streptococcus Flashcards Preview

Bacteriology > streptococcus > Flashcards

Flashcards in streptococcus Deck (36)
Loading flashcards...
1
Q

do streptococcus persist in the environment?

A

no

2
Q

what is classification of streptococci based on?

A

based on hemolysis

3
Q

what king of bacteria are streptococcus?

A

pyogenic gram positive cocci

4
Q

where are streptococcus part of the normal flora

A
  • upper resp tract

- lower genitourinary tract

5
Q

are streptococcus catalase pos or neg?

A

catalase negative

6
Q

classification of streptococci based on serology:

A

-based on carb called Substance C on cell surface

7
Q

what is streptococci’s pyogenic group?

A

species that cause pyogenic infections in humans and animals

-generally beta hemolytic

8
Q

what is streptococci’s oral or viridans group?

A

primarily commensals on mucous membrane

-alpha hemolytic

9
Q

what is streptococci’s lactic group?

A

present in milk and milk products

10
Q

what is streptococci’s enteric group?

A

present in intestinal conents

11
Q

what are streptococci’s virulence factors?

A
  • adhesins : bind to a variety of extracellular matrix proteins of the host (fibrinogen, fibronectin, collagen etc)
  • coating of these cells masks sites for complement activation and thus decrease opsonization
12
Q

streptococci’s surface proteins

A
  • M protein bind to fibrinogen and imparts an antiphagocytic property and enhances adherence to host epithelial cells
  • FbsA protein
  • FOG protein
13
Q

streptococci’s capsule

A

S. pyogenesand S. equi produce capsule composed of hyaluronic acid

  • poor antigenic activity and is antiphagocytic
  • S. agalactae, S. porcinus, S. canis have capsules composed of poly saccharide and not hyaluronic acid
14
Q

streptococci’s cell wall components

A

-peptidoglycan and lipoteichoic acid: interact with macrophages to release proinflammatory cytokines

15
Q

streptococci’s hemolysins

A
  • streptolysin O (SLO): oxygen labile
    • pore-forming toxin
    • suilysin is the SLO of S. suis
  • streptolyin S: oxygen stable
    • responsible for beta hemolysis
    • cytolytic to macroohages, leukocytes, platelets, etc
16
Q

what does streptokinase do?

A

activates plasminogen to form plasmin

  • gene is located on prophage
  • plasmin is a proteolytic enzyme that acts on host proteins, including fibrin (dissolve blood clots)
17
Q

what are two other enzymes produces by streptococci

A
  • hyaluronidase

- DNAse

18
Q

what is streptococci’s pathogenesis

A
  • primarily cause pyogenic infections that affect skin, resp tract, repro tract and mammary gland
  • organisms may enter the blood to cause septicemia
  • toxemia and immune-mediated lesions are common sequel of the disease
19
Q

describe S. puogenes as a disease in humans

A

-beta hemolytic streptococci
-acute pharyngitis or strep
variety of skin infections (pyoderma)
-impetigo: benign infections of the superficial layers of skin result in crusty honey-colored lesions
-erysipelas and cellulitis: infections of the deeper layers of skin are called erysipelas and cellulitis

20
Q

what does S pneumoniae cause in humans

A

pneumonia, meningitis, and sepsis

21
Q

what species of streptococci cause bovine mastitis?

A
  • S. agalactiae
  • S. dysgalactiae
  • S. uberis
22
Q

what species of streptococci causes strangles?

A

S. equi subsp. equi

23
Q

what streptococci causes infection in pigs?

A

S. suis

24
Q

what bacteria causes chronic contagious mastisis?

A

S. agalactiae

25
Q

what is the mode of infection of S. agalactiae

A

via the teat

26
Q

what is the capsule of S. agalactiae

A

antiphagocytic activity

27
Q

what are the surface proteins on S. agalactiae

A

ones involved in adhesion, invasion and inhibition of phagocytosis

28
Q

what does CAMP factor do

A

potentiates the action of staphylococcal beta toxin

-has cytotoxic activaty against mammary tissue

29
Q

what are two pathogenic things about S. agalactiae

A
  • death of PMNs and release of lysosomal enzymes cause the tissue damage and inflammaion
  • fibrin plug formation in the smaller molk ducts lead to involution of secretory tissue and loss of milk production
30
Q

what is the treatment for S. agalactiae infections

A
  • highlysusceptible to penicillins

- treated with ‘blitz treatment’-milk is cultures and positive cows are treated

31
Q

what causes acute and subclinical mastitis in cows?

A

S. dysgalactiae

32
Q

what is the significance of S. dysgalactiae subsp equisimilis

A
  • beta hemolytic
  • abscesses in horses; arthritis, meningitis, endometritis, mastitis
  • joint infections of piglets
33
Q

how does S. dysgalactiae infect and animal

A
  • typically through and injury
  • opportunity infection
  • associated with other bacteria
34
Q

what bacteria are most commonly found isolated from joint infections of piglets?

A

S. dysgalactiae sub sp equisimilis

35
Q

where are S. uberis found?

A

commensal of cattle: tonsillar and intestinal, mucosal and epithelial cells
-20-30% of the cases of mastitis in US

36
Q

how does S. uberis enter the cows?

A
  • entry though the teat canal
  • organisms attach and proliferate and induce influx of neutrophils
  • edema and vacuolation of secretory cells
  • necrosis of the alveoli
  • severity varies