Authors: Julie Kaiser (University of Western Ontario, Canada)
In a recent study published in Nature Communications, researchers have demonstrated that antibiotic-resistance plasmids persist in the absence of antibiotics, provided that the efficiency of plasmid transfer exceeds a critical threshold. Their study highlights the limitations of ‘resistance-reversal’ strategies that aim to reduce resistance-gene transfer by reducing antibiotics in the environment, and reveals a need for small molecules that target plasmid transfer.
Antibiotic-resistance plasmids persist in the environment and act as reservoirs or ‘hot spots’ for the transfer of resistance genes from one bacteria to another. It is thought that the overuse of antibiotics has contributed to the persistence of resistance plasmids by imposing a positive selection for bacteria that carry resistance – perpetuating hot spots and increasing the likelihood of plasmid transfer to human pathogens. Yet antibiotic-resistance plasmids can carry a fitness cost, leading to the idea that in the absence of antibiotics, the sensitive bacteria should outcompete their resistant counterparts.