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25 Cards in this Set
- Front
- Back
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which gram(+) is catalase(+)?
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staphylococci
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catalase?
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converts H2O2 (hydrogen peroxide used by macrophages and neutrophils) into H2O and O2
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how tell if an organism is catalase(+)?
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bubbles appear with application of H2O2
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beta-hemolytic strep?
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completely lyse RBCs to leave a clear zone of hemolysis around the colony
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alpha-hemolytic strep?
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partially lyse RBCs to leave a greenish discoloration of the culture medium
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gamma-hemolytic strep?
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unable to hemolyze RBCs;
aka non-hemolytic |
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how are strep classified?
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ability to hemolyze RBCs;
lancefield antigens (C carbohydrate found on the cell wall) |
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strep significant pathogens?
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group A
group B group D strep pneumoniae viridans group |
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GAS aka?
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strep pyogenes
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antigenic components of the streptococcal cell wall?
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C carbohydrate
M protein |
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M protein?
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a major virulence factor for GAS;
inhibits activation of complement and protects from phagocytosis; cells can generate antibodies against it |
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streptolysin O?
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streptococcal enzyme that destroys RBCs and WBCs;
antigenic |
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use of anti-streptolysin O titers?
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confirm recent GAS infection
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enzyme present in GAS strains that cause scarlet fever?
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pyrogenic exotoxin
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4 types of disease caused by GAS?
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streptococcal pharyngitis
streptococcal skin infections scarlet fever streptococcal toxic shock syndrome |
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delayed antibody mediated disease caused by GAS?
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rheumatic fever
glomerulonephritis |
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why perform rapid antigen detection test?
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exudative pharyngitis can also be caused by non-strep organisms;
additionally a swab should be sent for culture (more sensitive) |
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streptococcal pharyngitis?
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red swollen tonsils and pharynx;
purulent exudate on the tonsils; high temps; swollen lymph nodes; usually lasts 5 days |
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erysipelas?
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strep infection of the superficial skin, the dermis only;
raised, bright red rash with a sharp border that advances from the initial site of infection |
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pyoderma?
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pustule usually on the extremity or face;
breaks down after 4-6 days to form a thick crust; heals slowly to leave depigmented area |
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best treatment for necrotizing fasciitis?
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penicillin G
clindamycin |
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most likely suspect in necrotizing fasciitis?
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GAS with M protein but also:
staph clostridium Gm(-) enterics mixed infection |
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Fournier's gangrene?
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form of necrotizing fasciitis involving the male genital area and perineum;
often caused by mixed organisms but can be caused by strep pyogenes |
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scarlet fever?
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caused by GAS with pyrogenic toxin/erythrogenic toxin;
fever with rd rash that begins on the trunk and neck to then spread to extremities, sparing the face; may peel off in fine scales during healing |
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6 major manifestations of rheumatic fever?
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fever
myocarditis joint swlling chorea subcutaneous nodules rash (erythema marginatum) |
