Where did the quote "once a nurse always a nurse" originate?

Does anyone know where the quote, "once a nurse, always a nurse" originate? I have heard it and used it often, but I am unable to locate a original source. Thanks!
nope. But it is true. You gain a certain identity and it remains with you from then on.

I don't know where the expression originated, but I do know it's been around a long time. Notice the ways in which it shows itselfin everyday life.I'm disabled, but when we're out in public, we tend to peek into little old ladies carts to check their eating habits, look at vein size of the person ahead of us at checkout, wonder whether thatrambunctious two-year-old is current with his immunizations, people try to show you weird lookng things people should have shown their PC instead.That's the beginning of the story

Ireland.