How do biofilms help bacteria?

Although the pathogens that cause acute infection are generally free-floating bacteria – also referred to as planktonic bacteria – those chronic bacterial forms that stick around for decades long ago evolved ways to join together into communities.

Why? Because by doing so, they are better able to combat the cells of our immune system bent upon destroying them.

Biofilms form when bacteria adhere to surfaces in aqueous environments and begin to excrete a slimy, glue-like substance that can anchor them to all kinds of material – such as metals, plastics, soil particles, medical implant materials and, most significantly, human or animal tissue.

Nearly every species of microorganism – including viruses, fungi, and Archaea – have mechanisms by which they can adhere to surfaces and to each other.

Furthermore, it is now understood that biofilms are extremely diverse. For example, upward of 300 different species of bacteria can inhabit the biofilms that form dental plaque .

According to a recent public statement from the National Institutes of Health, more than 65% of all microbial infections are caused by biofilms.

This number might seem high, but according to Kim Lewis of the Department of Chemical and Biological Engineering at Tufts University, “If one recalls that such common infections as urinary tract infections (caused by E. coli and other pathogens), catheter infections (caused by Staphylococcus aureus and other gram-positive pathogens), child middle-ear infections (caused by Haemophilus influenzae , for example), common dental plaque formation, and gingivitis, all of which are caused by biofilms, are hard to treat or frequently relapsing, this figure appears realistic.”