Streptococci Flashcards Preview

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Flashcards in Streptococci Deck (25):
1

what are some characteristics of streptococci bacteria

gram positive (peptidoglycan), facultative anaerobes, non-spore forming

2

what are the 3 ways to classify stretococcus

hemolysis patterns
lancefield group
species

3

what are the 3 types of hemolysis patterns

alpha - partial hemolysis and green discoloration
beta - complete hemolysis
gamma - no hemolysis

4

what is the most prevalent disease of Group A streptococcal diseases

acute pharyngitis (strep throat)

5

how would you prevent acute rheumatic fever (ARF)

by treating primary disease of strep throat w/ penicilan
-ARF only comes after strep throat does not spontaneously come

6

what is the only site of infection post acute rheumatic fever (ARF)

pharynx

7

what disease follows strep throat, is caused by a group a streptococcus, and causes smoky urine

Acute post-streptococcal glomerulonephritis (APSGN)

8

how are group A streptococcus infections transmitted, what age group is most susceptible

person to person, school aged children

9

Group A infections cant penetrate intact skin so the must bind to mucous membrane using ______ ?

adhesins

10

what do GAS adhesins bind to on epithelial surfaces

fibronectin

11

what are streptococcus 2 most important virulence factors

streptokinase, and hylauropeptidase

12

what is the role of streptokinase

it allows bacteria to degrade/lyse blood clots

13

what are group a streptococcus 3 mechanisms to avoid phagocytosis

-M protein
-hyaluronic acid capsule
-C5a peptidase

14

what is C5a peptidase and how does it work

an anti-phagocytosis mechanism of GAS, and it inactivates phagocyte chemotaxins

15

what is M protein and how does it work

an anti-phagocytosis mechanism of GAS, and it binds to host proteins preventing normal immune defense

16

what is the hyaluronic acid capsule and how does it work

an anti-phagocytosis mechanism of GAS, and it makes the strep "slippery" so phagocytes have tough time attaching to it

17

what activates macrophages, causes T cells to release cytokines, and is responsible for the red rash of scarlet fever

superantigens

18

Group A and Group B streps both have what hemolysis pattern

Beta

19

what are some characteristics of Group B streps

-inhabit GI and female genital tracts
-have a polysaccharide capsule
-aerobic

20

Group D streps exhibit what kind of hemolysis pattern

alpha or gamma

21

enterococci and neneneterococci are what group of streps

Group D streps or the normal fora of GI and genitourinary tracts

22

what is the "worlds toughest pathogenic bacteria" and why

enterococci, because its resistant to most antibiotics and penicilan only inhabits this bacteria NOT KILL it

23

what strep is the most common cause of subacute bacterial endocarditis

viridans streptococci

24

what strep type is known as the "mutans" group and is responsible for dental caries

Viridans streptococci

25

how do viridans streps cause dental plaque

form polymers on sucrose then ferment sugar to lactic acid (demineralizes enamel)
-remain active at low pH