[Histonet] B&B Gram negative color change

[Woodward, Denise]

Hello all,

We recently noticed that our B&B positive controls change color over
time after staining. It happens in as little time as a week.
The Gram negative organisms change hue from a nice pink/red to a purple
color. The Gram positive organisms remain blue.
Anyone have any clues as to why/how this is happening?
Sorry to ask a difficult question on a Friday but this one has been
bothering me for a few days.
Thanks,
Denise Long Woodward
UConn
Dept. of Pathobiology and Veterinary Sciences
Storrs, CT