A personal history of research on microbial biofilms and biofilm infections

The observation of aggregated microorganisms surrounded by a self-produced matrix adhering to surfaces or located in tissues or secretions is as old as microbiology, with both Leeuwenhoek and Pasteur describing the phenomenon. In environmental and technical microbiology, biofilms were already shown 80–90 years ago to be important for biofouling on submerged surfaces, e.g. ships. The concept of biofilm infections and their importance in medicine is, however, 40 years old and was started by Jendresen's observations of aquired dental pellicles and my own observations of heaps of Pseudomonas aeruginosa cells in sputum and lung tissue from chronically infected cystic fibrosis patients. The term biofilm was introduced into medicine in 1985 by Costerton. In the following decades, it became obvious that biofilm infections are widespread in medicine, and their importance is now generally accepted. The words ‘biofilms’ and biofilm infections has only been used in medicine for 30 years, but the phenomenon was detected already by Leeuwenhoek and Pasteur and by environmental microbiologists in the 1920s and 30s.