Question

Are there any tips and tricks for gram staining? We are trying to determine if the organism is a staph, strep, enterobacteriaceae and non-fermenters. Apparently, Yersinia has bipolar staining. Can someone help, please.

Answer 1

GRAM STAINING:-
-Heat fixed smear is stain with crystal violet.
Crystal violet stain both Gram- and Gram+ so it is called primay stain.
- Add Gram's iodine. It will adhere only gram+ because of peptidoglycan in their cell wall.
- wash with acetone for about 30 second.
               - Gram- purple dye washed away.             
               - Gram+:- purple dye remain adherent.               - lastly add safranin which will stain cells pink.             

Interpretation:-
(a) Gram positive will appear purple- colour of crystal violet.
(b) Gram negative will appear pink- color of safranin.

Examples:-
1. Staphylococcus-gram-positive aerobic bacteria
2. Streptococcus-gram positive, aerobic bacteria
3. Enterobacterisceae:- gram negative, anaerobic
4. Yersinia:- Bipolar staining is typically described as characteristic of Yersinia pestis;