There are certain things that we just expect to be clean in the home. Most of these are associated with cleaning, and the kitchen sponge is probably at the top of the list.

We depend on our kitchen sponge to be clean because we use it to clean the dishes. Unfortunately, Smithsonian is letting us know that kitchen sponges are not only dirty, but they may also have a significant amount of bacteria that even rivals many Petri dishes.

Photo: flickr/Alabama Extension

When you stop to think about it, sponges really have everything that is necessary to grow bacteria.

First of all, they have food particles from the dishes they clean and secondly, they have moisture. It opens up the possibility of breeding all types of bacteria.

In order to look at it further, Duke University studied E. coli. In particular, they looked at 80 strains of E. coli in an effort to see how they would react under different conditions.

Photo: Raw Pixel

Some E. coli will play nicely with other bacteria but there are also some that prefer isolation. The takeaway? The porous nature of a kitchen sponge provides the perfect environment for different types of E. coli.

Researchers took plates from the kitchen and then applied a kitchen sponge in order to see what grew. Not only did it grow solitary E. coli, but it also grew a variety of bacteria that included populations that played well together and those that preferred isolation.

Photo: flickr/Aaron Harmon

Understanding this should not make you stop using the kitchen sponge altogether. What it should do, however, is help you realize that sponges need to be swapped out on a regular basis.

You can also clean your sponges regularly following the USDA’s guidelines for in the microwave or a bleach bath.