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These viruses, however, aren't the kind that cause colds, flu, or other illnesses. They are bacteriophages, or phages, which are viruses that specifically target and attack bacteria. Each phage, resembling a tiny tripod, has evolved to hunt down and destroy a particular bacterial species.
“The number of viruses we discovered is absolutely wild,” said Erica Hartmann, an associate professor at Northwestern University’s McCormick School of Engineering, who led the study. “We found many viruses we know very little about, and many others we've never seen before. It’s amazing how much untapped biodiversity surrounds us.”
The researchers identified over 600 viruses from samples collected from showerheads and toothbrushes. They studied biofilms—communities of microorganisms attached to surfaces—from 34 toothbrushes and 92 showerheads. These samples were originally gathered during a previous study that examined the types of bacteria living on these everyday items.
“One of the things we’re now able to do is not only identify the bacteria in these samples, but also the bacteriophages present,” Hartmann explained in an interview with CNN.
Bacteriophages are already being explored in clinical trials as a potential weapon against antibiotic-resistant bacteria, or "superbugs." By infecting and replicating within a bacterial host, phages could kill harmful pathogens and offer an alternative to traditional antibiotics.
“There’s interest in developing more targeted treatments," Hartmann said. "Instead of using broad-spectrum antibiotics that wipe out your entire microbiome, you could take a drug that only targets the harmful bacteria, leaving the rest of your microbiome intact."
In the U.S. alone, more than 2.8 million antimicrobial-resistant infections occur each year. The World Health Organization has identified antibiotic resistance as one of the most significant global health threats, as it could make routine medical procedures, such as surgery and chemotherapy, far more dangerous.
By sequencing bacterial DNA and analyzing their corresponding phages using advanced computational techniques, researchers gained a deeper understanding of the microorganisms present. Joe Parker, a senior research fellow at the UK’s National Biofilms Innovation Centre who was not involved in the study, noted that this research has provided a wealth of information about these viral ecosystems.
In total, the study identified 614 different viruses. However, Hartmann believes that many more remain undiscovered, as nearly every sample contained a unique mix of microbes.