Micro-Gram-Positive and Gram-Negative Cocci

Question 1

1. The test used most often to separate the
   Micrococcaceae family from the Streptococcaceae
   family is:
   A. Bacitracin
   B. Catalase
   C. Hemolysis pattern
   D. All of these options

Answer 1

B. Catalase

Question 2

2. Micrococcus and Staphylococcus species are
   differentiated by which test(s)?
   A. Fermentation of glucose (OF tube)
   B. Catalase test
   C. Gram stain
   D. All of these options

Answer 2

A. Fermentation of glucose (OF tube)

Question 3

3. Lysostaphin is used to differentiate Staphylococcus
   from which other genus?
   A. Streptococcus
   B. Stomatococcus
   C. Micrococcus
   D. Planococcus

Answer 3

C. Micrococcus

Question 4

4. Which of the following tests is used routinely to
   identify Staphylococcus aureus?
   A. Slide coagulase test
   B. Tube coagulase test
   C. Latex agglutination
   D. All of these options

Answer 4

D. All of these options

Question 5

5. Which of the following enzymes contribute to the
   virulence of S. aureus?
   A. Urease and lecithinase
   B. Hyaluronidase and β-lactamase
   C. Lecithinase and catalase
   D. Cytochrome oxidase

Answer 5

B. Hyaluronidase and β-lactamase

Question 6

6. Toxic shock syndrome is attributed to
   infection with:
   A. Staphylococcus epidermidis
   B. Staphylococcus hominis
   C. Staphylococcus aureus
   D. Staphylococcus saprophyticus

Answer 6

C. Staphylococcus aureus

Question 7

7. Which Staphylococcus species, in addition to
   S. aureus, also produces coagulase?
   A. S. intermedius
   B. S. saprophyticus
   C. S. hominis
   D. All of these options

Answer 7

A. S. intermedius

Question 8

8. Staphylococcus epidermidis (coagulase negative) is
   recovered from which of the following sources?
   A. Prosthetic heart valves
   B. Intravenous catheters
   C. Urinary tract
   D. All of these options

Answer 8

D. All of these options

Question 9

9. Slime production is associated with which
   Staphylococcus species?
   A. S. aureus
   B. S. epidermidis
   C. S. intermedius
   D. S. saprophyticus

Answer 9

B. S. epidermidis

Question 10

10. Strains of Staphylococcus species resistant to the
    β-lactam antibiotics by standardized disk diffusion
    and broth microdilution susceptibility methods
    are called:
    A. Heteroresistant
    B. Bacteriophage group 52A
    C. Cross resistant
    D. Plasmid altered

Answer 10

A. Heteroresistant

Question 11

11. Staphylococcus saprophyticus is best differentiated
    from Staphylococcus epidermidis by resistance to:
    A. 5 μg of lysostaphin
    B. 5 μg of novobiocin
    C. 10 units of penicillin
    D. 0.04 unit of bacitracin

Answer 11

B. 5 μg of novobiocin

Question 12

12. The following results were observed by using a
    tube coagulase test:
    Coagulase at 4 hours = + Coagulase at 18 hours = Neg
    DNase = +
    Novobiocin = Sensitive
    (16-mm zone)
    Hemolysis on blood : agar = β

Mannitol salt plate = +(acid production)

What is the most probable identification?
A. Staphylococcus saprophyticus
B. Staphylococcus epidermidis
C. Staphylococcus aureus
D. Staphylococcus hominis

Answer 12

C. Staphylococcus aureus

Question 13

13. Staphylococcus aureus recovered from a wound
    culture gave the following antibiotic sensitivity
    pattern by the standardized Kirby–Bauer method
    (S = sensitive; R = resistant):
    Penicillin = R
    Ampicillin = S
    Cephalothin = R
    Cefoxitin = R
    Vancomycin = S
    Methicillin = R

Which is the drug of choice for treating this
infection?
A. Penicillin
B. Ampicillin
C. Cephalothin
D. Vancomycin

Answer 13

D. Vancomycin

Question 14

14. Which of the following tests should be used to
    differentiate Staphylococcus aureus from
    Staphylococcus intermedius?
    A. Acetoin
    B. Catalase
    C. Slide coagulase test
    D. Urease

Answer 14

A. Acetoin

Question 15

15. A gram-positive coccus recovered from a wound
    ulcer from a 31-year-old diabetic patient showed
    pale yellow, creamy, β-hemolytic colonies on
    blood agar. Given the following test results, what
    is the most likely identification?

Catalase = +
Glucose OF: positive open tube, negative sealed tube
Mannitol salt = Neg
Slide coagulase = Neg

A. Staphylococcus aureus
B. Staphylococcus epidermidis
C. Micrococcus spp.
D. Streptococcus spp.

Answer 15

C. Micrococcus spp.

Question 16

16. Urine cultured from the catheter of an 18-year-old
    female patient produced more than 100,000 col/mL
    on a CNA plate. Colonies were catalase positive,
    coagulase negative by the latex agglutination slide
    method as well as the tube coagulase test. The best
    single test for identification is:
    A. Lactose fermentation
    B. Urease
    C. Catalase
    D. Novobiocin susceptibility

Answer 16

D. Novobiocin susceptibility

Question 17

17. A Staphylococcus spp. recovered from a wound
    (cellulitis) was negative for the slide coagulase test
    (clumping factor) and negative for novobiocin
    resistance. The next test(s) needed for
    identification is (are):
    A. Tube coagulase test
    B. β-Hemolysis on blood agar
    C. Mannitol salt agar plate
    D. All of these options

Answer 17

D. All of these options

Question 18

18. Furazolidone (Furoxone) susceptibility is a test
    used to differentiate:
    A. Staphylococcus spp. from Micrococcus spp.
    B. Streptococcus spp. from Staphylococcus spp.
    C. Staphylococcus spp. from Pseudomonas spp.
    D. Streptococcus spp. from Micrococcus spp.

Answer 18

A. Staphylococcus spp. from Micrococcus spp.

Question 19

19. Bacitracin resistance (0.04 unit) is used to
    differentiate:
    A. Micrococcus spp. from Staphylococcus spp.
    B. Staphylococcus spp. from Neisseria spp.
    C. Planococcus spp. from Micrococcus spp.
    D. Staphylococcus spp. from Streptococcus spp.

Answer 19

A. Micrococcus spp. from Staphylococcus spp.

Question 20

20. Which of the following tests will rapidly
    differentiate micrococci from staphylococci?
    A. Catalase
    B. Coagulase
    C. Modified oxidase
    D. Novobiocin susceptibility

Answer 20

C. Modified oxidase

Question 21

21. Streptococcus species exhibit which of the following
    properties?
    A. Aerobic, oxidase positive, and catalase positive
    B. Facultative anaerobe, oxidase negative, catalase
    negative
    C. Facultative anaerobe, β-hemolytic, catalase
    positive
    D. May be α-, β-, or γ-hemolytic, catalase positive

Answer 21

B. Facultative anaerobe, oxidase negative, catalase
negative

Question 22

22. Which group of streptococci is associated with
    erythrogenic toxin production?
    A. Group A
    B. Group B
    C. Group C
    D. Group G

Answer 22

A. Group A

Question 23

23. A fourfold rise in titer of which antibody is the
    best indicator of a recent infection with group A
    β-hemolytic streptococci?
    A. Anti-streptolysin O
    B. Anti-streptolysin S
    C. Anti-A
    D. Anti-B

Answer 23

A. Anti-streptolysin O

Question 24

24. Bacitracin A disks (0.04 unit) are used for the
    presumptive identification of which group of
    β-hemolytic streptococci?
    A. Group A
    B. Group B
    C. Group C
    D. Group F

Answer 24

A. Group A

Question 25

25. Trimethoprim–sulfamethoxazole (SXT) disks are
    used along with bacitracin disks to differentiate
    which streptococci?
    A. α-Hemolytic streptococci
    B. β-Hemolytic streptococci
    C. Streptococcus pneumoniae
    D. Enterococcus faecalis

Answer 25

B. β-Hemolytic streptococci

Question 26

26. β-Hemolytic streptococci, not of group A or B,
    usually exhibit which of the following reactions?

Answer 26

D.

Question 27

27. A false-positive CAMP test for the presumptive
    identification of group B streptococci may occur
    if the plate is incubated in a(n):
    A. Candle jar or CO2 incubator
    B. Ambient air incubator
    C. 35°C incubator
    D. 37°C incubator

Answer 27

A. Candle jar or CO2 incubator

Question 28

28. Which test is used to differentiate the viridans
    streptococci from the group D streptococci and
    enterococci?
    A. Bacitracin disk test
    B. CAMP test
    C. Hippurate hydrolysis test
    D. Bile esculin test

Answer 28

D. Bile esculin test

Question 29

29. The bile solubility test causes the lysis of:
    A. Streptococcus bovis colonies on a blood agar plate
    B. Streptococcus pneumoniae colonies on a blood
    agar plate
    C. Group A streptococci in broth culture
    D. Group B streptococci in broth culture

Answer 29

B. Streptococcus pneumoniae colonies on a blood
agar plate

Question 30

30. S. pneumoniae and the viridans streptococci can be
    differentiated by which test?
    A. Optochin disk test, 5 μg/mL or less
    B. Bacitracin disk test, 0.04 unit
    C. CAMP test
    D. Bile esculin test

Answer 30

A. Optochin disk test, 5 μg/mL or less

Question 31

31. The salt tolerance test (6.5% salt broth) is used to
    presumptively identify:
    A. Streptococcus pneumoniae
    B. Streptococcus bovis
    C. Streptococcus equinus
    D. Enterococcus faecalis

Answer 31

D. Enterococcus faecalis

Question 32

32. In addition to Enterococcus faecalis, which other
    streptococci will grow in 6.5% salt broth?
    A. Group A streptococci
    B. Group B streptococci
    C. Streptococcus pneumoniae
    D. Group D streptococci (nonenterococci)

Answer 32

B. Group B streptococci

Question 33

33. The quellung test is used to identify which
    Streptococcus species?
    A. S. pyogenes
    B. S. agalactiae
    C. S. sanguis
    D. S. pneumoniae

Answer 33

D. S. pneumoniae

Question 34

34. The L-pyrrolidonyl-β-napthylamide (PYR)
    hydrolysis test is a presumptive test for which
    streptococci?
    A. Group A and D (enterococcus) streptococci
    B. Group A and B β-hemolytic streptococci
    C. Nongroup A or B β-hemolytic streptococci
    D. Streptococcus pneumoniae and group D
    streptococci (nonenterococcus

Answer 34

A. Group A and D (enterococcus) streptococci

Question 35

35. A pure culture of β-hemolytic streptococci
    recovered from a leg wound ulcer gave the
    following reactions:
    CAMP test = Neg
    Hippurate hydrolysis = Neg
    Bile esculin = Neg
    6.5% salt = Neg
    PYR = Neg
    Bacitracin = Resistant
    Optochin = Resistant
    SXT = Sensitive

The most likely identification is:
A. Group A streptococci
B. Group B streptococci
C. Enterococcus faecalis
D. Nongroup A, nongroup B, nongroup D
streptococci

Answer 35

D. Nongroup A, nongroup B, nongroup D
streptococci

Question 36

36. β-Hemolytic streptococci, more than 50,000 col/mL,
    were isolated from a urinary tract catheter urine
    specimen. Given the following reactions, what is the
    most likely identification?
    CAMP test = Neg
    Hippurate hydrolysis = ±
    Bile solubility = Neg
    6.5% salt = +
    PYR = +
    Bile esculin = +
    SXT = Resistant
    Bacitracin = Resistant
    Optochin = Resistant

A. Group A streptococci
B. Group B streptococci
C. Enterococcus faecalis
D. Nongroup A, nongroup B, nongroup D
streptococci

Answer 36

C. Enterococcus faecalis

Question 37

37. Nutritionally variant streptococci (NVS) require
    specific thiol compounds, cysteine, or the active
    form of vitamin B6. Which of the following tests
    supplies these requirements?
    A. CAMP test
    B. Bacitracin susceptibility test
    C. Bile solubility test
    D. Staphylococcal cross-streak test

Answer 37

D. Staphylococcal cross-streak test

Question 38

38. Many α-hemolytic streptococci recovered from a
    wound were found to be penicillin resistant. Given
    the following results, what is the most likely
    identification?
    Bile esculin = +
    PYR = +
    6.5% salt = +
    Hippurate
    Bile solubility= Neg
    hydrolysis = +
    SXT = Resistant

A. Enterococcus faecalis
B. Streptococcus pneumoniae
C. Streptococcus bovis
D. Group B streptococci

Answer 38

A. Enterococcus faecalis

Question 39

39. Which two tests best differentiate S. bovis
    (group D, nonenterococcus) from Streptococcus
    salivarius?
    A. Bile esculin and 6.5% salt broth
    B. Starch hydrolysis and acid production from
    mannitol
    C. Bacitracin and PYR
    D. Trimethoprim–sulfamethoxazole susceptibility
    and PYR

Answer 39

B. Starch hydrolysis and acid production from
mannitol

Question 40

40. Two blood cultures on a newborn grew β-hemolytic
    streptococci with the following reactions:
    CAMP test = +
    Hippurate hydrolysis = +
    Bile solubility = Neg
    6.5% salt = +
    Bacitracin = Resistant
    Bile esculin = Neg
    PYR = Neg
    Trimethoprim–sulfamethoxazole = Resistant

Which is the most likely identification?
A. Group A streptococci
B. Group B streptococci
C. Group D streptococci
D. Nongroup A, nongroup B, nongroup D
streptococci

Answer 40

B. Group B streptococci

Question 41

41. MTM medium is used primarily for the selective
    recovery of which organism from genital
    specimens?
    A. Neisseria gonorrhoeae
    B. Neisseria lactamica
    C. Neisseria sicca
    D. Neisseria flavescens

Answer 41

A. Neisseria gonorrhoeae

Question 42

42. Variation in colony types seen with fresh isolates
    of Neisseria gonorrhoeae and sometimes with
    Neisseria meningitidis are the result of:
    A. Multiple nutritional requirements
    B. Pili on the cell surface
    C. Use of a transparent medium
    D. All of these options

Answer 42

D. All of these options

Question 43

43. Gram-negative diplococci recovered from an
    MTM plate and giving a positive oxidase test
    can be presumptively identified as:
    A. Neisseria gonorrhoeae
    B. Neisseria meningitidis
    C. Neisseria lactamica
    D. All of these options

Answer 43

D. All of these options

Question 44

44. The Superoxol test is used as a rapid presumptive
    test for:
    A. Neisseria gonorrhoeae
    B. Neisseria meningitidis
    C. Neisseria lactamica
    D. Moraxella (Branhamella) catarrhalis

Answer 44

A. Neisseria gonorrhoeae

Question 45

45. Nonpathogenic Moraxella spp. capable of
    growing on selective media for Neisseria can be
    differentiated from Neisseria spp. by which test?
    A. Catalase test
    B. 10-unit penicillin disk
    C. Oxidase test
    D. Superoxol test

Answer 45

B. 10-unit penicillin disk

Question 46

46. A Gram stain of a urethral discharge from a
    man showing extracellular and intracellular
    gram-negative diplococci within segmented
    neutrophils is a presumptive identification for:
    A. Neisseria gonorrhoeae
    B. Neisseria meningitidis
    C. Moraxella (Branhamella) catarrhalis
    D. Neisseria lactamica

Answer 46

A. Neisseria gonorrhoeae

Question 47

47. The β-galactosidase test aids in the identification
    of which Neisseria species?
    A. N. lactamica
    B. N. meningitidis
    C. N. gonorrhoeae
    D. N. flavescens

Answer 47

A. N. lactamica

Question 48

48. Cystine tryptic digest (CTA) media used for
    identification of Neisseria spp. should be
    inoculated and cultured in:
    A. A CO2 incubator at 35°C for 24 hours
    B. A CO2 incubator at 42°C for up to 72 hours
    C. A nonCO2 incubator at 35°C for up to 72 hours
    D. An anaerobic incubator at 35°C for up to
    72 hours

Answer 48

C. A nonCO2 incubator at 35°C for up to 72 hours

Question 49

49. Culture on MTM media of a vaginal swab
    produced several colonies of gram-negative
    diplococci that were catalase and oxidase positive
    and Superoxol negative. Given the following
    carbohydrate reactions, select the most likely
    identification.
    Glucose = +
    Sucrose = Neg
    Lactose = +
    Maltose = +
    Fructose = Neg

A. Neisseria gonorrhoeae
B. Neisseria sicca
C. Neisseria flavescens
D. Neisseria lactamica

Answer 49

D. Neisseria lactamica

Question 50

50. Sputum from a patient with pneumonia produced
    many colonies of gram-negative diplococci on a
    chocolate plate that were also present in fewer
    numbers on MTM after 48 hours. Given the
    following results, what is the most likely
    identification?
    Catalase = +
    Oxidase = +
    DNase = +
    Tributyrin hydrolysis = +
    Glucose = Neg
    Sucrose = Neg
    Lactose = Neg
    Maltose = Neg
    Fructose = Neg

A. Moraxella catarrhalis
B. Neisseria flavescens
C. Neisseria sicca
D. Neisseria elongata

Answer 50

A. Moraxella catarrhalis

Question 51

51. Resistance to which drug categorizes a strain
    of Staphylococcus aureus as methicillin-resistant
    Staphylococcus aureus (MRSA)?
    A. Oxacillin
    B. Colistin
    C. Trimethoprim–sulfamethoxazole
    D. Tetracycline

Answer 51

A. Oxacillin

Question 52

52. An oxacillin-disk screen test is used to detect
    Streptococcus pneumonia resistance to penicillin.
    Using Mueller–Hinton agar with 5% sheep blood
    and a 1 μg oxacillin disk, what is the recommended
    inhibition zone size for penicillin susceptibility?
    A. ≥5 mm
    B. ≥10 mm
    C. ≥15 mm
    D. ≥20 mm

Answer 52

D. ≥20 mm

Question 53

53. Which one of the following organisms is a known
    producer of β-lactamase–producing strains, and
    should be tested (screened) by a commercial
    β-lactamase assay prior to susceptibility testing?
    A. Streptococcus pneumoniae
    B. Group B streptococci
    C. Enterococcus spp.
    D. Planococcus spp

Answer 53

C. Enterococcus spp.

Question 54

54. Which test is used for the determination of
    inducible clindamycin resistance in staphylococci
    and streptococci?
    A. E-test
    B. D-zone test
    C. A-test
    D. Camp test

Answer 54

B. D-zone test