Streptococci

Question 1

Are Streps gram -ve or gram +ve?

Answer 1

+ve

Question 2

Where are Streps found?

Answer 2

URT

Question 3

What can Streps cause in young animals?

Answer 3

Septicaemia

Question 4

Which parts parts do Streps cause disease?

Answer 4

Udder, urinary tract, skin

Question 5

Are streps haemolytic?

Answer 5

Yes

Question 6

Which type of enterococci can cause bacteraemia and nosocomial opportunistic infetions in humans and animals?

Answer 6

Vancomycin-resistant

Question 7

How long are the chains formed by Streps?

Answer 7

Variable

Question 8

Which type of cocci only form pairs?

Answer 8

Diplococci, esp straight from the animal in pus

Question 9

Which proteins do Streps have on the surface?

Answer 9

M protein and lipoproteins

Question 10

Which proteins are immunogenic?

Answer 10

M proteins

Question 11

What does the Strep capsule prevent?

Answer 11

C3b

Question 12

What is the capsule made of?

Answer 12

Hyaluronic acid

Question 13

What happens if no capsule?

Answer 13

Less pathogenic

Question 14

What do MSCRAMMs do?

Answer 14

Bind to host surface molecules

Question 15

How are MSCRAMMs anchored to cell wall?

Answer 15

LPXTG motif

Question 16

What does M protein bind?

Answer 16

Fibrinogen and fibronectin, and Fc of IgG and IgA

Question 17

What happens if M protein is mutated?

Answer 17

Less virulent

Question 18

What happens in M protein vaccines?

Answer 18

Only partial protection

Question 19

How can you predict Strep virulence?

Answer 19

Use M protein as show variability for immune escape

Question 20

What is C substance?

Answer 20

A cell wall carbohydrate

Question 21

Why do you use C substance not M protein for Lancefield grouping?

Answer 21

M protein is too cross-reactive

Question 22

Which letter are the Lancefield groups?

Answer 22

A-N

Question 23

What Lancefield group are equine Streps?

Answer 23

C

Question 24

What Lancefield group are most veterinary Streps?

Answer 24

B or C

Question 25

What do exotoxins mediate the change between?

Answer 25

Non-motile resp pathogen to motile systemic

Question 26

What do haemolysins do?

Answer 26

Streptolysins S and O (anaerobic vs aerobic) and form pores in cell membranes

Question 27

What type of haemolysis do all equine pathogens show?

Answer 27

Beta

Question 28

What kind of haemolysis do non-pathogenic Streps show?

Answer 28

None

Question 29

What do superantigens cause?

Answer 29

An unregulated T cell response

Question 30

What do Strep cultures look like?

Answer 30

On blood agar and 37 degrees, facultatively anaerobic, small colonies, mucoid if capsulated, matt if non-capsulated

Question 31

Are they catalase -ve or +ve?

Answer 31

-ve

Question 32

How many sugars do equine streps ferment?

Answer 32

At least one, other than S equi

Question 33

What are the 4 types of genome fingerprinting you can do?

Answer 33

Genome-wide (PFGE), large sub-genomic fragments (RFLP), sequences from sets of genes (MLST), sequences from single genes (SLST)

Question 34

Where is the reservoir for Streps?

Answer 34

Animals

Question 35

How long do Streps survive in the animal?

Answer 35

4-5 days

Question 36

How are new infections acquired?

Answer 36

Inhalation, fomites, direct transfer

Question 37

Where are neonatal infections from?

Answer 37

Dam

Question 38

What is the pathogenesis of Strep infections?

Answer 38

Adhesion to resp epithelium, colonisation of epithelium, invasion into lamina propria, evasion of phagocytosis, spreads into circulation and lymphatics, infections of remote organs

Question 39

What does recovery of Strep infection involve?

Answer 39

Phagocytosis (opsonising antibody)

Question 40

What is immunity like after recovery?

Answer 40

transient and variable because of M protein variation

Question 41

What is cross protection between serotypes like in Streps?

Answer 41

Little