Deck 5: Specimen Management

Question 1

Which type of media is designed to distinguish microorganisms on the basis of certain growth characteristics?

A) Selective
B) Nutritive
C) Differential
D) Definitive

Answer 1

C
Many different types of media exist and serve many different purposes in clinical microbiology.Some types are differential in that they allow the discrimination of microorganisms on the basis of certain growth characteristics.

Question 2

Which specimen culture, if positive, should be immediately reported to the clinician?

A) Urine
B) Blood
C) Throat
D) Stool

Answer 2

B
A positive blood culture is considered a critical value because of the possibility of bacterial sepsis.Critical values are always immediately reported to the clinician; appropriate antimicrobial treatment should be administered right away.

Question 3

The best anticoagulant to prevent clotting of specimens, such as blood, bone marrow, and synovial fluid, which are submitted for recovery of all types of microorganisms, is:

A) sodium polyanethol sulfonate (SPS).
B) heparin.
C) citrate.
D) ethylenediaminetetraacetic acid (EDTA).

Answer 3

A
SPS is the least inhibitory anticoagulant, which makes it the best choice for preserving blood, bone marrow, and synovial fluid.

Question 4

Specimens for microbiologic studies should be:

A) transported to the laboratory within 48 hours of collection.
B) collected in nonsterile specimen containers.
C) transported in sealable, leak-proof plastic bags with a separate section for paperwork.
D) sent to the laboratory on ice, no matter what type of specimen.

Question 5

Increased concentrations of CO₂ (5% to 10%)and approximately 15% O₂ produce an environmental condition that best suits which type of organism?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles

Question 6

Reduced O₂ (5% to 10%)and increased CO₂ (8% to 10%)produce an environmental condition that best suits which type of organism?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles

Question 7

Colonies of Streptococcus pneumoniae appear alpha-hemolytic on blood agar media.Which one of the following statements explains this discrepancy?

A) The lot of blood agar may be expired.
B) Something may be wrong with the strain of S. pneumoniae since it should be beta-hemolytic on blood agar.
C) Something may be wrong with the strain of S. pneumoniae; it should be gamma-hemolytic on blood agar.
D) No discrepancy is present. S. pneumoniae should be alpha-hemolytic on blood agar.

Question 8

Rejection of inappropriately collected or transported specimens:

A) is the sole responsibility of the laboratory and should be performed without regard to physician requests.
B) should be initiated by laboratory personnel but approved by the nurses or physicians responsible for the care of the patient.
C) is not in the best interest of patient care and should not be considered appropriate.
D) is the responsibility of the nursing staff and should not be an issue for laboratory personnel.

Question 9

The definitive identification of clinically significant isolates is:

A) always necessary and should be carried out by the laboratory at all times.
B) desirable in most cases; however, limited identification may sometimes be necessary and helpful.
C) often not cost effective and should be performed only when requested by the attending physician.
D) not necessary in most cases and should not be routinely performed by the laboratory.

Question 10

An example of a beta-hemolytic gram-positive organism is:

A) Staphylococcus aureus.
B) Streptococcus pneumoniae.
C) Escherichia coli.
D) Enterococcus.

Question 11

Which specimen is quantitatively plated by using a calibrated loop?

A) Stool
B) Sputum
C) Joint fluid
D) Urine

Question 12

Ambient air, which contains 21% oxygen (O₂)and a small amount (0.03%)of carbon dioxide (CO₂), is the environmental condition that best suits which type of organism?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles

Question 13

Holding media, such as Stuart's medium and Amie's transport medium, are used to:

A) maintain the viability of microorganisms present in a specimen.
B) support the growth and multiplication of any pathogenic organisms that are present.
C) prevent clotting of specimens such as blood, bone marrow, and synovial fluid.
D) allow pathogenic organisms to grow while nonpathogenic organisms die.

Question 14

A principal role of the clinical microbiologist includes:

A) quickly and accurately communicating information about the patient in both verbal and written formats.
B) assisting nurses and/or phlebotomists on the floor when drawing blood cultures.
C) diagnosing and treating patients.
D) designing software for microbial databases.

Question 15

Which type of media is designed to support the growth of one group of organisms, but not another, by containing antimicrobials, dyes, or alcohol?

A) Selective
B) Nutritive
C) Differential
D) Definitive

Question 16

Direct examinations such as the Gram stain serve what purpose?

A) To determine the organism's genetic makeup
B) To give the physician an early indication of what may be wrong with the patient
C) To determine the type of flora in the throat and stool specimens
D) To determine the organism's colonial morphologic features

Question 17

An example of a selective medium for gram-positive organisms is:

A) MacConkey agar.
B) blood agar.
C) colistin and nalidixic acid.
D) thioglycollate broth.

Question 18

The appropriate storage for a cerebral spinal fluid specimen is ____° C.

A) 4
B) 22
C) 37
D) -70

Question 19

Which type of media is designed to support the growth of a wide range of microorganisms?

A) Selective
B) Nutritive
C) Differential
D) Definitive

Question 20

Between 5% and 10% hydrogen (H₂), 5% to 10% CO₂, 80% to 90% nitrogen (N₂), and 0% O₂ produce an environmental condition that best suits which type of organism?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles