Poorly healing wounds may partially be caused by the types of offending organisms they harbor. Tissue is constantly in contact with pathogens which, under the proper conditions, are able to proliferate to create pathological conditions. Many different types of pathogens may be involved.

Poor circulation is another important factor, playing a part in most wounds that do not heal readily. Diabetes provides an example of this, where there can be impaired circulation and altered carbohydrate metabolism. In cases where diabetes affects the peripheral circulation, tissues such as the epidermis and dermis become compromised, and thus are more prone to injuries and persistent infections. Diabetic ulcers frequently develop following simple abrasions, contusions, and lacerations. These ulcers, not unlike decubitus ulcers, are notoriously difficult to treat.

Anaerobic bacteria such as bacteroides, clostridium and streptococci may be active at deeper levels of the dermis, insulated from the healing influence of oxygen. Anaerobic bacteria are responsible for many devastating infections resulting in gangrene. Aerobic bacteria are more closely identified with superficial epidermal layers but may also be involved in infective processes and include staphylococcus epidermis, corynebacteria, propionobacteria.