Stronger Antibiotics Linked With Bacteria Evolving Resistance Faster

Combining various antibiotics will not help kill bacteria and in fact, help the bacteria evolve resistance to the drug combination faster, a new study says.

The study included researchers from University of Exeter and Kiel University in Germany. The team first treated E-coli with various combinations of antibiotics.

They found that the bacteria evolved resistance more quickly if it was treated with a strong combination of antibiotics. Researchers say that the bacteria thrive under aggressive treatments. This happens because the strong antibiotics kill all non-resistant bacteria, so the resistant forms of bacteria have very less competition and can multiply faster.

"We were surprised by how quickly the bacteria evolved resistance. We nearly stopped the experiments because we didn't think some of the treatments should be losing potency that fast, sometimes within a day. But we now know that the bacteria remaining after the initial treatment have duplicated specific areas of their genome containing large numbers of resistance genes. These gene copies appear more quickly when the antibiotics are combined, resulting in the rapid evolution of very resistant bacteria," said professor Robert Beardmore, EPSRC Research Fellow from the University of Exeter, according to a news release.

The study is published in the journal PLOS Biology.                                                                               

Centers for Disease Control and Prevention (CDC) says that the threat of microbes getting resistant to a drug isn't isolated to any country, but is a problem faced by the entire world. The U.S., for example, faces some real danger from methicillin-resistant Staphylococcus aureus (MRSA). Recently, the agency announced the rise of nightmare bacteria - carbapenem-resistant Enterobacteriaceae - that have become resistant to the last-resort antibiotics called carbapenems.

"The evidence that combining antibiotics to make a more potent therapy can lead to the creation of more copies of the genes the bacteria needs to be resistant is of real concern," said professor Hinrich Schulenberg from Kiel University in Germany.