Streptococcus & Enterococcus Flashcards
Introduction:
1. weak false-positive catalase reactions can be seen when growth is taken from media containing blood, owing to the ______
2. arranged in ____ or ____
3. first described by _____
- did not directly identify but based it on s/s of _______
4. streptos =
5. coccus
- peroxidase activity of hemoglobin
- pairs or chains
- Hippocrates
- Erysipelas - twisted
- berries
General Characteristics:
- oxygen requirement
- some are _____ - culture:
- poor on nutrients media such as _____
- color
- size
- slightly _____ colonies
- _____ (encapsulated) - biochem tests
- catalase =
- oxidase =
- gas production =
- fermentation =
- motility =
- facultative anaerobes
- capnophilic - culture:
- trypticase soy broth
- grayish
- pinpoint
- opaque
- mucoid - biochem tests
- negative
- negative
- negative
- nonfermenters
- non-motile
Classification of Streptococci
_____: based on temperature requirement
1. aka
2. divided the bacteria based on (3)
- introduced by:
***
1. includes all beta-hemolytic strains (S.pyogenes (A) & S.agalactiae (B))
- temp
2. not beta-hemolytic, cannot tolerate salt, cannot grow at high pH conc.
- temp
3. not clinically significant but associated w/ dairy products
- temp
4. can tolerate salt (halophilic), can grow at high pH conc.
- temp
Bergey’s Classification
1. Academic Classification
2. hemolytic reaction, carbohydrate antigen, phenotypic tests
- Sherman
***
1. Pyogenic
- only at 37C
2. Viridans
- 37C & 45C
3. Lactic
- 10C & 37C
4. Enterococcus
- 10C, 37C, & 45C
Classification of Streptococci
_____: based on hemolytic pattern
***
1. partial lysis of RBCs
- color
- bacteria
2. complete lysis of RBCs
- color
- bacteria
3. no lysis of RBCs
- color
- bacteria
4. small area of intact RBCs; surrounded by wider zone of complete hemolysis
- bacteria
Smith & Brown’s Classification
***
1. Alpha
- greenish
- S.pneumoniae
2. Beta
- clear
- S.pyogenes, S. agalactiae
3. Gamma
- no change
- Enterococcus
4. Alpha-prime
- S.bovis (Viridans)
Classification of Streptococci
_____: based on common c-carbohydrate found in the cell wall of streptococcus
1. introduced by ______
***
1. group A
- bacteria
- hemolysis
2. group B
- bacteria
- hemolysis
3. group C
- bacteria
- hemolysis
4. group D (non enterococcus)
- bacteria
- hemolysis
5. group D (enterococcus)
- bacteria
- hemolysis
Lancefield Classification
1. Rebecca Lancefield
***
1. group A
- S.pyogenes
- BETA
2. group B
- S.agalactiae
- BETA
3. group C
- S.dysgalactiae, S.equi
- BETA
4. group D (non enterococcus)
- S.bovis group
- ALPHA, NONE
5. group D (enterococcus)
- E.faecalis, E.faecium
- ALPHA, BETA, NONE
Lancefield Classification cont.
**these are not part of Lancefield classification
- Pneumococcus
- bacteria
- hemolysis - Viridans streptococcus
- bacteria (4)
- hemolysis
- Pneumococcus
- S.pneumoniae
- ALPHA - Viridans streptococcus
- Aginosus grp.; mutans grp.; mitis grp.; salivarius grp.
- BETA, ALPHA, NONE
______: most clinically significant under Lancefield group A as this is not part of the indigenous microbiota
- _______ and _______
- capsulated w/
- acquired thru ______ or _____
- invades _____ & ______
Streptococcus pyogenes
- fever-producing and flesh-eating bacteria
- hyaluronic acid
- contaminated droplets or direct skin contact)
- throat and skin
STREP PYOGENES VIRULENCE FACTOR
- major virulence factor
- renders the bacteria to be resistant in ______
- coated w/ ______ - fibrinolysis w/ Streptococcus pyogenes
- what causes the lysis of fibrin clot - degrade DNA which lowers viscosity of exudate
- aka - spreading factor which causes the hydrolysis hyaluronic acid
- M PROTEIN
- phagocytosis
- mecA gene - STREPTOKINASE
- plasmin - DNAse
- Thermonuclease - HYALURONIDASE
STREP PYOGENES VIRULENCE FACTOR
- responsible for subsurface hemolysis (oxygen-______)
- incubated ______
- detected by _____ - responsible for surface hemolysis (oxygen-______)
- causes lysis of ______ - adhesion molecules that mediate attachment to host epithelial cells (2)
- streptolysin O (oxygen-labile)
- anaerobically
- antistreptolysin O test - streptolysin S (oxygen-stable)
- leukocytes - Protein F & Lipotechoic acid
STREP PYOGENES VIRULENCE FACTOR
- superantigen that causes T-cell proliferation
- aka
- increased _______ cytokines (red spreading rash)
- causes ______ - most common serotype seen in pharyngitis
- ERYTHROGENIC TOXIN
- Streptococcal Pyrogenic Exotoxins
- pro-inflammatory cytokines
- Streptococcal Toxic Shock Syndrome - M1 Serotype
