Can an infection regress?

Yes you can, the ears, the sinuses, the nose and the throat have common access to each other.

if you do not clean it it will get infected

infection (in-fek-shun) n. 1. Germs that get in your skin when bitten or scratch also. An invasion and multiplication of microorganisms or infectious agents in the body tissues.An infection is a...

It could be but usually is not. Nosocomial simply means that the infection [caused by any type of pathogen, including food-borne germs] was acquired in a health care setting, such as a hospital, lab,...

You cannot get diabetes from contact with someone who has diabetes.