We are attached to our mobile phones and they have constant skin contact with us and therefore also with our closest housemates. Smartphones therefore reflect the microbiome of their owners quite reliably. The bacteria on the display even match those on the thumb or index finger 22 per cent of the time - although the microbial population between two fingers of a person only matches 32 per cent of the time. For the most common hand bacteria such as streptococci and staphylococci, the patterns even match 82 per cent. This means that the owners and their smartphones can be matched to each other based on this microbiological fingerprint - even better for women than for men.

 

Every smartphone tells the story of its user, where they have been or what they have touched. A fleeting touch of our olfactory organ is enough to transfer the typical nasal bacterium Staphylococcus aureus to the smartphone when typing. Harmless soil bacteria such as Bacillus mycoides indicate that the mobile phone user was probably out and about in the woods beforehand.

WhatsApp from the loo? Among 18 to 29-year-olds, 78 per cent use their mobile phones or smartphones. While washing hands is more or less routine for most people, the mobile phone goes back into the bag uncleaned. Mobile phones carry ten times more bacteria than most toilet seats.

 

However, the all-clear can be given for our normal use of mobile phones. Smartphone touchscreens are only moderately contaminated with microorganisms. Most users probably wipe their display regularly - if only to remove annoying fingerprints. In addition to conscientious hand washing, regular cleaning of the mobile phone surface with alcohol-based glasses or microfibre cloths also helps.