Strep Flashcards
fermenters but not gas producers
Strep and entero
Grow poorly in nutrient agar and tryptic soy broth
Strep and entero
• young-cultures have capsule in cell morphology
Strep
grayish, pinpoint, translucent to slightly opaque
• shows mucoid colonies
Strep
• some are aerotolerant
o microorganisms that grow in presence of oxygen but
unable to use oxygen for metabolism
Strep
Most notorious species – most clinically important species of strep?
Streptococcus pyogenes
• Streptococcus pneumoniae
o members of streptococcus that shows growth at 37°C
o usually produces rapidly
o mostly beta-hemolyt
Pyogenic Group
growth at 37°C and 45°C
o species: Enterococcus faecalis
o mostly normal inhabitants of the upper respiratory tract
Viridans group
growth at lower temperatures (10°C & 37°C)
o often found in dairy products
o species: Streptococcus lactis
▪ an organism that can cause normal coagulation
of milk or dairy products which leads to soaring
Lactococci
10°C, 37°C, & 45°C)
o wide range of temperature where they can show growth
Enterococcus
it is encapsulated even the old culture
which is a protection from the extraction of
the C-carbohydrate from the cell wall
S.pneu
Strep that - does not belong to any Lancefield
classification
S.pneu
Strep? M protein is attached to the peptidoglycan of the cell wall
and extends to the cell surface
Streptococcus pyogenes or Group A Streptococcus (GAS)
Strep pyo: is the most common serotype seen in
pharyngitis
M1 serotype
In strep pyo, this causes inflammation of oral cavity
M1 serotype
Strep pyo: are adhesion molecules that
mediate attachment to host epithelial cells.
Fibronectin-binding protein (Protein F) and
Lipoteichoic acid
Strep pyo: prevents opsonized
phagocytosis by neutrophils or macrophages. It also
allows the bacterium to mask its antigens and remain
unrecognized by its host
Hyaluronic acid capsule
Strep pyo: responsible for hemolysis on Sheep
Blood Agar plates incubated anaerobically
Strep pyo: oxygen-labile exotoxin
o Streptolysin O –
Strep pyo; responsible for the beta-hemolysis observed on
blood agar plates that are incubated
anaerobically
▪ causes subsurface hemolysis
streptolysin O
Strep pyo: lyses leukocytes and is non-
immunogenic
Streptolysin S
is an enzyme that
solubilizes the ground substance of mammalian
connective tissues
▪ allows the movement of organisms in tissues
Hyaluronidase
Strep pyo: red spreading rash
▪ contributes to the invasiveness of the
microorganism
Streptococcal pyrogenic endotoxins/erythrogenic
toxins
Strep throat is most often seen in children between 5
and 15 years of age
Strep pyo
Skin or pyodermal infections include
impetigo, cellulitis, erysipelas, wound infection, or arthritis
Strep pyo: pyodermal infections
invasive
infection characterized by rapidly progressing inflammation and
necrosis of the skin, subcutaneous fat, and fascia
o rapid progression of inflammation and skin necrosis
o flesh-eating bacteria
Strep pyo: Necrotizing Fasciitis (Galloping gangrene
Entire organ system shuts down
o Root cause: strep throat that was not managed
immediately
Strep pyo: Streptococcal Toxic Shock Syndrome
a group of immune-mediated complications
that usually occurs following a streptococci infection
sequelae
2 types of Poststreptococcal sequelae: an inflammatory condition
that can affect different parts of the body
Rheumatic fever
2 types of Poststreptococcal sequelae: inflammatory disease of the renal glomeruli
- caused by the deposition of antibody and
antigen complex in the glomerulus
Acute Glomerulonephritis/Bright’s disease –
a punctuate exanthem overlying diffuse erythema
o communicable disease
Scarlet Fever (Scarlatina)
diffused red rash on the upper chest spread to
the trunk and extremities
▪ “strawberry-colored tongue”
- caused by competition
Strep pyo: Scarlet Fever (Scarlatina)
Anti-streptolysin O Test/Titer
Test/ASO Titer
Dick’s test
Diagnostic test for scarlet fever
Schultz-Charlton Test
Screening test to identify group A Streptococcus
Bacitracin Disk test/Taxo A (0.04 units
identifies Group A and B Streptococci
o Positive result: Group A and B are resistant
Sulfamethoxazole and Trimethoprim test (SXT)
o Positive result of PYR test
Cherry red color
Acid stable polysaccharide is located in the cell wall of what strep group?
Streptococcus agalactiae or Group B Streptococcus (GBS)
GBS: ▪ Serotypes Ia, IIb and II contain a terminal residue
of
Sialic acid
The capsule prevents phagocytosis but is ineffective
after opsonization
GBS
GBS: appears to be the most significant
component of the capsule and a critical virulence
determinanT
Sialic acid
used to differentiate Group A from Group B Strep
CAMP test
CAMP positive result
Arrow-head zone of B-hemolysis near
the growth of S. aureus
utilized to detect the presence of the enzyme
hippuricase or hippurate hydrolase
Hippurate hydrolysis test
Group that possesses the enzyme Hippuricase or Hippurate
hydrolase
GBS
First rgt of HH test
Sodium hippurate
Second rgt of HH test
Ninhydrin
Product of HH test
Hippuric acid
Positive reaction of Hh test
Purple coloration of the media after
adding Ninhydrin reagent
Most useful biochemical test for GBS
o Hippurate Hydrolysis
o CAMP Test
GBS sample for pregnant women should be inoculated into selective broth such as?
Todd-Hewitt broth containing 10 ug/mL colistin and
15 ug/mL nalidixic acid
• Neonatal Streptococcal Infection is caused by?
GBS or step agalactiae
is a normal flora of the female genital tract
GBS
gram positive cocci in pairs, oval, lancet shape, and
facultative anaerobe
D. Streptococcus pneumoniae (Diplococcus/Pneumococcus)
The cell wall of S. pneumoniae contains an antigen,
referred to as
C.substance
In the presence of specific anticapsular serum, the
capsule swells called?
Quellung reaction for S.pneu
most useful
o Principle: In the presence of specific anticapsular serum,
the capsule swells
Neufeld Quellang Test (Capsular swelling test)
Diseases caused by S. pneumoniae:
mainly affects one or more lobes of the lungs
o bloody rust tinge sputum with large number of WBC
o alveoli are infected
Lobar pneumonia
They were previously classified as group D streptococci.
Entero
sometimes exhibit pseudo catalase reaction
o weak/minimal bubbling
Enterococci
They were previously classified as group D streptococci.
• Natural inhabitants of the intestinal tracts of human and animals
Entero
Can grow in extreme conditions:
Alkaline pH, high temperatures
up to 45°C, increased salt concentrations
Entero
Known to be resistant to multiple antimicrobial age
Entero
a type of bacteriocin found in gram positive
bacteria and usually important in quorum sensing
Cytolysin
medium containing tellurite is recommended for
E.faecalis
Mostly known to cause subacute bacterial endocarditis
Viridans Streptococci
Viridans strep is bile soluble or insoluble?
Insoluble
Viridans strep is optochin resistant or susceptible?
Resistant
presence of LAP is a characteristic of?
Viridans strep
