Biofilms -- formed by bacteria that stick to each other on living tissue and medical instruments, making 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 study, jointly led by associate professor Cyrille Boyer of the School of Chemical Engineering and deputy director of Australian Centre for NanoMedicine, appears in today's issue of Nature's open access journal Scientific Reports.
Cyrille Boyer in his University of New South Wales lab. Courtesy of UNSW
Biofilms -- formed by bacteria that stick to each other on living tissue and medical instruments, making 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 study, jointly led by associate professor Cyrille Boyer of the School of Chemical Engineering and deputy director of Australian Centre for NanoMedicine, appears in today's issue of Nature's open access journal 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," says Boyer. "Our study points to a pathway for the non-toxic 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 (e.g., respiratory, gastrointestinal and urinary tracts, oral cavities, eyes, ears, wounds, heart and cervix) or dwelling in medical devices (e.g., dialysis catheters, prosthetic implants and contact lenses).
The formation of biofilms is a growing and costly problem in hospitals, creating infections that are more difficult to treat -- leading to chronic inflammation, impaired wound healing, rapidly acquired antibiotic resistance and the spread of infectious embolisms in the bloodstream.
They also cause fouling and corrosion of wet surfaces, and the clogging of filtration membranes in sensitive equipment -- even posing a threat to public health by acting as reservoirs of pathogens in distribution systems for drinking water.
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 -- within a human host or non-living material such as dialysis catheters -- an infection can often become untreatable and develop into a chronic state.
Although biofilms were first recognised in the 17th century, their importance was not realised until the 1990s, when it became clear that microbes exist in nature more often in colonies made up of lots of different microorganisms that adhere to surfaces through slime excreted by their inhabitants. Thus began a global race to understand biofilms, at a time when it was also realised they were responsible for the majority of chronic infections.
The discovery of how to dislodge biofilms by the UNSW team -- jointly led by Dr Nicolas Barraud, formerly of UNSW and now at France's Institut Pasteur -- 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 colonise 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.
They achieved this using iron oxide nanoparticles coated with polymers that help stabilise and maintain the nanoparticles in a dispersed state, making them an ideal non-toxic tool for treating biofilm infections.
"The use of these polymer-coated iron oxide nanoparticles to disperse biofilms may have broad applications across a range of clinical and industrial settings," says Boyer, who in October was named Physical Scientist of the Year in Australia's Prime Minister's Prizes for Science. "Once dispersed, the bacteria are easier to deal with - creating the potential to remove recalcitrant, antimicrobial-tolerant biofilm infections."
Others involved in the study were Dr. Thuy-Khanh Nguyen and Ramona Selvanayagam of the Centre for Advanced Macromolecular Design and the Australian Centre for NanoMedicine at UNSW; and Dr. Hien T. T. Duong, formerly at the UNSW and now at the University of Sydney.
Source: University of New South Wales
An Infection Preventionist Considers Why Manufacturers Need to Update IFUs
July 11th 2024Katharine J. Hoffman, MPH, CIC, LSSGB: It’s time to take the devil out of the details in interpreting and successfully following manufacturers' instructions for use; why do manufacturers need to update IFUs?
New ANSI/AAMI Standard Transforms Ethylene Oxide Sterilization in Health Care
July 8th 2024The updated ANSI/AAMI ST24 standard outlines requirements for ethylene oxide sterilizers in health care, addressing advancements, regulatory changes, and new technology to enhance sterilization practices and safety.
The Value of Certification in Infection Prevention and Control: Why Is it important?
May 14th 2024Certification in infection prevention and control is essential for career growth, higher salaries, and improved patient outcomes. Learn why certification matters from Shazia Irum, MSC, MBA, RN, CIC, CPHQ, CBIC Ambassador in Saudi Arabia.