The largest organ by weight in the body is the skin. Damage to our skin occurs every day. Small cuts, pimples, bruises all come and go without our needing to pay much attention to the wonderful process the body uses to put things back to normal. On occasion these processes are inadequate because of the magnitude of the wound, underlying illness or infection. Some wounds heal partially and then seem to stall out and remain open for long periods. In this setting it may be necessary to work with a wound care expert to aid the healing process. In many cases, the stalled wound is complicated by the presence of a biofilm.

In 1890, the German microbiologist Robert Koch proposed a way to determine which bacteria were causing various diseases. He suggested four conditions. 1. The bacteria must be present in every case of the disease. 2. The bacteria must be isolated from the host with the disease and grown in pure culture. 3. The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host. 4. The bacteria must be recoverable from the experimentally infected host. This was extremely helpful at the time, but as with many scientific advances, it has been proven to be too simple as we understand more. It has been found that many bacteria grow much more effectively when they are in a mixed culture with other bacteria. Each supplies growth factors the other benefits from. Multiple types of bacteria form a mutually beneficial colony which supports one another. Some of these bacteria don’t normally grow in the lab and aren’t considered pathogens (harm causing) in humans, but they are supportive of the other bacteria present. These communities of bacteria can slow or prevent healing in wounds. Such a community of bacteria forms a “biofilm”. The human analogy is the advantage of a town, where one person is the baker, another is a butcher, and another fixes cars. All members of the community specialize and as a result all members benefit. In the case of a biofilm, the bacteria benefit, but the patient suffers.

Biofilm research has opened understanding of why some wounds seem to stay infected and are very slow to improve. A biofilm is a collection of bacteria, proteins, polysaccharides, and DNA which form a sort of adherent goo on the surface of the wound. The bacteria are protected from antibiotics by being physically separated from them by the goo. In addition, some of the bacteria are in a non-growing or dormant phase, which antibiotics don’t attack. The bacteria are even difficult to culture because they do not actively grow when a sample is taken for the lab to culture. Some bacteria produce enzymes which breakdown proteins which are made by the wound cells to help with healing.

Wounds which stall in their healing due to biofilms have to be “jumpstarted “in some way. This often requires physical debridement of the biofilm with surgical excision. In other cases a cleansing solution such as very dilute hypochlorite (bleach) is used. Silver dressing have also been used, but tend to have a very short zone of activity and so don’t penetrate deeply enough into the biofilm to be effective. Once the biofilm has been removed, the wound healing will accelerate. Use of specialized dressing and treatments can then promote a healthy wound environment to protect the wound from reinfection and aid rapid healing.

Questions or comments can be addressed to Frederick M. Ilgenfritz, MD, FACS, c/o Bitterroot General & Vascular Surgery, Wound Management Services, 1150 Westwood Drive, Suite C, Hamilton, MT 59840 or visit www.bgvs.us.