Tiny drug delivery system could help treat bacterial infections

People infected with Streptococcus pneumoniae and Gardnerella vaginalis often have to take more than one round of antibiotics to battle the infection. That means they have to deal with symptoms for longer and it could contribute to antimicrobial resistance (AMR).Researchers from University of Waterloo School of Pharmacy in Waterloo, Ont., have developed a method that could deliver antibiotics in a more effective way, using a system where the drug is delivered in response to toxins produced by specific bacteria species. The pre-clinical studies show promise.“Compared to traditional therapies that release drugs continuously, even when not needed, our nanomedicine is designed to release drugs only when required, which will potentially reduce severe side effects associated with excess dosing,” said Emmanuel Ho, lead researcher and a professor at University of Waterloo’s School of Pharmacy in a press release from the school. “In addition to combatting AMR by ensuring patients take all of their medicine, there would be fewer side effects because they also don’t take too much of the drug. Our technology is far-reaching, and this is just the beginning.” The researchers developed a drug-delivery platform using liposomes capable of encapsulating a drug. The prepared liposomes are tiny, with an average diameter of 300 nanometres. Read: Are you prepared to answer questions about Listeria?In one study, the researchers examined the drug-delivery platform with Gardnerella vaginalis, the most common pathogen in bacterial vaginosis. Bacterial vaginosis occurs when healthy flora of the vagina, (i.e. Lactobaccilus species), is replaced by other overgrown bacteria. It impacts quality of life and puts those infected at risk for pelvic inflammatory disease and sexually transmitted infections. To date, intravaginal antibiotic treatment is the most effective, but the continuous drug delivery it involves can lead to adverse effects due to excess doses.The researchers designed the liposome platform to release calcein in the presence of vaginolysin, a toxin secreted specifically by Gardnerella vaginalis. Calcein is a fluorescent dye. Ho and colleagues combined the calcein-containing liposomes and Gardnerella vaginalis, which was grown in a petri dish.The results suggest that the liposome platform can release 46.7%-to-51.8% of the drug over a three to five-day-long period, depending on the formulation used. Importantly, the liposomes released only a minimal amount of calcein when in the presence of the healthy bacteria Lactobacillus crispatus.“We have proved that this platform has great potential to achieve on-demand therapy for bacterial vaginosis relapse prevention and treatment without concerns of excess dosing,” the researchers wrote.The researchers conducted a similar study to examine drug delivery against Streptococcus pneumoniae. The liposome platform for that study carried the antibiotic nisin, and was designed to deliver the drug in response to the presence of the toxin pneumolysin. Liposomes with a high cholesterol levels worked best at delivering nisin when combined with Streptococcus pneumoniae.“Given further development, this cholesterol-rich liposomal platform presents itself as a potential specified treatment strategy for invasive pneumococcal disease to address the ongoing concern of bacterial resistance,” the authors wrote, but noted that the high cholesterol needed for the liposome drug-delivery platform might introduce some challenges when in the human body.The team is hoping to further develop the technique and also test its application in food industry, with a hope it will improve shelf life.The research expands on other systems that deliver drugs based on a stimulus, such as a change in pH or over-expression of reactive oxygen species. Drug delivery based on a toxin is far more specific, the researchers wrote. The research appears as two studies, with the bacterial vaginosis study in Nanotechnology and the Streptococcus pneumoniae study in Drug Delivery and Translational Research.Read: Walking pneumonia is on the rise but treatable with the right antibiotic: doctors

Tiny drug delivery system could help treat bacterial infections

Register for free access or login.

Related Topics