There has been some recent discussion on whether we should implement screening for asymptomatic carriage of C. difficile. Whilst there is some evidence that cross-transmission of C. difficile from symptomatic cases is rare (in English hospitals, at least), a recent study shows that asymptomatic carriers are an important source of in-hospital transmission of C. difficile.
The study was performed over 4 months in a Danish ICU. All admissions were screened for asymptomatic carriage of C. difficile. The key outcome was that exposure to a C. difficile asymptomatic carrier resulted in an increased risk of C. difficile infection: C difficile infection was detected in 2.6% of patients not exposed to carriers and in 4.6% of patients exposed to asymptomatic carriers (odds ratio 1.8, 95% confidence interval 1.2-2.8). Put another way, patients exposed to asymptomatic carriers were approximately twice as likely to develop C. difficile infection!
One unique aspect of the study was that hospital staff were blinded to the C. difficile carriage status of the patients on the unit. This means that no attempts were made to reduce the risk of C. difficile transmission from known carriers. So, the study provides some tantalising evidence that improving the management of known C. difficile carriers (perhaps through isolation and enhanced disinfection) could reduce the incidence of C. difficile infection.
Patients with C. difficile diarrhoea will shed a lot more spores and need to remain the key focus of prevention and control initiatives. However, this study suggests that asymptomatic carriers should be a separate focus of prevention and control interventions.
We recently posted a blog on a review and meta-analysis on the increased risk of acquiring key hospital pathogens from the prior room occupant. A similar review and meta-analysis has just been published focussing on the ICU environment. The new study highlights the 5-fold increase in risk of acquiring Acinetobacter when the previous room occupant had this pathogen!
The main result is the same from both meta-analyses: the risk of acquiring MRSA, VRE, C. difficile, Acinetobacter, Pseudomonas, and Klebsiella or E. coli is approximately doubled when patients were admitted into rooms where the previous occupant had these pathogens. The presentation of the data grouped by organism in the most recent review draws attention to a greater increase in risk from one pathogen in particular: Acinetobacter. There was a
5-fold increase in risk for this pathogen, which was itself double the increase in risk for all pathogens combined, suggesting that Acinetobacter is somehow "more environmental" than the others*. Whilst differences in study design and setting may go some way to explain this, this is plausible:
we know that Acinetobacter is shed in high quantities and has
exceptional survival properties.
In the previous post, we reiterated the need to redouble our efforts to tackle contamination of the hospital environment based on these findings, especially at the time of patient discharge, in order to mitigate or even eliminate this increased risk through:
- Improving the cleaning / disinfection process
- Developing new modalities to make cleaning / disinfection easier
- Producing novel disinfectants
- Improved design
- Reduced patient shedding
- Considering antimicrobial surfaces
- Implementing automated room decontamination (ARD)
We now know that being admitted to a room where the previous room occupant had a pathogen is a risk factor for the incoming occupant in acquiring these pathogens, and that improving the quality of terminal cleaning and disinfection mitigates or removes completely this increased risk. So, let's get out there and ensure that all rooms are clean, safe, and ready to deliver the highest quality of care to our patients.
*Only one of the studies included C. difficile, which was performed in an outbreak setting - we would expect future studies to show a higher increased risk for acquiring C. difficile from the prior room occupant!