There are bacteria in every open wound. These bacteria may have originated inside or outside the wound itself. Some of them may have entered the wound from the object that caused the injury. This is also true for animal bites. The first bacteria that enter the wound typically come from the skin of the patient. More often than not, these bacteria do not prevent the wound from healing. However, when the amount of bacteria is greater than the immune system’s ability to heal the wound, an infection can develop.
Slow Healing
Before any classic symptoms of a wound infection appear, it is often noted that the wound does not heal as expected. If the wound hasn't healed in 10 days, it is possibly infected. Bacteria compete for the same components needed for healing and, in some cases, the bacteria consume enough of the material needed by the the healing agents to delay healing.
Heat and Discharge
The wound area might feel hot or feel painful. The area around the wound may appear red and have a distinct foul odor. It is normal for the wound to ooze liquid, but if this becomes thick, greenish or contains pus, an infection has developed. Edema, or an accumulation of fluids beneath the skin, is also common in association with infected wounds. Oftentimes, yellow crust forms over the wound.
Fever and Swelling Lymph Nodes
As the infection progresses, more symptoms appear. The patient may develop a fever and the white blood cell count becomes elevated as the immune system works to fight off the infection. The lymph nodes in the area close to the wound become large and tender as they work to fight the nearby infection. Red streaks under the skin can spread from the wound towards the heart, indicating a spread of the bacteria from the wound.
