Vaccine-Probiotic Combo Shows Promise as Antibiotic Alternative in Mice Study

Swiss researchers have developed a novel approach to combat bacterial gut infections without relying on traditional antibiotics, potentially offering a new weapon in the fight against antibiotic resistance. The technique, dubbed "vaccine-enhanced competition," combines an oral vaccine with probiotic supplementation to clear harmful bacteria and promote a healthy gut microbiome.

Innovative Two-Step Approach

Led by immunologist Emma Slack, Ph.D., of ETH Zurich, the research team published their findings in Science on April 3, 2025. The method involves two key steps:

1. An oral vaccine containing inactivated pathogenic bacteria stimulates the immune system to recognize and target harmful microbes.
2. A probiotic supplement introduces beneficial bacteria to colonize the newly cleared gut environment.

"Although we can decimate pathogenic bacteria with a vaccine, we need harmless microorganisms to fill the resulting niche in the intestinal ecosystem in order to achieve long-term success," Slack explained. She likened the process to gardening, emphasizing the importance of replanting after weeding to prevent unwanted regrowth.

Promising Results in Mouse Models

The researchers tested their approach on two common bacterial pathogens:

Salmonella Prevention

To prevent Salmonella infections, mice were given an oral vaccine made from inactivated pathogenic Salmonella cells, along with a probiotic consisting of a genetically engineered harmless Salmonella strain. When later exposed to pathogenic Salmonella, treated mice remained infection-free, while control mice developed gut infections.

E. coli Treatment

In a similar experiment targeting E. coli, the combination of an oral vaccine and three harmless E. coli strains successfully cleared existing pathogenic E. coli infections in mice.

The vaccine-probiotic combination proved more effective than either component alone in both prevention and treatment scenarios.

Future Directions and Potential Impact

While the study used bacterial strains specific to mice, Slack and her team are eager to apply their technique to human-relevant pathogens. The next steps include testing the approach in mice infected with human-pathogenic strains, followed by human clinical trials.

If successful, this vaccine-enhanced competition method could significantly reduce reliance on antibiotics, potentially slowing the spread of antibiotic-resistant bacteria. The technique offers a targeted approach to managing gut bacterial populations without the broad-spectrum effects of traditional antibiotics.

As antibiotic resistance continues to pose a global health threat, innovative strategies like this vaccine-probiotic combination represent crucial avenues for maintaining our ability to combat bacterial infections effectively.