Epidemiology of Clostridium difficile infections in Australia: enhanced surveillance to evaluate time trends and severity of illness in Victoria, 2010-2014.
BACKGROUND
With epidemic strains of Clostridium difficile posing a substantial healthcare burden internationally, there is a need for longitudinal evaluation of Clostridium difficile infection (CDI) events in Australia.


OBJECTIVE
To evaluate time trends and severity of illness for CDI events in Australian healthcare facilities.


METHODS
All CDI events in patients admitted to Victorian public hospitals between 1(st) October 2010 and 31(st) December 2014 were reported to the Victorian Healthcare Associated Infection Surveillance System. CDI was defined as the isolation of a toxin-producing C. difficile organism in a diarrhoeal specimen, and classified as community-associated (CA-CDI) or healthcare-associated (HA-CDI). Severe disease was defined as admission to an intensive care unit, requirement for surgery and/or death due to infection. Time trends were examined using a mixed-effects Poisson regression model, and the Walter and Edward test of seasonality was applied to evaluate potential cyclical patterns.


RESULTS
In total, 6736 CDI events were reported across 89 healthcare facilities. Of these, 4826 (71.6%) were HA-CDI, corresponding to a rate of 2.49/10,000 occupied bed days (OBDs). The incidence of HA-CDI was highest in the fifth quarter of surveillance (3.6/10,000 OBDs), followed by a reduction. Severe disease was reported in 1.66% of events, with the proportion being significantly higher for CA-CDI compared with HA-CDI (2.21 vs 1.45%, P = 0.03). The highest and lowest incidence of HA-CDI occurred in March and October, respectively.


CONCLUSIONS
A low incidence of HA-CDI was reported in Victoria compared with US/European surveillance reports. Seasonality was evident, together with diminishing HA-CDI rates in 2012-2014. Severe infections were more common in CA-CDI, supporting future enhanced surveillance in community settings.
Victorian Healthcare Associated Infection Surveillance System Coordinating Centre, Victoria, Australia; Department of Medicine, University of Melbourne, Victoria, Australia. Electronic address: leon.worth@mh.org.au.
L J
LJ
Worth
Victorian Healthcare Associated Infection Surveillance System Coordinating Centre, Victoria, Australia.
T
T
Spelman
Victorian Healthcare Associated Infection Surveillance System Coordinating Centre, Victoria, Australia.
A L
AL
Bull
Victorian Healthcare Associated Infection Surveillance System Coordinating Centre, Victoria, Australia.
J A
JA
Brett
Victorian Healthcare Associated Infection Surveillance System Coordinating Centre, Victoria, Australia; Department of Medicine, University of Melbourne, Victoria, Australia.
M J
MJ
Richards
D000368:Aged; D000369:Aged, 80 and over; D016360:Clostridioides difficile / Q000302:isolation & purification*; D003015:Clostridium Infections / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology*; D003967:Diarrhea / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology*; D062665:Epidemiological Monitoring; D005260:Female; D006268:Health Facilities; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012621:Seasons; D012720:Severity of Illness Index; D014739:Victoria / Q000453:epidemiology
Clostridium difficile; Epidemiology; Severe disease; Surveillance; Time trends