Heat, humidity and nutrients. Three essential ingredients for the proliferation of bacteria. The porosity and absorbency of dish sponges make them perfect incubators for massive colonies of bacteria that can affect your health.
53 billion germs per cm²! This is the hallucinatory figure of the study published on July 19 in the journal Scientific Report by a team of German researchers specializing in microbiology. Using state-of-the-art techniques, such as fluorescence and genetic sequencing, these researchers analyzed fourteen used sponges before delivering their findings.
And these are terrifying : « Sponges are the largest reservoirs of active bacteria in the whole house, » says the report. More than their number, it is the nature of these microorganisms that worries researchers. If they discovered about 73 different types of bacteria on a single sponge, 70% of them can be categorized into just 10 distinct families, including 5 potentially pathogenic.
Indeed, the team of microbiologists has identified, thanks to their DNA, enterobacteria – which can cause intestinal infections – and, even more frightening, proteobacteria such as salmonella, responsible for example of typhoid fever, or vibrio, at origin of cholera.
A kitchen sponge, laden with organic material at each wash, is a paradise for microbes of all kinds. It would shelter even as much as human fecal matter! The researchers point out that if one is not careful about changing spongers regularly, these bacteria eventually clump together to spread elsewhere in the house.