Biofilms

Author(s):
Randall D. Wolcott, MD Founder and President

Southwest Regional Wound Care Center
Lubbock, Texas

Published:
October 3, 2014

Abstract

Microorganisms have the ability to live in two forms: planktonic (free-floating) and biofilm (attached or sessile). Most medical information from the hospital laboratory deals with planktonic organisms and relates to Koch's postulates and the corresponding germ theory: one organism, one disease. However, the preferred method of microbial life, based on survival and community diversity, is the multispecies biofilm or sessile community of organisms. In fact, studies now indicate that organism survival 3.4 billion years ago was based on biofilm architecture. Historically, diseases recognized as being associated with biofilms are consistent with chronic infections such as: (1) otitis media, (2) periodontitis, (3) native valve endocarditis, (4) cystic fibrosis, (5) indwelling medical device infections, and (6) prostatitis. Today, that list has expanded considerably, emphasizing the oral-systemic link and chronic wounds. Each of the diverse niches and tissues of the human body can suffer a biofilm infection which manifests as a chronic infection clinically. Enhanced pathogenicity related to biofilms and their recalcitrant nature is associated with their chemophysical properties, acting as hydrated polymers and demonstrating properties of both liquids and solids. Biofilms also possess well-defined molecular mechanisms to produce and maintain chronic infections. Individual species are selected for in specific host environments yet any microorganism alone and/or in synergy with other microbes (even commensals) growing as a biofilm can produce infection. Biofilm infection occurs when a microbe attaches to a host surface, up-regulates up to 800 new genes producing a distinct new biofilm phenotype of the microbe and then self-secretes a polymer matrix while also incorporating fibrin and other host proteins in its protective cover. The way biofilm feeds itself is to inflame the tissues to which it is attached and extract nutrients from the plasma that percolates through its substance.

When microorganisms are up-regulated to the biofilm phenotype, there is significant negative impact on the laboratory capacity to recover the organisms, predict antibiotic susceptibility, and even provide meaningful clinical information for management of patient infection. Further, the majority of inhabitants of a biofilm are viable but nonculturable, necessitating nonculture DNA-based techniques such as polymerase chain reaction, sequencing, and other molecular methods.

Cohabitants of a biofilm have at least 100- to 1,000-fold increase in the ability to resist antibiotic treatment and are not cleared by normal host defenses. Biofilms exchange genetic factors more efficiently and possess multiple colony defenses. Biofilms may be monospecies or multispecies, composed of eukaryote (fungus and yeast), and/or prokaryote organisms with multiple mechanisms to encourage genetic diversity, a key survival strategy. A biofilm infection when combined into one disease entity is more costly and deadly than all cancers combined. For example ventilator acquired pneumonia (67,000), chronic obstructive pulmonary disease (50,000), wounds (50,000), and all other chronic infections kill approximately 500,000 people per year. Most biofilm disease is managed by removing or replacing body parts (legs, heart valves, lungs, etc.), which should stop once we can truly understand and manage biofilm disease.