SPHERE

Question 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

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

Lysostaphin is used to differentiate Staphylococcus from which other genus?

A. Streptococcus
B. Stomatococcus
C. Micrococcus
D. Planococcus

Answer 3

C. Micrococcus

Question 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

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

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

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

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

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

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

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

The following results were observed by using a tube coagulase test:

Coagulase at 4 hours = +
DNase = +
Hemolysis on blood agar = β
Coagulase at 18 hours = Neg
Novobiocin = Sensitive (16-mm zone)
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

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
Cephalothin = R
Vancomycin = S
Ampicillin = S
Cefoxitin = R
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

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

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

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

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

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

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

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

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

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

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

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

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

β-Hemolytic streptococci, not of group A or B, usually exhibit which of the following reactions? A. Bacitracin susceptible, TMP-SMX resistant B. Bacitracin resistant, TMP-SMX resistant C. Bacitracin resistant, TMP-SMX susceptible D. Bacitracin susceptible or resistant, TMP-SMX susceptible

Answer 26

D. Bacitracin susceptible or resistant, TMP-SMX susceptible

Question 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

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

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

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

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

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

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

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

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

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 Bile solubility = Neg PYR = + Hippurate hydrolysis = ± 6.5% salt = + Bile esculin = + Bacitracin = Resistant SXT = 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

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

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 = + Hippurate hydrolysis = + SXT = Resistant PYR = + Bile solubility = Neg 6.5% salt = + A. Enterococcus faecalis B. Streptococcus pneumoniae C. Streptococcus bovis D. Group B streptococci

Answer 38

A. Enterococcus faecalis

Question 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

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

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

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

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

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

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

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

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

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

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 = + Maltose = + Sucrose = Neg Fructose = Neg Lactose = + A. Neisseria gonorrhoeae B. Neisseria sicca C. Neisseria flavescens D. Neisseria lactamica

Answer 49

D. Neisseria lactamica (N. lactamica is the only Neisseria species that grows on MTM that utilizes lactose.)

Question 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 = + DNase = + Glucose = Neg Lactose = Neg Fructose = Neg Oxidase = + Tributyrin hydrolysis = + Sucrose = Neg Maltose = Neg A. Moraxella catarrhalis B. Neisseria flavescens C. Neisseria sicca D. Neisseria elongata

Answer 50

A. Moraxella catarrhalis

Question 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

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

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

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