Your energy-efficient washing machine could be harbouring germs

Energy-efficient machines save energy and money by washing clothes at cooler temperatures, but are they inadvertently harbouring germs?

Recent research published in the journal Applied and Environmental Microbiology identified a worrying situation in a German neonatal ward. One of the washing machines used to wash the knitted caps and socks for the babies was a household machine, which washed the clothes at a lower temperature than the standard hospital machine.

It was found that this machine transmitted the bacteria Klebsiella oxytoca repeatedly to the newborns. The bacteria were found in the detergent drawer and on the rubber door seal of the domestic washing machine, used in the same ward to wash the laundry of the newborns.  Luckily none of the babies was infected. 

Usually, K. oxytoca is a healthy gut bacteria, which is also found in the mouth and nose. But outside the body, this antibiotic-resistant bacteria can cause serious infections. These include pneumonia-like symptoms, wound and urinary tract infections.

However, microbiologist Dr Chau Le, from the University of Sydney, says the possibility of a healthy person catching a bacterial infection from clothing at home was slight, even using a cold wash.

“At home, if they are using a detergent, which people do when they are using the washing machine, that’s strong enough to get rid of the bacteria”, she says.

While washing powder or liquid doesn’t make clothing sterile, they do kill most of the bacteria found on them.

“The way detergents work is they break down fats and enzymes. That helps to breakdown certain food stains. Bacteria are made of a cell wall, and their membrane is made of fats. So, by applying the detergent, you are going to disrupt their cell wall and cause it to break open, or lyse, and that will kill the bacteria,” says Dr Le.

However, with newborn baby clothes or bandages, there are some precautions you could take in the home to prevent infection.

“If they were worried, they could make the water warmer, to 35-37 degrees Celsius. You could add a kind of bleach to your washing as well. That has an antimicrobial effect. Probably more importantly, after washing your clothes or your bandages, not hanging them on the line outside. There is dust and pollen in the air and a whole bunch of other things that could land on that bandage,” says Dr Le.

“Minimising cross-contamination between soiled clothes and bandages by rinsing the clothes first, or, being extra safe and washing the clothes separately. That would be a good measure to take,” she says.

Also drying the bandages or clothes in the dryer at hot temperatures should kill any other microbes lurking in the fabric.

“Given that you cycle for about 30 minutes, at a high concentration of washing powder, it is likely that you are going to kill most of those bacterial cells in this process. There are some exceptions. Some bacteria resist the detergent and [could] still be around after you wash your clothes. But they are not necessarily going to cause you any harm,” says Dr Chau.