Fungi in sink drains act as ‘reservoirs for mould’

Sinks and P-traps are home to a surprising number of fungal organisms, according research from the University of Reading.

Five University of Reading undergraduate students, and a PhD student, tested more than 250 restroom sinks for fungi, such as black moulds, and relatives of baker’s yeast. Each of the sinks had a very similar community of yeasts and moulds, showing that sinks in use in public environments share a role as reservoirs of fungal organisms.

The findings are published in Environmental DNA (https://doi.org/10.1002/edn3.375).

Dr Soon Gweon led the project. He said: “We spend 90% of our time indoors so we are exposed to fungi in our homes and workplaces. For most people, this isn’t a problem, but for those who are immunocompromised, certain fungal species can cause serious infections.

“It isn’t a big surprise to find fungi in a warm, wet environment. But sinks and P-traps have thus far been overlooked as potential reservoirs of these micro-organisms. This could be a really important finding for those who are trying to help immunocompromised people avoid infections by some of the opportunistic pathogens that may be lurking in sinks, such as Fusarium.”

The technique the students used to identify organisms gave them the broader families represented. Further studies will look in detail at exactly which species are present and will identify potential disease-causing fungi.

Zoe Withey, the University of Reading PhD student involved in the project, said: “It has been great to give undergraduate students a real-life hands-on experience of environmental microbiology. And the fact that we found interesting results, worthy of a peer-reviewed publication, is an experience that many students won’t have until their PhD studies, or beyond.”

The types of fungi that live in sinks can tolerate high temperatures, low pH (acidic), and low nutrients. Some will even use detergents, found in soap, as a source of carbon-rich food.

There was no difference observed between male and female restrooms. In fact the 250 sinks tested, all had a very similar population of fungi present.

Dr Gweon said: “Although these findings don’t present a health concern in the environment we are in, were the location a hospital or care home, with many immunocompromised people, this finding could point to a serious risk to health.

“We would like to see cleaning protocols developed that can address the colonisation of sinks and P-traps, particularly in environments where many people will use a single sink.”

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