Introduction Since 2000, a considerable increase in the number of Clostridium difficile infections (CDIs) leading to substantial morbidity, mortality and attributable costs has been observed, at least in North America and Europe [1]. Changes in the epidemiology of CDI have been mainly attributed to the emergence of a new hypervirulent strain called PCR ribotype 027, causing numerous outbreaks in North America and Europe [2,3] and, to a lesser extent, PCR ribotype 078 [1,4,5]. In addition, patients not previously considered to be at risk for the disease (e.g., without recent antibiotic therapy or hospitalisation) have also been described [1,6-8]. The European CDI study (ECDIS), initiated and funded by the European Centre for Disease Prevention and Control (ECDC), showed that the incidence of CDI varied from hospital to hospital [9]. In 2008, a weighted mean incidence of 4.1 cases (range: 0.0–36.3) per 10,000 patient-days per hospital reported by the ECDIS study was almost 70% higher than that reported in a previous European surveillance study in 2005 (2.45 cases per 10,000 patient-days per hospital, range: 0.13–7.1) [9,10]. ECDIS also revealed the contribution of strains other than PCR ribotype 027 and that some of these strains, notably PCR ribotypes 015, 018 and 056, could cause severe CDI. In response to the emerging problems associated with C. difficile, an ECDC working group published background information about the changing epidemiology of CDI, CDI case definitions and surveillance recommendations [2]. To support European Union (EU)/European Economic Area (EEA) Member States in increasing their capacity for CDI surveillance, ECDC also initiated and funded a new project – ECDIS-Net – to develop a European surveillance protocol and enhance laboratory capacity for diagnosis and typing of C. difficile in EU/EEA Member States. In 2011, a survey of existing CDI surveillance systems in European countries was performed as part of the ECDIS-Net project. The results of this survey, presented here, were later used to develop a standardised pan-European CDI surveillance protocol, which was tested in a three-month pilot study in 2013 [11]. Data collection in the ECDC-coordinated Europe-wide hospital-based CDI surveillance, using a finalised version of this piloted protocol, began on 1 January 2016 [12]. Methods National coordinators for this study were identified through the members of ECDC’s Healthcare-Associated Infections surveillance Network (HAI-Net) and via representatives for the ECDIS study [9]. A link to a web-based questionnaire was sent to these national coordinators to assess the characteristics of existing CDI surveillance systems in European countries. If the national coordinators indicated that CDI was under surveillance in their country, the surveillance protocols were requested and used to augment the information obtained via the questionnaire. Information on the national CDI surveillance systems was entered using a web- based electronic form designed for the purpose of this study. Results Between 6 June and 15 July 2011, 33 of the 35 national coordinators approached from 31 European countries responded to the web-based questionnaire (Iceland and Wales did not respond). Four surveillance systems were excluded from further analysis, as they were not ongoing, comprehensive nationwide surveillance systems, i.e. they were completed one-off studies (two studies from Spain), only regional (Switzerland) or focused only on outbreaks (one system of the Netherlands). In 14 countries, the national coordinators indicated that surveillance of CDI was in place. Of these, surveillance protocols were available from 10 surveillance systems. Thus, 18 CDI surveillance systems from 14 European countries (Austria, Belgium, Bulgaria, Denmark, Finland, France, Germany, Hungary, Ireland, the Netherlands, Sweden and three countries of the United Kingdom (UK), England, Northern Ireland and Scotland) remained available for analysis. Of the 18 surveillance systems, all but one reported national CDI rates annually.
