Reduction of Clostridium difficile incidence, Finland, 2008-2009

Background: In January 2008, surveillance of C. difficile-associated infections (CDI) started as a part of the Finnish National Infections Disease Register (NIDR), and enhanced surveillance by the Finnish Hospital Infection Program (SIRO).

Objective: We present here the first two year data.

Methods: All laboratories reported C. difficile findings (positive culture and/or toxin production) from stools to NIDR. Each notification included specimen date, each individual’s unique national identity code, date of birth, sex and place of residence. Within this information and 3-month time interval, multiple notifications of the same person were merged as a single CDI episode which was defined as detection of toxin positive C. difficile from stools. The surveillance of hospitalized patients with CDI was conducted using the interim case definitions of the European Centre for Diseases Prevention and Control for CDI, origin and severe case of CDI. 13 acute care hospitals from 7/20 healthcare districts (HD) took part in SIRO during 2008-2009. Clinical microbiology laboratories were asked to send isolates from severe cases and persistent outbreaks to the national reference laboratory for genotyping.

Results: The annual incidence rate of CDI decreased by 10%, from 119/100,000 population in 2008 to 107 in 2009. The decrease occurred in 10/20 (50%) HDs (range of decrease by HD, 5-36%) and in 7 HDs with the rates above the national mean in 2008 it varied between 19-34%. In 8/13 (62%) hospitals that participated in SIRO the nosocomial rates of CDI decreased 6-62%. Only in one HD, there was a discrepancy in the direction of change: the nosocomial rate in one hospital decreased 6% although there was a concomitant total increase of 9% in the annual population-based incidence rate in the HD. The population-based rate decreased also in 7/13 (54%) HDs where there were no participating hospitals in SIRO. 15/20 HDs sent 602 isolates for typing of which 189 (31%) were of ribotype 027: 3/7 HDs (43%) with 027 had decreasing population-based CDI incidences and in 4/7 HDs (57%) with 027 had increasing incidences.

Conclusions: Both population-based and enhanced surveillance of CDI showed clear decrease in CDI incidence. The first CDI case due to ribotype 027 was identified in Finland in October 2007 along with development of typing measures. The decrease in CDI incidence between 2008 and 2009 was unlikely only related to decreased diagnostic activity but due to increased awareness of CDI and control measures. However, the success varied in different regions, which underlines the importance of exchanging experiences in controlling CDI. Enhanced CDI surveillance covered acute care hospitals in one third of the HDs and showed similar trend than the population-based surveillance. However, SIRO participation was not related to the decreases in the population-based incidences.