and intense redness of the pharyngeal mucosa. What infection are you suspecting?
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Group A strep disease "strep throat"
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What is the common course of treatment for strep throat?
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Treatment should be given for a longer period of time. At least 10 days of penicillin or for someone allergic, erythromycin works as well.
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A child comes into your practice with a known strep infxn. Upon clinical examination a 'sand paper like' feel was seen on skin and the child's tongue looked like a strawberry.
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Scarlet Fever
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What is impetigo?
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A superficial skin infection that is often the result of a complicated strep infection. It presents with pimple-like papules and vesicles which break dwon over 4-6 days.
2-5 yo most susceptible |
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Who is most susceptible to invasive infections from Group A strep?
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Ages: 15-45
Underlying disease: IV drug use, HIT, diabetes, ischemia |
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What are three tissue manifestations of invasive infections from Group A strep?
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1. Erysipelas: inflammation of dermis layer of skin, in which cutaneous lymph tissue is affected
2. Cellulitis: acute spreading of inflammation through deep dermis and subcutaneous tissue (Generally seen in IV drug users, and patients with poor lymph drainage in upper/lower extremities) 3. Necrotizing Fasciitis: Involvement of deep subcutaneous tissue and fascial muscle planes or infxn of healthy muscle. |
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A patient walks into your office complaining of burning chest, painful joints, and a fever. He tells you that he recovered from a Strep infection just two weeks prior. Lab results come back positive for ASO. What is the most likely clinical diagnosis?
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Acute Rheumatic Fever
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What is the cause of ARF?
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It is believed to be caused by cross-reactive antibodies.
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Besides ARF, what other non-supporative S. pyogenes infection is possible?
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Acute Post-streptococcal Glomerulonephritis
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How long after a throat infxn would a person develop PSGN...skin infxn?
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Throat infection: ~10 days
Skin infection: ~21 days |
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What is the supposed cause of PSGN?
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It is caused mainly by antibody-antigen complexes that have become trapped in the glomeruli.
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Between ARF and PSGN, which can follow both repiratory tract AND skin infections?
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PSGN
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What is the proper culture series for Group A streptococcal infections?
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First a rapid antigen test can be done usually in the office. A positive test is highly specific, whereas a negative test is not very sensitive. A culture must be done on all negative tests. Culture results would be: Beta hemolysis
Gram stain: Gram positive cocci Catalase: Catalase negative |
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What is the usual course of treatment for Group A infections?
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10 days of penicillin or other beta-lactam. Erythromycin is used for patients with a penicillin alergy. Clindamycin is used for severe infxns to stop toxin production.
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What is diphtheria?
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It is an infection caused by an exotoxin that is produced by Corynebacterium diphtheriae, that causes a tough, pharyngeal membrane to develop.
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What kind of exotoxin is associated with diphtheria?
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A-B exotoxin. The A-B exotoxin uses its B(binding) protein in order to gain entry into a cell and then the A portion causes toxicity.
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Describe C. diphtheriae.
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Gram-positive rod
ORGANISM is non-invasive (toxin mediated disease) |
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What is a diphteroid?
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There are many species of Corynebacterium that colonize the skin normally and these may show up on a culture. They are of low pathogenicity.
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