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37 Cards in this Set
- Front
- Back
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Microscopically, streptococcus forms…
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… chains of cocci.
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Microscopically, staphylococcus forms…
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… clumps / clusters of cocci
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Which of these two, staph or strep, is catalase positive?
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Staph (remember the group picture of the hospital "staff" with cats down in front)
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What does being "alpha hemolytic" indicate?
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Bacteria only partially lyse blood… shows as green discoloration on blood agar plate.
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What does being "beta hemolytic" indicate?
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Bacteria completely lyse blood… shows as a clear zone on blood agar plate.
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What does being "gamma hemolytic" indicate?
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Bacteria cannot hemolyze RBCs… shows as no discoloration of blood agar plate.
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What are "Lancefield" antigens?
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A bacterial nomenclature scheme derived from analysis of the "C" carbohydrate of the cell wall.
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What is another name for Streptococcus Pyogenes?
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Group A Beta-Hemolytic Streptococci
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On which bacteria is the "M" protein found?
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Strep. Pyogenes (Group A Beta-Hemolytic Streptococci)
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What are the two streptolysin enzymes found in Strep Pyogenes?
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Streptolysin O and streptolysin S. (Both lyse RBCs and WBCs, but only O is antigenic)
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What is the exotoxin from Strep Pyogenes that causes scarlet fever?
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Pyrogenic Exotoxin (AKA Erythrogenic Exotoxin)… PS… this can also act as a superantigen
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What is the function of streptokinase from S. Pyogenes?
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Activates plasmin to break up fibrin clots.
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What are the 4 types of acute disease caused by local invasion or exotoxin release from S. Pyogenes?
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pharyngitis (classic strep throat), skin infections, scarlet fever, toxic shock syndrome… remember the kid who says "Mom, my throat hurst, my skin is disintegrating, my body is turning scarlet, and I'm going into toxic shock!"
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What are the 2 delayed antibody mediated diseases caused by S. Pyogenes?
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Rheumatic Fever, Glomerulonephritis
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What are 4 of the skin infections caused by S. Pyogenes?
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folliculitis, cellulitis, impetigo, necrotizing fasciitis
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What are the key features of Rheumatic Fever?
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It follows an untreated S. Pyogenes pharyngitis… produces, fever, myocarditis, joint swelling, chorea, subcutaneous nodules, and erythema marginatum… Remember John Trovolta dancing with inflammed joints and a broken heart in "Saturday Night Fever."
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What is the typical timeline for damage to heart valves by S. Pyogenes, vs. rheumatic valvular heart disease?
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The heart valves are damaged gradually after recurrent infections… years later (10-20) murmurs can be heard, and the rheumatic disease develops
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How often after an infection with S. Pyogenes does glomerulonephritis occur?
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About 1 week after either skin or pharyngeal infection with specific "nephritogenic" strains
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How does acute post-streptococcal glomerulonephritis present clinically?
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Tea-colored urine.
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What is another name for the Group B Beta Hemolytic Strep?
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S. Agalactiae
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Where is S. Agalactiae found and why is it important?
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Vagina… Causes meningitis in neonates. (Think… Group B… for Baby)
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What are the two Beta-Hemolytic streptococci?
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S. Pyogenes (Group A) and S. Agalactiae (Group B)
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What are the two Alpha-Hemolytic streptococci?
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S. Pneumoniae and S. Viridans (actually viridans is a whole group of them)
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What is the mneumonic for remembering S. Viridans?
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Viridans = Verde = Green… Think of green folliage growing on teeth that gets dislodged during dental work and starts growing vegetations on the mitral valve (which might have been previously damaged by S. Pyogenes).
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Which group does S. intermedius fall into, and what does it do clinically?
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S. Viridans group… causes abscesses (anaerobes… normally in GI tract)
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Which of the two alpha-hemolytic Strep groups have a capsule?
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S. Pneumoniae… detect with quellung test (see chapter 2)
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How do you distinguish between the two alpha-hemolytic groups?
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S. Pneumoniae is optochin sensitive and bile soluble… S. Viridans is NOT.
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S. Viridans and Staph Aureus both damage heart valves… what is the difference between them?
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S. Viridans slowly eats away at the valve... subacute myocarditis (usually that was previously damaged) and Staph Aureus rapidly destroys the valves... acute myocarditis
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S. Pneumoniae is to Parents as group B alpha hemolytic is to Babies in that...
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They cause meningitis in their respective targets.
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How does meningitis usually present in an adult?
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Stiff neck
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What are the principle diseases caused by S. Pneumonia
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Otitis media (particularly in children), and Meningitis (in adults)
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What are pneumococcal vaccines made of?
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Common capsular polysaccharide antigens.
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What are the differences between the two pneumococcal vaccines?
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Pneumovax (25 capsules) given to immune compromised, and Heptavalent Conjugate Vaccine (7 capsules) given to children age 3+.
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What are the two groups of gamma-hemolytic streptococci?
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Enterococci and non-enterococci (note: enterococci are now considered to be separate from streptococci entirely)
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Where are enterococci found and how are they infectious?
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Intestines (grow well in bile and in NaCl... normally harmless), Oportunistic bacteria that cause UTI's, Biliary Tract Infections, and subacute endocarditis… prey on weak patients in hospitals
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Enterococci have been found that are resistant to what drugs?
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Ampicillin and Vancomycin
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Non-enterococci have been linked to what disease?
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Colon Cancer
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