Bacteria developed to preempt gut pathogens: ‘An additional option, not a replacement for antibiotics’

U.S. researchers developed bacteria that attack gut pathogens in advance, successfully preventing Salmonella infection in mice.

According to Azure Life Science and Virginia Tech on the 17th (local time), a research team led by Associate Professor Brian Hsu genetically engineered harmless E. coli to produce bacteriophages (phages) that infect only Salmonella. The findings were published in the international journal Nature Microbiology.

Phages are viruses that infect bacteria and do not infect humans or animals. The research team focused on the fact that phages and bacteria coexist in the gut for a long time, making it difficult to achieve the high phage density needed to treat an infection.

The team therefore designed harmless E. coli to carry phages that attack only Salmonella. Once the E. coli reach the gut, they release phages that kill Salmonella through lysis, causing the number of phages to surge in the process.

The research team named this combination a “lyto-lysogen.” Salmonella normally detects phage DNA produced by other bacteria and blocks its replication, but the team disguised the phages by inserting Salmonella genes into the E. coli genome.

Rogério Batalioli, a postdoctoral researcher and the paper’s first author, explained, “We tricked Salmonella into thinking that the phages from E. coli were ‘not foreign material.’”

Associate Professor Hsu said, “When E. coli produce anti-pathogen phages and create a protective barrier, Salmonella encounters a high density of phages just after passing through the stomach, when it is at its most vulnerable.”

The research team said it chose Salmonella as a target because it can be fatal to older adults, children and people with HIV, and has a high rate of antibiotic resistance, leading the U.S. Centers for Disease Control and Prevention (CDC) to designate it a high-risk pathogen.

Researcher Batalioli said, “This is not a replacement for antibiotics, but an additional option for fighting infection,” adding, “Expanding the approach to target other bacterial pathogens is also an interesting direction.”

Associate Professor Hsu added, “We have established a framework that can target other bacteria by introducing different phages.”