Biofilms are a “slime of bacterial colonies”. What makes these structures special is that living within the glued communities enable its resident bacteria to become resistant to antibiotics and as a consequence execute precise attacks against the immune system.
They're Found Everywhere:

Biofilms have been around for at least 3.3 billion years forming on every wet or moist surface in the world.

They’re not Simple:

They are made up of multiple types of bacteria

They're Tough:

When bacteria exist in biofilm they can become 1000 times more resistant to antibiotics

They're Smart:

The biofilm residents talk to each to coordinate the behavior of the entire community

They Survive:

Biofilm is a bacterial fortress in a hostile environment

They Persist in Cystic Fibrosis:

These biofilms aggravate lung tissue damage

Biofilms are present in more than 60-80% of all human bacterial infections

Therapeutic failure when treating drug resistant infections is often associated with the existence of a biofilm. These biofilms are extremely difficult or even impossible to eradicate if the normal host defenses are compromised. Biofilm-associated drug resistance mechanisms ensure the survival and persistence of infections for years despite intensive antibiotic treatment or functional host defenses. Well-developed mature biofilms can thwart many antibiotic classes by intrinsic or adaptive resistances.