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18 Cards in this Set
- Front
- Back
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capsule
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A hyaline polysaccharide coating around a fungal or bacterial cell. Bacteria may also have a polypeptide capsule or a slime layer around the cell.
In streptococcus pneumonae-CAPSULE IS MOST IMPORTANT VIRULANCE FACTOR |
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quellung reaction
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The quellung reaction is a useful and rapid method for detecting pneumococci directly in clinical specimens of many different types (e.g. sputum).
-antigenic type of their capsule is determined as well -The test is performed by mixing a loopful of a clinical specimen or a bacterial suspension together with anti-pneumococcal antiserum and methylene blue on a microscope slide and then examining the slide with a microscope using the oil immersion lens. In a reaction between a pneumococcus and homologous antiserum, the capsule swells and becomes more refractile, making it easier to see. |
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alpha hemolysis
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PNEUMOCOCCUS & "VIRIDANS" STREPTOCOCCI are alpha hemolytic - less hemolytic than beta hemolytic
-greenish color on a blood agar plate |
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bile solubility
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a procedure that differentiates Streptococcus pneumoniae from other )-hemolytic streptococci by demonstrating its susceptibility to lysis in the presence of bile.
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optochin test
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No growth around optochin treated disk
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inulin fermentation
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plant polysaccharide is degraded and fermented with the production of acid by pneumococci, but not by other streptococci.
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autolysis
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Destruction of cells as a result of a lysin formed in those cells or others in the same organism
Pneumococcus has a strong tendancy towards autolysis -It is due to this that aging cultures of the pneumococcus may stain Gram-negative or Gram-variable, even though this is really a Gram-positive species. |
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pneumolysin
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extracellular product of pneumococcus that contribute to it's virulence
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Streptococcus Pneumoniae (pnneumococci)- Metabolism
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1) Catalase
2) Facultative anaerobe 3)Alpha hemolytic |
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Streptococcus Pneumoniae (pnneumococci)- Virulence
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Capsul (83 Serotypes)
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Streptococcus Pneumoniae (pnneumococci)- Toxins
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Pneumolysin: binds to cholesterol in host-cell membranes (but it's actual effect is unknown)
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Streptococcus Pneumoniae (pnneumococci)- Treatment
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Before 1965 all pneumococci were very sensitive to penicillin. In that year strains of intermediate resistance level were first isolated. In 1977 high-level penicillin-resistant strains were detected. At present in the United States the prevalence of high-level penicillin-resistant pneumococci varies considerably with location, 0% to 22%. Up to one-third combined high- and medium-level penicillin resistance in U.S., even more in some other countries. Resistance is not due to penicillinase and is not plasmid mediated; it is due to chromosomal mutation, affecting PBP's.
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Streptococcus Pneumoniae (pnneumococci)- Diagnostics
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A. Gram Stain: Reveals gram + diplococci
B. Culture does not grow in the presence of: 1. Optochin 2. Bile C. Positive Quellung test: Swelling when tested against antiserum containing anti capsular Ab |
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Streptococcus Pneumoniae (pnneumococci)- Miscellaneous
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Quellung Reaction: Technique used to detect encapsulated bacteria (such as S. pneumoniae & H. Influenzae.
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Lancefield group D
2 subtypes: 1. Enterococci: -streptococcus faecalis -streptococcus faecium 2. Non-enterococci -streptococcus bovis -streptococcus equinus |
1. Catalase -
2. Facultative anaerobe 3. Alpha hemolytic |
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Lancefield group D
2 subtypes: 1. Enterococci: -streptococcus faecalis -streptococcus faecium 2. Non-enterococci -streptococcus bovis -streptococcus equinus TREATMENT |
Enterococci uniformly penicillin resistant
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Lancefield group D
2 subtypes: 1. Enterococci: -streptococcus faecalis -streptococcus faecium 2. Non-enterococci -streptococcus bovis -streptococcus equinus DIAGNOSTICS |
1) Gram stain shoes gram positive cocci in chains
2) Culture: A. Enterococci can be cultured in: -40% bile -6.5 % NACL -penicillin resistant B. Nonenterococci can grow only in bile -penicillin sensitive |
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"VIRIDANS" STREPTOCOCCI
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-designation that includes a large number of species of alpha hemolytic streptococci that cannot be classified by group-specific carbohydrate antigens
-Found in cavities -can cause endocarditis |
