Ask Dr. Nandi: Your washer might be breeding drug-resistant germs

Your washer might be breeding drug-resistant germs
Posted at 9:56 PM, Oct 07, 2019
and last updated 2019-10-07 21:56:50-04

Is your washing machine a reservoir for ‘superbug” bacteria? They just might be. This warning follows an investigation of a consumer-grade washing machine at a hospital in Germany - where pathogens were being transmitted to newborns.

Question: Tell us about the bacteria.

The drug-resistant pathogen is called Klebsiella oxytoca. It’s actually a healthy gut bacteria, but only if it’s inside your gut. If K. oxytoca is on the outside, it can cause serious infections. Now the newborns at the German children’s hospital were in the neonatal intensive care unit. And the investigators linked the energy-efficient washing machines to the outbreak because K. oxytoca was found on knitted caps and socks that were used to keep the babies warm. Now it’s not known how the bacteria got into the washing machine but investigators found it in the detergent drawer and on the rubber door seal. Most likely it was able to live because of the lower heat temperature settings and the fact that the water didn’t drain completely due to the design of the machine.

Question: Wouldn’t the washing machine kill the bacteria?

Well hospitals don’t typically use consumer-grade machines designed for households. Instead they use special high-temperature industrial washing machines that allow disinfectants to be added. So this is very usual. But it does serve as a warning to consumers that it’s possible to have germs live in your machine because energy-efficient ones wash clothes at lower temps, typically around 140 degrees Fahrenheit. So it’s less likely to kill off drug-resistant germs.

Question: Did the bacteria harm the newborns and what sort of threat does it present to most people?

The good news is that 13 newborns were only colonized with K. oxytoca and not infected. That means the bacteria was not a threat. Either because it had not yet invaded susceptible tissue or because the newborn’s immune systems effectively fought it off. But most people who get exposed do not get infections. However this bacteria is an opportunist, so those who need to be the most concerned are the elderly with an open wound or bladder catheter, and young people with pus-like injuries or infections. To help avoid transmission, it’s recommended to wash laundry at very high temperatures with high-quality disinfectants.