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1

– they grow in the
presence of oxygen but cannot use oxygen for
respiration

Aerotolerant anaerobe

2

types of strep based on respiration (???)

Facultative anaerobe
• Aerotolerant anaerobe
• capnophilic

3

taxo A positive /
bacitracin(S)

group A strep

4

complications of group A [2]

Complications:
- rheumatic fever
- AGN

5

Infections of group A [3, PPT]

Infections:
- pharyngitis / strep throat
- pyodermal infections
- toxic shock syndrome

6

Test: detects activity
of L-pyrrolidonyl arylamidase or
pyrrolidonyl aminopeptidase

PYR

7

Meaning of PYR

(Pyrrolidonyl-anaphthylamide

8

group A strep antigenic structure
attached to the peptidoglycan of the cell wall and
extends to the cell surface
– essential for virulence

M protein

9

– Best defined virulence factor of group A strep
– Resists phagocytosis
– Adherence of bacterial cell to mucosal cells

M protein

10


Both are adhesion molecules that mediate
adherence to host epithelial cells. [group A[

Fibronectin-binding protein (protein F)
• Lipoteichoic acid

11

– Group A VF weakly
immunogenic; prevents opsonized
phagocytosis by neutrophils or macrophages;
allows bacterium to mask its antigens and
remain unrecognized by its host

Hyaluronic acid capsule

12

– hemolysis incubated anerobically;
oxygen labile; lyzes blood cells; highly
immunogenic, ASO test

SLO

13

– hemolysis incubated aerobically; oxygen
stable; lyzes WBC, nonimmunogenic

• SLS

14

Most common DNase [grp A]

DNase A,B

15

Pyodermal Infections of gp A[CISE]

Impetigo, Erysipelas, Cellulitis, scarlet fever

16


• Activates plasmin, turning itself into a tissue
degrader

Impetigo Caused by Streptococcus
pyogenes

17

- beta hemolytic (small zone)
- taxo A (-)
- CAMP test (+) / Hippurate hydrolysis(+)

Group B

18

Group B Virulence Factor
– prevents phagocytosis; ineffective
after opsonization; with sialic acid w/c inhibits
activation of the alternative pathway

• Capsule

19

Group B Virulence Factor
– most significant component of the
capsule; critical virulence determinant

• Sialic acid

20

Group B - No role in virulence [5]

• Hemolysin
• CAMP factor
• Dnase
• Hyaluronidase
• protease

21

Group B – Clinical Infections [2]

- pneumonia or meningitis with bacetermia
• Mastitis in cattle

22

Small-colony-forming-

S. anginosus (Viridans)

23

Large-colony-forming (w/ Group A) –

pyogenic
streptococci
– S. dysgalactiae subsp. equisimilis – upper
respiratory tract, vagina, skin, spectrum of
infections – like Group A

24

nonenterococcus

• Opportunistic infections

Group D Streptococcus

25

Species of Group D Streptococcus

– S. equinus
– S. bovis

26

Lab ID:
- Alpha or nonhemolytic
- PYR (-)
- psuedocatalase
- Bile esculin(+)
- 6.5% NaCl (-)

Group D Streptococcus

27


• Group D antigen
• Same infections as group D Strep

Enterococcus spp.

28

Lab ID
Varied hemolysis
- produce acid in CHO broth
- Arginine hydrolysis
- Tolerate 0.04 % tellurite (E. faecalis)
- Utilize pyruvate
- Produce acid from methyl-a-D-glucopyranoside (MGP)
- Growth around 100 ug efrotomycin disk
- motile
- PYR (+)
- Bile esculin(+)
- 6.5% NaCl(+), 45 degrees C, alkaline pH

Enterococcus spp.

29

#1 cause of bacterial pneumonia - lobar
(especially in the elderly and in those with
underlying disease) sinusitis, otitis media (most
common isolate in

s. pneumoniae

30

lab ID
- alpha hemolytic, CAP, brain-heart infusion agar,
trypticase soy agar with 5% sheep RBC;

s. pneumoniae

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