Increasing incidence of Clostridium difficile infection, Australia, 2011-2012

To the Editor: Slimings and colleagues suggest that strain typing of Clostridium difficile would give greater insight into the epidemiology of this infection in Australia,1 as it has in the United Kingdom,2 demonstrating less inhospital transmission than suspected in the past. We believe this to be the case.

In a 2-year study of symptomatic C. difficile infection at our 350-bed tertiary hospital,3 we identified 262 cases between October 2011 and October 2013. Of these, 150 (57%) were hospital-onset cases after 48 hours of admission. Ribotyping of 147 of these strains showed 44 different types. There appeared to be no secondary cases of diarrhoea from symptomatic patients in our hospital, where patients with C. difficile infection are isolated immediately after being identified.

We identified only one possible cluster of seven cases of ribotype QX076 on a rehabilitation ward between March and September 2013. This ward has only two rooms with ensuite toilet facilities, with most toilets being shared by four patients. When a toilet is flushed without the lid closed, aerosol production may lead to surface contamination within the toilet environment, increasing the risk of case-to-case transmission of C. difficile.4 Apart from this cluster, most cases were singletons. As we found many different ribotypes, it could be hypothesised that cross-transmission is generally rare, with clustering being the exception rather than the rule.

The greatest numbers of cases were found on haematology/oncology and geriatric wards. No cases involving ribotype UK 027 were identified. The most common ribotypes in hospital- and community-onset cases belonged to the UK 014/020 group. There were 53 cases (20%) of community-onset infections without evidence of health care system contact. Fifteen of these had ribotypes not found in the hospital-onset cases.

Further investigations are required to assess the role of asymptomatic carriers in hospital infection and to define the relationship to toilet facilities and cleaning efficacy.