Boston University researchers have found that taking low levels of antibiotics that don't quite destroy bacteria can turn them into superbugs.

While treating bacteria with insufficient levels of antibiotics produces germs that are cross-resistant to a wide range of antibiotics and when the level of antibiotic is less than lethal, the same reaction causes DNA mutations that are not only survivable, but actually protect the bacteria from numerous antibiotics.

Strains of E. coli and Staphylococcus were used by the researchers to test the effect of low level antibiotics and the scientists observed the effect of five different antibiotics on the bacteria, finding that doses that were less than lethal to the germs made them resistant to other antibiotics.

However, James J. Collins of Boston University said that antibiotics trigger a fatal chain reaction within the bacteria that shreds the cell's DNA. In effect, what doesn't kill them makes them stronger.

Findings ways to stop antibiotic resistance might also be accomplished by developing antibiotics that boost free radical production to destroy bacterial cells using low doses of antibiotics.