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18 Cards in this Set

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capsule
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
quellung reaction
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.
alpha hemolysis
PNEUMOCOCCUS & "VIRIDANS" STREPTOCOCCI are alpha hemolytic - less hemolytic than beta hemolytic
-greenish color on a blood agar plate
bile solubility
a procedure that differentiates Streptococcus pneumoniae from other )-hemolytic streptococci by demonstrating its susceptibility to lysis in the presence of bile.
optochin test
No growth around optochin treated disk
inulin fermentation
plant polysaccharide is degraded and fermented with the production of acid by pneumococci, but not by other streptococci.
autolysis
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.
pneumolysin
extracellular product of pneumococcus that contribute to it's virulence
Streptococcus Pneumoniae (pnneumococci)- Metabolism
1) Catalase
2) Facultative anaerobe
3)Alpha hemolytic
Streptococcus Pneumoniae (pnneumococci)- Virulence
Capsul (83 Serotypes)
Streptococcus Pneumoniae (pnneumococci)- Toxins
Pneumolysin: binds to cholesterol in host-cell membranes (but it's actual effect is unknown)
Streptococcus Pneumoniae (pnneumococci)- Treatment
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.
Streptococcus Pneumoniae (pnneumococci)- Diagnostics
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
Streptococcus Pneumoniae (pnneumococci)- Miscellaneous
Quellung Reaction: Technique used to detect encapsulated bacteria (such as S. pneumoniae & H. Influenzae.
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
Lancefield group D
2 subtypes:
1. Enterococci:
-streptococcus faecalis
-streptococcus faecium
2. Non-enterococci
-streptococcus bovis
-streptococcus equinus
TREATMENT
Enterococci uniformly penicillin resistant
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
"VIRIDANS" STREPTOCOCCI
-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