Silver nanoparticles could be the next tool in treating the symptoms of chronic diseases such as cystic fibrosis, according to research from the University of Guelph.

Prof. Cezar Khursigara
Prof. Cezar Khursigara

Researchers in the Department of Molecular and Cellular Biology (MCB) have found that adding silver nanoparticles made antibiotics more effective against certain types of bacteria – and the smaller the nanoparticle, the better the treatment.

Their preliminary findings could lead to methods to control and eliminate drug-resistant bacteria.

Prof. Cezar Khursigara, MCB, worked on the study with researchers from his lab and with Prof. Marc Habash, Environmental Sciences. He said researchers have suspected for a long time that silver could help improve health, but combining silver with antibiotics is relatively new.

“Antibiotics are able to counter most lone bacteria, what we call planktonic cultures, fairly easily,” he said.

“The main issue is what happens when the bacteria come together to form a community structure, known as a biofilm. Then, antibiotics have difficulty penetrating the biofilm, which is protecting the bacteria. It takes more and more medicine to destroy the bacteria. And in time, the bacteria become resistant to the antibiotics.”

The researchers examined the impact of silver nanoparticles and a standard antibiotic, Aztreonam, against the bacteria Pseudomonas aeruginosa, which can lead to serious lung infections in people suffering from cystic fibrosis (CF). CF is a recessive genetic disorder that often leads to frequent lung infections, among other complications. Lung transplants are often necessary as CF worsens.

Khursigara said CF-related infections are often acute or transient in younger patients, meaning it can be treated easily by antibiotics since the pathogens are commonly in their planktonic form. By a patient’s late teens or early 20s, Pseudomonas infections become chronic in people with CF, biofilms form more easily and antibiotics are less successful.

“We hope to extend the effectiveness of antibiotics by using combination treatments,” Khursigara said.

“When we looked closely at the biofilm, we can see particles of silver attach to the bacteria. In essence, the silver is piercing the biofilm and, combined with the antibiotics, is eliminating the biofilm and not allowing it to re-form. Also, the smaller the silver particles, the more effective the combination was – larger nanoparticles had problems piercing the biolfim and antibiotics were less effective in treatment.”

While the results are encouraging, Khursigara said more research is needed before animal testing takes place.

“Why is silver effective? What are the genes, proteins or mechanisms impacted by it? If we find those answers, we can design effective treatments, and not just for CF but for anyone with a weakened immune system susceptible to bacterial infection. This includes people with AIDS or those undergoing chemotherapy. It’s not about finding a magic solution but keeping us one step ahead of diseases.”

The study, “Synergy of Silver Nanoparticles and Aztreonam against Pseudomonas aeruginosa PAO1 Biofilms,” will appear an upcoming issue of the journal Antimicrobial Agents and Chemotherapy.