Electromagnetic radiation is no laughing matter. Microwaves harness this force — a fraction of the sun’s power on Earth’s surface — to heat food from the inside out, vibrating molecules with light. It’s an “extreme environment” that would melt most life. According to a new study, some bacteria have adapted to make a joke of it all the same.

Published in the journal Frontiers in Microbiology, researchers from Spain have discovered certain bacteria survive inside household microwaves — creating a “specialized community” of microbes that leave the interior of the common kitchen appliance no cleaner than your average countertop.

“Some species of genera found in domestic microwaves, such as Klebsiella, Enterococcus and Aeromonas, may pose a risk to human health,” one of the study’s authors, Daniel Torrent, told Frontiers in a news release. “However, it is important to note that the microbial population found in microwaves does not present a unique or increased risk compared to other common kitchen surfaces.”

According to the Atlanta-based Centers for Disease Control and Prevention, klebsiella is a fecal bacteria that can cause pneumonia, bloodstream infections, wound/surgical site infections and meningitis. Some forms of the bacteria are also becoming more resistant to antibiotics.

Enterococcus can lead to infections in the bloodstream and urinary tract, while aeromonases are often found in aquatic environments — though they are also sometimes present in soil, vegetables and food. The microorganisms can colonize and infect people with gastrointestinal tract disorders and possibly lead to septicemia, the body’s “most extreme response to an infection.”

“For both the general public and laboratory personnel, we recommend regularly disinfecting microwaves with a diluted bleach solution or a commercially available disinfectant spray,” Torrent added. “In addition, it is important to wipe down the interior surfaces with a damp cloth after each use to remove any residue and to clean up spills immediately to prevent the growth of bacteria.”


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