Medical Care

Predicting Superbugs' Countermoves to New Drugs

With drug-resistant bacteria on the rise, even common infections that were easily controlled for decades such as pneumonia or urinary tract infections are proving trickier to treat with standard antibiotics.New drugs are desperately needed, but so are ways to maximize the effective lifespan of these drugs.

To accomplish that, Duke University researchers used software they developed to predict a constantly-evolving infectious bacterium’s countermoves to one of these new drugs ahead of time, before the drug is even tested on patients. The software they developed, called OSPREY, is open-source and freely available for any researcher to use.

A release from the university explains that In a study appearing in the journal Proceedings of the National Academy of Sciences in January 215, the team used their program to identify the genetic changes that will allow methicillin-resistant Staphylococcus aureus, or MRSA, to develop resistance to a class of new experimental drugs that show promise against the deadly bug.

When the researchers treated live bacteria with the new drug, two of the genetic changes actually arose, just as their algorithm predicted.

The release quotes co-author Bruce Donald, a professor of computer science and biochemistry at Duke, as saying, “This gives us a window into the future to see what bacteria will do to evade drugs that we design before a drug is deployed.”

Developing pre-emptive strategies while the drugs are still in the design phase will give scientists a head start on the next line of compounds that will be effective despite the germ’s resistance mutations.

“If we can somehow predict how bacteria might respond to a particular drug ahead of time, we can change the drug, or plan for the next one, or rule out therapies that are unlikely to remain effective for long,” said Duke graduate student Pablo Gainza-Cirauqui, who co-authored the paper.

Because bacteria reproduce so rapidly — growing and dividing from one cell to two in less than an hour — drug-resistant bacteria are constantly evolving, and researchers have to constantly develop new ways to kill them.

Image credit, Lei Chen and Yan Liang, Duke University

Since the first antibacterial drugs were introduced in the 1940s, bacteria have evolved ways to resist every new antibiotic that has been developed — a process that has been accelerated by the use of antibiotics in livestock to help them gain weight, and in humans to treat viral infections that antibiotics are powerless to cure.

“My kids are now 15 and 13, and some of the antibiotics they were given when they were little aren’t given anymore because they aren’t as effective,” Donald said.

The percentage of infections caused by the bacterium Staphylococcus aureus that have proven resistant to treatment has risen steadily from just over 2 percent in 1975 and 29 percent in 1991 to more than 55 percent today — resulting in more than 11,000 deaths in the U.S. each year, a higher death toll than HIV.