Dangerous fungi in most dishwashers

By Michael Smith (Veshengro)

dishwasher Scientists have found a possibly harmful fungus that grows in dishwashers, surviving high temperatures, aggressive doses of detergents and rinsing salts and both acid and alkaline types of water.

A black yeast called Exophiala dermatitidis was found with a cousin fungus, E. phaeomuriformis, in samples taken from dishwashers in 189 homes in 101 cities in six continents.

Fifty-six percent of the dishwashers contained the fungi on the rubber seal on the appliance door and both species “are known to be able to cause systemic disease in humans and frequently colonize the lungs of patients with cystic fibrosis,” says the study.

The fungi are “extremophile” organisms that are rarely encountered in nature. This suggests they have found an evolutionary benefit by occupying a household niche, thriving on warmth and moisture.

The study appears in the latest edition of the journal Fungal Biology, published by the British Mycological Society.

The probe did not focus on whether the dishwasher fungi had been any threat to health and it says, though, “further search is imperative” given the risk of genetic mingling in this unusual environment.

“The co-existence of different genotypes of the same species possibly enables genetic recombination, resulting into new genotypes with unknown pathogenic potential,” says the paper.

Other microscopic species found in the dishwashers were members of the Aspergillus, Candida, Magnusiomyces, Fusarium, Penicillium and Rhodotorula groups.

While those fungi and fungal spores are certainly something to worry about anyone who has any knowledge of commercial dishwashers and their use would not just be worried about fungi.

I have seen those latter things in operation and let me put it this way...

While a domestic dishwasher pulls in new fresh water at each and every cycle commercial dishwashers do not do that. At times the water can be as old as a day or two in some hotel and restaurant kitchens and I would not put it past some places to even go beyond that. I have seen it more than once that water was about thirty-six hours or so old.

Some fungi are the least to worry about in those settings, I am sure, and having seen what happens in some catering establishments is what has turned me off going to many places to eat and even to drink.

Another reason to wash your dishes by hand and avoid places with commercial dishwashers.

© 2011