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29 Cards in this Set
- Front
- Back
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Streptococci General Characteristics
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Gram positive cocci in chains or pairs
Aerobic/ Facultative anaerobe 1-2 microns in diameter Catalase negative |
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The first step in classification is based on
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Pattern of hemolysis on agar containing 5% sheep erythocytes
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The three types of Hemolysis
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Beta
Alpha Gamma |
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Beta
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Lysis of the RBC's by heomlysis causes complete clearing around the colony
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Alpha
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Peroxidases cause imcomplete hemolysis and a greening of the area around colony
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Gamma
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No hemolysis, but microbiologists love a greek or latin name
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The Lancefield System
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for grouping streptococci based on serological differences in cell wall carbohydrate.
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In the Lancefield System which groups are of particular significance?
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A, B, C, D, F, G
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Which organism is not groupable according to Lancefield system?
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S. pneumoniae
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Aglutination indicates...
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that an organism has the corresponding substance in the cell wall
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"Pyogenes" refer to
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the fact that infection may be "pyogenic" or pus-forming
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THE group A strep of human clinical significance
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Streptococcus pyogenes
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Group A Beta-Hemolytic strep
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S. pyogenes
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tiny gram + cocci in chains
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S. Pyogenes
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S. pyogenes is the cause of
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Strep throat (pharyngitis)
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Quinsy
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suppurative complication of strep throat. (killed George Washington)
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Ludwig's angina
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Cellulitis of the deep tissues of the neck
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Symptoms of Strep throat
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Yello-white exude on tonsils
Sore throat, fever |
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Diagnosing Strep throat
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rapid antigen-based testing is available but it is only about 80% sensitive
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An Erythrogenic toxin causes a body rash
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Scarlet Fever
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Streptococcal impetigo
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dark red or brown crusts
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Erysipelas
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Superficial skin infection that extends into the lymphatics
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Cellulitis
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A spreading infection of the connective tissue of the skin
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An infection of the middle ear
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Otitis Media
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Strep of the ear
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otitis media
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Necrotizing fasciitis
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flesh eating bacteria. Treatment is brutal. bad tissue must be removed because it provides a safe haven for the organism
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follow an untreated Group A Strep infection such as strep throat or scarlet fever
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Post-streptococcal sequalae
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The two main sequalae
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rheumatic fever and post-streptococcal glomerulonephitis
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acute rheumatic fever
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typically occurs about 3 weeks after untreated streptococcal pharyngitis.
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