Background: Toilet facilities in healthcare settings vary widely, but patient toilets are commonly shared and do not have lids. When a toilet is flushed without the lid closed, aerosol production may lead to surface contamination within the toilet environment.

Aim: To substantiate the risks of airborne dissemination of C. difficile following flushing a toilet, in particular when lids are not fitted.

Methods: We performed in-situ testing, using faecal suspensions of C. difficile to simulate the bacterial burden found during disease, to measure C. difficile aerosolization. We also measured the extent of splashing occurring during flushing of two different toilet types commonly used in hospitals.

Findings: C. difficile was recoverable from air sampled at heights up to 25 cm above the toilet seat. The highest numbers of C. difficile were recovered from air sampled immediately following flushing, and then declined 8-fold after 60 min and a further 3-fold after 90 min. Surface contamination with C. difficile occurred within 90 min after flushing, demonstrating that relatively large droplets are released which then contaminate the immediate environment. The mean numbers of droplets emitted upon flushing by the lidless toilets in clinical areas were 15-47, depending on design. C. difficile aerosolization and surrounding environmental contamination occur when a lidless toilet is flushed.

Conclusion: Lidless conventional toilets increase the risk of C. difficile environmental contamination, and we suggest that their use is discouraged, particularly in settings where CDI is common.