Moulds in Drinking Water

The main focus on fungal contamination within healthcare facilities is directed at air quality and ventilation, however a relatively common source is in-premise water networks.  Fungi can become part of the water pipework biofilm, with spores and hyphal fragments released into the water flow and eventually dispersed via water outlets into the environs and onto users.  Inhalation and aspiration routes of transmission can lead to lung infections. Direct contact can lead to skin and mucous membrane infections.

Site renovation and construction is often a trigger for increased contamination rates, with consideration that the dust generated may be distributing fungi liberally in surrounding areas.  Renovation and construction often cause unusual activity within plumbing networks – jiggling of pipes, hammering effects etc – which can lead to dispersal of higher than normal levels of spores and fragments downstream.

Fungal infections are very hard to treat.  Patient groups who are known to be at risk include neutropenic patients, transplant recipients, individuals with cystic fibrosis and other lung disorders.  There is very limited guidance surrounding the prevention or reduction of fungal exposure from water, although, where known problems exist, it is common to see high risk patients receiving sterile water, 0.2 micron sterilising grade filtered water, and where practicable such patients are placed some distance away from any water outlets.

During August there were three interesting publications relating to the incidence of moulds in drinking water.  The first, from Babič & Gunde-Cimerman, reported on a comparison of culturable fungi occupying Swedish and Slovenian habitat drinking waters.  Sweden does have a published fungal limit of 100 CFU/100 mL in drinking water, although there are no specific regulations in other countries with “no pathogens” often used as a cover-all for guidance.  Within private domestic homes, fungi were isolated from 75% of Swedish water and 90% of Slovenian water samples.  Levels of fungi per sample were within the limits set in the Swedish guidance.  The main species of fungi found were different (see table below) which would be expected due to the different geographical locations, raw water sources and water treatment methods.

Swedish Drinking Water SamplesSlovenian Drinking Water Samples
Varicosporellopsis (27%)Aspergillus (46%)
Paracremonium (14%)Aureobasidium melanogenum (36%)
Black yeasts (mainly Cadophora, Cyphellophora, Exophiala) (18%)Exophiala (24%)

Fungi with known negative effects on health (Aspergillus fumigatus, Candida parapsilosis sensu stricto, Exophiala phaeomuriformis, Bisifusarium dimerum, and Rhodotorula mucilaginosa) were isolated within the drinking waters of both studies and represent fungal species that are listed by the World Health Organisation as emerging pathogens. Will this study engage those healthcare facilities struggling with fungal infections to look into their water sources and protect vulnerable patients from drinking water sources?  This study certainly highlights the importance of recognising the presence of emerging fungi in drinking water – it is definitely not all in the air.

Mohorea et al., published on an invasive fusariosis outbreak in a group of haematology patients from an acute leukaemia ward.  The outbreak involved 12 cases within a short 2 month period in 2018, followed by 4 separate cases which continued sporadically until 2021.  Patient diagnosis was based on blood samples and tissue biopsy.  Environmental surveillance found both indoor air and water installations to be contaminated with Fusarium spp.  Once the water installation had been replaced, the number of patient cases dropped dramatically to a background baseline infection level of one or two cases per year.

Severely neutropenic patients were most critically affected in this outbreak, suffering with respiratory involvement (lung lesions), skin lesions and severe myalgia.  Mortality rates were highest in this group.  Should water sources be in haematological patient areas at all? If water sources are present, invasive fungal species must be constantly controlled – not only from the air but also water – for this highly immunocompromised group.

The third publication is from a well published Canadian team, Cazals et al., whose subject matter focuses on how unhygienic ice and ice machines are.  Despite several links to outbreaks and pseudo-outbreaks, there is little dedicated or validated ice machine maintenance or service, nor protocol driven and audited cleaning.  In the UK ice machines can still be found in healthcare facilities, although most are no longer used for direct patient contact due to their significant hygienic risk.

In Cazals’ study, 36 ice-water machines within a 772 bed hospital were tested for heterotrophic plate count (HPC), faecal indicators (Enterococci) and opportunistic pathogens which included Pseudomonas aeruginosa, non-tuberculous mycobacteria and Candida spp (fungus).  Adjacent taps were also sampled at some ice machine locations.

Non-tuberculous mycobacteria (NTM) were found in all samples with Candida spp. found in more than half the ice-water samples.  Enterococci and Pseudomonas aeruginosa were identified in 55% of drain inlets.  NTM was found at higher levels within the ice machine water, even post flushing, than in the adjacent flushed tap water.  Pre-filters, particularly carbon filters, were found to be an additional amplification site for microorganisms.  If an ice machine is installed within your healthcare facility, please consider the routes that this ice (or chilled water) takes to the patient and whether there is a less hazardous option that can be adopted to reduce the risk of infection.  If you have a regular cleaning and disinfection protocol in place, please ensure that it is validated, verified and that operational monitoring is completed regularly to assure ice and water quality as well as drain hygiene.

If you have any concerns regarding fungal contamination of your water, or if you have ice machines onsite which would benefit from additional assessment, please do not hesitate to discuss with the Harper Water Team.

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Babič MN, Gunde-Cimerman N. Culturable mycobiota of drinking water in Göteborg (Sweden) in comparison to Ljubljana (Slovenia) with implications on human health. J Water Health. 2023 Aug;21(8):1064-1072. doi: 10.2166/wh.2023.089. PMID: 37632381.

Mohorea-Neata AL, Ghita MC, Moroti R, Ghiaur A, Ionescu B, Tatic A, Stancioaica MC, Bardas A, Al-Hatmi A, Coriu D. Invasive fusariosis in acute leukaemia patients-An outbreak in the haematology ward. Mycoses. 2023 Aug;66(8):705-710. doi: 10.1111/myc.13596. Epub 2023 May 2. PMID: 37128958.

Cazals M, Bédard E, Soucy C, Savard P, Prévost M. How clean is your ice machine ? Revealing microbial amplification and presence of opportunistic pathogens in hospital ice-water machines. J Hosp Infect. 2023 Aug 19:S0195-6701(23)00270-0. doi: 10.1016/j.jhin.2023.08.007. Epub ahead of print. PMID: 37604277.

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