Battle of the bacteria

Back-stabbing bacteria whose selfish nature makes them act according to their own interests and avoid cooperation with other infection-causing bacteria can actually reduce the severity of infection say scientists in Nottingham.

Researchers from the University of Nottingham have discovered that in Staphylococcus aureus infections, bacteria defective in Quorum Sensing (QS) can benefit from opting out of toxin production and can quickly outnumber other bacteria, thereby reducing infection severity.

“This opens up the interesting possibility of using these uncooperative bacteria to treat infection,” said Eric Pollitt.

The researchers tested their theory by introducing S. aureus into waxworms that subsequently developed infections.

“We found that the QS-deficient bacteria could not only outgrow normal bacteria in the same population, but that they could also invade other cooperating populations to reduce the severity of infection,” Pollitt explained, “The means we could potentially isolate QS-deficient bacteria and use them to treat clinical S. aureus infections.”

Pollitt said new treatments would complement current treatments for infections caused by the bacteria, and would not be based on antibiotics.

“It’s an interesting concept of fighting like with like,” Pollitt said of the paradoxical approach, “This work also highlights that the interactions between bacteria during an infection can be just as important as the interactions between the bacteria and the host.”

Bacteria usually use QS – where bacteria communicate to coordinate the release of toxins – to overrun their host and lead to severe infections. However, because QS-deficient bacteria opt out, they can invest more energy in reproducing rather than producing toxins and quickly outnumber other bacteria. They also take advantage of the nutrient-rich infection being maintained by their neighbours, and reduce the infection in the host.