Kitchen sponges host more germs than other places in the house including toilets, findings of a new study published in the journal Scientific Reports have revealed.

Disease-Causing Bacteria In Used Kitchen Sponge

A sugar-cube sized kitchen sponge can host 54 billion bacterial cells. Study researcher Markus Egert, a microbiologist at the University of Furtwangen in Germany, and colleagues also found that five of the 10 most common types of bacteria found in samples of used sponges they analyzed had pathogenic potentials, which means that there is a likelihood that they can cause disease in humans.

Cleaning Sponges Not As Effective As Previously Thought

The researchers likewise discovered evidence suggesting that cleaning sponges may be less effective than earlier thought.

While microwaving and boiling sponges have been shown to reduce the amount of bacteria by 60 percent, these only apply in laboratory settings and not in kitchen sponges. Researchers think that resistant bacteria possibly survive the sanitation process and then rapidly re-colonize.

Cleaning Sponges Can Make Them Dirtier

Another alarming thing researchers found is that cleaning sponges does not only allow pathogens to thrive, but heating the sponges in microwave and rinsing them in hot and soapy water could even make them dirtier. The researchers thus advised against cleaning sponges for a prolonged period of time.

"Our data showed that regularly sanitized sponges (as indicated by their users) did not contain less bacteria than uncleaned ones. Moreover, "special cleaning" even increased the relative abundance of both the Moraxella- and Chryseobacterium-affiliated OTUs," the researchers wrote in their study.

Moraxella Osloensis

Moraxella osloensis is responsible for the stinky smell in laundry. While it does not commonly cause infections in humans, there have been reports of Moraxella osloensis meningitis.

The researchers said that boiling and microwaving sponges increase the amount of Moraxella likely because the stinky bacteria kill off other better smelling bacteria, which gives Moraxella more room to reproduce.

Using Clean Kitchen Sponges

Experts offer options for cleaner and safer kitchen sponges. It is recommended to replace the sponge frequently regardless if it seems to look OK. The researchers recommend replacing kitchen sponges at least once per week. UK's National Health Service also offered a similar advice.

"Bacteria-laden sponges, if used to wipe down surfaces, could spread pathogenic bacteria around and make infection more likely. You might want to consider simply replacing your sponge regularly, instead of rinsing it in hot water or zapping it in the microwave," the NHS said.

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