Question 1

An organism such as Mycobacterium tuberculosis would absorb which stain in its cell wall?

Accepted Answer

A) Crystal violet 
B) Methylene blue 
C) Carbolfuchsin 
D) Malachite green 
A) Crystal violet 
B) Methylene blue 
C) Carbolfuchsin 
D) Malachite green C

Question 2

Bacterial cells with thick peptidoglycan and numerous teichoic acid cross-linkages are Gram stained.The organisms stain pink.Which one of the following statements explains this discrepancy?

Accepted Answer

A) The bacterial cells were most likely not heat-fixed to the slide. 
B) The bacterial cells were subjected to the decolorizer too long and were overdecolorized. 
C) The lot of Gram-stain reagent is most likely expired. 
D) No discrepancy exists;cells with this composition stain pink on Gram stain. 
A) The bacterial cells were most likely not heat-fixed to the slide. 
B) The bacterial cells were subjected to the decolorizer too long and were overdecolorized. 
C) The lot of Gram-stain reagent is most likely expired. 
D) No discrepancy exists;cells with this composition stain pink on Gram stain. B

Question 3

The first step in the Gram-stain sequence is the application of _______,which is the primary stain.

Accepted Answer

A) safranin 
B) crystal violet 
C) Gram's iodine 
D) Gram's decolorizer 
A) safranin 
B) crystal violet 
C) Gram's iodine 
D) Gram's decolorizer B

Question 4

Magnifications in excess of 100,000 times are achieved by ________ microscopy?

Accepted Answer

A) bright-field 
B) electron 
C) dark-field 
D) phase-contrast 
A) bright-field 
B) electron 
C) dark-field 
D) phase-contrast

Question 5

Gram-positive cocci in clusters were reported on preliminary direct Gram staining from a sputum specimen.The patient was treated with antibiotics.Following 48 hours of treatment,a secondary specimen was reported as gram-positive rods.The discrepancy in this result is:

Accepted Answer

A) the patient likely obtained a secondary infection following treatment of the first pathogen. 
B) the antibiotics are effective and the gram-positive cocci are distorted due to inhibition of growth by the antibiotic. 
C) the first preliminary Gram stain was erroneous,and should have been reported as normal microbiota. 
D) there is no discrepancy. 
A) the patient likely obtained a secondary infection following treatment of the first pathogen. 
B) the antibiotics are effective and the gram-positive cocci are distorted due to inhibition of growth by the antibiotic. 
C) the first preliminary Gram stain was erroneous,and should have been reported as normal microbiota. 
D) there is no discrepancy.

Question 6

When preparing a smear from a viscous and granular sample the microbiologist should:

Accepted Answer

A) add saline to the sample to thin out the specimen for smear preparation. 
B) place some of the material in an enrichment broth and then use the broth for smear preparation. 
C) use a sterile swab and roll it around in the material because it will be easier to roll the sample than to use a loop on the slide. 
D) if the material is not able to be distributed using a sterile loop or swab,use a squash or crush prep to spread out sample. 
A) add saline to the sample to thin out the specimen for smear preparation. 
B) place some of the material in an enrichment broth and then use the broth for smear preparation. 
C) use a sterile swab and roll it around in the material because it will be easier to roll the sample than to use a loop on the slide. 
D) if the material is not able to be distributed using a sterile loop or swab,use a squash or crush prep to spread out sample.

Question 7

When reporting a direct smear from a primary specimen,it is important to note the presence and quantity of white blood cells even in the absence of bacteria for all of the following reasons except:

Accepted Answer

A) the pathogen may not be present in sufficient quantities. 
B) the presence of white blood cells indicates a purulent process. 
C) the pathogen may not be present in the sample collected. 
D) it is not important to report white blood cells unless bacteria are present. 
A) the pathogen may not be present in sufficient quantities. 
B) the presence of white blood cells indicates a purulent process. 
C) the pathogen may not be present in the sample collected. 
D) it is not important to report white blood cells unless bacteria are present.

Question 8

When assessing the quality of a direct Gram stain,neutrophils should appear as:

Accepted Answer

A) cells with pink cytoplasm and darker more purplish nuclear lobes. 
B) cells with pink cytoplasm and pink nuclear lobes. 
C) cells with purple cytoplasm and pink nuclear lobes. 
D) cells with purple cytoplasm and purple nuclear lobes. 
A) cells with pink cytoplasm and darker more purplish nuclear lobes. 
B) cells with pink cytoplasm and pink nuclear lobes. 
C) cells with purple cytoplasm and pink nuclear lobes. 
D) cells with purple cytoplasm and purple nuclear lobes.

Question 9

The value of indirect Gram staining from a broth culture in comparison to a agar plate culture is:

Accepted Answer

A) there is no significant difference in the results of the indirect smear technique. 
B) organisms tend to demonstrate natural cell shape and arrangement in liquid medium. 
C) organisms tend to demonstrate more growth and easier visualization from agar plates. 
D) none of the answers are correct. 
A) there is no significant difference in the results of the indirect smear technique. 
B) organisms tend to demonstrate natural cell shape and arrangement in liquid medium. 
C) organisms tend to demonstrate more growth and easier visualization from agar plates. 
D) none of the answers are correct.

Question 10

In the Kinyoun acid-fast staining method,______ replaces _____ in the primary stain solution.

Accepted Answer

A) increased phenol;heat 
B) heat;increased phenol 
C) mycolic acid;heat 
D) carbolfuchsin;phenol 
A) increased phenol;heat 
B) heat;increased phenol 
C) mycolic acid;heat 
D) carbolfuchsin;phenol

Question 11

After which step in the Gram-stain procedure are gram-positive bacteria first distinguished from gram-negative bacteria?

Accepted Answer

A) Crystal violet 
B) Iodine mordant 
C) Gram's decolorizer 
D) Safranin 
A) Crystal violet 
B) Iodine mordant 
C) Gram's decolorizer 
D) Safranin

Question 12

The fluorochrome stain that can be used to detect mycobacteria is:

Accepted Answer

A) calcofluor white. 
B) acridine orange. 
C) auramine. 
D) immunofluorescence. 
A) calcofluor white. 
B) acridine orange. 
C) auramine. 
D) immunofluorescence.

Question 13

It is important to differentiate white blood cells in a preliminary direct smear because

Accepted Answer

A) the type of white blood cell present definitively indicates whether or not an infection is bacterial. 
B) neutrophils are the only white blood cell present during bacterial infections. 
C) it is not appropriate,because various types of white blood cells are indicative of different bacterial infections. 
D) white blood cells are not noted on preliminary direct smear results. 
A) the type of white blood cell present definitively indicates whether or not an infection is bacterial. 
B) neutrophils are the only white blood cell present during bacterial infections. 
C) it is not appropriate,because various types of white blood cells are indicative of different bacterial infections. 
D) white blood cells are not noted on preliminary direct smear results.

Question 14

When processing a culture swab in the diagnostic laboratory the microbiologist should:

Accepted Answer

A) inoculate the media prior to making the direct smear. 
B) roll the swab back and forth on the slide making sure to transfer organisms. 
C) prepare the smear by rubbing the slide with one side of the swab and utilize the opposite slide to inoculate media. 
D) cancel the direct Gram stain and only set up the media.Request a second swab for the direct smear. 
A) inoculate the media prior to making the direct smear. 
B) roll the swab back and forth on the slide making sure to transfer organisms. 
C) prepare the smear by rubbing the slide with one side of the swab and utilize the opposite slide to inoculate media. 
D) cancel the direct Gram stain and only set up the media.Request a second swab for the direct smear.

Question 15

The limitation associated with utilizing the Gram stain procedure includes all of the following except:

Accepted Answer

A) over decolorizing resulting in all organisms appearing gram negative. 
B) formation of crystals in the stain appearing as gram-positive rods. 
C) providing potential life-saving preliminary organism characteristics. 
D) variable Gram staining characteristics based on organism viability in preparation. 
A) over decolorizing resulting in all organisms appearing gram negative. 
B) formation of crystals in the stain appearing as gram-positive rods. 
C) providing potential life-saving preliminary organism characteristics. 
D) variable Gram staining characteristics based on organism viability in preparation.

Question 16

Which of the following statements is true concerning dark-field microscopy?

Accepted Answer

A) This type of microscopy uses specific stains to enhance the contrast of certain bacteria. 
B) The condenser does not allow light to pass directly through the specimen but directs the light to hit the specimen at an oblique angle. 
C) Dark-field microscopy allows the visualization of larger viruses. 
D) Dark-field microscopy can differentiate various difficult-to-grow organisms by using immunofluorescence. 
A) This type of microscopy uses specific stains to enhance the contrast of certain bacteria. 
B) The condenser does not allow light to pass directly through the specimen but directs the light to hit the specimen at an oblique angle. 
C) Dark-field microscopy allows the visualization of larger viruses. 
D) Dark-field microscopy can differentiate various difficult-to-grow organisms by using immunofluorescence.

Question 17

The most critical step in the Gram stain is the application of the:

Accepted Answer

A) safranin. 
B) crystal violet. 
C) Gram's iodine. 
D) Gram's decolorizer. 
A) safranin. 
B) crystal violet. 
C) Gram's iodine. 
D) Gram's decolorizer.

Question 18

When reporting a direct smear from a primary specimen,it is important to note all of the following except:

Accepted Answer

A) white blood cells. 
B) squamous epithelial cells. 
C) artifacts. 
D) prominent cell shapes and arrangements. 
A) white blood cells. 
B) squamous epithelial cells. 
C) artifacts. 
D) prominent cell shapes and arrangements.

Question 19

In microscopy,resolution can be defined as the:

Accepted Answer

A) magnification power. 
B) extent to which detail in the magnified object is maintained. 
C) ability of objects to stand out from the background. 
D) ability to see objects against a black background. 
A) magnification power. 
B) extent to which detail in the magnified object is maintained. 
C) ability of objects to stand out from the background. 
D) ability to see objects against a black background.

Question 20

The acid-fast stain is specifically designed for bacteria whose cell walls contain:

Accepted Answer

A) teichoic acids. 
B) mycolic acids. 
C) peptidoglycan. 
D) disaccharide-pentapeptide subunits. 
A) teichoic acids. 
B) mycolic acids. 
C) peptidoglycan. 
D) disaccharide-pentapeptide subunits.

Exam 6: Role of Microscopy

An organism such as Mycobacterium tuberculosis would absorb which stain in its cell wall?

Bacterial cells with thick peptidoglycan and numerous teichoic acid cross-linkages are Gram stained.The organisms stain pink.Which one of the following statements explains this discrepancy?

The first step in the Gram-stain sequence is the application of _______,which is the primary stain.

Magnifications in excess of 100,000 times are achieved by ________ microscopy?

Gram-positive cocci in clusters were reported on preliminary direct Gram staining from a sputum specimen.The patient was treated with antibiotics.Following 48 hours of treatment,a secondary specimen was reported as gram-positive rods.The discrepancy in this result is:

When preparing a smear from a viscous and granular sample the microbiologist should:

When reporting a direct smear from a primary specimen,it is important to note the presence and quantity of white blood cells even in the absence of bacteria for all of the following reasons except:

When assessing the quality of a direct Gram stain,neutrophils should appear as:

The value of indirect Gram staining from a broth culture in comparison to a agar plate culture is:

In the Kinyoun acid-fast staining method,______ replaces _____ in the primary stain solution.

After which step in the Gram-stain procedure are gram-positive bacteria first distinguished from gram-negative bacteria?

The fluorochrome stain that can be used to detect mycobacteria is:

It is important to differentiate white blood cells in a preliminary direct smear because

When processing a culture swab in the diagnostic laboratory the microbiologist should:

The limitation associated with utilizing the Gram stain procedure includes all of the following except:

Which of the following statements is true concerning dark-field microscopy?

The most critical step in the Gram stain is the application of the:

When reporting a direct smear from a primary specimen,it is important to note all of the following except:

In microscopy,resolution can be defined as the:

The acid-fast stain is specifically designed for bacteria whose cell walls contain:

Microbial Taxonomy

Bacterial Genetics, metabolism, and Structure

Host-Microorganism Interactions

Laboratory Safety

Specimen Management

Traditional Cultivation and Identification

Nucleic Acid-Based Analytic Methods for Microbial Identification and Characterization

Overview of Immunochemical Methods Used for Organism Detection

Principles of Antimicrobial Action Resistance

Laboratory Methods and Strategies for Antimicrobial Susceptibility Testing

Staphylococcus, Micrococcus, and Similar Organisms

Streptococcus, Enterococcus, and Similar Organisms

Bacillus and Similar Organisms

Listeria Corynebacterium and Similar Organisms

Erysipelothrix, Lactobacillus, and Similar Organisms

Nocardia, Streptomyces, Rhodococcus, Oerskovia, and Similar Organisms

Enterobacteriaceae

Acinetobacter, Stenotrophomonas, and Other Organisms

Pseudomonas, Burkholderia, and Similar Organisms

Achromobacter, Rhizobium, Ochrobactrum, and Similar Organisms

Chryseobacterium, Sphingobacterium, and Similar Organisms

Alcaligenes, Bordetella Nonpertussis, Comamonas, and Similar Organisms

Vibrio, aeromonas, Plesiomonas Shigelloides, and Chromobacterium Violaceum

Sphingomonas Paucimobilis and Similar Organisms

Moraxella

Eikenella Corrodens and Similar Organisms

Pasteurella and Similar Organisms

Actinobacillus, Kingella, Cardiobacterium, Capnocytophaga, and Similar Organisms

Haemophilus

Bartonella and Afipia

Campylobacter, Arcobacter, and Helicobacter

Legionella

Brucella

Bordetella Pertussis and Bordetella Parapertussis

Francisella

Streptobacillus Moniliformis and Spirillum Minus

Neisseria and Moraxella Catarrhalis

Overview and General Considerations

Laboratory Considerations

Mycobacteria

Obligate Intracellular and Non-culturable Bacterial Agents

Cell Walldeficient Bacteria: Mycoplasma and Ureaplasma

The Spirochetes

Overview of the Methods and Strategies in Parasitology

Intestinal Protozoa

Blood and Tissue Protozoa

Protozoa From Other Body Sites

Intestinal Nematodes

Tissue Nematodes

Blood Nematodes

Intestinal Cestodes

Tissue Cestodes

Intestinal Trematodes

Liver and Lung Trematodes

Blood Trematodes

Overview of Fungal Identification Methods and Strategies

Hyaline Molds, Zygomycetes, Dermatophytes, and Opportunistic and Systemic Mycoses

Dematiaceious Molds

Opportunistic Atypical Fungus: Pjirovecii

In the Kinyoun acid-fast staining method,__ replaces _ in the primary stain solution.