Streptococcus

Question 1

Are streptococcus gram positive or negative?

Answer 1

Positive

Question 2

Are streptococcus motile or non-motile?

Answer 2

Non-motile

Question 3

Are streptococcus spore forming?

Answer 3

No

Question 4

Comment on the growth of streptococcus on simple media?

Answer 4

They grow poorly on simple media

Question 5

Comment on the growth of streptococcus on media containing blood, serum or fermentable sugar?

Answer 5

They grow well

Question 6

Longer chains are formed
in?

Answer 6

Liquid media

Question 7

Liquid media forms what type of streptococcus chains?

Answer 7

Long chains

Question 8

Virulent strains of streptococcus are capsulated with …………… in the capsule

Answer 8

hyaluronic acid

Question 9

Pathogenic species of streptococcus live in the …… and ………of humans and other animals.

Answer 9

naso-pharynx and GI tract

Question 10

How many methods of classifying streptococcus are recognized?

Answer 10

3

Question 11

The recognized methods of classifying streptococcus are ?

Answer 11

1. Bergey’s
2. Brown’s
3. Lancefield

Question 12

Streptococci may be classified into how many groups using their type of haemolysis?

Answer 12

4

Question 13

Streptococci may be classified into groups using their type of haemolysis, list the groups?

Answer 13

1. Alpha
2. Beta
3. Gamma
4. Alpha prime

Question 14

Describe alpha haemolysis?

Answer 14

partial lysis of blood leaving a greenish discoloration of the culture medium surrounding the colony

Question 15

Describe Beta haemolysis?

Answer 15

complete lysis of blood leaving a clear zone of haemolysis around the colony

Question 16

Describe Gamma haemolysis?

Answer 16

no lysis at all around the colonies

Question 17

Describe Alpha prime haemolysis?

Answer 17

partial followed by complete haemolysis around the colonies

Question 18

List the factors that influence haemolysis?

Answer 18

Haemolysis is influenced by
1. type of media,
2. production of haemolysin O and S
3. type of blood
4. aerobic and anaerobic incubation

Question 19

An example of a specie in Lancefield group A?

Answer 19

Strep. Pyogenes

Question 20

Characteristics of lancefield group A streptococcus include?

Answer 20

It possesses capsule made up of hyaluronic acid (detectable only in young cultures, 1-2 hours old)

Question 21

Toxins produced by streptococcus are?

Answer 21

Streptolysin O, S and Erythrogenic (Dick) toxin.

Question 22

The highly antigenic and oxygen labile toxin is ?

Answer 22

Streptolysin O

Question 23

Non-antigenic oxygen stable toxin is ?

Answer 23

Streptolysin S

Question 24

Another name for Streptolysin S is ?

Answer 24

Leucocidin

Question 25

The toxins responsible for beta haemolysis are ?

Answer 25

Streptolysin O and S

Question 26

Beta haemolysis is produced by?

Answer 26

Streptolysin O and S

Question 27

Conditions that may increase beta haemolysis include ?

Answer 27

1. incubation under increased carbon dioxide. 2. Anaerobic incubation 3. Prolonged aerobic incubation followed by overnight refrigeration

Question 28

What is responsible for the rash of scarlet fever.

Answer 28

Erythrogenic (Dick) toxin

Question 29

……… is produced by a few strains which are lysogenized?

Answer 29

Erythrogenic (Dick) toxin.

Question 30

The main site of streptococcal infection is the?

Answer 30

Throat

Question 31

Infections caused by S. pyogenes include?

Answer 31

1. Purulent tonsilitis. (in older chidren and adults.) 2. Diffuse pharyngitis –in younger children . 3. Scarlet fever- due to erythrogenic toxin. 4. Superficial and wound infections. 5. Erysipelas-diffuse strep skin infection involving superficial lymphatics. 6. Puerperal sepsis. 7. Rheumatic fever.

Question 32

Features of rheumatic fever include?

Answer 32

1. Fever. 2. Myocarditis with mitral & aortic valve damage). 3. Arthritis- fleeting joint swellings. 4. Chorea-uncontrolled movements of extremities. 5. Subcutaneous nodules-rubbery nodules under the skin. 6. Rash (Erythema marginatum- i.e with defined red margin

Question 33

Complications of strep throat infection include?

Answer 33

1. Peritonsilar & retropharyngeal abscesses. 2. Diffuse cellulitis of the floor of the mouth known as ‘Ludwig angina’ 3. Spread to middle ear, chest and brain. 4. Acute glomerulonephritis –by serotype 2. 5. Rheumatism. 6 .Erythema nodosum

Question 34

Enterococci causes?

Answer 34

pyelitis & SBE.

Question 35

Viridans streptococci cause?

Answer 35

SBE

Question 36

Another name for Anaerobic streptococci ?

Answer 36

Peptostreptococci

Question 37

Anaerobic streptococci cause ?

Answer 37

They cause puerperal sepsis and wound infections.

Question 38

What genus is pneumococci?

Answer 38

Diplococcus

Question 39

What type of colonies does pneumococci produce ?

Answer 39

They produce mucoid colonies

Question 40

What type of haemolysis does pneumococci undergo?

Answer 40

Beta haemolysis

Question 41

Pneumococci are soluble in?

Answer 41

Bile

Question 42

Pneumococci ferments ?

Answer 42

Inulin

Question 43

Pneumococci are susceptible to ?

Answer 43

Optochin

Question 44

Neufeld (quellung) will test positive for ?

Answer 44

Pneumococci

Question 45

The habitat of pneumococci is ?

Answer 45

Upper respiratory tract

Question 46

In children pneumococci causes?

Answer 46

Acute pyogenic meningitis & Otitis media

Question 47

Treatment for pneumococci are?

Answer 47

Penicillin & sulphonamide.

Question 48

Prophylaxis for pneumococci is ?

Answer 48

Capsular polysaccharide vaccine

Question 49

The discolored area after alpha haemolysis contains?

Answer 49

Unlysed RBCs and a green colored metabolite of hemoglobin

Question 50

Lancefield antigens are given letters ?

Answer 50

A, B, C, D, E to S