In 2023, German scientists discovered that dish sponges are the dirtiest item in the kitchen. Every square centimeter of this accessory is teeming with 45 billion bacteria, including pathogens. Now a team of scientists from Northwestern University (USA) has discovered the dirtiest items in the bathroom – they turned out to be toothbrushes and shower heads. The results of the study, published in the journal Frontiers in Microbiomes, identified 616 viruses in 92 samples from shower heads and 34 samples from toothbrushes. The detected microorganisms are bacteriophages or “phages” – types of viruses that infect bacteria and multiply inside them. Most of these viruses have not been found anywhere before.
Shower heads and toothbrushes are home to entire collections of viruses, most of which scientists have learned about for the first time. Image: everydayhealth.com
Contents
- 1 Household bacteria and viruses
- 2 Where do viruses and bacteria live?
- 2.1 Phages and mycobacteriophages
- 3 What to do?
Household bacteria and viruses
It is believed that we spend about 93% of our time indoors, 70% of which is in our homes (including the kitchen, toilet, and bathroom). Since our health is closely linked to the environment and the microbes that inhabit it, researchers have long focused on fungi and bacteria. But viruses have remained unnoticed all these years.
Previously, researchers have described bacteria living on toothbrushes and have proven that these microorganisms are the main cause of contamination that occurs through the oral cavity, the environment, hands and storage containers. The new work is a logical continuation of previous studies.
Hundreds of bacteria and viruses found on toothbrushes and shower heads. Image: zeve.au
Since microbes find it difficult to live on surfaces such as tables and walls, they prefer an environment with water. Therefore, the bathroom and kitchen are perfect for them. The discovered microworld turned out to be even more surprising for scientists than one might have expected. The fact is that most of the microorganisms identified in the new study are bacteriophages.
Read also: Where do microbes live in the house and how to fight them?
Recall that bacteriophages that infect bacteria are capable of changing the structure and functions of microbial communities through horizontal gene transfer. Their role in natural ecosystems has been well studied, but in the context of the home environment, phages remain a mystery. As a rule, bacteriophages do not pose a direct threat to humans. However, they can contribute to the resistance of some bacteria to antibiotics, since they affect the presence of pathogenic bacteria.
Where do viruses and bacteria live?
In the study, the scientists focused on two household items in the bathroom: shower heads and toothbrushes. The latter constantly interact with humans and the environment. Shower heads (like toothbrushes) are also exposed to factors such as temperature changes, humidity, and exposure to hygiene products.
Having collected 92 samples of genetic material from shower heads and 34 from toothbrushes, the team used metagenomic analysis to identify the viruses present on the objects and their possible bacterial hosts. As a result, the scientists identified 616 viral units, many of which had little in common with known viruses, and a significant part of their genome was observed for the first time.
Your bathroom is home to many viruses unknown to science. Image: d.newsweek.com
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Of the 32 bacterial families, only three were present on both toothbrushes and shower heads (Sphingomonadaceae, Burkholderiaceae, and Caulobacteraceae). The team therefore concluded that microbial communities depend on the specific environment: the more bacteria there are in an environment, the more viruses can be detected.
We found many viruses that science knows little about, as well as viruses that we’ve never seen before. Every shower head and every toothbrush is like its own little island, highlighting the incredible diversity of microorganisms that exist,” said lead author Erica M. Hartmann.
Phages and mycobacteriophages
After analyzing the samples, the research team found more mycobacteriophages than other types of phages. Mycobacteriophages infect mycobacteria, pathogenic species that cause diseases such as leprosy, tuberculosis, and chronic lung infections.
Viruses and bacteria are all around us. Image: gizmodo.com
In the future, Hartmann suggested, scientists could use mycobacteriophages to treat a variety of infections. They could also be used to cleanse water systems of pathogens. For now, however, these microorganisms need to be studied in detail to better understand their role in the home microbiome and their potential impact on human health.
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What to do?
So, should you be afraid of viruses that live on household items in the bathroom? Although most microbes do not cause diseases, shower heads should be cleaned regularly, and toothbrushes should be changed every three months. Moreover, it is enough to wash shower heads with ordinary soap.
Also, do not forget that excessive use of antiseptics disrupts the natural balance of microbes. This, in the long term, is fraught with serious health problems.
Overuse of disinfectants can cause serious health problems. Image: henryford.com
Understanding how viruses and bacteria interact in the home could also have practical applications. Bacteriophages, for example, are being considered as a potential alternative to antibiotics in the fight against bacterial infections, and studying them in our natural environments could speed up the development of new therapeutics. What’s more, knowledge of the home microbiome could influence cleaning and hygiene recommendations.
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The results of a research team from Northwestern University open the door to a little-known world of viruses living right under our noses: amazingly, the most common household items are home to entire microbial ecosystems that can affect health. So the next time you brush your teeth or take a shower, remember: you are interacting with an invisible and complex world about which science knows almost nothing.