Deck 7: Microscopic Examination of Infected Materials

Question 1

What is the most common causative agent of gas gangrene?

A) Staphylococcus aureus
B) Neisseria gonorrhea
C) Clostridium perfringens
D) Haemophilus influenzae

Answer 1

C
Several common organisms are encountered in the microbiology laboratory.Infections caused by common single species,or by classic infectious agents,include Streptococcus pneumoniae pneumonia,Sta.aureus abscesses or pyodermas,H.influenzae tracheobronchitis or meningitis in infants,C.perfringens gas gangrene,Nocardia spp.lung abscesses,and gonococcal urethritis.

Question 2

What is the most common causative agent of urethritis?

A) Staphylococcus aureus
B) Neisseria gonorrhea
C) Clostridium perfringens
D) Haemophilus influenzae

Answer 2

B
Several common organisms are encountered in the microbiology laboratory.Infections caused by common single species,or by classic infectious agents,include Streptococcus pneumoniae pneumonia,Sta.aureus abscesses or pyodermas,H.influenzae tracheobronchitis or meningitis in infants,C.perfringens gas gangrene,Nocardia spp.lung abscesses,and gonococcal urethritis.

Question 3

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, then place a drop of the specimen into the marked area.

Answer 3

D
Thin materials such as urine and CSF are difficult to view on a glass slide.Marking the underneath area with a wax pencil will allow the tech to know exactly where the sample was placed.This may be helpful after staining the specimen.Never spread two layers of a specimen on a slide.A drop on a slide contains enough material to be stained and visualized.The two-slide pull method is for thick specimens,not thin.Never use a swab to apply a specimen when there is enough fluid to be dropped onto a slide.

Question 4

A patient comes to the emergency department with a productive cough,shortness of breath,and a fever of 102° F.The patient is diagnosed with pneumonia.What organism commonly encountered in the microbiology laboratory can cause this disease?

A) Streptococcus pneumoniae
B) Staphylococcus aureus
C) Escherichia coli
D) Haemophilus influenzae

Question 5

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

Question 6

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 7

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

A) Wright's 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 8

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

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

Question 9

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 10

What is the most common causative agent of pyoderma?

A) Staphylococcus aureus
B) Neisseria gonorrhea
C) Clostridium perfringens
D) Haemophilus influenzae

Question 11

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 12

Because cell wall-damaged bacteria,antibiotic-treated bacteria,or dead bacteria may appear falsely gram-negative,what are "critical cocharacteristics"?

A) Color and cell wall composition
B) Growth characteristics
C) Shape and size
D) Size and color

Question 13

Commonly encountered polymicrobial infections are:

A) Perirectal abscesses
B) Indwelling catheter infections
C) Infant meningitis
D) Food poisoning

Question 14

A tech is working the night shift and receives a CSF specimen on an infant.The tech makes a Gram stain of the spinal fluid then reads the smear under the microscope.The report the tech sends to the physician reads as follows: "gram-negative bacillus,small and pleomorphic." What bacteria are being implied as the infecting agent?

A) Escherichia coli
B) Legionella pneumophila
C) Staphylococcus aureus
D) Haemophilus influenzae

Question 15

Why should the laboratory professional look for unexpected structures in smears?

A) Large granules, grains, or fungal forms, such as spherules or fungal mats, can best be recognized at low power and give the tech and the physician an insight to the infectious process occurring at that site.
B) Small numbers of organisms in samples from sterile sites must be seriously considered.
C) The inflammatory cells that do migrate into the area of the infection can be lysed, and patients with leukopenia may also have fewer inflammatory cells within their inflammatory debris.
D) Debris is characteristic of particular organisms.

Question 16

A specimen that is spread on a smear and appears to have a homogenous constitution is said to:

A) Be clumped at different areas on the slide
B) Contain pathogens only in one visual field
C) Have material spread evenly throughout the slide
D) Contain normal florae

Question 17

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 18

When using a swab to make a smear:

A) It is okay to use the swab after it has been used to inoculate culture media.
B) Ensure the swab has not been used to inoculate culture media first.
C) Rub the swab back and forth on the glass slide to smear the specimen for easier viewing.
D) Dip the swab in thioglycollate broth for easier smearing on the slide.

Question 19

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 20

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 21

By looking at a bacterial smear,how can you tell if the infection is polymicrobial?

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 22

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 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 23

To assist the physician and the laboratory professional in interpreting sputum smears,all of the following local material are quantitated EXCEPT:

A) Microbial florae
B) Neutrophils
C) Epithelial cells
D) Mucus

Question 24

Some pathogens will not grow in culture and are usually unsuspected.This pathogen can be seen in the sputum and bronchoalveolar fluid of patients with a hyperinfestation syndrome.The name of this pathogen is:

A) Strongyloides stercoralis
B) Giardia lamblia
C) Staphylococcus aureus
D) Klebsiella pneumoniae

Question 25

Pathogens that will grow in culture,but not in routine bacterial culture,can be recognized on the smear and include all the following EXCEPT:

A) Legionella spp.
B) Mycobacterium spp.
C) Bartonella spp.
D) Klebsiella spp.

Question 26

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

Question 27

All the following cells reflect chronic inflammation EXCEPT:

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

Question 28

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 29

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× field,less than 10 neutrophils/10× 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 30

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 31

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 32

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 33

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

Question 34

Barlett'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× field
B) Greater than 25 neutrophils/10× field
C) 10 to 20 squamous epithelial cells/10× field
D) Less than 10 squamous epithelial cells/10× field