In a bid to fight back against antibiotic-resistant bacteria, researchers are now developing germ-eating microbes that will attack all sorts of nasties, including bacterial lung infections, plague and deadly germs that have developed resistance to antibiotics.

It might seem strange to think of microbe-eating microbes, but "actually they're found in almost every ecosystem on Earth", Brad Ringeisen, deputy director of the Biological Technologies Office at the Defence Advanced Research Projects Agency (DARPA), was quoted as saying by the npr.org.

In the study, the team focused on an organism called Bdellovibrio -- a bacterium that swims around with the aid of a corkscrew tail and attacks common germs six times its size.

Bdellovibrio actually bores into larger bacteria and eats them from the inside out.

First, it uses its flagellum, which is stiff and rotates, to swim up to prey. Then it latches on, using tiny appendages "which are little grappling hooks on the surface", explained Liz Sockett, professor at the Nottingham University in the UK. 

It's a bit like a climber attaching to a rock, she noted.

"Bdellovibrio ended up preying upon 145 of the 168 human pathogens we tested, which is pretty remarkable," Ringeisen said. 

Further, the team fished out few survivors, let them multiply, and then let the Bdellovibrio attack them again. If resistance were to develop, this is exactly the scenario where it would appear. 

The team "did this 50 times over a long period", Sockett said, adding "and never got any direct mutants that were resistant".

While, the predators do not entirely wipe out the disease-causing bacteria, as antibiotics might, the unnaturally large doses of Bdellovibrio can reduce bacterial populations by a lot, the researchers said, adding that studies have suggested it is safe on humans. 

However, these predatory bacteria cannot replace antibiotics, Sockett said, adding that if doctors gave a big dose of this bacteria to people, the patients would develop an immune response to it that would hobble future treatment attempts.

Still, the approach could be useful if given as a one-off preventive in advance of an anticipated germ warfare attack, or it could also work in a patient who has an infection that simply doesn't respond to antibiotics, the researchers said.