The SPARE-SEA consortium observed a high prevalence of colistin resistant bacteria, particularly in Vibrio, in oysters across Europe. The team was able to decode a novel resistance mechanism based on a dgkA-eptA operon controlled by the RstA/RstB two component system, that was restricted to the Mediterranean (France, Spain).

Although this operon was not associated to a mobile genetic element, genetic experiments showed that this mechanism can be transferred to sensitive non-Vibrio strains and confer colistin-resistance. PI Delphine Destoumieux-Garzon presented these results in a course at Universidade Federal de Santa Catarina in Brazil to accomplish knowledge transfer outside of Europe. The team is currently investigating the role of these antibiotic resistance mechanisms in several environmental compartments across Europe and also testing environmental triggers on sinks and sources of antibiotic resistance in controlled mesocosm experiments.