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Fungi in water pose great risk to immune-compromised individuals

24 July 2023 | Story André Damons | Photo Supplied

Yeast and other filamentous fungi, which pose a great risk to the health of immune-compromised or suppressed individuals, can be found in various drinking water sources such as ground, spring, surface, and tap water. These opportunistic pathogens may cause severe to fatal infections and can range from superficial to bloodstream or systemic infections.

This is according to Tyla Baker, a postgraduate student in the Department of Microbiology and Biochemistry at the University of the Free State (UFS). She is studying for her MSc degree in Microbiology under the supervision Prof Carlien Pohl-Albertyn, National Research Forum (NRF) SARChI Research Chair in Pathogenic Yeasts. Prof Jacobus Albertyn and Dr Jolly Musoke are her co-supervisors.

Baker says the fungi in the water highlights that current water treatment processes are not efficient in their removal from water destined for household use. “These infections may not be harmful to people with healthy immune systems, but do pose a great risk to the health of immune-compromised or suppressed individuals.

Definite possibility to contract fungal infections from polluted water

“As the number of people with immune systems that are less functional (e.g. premature babies, elderly persons, people with cancer, diabetes or other serious diseases, HIV+ persons, transplant patients) increases, the number of people at risk of fungal infection also increases,” says Baker.

According to Baker, a previous study done in Brazil has identified yeast in bottled mineral water as well as municipally supplied tap water. The potential risk to contract fungal infections from polluted water sources is a definite possibility but more research is required to fully understand and determine the level of risk and the extent of its effects, she says. In the context of Mangaung, it is a concern that untreated water from sewage works as well as other sewage often leaks into the environment (as evidenced by numerous recent articles in local newspapers). These waters are potential carriers of large numbers of pathogens (including pathogenic yeasts/fungi) that may increase the risk to people coming into contact with it.

Baker says there is a good chance people are consuming these kinds of micro-organisms daily, considering that yeast and other filamentous fungi can also form biofilms inside pipes and spread as the impact of water flow dislodges these cells. “People will not even be aware that they are consuming these micro-organisms, some fungi are considered nuisance microbes and may cause a change in the smell and taste of water which may act as an indicator that the water is contaminated, but tests would be needed to confirm this,” she says.

The effects of consuming these fungi are still a grey area of research since the full extent of the consumption of yeast is still unknown, but there are studies being conducted to elucidate the full impact of this occurrence, says Baker. The risk depends on the immune status of the person, the specific species of yeast/fungus ingested, and the number of cells/spores ingested.

Culture-dependent and independent methods

“It is important to know that many pathogenic yeasts and other fungi are opportunistic pathogens, meaning they infect individuals whose immune systems are compromised due to various reasons such as illness (HIV/AIDS, cancer, TB etc.), undergoing organ transplants or even something as simple as using antimicrobial agents such as antibiotics.

“Taking this into account, along with the HIV/AIDS statistics in South Africa, which has a prevalence rate of 13,7% with approximately 8,2 million people in 2021 living with HIV, these individuals are more susceptible to infection by these opportunistic pathogens. Some of these pathogenic yeasts are also multidrug resistant or show resistance to readily available antifungals, such as fluconazole, which hinders the ability of healthcare professionals to efficiently treat infections to avoid fatal/severe outcomes,” explains Baker.

For her studies, she will be testing for fungi in water by using a combination of culture-dependent and independent methods to try and identify yeast present in wastewater. Baker says culture-dependent techniques will include culturing (growing) yeast on an appropriate medium while culture-independent techniques will include more intricate molecular work in the form of a multiplex PCR (polymerase chain reaction) which will enable her to identify an array of pathogenic yeasts present in samples.

According to Baker, people can stay safe by boiling water before drinking it, although temperatures above 100°C are required to kill most harmful microbes. Regular cleaning of shower heads and faucets help to prevent build-up which may act as a surface to which fungi will attach to and grow. Another way to stay safe is to maintain and regularly inspect water filters for damage and avoid contact with untreated sewage.

News Archive

Research by experts published in Nature

2011-06-02

The members of the research group are, from the left, front: Christelle van Rooyen, Mariana Erasmus, Prof. Esta van Heerden; back: Armand Bester and Prof. Derek Litthauer.
Photo: Gerhard Louw

A research article on the work by a team of experts at our university, under the leadership of Prof. Esta van Heerden, and counterparts in Belgium and the USA has been published in the distinguished academic journal Nature today (Thursday, 2 June 2011).

The article – Nematoda from the terrestrial deep subsurface of South Africa – sheds more light on life in the form of a small worm living under extreme conditions in deep hot mines. It was discovered 1,3 km under the surface of the earth in the Beatrix Goldmine close to Welkom and is the first multi-cellular organism that was found so far beneath the surface of the earth. The worm (nematode) was found in between a rock face that is between 3 000 and 12 000 years old.

The research can shed some new light on the possibility of life on other planets, previously considered impossible under extreme conditions. It also expands the possibilities into new areas where new organisms may be found.

These small invertebrates live in terrestrial soil subjected to stress almost for 24 hours They live through sunshine, rain, scorching temperatures and freezing conditions. Through time they developed a means to cope with harsh conditions. Terrestrial nematodes (roundworms, not to be confused or related to earthworms) are among those very tough small invertebrates that deal with those conditions everywhere. After insects they are the most dominant multi-cellular (metazoan) species on the planet having a general size of 0,5 to 1 mm and are among the oldest metazoans on the planet, Nature says in a statement on the article.

They inhabit nearly every imaginable habitat form the deep seas to the acid in pitcher . Some nematodes simply eat bacteria and these are the ones we study here. Terrestrial nematodes have developed a survival stage that can take them through hard times (absence of food, extreme temperatures, too little oxygen, crowding, and more).

At the head of the research was Prof. Gaetan Borgonie of the Ghent University in Belgium and a world leader in the discipline of nematode research. He was brought into contact with the South African research leader, Prof. Esta van Heerden, who set up a cooperation agreement with the University of Ghent and Prof. Borgonie. Prof. Van Heerden manages the Extreme Biochemistry group at the UFS and the research was funded by several research grants.

The search for worms began in earnest in 2007, but it was soon clear that the sampling strategy was insufficient. A massive sampling campaign in 2008-2009 in several mines led to the discovery of several nematodes and the new nematode species Halicephalobus mephisto. It is named after the legend of Faust where the devil, also known as the lord of the underworld is called Mephistopheles.

Nature says special filters had to be designed and installed on various boreholes. Unfortunately, there is no easy way of finding a magic formula and designs had to be adapted by trial and error; improving existing designs all the time. The work of the UFS Mechanical Workshop, which manufactured, adapted and helped design it, was crucial in this respect. Filters were left on the holes for varying periods, sometimes for a few hours and sometimes for months. Prof. Derek Litthauer from the UFS played a big role in sampling, filter designs and coming up with ideas for names for the new nematode with Prof. Borgonie.

Research showed that the nematodes can live in the deep for up to 12 000 years. Three students – Armand Bester, Mariana Erasmus and Christelle van Rooyen from the UFS – did the work on this.

The importance of multi-cellular animals living in the ultra-deep subsurface is twofold: The nematodes graze on the existing bacterial population and influence their turnover. Secondly, if more complex multi-cellular organisms can survive in the deep subsurface on earth, this may be good news when looking for life on other planets where the surface is considered too inhospitable (e.g. Mars). Complex life forms can be found in ecosystems previously thought to be uninhabitable. Nature says this expands the possibilities into new areas where new organisms may be discovered.

Future research will focus on selective boreholes to look for more metazoans, so that a better idea of the complexity of the ecosystems there can be obtained. It will also look for metazoans in the deep subsurface on other continents to determine similarities and differences.

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