According to scientists at the University of Pennsylvania School of Dental Medicine (USA), the microbes that cause tooth decay are forming into super-organisms and “crawling” on teeth. These microorganisms, including bacteria and fungi, form dense, structured clusters, become more resistant to antibiotics and are able to move around, “creating limbs for themselves”.
These clusters, found in the saliva of children with severe tooth decay, were found to be stickier and more resistant to antimicrobials than individual bacteria or fungi.
Surprisingly, these clusters are able to suddenly grow ‘limbs’ to help them move around the tooth surface, even though each microbe is immobile on its own. The discovery was made by chance while studying saliva samples from babies, and looking through a microscope, the scientists noticed the movement of these clusters, almost like a new organism with new functions.
The main causes of tooth decay are the bacteria Streptococcus mutans and the fungus Candida albicans. Caries develops when sugar is deposited on the teeth and microorganisms feed on it, forming plaque that erodes the enamel. To study the behaviour of these microbes, the scientists used microscopy technology to observe them in real time. They created a mock-up of tooth enamel and multiplied bacteria and fungi from human saliva in it.
These highly organised structures were found in an extracellular glue-like polymer and proved to be incredibly hardy and even resistant to antibiotics. The most intriguing feature of these clusters turned out to be their mobility, namely their ‘jumping’ and ‘walking’ movements.
Some bacteria used fungal hyphae to move across the surface, allowing them to rapidly colonise new areas and spread caries. The scientists recorded the ‘microbial clusters’ moving at speeds of more than 40 microns per hour, which is comparable to the speed of fibroblasts, cells involved in wound healing. The clusters were even observed ‘jumping’ to distances of more than 100 microns, which is 200 times their own length.
Prepared by Mary Clair
