Bacillus species pseudo-outbreak: construction works and collateral damage.

We describe the investigation and management of a pseudo-outbreak of Bacillus spp. bacteraemia associated with construction work in an emergency department (ED). During the pseudo-outbreak period 59 out of 3469 (1.7%) blood cultures yielded Bacillus spp. versus 24 out of 7628 (0.31%) in 2012. Material, surfaces, and air samples showed environmental contamination. Cases rapidly declined following the implementation of infection control measures and the end of construction. Construction works at the ED caused environmental contamination that most probably led to the pseudo-outbreak of Bacillus bacteraemia. In hospital settings, the lack of correctly implemented effective barriers during construction may place patients and healthcare providers at risk as well as lead to pseudo-outbreaks.