Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


The Kitchen Sponge – Breeding Ground for Germs


The first comprehensive study of contamination in used kitchen sponges worldwide has just been published. The high concentration of bacteria found in these cleaning materials is partially cause for concern. Washing the sponge in hot water or putting it in the microwave is not a long-term solution, say the researchers.

In Germany there are around 40 million private households. “If each has one or two kitchen sponges then the total number is around 40 to 80 million,” says Professor Dr. Markus Egert of Furtwangen University who headed up the study. “If you include institutional facilities, you are probably talking about more than 100 million in Germany.” One hundred million potential germ breeders.

Analysis of bacteria in sponge sample. Maximum projections of confocal stacks, showing EUB338MIX–stained bacteria in red (A and E) and sponge autofluorescence in cyan (B and F)

Scientific Reports

The study was a cooperative project between Furtwangen University (HFU), the Justus Liebig University in Gießen and the Helmholtz Centre in Munich; HFU funded the project. The study has now been published in the prestigious scientific journal “Scientific Reports” which belongs to the Nature Publishing Group. (DOI:10.1038/s41598-017-06055-9 1,, Title: Microbiome analysis and confocal microscopy of used kitchen sponges reveal massive colonization by Acinetobacter, Moraxella and Chryseobacterium species).

The microbiologists put 14 used sponges from the Villingen-Schenningen area under the microscope. They found 362 different types of bacteria. “What surprised us was that five of the ten which we most commonly found, belong to the so-called risk group 2, which means they are potential pathogens,” explained Egert.

These are environmental and water bacteria, but also bacteria which are typical for the human skin. Particularly for people with a weak immune system such as patients and the elderly, bacteria such as Acinetobacter johnsonii, Moraxella osoloensis and Chryseobacterium hominis can lead to infections. The very commonly found Moraxella osloensis bacteria can also cause kitchen sponges to stink. Faecal bacteria and those which cause food poisoning or dysentery however, were scarcely detected.

However the real cause for concern is: in sponges which according to their users were regularly cleaned either in the microwave or through washing, showed considerably higher levels of potentially pathogenic bacteria. The scientists assume that the cleaning of the sponges can lead to a short-term decrease in the number of germs; obviously in the quickly regrowing communities however, the potentially pathogenic bacteria achieve an ever stronger domination, probably due to a higher stress tolerance.

Kitchen sponges are mainly made of foam material, such as polyurethane. Due to their multiple pores, the huge inner surface area offers microorganisms a lot of space to grow. “Sometimes the bacteria achieved a concentration of more than 5 times 1010 cells per cubic centimetre,” explained Egert. “Those are concentrations which one would normally only find in faecal samples.

And levels which should never be reached in a kitchen. These high concentrations can be explained by the optimal conditions the bacteria find in the sponge: besides the large surface area for growth, there are high levels of moisture and nutrients from food residue and dirt. The photographic and film material from the study is impressive proof of the bacterial contamination of the kitchen sponges and can thus be used as teaching material to raise awareness for kitchen sponges as microbial incubators in the household.

Problems can arise particularly in sensitive environments - in hospitals, retirement homes or in private houses, if patients with weak immune systems are nursed at home. Instead of frequent washing, for hygienic reasons it is better to throw kitchen sponges away regularly, approximately once a week. Incidentally, the researchers could not detect any microbial contamination in newly bought sponges.

Weitere Informationen:

Jutta Neumann | idw - Informationsdienst Wissenschaft
Further information:

More articles from Life Sciences:

nachricht More genes are active in high-performance maize
19.01.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht How plants see light
19.01.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>



Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

More VideoLinks >>>