Understanding the causes of chronic infections – when biofilms go bad
Recurrent infections are a common problem in many species, including our dogs. If your dog has had Itchy ears that don’t seem to get better or urinary tract infections that come back over and over again, you (and they!) have probably experienced the frustration of a chronic infection.
In the mid-20th century, physicians began to recognize the emergence of chronic infections, including those caused by bacteria. Scientists began to study the problem more closely in order to determine why some infections are so difficult to eradicate. Researchers discovered that one reason is the formation of biofilms.
Most bacteria tend to grow as a single organism. However, under the right conditions, many types of bacteria and other organisms can aggregate and form a biofilm. Biofilms are “mats” of bacteria and other substances such as fungi and algae. This build-up creates a special, slimy, glue-like substance that binds the group together. This biologic glue helps the bacteria adhere to all kinds of materials, such as body tissues, metal (for example, exam tables), and medical implants. The resulting biofilms are much more resistant to treatment, and appear to be a major cause of chronic infections.
Bacterial biofilms tolerate disinfecting agents and antibiotics, and they’re more resistant to our bodies’ normal immune defenses. However, if the biofilm is broken apart, researchers found that these same bacteria once again become vulnerable to these same antibiotics, disinfectants and immune responses.
The Golden Retriever Lifetime Study is a unique opportunity to investigate many different types of diseases, including acute and chronic infections. For example, so far, 687 study dogs have been diagnosed with ear infections. In people, these types of infections have been linked to biofilm formation.
Not all biofilms are bad. Some biofilms are made up of “good” bacteria and their presence is beneficial, such as in the lining of the intestinal tract and the skin. However, infections due to “bad” biofilm formation increasingly are being recognized in veterinary medicine, although information on this problem in dogs is scant.
Monitoring dogs over long periods of time will help us understand underlying factors that might be contributing to chronic or resistant infections. A greater understanding of the factors that influence biofilm formation will help veterinarians and pet owners develop better strategies to avoid development of biofilms. This is a research area at Morris Animal Foundation that holds interesting promise for the future in preventing and treating chronic infections in our pets.