In order to study the incidence of CDI in endemic situation, a new sentinel surveillance started in May 2009. Nineteen hospitals participate in this surveillance and introduced a continuous monitoring of CDI. This is the second annual report that provides an overview of the two types of surveillance conducted in the Netherlands. The previous report showed that the incidence in the Netherlands is stable at 15 per 10,000 admissions and the most frequently found types are 001, 078 and 014. In this annual report we describe the situation in the Netherlands between May 1st 2010 and May 1st 2011.

As of 2005, outbreaks with 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 national Reference Laboratory for Clostridium difficile at the Leiden University Medical Center. All 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 resulted in recognition of new C. difficile PCR ribotypes, such as Type 078 which was also found increasingly in other European countries.

In the period between May 1st 2010 and May 1st 2011, 274 samples from 28 healthcare facilities and laboratories in the Netherlands were investigated at the Reference Laboratory in Leiden. In contrast to previous years, type 027 was the most commonly found PCR ribotype (25.5%), followed by type 001 (17.3%), type 014 (12.5%) and type 078 (9.6%). The increased share of type 027 was due to two large outbreaks. The largest outbreak due to type 027 took place in an elderly home. This outbreak is now lasting for over one year.

The results of the sentinel surveillance in 20 hospitals revealed that the mean incidence of CDI is 15 per 10,000 admissions, varying from 5 to 33 per 10,000 admissions. Type 001 was the most frequently found type (20%), type 014 was found in 13% and type 078 in 12%. Type 027 was found in 3%. A total of 129 patients (20%) had severe CDI. After 30 days, 7 patients (1.3%) were admitted to the ICU intensive care unit (intensive care unit) as a consequence of CDI; 68 patients with CDI (12.8%) died. Two deaths were attributable to CDI, 16 deaths were contributable to CDI.

Extrapolating the data of sentinel surveillance to all hospitals in The Netherlands, it is estimated that more than 2700 hospitalized patients annually will develop CDI of which 100 will succumb attributable or contributable to 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.

Between May 1st 2010 and May 1st 2011 twelve outbreaks were seen in the sentinel surveillance and five in the Reference Laboratory. These outbreaks were caused by types 001, 014, 078, 087 and type 027.

No new PCR ribotypes were identified. The Reference Laboratory is now able to recognize and name 134 types. Additionally, 130 unknown types were recognized by the Reference Laboratory between 2005 and 2011. Of these types, 12 different types occurred more than 5 times and were sent to the NHS neonatale hielprikscreening (neonatale hielprikscreening) Clostridium Reference Laboratory in Cardiff, Wales for further typing. All the unknown types from 2010 were also further characterized for the presence of TcdA, TcdB and Binary toxins.

We conclude that type 027 is again becoming the predominant type in healthcare facilities that do not participate in the surveillance. This is due to two large outbreaks caused by this strain. Besides these outbreaks, the incidence seems stable, with types 001, 014 and 078 as the predominant types.