Laboratory Comparison of Hand-Cleansing Agents

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Questions and Answers

What does a rating of '+++' indicate regarding microbial contamination levels?

Little contamination

No contamination

Moderate contamination

A lot of contamination (correct)

When evaluating the effectiveness of a hand-cleansing agent, which aspect should be examined for diversity?

The temperature of the water used

Physical characteristics like color and texture (correct)

The timing of the hand-washing process

The absolute number of microbes only

What might affect the observed effectiveness of various hand-cleansing agents besides the agent itself?

The type of table used during the experiment

Variations in technique among students (correct)

The cleanliness of the lab section

The size of the student's hands

Which of the following interpretations indicates that the cleansing agent was very effective?

Excellent Signup and view all the answers

What aspect of microbial persistence should students consider after washing their hands?

The characteristics of different microbes Signup and view all the answers

What is the purpose of allowing agar plates to cool in an upright position?

To ensure they solidify properly for agar deeps Signup and view all the answers

At what temperature and duration are media typically sterilized in an autoclave?

121 °C for 15 minutes Signup and view all the answers

What happens to brain-heart infusion agar (BHIA) when removed from the autoclave?

It remains liquid until it cools down Signup and view all the answers

How should agar plates be prepared to avoid airborne contamination?

By using sterile Petri dishes and a lid as shield Signup and view all the answers

What is the correct procedure to check for growth in tubes and plates?

Store them at room temperature for 24 hours before examination Signup and view all the answers

What should you avoid doing when transferring organisms with a loop?

Dig into the agar or scoop up a glob of growth Signup and view all the answers

Why is the technique called 'fishtail streak'?

It resembles the movement of a fish's tail in water Signup and view all the answers

What adjustment should be made when transferring a BSL-2 organism?

Make appropriate procedural adjustments Signup and view all the answers

What is the correct order of steps after picking up a sterile agar slant?

Remove the cap, flame the tube's lip, touch the loop to the growth Signup and view all the answers

When handling culture tubes, what should you do after touching the loop to the growth on the agar?

Gently withdraw the loop and make a fishtail motion Signup and view all the answers

What is the primary goal when using a loop for transferring cultures?

To pick up and inoculate the smallest amount visible Signup and view all the answers

What is the recommended procedure for flaming the culture tube?

Flame the culture tube's lip after removing the cap Signup and view all the answers

Which action should be taken immediately after making the fishtail streak?

Flame the loop again to sterilize it Signup and view all the answers

What is crucial to remember when withdrawing the culture tube from the wire?

Keep the loop steady to avoid cutting the agar Signup and view all the answers

What should be done with the culture tube after touching the loop to the growth?

Flame it and replace the cap before putting it down Signup and view all the answers

Study Notes

Hand-Cleansing Agents

Relative growth contamination scale: +++ (a lot), ++ (moderate), + (little), 0 (none).
Emphasize consistency in evaluation despite subjective interpretations of contamination levels.
Observe diversity in microbial growth by noting colors, shapes, textures, and the number of different organisms.

Questions on Effectiveness

Identify which hand-washing agent effectively removed microbes from fingertips.
Determine the least effective agent for microbial removal.
Consider variables influencing differences between individuals’ finger cleanliness.
Recognize any persistent microbes post-washing and explore possible factors causing retention.

Media Preparation and Handling

Weigh ingredients accurately before suspending them in distilled or deionized water.
Heating may be necessary to ensure complete dissolution of media ingredients.
Media sterilization: autoclave at 121 °C for 15 minutes.

Types of Media

Tubed media types: broth, agar slant, agar deep tube.
Agar slants are allowed to solidify at an angle; agar deeps solidify upright.
Agar plates are prepared by pouring sterilized medium into sterile Petri dishes.

Microbial Culture Handling

Proper handling of culture tubes includes flaming and maintaining sterility during transfers.
Utilize a loop to inoculate agar surfaces carefully without damaging the media.
Maintain a sterile environment to avoid contamination during transfers.

Labeling Protocols

Always label sterile media with name, date, medium type, and inoculum source.
Consistent adherence to labeling ensures accurate tracking of cultures and experiments.

Miscellaneous Techniques

Employ "fishtail" streaking technique for loop inoculation on agar, resembling the motion of a fish tail.
Keep hands steady and flaming techniques consistent for ensuring proper sterilization between transfers.

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Description

This quiz evaluates the effectiveness of various hand-cleansing agents that require air-drying. Participants will record observations and interpretations of the results in a structured table format. Engage with the outcomes to analyze which agents perform best under certain conditions.