Methods for studying biofilms produced by Staphylococcus epidermis

This chapter discusses the methods for studying biofilms produced by Staphylococcus epidermidis. Coagulase-negative staphylococci, in particular Staphylococcus epidermidis, once regarded as harmless skin commensals or contaminants of clinical material, are now accepted as major nosocomial pathogens. These bacteria are the most common cause of medical device-associated infection, especially if host immunity is depressed because of underlying disease or treatment with immunosuppressive drugs. Common types of device-associated infection include prosthetic valve endocarditis, infections of intravascular devices, peritonitis associated with continuous ambulatory peritoneal dialysis, central venous shunt infections, and bacteremia. Bloodstream infection with coagulase-negative staphylococci is also common in low birth weight newborns requiring intensive care. One of the problems encountered when examining the literature on biofilm production by S. epidermidis is the plethora of methods and approaches that have been used to investigate the interaction among the bacteria and glass or plastic surfaces. This chapter begins with an overview of methods that have been used to study biofilm formation by staphylococci. Methods for assaying early attachment and mature biofilm are described. Deceptively simple, these methods require careful attention to detail in order to obtain meaningful results. An attempt is made to discuss the problems associated with differences in methodology among research groups, by presenting methodology that is accepted by a majority of investigators