Biofilms

Biofilms

-Microbial communities - strongly adhered to a surface - submerged in a liquid -surrounded by exopolymeric substance (EPS) - able to communicate within the community by quorum sensing

Urinary Catheter biofilms

-10% to 50% of patients undergoing short term urinary catheterization but virtually all patients undergoing long-term --catheterization (> 28 days) become infected. -Bacteria may ascend the inner lumen into the patient's bladder in 1 to 3 days -pH changes caused by the bacteria cause minerals to precipate from the urine blocking the catheter.

Central Venous Catheter biofilms

-Duration of catheter placement only affects where the highest density biofilm exists -# of organisms on the tip of the catheter is correlated with rate of infection

Biofilms and disease

biofilm illnesses may not respond to antibiotics and may be culture negative biofilm formation in native tissue is a relatively new concept

quorum sensing

communication between bacterial cells using chemcial signals; these signals carry accurate messages to members of the same species, and possibly to some higher organisms; these signals are also one of the ways gene regulation are altered.

Biofilm cultures

composed of planktonic or sessile bacteria

gene regulation

genes in biofilms are regulated differently than in planktonic cell genomes; as a result different metabolic states and different surface proteins among other changes.

Biofilm Growth

growth of one or many species of gram positive and gram negative begins bacteria begins to secrete EPS growth continues creating a 3D matrix featuring channels through which liquids, products, sensory molecules and wastes can flow as well as peaks from which dispersal will occur.

Biofilm Adherence

initial adherence is through impermanent bonds permanent adherence of the initial colonizing species through the use of pili

Disease associated with medical devices

medical biofilms may be single or multi species, G+,G-, yeast or any combination these organisms originate from skin, non-sterile water and other environmental sources.

Examples of diseases exacerbated by biofilms

periodontitis tonsilitis cystic fibrosis otitis media osteomyelitis uti's

Biofilms include

shower scum, toilet scum, tooth scum, lake slime, other slime

Biofilm dispersal

single organisms or larger sections of the pedestals may break off and be transported by the fluid around the biofilm. This facilitates further colonization by the film Enzymes degrade the EPS matrix surrounding the cells may aid in dispersal.

Benefits of bacteria in biofilms

-lower layers of bacteria are physically protected from antimicrobial agents and phagocytosis. -some bacteria within the population slow down metabolic activity -Even if large portions of the biofilm are removed, the tightly adhered base layer is seldom destroyed and can regrow.

Benefits of biofilms

-microbes are critical to global ecosystems - bacteria are naturally found in biofilm populations - biofilms are therefore responsible for most of the processes conducted by bacteria

Mechanical Heart Valve Biofilms

Organisms here come from the skin, other indwelling devices, dental work biofilms colonize the stitches, cuff attachment and local tissue antibiotics alone will generally not cure a patient, regardless of time administration

Communication

bacteria in biofilms communicate via quorum sensing

Industrial benefits

Wasterwater treatment- biofilms on sand filter substrates are used to remove carbon from wastewater Bioremediation- toxic organic contaminants will be removed by the native soil bacteri Mining- microbial leaching