Deck 8: Clinical Laboratory Procedures

Question 1

For which of the following parasites might the examination of as many as six specimens be needed in order to recover the parasite?

A) Dientamoeba fragilis
B) Entamoeba histolytica
C) Giardia lamblia
D) Strongyloides stercoralis

Answer 1

Giardia lamblia

Question 2

If patients must be purged to enhance recovery of parasites, any of the following enemics may be used EXCEPT:

A) Castor oil
B) Epsom salts
C) Fleet phospho-soda
D) Sodium sulfate

Answer 2

Castor oil

Question 3

The chemical found in fecal preservatives that enhances adhesion of parasites to slides prepared for trichrome stain is:

A) MIF (merthiolate-iodine-formaldehyde)
B) PVA (polyvinyl-alcohol)
C) SAF (sodium acetate-acetic acid-formalin)
D) Schaudinn solution

Answer 3

PVA (polyvinyl-alcohol)

Question 4

When performing an ocular micrometer calibration procedure for the 40x objective, the technologist noted that the 40 mark on the ocular micrometer scale lined up exactly with the 0.09-mm line on the stage micrometer scale. The width in millimeters for each ocular scale division is:

A) 0.09 mm
B) 0.00225 mm
C) 2.25 µm
D) 40 µm

Question 5

Charcot-Leyden crystals are occasionally observed in stool. These crystals are probably from breakdown products of:

A) Eosinophils
B) Lymphocytes
C) Monocytes
D) Neutrophils

Question 6

The most sensitive method used to recover Acanthamoeba spp. from eye-care solutions or corneal samples is the:

A) Giemsa stain
B) Monoclonal antibody method
C) Non-nutrient agar plate seeded with E. coli bacteria
D) Novy-MacNeal-Nicolle (NNN) medium

Question 7

Modified acid-fast stain is used to visualize several parasites including Cryptosporidium parvum. The modification that differentiates this method from that used to stain mycobacteria (AFB) is that in the parasite method:

A) A counterstain is needed
B) The stain is more concentrated
C) The staining time is much longer
D) The decolorizer is weaker

Question 8

Artifacts found in feces that can be confused with eggs or cysts are:

A) Degenerating GI tract-lining cells
B) Dried stain crystals
C) Partially digested meat fibers
D) Pollen grains

Question 9

Artifacts found in feces that can be confused with Entamoeba coli are:

A) Epithelial cells
B) Macrophages
C) White blood cells
D) B or C

Question 10

Artifacts found in feces that can be confused with Strongyloides stercoralis larva are:

A) Dried stain crystals
B) Partially digested meat fibers
C) Plant hairs
D) Vegetable spirals

Question 11

The best method to recover pinworm eggs is the:

A) Acid-fast stain
B) Cellophane tape test
C) Trichrome stain
D) Zinc sulfate flotation method

Question 12

Which of the following eggs is not easily recovered using the zinc sulfate technique?

A) Balantidium coli
B) Flagellates
C) Operculated eggs
D) Taenia spp. eggs

Question 13

When using a trichrome stain to reveal parasites, an amoeba's karyosomes will stain:

A) Dark blue
B) Light blue to green
C) Pink
D) Ruby red

Question 14

Thick blood smears for malaria examinations are "laked" before staining by:

A) Dipping the slide in distilled water
B) Dipping the slide in methanol
C) Leaving the slide in distilled water until all hemoglobin clears
D) Leaving the slide in Giemsa-buffered water for 2 hours

Question 15

If both thick and thin blood smears for malaria examination are negative, the best method to confirm the negative results is a(n):

A) acid-fast stain
B) buffy coat smear
C) fluorescent stain
D) Knott's concentration technique

Question 16

When filariasis is suspected, which of the following will improve the chances to recover parasites?

A) Stain the smear using the modified acid-fast stain
B) Stain the smear using the iron hematoxylin stain
C) Stain the smear using the Giemsa stain
D) Concentrate the sample using the Knott's technique

Question 17

Six Giardia lamblia were seen in a 10-field scanning of a trichrome-stained smear. The correct report of this finding is:

A) None seen
B) Few Giardia lamblia noted
C) Moderate Giardia lamblia noted
D) Many Giardia lamblia noted

Question 18

The technique used to reveal microsporidia in fecal smears is the:

A) Giemsa stain
B) Knott's technique
C) Modified trichrome (Weber and Green)
D) Wheatley trichrome stain

Question 19

Which of the following parasites is autofluorescent?

A) Microsporidia
B) Cyclospora spp.
C) Cryptosporidium parvum
D) Isospora belli

Question 20

All of the following parasites may have diagnostic forms present in sputum EXCEPT:

A) Ascaris spp.
B) Entamoeba gingivalis
C) Paragonimus spp.
D) Trichinella spiralis

Question 21

The modified trichrome stain can be used to reveal microsporidia in a fecal smear. Using this technique, microsporidia will appear as:

A) Black ovals, 6 to 8 µm in diameter
B) Blue ovals, 4 to 6 µm in diameter
C) Pink ovals, 1 to 3 µm in diameter
D) Purple ovals, 8 to 10 µm in diameter

Question 22

When using the agar plate culture method for detecting Strongyloides stercoralis, the positive culture will show:

A) Color change in the medium
B) Larvae growing at the edge of the inoculum
C) Larval tracks made visible by bacterial growth along the track
D) Increased larvae in the inoculum, as shown by washing it with 10% formalin and observing the sediment

Question 23

The appropriate light adjustment when performing a microscopic examination of a wet mount is:

A) Low light
B) Medium light
C) High light
D) Phased light

Question 24

The appropriate specific gravity for a zinc sulfate solution used in the flotation method is:

A) 1.12 to 1.14
B) 1.15 to 1.17
C) 1.18 to 1.20
D) 1.21 to 1.23

Question 25

For which of the following will serology be useful in differentiating acute from long-term infections?

A) Amoebiasis
B) Schistosomiasis
C) Toxoplasmosis
D) Trichinellosis

Question 26

All of the following parasites or their antigens can be detected using immunology procedures EXCEPT:

A) Cryptosporidium parvum
B) Entamoeba histolytica
C) Naegleria fowleri
D) Trichomonas vaginalis

Question 27

Which of the following stains is used to visualize fecal-concentrated smears?

A) D'Antoni stain
B) Giemsa stain
C) Modified acid-fast stain
D) Trichrome stain

Question 28

All of the following fecal preservatives are suitable for acid-fast staining methods EXCEPT:

A) 10% formalin
B) PVA
C) SAF
D) Any of these are suitable

Question 29

The culture medium used to enhance the recovery of Trypanosoma cruzi is:

A) Balamuth medium
B) Cleveland-Collier medium
C) McQuay diphasic charcoal medium
D) Novy-MacNeal-Nicolle (NNN) medium

Question 30

Which of the following parasitic forms is most negatively affected when fecal specimens are stored at room temperature for more than 2 hours?

A) Amoeba trophozoites
B) Giardia lamblia cysts
C) Hookworm eggs
D) Whipworm eggs