Tackling antibiotic resistance!

Tackling antibiotic resistance!

A scientific team has developed a new way to identify second-line antibiotics that may be effective in killing germs already resistant to a first-line antibiotic - potentially helping overcome antibiotic resistance. This new research provides an approach clinicians could consult when deciding which antibiotic treatment courses will be most effective for patients. The method is based on a mathematical model created by the principal investigator of a recent Nature Communications study.

In the new study, the authors administered a panel of different antibiotics to 60 E. coli strains that had been made resistant to cefotaxime. They then assessed whether the E. coli were killed off at higher or lower rates than E. coli that had not been made resistant to cefotaxime. By using a much larger number of trials than is typical, the researchers overcame the problem of skewed results, which can lead clinicians to infer that a replacement antibiotic is more or less effective than it actually is when given to patients.

"Using a large number of what we term 'evolutionary replicates' explicitly accounts for the inherent randomness of evolution," said the author. "If you only carry out a handful of tests, you are likely to miss the complexity of the evolutionary response of a bug to a second antibiotic."

In the case of ticarcillin, one of the antibiotics tested in the study, the researchers found that in only seven of the 60 replicates (11 percent of the time) did the resistant E. coli die at a higher rate compared pair-wise to E. coli not resistant to cefotaxime. "This means that 89 percent of the time, this would be a bad second drug to give when dealing with cefotaxime-resistant E. coli," said the study's lead theorist. The authors found similar low rates of effectiveness for other drugs tested in the same drug family. "These findings serve as a cautionary warning that we may be inadvertently promoting resistance by prescribing follow-through drugs based on too few trials of their effectiveness."

"This paper is a first step in establishing a repository of findings that a clinician could consult in trying to determine how to deal with patients confronting CEF-resistant E. coli and eventually, other superbugs," said the author. "We showed that not only is the common approach of using a few trials often less effective than hoped for, it may actually increase the risk to patients by wasting valuable time and resources in combating a serious infection."