The bad news first: shower heads and toothbrushes in an average bathroom are teeming with an extremely diverse collection of viruses, most of which have never been seen before, a new study finds.

Now, the good news.

These viruses target bacteria, not people, and could provide a new means of confronting the rise in antibiotic-resistant germs, researchers report.

These microorganisms are bacteriophage, or “phage,” a type of virus that infects bacteria, researchers explained.

Phage have recently garnered attention for their potential use in fighting bacteria that have developed resistance to common antibiotics, researchers noted.

“The number of viruses that we found is absolutely wild,” said lead researcher Erica Hartmann, an associate professor of civil and environmental engineering with Northwestern University in Chicago.

 “We found many viruses that we know very little about and many others that we have never seen before,” Hartmann added in a Northwestern news release. “It’s amazing how much untapped biodiversity is all around us. And you don’t even have to go far to find it; it’s right under our noses.”

For the study, researchers analyzed used toothbrushes and sample swabs taken from shower heads, to see what sort of germs might be present.

“This project started as a curiosity,” Hartmann said. “We wanted to know what microbes are living in our homes. If you think about indoor environments, surfaces like tables and walls are really difficult for microbes to live on. Microbes prefer environments with water. And where is there water? Inside our shower heads and on our toothbrushes.”

DNA sequencing showed that the samples contained more than 600 different viruses, and no two samples were alike.

“We saw basically no overlap in virus types between shower heads and toothbrushes,” Hartmann said. “We also saw very little overlap between any two samples at all. Each shower head and each toothbrush is like its own little island. It just underscores the incredible diversity of viruses out there.”

The samples did contain more mycobacteriophage than other types of phage, researchers noted.

Mycobacteriophage infect mycobacteria, a bacterial species that causes diseases like leprosy, tuberculosis and chronic lung infections. Thus, these viruses show promise in attacking bacteria that are dangerous to humans, researchers said.

“We could envision taking these mycobacteriophage and using them as a way to clean pathogens out of your plumbing system,” Hartmann said. “We want to look at all the functions these viruses might have and figure out how we can use them.”

The new study was published Oct. 9 in the journal Frontiers in Microbiomes.

In the meantime, people shouldn’t fret about the invisible swarms of germs living in bathrooms, Hartmann said

Folks who are particularly squeamish can soak their shower heads in vinegar to remove calcium buildup, or simply wash them with plain soap and water, Hartmann said. Don’t use bleach to try and wipe the germs out.

People also should regularly replace toothbrush heads as a matter of course. Choose a regular toothbrush, Hartmann said, and not an antimicrobial brush — those can increase antibiotic resistance among germs.

“Microbes are everywhere, and the vast majority of them will not make us sick,” she said. “The more you attack them with disinfectants, the more they are likely to develop resistance or become more difficult to treat. We should all just embrace them.”

More information

The U.S. Centers for Disease Control and Prevention have more on antimicrobial resistance.

SOURCE: Northwestern University, news release, Oct. 9, 2024

Source: HealthDay