Exam 1 (MLS) - (CH 6) Specimen Collection and Processing Review Questions

Question 1

Points to Remember

Answer 1

■ The microbiology laboratory must take responsibility for specimen management in the preanalytic laboratory process by ensuring that specimens are appropriately selected, collected, and transported.
■ The collection of specimens for microbiology must include the use of proper technique and containers, adequate quantity, accurate labels, and prompt transportation or provisions to maintain specimen integrity.
■ Shipping of patient specimens or cultures of microorganisms must be performed according to the regulations of the DOT Hazardous Material Regulations.
■ The microbiology laboratory must prioritize the processing of specimens as they are received in the laboratory based on the critical nature of the infection and the potential for specimen deterioration.
■ Performing microbiology analysis on suboptimal specimens provides misleading results. The laboratory must publish guidelines for specimen rejection, and when a specimen is rejected the laboratory must communicate this information to the person, responsible for the patient.
■ Macroscopic observation of the specimen allows the processor to determine the adequacy of the specimen and the need for special processing. A direct microscopic examination is useful in determining the quality of the specimen, detecting the etiologic agent, and alerting the technologist for special procedures.

Question 2

Points to Remember

Answer 2

■ The selection of culture media for each specimen is based on the anatomic site and the organisms likely to be involved in infection at that site. Specimens with fastidious pathogens require enriched media; specimens with an abundance of normal biota require selective media.
■ If several plates are inoculated with a specimen, the media should be arranged in order, beginning with the most enriched medium and progressing to the most selective.
■ The general-purpose isolation streak yields a semiquantitative estimate of growth, whereas the quantitative isolation technique will determine the number of bacteria present in a certain volume of the specimen.
■ Most bacteria cultures are incubated at 35 ° to 37 ° C. The atmosphere will differ depending on the pathogens involved and may involve room air, CO2, microaerophilic, or anaerobic conditions.
■ Microbiology cultures are interpreted using skills to discriminate between normal biota and potential pathogens. The microbiology technologist must have knowledge of which organisms are pathogens in various body sites to perform a clinically relevant workup.
■ The microbiology technologist performs definitive identification using accepted limited identification procedures to maintain cost-effective testing while providing optimal patient care.
■ The microbiology laboratory contributes to effective patient management by communicating accurate and timely results.

Question 3

Basic Principles of Specimen Collection

Answer 3

• If possible, collect the specimen in the acute phase of the infection and before antibiotics are administered.
• Select the correct anatomic site for collection of the specimen.
• Collect the specimen using the proper technique and supplies with minimal contamination from normal biota (normal flora).
• Collect the appropriate quantity of specimen.
• Package the specimen in a container or transport medium designed to maintain the viability of the organisms and avoid hazards that result from leakage.
• Label the specimen accurately with the specific anatomic site and the patient information— patient’s name and a unique identification number, as well as date and time of collection.
• Transport the specimen to the laboratory promptly or make provisions to store the specimen in an environment that will not degrade the suspected organism( s). * Notify the laboratory in advance if unusual pathogens or agents of bioterrorism are suspected.

Question 4

Which one of the following involves specimen management in the preanalytic process?

a. Selecting the appropriate medium for culture
b. Performing a direct microscopic examination
c. Rejecting suboptimal specimens
d. Communicating the results of the specimen culture

Answer 4

c. Rejecting suboptimal specimens

Question 5

A patient has a subcutaneous infection, and the specimen is submitted on a swab. Explain why this is an unacceptable collection method. How should the sample be collected?

Answer 5

Subcutaneous infections are below the external surface of the skin, into the connective tissues. A swab specimen will collect material only from the external cutaneous surface and will not be representative of the infectious process. The sample should be collected via needle aspiration.

Question 6

Which of the following anticoagulants is appropriate for use in microbiology?

a. Citrate dextrose
b. EDTA
c. SPS
d. Sodium citrate

Answer 6

c. SPS

Question 7

Which of the following specimens should not be refrigerated?

a. Urine
b. Urogenital swab
c. Throat swab
d. Sputum

Answer 7

b. Urogenital swab

Question 8

Which of the following specimens requires immediate processing when received in the microbiology laboratory?

a. Urine
b. Cerebrospinal fluid
c. Sputum
d. Stool

Answer 8

b. Cerebrospinal fluid

Question 9

Which of the following are reasons to reject a specimen for culture?
a. The specimen is preserved in formalin.
b. Information on the requisition does not match information on the specimen label.
c. A second stool sample is submitted from the same patient on the same day.
d. All of the above.

Answer 9

d. All of the above.

Question 10

Which one of the following is noted from a macroscopic observation?
a. WBCs
b. Tapeworm proglottids
c. Epithelial cells
d. Protozoan cysts

Answer 10

b. Tapeworm proglottids

Question 11

Chocolate agar is an example of which of the following?
a. Nonselective media
b. Selective media
c. Differential media
d. Enriched media

Answer 11

d. Enriched media

Question 12

Which of the following is an example of a selective and differential medium?
a. Blood agar
b. Chocolate agar
c. MacConkey agar
d. Modified Thayer-Martin agar

Answer 12

c. MacConkey agar

Question 13

Which of the following specimens is cultured using a quantitative isolation technique?
a. Urine
b. Sputum
c. Blood
d. Stool

Answer 13

a. Urine

Question 14

Cultures of Bordetella pertussis are incubated in ambient air at 35 ° C for 6 to 7 days. True or false?

Answer 14

True

Question 15

Compose a list of questions that the microbiology technologist uses when doing a workup of a culture.

Answer 15

• What is the specimen source?
• Does this source have normal flora or is it a sterile source?
• If normal flora is present, what bacteria are found, and what do these colonies look like? * What are the most likely pathogens in this specimen?
• What is the colonial morphology of these pathogens?
• Which medium is demonstrating growth, and what is the purpose of the medium?

Question 16

The microbiology laboratory receives a vascular catheter tip for culture. How should this specimen be processed?

Answer 16

Many laboratories use the Maki roll technique to culture a vascular catheter tip. A segment of the catheter tip is rolled across the surface of a blood agar plate. The plate is incubated, and testing is performed on each organism that produces 15 or more colonies.

Question 17

What is the role of the microbiology laboratory in the postanalytic process?

Answer 17

The role of the microbiology laboratory in the postanalytic process is to communicate accurate and timely information. Preliminary results are often reported as the information becomes available. The laboratory report must be clear and understandable; interpretive statements may be necessary. Critical values must be reported to the physician immediately.