The Golden Age of Medical Microbiology

Question 1
What time period is considered the “Golden Age of Medical Microbiology”? Why was it given that name?
The Golden Age of Medical Microbiology was between 1850 and 1915 because scientists were able to prove that microorganisms were the disease-causing agents using the germ theory. As a result, numerous microbial causes of common ailments were identified during this period.

Question 2
Compare and contrast pathogenic bacteria and commensal bacteria.
Pathogenic bacteria cause disease infections in the host organisms, while commensal bacteria derive food and shelter from their hosts without harming the organism.

IncorrectQuestion 3
0 / 0.5 ptswrong
The four bacteria genera covered in this lab are:
, , , and .

Question 4
0.5 / 0.5 pts
enteric _ bacteria live in the gut (intestines) of animals.

IncorrectQuestion 5
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A fastidious __ bacterial species requires enriched media and often specific environmental conditions to grow in culture.

IncorrectQuestion 6
0 / 1 pts wrong
Check all types of media which are selective:

Blood agar (TSA+5% Sheep’s blood)

Chocolate agar (Choc)

CNA blood agar (CNA)

Nutrient agar (NA)

Mitis salivarius agar (MSA)

Mannitol salt agar (MSA)

PartialQuestion 7
0.75 / 1 pts wrong
Check all the enriched media:

Mitis salivarius agar (MSA)

Mannitol salt agar (MSA)

Chocolate agar (Choc)

Blood agar (TSA+5% Sheep’s blood)

Nutrient agar (NA)

IncorrectQuestion 8
0 / 1 pts wrong
Check all the differential media:

Blood agar (TSA+5% Sheep’s blood)

Yeast Peptone Dextrose agar (YPD)

Lowenstein-Jensen Medium

Mitis salivarius agar (MSA)

Brain heart infusion agar (BHIA)

Chocolate agar (Choc)

CNA blood agar (CNA)

Mannitol salt agar (MSA)

PartialQuestion 9
0.33 / 1 pts wrong
Check the media which are both differential and selective:

Mitis salivarius agar (MSA)

Blood agar (TSA+5% Sheep’s blood)

Chocolate agar (Choc)

Mannitol salt agar (MSA)

Colistin Nalidixic Acid blood agar (CNA)

Question 10
1 / 1 pts
Media that is made with extracts from beef, liver, heart, yeast, or any other protein and nutrient source without specifically knowing the exact amount of each nutrient are called , whereas media is made with measured amounts of each specific nutrient.
Answer 1:
undefined
Answer 2:
defined

Question 11
0.5 / 0.5 pts
____ inhibitors______ increase the selectivity of media by reducing the chance of non-target bacterial species to grow.

IncorrectQuestion 12
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Differential media must have one or more _ dyes______ in order to distinguish between the growth of different bacterial species.

Question 13
Contrast cell morphology and colony morphology as a characteristic of bacterial species.
Colony morphology is used to characterize bacteria based on the characteristics of an individual bacterial colony; the variations used are color, texture, shape, and size. Whereas, cell morphology differentiate individual bacterial cells based on how they look under a microscope. Common descriptors include bacillus and cocci.

IncorrectQuestion 14
0 / 1 pts wrong
Whereas the Gram stain technique differentiates between two large groups of bacteria on the basis of the presence of in the cell walls, the acid-fast stain identifies bacteria in the genus based on the presence of in the cell wall.

Question 15
List the steps of the acid-fast staining protocol.

  1. Use the sterile technique to prepare a bacterial smear on a clean slide and let it air dry.
  2. Fix the smear using heat. If sodium hypochlorite has not beed used on the smear, fix it using alcohol and do not stain immediately.
  3. Use carbol fuchsin to conceal the smear.
  4. Apply heat to the stain until vapor rises.
  5. Wash the slide with distilled water
  6. Decolorize the smear with 3% v/v acid alcohol for five minutes. (Should form a pale pink color)
  7. Rinse it with clean water
  8. Use malachite green stain to cover the smear for one to two minutes, depending on the smear’s width.
  9. Clean using distilled water.
  10. Rub the slide’s back until it is clean and air dry it in draining rack
  11. Use a microscope to observe the smear under the x100 oil immersion objective

Question 16
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Streptococcus and Staphylococcus species can be differentiated on the basis of the α-hemolysis__ of red blood cells under the growth of their colonies on blood agar plates.

IncorrectQuestion 17
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The bacterial growth on this blood plate is showing this kind of hemolysis: _____.

Question 18
What are the ingredients in Mitis Salivarius Agar that allow for the differentiation between different Streptococcal species? Please explain.
Trypan Blue and Crystal Violet allow for the differentiation between streptococcal species because they inhibit the growth of most gram-negative and gram-positive microbes. Streptococci absorb Trypan Blue resulting in the development of blue colonies. S. mutans may also be inhibited by the named ingredient’s presence in Mitis Salivarius. Longer incubation may make the identification of S. mitis easier.

Question 19
0.5 / 0.5 pts
Neisseria is a fastidious bacterial genus. A special blood medium called agar, and incubation at 37 degrees Celsius in a jar with elevated carbon dioxide are essential for the cultivation of Neisseria.
Answer 1:
chocolate
Answer 2:
candle

Question 20
How do you distinguish between Staphylococcus aureus, S. epidermidis, and S. saprophyticus? Three tests/growth media apply.

  1. Coagulase test
  2. Mannitol salt agar (MSA tests)
  3. Novobiocin test

Question 21
0.5 / 0.5 pts
What dye in Mannitol Salt Agar (MSA) allows for the identification of mannitol hydrolysis by Staphylococcus aureus?

Question 22
What are two known diseases caused by Mycobacterium species?
Your Answer:
Tuberculosis
Leprosy

IncorrectQuestion 23
0 / 0.5 pts wrong
Which of the Staphylococcus spp. used in the lab is a known nosocomial (hospital-aquired) pathogen?
(Use the correct scientific name – though you may not be able to italicize it. :()

Question 24
Which Neisseria spp. causes an STD? Gonorrhea
Which Neisseria spp. can infect the membranes surrounding the brain and spinal cord? Neisseria meningitidis

Sample Solution

ACED ESSAYS