Gram stain is used primarily as a differential stain for bacteria, although it will also stain most fungi (especially yeasts) and some parasites, including Strongyloides and Trichomonas. The Gram stain procedure is commonly performed on direct smears of clinical specimens and on smears from cultures.
This course will focus on Gram-stained direct smears.
A direct smear from a clinical specimen can be used to:
- Judge the quality of the specimen.
- Provide the clinician with same-day information regarding possible pathogenic organisms, pending results of culture and sensitivity.
- Contribute to selection of culture media, especially with mixed flora.
- Provide internal quality control when direct smear results are compared to culture results.