Most of the disease-causing bacteria secrete matrix-like layers around themselves called biofilms. These biofilms act as thick barriers limiting the entry of drugs and helping the bacteria become resistant to antibiotics. Most of the disease-causing bacteria secrete matrix-like layers around themselves called biofilms. These biofilms act as thick barriers limiting the entry of drugs and helping the bacteria become resistant to antibiotics. Cell & Microbiology Molecular & Computational biology Phys.org – latest science and technology news stories