New York Oct 6 (IANS): In a major breakthrough, scientists have developed the world's first 'programmable' antibiotic technique that selectively targets the bad bugs - particularly those harbouring drug-resistance genes - while leaving innocent microbes alone.

"In lab experiments, we succeeded in instructing a bacterial enzyme known as Cas9 to target a particular DNA sequence and cut it up," informed lead researcher Luciano Marraffini.

The Cas9 enzyme is part of a defence system that bacteria use to protect themselves against viruses.

This selective approach leaves the healthy microbial community intact.

"By doing so, you can keep resistance in check and also prevent certain types of secondary infections, eliminating two serious hazards associated with treatment by classical antibiotics," explained Marraffini who is head of laboratory of bacteriology at the Rockefeller University in the US.

For instance, the new technique can reduce the risk of C. diff - a severe infection of the colon caused by the Clostridium difficile bacterium that is associated with prolonged courses of harsh antibiotics.

"Depending on the location of the target in a bacterial cell, Cas9 may kill the cell or it may eradicate the target gene, thereby preventing a cell from acquiring resistance," researchers pointed out.

In addition to its potential as a much-needed new weapon against drug-resistant microbes, the new system could also be used to advance research on the complex populations of microbes in the body, about which very little is known.

The research paper appeared in the journal Nature Biotechnology.