Exposure to One Antibiotic Leads to Acquisition of Resistance to Another Antibiotic Quorum Sensing Mechanisms.

The vancomycin-resistant Enterococci (VRE) have progressively become a severe medical problem. Although clinics have started to reduce vancomycin prescription, vancomycin resistance has not been contained. We found that the transfer of vancomycin resistance in increased more than 30-fold upon treatment by streptomycin. Notably, treatment with an antibiotic caused the bacteria to become resistant to another. The response was even stronger in the well-studied plasmid pCF10 and the number of transconjugants increased about 100,000-fold. We tested four different antibiotics, and all of them induced conjugal response. Through a mathematical model based on gene regulation, we found a plausible explanation. quorum sensing, the change of the cell density triggers the conjugation. Moreover, we searched for generality and found a similar strategy in . The outcome of the present study suggests that even common antibiotics must not be overused.