Research finds synergistic antibiotics can have opposite effects on you.
Did you ever take two or more antibiotics in order to get rid of a disease? New research in PLOS Biologysuggests that this is not a wise thing to do. Drug resistant bacteria grow faster than their weaker counter parts when resources are limiting and many antibiotics are consumed.
A team of evolutionary biologists from University of Exeter in the United Kingdom explain this by putting antibiotic synergy into test. They were able to prove using mathematical modeling, evolution experiments, whole genome sequencing and genetic manipulation that deploying synergistic antibiotics is the worst strategy.
They added two kinds of antibiotics (oxycycline and erythromycin) to tubes full of E. coli to see how well microbes are able to grow in such a harsh environment.
As expected, initially a decrease of 95% was observed in bacterial populations that were subjected to synergistic attack. However, after one and a half day an overwhelming 500% growth was seen for the bacterial population that had dropped almost 90% after antibiotic exposure initially.
This was tested again for confirmation and same results were obtained every time. Synergist cells suppress drug-susceptible subpopulations more than single drug therapies but at the same time this also eliminates all competitors of drug-resistant cells which grow more rapidly.
The study shows bacterial genes had widely duplicated genes which provided way for such a behavior. Whole genome sequencing revealed genetic amplification of four drug resistant regions including acrAB efflux operon. Basically, these provided more “efflux pumps” that thrust drugs into extracellular space, or the periplasm, thus conferring resistance to a wide range of drugs in many species. Though two-pronged attacks don’t always work but why to take a chance. This research helps in generating awareness that unless super-inhibitory doses are achieved as well as maintained and until the pathogen is successfully cleared; synergistic antibiotics can have the opposite effect to that intended by helping clear the bacterium rapidly.
Source:
Pena-Miller R, Laehnemann D, Jansen G, Fuentes-Hernandez A, Rosenstiel P, Schulenburg H, & Beardmore R (2013). When the most potent combination of antibiotics selects for the greatest bacterial load: the smile-frown transition. PLoS biology, 11 (4) PMID: 23630452