Implantable medical devices biofilms

Staphylococcus epidermidis Gram-positive, aerobic, catalase-positive cocci Implanted medical device/prosthetic device contaminant Biofilm-former... 

Biofilms consist of surface-associated colonies of bacteria and are a major concern for implanted medical devices and in many diseases [120-122], Bacterial biofilms are highly organized communities embedded in an exopolysaccharide matrix, and contain several layers of bacteria with distinct functions. Biofilms grow slowly but efficiently to coat abiotic surfaces, and can eventually almost completely fill up narrow tubing. Because of the entrenched structure of biofilms, an antibiotic cannot penetrate deeply enough into the distant parts of the biofilm to kill all bacteria. Therefore, biofilms are difficult to remove mechanically or by means of antibiotics or disinfectants. 

Systemic antibiotic treatment is a very common medical procedure all over the world. Nevertheless, it presents certain limitations and drawbacks, such as systemic toxicity, poor penetration in certain tissues, and poor control of local drug levels. Additionally, in the case of implantable medical devices, if bacteria (typically 5. aureus, S. epider-midis. Pseudomonas aeruginosa, E. colt, etc. ) adhere and proliferate, colonizing the implant surface and forming a biofilm, the patient may develop an infection despite systemic antibiotic treatment, which may lead to the rejection or removal of the implant (Fig. 10). Actually, an implant represents a challenge to the immune system. 

The photod)mamic approach has been applied for the cleaning and disinfection of artificial surfaces, especially for the destruction and inactivation of biofilms. In the majority of cases, it was proposed for the cleaning of surfaces in hospitals (Decraene et al., 2008a,b) and the disinfection of medical devices such as implants (Sharma et ah, 2008). Only a few papers on the application of PDT targeted to the needs of the food industry have been published. 

Biofilms are important for several reasons not the least of which are biocorrosion, reduced water quality and foci for the contamination of hygienic products [154-156]. Microbial colonization is also favoured on implanted biomaterials and medical devices resulting in increased infection rates and possible recurrence of infection [150],... 

Gram-positive opportunistic pathogens such as Staphylococcus epidermidis, S. aureus, E. faecalis and E. faecium have the capacity to form biofilms on foreign medical devices such as catheters, and surgical implants [52, 53], These microorganisms are normal inhabitants of healthy humans, in recent years, however, the bacteria emerged as a common cause of nosocomial infections [54], Interestingly,... 

When a medical device is in contact with body fluid such as blood, the first thing that occurs on the surface is protein adsorption [96-98]. Proteins in solution trying to minimize the total surface energy is the thermodynamic driving force of protein adsorption on solid surfaces. In blood contact protein adsorption is believed to be the initial event in thrombus formation [99-101], calcification [102-104], and biofilm attachment [105-107], which leads to the failure of implanted devices. Therefore, protein-reducing surface modifications of polyurethane biomaterials have been applied to improve the service life of implants. Previous studies of protein adsorption have focused on adsorption of albumin, IgG, and Fg, which are the predominant three proteins in blood plasma. Surface protein adsorption can be quantitated by several methods such as quartz crystal microbalance (QCM) [108-112], surface plasmon resonance (SPR) [113-118], and iodonization radiolabeling [78,119-125]. 

It is now well identified that bacteria connect to solid supports to shape structured communities called biofilms, also known as biopolymer matrix-enclosed microbial populations adhering to each other and/or surfaces [111]. Biofihns occur on both living and inert supports in all environments [112]. They influence various industrial and domestic areas [113] and are accountable for a broad range of human diseases [111], In view of the ever growing number of implanted patients, biofilm-linked infections of indwelling medical devices are more predominantly a foremost public health issue. Various examples of implants that can be inflated by biofilm formation are mechanical heart valves, catheters, pacemakers/defibriUators, ventricular assist devices, vascular prostheses, coronary stents, neurosurgical ventricular shunts, cerebrospinal fluid shunts, neurological stimulation implants, ocular prostheses, inflatable penile, cochlear, joint prostheses, fracture-fixation devices, breast, and dental implants and contact lenses, intrauterine contraceptive devices [114-116]. 

Microbes can form biofilms, which are surface-bound collections of cells with altered metabohsm [98, 99]. Because biofilms can cause disease or sepsis and are often resistant to drugs, medical devices and implants that resist biofilm formation... 

Contamination of ultrapure water by biofilm bacteria interferes with the production of microchips. In the beverage and food industry, biofilms on equipment surfaces can be involved in the spoilage of the products. Biofilms can also be important in the clinical setting, when they develop on medical devices (Donlan, 2001) such as implants, catheters, contact lenses, leading to life-threatening infections. 

Looking at the huge number of successes in the reduction and prevention of bacterial adhesion and biofilm formation in vitro (Baneijee et al., 2011 Campoccia et al., 2013 Carvalho et al., 2013 Epstein et al., 2012 Swartjes et al., 2013, 2014a,b Wong et al., 2011) and comparing them to the few concepts that have successfully been applied in clinical situations, the complexity of the problems associated with bacterial adhesion and biofilm formation becomes evident. This is partially attributable to the complexity of medical devices and implants, which all create interfaces between materials and biology. 

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