How does cellulitis start?

Any skin opening. Any skin opening from a bug bite to an injury or scratch can allow bacteria to penetrate into the skin and grow which is cellulitis.
Many Causes. Cellulitis is an inflammation (red, hot swollen and tender) of the skin and soft tissues. It can be cause by many things such as bacteria, sunburn, vein disease and trauma all of which have different treatments. Depending on where it occurs and what is the cause, changes the treatment. If you keep having recurrences, the treatments are wrong, seek another opinion.