#Microbiotiful - A toothbrush

Staphylococcus aureus, a spherical pathogen that forms grape-like cell clusters, is regularly found on toothbrushes. This species is a major worldwide cause of food poisoning and infections, particularly among people with a weakened immune system. In a recent study, researchers from Daejeon (Korea) calculated that the S. aureus bacteria on month-old toothbrushes proliferate between 5- and 15-fold per additional month of use. To kill off the germs, they suggest soaking the toothbrush either in a 1% antimicrobial mouth rinse solution for 5 minutes or a 1% vinegar solution for 1 minute after each use. If you’re in good health, you may instead just want to get a new toothbrush every now and then.

Ever wondered what causes the characteristic earthy smell of soil? Open a Petri dish in which certain Actinomyces have been growing and you’ll know: it’s the odorous substances they produce. Although bacteria, Actinomyces create a mycelium of branching, thread-like hyphae typical of fungi, for which they were originally mistaken (hence their name). Actinomyces are multitalented—they are also part of the microbiota of humans and colonize your toothbrush. In rare cases they cause infections and form painful abscesses in the mouth. 

Several million bacteria are typically attached to the toothbrushes we use, and Micrococcus species feature in great numbers. In fact, they’re basically on all our household objects, from furniture to light switches to the cutlery waiting to go into the dishwasher. No prizes for guessing how they get there—we spread them ourselves. Micrococci form a major part of our skin’s natural microflora. Luckily they rarely cause us problems, with the possible exception of converting components of the sweat on our bodies and in our clothes into something awfully smelly.

It’s hardly surprising to find Streptococcus species on a toothbrush—S. mutans and S. sobrinus are two of the bacteria associated the most with dental decay, and the more of these you have in your mouth, the likelier you are to develop cavities in your teeth. They attach to dental enamel, produce a biofilm (called plaque) and go about fermenting sugar into lactic acid. The acidity they create attacks your teeth and sets you on course for caries. There’s little point in trying to banish streptococci from your toothbrush—you probably accommodate a whole lot more in your mouth. The best thing to do is to keep brushing your teeth properly and regularly.