INTRODUCTION Matrix-embedded microbial assemblies that adhere to surfaces, whether biological or inanimate, are termed biofilms. Biofilms are structurally and dynamically complex biological systems. The main constituents of biofilm are microbial cells, extracellular polymeric substances (EPS) produced by the cells and often referred to as glycocalix or slime, and, depending on the environment, inorganic precipitates. EPS are a complex mixture of macro- molecules such as polysaccharides, proteins, nucleic acids and lipids (1) Exopolymers facilitate cell adhesion to the substratum and give structural integrity to the biofilm matrix (2). The presence of EPS enhances bacterial resistance to deleterious external factors, including naturally occurring and synthetic antimicrobial agents. Extensive reviews are available on biofilms and their environmental and health impact (3-6). Implant Infections The International Journal of Artificial Organs / Vol. 29 / no. 4, 2006 / pp. 443-452 Microbially-influenced corrosion: Damage to prostheses, delight for bacteria I.B. BEECH 1 , J.A. SUNNER 2 , C.R. ARCIOLA 3 , P. CRISTIANI 4 1 School of Pharmacy and Biological Sciences, University of Portsmouth, Portsmouth - UK 2 Department of Chemistry and Biochemistry, Montana State University, MT - USA 3 Research Unit on Implant Infections, Rizzoli Orthopaedic Institute, Bologna; Experimental Pathology Department, University of Bologna, Bologna - Italy 4 Environmental Diagnostic Unit, CESI, Centro Elettrotecnico Sperimentale Italiano Giacinto Motta, Milan - Italy © Wichtig Editore, 2006 0391-3988/443-10 $15.00/0 ABSTRACT: In natural and man-made environments, microbial communities thrive as biofilms on living (e.g. tissue) and inanimate (e.g. plastic, metal, wood, mineral) surfaces. Biofilms are found in a wide range of aqueous habitats, including physiological fluids. Numerous types of microorganisms are able to colonize catheters, implants, prosthetics, and other medical devices manufactured from different metallic and non-metallic materials dwelling within a human body. The development of biofilm is facilitated by the production of extracellular polymeric substances (EPS). Biofilms formed on surfaces of metallic materials may alter interfacial electrochemical processes, which can lead to increased corrosion of the colonized substratum. Deterioration of metallic materials in the presence of a biofilm is termed biocorrosion or microbially-influenced corrosion (MIC). In the field of biomaterials, “biocorrosion” is commonly used when describing the effect of host tissue on the corrosion of implant metals and alloys. Therefore, to avoid confusion, we will here use the term MIC as a reference to biofilm-influenced corrosion. It is important to realise that although most metals are prone to microbial colonization, i.e. to biofouling, this does not imply that they are susceptible to MIC. For example, a metal such as titanium, accumulates biofilm, however, it still demonstrates excellent resistance against MIC. Corrosion is, by definition, an electrochemical process, therefore, electrochemical techniques are frequently employed to determine and measure the rate of abiotic, as well as biologically driven corrosion reactions. This communication addresses the use of electrochemical techniques for monitoring (i) biofilm formation on and (ii) MIC of implant metals and alloys. (Int J Artif Organs 2006; 29: 443-52) KEY WORDS: Biofilms, Microbially-influenced corrosion, Prosthesis, Electrochemical methods, Metallic materials