MLS

Sheep blood agar.

When processing throat swabs for a group A Streptococcus culture, the medium of choice is:

Rejected as unacceptable.

A 21 year old patient presents with pharyngitis. A throat swab is collected and submitted for anaerobic culture. This specimen should be:

LIM broth

A vaginal/rectal swab is collected from a pregnant patient to screen for group B Streptococcus colonization. What is the best medium to use for specimen inoculation?

incubated at 56c.

To quality control the autoclave, a vial of Bacillus stearothermophilus is autoclaved and should then be:

Bacterial suspension was not diluted to the proper concentration.

In a quality control procedure on a new batch of Mueller-Hinton plates using a stock culture of staphylococcus aureus, all the disk zone sizes are too small. The most likely reason for this is that the:

Novobiocin susceptibility

A urine Gram stain shows gram-positive cocci in clusters. Th organism tested catalase positive. To speciate this organism from the culture, the technician should perform a coagulase test and a/an:

Abiotrophia defectiva

The Gram stain from a blood culture shows gam-positive cocci in chains. No growth occurs on blood agar plates incubated both aerobically and anaerobically. Additional testing should be done to detect the presence of:

Bile solubility

Viridans streptococci can be differentiated from Streptococcus pneumoniae by:

Coagulase

A reliable test for distinguishing Staphylococcus aureus from other staphylococci is:

Streptococcus pneumoniae

The optochin (ethylhydrocupreine hydrochloride) disk is used for the identification of:

Group D Streptococcus

A gamma-hemolytic Streptococcus that blackens bile esculin agar but does not grow in 6.5% NaCl broth is most likely:

Catalse production and coagulase test.

Gram stain examiination from a blood culture bottle shows dark blue, spherical organisms in clusters. Growth on sheep blood agar shows small, round, pale yellow colonies. Further tests should include:

Bile esculin, PYR, acitracin, and hippurate.

Gram-positive cocci in chains are seen on a Gram stain from a blood culture. The organisms grows as a beta-hemolytic colony. Further tests that could be performed include:

in the genera Granulicatella and Abiotrophia

"Nutritionally deficient" streptococci are:

Group B streptococci

The organism most commonly associated with neonatal purulent meningitis is:

Streptococcus pyogenes

An important cause of acute exudative pharyngitis is:

Acute glomerulonephritis

Children who have infections with beta-hemolytic streptococci can develop:

Group A

A beta-hemolytic streptococci that is bacitracin-sensitive and CAMP-negative is:

Group B

A beta-hemolytic Streptococcus that is bacitracin-resistant CAMP positive is:

Latex antigen typing.

Group B, beta-hemolytic streptococci may be distinguished from other hemolytic streptococci by which of the following procedures?

Enterococci often show more antibiotic resistance than group D streptococci.

It is important to differentiate between Enterococcus and group D streptococci because:

Bile solubility

Streptococcus pneumoniae can be differentiated best from the viridans group of streptococci by:

Relatively resistant to penicillin.

Characteristically, enterococci are:

Hydrolysis os sodium hippurate

Which of the following would best differentiate Streptococcus agalactiae from Streptococcus pyogenes?

the most critical distinction between Staphylococcus aureus and other Staphylococcus is:

Coagulase production.

Streptococcus pyogenes.

Which of the following organisms is, to date, considered universally susceptible to penicillin?

Latex antigen typing.

A beta-hemolytic gram-positive coccus was isolated from the cerebrospinal fluid of a 2 day old infant with signs of meningitis. The isolate grew on sheep blood agar under aerobic conditions and was resistant to a bacitracin disc. Which of the following should be performed for the identification of the organism?

2-6 hours.

How many hours after eating contaminated food do initial symptoms of staphylococcal food poisoning typically occur?

There has been a break in proper skin preparation before drawing blood for culture

During the past month, Staphylococcus epidermidis has been isolated from blood cultures at 2-3 times the rate from the previous year. The most logical explanation for the increase in these isolates is that:

Furazolidone (100 ug/disk) susceptibility.

A yellow colony from a wound culture tested catalase-positive and coagulase-negative. The organism stained as gram-positive cocci in clusters. Which of the following tests would differentiate between a coagulase-negative Staphylococcus and Micrococcus?

CAMP test and S agalactiae

An isolate of unknown beta-hemolytic Streptococcus is streaked perpendicular to a streak of beta-lysin producing Staphylococcus aureus. After incubation a zone of arrowhead hemolysis is noted at the interface of the 2 streaks. What is the name of the test and the presumptive identification of the unknown Streptococcus?

Enterococcus faecalis

Which of the following may be used as a positive quality control organism for the bile esculin test?

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

B. Catalase

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

A. Fermentation of glucose (OF tube)

Lysostaphin is used to differentiate Staphylococcus from which other genus?

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

C. Micrococcus

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

D. All of these options

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

B. Hyaluronidase and β-lactamase

Toxic shock syndrome is attributed to infection with:

A. Staphylococcus epidermidis
B. Staphylococcus hominis
C. Staphylococcus aureus
D. Staphylococcus saprophyticus

C. Staphylococcus aureus

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

A. S. intermedius

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

D. All of these options

Slime production is associated with which Staphylococcus species?

A. S. aureus
B. S. epidermidis
C. S. intermedius
D. S. saprophyticus

B. S. epidermidis

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

A. Heteroresistant

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

B. 5 μg of novobiocin

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

C. Staphylococcus aureus

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

D. Vancomycin

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

A. Acetoin

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.

C. Micrococcus spp.

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

D. Novobiocin susceptibility

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

D. All of these options

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.

A. Staphylococcus spp. from Micrococcus spp.

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.

A. Micrococcus spp. from Staphylococcus spp.

Which of the following tests will rapidly differentiate micrococci from staphylococci?

A. Catalase
B. Coagulase
C. Modified oxidase
D. Novobiocin susceptibility

C. Modified oxidase

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

B. Facultative anaerobe, oxidase negative, catalase
negative

Which group of streptococci is associated with erythrogenic toxin production?

A. Group A
B. Group B
C. Group C
D. Group G

A. Group A

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

A. Anti-streptolysin O

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

A. Group A

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

B. β-Hemolytic streptococci

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

D. Bacitracin susceptible or resistant, TMP-SMX susceptible

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

A. Candle jar or CO2 incubator

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

D. Bile esculin test

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

B. Streptococcus pneumoniae colonies on a blood
agar plate

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

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

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

D. Enterococcus faecalis

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)

B. Group B streptococci

The quellung test is used to identify which Streptococcus species?

A. S. pyogenes
B. S. agalactiae
C. S. sanguis
D. S. pneumoniae

D. S. pneumoniae

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)

A. Group A and D (enterococcus) streptococci

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

D. Nongroup A, nongroup B, nongroup D streptococci

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

C. Enterococcus faecalis

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

D. Staphylococcal cross-streak test

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

A. Enterococcus faecalis

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

B. Starch hydrolysis and acid production from mannitol

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

B. Group B streptococci

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

A. Neisseria gonorrhoeae

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

D. All of these options

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

D. All of these options

The Superoxol test is used as a rapid presumptive test for:

A. Neisseria gonorrhoeae
B. Neisseria meningitidis
C. Neisseria lactamica
D. Moraxella (Branhamella) catarrhalis

A. Neisseria gonorrhoeae

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

B. 10-unit penicillin disk

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

A. Neisseria gonorrhoeae

The β-galactosidase test aids in the identification of which Neisseria species?

A. N. lactamica
B. N. meningitidis
C. N. gonorrhoeae
D. N. flavescens

A. N. lactamica

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

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

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

D. Neisseria lactamica

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

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

A. Moraxella catarrhalis

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

A. Oxacillin

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

D. ≥20 mm

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.

C. Enterococcus spp.

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

B. D-zone test

2. Which of the following organisms are PYR positive?
Selected Answer:

Group A Streptococcus
Group B Streptococcus
S. urinalis
Enterococcus spp.
a and c only
a, c, and d

a, c, and d

3. Which organism is not a normal inhabitant of the respiratory tract?

M. catarrhalis
N. meningitidis
N. mucosa
N. gonorrhoeae

N. gonorrhoeae

4. Which of the following is a leading sexually transmitted infection?

N. gonorrhoeae
N. meningitidis
N. sicca
N. mucosa

N. gonorrhoeae

5. Which of the following media is not acceptable for primary growth of N. gonorrhoeae?

Chocolate
Thayer-Martin
Blood
Martin-Lewis

Blood

6. Transcription is the:

Copying of DNA to RNA
Changing of DNA to RNA
Production of a complementary DNA
Completion of a protein sequence

Copying of DNA to RNA

7. Which organism is able to hydrolyze esculin and is a serious nosocomial pathogen?

S. bovis
S. mitis
E. faecalis
S. pneumonia

E. faecalis

8. What is the antibiotic of choice for beta-hemolytic Streptococcus ?

Penicillin
Tetracycline
Bacitracin
Vancomycin

Penicillin

9. Pathogenic M. catarrhalis grows best under which conditions?

Anaerobic atmosphere
42°C
Increased CO2
25oC

Increased CO2

10. Which of the following is a leading cause of fatal bacterial meningitis?

B. pertussis
M. catarrhalis
N. meningitidis
N. gonorrhoeae

N. meningitidis

11. Biologic false positives may occur in serologic assays for syphilis as a result of:

Failure to read the reaction at the correct time point
Inactivation of the patient's serum before analysis
Failure to bring samples and reagents to room temperature
Pathologic conditions, including other infectious diseases

Pathologic conditions, including other infectious diseases

12. N. gonorrhoeae can be differentiated from N. meningitidis by:

Dextrose fermentation
Maltose fermentation
Lactose fermentation
Nitrate reduction

Maltose fermentation

13. Which organism produces the CAMP factor enhancing beta-hemolysis in the presence of the S. aureus beta-lysin?

Group A streptococci
Group B streptococci
Group C streptococci
Group D streptococci

Group B streptococci

14. Which of the following is acceptable for therapy?

Fluoroquinolones
Penicillin
Cephalosporin
Aminoglycosides

Fluoroquinolones

15. Which of the following agars should be used for culturing Legionella ?

CIN
BCYE
SMAC
XLD

BCYE