Corrections and additional information Dagfinn Skaare, Vestfold Hospital Trust 7 August 2014 The complete affiliation information for University of Tromsø is 'Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway'. Arnfinn Sundsfjord lacks the following additional affiliation: 'Reference Centre for Detection of Antimicrobial Resistance, University Hospital of North Norway, Tromsø, Norway'. There is also a minor error in Table 6: in the heading, 'AMP', 'AMC' and 'PIP' have been assigned note 'c'. The correct is note 'd'. Competing interests None.