Deck 7: Microscopic Examination of Materials From Infected Sites

Question 1

Commonly encountered polymicrobial infections are common in

A) perirectal abscesses.
B) indwelling catheter infections.
C) infant meningitis.
D) food poisoning.

Answer 1

A

Question 2

When a laboratory professional examines a specimen smear, he or she should be looking for all of the following, except

A) squamous epithelial cells.
B) mucus.
C) bacteria without the cells of inflammation.
D) debris.

Answer 2

B

Question 3

All of the following are signs of acute inflammation on a bacterial smear, except

A) mucus.
B) red blood cells.
C) neutrophils.
D) protein background.

Answer 3

A

Question 4

When making slides of thin materials such as urine and cerebrospinal fluid (CSF)

A) spread the material once, let the specimen dry, then spread another layer on top to ensure enough specimen to stain.
B) use the two-slide pull method to ensure evenly distributed material over the slides.
C) dip a swab into the specimen, then roll the swab over the glass slide to ensure adequate coverage for staining.
D) mark the area of the sample drop on the reverse side with a wax pencil and then place a drop of the specimen into the marked area.

Question 5

In the microbiology laboratory, this instrument is routinely used to examine smears for structures that are too small to be seen with the unaided eye.

A) Cytocentrifuge
B) Thermal cycler
C) Compound microscope
D) Electron microscope

Question 6

All the following cells reflect chronic inflammation, except

A) lymphocytes.
B) neutrophils.
C) monocytes.
D) macrophages.

Question 7

Bartlett's method for scoring sputum and the Murray-Washington method for contamination assessment associate what with unacceptable sputum specimens?

A) 10 to 25 neutrophils/10 $\times$ field
B) Greater than 25 neutrophils/10 $\times$ field
C) 10 to 20 squamous epithelial cells/10 $\times$ field
D) Less than 10 squamous epithelial cells/10 $\times$ field

Question 8

A cytocentrifuge is an excellent method for preparing nonviscous fluids, because

A) it deposits cellular elements and microorganisms from the specimen onto the surface of a glass slide as a monolayer.
B) it concentrates the protein evenly throughout the slide surface.
C) the sediment is mixed with 70% albumin before spreading it on the surface of a slide.
D) the cytocentrifuge not only spreads the specimen over the surface of a slide but also stains the specimen.

Question 9

The direct microscopic examination of infected materials, along with specimen site and historical information, may suggest modifications in routine culture techniques to allow the isolation of a suspected pathogen. Common modifications include all of the following, except

A) ordering other culture tests.
B) adding special media.
C) changing incubation temperature or atmosphere.
D) changing the amount of humidity in the incubator.

Question 10

Polymicrobial presentations in smears require more interpretation and must take into account all the following, except

A) smear background.
B) morphology of the organisms.
C) anatomic location of the suspected infection.
D) method used to make the smear.

Question 11

The purpose of a simple stain is to

A) color specific components of specific elements.
B) color the forms and shapes present.
C) specifically identify an organism.
D) identify the types of DNA and RNA present in the nucleus of a cell.

Question 12

Contaminating materials include all the following, except

A) crystallized Gram stain.
B) materials not coming from the collection site.
C) materials not contributed by the inflammatory response from the tissues.
D) materials not likely to contain the infecting organism.

Question 13

The most bothersome contaminating materials for the laboratory professional are those that

A) make it hard to see the pathogenic bacteria through all the mucus.
B) contain microorganisms that will grow in culture and confuse the culture evaluation.
C) make processing the specimen through digestion and straining extremely time consuming.
D) appear to resemble fungus on the direct smear.

Question 14

Why should laboratory professionals look for contamination of a specimen by normal microbial flora?

A) Contaminated specimens will have much amorphous debris that also goes with them.
B) Normal flora always preclude the possibility of a pathogen infecting the area where they reside.
C) The normal flora will be found in clumps, and any pathogenic bacteria will be found with the normal flora.
D) Contamination of specimens with normal flora that are not collected from sterile sites diminishes the value of the culture studies.

Question 15

A bacterial smear may indicate a polymicrobial infection when

A) mucus, red blood cells, neutrophils, and necrosis are on the smear.
B) lymphocytes, monocytes, and macrophages are on the smear.
C) more than one morphologic type of bacteria is present on the smear.
D) both gram-negative rods and gram-positive cocci are present on the smear.

Question 16

When examining specimen smears for pathogenic bacteria, this is important to note.

A) Wright stain reaction
B) Intracellular and extracellular forms
C) Details of the microbe's nuclear structure
D) The amount of fecal material on the slide

Question 17

If a symptomatic patient presents to a physician with an infection, the physician will treat the patient with antibiotics. What role does the laboratory play in antibiotic selection if the physician has already treated the patient before receiving the culture results?

A) The physician has only given the patient antibiotic samples, and they will only last for a couple days-until the culture results are ready and a proper prescription can be written.
B) Physicians will only write antibiotic prescriptions for patients who are infected with a large number of bacteria, so the laboratory needs to tell the physician which antibiotic to use to treat the patient infected with a small number of bacteria.
C) The physician can treat the patient for bacterial infections, but if the patient has a fungal infection, the physician relies on the laboratory to tell her or him if the patient has a fungal infection.
D) The physician expects the laboratory to affirm or reject the antibiotic choice made after the presumptive diagnosis.

Question 18

Because cell wall-damaged bacteria, antibiotic-treated bacteria, or dead bacteria may appear falsely gram-negative, the following are considered "critical cocharacteristics" that assist in the interpretation of the smear include

A) color and cell wall composition.
B) growth characteristics.
C) shape and size.
D) size and color.

Question 19

Culture results

A) confirm the correctness of the therapeutic choices already made and implemented.
B) help the physician select an antibiotic for treatment.
C) must be confirmed before initiating antibiotic treatment for a patient.
D) help confirm the patient's high white blood count.

Question 20

All of the following steps should be used to prepare a smear from thick, granular, or mucoid materials, except:

A) Place a portion of the sample on the labeled slide, and press a second slide onto the sample to flatten or crush the components.
B) Once the material is flattened and sufficiently thinned, pull the glass slides smoothly away from each other to produce two smears.
C) Take an additional swab and rub it back and forth on the two glass slides to ensure the material is thin enough to read once it is stained.
D) If the material is still too thick, repeat the first three steps with another (third) glass slide.

Question 21

What elements should be included in the direct examination of a microbial smear?

A) Only those elements useful in characterizing the specimen
B) Only elements pertaining to the necrosis present in the specimen
C) Only those elements pertaining to the amount of gram-positive cocci present in the specimen
D) Only those elements of contaminating material present in the specimen

Question 22

To assist the physician and the laboratory professional in interpreting sputum smears, all of the following local materials are quantitated, except

A) microbial flora.
B) neutrophils.
C) epithelial cells.
D) mucus.

Question 23

You are working in a microbiology laboratory and receive a sputum for culture. You perform a Gram stain on the sputum and get the following results: 3+ gram-positive cocci, greater than 25 epithelial cells/10 $\times$ field, less than 10 neutrophils/10 $\times$ field, and heavy mucus. What do these results indicate?

A) An acceptable specimen that should be worked up with definitive identification for all bacteria present
B) An unacceptable specimen and workup that should be limited to basic identification of bacteria
C) An unacceptable specimen that should be worked up with definitive identification for all bacteria present
D) An acceptable specimen and workup that should be limited to the basic identification of bacteria

Question 24

Local materials that may be added in the criteria for accepting or rejecting a respiratory specimen include all the following, except

A) mucus.
B) macrophages.
C) bacterial ropes.
D) ciliated columnar cells.