C. William Keevil
Chair in Environmental Healthcare
Head of the Microbiology Group
University of Southampton, Southampton, UK
Horizontal gene transfer (HGT) conferring resistance to many classes of antimicrobials has resulted in a worldwide epidemic of nosocomial and community infections caused by multidrug-resistant microorganisms, leading to suggestions we are returning to the pre-antibiotic era. Whilst studies have focussed on HGT in vivo, this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role. Here we show prolonged survival of multidrug resistant Escherichia coli and Klebsiella pneumoniae on stainless steel surfaces for several weeks.
Plasmid mediated HGT of β-lactamase genes conferring resistance to third generation extended spectrum beta lactams and fourth generation carbapenems occurred to an azide-resistant recipient E. coli if donor and recipient cells were mixed together on contemporary stainless steel surfaces and in suspension but not on copper alloy surfaces. This transfer occurred almost instantaneously, even when the surface was dry and the pathogens survived many days of dry contact, providing an environmental hygiene risk and a reservoir for the acquisition and dissemination of new antibiotic resistant strains. In addition, rapid death of both antibiotic-resistant strains and destruction of plasmid and genomic DNA was observed on copper and copper alloy surfaces, mediated by Cu+ and reactive oxygen species. This could be useful in the prevention of infection spread and gene transfer in the healthcare and public transportation environments, particularly where efficient cleaning and disinfection practice is not 24/7.