Many infections live on showerheads and toothbrushes

 Many infections live on showerheads and toothbrushes

No two showerheads or toothbrush bristles are identical, as researchers in the US have discovered a vibrant and diverse world of viruses thriving in biofilms on bathroom surfaces across the US and Europe. While hot showers are enjoyable, you're not the only one enjoying the warm water—new findings reveal that various viral communities inhabit your showerhead as well, and that's actually good news.

"The number of viruses we found is absolutely astounding," said Erica Hartmann, a microbiologist at Northwestern University and lead author of the study. "We identified many viruses we know little about and several that are completely new to science. It's incredible how much untapped biodiversity exists around us, and you don't have to look far to find it—it's right in our bathrooms."

Viruses are typically associated with the diseases they can cause in humans and animals, but not all are harmful; many serve beneficial roles in science. The majority of the viruses identified by Hartmann's team are bacteriophages, which specifically infect bacteria rather than posing a threat to human health.

In their recently published study in Frontiers in Microbiomes, Hartmann's team noted that most Americans spend about two-thirds of their lives at home, making it important to understand the organisms present in these shared spaces.

To analyze the viral communities, the researchers utilized data from citizen science projects that swabbed showerheads and toothbrushes in homes across the US. Their findings revealed distinct microbial communities on each surface, indicating significant diversity.

Typically thought of as existing in a sort of limbo—requiring a host to reproduce and sometimes causing harm—viruses actually thrive in various complex environments. In American bathrooms, Hartmann’s team identified over 600 unique viral species residing on showerheads and toothbrush bristles, with no two showerhead communities being the same.

The research suggests that these bacteriophage viruses could open new avenues for treating bacterial infections and offer alternative ways to clean environments without resorting to antimicrobial products. "The more you use disinfectants, the more bacteria may develop resistance," Hartmann cautioned. "We should embrace microbes; the vast majority are harmless."

The study also aligns with previous research efforts that explored the presence of bacteria and fungi in bathroom environments. Three years ago, Hartmann’s group initiated "Operation Pottymouth" to investigate the claim that flushing a toilet aerosolizes fecal matter onto toothbrushes. They concluded that most bacteria on toothbrushes come from the user’s mouth rather than the toilet.

In 2018, findings from the Showerhead Microbiome Project linked mycobacterium-infected showerheads to lung infections in both American and European bathrooms. Fortunately, Hartmann's latest research found that the bacteriophages commonly identified tend to target harmful mycobacteria. "We could envision using these mycobacteriophages to eliminate pathogens from plumbing systems," she said. "Our goal is to explore all the functions these viruses might have and determine how we can leverage them."