Ziekenhuisuitbraken en resistente micro-organismen

Akke K. van der Bij, Katina Kardamanidis, Florine N.J. Frakking, Marc J.M. Bonten en Signaleringsoverleg Ziekenhuisinfecties en Antimicrobiële Resistentie

Nosocomial outbreaks and resistant microorganisms

This supplementary information is presented as submitted by the corresponding author. It has not been copy-edited by NTvG.


In response to perceived lack of transparent reporting of nosocomial outbreaks in Dutch hospitals, a ‘Hospital-Acquired Infection and Antimicrobial Resistance Monitoring Group (HAI&AR Monitoring Group)’, especially for highly-resistant microorganisms (HRMO), was implemented in April 2012. Hospitals are requested to report any nosocomial outbreak that potentially impacts the delivery of health care (e.g., because of the necessity to close wards) or when transmission continues despite infection prevention control measures. The HAI&AR Monitoring Group categorizes the status of reported outbreaks, based on voluntarily provided information, on a monthly basis, ranging from 1 (newly reported) to 5 (inadequate control despite extensive measures or due to non-cooperation of a hospital). Here we describe the findings until June 2014.


Descriptive characteristics were collected at the start and end of each outbreak, such as type of (resistant) microorganism, reason for reporting, categorization of outbreaks, number of patients colonized and infected, and implemented infection prevention measures.


Between April 2012 and June 2014, 47 medical institutions reported 87 outbreaks (mean of 3 outbreaks per month). In 2012, the number of outbreaks reported was 20 (2.2/month); in 2013, 39 (3.3/month); and in the first six months of 2014, 28 (4.7/month). Non-reported outbreaks were not identified from other sources, such as media or health care professionals. Outbreaks with Vancomycin-Resistant Enterococci (VRE, n=26) and Methicillin-Resistant Staphylococcus aureus (MRSA, n=23) and highly-resistant Enterobacteriaceae (n=17) were reported most frequently. Other pathogens causing outbreaks were norovirus (n=4), astrovirus (n=1), measles virus (n=2), Clostridium difficile (n=9) and Pseudomonas aeruginosa (n=4). Sixty-five outbreaks (75%) were controlled within two months (highest category phase 1). Four outbreaks with VRE and two with C. difficile were classified as phase 3 (a possible threat for public health), but all six were adequately controlled. None of the outbreaks were considered a threat to public health. Seven outbreaks in nursing homes or long-term care facilities were reported and this number seems to be increasing (1 in 2012, 2 in 2013 and 4 in the first six months of 2014).

Thus far, final epidemiological data, such as duration of the outbreak and total number of affected and infected patients were collected of 49 of the 87 outbreaks (56%). These additional data showed that outbreaks with VRE and C. difficile lasted longer than outbreaks with other pathogens and had the highest numbers of patients affected. The median duration of outbreaks with VRE and C. difficile was 90 (range 21-256) days and 64 (range 6-278) days. For MRSA the median duration of the outbreaks was 40 (range 14-153) days and for HRMO Enterobacteriaceae 52 (range 33-120) days. The median number of colonised patients in VRE outbreaks was 9 (range 3-483), while for MRSA the median number was 5 (range 1-18) patients. In outbreaks with C. difficile the median number of patients infected was 43 (range 5-515).


Hospital outbreaks with HRMO and other pathogens occur frequently in Dutch hospitals, and are mostly controlled within two months without impact on public health. There seems to be maximum transparency about hospital outbreaks of HRMO since all outbreaks meeting the reporting criteria were reported to the HAI&AR Monitoring Group. VRE and MRSA outbreaks occur most frequently, whereas outbreaks with VRE and C. difficile have the highest impact on patient care. Due to frequent patient transfer between nursing homes or long term care facilities and hospitals, the HAI&AR Monitoring Group will start to actively involve these health care facilities to gain insight in the occurrence of outbreaks with HRMO within these settings.