Several new studies have found the kitchen to be room in the house most contaminated with bacteria, owing mainly to the microbes present in the common kitchen sponge. Sponges provides an ideal environment for bacterial incubation and can spread these bacteria throughout the room simply by coming in contact with other surfaces. Consumers may be wondering how these bacteria are able to survive so well, and what can they do to rid their sponges of contaminants?
These microbes’ genetic information can be altered to help them adapt to a variety of environmental pressures, including domestic environments. Constructed environments (including homes, offices, or any manmade structure) “harbor a huge variety of microhabitats that are colonized by a wealth of microbial species, which occupied, or evolved to adapt to, the available niches, according to one study on bacteria in sponges.”
Bathrooms and kitchens are the two domestic environments with the most potential to harbor bacteria. These function as “microbial incubators” because of the continual introduction of new bacteria and microbial cells, often through handling food products or by direct physical contact with surfaces throughout these rooms. In order for bacteria to successfully grow in these environments, there must be a few key elements present, such as humidity and readily available nutrients. With all of these factors taken into consideration, the kitchen was found to host more microbes than toilets, mainly because of kitchen sponges.
One study stated that, “Fecal coliforms were found in 44% of homes (most often in samples from kitchen sinks, sponges, and dishcloths), and E. coli was found in 15% of homes (mostly in samples from kitchen sinks). Nearly half (45%) of the homes tested positive for a foodborne pathogen, and 12% had multiple pathogens present in the kitchen. S. aureus was isolated from 39% of homes, most often from countertops and refrigerator door handles.” The study concluded that the contamination of a sponge with these bacteria would often result in the contamination of the rest of the kitchen, indicating that the sponge is a bacterial reservoir and vector.
Another study found that kitchen sponges “were proven to represent the biggest reservoirs of active bacteria in the whole house … Further works [also] showed the presence of specific pathogenic bacteria in [some] kitchen sponges, including Campylobacter spp., Enterobacter cloacae, Escherichia coli, Klebsiella spp, Proteus spp., Salmonella spp., and Staphylococcus spp.” These bacteria are known to cause food poisoning, various infections, boils and painful rashes, and bloodstream infections.
In order to visualize this level and concentration of bacteria, NPR’s Michaeleen Doucleff said, “Forty-five billion microbes per square centimeter? Are you kidding? If you scale that up, that’s like stuffing all the people who live in Manhattan into the Rockefeller ice rink.”
Thankfully, despite some recent headlines, the United States Department of Agriculture (USDA) found that “microwaving sponges killed 99.99999 percent of bacteria present on them, while dishwashing killed 99.9998 percent of bacteria.” A few additional suggestions to ensure sponge cleanliness, made by Professor Quinlan of Drexel University during an interview with NPR, are:
Keep the sponge away from raw meat. “If you’re dealing with raw juices from meat or poultry, you should be using paper that can be disposed of,” Quinlan says.
Don’t keep sponges around for too long. “I replace mine every one to two weeks,” she says. “That’s reasonable to me.”