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Microbiology > 2c. Streptococcus > Flashcards

2c. Streptococcus Flashcards

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Biology 101 flashcards
1
Q

What type of Gram stain are Streptococcus?

A

G(+).

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2
Q

What general shape does Streptococcus have?

A

Chains or pairs of cocci.

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3
Q

Are Streptococcus Catalase positive?

A

No. They are all catalase negative.

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4
Q

How are Streptococcus serogrouped?

A

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

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5
Q

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

A

Human throat and skin.

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6
Q

Why are Streptococcus pneumoniae and viridans group not groupable?

A

Because they lack the carbohydrate cell wall antigens.

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7
Q

Which Streptococcus are beta hemolytic?

A

Streptococcus pyogenes, Streptococcus agalactiae.

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8
Q

Which Streptococcus are alpha hemolytic?

A

Streptococcus pneumoniae, and Streptococcus viridans group.

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9
Q

What is another name for Streptococcus faecalis?

A

Enterococcus faecalis. The enterococci belong to the Streptococcus family.

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10
Q

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

A

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

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11
Q

Which Streptococcus is Bacitracin-sensitive?

A

Streptococcus pyogenes (A disk).

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12
Q

Which Streptococcus is Bacitracin-resistant?

A

Streptococcus agalactiae (P disk).

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13
Q

Which Streptococcus is cAMP test positive?

A

Streptococcus agalactiae.

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14
Q

Which Streptococcus is bile-soluble?

A

Streptococcus pneumoniae.

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15
Q

Which Streptococcus is Lancefield Group A?

A

Streptococcus pyogenes.

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16
Q

Which Streptococcus is Lancefield Group B?

A

Streptococcus agalactiae.

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17
Q

Which Streptococcus is Lancefield Group D?

A

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

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18
Q

How is Group A Streptococcus spread?

A

By respiratory droplets or direct contact.

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19
Q

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

A

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

20
Q

What does the M protein do?

A

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

21
Q

What disease is M-12 protein associated with?

A

Acute glomerulonephritis.

22
Q

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

A

Streptolysin O is immunogenic, Streptolysin S is not.

23
Q

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

A

Breaks down fibrin clot.

24
Q

What does Streptococcal DNase do?

A

Liquefies pus, extension of lesion.

25
Q

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

A

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

26
Q

What does the Exotoxins A-C do?

A

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.

27
Q

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

A

Pharyngitis, Scarlet fever, Pyoderma/impetigo.

28
Q

What is the treatment for Group A Streptococcus?

A

Becta-lactam or erythromycin.

29
Q

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

A

With Penicillin.

30
Q

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

A

Streptococcus agalactiae.

31
Q

What does cAMP test-positive mean?

A

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

32
Q

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

A

Colonizes human vagina in 15-20% of women.

33
Q

What is the treatment for Group B Streptococcus?

A

Ampicillin with cefotazime or gentamicin.

34
Q

What is a preventitive measure against GBS?

A

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

35
Q

Which species of Streptococcus is inhibited by optochin?

A

S. pneumoniae.

36
Q

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

A

Human upper respiratory tract.

37
Q

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

A

Pneumolysin O.

38
Q

What type of pneumonia does S. pneumoniae cause?

A

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

39
Q

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

A

Penicillin G.

40
Q

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

A

Vancomycin +/- rifampin.

41
Q

What are two species of Viridans Streptococci?

A

S. sanguis, S. mutans.

42
Q

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

A

Human oropharynx (normal flora).

43
Q

Which species of Streptococcus causes dental caries and how?

A

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

44
Q

What is the treatment for Viridans Streptocci?

A

Penicillin G with aminoglycosides for endocarditis.

45
Q

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

A

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

Microbiology (7 decks)

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