Biofilms formed by bacteria that stick to each other on living tissue and medical instruments in hospitals, which make them harder to remove, can be tricked into dispersing with the targeted application of nanoparticles and heat, researchers have found.
The University of New South Wales (UNSW) study, jointly led by Cyrille Boyer, PhD, associate professor in the School of Chemical Engineering and deputy director of the Australian Centre for NanoMedicine, appears in Scientific Reports.
“Chronic biofilm-based infections are often extremely resistant to antibiotics and many other conventional antimicrobial agents, and have a high capacity to evade the body’s immune system,” said Boyer. “Our study points to a pathway for the nontoxic dispersal of biofilms in infected tissue, while also greatly improving the effect of antibiotic therapies.”
Biofilms have been linked to 80 percent of infections forming on living tissues or dwelling in medical devices.
The formation of biofilms is a growing and costly problem in hospitals, creating infections that are more difficult to treat. They also cause fouling and corrosion of wet surfaces and the clogging of filtration membranes in sensitive equipment.
In general, bacteria have two life forms during growth and proliferation: planktonic, where bacteria exist as single, independent cells, or aggregated together in colonies as biofilms, where bacteria grow in a slime-like polymer matrix that protects them from the environment around them.
Acute infections mostly involve planktonic bacteria, which are usually treatable with antibiotics. However, when bacteria have had enough time to form a biofilm, an infection can often become untreatable and develop into a chronic state.
The discovery of how to dislodge biofilms by the UNSW team was made using the opportunistic human pathogen Pseudomonas aeruginosa. This is a model organism whose response to the technique the researchers believe will apply to most other bacteria.
When biofilms want to colonize a new site, they disperse into individual cells, reducing the protective action of the biofilm. It is this process the UNSW team sought to trigger, making the bacteria again susceptible to antimicrobial agents.
The UNSW team found that by injecting iron oxide nanoparticles into the biofilms and using an applied magnetic field to heat them-which induces local hyperthermia through raising the temperature by 5°C or more-the biofilms were triggered into dispersing.
“Once dispersed, the bacteria are easier to deal with, creating the potential to remove recalcitrant, antimicrobial-tolerant biofilm infections,” said Boyer.
This article was adapted from information provided by UNSW.