BACTE LEC STREP Flashcards
Streptococcus and Enterococcus spp. are usually ___________________ and __________________ cocci
Catalase-negative, and gram-positive cocci
The streptococcal cells are more likely to appear in chains when grown in __________________
broth cultures.
Most members of the genera Streptococcus and
Enterococcus behave like ________________________
facultative anaerobes.
Classifications of Streptococci
Bergey’s Academic Classification
Brown and Smith Classification
Lancefield Classification
classification based on physiologic divisions of Streptococcus
Bergey’s Academic Classification
Grows neither 45 deg C nor 10 degC but
grows at 11-44 deg C; ave. 37deg C
PYOGENIC
Examples of PYOGENIC
Streptococcus pyogenes
Grows at 45 deg C but not at 10 deg C
VIRIDIANS
Examples of VIRIDIANS
S. salivarius, S. mutans,S.
sanguis; S. anginosus, S.mutans
Grows at both 45deg C and 10deg C
ENTEROCOCCI
Examples of ENTEROCOCCI
Streptococcus faecalis
Grows at 10deg C but not at 45deg C
LACTIC
Examples of LACTIC
S. cremoris; S. lactis (agent of souring of milk/rancid)
Classification based on the presence of serologically active C- CHO polysaccharide
Lancefield’s Classification
Carbohydrate cell wall antigen composition of Group A and C in Lancefield Classification
rhamnose-N-acetylglucosamine
Carbohydrate cell wall antigen composition of Group B in Lancefield Classification
rhamnose-glucosamine polysaccharide
Carbohydrate cell wall antigen composition of Group D in Lancefield Classification
Glycerol teichoic acid containing alanine & glucose
Carbohydrate cell wall antigen composition of Group F in Lancefield Classification
glucopyrasonyl -N-acetylgalactosamine
Classification Based on hemolytic reaction of Streptococci on Blood Agar Plate
Smith and Brown Classification
Partial hemolysis of RBC; accompanied by
a greenish discoloration
ALPHA
example for ALPHA classification
S. pneumoniae;
S. viridans
Complete hemolysis of RBCs indicated by
a clear colorless zone of hemolysis
surrounding the colonies
BETA
example for BETA classification
S. Pyogenes
S. agalactiae
Non-hemolytic or indifferent
Streptococci. No hemolysis on RBCs
GAMMA
example for GAMMA classification
S. faecalis
has a cell wall structure similar to
that of other streptococci and gram-positive
bacteria.
S. pyogenes
Resist phagocytosis (resistance to infection) and
plays a role in adherence of the bacterial cell to
mucosal cells
M protein
VIRULENCE FACTORS OF Streptococcus pyogenes
-M protein
-Lipoteichoic acid
-Fibronectin binding protein
-Hyaluronic acid capsule
-Streptolysin O
-Streptolysin S
-Streptococcal pyrogenic exotoxins
most common
serotype seen in pharyngitis.
M1 serotype
More than ___ different serotypes of M protein
exist
80
mediate attachment
to host epithelial cells.
Adhesion molecules
affixed to proteins on
the bacterial surface, in concert with M proteins
Lipoteichoic acid
secures the attachment of streptococci to the oral mucosal cells.
Fibronectin binding protein
prevents opsonized phagocytosis by neutrophils or macrophages
Hyaluronic Acid Capsule
allows the bacterium to mask
its antigens and remain unrecognized by its
host.
Hyaluronic Acid Capsule
responsible for hemolysis on SBA
plates incubated anaerobically
Streptolysin O
The O in Streptolysin O refers to this hemolysin being __________________
oxygen labile
___________________ is highly immunogenic and infected individuals readily form antibodies to the hemolysin
Streptolysin O
Streptolysin O antibodies can be measured in the
_____________________
antistreptolysin O (ASO) test
test to determine whether
an individual has had a recent infection with S.
pyogenes.
antistreptolysin O (ASO) test
is oxygen stable, lyses
leukocytes, and is nonimmunogenic.
Streptolysin S
The hemolysis seen around colonies that have
been incubated aerobically is due to _____________________
streptolysin S.
Some strains of S. pyogenes cause a red spreading
rash, referred to as _______________________
scarlet fever
The most common clinical
manifestations of GAS infection
Bacterial Pharyngitis
Most cases of bacterial
pharyngitis are due to _____________________
S. pyogenes.
is most often seen in children between 5 and
15 years of age
“Strep throat”
“Strep throat” incubation
1-4 days
- Most common cause of acute
pharyngitis
– Classic Strep throat with red swollen tonsils and pharynx
– A purulent exudate on the tonsils, high temperature, and swollen
lymph nodes
Streptococcus pyogenes
an invasive infection characterized by
rapidly progressing inflammation and necrosis of the skin,
subcutaneous fat, and fascia
Necrotizing Fasciitis
is a condition in which the entire organ system collapses, leading to
death.
Streptococcal Toxic Shock Syndrome
GAS associated with streptococcal TSS produce a streptococcal
pyrogenic exotoxin, notably _____________
SpeA.
typically follows S. pyogenes pharyngitis. It is characterized by fever and inflammation
of the heart, joints, blood vessels, and subcutaneous
tissues.
Rheumatic fever
Two serious
complications, or sequelae, of GAS disease are _____________________
(1) rheumatic fever and
(2) acute glomerulonephritis.
SPECIMEN COLLECTION – SITE CONSIDERATIONS of Streptococcus pyogenes
OROPHARYNGEAL SWAB
OROPHARYNGEAL SWAB remains moist, no further
precautions need to be taken for specimen that
are cultured within ___________of collection
4 hours
Streptococcus pyogenes is highly resistant to desiccation and remains viable on a dry
swab for _________________
48 to 72 hours.
Cultural Characteristics:
colonies are transparent to translucent, convex or domed entire,
circular, shiny and surrounded by a wide zone of β-hemolysis.
Streptococcus pyogenes
a presumptive test which differentiates
group A from other β-hemolytic Streptococci
Bacitracin (Taxo A)
any zone of inhibition regardless of the diameter is a
____reaction for Streptococcus pyogenes
(+) Positive
Principle of Bacitracin (Taxo A)
based on the selective inhibition of the growth of
Group A streptococci by a paper disc containing 0.02 – 0.04 units of Bacitracin
Detect the organisms
ability to hydrolyze the substrate
L- pyrrolidonyl-beta-napthylamide
PYR test
PYR test BRIGHT RED END PRODUCT
(+) Positive for Streptococcus pyogenes
test for susceptibility for scarlet fever
Dicks Test
Dicks test will be tested for reaction after ___
24 hours
Test to Diagnose Scarlet Fever
Schultz-Charlton Reaction (Blanching Phenomenon)
based on the neutralization of erythrogenic
toxins when an antitoxin is injected into the skin
of a patient with scarlet fever skin rashes fade or
blanch (+)
Schultz-Charlton Reaction (Blanching Phenomenon)
used to diagnose whether the skin rashes are due
to scarlet fever or not
Schultz-Charlton Reaction (Blanching Phenomenon)
TREATMENT for Streptococcus pyogenes
- Intramuscular benzathine penicillin as single dose
– Oral penicillin V for 10 days
– For penicillin-allergic patients – erythromycin,
clindamycin and cephalexin
Streptococcus agalactiae
Virulence factors
- Sialic Acid Capsule
- Hemolysin
- CAMP Factor
- Neuraminidase
- DNase
- Hyaluronidase
- Protease
The capsule prevents
phagocytosis
Sialic acid capsule.
Loss of sialic acid = _______________________
loss of virulence
a pore-forming protein
secreted by Streptococcus agalactiae
- CAMP Factor (proteinB)
contribute to the invasiveness,
cleaves the terminal N-acetylneuraminic acid
Neuraminidase
facilitate colonization on mucosal surfaces by degrading S-IgA
Proteases
_____________ are the leading cause of death in infants in the
United States.
Group B Streptococci
Colonization of the vagina and rectal area with.
GBS is found in _____________________ of pregnant women.
10% to 30%
Culture Media for Group B Streptococci: Streptococcus agalactiae
- Todd-Hewitt broth
- StrepB Carrot Broth (SCB)
culture media that Produced orange or red pigment even after 6 hours of incubation for GBS
StrepB Carrot Broth (SCB
Cultural characteristics of GBS in Sheep Blood Agar
grayish white mucoid colonies surrounded by a small zone of β-hemolysis
The most useful tests for GBS are positive _______________________ These tests enable the organism to be readily
differentiated from other β-hemolytic streptococcal
isolates
hippurate hydrolysis and
CAMP tests.
A characteristic “arrowhead” hemolytic
pattern results when the organism is streaked perpendicularly to βhemolytic S.aureus.
CAMP (Christie, Atkins, and Munch-Peterson) test
Positive result for GBS in Hippurate test
purple colored product
Streptococcus agalactiae clinical response to antimicrobial therapy is
often poor despite heavy doses given. Some
clinicians recommend a combination of ______________________for treating GBS infections.
ampicillin and aminoglycoside
Alpha Hemolytic Streptococcus
Streptococcus viridans
Streptococcus pneumoniae
3 Main Infections Caused by Viridans Streptococci
Dental Infections
Endocarditis
Abscesses
Streptococcus viridans groups
(1) S. mitis group (including
pneumoniae, S. sanguis, S. oralis);
(2) S. mutans group
(3) S. salivarius group
(4) S. bovis group
(5) S. anginosus group
is a member of the S. mitis
group, but it is much more virulent than other members of the
group
Streptococcus pneumoniae
S. pneumoniae can express one of approximately ___ different
capsular types
90
PATHOGENESIS: Invasion of the Host Tissue of Streptococcus pneumoniae
- Neuraminidase
- Autolysin
- H2O2
- Pneumonysin O
As the colonies become older, autolytic
changes result in the _________________
of the colony
collapse of the center
PATHOGENESIS: Attachment to the Host Tissue of Streptococcus pneumoniae
- Proteases
- Pili
facilitate colonization on
mucosal surfaces by degrading S-IgA for S. pneumoniae
Proteases
contribute to colonization and increase
the formation of large amounts of TNF by
the Immune system for S. pneumoniae
Pili
a component of the cell wall of pneumococci which is a teichoic acid that
reacts with some components of the immune response resulting in the activation of some
nonspecific host immune responses
C-substance
Most common
pneumonia (Lobar)
Streptococcus pneumoniae
specimen used for Streptococcus pneumoniae
Specimens:
blood, sputum, swabs, pus and
Most widely used presumptive test for
differentiating S.pneumoniae from otheralphahemolytic streptococci (
Optochin Test
Optochin Test Contains _____________________
ethylhydrocupreine hydrochloride
Optochin Test is also known as
Taxo P
Positive reaction is a _________ mm zone of
inhibition using a _____ mm Optochin disk.
14-16, 6
Equivocal reaction for S. pneumoniae
Any zone of inhibition less than 14 mm is
questionable for pneumococci
*S. pneumoniae produce a self-lysing enzyme to inhibit the growth
*The presence of bile salt accelerate this process
Bile Solubility Test
Positive and negative reaction for Bile Solubility Test
appears as clearing in the presence of bile while negative test appears as turbid
Based on the ability of the organism to ferment Inulin, a naturally occurring polysaccharide of plants
Inulin Fermentation Test
positive result for Inulin Fermentation Test
*Change of color of pH indicator and bubble/gas formation
which indicates that the sugar is fermented and acid
production results.
Mouse Virulence test result for Pneumococci vs Streptococci
P- dies within 16-48 hours
S- Wont die
Tests for differentiation of Pneumococci vs Streptococci
- Mouse Virulence Test
- Inulin Fermentation Test
- Bile solubility Test
- Optochin Test
- Neufield-Quellang Capsular Swelling Test
Inulin Fermentation test result for Pneumococci vs Streptococci
P- Fermenter
S- Non-fermenter
Bile solubility Test result for Pneumococci vs Streptococci
P- bile soluble
S- insoluble
Optochin Test result for Pneumococci vs Streptococci
P- Susceptible
S- resistant
Neufield-Quellang Capsular Swelling Test result for Pneumococci vs Streptococci
P- Swelling of capsule
S- No swelling
Bacterial groups in Alpha hemolytic Streptococcus
S. pneumoniae and S. viridans
Bacterial groups in Beta hemolytic Streptococcus
S. pyogenes and S. agalactiae
Bacterial groups in Gamma hemolytic Streptococcus
E. faecalis and E. faecium
Normal flora of the skin, upper respiratory, gastrointestinal and genitourinary tracts
Gamma-hemolytic:
Enterococci
Bile Esculin Test result for Enterococci vs Non-enterococci
E- (+)
NE- (+)
Growth w/ 6.5% NaCl Test result for Enterococci vs Non-enterococci
E- (+)
NE- (-)
PYR Test result for Enterococci vs Non-enterococci
E- (+)
NE- (-)
