Assessment of mould remediation in a healthcare setting following extensive flooding

Background: A new hospital building was close to completion when a large pipe carrying clean water broke, causing extensive flooding. Aim: To determine the flood-associated fungal risk to susceptible patients who would use that building. Methods: Though standard flood remediation by the builders was relatively straightforward, there was no model for specialist assessment of patient risk due to the flood-associated mould growth. As levels of background airborne fungal spores can be expected to vary significantly over time, we could not use absolute levels to indicate either an excess of airborne fungal spores or successful remediation. Therefore it was decided to use weekly settle plates, exposed at the same time in flooded (test) and equivalent non-flooded (control) areas to compensate for variations in background levels. Flood-related risk was estimated by the ratio between fungal colonies on the test and control sets of settle plates, rather than absolute number. Findings: Whereas the physical flood remediation, including the use of 'anti-fungal' treatments, was completed in three weeks post flooding, fungal contamination in flooded areas took 38 weeks to return to control levels and remained so for a further six weeks of observation. Conclusion: By the use of this method, we were able to assure the absence of floodassociated fungal risk to susceptible patients who would use that building. We recommend that infection prevention and control teams consider using this approach should they be faced with similar situations. (c) 2024 Published by Elsevier Ltd on behalf of The Healthcare Infection Society.