MICRO LAB 4 - smear prep and gram stain

How many total smear preparations are you going to make in this lab?

4

How many smear preparations from a broth are you going to make in this lab?

2

While most of the Gram stain procedure can be performed on all slides at once, there is one exception. Which part of the Gram stain procedure should be completed one slide at a time?

decolorizing

For which of the following organisms will you be preparing smears this week (Check all that apply)

• E. coli

• B. sub

• S.epi

What magnification will you be using to view your Gram stains?

Oil immersion 1000x

Which items will be passed through the flame at some point during your smear preparation and Gram staining procedures this week (Check all that apply).

• Completely dry smear slides

• Inoculating loop

• Lip of the stock slant tube

• Lip of the stock broth tube

What is the gram reaction and morphology pictured here?  The image contains clusters of purple sphere shaped bacteria.

Gram positive coccus

What is the Gram reaction and morphology pictured here? The image contains clusters of reddish-pink rod-shaped bacteria.

Gram negative bacillus

When conducting a Gram stain, what is the step that occurs right before applying Crystal Violet?

heat fix

Gram staining results

E.coli

• Negative gram reaction

• Bacillus

• 1000x

B.sub

• Positive gram reaction

• Bacillus

• 1000x

S.epi

• Positive gram reaction

• Coccus

• 1000x

What step in most critical when performing a Gram stain

Describe the two most significant differences between smear prep using stock broth vs. using a slant or plate culture

During smear prep, what is the purpose of flaming the loop

during aseptic technique, what is the purpose of flaming the lip of the test tube