8.5 Gram Pos and Gram Neg Cocci

Question 1

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

Answer 1

C. Staphylococcus aureus

Question 2

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 2

A. S. intermedius

Question 3

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

Answer 3

D. All of these options

Question 4

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

Answer 4

B. S. epidermidis

Question 5

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

Answer 5

A. Heteroresistant

Question 6

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

Answer 6

B. 5 ug of novobiocin

Question 7

The following results were observed by using a tube coagulase test:
-Coagulase at 4 hours=+
-DNase=+
-Hemolysis on blood agar=B
-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 7

C. Staphylococcus aureus

Question 8

Staphylococcus aureus recovered from a wound culture gave teh following antibiotic sensitivity pattern by the standardized Kirby-Bauer method (S=sensitive; R=resistant):
-Pencillin=R
-Cephalothin=R
-Vancomycin=S
-Ampicillin=R
-Cefoxitin=R
-Methicillin=R
Which is the drug of choice for treating this infection?
A. Penicillin
B. Ampicillin
C. Cephalothin
D. Vancomycin

Answer 8

D. Vancomycin

Question 9

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

Answer 9

A. Acetoin

Question 10

A gram-positive coccus recovered form a wound ulcer form a 31-year-old diabetic patient showed pale yellow, creamy, B-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 10

C. Micrococcus spp.

Question 11

Urine cultured from the catheter of an 18-year-old female patient produced more than 100,00 col/mL on a CNA plate. Colonies were catalase positive, coagulase negative by the late 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 11

D. Novobiocin susceptibility

Question 12

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. B-Hemolysis on blood agar
C. Mannitol salt agar plate
D. All of these options

Answer 12

D. All of these options

Question 13

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

Answer 13

A. Staphyloccus spp. from Micrococcus spp.

Question 14

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

Answer 14

A. Micrococcus spp. from Staphylococcus spp.

Question 15

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

Answer 15

C. Modified oxidase

Question 16

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, B-hemolytic, catalase positive
D. May be a-, B-, or y-hemolytic, catalase positive

Answer 16

B. Facultative anaerobe, oxidase negative, catalase negative

Question 17

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

Answer 17

A. Group A

Question 18

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

Answer 18

A. Anti-streptolysin O

Question 19

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

Answer 19

A. Group A

Question 20

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

Answer 20

B. B-Hemolytic streptococci

Question 21

B-Hemolytic streptococci, not of group A or B, usually exhibit which of the following reactions?
Bacitracin: Trimethoprim-sulfamethoxazole
A. Susceptible; Resistant
B. Resistant; Resistant
C. Resistant, Susceptible
D. Susceptible or resistant; Susceptible

Answer 21

D. Susceptible or resistant; Susceptible

Question 22

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. 35C incubator
D. 37C incubator

Answer 22

A. Candle jar or CO2 incubator

Question 23

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

Answer 23

D. Bile esculin test

Question 24

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

Answer 24

B. Streptococcus pneumoniae colonies on a blood agar plate

Question 25

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

Answer 25

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

Question 26

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 26

D. Enterococcus faecalis

Question 27

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

Answer 27

B. Group B streptococci

Question 28

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

Answer 28

D. S. pneumoniae

Question 29

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

Answer 29

A. Group A and D (enterococcus) streptococci

Question 30

A pure culture of B-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 30

D. Nongroup A, nongroup B, nongroup D streptococci

Question 31

B-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=+
-SXT=Resistant
-Optochin=Resistant
-Hippurate hydrolysis=+/-
-6.5% salt=+
-Bile esculin=+
-Bacitracin= Resistant
A. Group A streptococci
B. Group B streptococci
C. Enterococcus faecalis
D. Nongroup A, nongroup B, nongroup D streptococci

Answer 31

C. Enterococcus faecalis

Question 32

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

Answer 32

D. Staphylococcal cross-streak test

Question 33

Many a-hemolytic streptococci recovered form 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 33

A. Enterococcus faecalis

Question 34

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 form mannitol
C. Bacitracin and PYR
D. Trimethoprim-sulfamethoxazole susceptibility and PYR

Answer 34

B. Starch hydrolysis and acid production form mannitol

Question 35

Two blood cultures on a newborn grew B-hemolytic streptococci with the following reactions:
-CAMP test=+
-Bile solubility=Neg
-Bacitracin=Resistant
-PYR=Neg
-Trimethoprim-sulfamethoxazole: 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 35

B. Group B streptococci

Question 36

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

Answer 36

A. Neisseria gonorrhoeae

Question 37

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 37

D. All of these options

Question 38

Gram-negative diplococci recovered form 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 38

D. All of these options

Question 39

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 39

A. Neisseria gonorrhoeae

Question 40

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 40

B. 10-unit penicillin disk

Question 41

A Gram stain of a urethral discharge form 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 41

A. Neisseria gonorrhoeae

Question 42

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

Answer 42

A. N. lactamica

Question 43

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

Answer 43

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

Question 44

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 44

D. Neisseria lactamica

Question 45

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 45

A. Moraxella catarrhalis

Question 46

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 46

A. Oxacillin

Question 47

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

Answer 47

D.>/= 20mm

Question 48

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

Answer 48

C. Enterococcus spp.

Question 49

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 49

B. D-zone test

Question 50

Large gram-positive spore-forming rods growing on blood agar as large, raised, B-hemolytic colonies that spread and appear as frosted green-gray glass are most likely
A. Pseudomonas spp.
B. Bacillus spp.
C. Corynebacterium spp.
D. Listeria spp.

Answer 50

B. Bacillus spp.

Question 51

Bacillus anthracis and Bacillus cereus can best be differentiate by which test?
B-hemo; motility; oxidase; catalase; lecithinase; glucose
B.cereus: +; +; Neg: +; +; +
B.anthracis: Neg; Neg; Neg: +; +; +
A. Motility and B-hemolysis on a blood agar plate
B. Oxidase and B-hemolysis on a blood agar plate
C. Lecithinase and glucose
D. Lecithinase and catalase

Answer 51

A. Motility and B-hemolysis on a blood agar plate