Interestingly enough, the human body has a larger number of germs than it does actual human cells. This is a useful bit of trivia that can help us understand the microbiology of a wound. When skin is broken, germs that normally reside on the surface of the skin go into the wound and start to grow. A wound is a perfect environment for germs, for it is warm, moist, rich in nutrition provided by the dead tissue, and safe from the body’s immune system. No wound open more than 48 hours is sterile. So, do not try to keep a wound sterile; until a wound heals completely, it will always have some germs.
Germs fight hard to keep their newly found territory, the wound. To do so, they produce different chemicals to keep the wound open as long as possible. Some of these chemicals directly break healing tissue. Others inhibit wound healing by blocking chemicals produced by the wound tissue, chemicals which are necessary to recruit new blood vessels and create builder cells – fibroblasts — at the wound site.
When the germs are small in number, wounds can still heal because our soldier white blood cells — “neutrophils” — can kill those germs as needed. But when the germs outnumber our white blood cells, they can overwhelm the wound causing pain and making healing impossible. This is called “critical colonization.”
Finally, wound infection occurs when germs penetrate the tissue from the wound bed, overcoming all the body’s defenses.