Setting

Greece is a country in southern Europe with a population of ca 11 million as of 2016. Athens is the nation's capital and largest city (ca 3 million residents), followed by Thessaloniki (800,000 residents). Participating hospitals included 15 public and private tertiary- and secondary-care hospitals: eight in the Athens metropolitan area, three in Thessaloniki (northern Greece), one in Crete, the largest and most populous of the Greek islands in southern Greece, two in central Greece and one in western Greece, representing 12% of Greek hospitals.

The study was organised by the Hellenic Society of Chemotherapy in collaboration with the Infectious Diseases Laboratories of Hygeia Hospital, Athens and of the 4th Department of Internal Medicine of National and Kapodistrian University of Athens, where the susceptibility testing and molecular studies were performed. A nationwide multicentre surveillance network was formed by the microbiology laboratories of participating hospitals, which were asked to provide all consecutive single-patient K. pneumoniae clinical strains, isolated in a 6-month period and exhibiting non-susceptibility to any carbapenem (imipenem, meropenem or ertapenem) for further testing. These isolates were re-submitted for susceptibility testing as well as phenotypic and molecular detection of carbapenemases at a central laboratory.

Data on the source and the date of isolation as well as the initial susceptibility results at the local laboratories were also provided. All isolates were transferred to the Microbiology Laboratory of Infectious Diseases of Hygeia Hospital and kept frozen at −80 °C until the day of testing.