Biofilms and their Importance for Medical Microbiology

Overview

Microorganisms are able to adhere to various surfaces and to form there a three-dimensionalstructure known as biofilm. In biofilms, microbial cells show characteristics and behavioursdifferent from those of plankton cells. Intercellular signalisations of the quorum-sensing typeregulate interaction between members of the biofilm. Bacteria embedded in the biofilm can escapeand form well known planktonic forms, that are obviously only a part of the bacterial life cycle.Bacteria adhere also to medically important surfaces such as catheters, either urinary or intravenousones, artificial heart valves, orthopedic implants and so on and contribute to device-relatedinfections like cystitis, catheter-related sepsis, endocarditis etc. Once a biofilm has been establishedon a surface, the bacteria harboured inside are less exposed to the host’s immune response and lesssusceptible to antibiotics. As an important cause of nosocomial infections the biofilm must remainin the centre of the microbiologist’s attention.

Key words:
biofilm – planctonic growth – extracellular matrix – adherence to surfaces – quorum--sensing – resistance to antibiotics – chronic infections – persistent infections – plastic devices.