Deck 13: Streptococcus, Enterococcus, and Similar Organisms

Question 1

The drugs of choice for most Enterococcal infections are:

A)vancomycin and a penicillin.
B)clindamycin and vancomycin.
C)penicillin and an aminoglycoside.
D)septra.

Answer 1

C
Enterococci are intrinsically resistant to a wide array of antimicrobial agents,and they are generally resistant to killing by any of the single agents (e.g. ,ampicillin,vancomycin)that are bactericidal for most other gram-positive cocci.Therefore,effective bactericidal activity can only be achieved with the combination of a cell wall-active agent,such as ampicillin or vancomycin,and an aminoglycoside,such as gentamicin or streptomycin.

Question 2

Erythrogenic toxin,hyaluronidase enzyme,and hemolysins S and O are extracellular products of:

A)E.faecalis.
B)S.pneumoniae.
C)S.pyogenes.
D)S.agalactiae.

Answer 2

C
All of these descriptions are true of S.pyogenes.

Question 3

What morphologic feature is a major consideration in determining an identification scheme for streptococci?

A)Colony shape and color
B)Hemolytic pattern
C)Smell
D)Consistency

Answer 3

B
The cellular arrangement on Gram stain and the type of hemolysis are important considerations in the identification of streptococci.

Question 4

The development of acute rheumatic fever and subsequent valvular heart disease are problems that may be encountered by patients infected with:

A)Enterococcus faecalis.
B)S.pneumoniae.
C)S.pyogenes.
D)S.agalactiae.

Question 5

The colonial morphologic features of this organism resemble a donut as it ages,and it has a polysaccharide capsule that is responsible for its virulence.What two characteristics describe this organism?

A)b-hemolytic and susceptible to optochin
B)a-hemolytic and bile solubility-negative
C)g-hemolytic and resistant to optochin
D)a-hemolytic and bile solubility-positive

Question 6

Which species of bacteria is responsible for causing diseases such as rheumatic fever,glomerulonephritis,and exudative pharyngitis?

A)Streptococcus agalactiae
B)S.pyogenes
C)S.pneumoniae
D)Enterococcus

Question 7

Enterococci can be described as:

A)able to hydrolyze bile esculin.
B)usually b-hemolytic.
C)a major cause of pharyngitis.
D)often carrying an antiphagocytic capsule.

Question 8

Optochin,PYR,bile solubility,esculin,and 6.5% NaCl are tests most likely performed on a(n)_______ Streptococcus.

A)aalpha-hemolytic
B)bbeta-hemolytic
C)ggamma-hemolytic
D)non-hemolytic

Question 9

Generally speaking,nutritionally variant streptococci require what ingredient not found in most conventional media?

A)Vitamin B₆
B)Nalidixic acid and its components
C)Nicotinamide adenine dinucleotide (NAD)enrichment
D)Blood or blood products

Question 10

Which of the following organisms best describes a catalase-negative,gram-positive coccus that is b-hemolytic on sheep blood agar,and bacitracin positive?

A)Streptococcus pyogenes
B)Streptococcus pneumoniae
C)Staphylococcus epidermidis
D)Micrococcaceae spp.

Question 11

The development of glomerulonephritis is a problem that may be encountered by patients infected with:

A)E.faecalis.
B)S.pneumoniae.
C)S.pyogenes.
D)S.agalactiae.

Question 12

The bacterial species that can be described as able to hydrolyze hippurate,is b-hemolytic,is a major cause of neonatal meningitis and sepsis,and is a producer of the Christie,Atkins,Munch-Petersen (CAMP)factor is:

A)E.faecalis.
B)S.pneumoniae.
C)S.pyogenes.
D)S.agalactiae.

Question 13

The bacterial species that can be described as able to grow in 6.5% sodium chloride (NaCl)and 40% bile,is part of the normal fecal flora of animals and humans,displays g hemolysis,and is a major cause of nosocomial infections is:

A)E.faecalis.
B)S.pneumoniae.
C)S.pyogenes.
D)S.agalactiae.

Question 14

What name is given to the type of hemolysis that produces incomplete hemolysis and a greening discoloration of the medium?

A)b hemolysis
B)g hemolysis
C)a hemolysis
D)k hemolysis

Question 15

What name is given to the type of hemolysis that produces complete hemolysis and a clearing of the medium?

A)b hemolysis
B)g hemolysis
C)a hemolysis
D)k hemolysis

Question 16

Bacitracin,CAMP factor,PYR,and hippurate are tests most likely performed on a(n)_______ Streptococcus.

A)aalpha-hemolytic
B)bbeta-hemolytic
C)ggamma-hemolytic
D)non-hemolytic

Question 17

Differentiation of the pleomorphic strains of streptococci and the similar corynebacteria or lactobacilli can be best accomplished by:

A)examination of Gram stain of the colony.
B)vancomycin-susceptibility testing.
C)serologic testing.
D)examination of the morphologic features after growth in thioglycollate broth.

Question 18

When performing the CAMP test,what bacteria is steaked down the middle?

A)S.epidermidis
B)Staphylococcus aureus
C)S.pyogenes
D)E.faecalis

Question 19

The major etiologic agent of bacterial endocarditis in the United States is:

A)E.faecalis.
B)S.pneumoniae.
C)S.pyogenes.
D)Viridans streptococci.

Question 20

S.pneumoniae can be described as:

A)resistant to bile and optochin.
B)b-hemolytic on sheep blood agar
C)CAMP positive
D)often carrying an antiphagocytic capsule.

Question 21

Sheep Blood agar is "stabbed" when inoculating bacteria to enhance hemolysis caused by:

A)streptolysin O.
B)streptolysin S.
C)streptokinase.
D)hyaluronidase.