because of a hurricane, your regular laboratory session was cancelled and the gram stain procedure was performed on cultures incubated for a longer period of time. Examination of the stain staphylococcus aureus slides revealed a great deal of color variability ranging from intese blue to shades of pink. Account for this result. Solution Staphylococcus aureus is a Gram positive, non motile bacteria. On Gram staining it will appear purple to blue color since it will retain crystal violet dye. Again, Gram negative bacteria say for example, E.coli will appear pink in color. So, here due to longer period of incubation the culture has been contaminated with Gram negative bacteria. Therefore showing color variability in Gram staining results..