Bacte lec Strep agalactiae and others Flashcards
Streptococcus agalactiae
Virulence factors (7)
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
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 (2)
o Todd-Hewitt broth
o StrepB Carrot Broth (SCB)
Cultural characteristics of GBS in Sheep Blood Agar
grayish white mucoid colonies surrounded by a small zone of β-hemolysis
Culture media that Produced orange or red pigment even after 6 hours of incubation for GBS
StrepB Carrot Broth (SCB
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 (2)
Streptococcus viridans
Streptococcus pneumoniae
3 Main Infections Caused by Viridans Streptococci
Dental Infections
Endocarditis
Abscesses
Streptococcus viridans groups (5)
(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
What Streptococcus spp.
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
S. pneumoniae
PATHOGENESIS: Invasion of the Host Tissue of Streptococcus pneumoniae (4)
Neuraminidase
Autolysin
H2O2
Pneumonysin O
S. pneumoniae
As the colonies become older, autolytic
changes result in the _________________
of the colony
collapse of the center
S. pneumoniae
PATHOGENESIS: Attachment to the Host Tissue of Streptococcus pneumoniae (2)
o Proteases
o 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
What Streptococcus spp.
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 is also known as
Taxo P
Optochin Test Contains _____________________
ethylhydrocupreine hydrochloride
Based on the ability of the organism to ferment Inulin, a naturally occurring polysaccharide of plants
Inulin Fermentation Test
Positive and negative reaction for Bile Solubility Test
appears as clearing in the presence of bile while negative test appears as turbid
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 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 (5)
o Mouse Virulence Test
o Inulin Fermentation Test
o Bile solubility Test
o Optochin Test
o 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 (2)
S. pneumoniae and S. viridans
Bacterial groups in Beta hemolytic Streptococcus (2)
S. pyogenes and S. agalactiae
Bacterial groups in Gamma hemolytic Streptococcus (2)
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- (-)
