2c. Streptococcus

Question 1

What type of Gram stain are Streptococcus?

Answer 1

G(+).

Question 2

What general shape does Streptococcus have?

Answer 2

Chains or pairs of cocci.

Question 3

Are Streptococcus Catalase positive?

Answer 3

No. They are all catalase negative.

Question 4

How are Streptococcus serogrouped?

Answer 4

They are serogrouped using know antibodies to the cell wall carbohydrates; Lancefield’s group A-O.

Question 5

Whrere in the human bodies is the reservoir for Group A Streptococcus?

Answer 5

Human throat and skin.

Question 6

Why are Streptococcus pneumoniae and viridans group not groupable?

Answer 6

Because they lack the carbohydrate cell wall antigens.

Question 7

Which Streptococcus are beta hemolytic?

Answer 7

Streptococcus pyogenes, Streptococcus agalactiae.

Question 8

Which Streptococcus are alpha hemolytic?

Answer 8

Streptococcus pneumoniae, and Streptococcus viridans group.

Question 9

What is another name for Streptococcus faecalis?

Answer 9

Enterococcus faecalis. The enterococci belong to the Streptococcus family.

Question 10

Which Streptococcus are PYR positive? What is the PYR test?

Answer 10

S. pyogenes and S. faecalis are both positive. The PYR test checks for the presence of pyrrolidonyl arylamidase.

Question 11

Which Streptococcus is Bacitracin-sensitive?

Answer 11

Streptococcus pyogenes (A disk).

Question 12

Which Streptococcus is Bacitracin-resistant?

Answer 12

Streptococcus agalactiae (P disk).

Question 13

Which Streptococcus is cAMP test positive?

Answer 13

Streptococcus agalactiae.

Question 14

Which Streptococcus is bile-soluble?

Answer 14

Streptococcus pneumoniae.

Question 15

Which Streptococcus is Lancefield Group A?

Answer 15

Streptococcus pyogenes.

Question 16

Which Streptococcus is Lancefield Group B?

Answer 16

Streptococcus agalactiae.

Question 17

Which Streptococcus is Lancefield Group D?

Answer 17

Streptococcus faecalis and Streptococcus bovis (which is non-enterococci).

Question 18

How is Group A Streptococcus spread?

Answer 18

By respiratory droplets or direct contact.

Question 19

Which Streptococcus produces a hyaluronic acid capsule and what does it do?

Answer 19

Streptococcus pyogenes. It is a polysaccharide that is non-immunogenic; it inhibits phagocytic uptake.

Question 20

What does the M protein do?

Answer 20

Virulence factor, antiphagocytic, used to TYPE group A strep.

Question 21

What disease is M-12 protein associated with?

Answer 21

Acute glomerulonephritis.

Question 22

Which streptolysin toxin is immunogenic? Which one isn’t?

Answer 22

Streptolysin O is immunogenic, Streptolysin S is not.

Question 23

Streptokinase is a spreading factor that is part of the Streptococcus toxins. What does it do?

Answer 23

Breaks down fibrin clot.

Question 24

What does Streptococcal DNase do?

Answer 24

Liquefies pus, extension of lesion.

Question 25

What does hyaluronidase do and for what pathology is it important?

Answer 25

Hydrolyzes the ground substances of the connective tissues; important to spread in cellulitis.

Question 26

What does the Exotoxins A-C do?

Answer 26

Secreted by S. pyogenes, causes fever and the rash of Scaler fever, inhibit liver clearance of endotoxin (from normal flora), creating shock-like conditions. It is also a superantigen, acitvating many helper T cells by bridgin T cell receptors and MHC class II markers without processed antigen.

Question 27

What are three acute (suppurative) disease that S. pyogenes can cause?

Answer 27

Pharyngitis, Scarlet fever, Pyoderma/impetigo.

Question 28

What is the treatment for Group A Streptococcus?

Answer 28

Becta-lactam or erythromycin.

Question 29

How do we prevent reccurent S. pyogenes pharyngitis in rheumatic fever patients?

Answer 29

With Penicillin.

Question 30

What species is part of the Group B Streptococci (GBS)?

Answer 30

Streptococcus agalactiae.

Question 31

What does cAMP test-positive mean?

Answer 31

cAMP factor is a polypeptide that "compliments" a Staph aureus sphingomyelinase to make an area of new complete beta-hemolysis.

Question 32

Where in the human body is the reservoir for S. agalactiae?

Answer 32

Colonizes human vagina in 15-20% of women.

Question 33

What is the treatment for Group B Streptococcus?

Answer 33

Ampicillin with cefotazime or gentamicin.

Question 34

What is a preventitive measure against GBS?

Answer 34

Treat mother prior to delivery if she has had a previous baby with GBS, has documented GBS colonization or prolonged rupture of membranes.

Question 35

Which species of Streptococcus is inhibited by optochin?

Answer 35

S. pneumoniae.

Question 36

Where in the human body is the reservoir for S. pneumoniae?

Answer 36

Human upper respiratory tract.

Question 37

What toxin of S. pneumoniae damages respiratory epithelium, inhibits leukocyte respiratory burst and inhibits classical complement fixation?

Answer 37

Pneumolysin O.

Question 38

What type of pneumonia does S. pneumoniae cause?

Answer 38

Typical pneumonia. Produces a lobar pneumonia with a productive cough, grows on blood agar, and usually responds well to penicillin treatment.

Question 39

What is the treatment for pneumonia caused by S. pneumoniae?

Answer 39

Penicillin G.

Question 40

What is the treatment for meningitis caused by S. pneumoniae?

Answer 40

Vancomycin +/- rifampin.

Question 41

What are two species of Viridans Streptococci?

Answer 41

S. sanguis, S. mutans.

Question 42

Where in the human body is the reservoir for Viridans Streptococci?

Answer 42

Human oropharynx (normal flora).

Question 43

Which species of Streptococcus causes dental caries and how?

Answer 43

S. mutans dextran-mediated adherence glues oral flora onto teeth, forming plaque and causing caries.

Question 44

What is the treatment for Viridans Streptocci?

Answer 44

Penicillin G with aminoglycosides for endocarditis.

Question 45

What can E. faecalis do that other Streptococci can't?

Answer 45

Hydrolyze esculin in 40% bile and 6.5 NaCl (bile esculin agar turns black).