Gram-positive bacteria

Question 1

Currently at least 40 species of staphylococci. Produces the enzyme c____ to clot blood plasma (fibrin clot formation around bacteria may protect from phagocytosis)

Answer 1

coagulase

Question 2

Coagulase can be +ve or -ve. What is the most important coagulase +ve?

Answer 2

Staphylococci aureus

Question 3

How is s.aureus spread?

Answer 3

Aerosol and touch

Question 4

What are the virulence factors of s. aureus?

Answer 4

Pore-forming toxins, proteases, Toxic Shock Syndrome toxin, Protein A (binds Igs in wrong direction)

Question 5

What is the main virulence factor of coagulase-negative staphylococci?

Answer 5

Ability to form persistent biofilms

Question 6

Streptococcus pyogenes forms c____

Answer 6

chains

Question 7

Ture or false: gram-positive cocci in chains is penicillin sensitive?

Answer 7

True

Question 8

Beta-c_____ lysis is due to the production of 2 pore-forming toxins

Answer 8

complete

Question 9

Alpha-p____ lysis is slightly green tinged due to production of H2O2 which reacts with haemoglobin to form green compound met-haemoglobin

Answer 9

partial

Question 10

Streptococci have c_____ cell surface antigens

Answer 10

carbohydrate

Question 11

Name some infections caused by S.pyogenes

Answer 11

Wound infections (cellulitis, puerperal fever)
Tonsillitis and pharyngitis,
Impetigo
Scarlet fever
Otitis media