Travelers import superbugs

Many tourists returning from India were found colonized with multidrug-resistant 'superbugs'. Microbiologists at the Institute for Infectious Diseases of the University of Bern also isolated a strain possessing a gene which can make these life-threatening bacteria resistant to the last active antibiotic option. The spread of multidrug-resistant Gram-negative bacteria represents a serious issue for the healthcare system worldwide because our antibiotic armamentarium is becoming too limited. These 'superbugs' may cause serious infections with high morbility and mortality rates - there are already 700'000 estimated deaths per year worldwide because common antimicrobial therapies have become ineffective. In this scenario, colistin has represented the last active antibiotic option able to cure many infected people. Unfortunately, in November 2015 a new mechanism of resistance against colistin was found with a high prevalence in Escherichia coli and Klebsiella pneumoniae strains detected in China among humans, food animals, and chicken meat; more recently, it has also been found in other countries. This mechanism is encoded by a gene (named mcr-1) that is plasmid-mediated, thus assuring its great ability to mobilize and spread between different enterobacteria, including those normally present in the human and animal intestinal tracts.