Have you witnessed blatant sexism in your workplace and how do you handle it?

My boss is a female doctor in a hospital and some of the male physicians have refused to speak to her, answer her or otherwise pretends she doesn’t exist. She has only been at the facility a month, so I don’t feel it is anything she has done other than be a female. To further confirm our suspicions that she is being discriminated against, a male physician started in our office today and the male physicians in the hospital practically hurdled counters to welcome the man. So how do you handle discrimination other than reporting it to higher ups?