Streptococcus Flashcards
Streptococcus
They belong to the family
STREPTOCOCCACEAE
Streptococcus
● Some species are part of the indigenous human microbiota
○ Some species are______
CAPNOPHILIC
Place in candle jar
Streptococcus
● Their growth is enhanced by____, _____ or _____ that is incorporated in culture media
blood, serum or glucose
● All streptococci except (2) the are included in the Lancefield
classification
VIRIDANS GROUP and S. pneumoniae
Streptococcus
MICROSCOPY:
Gram (+) spherical cells that are arranged in chains or pairs.
Streptococcus
CULTURE:
Appear grayish, pinpoint, and translucent to slightly opaque while some species have mucoid colonies
Streptococcus
BIOCHEMICAL TESTS:
Catalase (-)
Oxidase and Gas production (-)
non motile
ferments carbohydrates
Streptococcus
NOTORIOUS PATHOGENS:
Streptococcus pyogenes
Streptococcus pneumoniae
CLASSIFICATION OF STREPTOCOCCI
ACADEMIC/ BERGEY’S CLASSIFICATION
SMITH AND BROWN CLASSIFICATION
LANCEFIELD CLASSIFICATION
Classification
● Based on TEMPERATURE REQUIREMENT
ACADEMIC/ BERGEY’S CLASSIFICATION
Classification
● Based on HEMOL YTIC PATTERNS
SMITH AND BROWN CLASSIFICATION
Classification
● Based on the extraction of C CARBOHYDRATE from
streptococcal cell wall.
LANCEFIELD CLASSIFICATION
Staph vs strep
Colonies
Staph: Larger, mucoid
Strep: Small-medium, pinpoint (very evident zone of hemolysis)
Flesh eating bacteria
S. pyogenes
Meningitis
S. agalactiae
Only grows @ 37°C
Pyogenic group
Pyogenic group ate
● Mostly __-hemolytic
β
Pyogenic group includes
● S. pyogenes
● Groups C and G streptococci
● Can grow at 45°C & 37°C
Viridans group
Viridans group
● NOT PART of the lancefield
Group but some are___-hemolytic
α
● Can grow at 10°C & 37°C
Lactic group
Lactic group
●___-hemolytic and has
Lancefield N antigen
Non hemolytic
● Often found in dairy products
●_____, causes normal
coagulation and souring of milk
Lactic group
S. lactis
● Can grow at 10°C, 45°C & 37°C
Enterococcus group
Enterococcus
● Part of normal microbiota of the
human____
● ______
intestine
E. faecalis
ALPHA HEMOLYTIC STREPTOCOCCI
Describe and give 2 examples
● They have partial/ incomplete
hemolysis of red blood cells
around the colonies
● For the culture, greenish or incomplete hemolysis
● S. pneumoniae and Viridans group
BETA HEMOLYTIC STREPTOCOCCI
Description and examples
● Exhibit a complete lysis of red
blood cells
● Clear zone of hemolysis around
the colony
● S. pyogenes, S. agalactiae
GAMMA HEMOLYTIC STREPTOCOCCI
Description and examples
● Do not exhibit the lysis of red
blood cells
● The RBC surround the colony
are unaffected
● S. bovis or E. faecalis
Lancefield classification
________, the microbiologist who
developed the classification method
○ found out that the ______can be
extracted from he streptococcal cell wall by placing the organism in _____
and heating the suspension for____
Rebecca Lancefield
C carbohydrates
dilute acetic acid
10 minutes
● It is most significant in classifying and identifying beta-hemolytic streptococci
Lancefield classification
HEMOLYTIC PATTERN - B
LANCEFIELD GROUP
SPECIES
A - S. pyogenes
B - S. agalactiae
C - S. agalactiae subsp. equisimilis
HEMOLYTIC PATTERN
Alpha or Gamma
Alpha, Beta or Gamma
LANCEFIELD GROUP
SPECIES
D - S. bovis
D - Enterococci
HEMOLYTIC PATTERN
Alpha, Beta or Gamma
LANCEFIELD GROUP
SPECIES
None but some of the strains may have A, C, F, G or N
Viridans
pneumonia and viridans don’t have ___
C carbohydrates
LANCEFIELD GROUP SUGARS
GROUP A
GROUP B
GROUP C
N - acetylglucosamine
Rhamnose - glucosamine
Rhamnose - n - acetylglucosamine
LANCEFIELD GROUP SUGAR
GROUP D
Glycerol teichoic
LANCEFIELD GROUP SUGAR
GROUP F
Glucopyranosyl –N– acetylglucosamine
T or F
GAS
● It is not considered as part of the indigenous microbiota
● It is pathogenic to humanity
True
GAS
● It is acquired through_______ that are released through coughing or sneezing
● Highly resistant to____ and can be recovered from swabs several hours after the collection
CONTAMINATED DROPLETS
DRYING
GAS
The species for this group is Streptococcus pyogenes which is
________ and _______
(involves deeper tissues and organs)
FEVER-PRODUCING AND FLESH EATING BACTERIA
S. pyogenes
● The principal virulence factor is______
PROTEIN M
○ Attached to the peptidoglycan
○ Antiphagocytic
○ Adherence to the mucosal cells
Protein M of S. pyogenes
GAS
● Culture on BAP:
colonies are small, translucent,
smooth and exhibit well-defined beta hemolysis
GROUP A (ENZYMES AND TOXINS)
HEMOLYSINS
ENZYMES
TOXINS
STREPTOLYSIN O
STREPTOLYSIN S
DEOXYRIBONUCLEASE (DNase)
HYALURONIDASE
PYOGENIC TOXINS - Serotypes
A, B, C and F
○ Responsible for the subsurface
hemolysis on BAP that is
incubated anaerobically
STREPTOL YSIN O