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Health Matters: The war against biofilms

Conway McLean, DPM, Journal columnist

Infectious disease is a hot topic when it comes to medical news, and understandably so. But viral diseases are only one of the reasons it is a subject of intense research and ongoing study. Bacterial infections are also one of those areas of great concern by experts. The day seems ever-closer that a simple scratch routinely leads to a deadly infection. The primary reason: antibiotic resistance.

Depending on many factors, bacteria can be found in many different environments. They may be swimming freely in liquids, or even in human blood if the individual has septicemia (a blood-born infection). There are benefits to those bacteria who are mobile: they can find food or move away from things they do not like, such as bright sunlight or attacking cells from our immune system. But most bacteria function better when stationary, immobile. This method takes less energy and is the first step in the process of biofilm formation.

A biofilm is a collection of one or more types of microorganisms and they can grow on many different surfaces. The microorganisms that are able to form biofilms include many different kinds of bacteria, even many fungi. A biofilm comprises any cooperative collection of microorganisms where the cells stick to each other and, very importantly, also to a surface. And biofilms are present and of significance in up to 80% of all infections in people. They are a tremendous health issue.

These immobile and unmovable communities colonize many surfaces, forming incredibly strong, enduring attachments. It is a well-recognized tendency of many different bacteria to attach to surfaces and form these communal structures. The production of the slimy substance which houses these organisms is a key to the resistance to antibiosis these bacterial communities possess.

The many maladies in some way associated with biofilms are often a consequence of this slimy soup in which they reside. It is called the extracellular matrix, meaning that it surrounds and encompasses these bacteria. This matrix is not part of some artificial intelligence movie universe but a big part of our world. Biofilm provide the resident bugs with a form of superpower; the ability to resist many of our best antibiotics. Some potential surfaces include household and industrial plumbing, biologic materials such as contact lenses, medical implant devices (eg. urinary catheters), as well as animal tissues.

Biofilms provide tremendous protection to the microorganisms from all manner of assault. Not only from acidity, but being starved, along with physical forces. The infections that manifest as biofilm often can only be treated by the physical removal of the film. This leads to greater morbidity and mortality: a higher incidence of pain, problems and death.

Biofilms are typically composed of many different types of organisms, yet their slimy environment allows them to communicate with each other. And even change their genetic structure in response to the presence of the other microbes. This multicellular nature of biofilms provides great resistance to our medications.

Estimates state about 80% of the chronic microbial infections in the human body are due to bacterial biofilm. The bacteria within biofilms have roughly 10-1000 times more resistance to antibiotics than cells which are free-floating. One common example of a biofilm is dental plaque, the slimy buildup of bacteria that forms on the surfaces of teeth. Apparently, consuming sugary treats and drinks causes an increase in the production of acids by the many bacteria found in plaque.

Biofilm-type infections can be broadly divided into two types, with one being those forming on non-biologic surfaces. Some frequently mentioned candidates include medical devices, like joint implants or in-dwelling catheters. The other type is the biofilm infection of a host tissue, as in chronic, non-healing wounds. In wound care, biofilms are frequently encountered, whether their presence is recognized or not. A bloodstream infection can be caused by the biofilm initially formed on medical implants, such as heart valves, joint prostheses, or dental unit. These infections are best treated by removal of the implant, increasing the cost of treatment and morbidity to patients.

As mentioned, physical removal seems the most effective treatment option. Antibiotics are used, of course, but their effectiveness is poor. In a chronic wound, debridement is a necessity, the act of cutting out the biofilm material. When an implant is involved, it is typically removed. This can be problematic, depending on the situation. When the implant is securing a complex fracture, there often is no good solution.

Some new approaches are in development. Nanotechnology seems promising, since these minute molecules have the ability to penetrate the biological barrier that is a biofilm. Another method under investigation employs enzymes, molecules which degrade the biofilm matrix. The formation of biofilms are controlled by signalling genes produced by the bacteria. Various compounds being developed are able to disturb this essential communication process employed by the resident bacteria.

Bacterial biofilms are a serious global health concern due to their ability to tolerate both antibiotics and the host’s defense systems. They lead to billions of dollars in healthcare cost. These strange, hybrid communities can be found almost anywhere and have a tremendous impact on human health, most often negatively. They will continue to have great importance for public health because of their role in infectious disease. Will we learn to crack the puzzle that is bacterial biofilms, to vanquish these resistant invaders? Or will they continue to create a plethora of device-related infections. Only time, and research, will tell.

Editor’s note: Dr. Conway McLean is a physician practicing foot and ankle medicine in the Upper Peninsula, with a move of his Marquette office to the downtown area. McLean has lectured internationally on wound care and surgery, being double board certified in surgery, and also in wound care. He has a sub-specialty in foot-ankle orthotics. Dr. McLean welcomes questions or comments atdrcmclean@outlook.com.

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