Deck 15: Streptococcus, Enterococcus, and Other Catalase-Negative, Gram-Positive Cocci

Question 1

What is the hemolysin responsible for hemolysis on SBA incubated anaerobically?

A)Hyaluronidase
B)Streptolysin O
C)Streptolysin D
D)Hemolysin O

Answer 1

B
A hemolysin responsible for hemolysis on SBA plates incubated anaerobically is streptolysin O.The O refers to the fact that this hemolysin is oxygen labile.

Question 2

Most doctors' offices use the rapid throat swab methods to identify Streptococcus pyogenes.If the test is positive, the physician treats the patient.What should happen if the test is negative?

A)The physician should treat the patient to be safe.
B)The physician should perform a throat culture.
C)The physician should repeat the rapid strep tests.
D)None of the above.

Answer 2

B
Although a positive finding allows the primary care provider to treat for S.pyogenes infections without waiting for culture results, a negative result necessitates a throat culture.This is because the sensitivity of direct detection methods for group A streptococci is not high enough to ensure that the negative result is not a false negative.

Question 3

Which of the following is the drug of choice for treating most streptococcal infections?

A)Erythromycin
B)Cephalothin
C)Penicillin
D)Gentamicin

Answer 3

C
Despite widespread use, penicillin is the drug of choice in treating most streptococcal infections.However, penicillin-resistant Streptococcus pneumoniae and viridans group isolates have been reported worldwide, and the incidence of penicillin-resistant S.pneumoniae seems to be increasing.

Question 4

What causes the red spreading rash in scarlet fever?

A)Hyaluronidase
B)Streptolysin O
C)Streptococcal pyrogenic exotoxins
D)Streptolysin S

Question 5

What is one of the most common diseases caused by streptococci?

A)Strep throat
B)Rheumatic fever
C)Acute glomerulonephritis
D)Scarlet fever

Question 6

What test presumptively differentiates b-hemolytic group A streptococci and nonhemolytic group D enterococci from other streptococcal species?

A)Bacitracin
B)Hippurate hydrolysis
C)PYR
D)Optochin

Question 7

What test is used as a presumptive identification of Streptococcus pneumoniae?

A)Optochin
B)Bacitracin
C)PYR
D)Hippurate hydrolysis

Question 8

All of the following are additional virulence factors associated with group A Streptococcus except:

A)enterotoxins.
B)hemolysins.
C)toxins.
D)enzymes.

Question 9

What test differentiates staphylococci from streptococci?

A)Catalase
B)Coagulase
C)b-Hemolysis
D)All of the above

Question 10

What is the name of the test presumptively used to identify group B streptococci?

A)CAMP
B)Lancefield
C)Bacitracin
D)Optochin

Question 11

Streptokinase is an enzyme produced by group A streptococci that:

A)breaks down staphylococci.
B)breaks down connective tissue.
C)produces a maculopapular rash in rheumatic fever.
D)lyses fibrin clots.

Question 12

Physiologic classification of streptococci divide the species into all the following groups except:

A)pyogenic streptococci.
B)lactococci.
C)b-hemolytic streptococci.
D)enterococci.

Question 13

Common schemes to classify streptococci include all the following except:

A)biochemical characteristics.
B)serologic grouping or typing of C carbohydrate.
C)physiologic characteristics.
D)flagellar antigens.

Question 14

The atmospheric conditions best suited to grow streptococci and enterococci are:

A)room air.
B)oxygen-free atmosphere.
C)high carbon dioxide concentration.
D)low carbon dioxide concentration.

Question 15

What is the inexpensive test used to presumptively identify Streptococcus pyogenes?

A)Optochin
B)Bacitracin
C)Nitrate
D)Citrate

Question 16

Skin or pyoderma infections with group A streptococci result in all the following syndromes except:

A)impetigo.
B)bullous impetigo.
C)cellulitis.
D)erysipelas.

Question 17

What two tests have been mainstays in identification schemes for the non-b-hemolytic, catalase-negative, gram-positive cocci?

A)Bacitracin and PYR
B)Hippurate hydrolysis and optochin
C)Nitrate and PYR
D)Bile esculin and salt tolerance

Question 18

What is the cell wall made of in streptococci and enterococci?

A)Lipopolysaccharide and carbohydrates
B)Protein A and phospholipids
C)Cholesterol and teichoic acid
D)Teichoic acid and peptidoglycan

Question 19

What is the cellular structure that Streptococcus pyogenes relies on for its virulence?

A)Peptidoglycan
B)Lipopolysaccharide
C)S antigens
D)M proteins

Question 20

What test can be used to differentiate Streptococcus agalactiae from other b-hemolytic streptococci?

A)Bacitracin
B)Hippurate hydrolysis
C)PYR
D)Optochin

Question 21

Streptococcus-like organisms that resemble enterococci and viridans streptococci include all the following except:

A)Moraxella.
B)Aerococcus.
C)Gemella.
D)Lactococcus.

Question 22

What is the drug of choice to treat Streptococcus pneumoniae?

A)Erythromycin
B)Penicillin
C)Zithromax
D)Chloramphenicol

Question 23

What is the drug of choice to treat group A streptococci when the patient cannot tolerate penicillin?

A)Penicillin
B)Erythromycin
C)Gentamicin
D)Cefoxitin

Question 24

What organism on sheep blood agar (SBA) has colonies that are small and transparent, surrounded by a wide zone of b-hemolysis?

A)Streptococcus agalactiae
B)Streptococcus pyogenes
C)Enterococcus
D)Viridans strep

Question 25

Streptococcus pneumoniae causes all the following infections except:

A)pharyngitis.
B)pneumonia.
C)bacteremia.
D)meningitis.

Question 26

What are two tests presumptively used to identify group B strep?

A)Hippurate hydrolysis and CAMP
B)Optochin and PYR
C)Bacitracin and PYR
D)PYR and hippurate hydrolysis

Question 27

Why do Streptococcus pneumoniae colonies on sheep blood agar (SBA) appear like a coin-raised edges and a depressed center?

A)The older growth at the center is smaller due to lack of nutrients.
B)The newer growths on the outside of the colony undergo the quellung reaction.
C)The older growth at the center is killed due to autolysis.
D)The newer growth has a thicker capsule, therefore it appears raised.

Question 28

What disease is produced by group A streptococci that is characterized by a rapidly progressing inflammation and necrosis of the skin, subcutaneous fat, and fascia?

A)Erysipelas
B)Scarlet fever
C)Necrotizing fasciitis
D)Streptococcal toxic shock syndrome

Question 29

Where are the viridans streptococci constituents of the normal flora?

A)Upper respiratory tract
B)Female genital tract
C)Gastrointestinal tract
D)All of the above

Question 30

A young girl goes to her doctor's office with a fever, headache, and a sore throat.The mother states the girl has a fever of 38.8° C (102° F).What test should the physician perform?

A)Throat culture
B)Antistreptolysin O
C)Optochin
D)Gram stain

Question 31

An 80-year-old woman is admitted from a nursing home where she has been sick with a cough and fever for 2 days.She is coughing up thick, rust-colored sputum.The physician prescribed penicillin, but she is not getting any better.What is her most probable diagnosis?

A)Viral pneumonia
B)Pneumococcal pneumonia with penicillin-resistant organism
C)Enterococcal pneumonia with vancomycin-resistant enterococci (VRE)
D)S.agalactiae infection

Question 32

What organism on sheep blood agar (SBA) has grayish white colonies surrounded by a small zone of b-hemolysis?

A)Viridans strep
B)Enterococcus
C)Streptococcus pyogenes
D)Streptococcus agalactiae

Question 33

Streptococcus agalactiae is a significant cause of:

A)pharyngitis.
B)cystitis.
C)invasive disease of the newborn.
D)vaginitis.

Question 34

What is VRE?

A)Vancomycin-ready erythromycin
B)Very-reliable erythromycin
C)Vancomycin-resistant enterococcus
D)Veocin-resistant enterococcus

Question 35

One major virulence factor for Streptococcus pneumoniae is:

A)hemolysin.
B)protease.
C)hyaluronidase.
D)capsular polysaccharide.

Question 36

What two tests are presumptively used to identify Enterococcus?

A)PYR and hippurate hydrolysis
B)Bile esculin and 6.5% NaCl broth
C)Bacitracin and PYR
D)Catalase and coagulase

Question 37

Two serious complications of an infection with group A streptococcal disease are:

A)toxic shock syndrome and scarlet fever.
B)gangrene and rheumatic fever.
C)acute glomerulonephritis and necrotizing fasciitis.
D)acute glomerulonephritis and rheumatic fever.