MCB 101 Lab - PART UNO

MCB 101 Lab - PART UNO

Assessment

Flashcard

Biology

University

Hard

Created by

Liza Jane Yoon

Used 3+ times

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16 questions

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1.

FLASHCARD QUESTION

Front

MCB 101 Lab LE Coverage

Back

  1. Lab Ex2 - Antimicrobial Susceptibility Assays

  2. Lab Ex3 - Collection, Identification, and Culture of Fungi

2.

FLASHCARD QUESTION

Front

Bacteria:

Learning Outcomes

Back

1.Prepare standardized inoculum

2.Practice serial dilution and spread plate methods

3.Perform basic assays to test antimicrobial activity

3.

FLASHCARD QUESTION

Front

Define McFarland Standards

Back

-chemical solution of BaCl2 and H2SO4, whose reaction produces a fine precipitate = Barium Sulfate

-when shaken well, its turbidity is visually comparable to a bacterial suspension of known concentration

-used to standardize the number of bacteria in a liquid suspension by comparing the turbidity of the test suspension with that of McFarland standard

4.

FLASHCARD QUESTION

Front

most commonly used standard in clinical microbiology which is prescribed for antimicrobial susceptibility testing and culture media performance testing

Back

0.5 McFarland Standard

0.05 1%BaCl2

9.95 1%H2SO4

1.5 x 10^8 approx. bacterial suspension

5.

FLASHCARD QUESTION

Front

How to prepare inoculum using McFarland Standards?

PROCEDURE

Back

  1. 1. Mix the standard on a vortex or manually swirl/mix prior to examination.

  2. 2. Make sure it is aliquoted into a tube that is the same size and diameter as the tube used to prepare the test suspension.

  3. 3. Prepare a test suspension (obtain fresh pure culture of test org and inoculate in a suitable broth)

  4. 4. Visually compare the turbidity by comparing the clarity of the lines on the Wickerham card in good lighting.

  5. 5. If test suspension is too light, inoculate with additional organisms or incubate tube until turbidity matches that of standard.

  6. 6. If dilution is needed, use sterile pipette and add sufficient broth or saline to obtain matched turbidity.

6.

FLASHCARD QUESTION

Front

why same size and diameter for both standard and test suspension?

Back

for accuracy and consistency

-if diameters differ, depth of liquid in tubes also differ

optical consistency (the way light passes through a liquid can be affected by tube's diameter and shape0

-avoid systematic errors during standardization

7.

FLASHCARD QUESTION

Front

McFarland Standard Precations

Back

1.Sensitive to air and light so tubes should be closed tightly and kept in dark

2.level of standards should be checked occasionally to ensure that evaporation has not occurred.

  1. 3.should be vigorously agitated on a mechanical vortex before each use and inspected for a uniform turbid appearance. If large particles appear or if clumping is apparent discard the standard

  2. 4.Actual numbers of viable bacteria present in an adjusted suspension depends on the size, viability, and clumping of the particular bacterium used

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