streptococcus

Question 1

do streptococcus persist in the environment?

Answer 1

no

Question 2

what is classification of streptococci based on?

Answer 2

based on hemolysis

Question 3

what king of bacteria are streptococcus?

Answer 3

pyogenic gram positive cocci

Question 4

where are streptococcus part of the normal flora

Answer 4

• upper resp tract

- lower genitourinary tract

Question 5

are streptococcus catalase pos or neg?

Answer 5

catalase negative

Question 6

classification of streptococci based on serology:

Answer 6

-based on carb called Substance C on cell surface

Question 7

what is streptococci’s pyogenic group?

Answer 7

species that cause pyogenic infections in humans and animals

-generally beta hemolytic

Question 8

what is streptococci’s oral or viridans group?

Answer 8

primarily commensals on mucous membrane

-alpha hemolytic

Question 9

what is streptococci’s lactic group?

Answer 9

present in milk and milk products

Question 10

what is streptococci’s enteric group?

Answer 10

present in intestinal conents

Question 11

what are streptococci’s virulence factors?

Answer 11

• 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

Question 12

streptococci’s surface proteins

Answer 12

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

Question 13

streptococci’s capsule

Answer 13

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

Question 14

streptococci’s cell wall components

Answer 14

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

Question 15

streptococci’s hemolysins

Answer 15

• 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

Question 16

what does streptokinase do?

Answer 16

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)

Question 17

what are two other enzymes produces by streptococci

Answer 17

• hyaluronidase

- DNAse

Question 18

what is streptococci’s pathogenesis

Answer 18

• 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

Question 19

describe S. puogenes as a disease in humans

Answer 19

-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

Question 20

what does S pneumoniae cause in humans

Answer 20

pneumonia, meningitis, and sepsis

Question 21

what species of streptococci cause bovine mastitis?

Answer 21

• S. agalactiae
• S. dysgalactiae
• S. uberis

Question 22

what species of streptococci causes strangles?

Answer 22

S. equi subsp. equi

Question 23

what streptococci causes infection in pigs?

Answer 23

S. suis

Question 24

what bacteria causes chronic contagious mastisis?

Answer 24

S. agalactiae

Question 25

what is the mode of infection of S. agalactiae

Answer 25

via the teat

Question 26

what is the capsule of S. agalactiae

Answer 26

antiphagocytic activity

Question 27

what are the surface proteins on S. agalactiae

Answer 27

ones involved in adhesion, invasion and inhibition of phagocytosis

Question 28

what does CAMP factor do

Answer 28

potentiates the action of staphylococcal beta toxin

-has cytotoxic activaty against mammary tissue

Question 29

what are two pathogenic things about S. agalactiae

Answer 29

• 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

Question 30

what is the treatment for S. agalactiae infections

Answer 30

• highlysusceptible to penicillins

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

Question 31

what causes acute and subclinical mastitis in cows?

Answer 31

S. dysgalactiae

Question 32

what is the significance of S. dysgalactiae subsp equisimilis

Answer 32

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

Question 33

how does S. dysgalactiae infect and animal

Answer 33

• typically through and injury
• opportunity infection
• associated with other bacteria

Question 34

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

Answer 34

S. dysgalactiae sub sp equisimilis

Question 35

where are S. uberis found?

Answer 35

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

Question 36

how does S. uberis enter the cows?

Answer 36

• 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