Viral infections generally don't last past a certain amount of time, so when someone who is not immunocompromised clearly has an infection past a certain point, it is assumed to be bacterial.

It's also not unusual for someone to end up with a bacterial infection because their immune system is weakened from the viral infection.

Your coworker almost certainly didn't repeat everything the doctor said or did, nor should she have to; mind your own business. It's wild that you were not there, don't posses any medical training, but consider yourself more qualified...