Gram Stain

1. Why are direct gram stains ordered on clinical specimens?

2. Why is a direct gram stain performed on all anaerobic cultures, even if it is not specifically ordered by the physician?

3. Why is a gram stain performed on all CSFs?

4. List (By gram stain morphology) the three most expected organisms from CSF.

5. Why are gram stains not ordinarily done on a) vaginals and b) stools? Be specific by stating the exact interfering organism(s).

a. Vagina:_______________________________________________________
b. Stool: ________________________________________________________

6. What most likely are the following organisms from direct gram stains?

Sputum g + dc in pairs
Sputum g – cb
Wound g + c in clusters
Wound g + c in chains
Genital g – dc, intracellular

7. What is the purpose of the mordant in the Gram stain procedure?