High Rates of Pathogenic Fungi Growth Within Household Dishwashers

Fungi Grow in High Numbers Within Household Dishwashers
Household dishwashers are supposed to be cleaning appliances, but they're also breeding grounds for pathogenic species of fungi. Wikimedia Commons

As if worrying about mold in your home's walls wasn't enough, new research has found that these fungi could be lurking in your dishwashers too.

Two studies, one published last week and another published in 2011, found that the high-temperature, moist, alkaline environment in dishwashers was a breeding grounds for fungal species in dishwashers in Europe, Asia, the Middle East, Africa, Australia, and North and South America, Healthline News reported.

Specifically, they found Exophiala (black yeasts), Rhodotorula (red yeasts), and Candida parapsilosis (white yeasts). The 2011 study found that 62 percent of dishwashers tested positive for fungi, with 56 percent of them containing the black yeasts, Exophiala dermatitidis and Exophiala phaeomuriformis. The more recent study also found these fungi present, and their most frequent area of colonization is in the dishwasher door's gaskets.

"The bottom line is that this pathogenic black yeast species occurs rarely in nature, but in very high numbers in the dishwashers," one of the study authors wrote.

Fungi reproduce by releasing spores, which can be inhaled into the lungs where they colonize, causing systemic infections. People taking antibiotics and those with weak immune systems are most at risk. Exophiala fungi are known to infect the lungs of cystic fibrosis patients, and diabetics are prone to skin infections from them.

However, healthy people need not worry.

"We shouldn't overestimate the importance of these organisms relative to what is already in or on your body," Dr. Henry F. Chambers, chief of infectious diseases at San Francisco General Hospital, told HealthDay News in 2011. "There are more fungi - that is, a mold fungus with spores - in an ounce or two of cheese than you're likely to get from exposure to a dishwasher. And, in any case, 99 percent of the organisms that we come into contact with on a daily basis are totally innocuous."

 

Sources: Zalar P, Novak M, de Hoog GS, et al. Dishwashers - a man-made ecological niche accommodating human opportunistic fungal pathogens. Fungal Biology. 2011.

Dogen A, Kaplan E, Oksuz Z, et al. Dishwashers are a major source of human opportunistic yeast-like fungi in indoor environments in Mersin, Turkey. Medical Mycology. 2013.

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