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
○ High antigenic and induces
antibody response
○ Serological test to be used to
detect recent infections with S.
pyogenes is the_______
STREPTOLYSIN O
ANTI-STREPTOLYSIN O (ASO)
= POSITIVE ASO
<200 Todd Units/ mL (IU/mL)
○ It is an oxygen - stable hemolysin and non-antigenic
○ Responsible for the surface
hemolysis on BAP that is
incubated
STREPTOLYSIN S
It lowers the viscosity of exudates giving the pathogens more mobility
DEOXYRIBONUCLEASE (DNase)
DEOXYRIBONUCLEASE (DNase)
Four types:
Antigenic Enzymes A, B, C, D
It causes fibrin clot lysis
STREPTOKINASE
A protein that binds to plasminogen and activates the production of plasmin.
Streptokinase
It activates a host blood factor that dissolves fibrin clots.
Streptokinase
Solubilizes the ground substance of mammalian tissues.
HYALURONIDASE
PYROGENIC TOXINS -
SEROTYPES A, B, C and F
Refers as super antigens
PYROGENIC TOXINS -
Pyrogenic toxins
Formerly known as______
ERYTHROGENIC TOXINS
degrades proteins and mediates
- rashes that are caused by Scarlet Fever.
EXOTOXIN B (Cysteine Protease)
OTHER VIRULENCE FACTOR
Protein F
Lipoteichoic Acid
Hyaluronic Acid Capsule
Hemolysins, Toxins & Enzymes
GROUP A (RELATED INFECTIONS/ DISEASE)
PHARYNGITIS OR TONSILLITIS (Strep
Throat)
SCARLET FEVER (SCARLATINA)
CELLULITIS
ERYSIPELAS
IMPETIGO
RHEUMATIC HEART FEVER
ACUTE GLOMERULONEPHRITIS
STREPTOCOCCAL TOXIC SHOCK SYNDROME
● It is spread by air droplets and
close contact
● Its diagnosis relies on the culture of specimen (throat swab) or direct antigen detection
PHARYNGITIS OR TONSILLITIS (Strep Throat)
● Caused by the release of pyrogenic toxins
● Associated with STRAWBERRY COLORED TONGUE
SCARLET FEVER ( SCARLATINA)
● Susceptibility test: (Erythrogenic Toxin Test) positive result shows erythema or redness of the skin
Scarlet fever
DICK’S TEST
Diagnostic Test:
(Anti-Erythrogenic Toxin Test)
positive result exhibits a BLANCHING PHENOMENON
Scarlet fever
SCHULTZ -
CHARLTON TEST
It is a contagious infection of
subcutaneous skin tissue that
is characterized by redness and
edema
Cellulitis
Acute infection of the dermal
layer of the skin with painful
swollen, reddish spot
Erysipelas
A skin infection that is caused
by a group A streptococcus
that may lead to necrotizing
fasciitis, which is also known as…
Impetigo
GALLOPING GANGRENE or FLESH EATING BACTERIA SYNDROME
● Characterized by fever, inflammation of the heart, joints and blood vessels
● Complication of PHARYNGITIS
RHEUMATIC HEART FEVER
A.K.A BRIGHT’S DISEASE
ACUTE GLOMERULONEPHRITIS
A.K.A BRIGHT’S DISEASE
ACUTE GLOMERULONEPHRITIS
Inflammatory disease of the renal glomeruli
Deposition of antigen-antibody
complex to the kidneys
ACUTE GLOMERULONEPHRITIS
Whole organ shuts down and
leads to death
STREPTOCOCCAL TOXIC SHOCK SYNDROME
GROUP A (LABORATORY TESTS)
BACITRACIN DISK TEST/ TAXO A
(0.04 units)
SULFAMETHOXAZOLE AND TRIMETHOPRIM TEST (SXT)
Pyrrolidonyl Arylamidase (PYR) test
● Differentiates S. pyogenes from other beta-hemolytic groups
● helpful in identifying group A
in throat cultures
BACITRACIN DISK TEST/ TAXO A
(0.04 units)
are also susceptible to Bacitracin
Groups C and G
● Group ____ are also resistant SXT
● Group___ are sensitive (Not so
important)
● (+) RESULT: Exhibits Resistance
SULFAMETHOXAZOLE AND TRIMETHOPRIM TEST (SXT)
B
C
● More specific than bacitracin
● Detects the presence of PYR
enzyme
● (+) RESULT:____
Pyrrolidonyl Arylamidase (PYR) test
Cherry Red Color
● These are part of the indigenous microbiota of the female genital tract and lower gastrointestinal tract
GROUP B – STREPTOCOCCI
● NOSOCOMIALL Y transmitted by unwashed hands of a mother or health care personally to the newborn or infant
GBS
● Causes infection on the fetus during the passage through the colonized birth canal and premature rupture of mother’s membranes
GBS
● Species for GBS group:
Streptococcus agalactiae
● As for the recommendation of CDC, all pregnant women should be screened for group B streptococci…
35 - 37 weeks of gestation
GBS RELATED INFECTIONS:
➔ Neonatal meningitis and sepsis
➔ Pneumonia
➔ Postpartum infection
➔ Urinary Tract Infection
➔ Endocarditis
GROUP B (LABORATORY TESTS)
CAMP TEST (Christie-Atkins-Munch-Petersen)
HIPPURATE HYDROLYSIS TEST
- Used to detect B-hemolysis
● Used to differentiate S. agalactiae from other beta-hemolytic streptococci
● Culture medium is____
●___ is for the reinforcement
of the reaction
CAMP TEST (Christie-Atkins-Munch-Petersen)
BAP
SAU
CAMP TEST
Reagent:
beta-lysin strip or beta-lysin
producing strain of SAU
● It is used to differentiate S. agalactiae from other beta-hemolytic streptococci
● S. agalactiae possesses the enzyme HIPPURICASE or HIPPURATE HYDROLASE
HIPPURATE HYDROLYSIS TEST
○ Breaks down sodium hippurate into…
benzoic acid and glycine
Hippurate Hydrolysis
Reagents:
Sodium Hippurate and
Ninhydrin (Purple Color)
CAMP TEST RESULT
(+) RESULT:
ARROWHEAD or BOW TIE SHAPED BETA HEMOLYSIS NEAR S. aureus growth
HIPPURATE HYDROL YSIS TEST
(+) RESULT:
(-) RESULT:
Purple color after adding ninhydrin
No Color Change
● They are also known as ALPHA PRIME
STREPTOCOCCI that lack the Lancefield antigens
○ Expected colonies are MUCOID
VIRIDANS STREPTOCOCCI
VIRIDANS STREPTOCOCCI
● They are the most common cause of
Subacute
Bacterial Endocarditis
Viridans
VIRULENCE FACTORS:
Capsule
cytolysin
extracellular dextran and adhesins
Viridans
LABORATORY RESULTS:
Bile insoluble
optochin-resistant (TAXO P)
does not grow in 6.5% NaCl
(+) LAP
(-) PYR
STREPTOCOCCUS VIRIDANS:
● S. anginosus
● S. mitis
● S. sanguinis
● S. salivarius
● S. mutans
VIRIDANS (LABORATORY TESTS)
● _____ is peptidase that hydrolyzes peptide bonds that are adjacent to a free amino group
LEUCINE AMINOPEPTIDASE (LAP) Test
LAP Test
○ Substrate:
○ Reagent:
○ End product:
Leucine-B-naphthylamide
p-dimethylaminocinnamaldehyde
(DMACA)
B-naphthylamine
(-) LAP:
Acrococcus and Leuconostoc
STREPTOCOCCUS PNEUMONIAE
● Also known as
diplococcus or pneumococcus
● Asymptomatic member of normal respiratory tract
● Causative agent of LUMBAR PNEUMONIAE
S. pneumoniae
● Most common cause of bacterial pneumonia in elderly and immunocompromised individuals.
S. pneumoniae
● Its cell wall contains an antigen that is referred to as______ which is not related to the C carbohydrate of the various lancefield groups
C SUBSTANCE
Pneumoniae
Pneumoniae
Principal Virulence Factor:
Microscopy:
______ SPUTUM indicates S. pneumoniae infection
CAPSULE (Polysaccharide)
Gram (+) cocci in pairs that are oval or lancet shaped
RUSTY-TINGED
STREPTOCOCCUS PNEUMONIAE (LABORATORY TESTS)
NEUFELD -QUELLUNG TEST (CAPSULAR SWELLING TEST)
FRANCIS SKIN TEST
COAGULATION TEST
● Allows the detection of S.
pneumoniae and serotyping
isolates
● The underlying principle is that
the capsule swells in the presence of specific anticapsular serum
NEUFELD - QUELLUNG TEST
(CAPSULAR SWELLING TEST)
● This test is used to detect the
presence of antibodies against
the pneumococci
FRANCIS SKIN TEST
● It uses the particle-bound
antibody to enhance the
visibility of the agglutination
reaction between the antigen
and antibody
COAGULATION TEST
ENTEROCOCCI
● They are formerly known as_____
because all the species produce the group D antigen
● The species are indigenous microbiota of human and animal…
group D enterococci
intestinal tracts
● NOT HIGHLY PATHOGENIC but are frequent cause of nosocomial infections
● They are RESISTANT to multiple antimicrobial agents
ENTEROCOCCI
Enterococci
The most common isolate:
Enterococcus faecalis
Enterococci
RELATED INFECTIONS:
➔ UTI
➔ Endocarditis
➔ Bacteremia
➔ Wound infection
Enterococci
LABORATORY TESTS:
(+) Bile esculin
PYR (+) growth in 6.5% NaC
