Prevalence of multidrug resistant bacteria and Clostridium difficile in Dutch hospitals, 2007-2009

Background: Since 2007 the PREZIES national network for the surveillance of nosocomial infections (NI) in the Netherlands organizes a national prevalence study twice a year.

Objective: Furthermore data on the presence (colonization or infection) all anytime during the admission until the survey day of meticillin resistant Staphylococcus aureus (MRSA), extended spectrum beta-lactamase producing bacteria (ESBL), vancomycin resistant enterococci (VRE) and Clostridium difficile. was collected to assess the burden with these (multidrug resistant) bacteria in Dutch hospitals and possible trends therein.

Methods: All inpatients of one year and older, which have been admitted before the survey day are included, with the exception of patients in psychiatry and (haemo)dialysis.
The surveillance can be done during the whole month (March and/or October) but patients of one ward have to be included on the same day.

Results: From March 2007 up to and including March 2009, 5 surveys have resulted in data on 37,601 patients, from 50 hospitals (53% of all Dutch hospitals), of which 76% participated => 1 time. The average prevalence of NI was 6.6%,  the proportion of patients with NI 5.8%. Table 1 shows the average prevalence of the MDR micro-organisms and C. difficile per survey.
The percentages for MRSA and C. difficile remained more or less constant. The percentage of patients positive for ESBL showed a significant increase (p<0.0001) over the 2.5 years. Seven hospitals participated all five periods and showed a significant increase too (0.2, 0.3, 0.4, 0.4 and 0.8 respectively). The high percentage of patients with VRE in March 2009 could partly be contributed to a high frequency in one hospital. However, when only the number of hospitals with VRE was considered the increase was conspicuous too.
In the Netherlands, MRSA is routinely screened for in patients formerly admitted in foreign hospitals, in calf and pig farmers, their family members and in known MRSA contacts. Therefore the proportion found cannot be interpreted as the prevalence of MRSA infection. For VRE only contact screening, in specific wards, is recommended. For the other organisms there are no screening recommendations.

Conclusions: The proportion of patients with C. difficile and MRSA colonization/infection did not increase during 5 successive surveys. The prevalence of ESBL increased significantly over the last 2.5 years. Table I Percentage of patients positive for multidrug resistant organisms and Clostridium difficile per survey.

	March 2007	October 2007	March 2008	October 2008	March 2009
Number of patients	8,424	3,497	9,449	5,760	10,471
Number of hospitals	30	12	29	21	37
MRSA	0.2	0.2	0.2	0.1	0.3
ESBL	0.5	0.4	0.6	0.6	1.0
VRE	0.04	0.03	0.03	0.02	0.2
proportion of hospitals with VRE	6.7	8.3	10.3	4.8	16.2
C. difficile	0.5	0.3	0.6	0.1	0.3