Bacteria are very good at sticking around.
The slimy, slippery 'biofilms' that they form on contact lenses, artificial heart valves and even some contraceptive devices can cause serious infections. The secret lies in the early stages of biofilm formation. Before bacteria colonize a surface they cruise along it looking for a suitable place to settle. These coatings are called polymeric brush layers, because they form a carpet of fine filaments poking out of the surface. Many assumed that PEGs simply stop bacteria reaching their ideal resting places.