'Good' bacteria can battle 'bad' bacteria in eye infections

Scientists have found a novel way to attack the drug resistant bacteria that cause eye infections resulting in blindness.
The study led by Daniel Kadouri, an assistant professor of oral biology at the University of Medicine and Dentistry of New Jersey had three major components.
The first established that isolates of two antibiotic-resistant ocular pathogens, Pseudomonas aeruginosa and Serratia marcescens, were all susceptible to being attacked and killed by at least one of two other bacteria, Micavibrio aeruginosavorus and Bdellovibrio baceriovorus.
The latter two bacteria act as predators against the pathogens but are believed to be "good," or non-infectious, bacteria when they exist within the human body, researchers said.

In the second phase, human corneal-limbic epithelial cells that are native to the eye were exposed in vitro to M aeruginosavorus and B baceriovorus to test whether those "good" predator bacteria would cause either toxicity or inflammation in those cells, which they did not.
In the third phase, the two "good" predator bacteria were injected into live worms from the species Galleria mellonella, which is well established as a suitable model to test the toxicity of various microbes as well as a live organism's innate immunity to those microbes.

Where injection of the pathogenic bacterium aeruginosa as a positive control was one hundred per cent fatal to the worms, other worms injected with the two "good" predator bacteria had 11-day survival rates between 93.3 and 100 per cent, a strong sign that the "good" bacteria were not toxic to the worms.

In addition a lack of change in larval pigmentation following injection suggested that the "good" bacteria also did not provoke an aggressive innate immune response in the worms.
"Taken together, our findings leave us confident that, in isolation, pathogenic bacteria are susceptible to successful attack by predator bacteria, predator bacteria do not appear inherently harmful to ocular cells when applied topically, and a live organism can tolerate the predator bacteria well," said Kadouri.
"The time to test all three phenomena simultaneously in the eye tissue of a live organism may now be at hand," Kadouri said.
The current study presents hope that a wide variety of multidrug resistant (MDR) bacteria may be susceptible to attack by predatory bacteria in settings where antibiotic therapy has increasingly failed.

The study was published in the journal PLoS ONE.