A discovery made in a neonatal intensive care unit at a hospital in Germany is rattling owners of household energy-saving washing machines around the world.
It began when multidrug-resistant pathogens kept reappearing on the skin of premature babies. According to a report on the case published by the American Society for Microbiology Friday, investigators struggled to locate the source of the contamination—that is until they began testing the knitted socks and hats given to the babies.
From there they were able to trace the bacteria to the hospital laundry room where, to their surprise, they found not industrial washing machines with high temperatures and disinfectants, but a household energy-saving washing machine.
According to a press release, the Klebsiella oxytoca bacteria were found in the detergent drawer and on the rubber door seal of the washing machine, in addition to two nearby sinks.
As it turns out, the rubber seal and detergent compartment of a household washing machine provides the perfect environment for bacteria to flourish—especially with energy-saving cold and lukewarm water used in many domestic washers.
Northwestern University professor Erica Hartmann, who studies the microbiology of indoor environments but was not involved in the report, told Popular Science that it’s well-known that anywhere there’s water, bacteria can grow. Sinks and drains are two known reservoirs, she says. “[But] do people think about washing machines? No, not typically.”
Though household washing machines of any type are good at removing dirt and stains from clothes, sheets, and towels, they don't sterilize them. Only temperatures above 140°F are sufficient to kill bacteria, and in domestic washing machines, warm water typically falls between 90°F and 110°F, while water between 60°F and 80°F is considered cold.
But that doesn’t mean you need to freak out. Unless you are caring for someone who is immunocompromised in your home, you needn’t worry. Fortunately, our bodies are used to our own germs! That being said, now might not be a bad time to wash your washing machine. Most importantly, keep a close eye on the rubber seal, detergent compartment, and other parts that are prone to dampness and make sure they stay nice and dry between washes.