Can Gram-positive organism appear as Gram-negative?

Answer 1

Staphylococcus are Gram positive because, in Gram's test, the decolorizing agent (ETOH) cannot penetrate the thick cell walls, and the stain remains behind: hence Gram positive. I am not aware of a gram negative staph species and, considering the degree of mutation that would be needed to form such a strain, I do not believe that it's possible. I should add that a not-so-brief scan of the net showed me no Gram negative staph mentioned anywhere. So -- for now -- no. That said, let's see what the future holds.

Answer 2

Yes.Whether it is gram positive or negative all bacteria can be seen by gram stain.Gram positive only mean the purticular colour of bacteria in gram stain(violet) and gram negative organism will be seen as pink.

Answer 3

No, the Gram stain is a differential stain which classifies bacteria as either gram-positive or gram negative.

The cell is first stained with a primary stain such as crystal violet.All bacteria are stained purple by this basic dye. after that a mordant(Grams iodine) is applied. Next a decolorizing agent (ethanol or ethanol-acetone)is applied. The primary stain is washed out(decolorized) of some bacteria(Gram -Neg),whereas others are unaffected(Gram-Pos).A secondary or counterstain such as safranin is applied, this stains the gram- neg bacteria red.

The cells that decolorize easily are gram negative, those that hold the primary stain are gram positive.

Negative staining is used to show better morphology(shape) and size of cells, as well as being used in hard to stain bacteria such as coccobacilli.

Answer 4

Sure, why not.