As of 2005, outbreaks with “hypervirulent” Clostridium difficile PCR polymerase chain reaction (polymerase chain reaction) ribotype 027 were recognized in the Netherlands. Soon after their recognition, the Center for Infectious Disease Control (CIb Centre for Infectious Disease Control (Centre for Infectious Disease Control)) of the National Institute for Public Health and the Environment (RIVM) started a typing service for Clostridium difficile at the Leiden University Medical Center (LUMC Leids Universitair Medisch Centrum (Leids Universitair Medisch Centrum)).

This “ad hoc typing” was offered to all microbiological laboratories in the Netherlands. Medical microbiologists in the Netherlands were requested to send Clostridium difficile samples from patients with severe CDI and from outbreaks to the Reference Laboratory Surveillance; resulting in recognition of new emerging C. difficile PCR polymerase chain reaction (polymerase chain reaction) ribotypes, such as Type 078, which was also found increasingly in other European countries. As of May 2009, a sentinel surveillance was added with continuous monitoring of CDI in approximately 20 hospitals collecting a minimum of clinical and epidemiological and characterization of C. difficle isolates at the LUMC Leids Universitair Medisch Centrum (Leids Universitair Medisch Centrum). The Reference Laboratory is now able to recognize 164 PCR ribotypes. In 2012, two new PCR ribotypes were added to the Reference Laboratory library.

In the period between May 1st 2012 and May 1st 2013, 296 samples from 17 healthcare facilities and laboratories in the Netherlands were investigated at the Reference Laboratory in Leiden for ad hoc typing. PCR ribotype 027 was more frequently found (20%) compared to 2011-2012 (15%). This is attributable to a large outbreak encompassing at least 69 isolates from a hospital and surrounding nursing homes in the eastern part of the Netherlands. We also found isolates that were related to this particular strain in three hospitals using MLVA Multi-Locus Variable number of tandem repeat Analysis (Multi-Locus Variable number of tandem repeat Analysis), of which two in another part of the country.

The results of the sentinel surveillance in the period May 2012-May 2013 in 19 hospitals showed that the mean incidence of CDI was 14.7 per 10,000 hospital admissions, varying from 5 to 27 per 10,000 admissions. This incidence is similar as the incidence of 15 per 10,000 admissions that was reported the recent two years. The most frequent encountered PCR ribotypes were Type 014 (16%), Type 001 (14%), Type 078 (12%), Type 002 (6%) and Type 005 (5%). Of all (n=911) C. difficile isolates, 28 (3%) belonged to Type 027; no Type 027-like PCR ribotypes (016, 036,176) were found. A total of 150 patients (25%) had severe CDI. Within 30 days, six patients had been admitted to the ICU intensive care unit (intensive care unit) and two underwent surgery as a consequence of CDI; 56 patients with CDI (11%) died. Twelve deaths were attributable or contributable to CDI. Extrapolating the data of sentinel surveillance to all hospitals in the Netherlands, it is estimated that more than 2900 hospitalized patients annually will develop CDI. In these estimations, the impact of CDI in other healthcare facilities than hospitals was not included. Therefore, the true number of patients with CDI admitted to healthcare facilities will be higher.

We conclude that Type 027 is re-emerging related to outbreaks in two healthcare facilities in different parts of the country. The proportion of Type 027 in the ad hoc typing increased to 20%, however, the proportion of Type 027 in the sentinel surveillance is stable at 3%.