Tech #890: Novel coatings and topical applications that prevent and eliminate bacterial fungal biofilms

Approximately 65-80% of all bacterial infections in humans are biofilm-related. Microbial biofilms, communities of adherent bacteria or fungi embedded in a matrix of exopolymeric substances (Fig 1), are a significant medical challenge as they are highly resistant to antimicrobial agents, disinfectants, and immune defenses. In fact, biofilm embedded microorganisms can tolerate antibiotic doses up to 1,000 times greater than doses that kill free-floating bacteria. Exopolysaccharides are a major component of the biofilm matrix, where they contribute to biofilm adhesion, architecture, and resistance. Biofilms can form on biotic surfaces, such as lung epithelial cells or other organs, and abiotic surfaces including, medical devices and implants, and they are responsible for biofouling in industrial and commercial settings.

The current standard of care for device associated infections is removal of the infected device plus antibiotic treatments. This is associated with increased health care costs due to recurrent hospitalizations. As such, there is a need for novel strategies to target biofilm formation.

Our scientists have identified novel hydrolase enzymes for degrading and inhibiting production of bacterial and fungal biofilms. These compositions target and degrade the exopolysaccharides produced by several pathogenic species including, but not limited to; Pseudomonas spp, Escherichia coli, coagulase negative Staphylococcus spp, Acinetobacter baumannii, and Aspergillus fumigatus. Dispersing the biofilms increases the efficacy of antimicrobials both in vitro and in vivo (Fig 2).

These enzymes can also be easily coated onto the surfaces of medical devices such as catheters to prevent biofilm formation (Fig 3). In vitro and in vivo proof of concept studies to prove the efficacy of a combination of these enzymes on multispecies biofilms are currently in progress.

Current treatments for infected wounds consist of wound debridement followed by prolonged use of antibiotics to clear the infection. It is well established that this practice can contribute to antibiotic resistance. As such, the topical application of the enzymes to wounds was also evaluated. Preliminary results when the enzymes are included as a topical ingredient in burn wound ointments show that there is no adverse immune response at the site of application. In mouse burn wound models, we have shown that the hydrolases increase the efficacy of antibiotics such as tobramycin (Fig 4). Examination of the efficacy of using these enzymes to improve healing of an infected wound is a proposed next step.

Diverse applications:

• Coatings for medical devices and implants
• Anti-infectives for wounds and lung diseases
• Disinfecting products

Advantages:

• High enzyme specificity reduces likelihood of antimicrobial resistance
• Low quantities of enzyme (nanomolar) can prevent biofilm formation and disperse existing biofilms in less than 1 hour.
• Enzymes synergize with standard antimicrobials and make them more effective.
• Enzymes are easy to produce, stable and non-toxic.
• Enzyme coatings are active and stable for up to 8 days on surfaces.
• High (milligram) quantities of enzymes are non-toxic to human lung fibroblast cells and preliminary toxicity studies in mice are promising.

Extensive in vitro data available; animal studies testing efficacy, toxicity, and PK in bacterial and fungal models of pulmonary infection. Studies are in progress for the following:

Surface derivatized models

• Will evaluate catheter surface coating models under flow for 30 days, to demonstrate robustness of coating overtime.
• Conducting studies to increase breadth of bacterial and fungal protection using a bi-functional enzyme treated model.
• Rat models of catheter infection are in progress.

Wound infection

• Porcine models of burn wound infection are proposed.

The current findings point to a promising avenue for the development of these enzymes as novel therapeutics for the treatment of a wide variety of chronic infections, including pulmonary diseases (cystic fibrosis, invasive aspergillosis, and whooping cough), wound infections which affect 1-2% of the world’s population, and medical device associated infections.