Biofilm-associated infections

Rice, S. A., Mcdougald, D., Kumar, N., Kjelleberg, S. The use of quorum-sensing blockers as therapeutic agents for the control of biofilm-associated infections. Curr. Opin. Investig. Drugs 2005, 6, 178-184. 

P. Kaali, E. Stromberg, S. Karlsson, Prevention of biofilm associated infections and degradation of polymeric materials used in biomedical applications (INTECH Open Access Publisher, 2011), pp. 513-540... 

Because of the high resistance against antibiotics and chemotherapy, biofilm-associated infections usually lead to recurrent inflammation. Reoperation may be necessary, but inflammation could also result in osteomyelitis, amputation, or even death. The development of longer-term performing synthetic implants, showing reduced infectious complications, requires full understanding of bacterial adhesion. 

In the final chapter, biofilm formation is reviewed, covering knowledge about structure and biosynthesis of polysaccharide intercellular adhesins (PIAs) which are central to biofilm formation. This comprehensive chapter explains all PIA-related principles of medical device-associated infections. 

An important characteristic of microbial biofilms is their innate resistance to immune system and antibiotic killing (89, 90). This has made microbial biofilms a common and difficult-to-treat cause of medical infections (87,91,92). It has recently been estimated that over 60% of the bacterial infections currently treated in hospitals are caused by bacterial biofilms (91). Several ehronic infections (e.g. respiratory infections caused by Pseudomonas aeruginosa in the cystic fibrosis lung. Staphylococcal lesions in endocarditis, and bacterial prostatitis, primarily caused by Escherichia coli) have been shown to be mediated by biofilms (93). More notably, biofilms (particularly of Staphylococcus aureus, P. aeruginosa, and E. coli) are also a major cause of infections associated with medical implants (94, 95). The number of implant-associated infections approaches 1 million per year in the United States alone, and their direct medical costs exceed 3 billion annually (96). Thus, there is an urgent need to find novel approaches to eradicate biofilms. 

J. Del Pozo, R. Patel, The challenge of treating biofilm-associated bacterial infections, Clin. Pharmacol. Then 82 (2007) 204-209. 

A wide variety of natural and synthetic materials have been used for biomedical applications. These include polymers, ceramics, metals, carbons, natural tissues, and composite materials (1). Of these materials, polymers remain the most widely used biomaterials. Polymeric materials have several advantages which make them very attractive as biomaterials (2). They include their versatility, physical properties, ability to be fabricated into various shapes and structures, and ease in surface modification. The long-term use of polymeric biomaterials in blood is limited by surface-induced thrombosis and biomaterial-associated infections (3,4). Thrombus formation on biomaterial surface is initiated by plasma protein adsorption followed by adhesion and activation of platelets (5,6). Biomaterial-associated infections occur as a result of the adhesion of bacteria onto the surface (7). The biomaterial surface provides a site for bacterial attachment and proliferation. Adherent bacteria are covered by a biofilm which supports bacterial growth while protecting them from antibodies, phagocytes, and antibiotics (8). Infections of vascular grafts, for instance, are usually associated with Pseudomonas aeruginosa Escherichia coli. Staphylococcus aureus, and Staphyloccocus epidermidis (9). 

In the introductory part of this chapter, it is mentioned that in various systems and applications, bioadhesion is an unwanted phenomenon. Different strategies may be taken to prevent or suppress (microbial) cell adhesion and biofilm formation. Coating the surface with antimicrobial agents such as silver nanoparticles may have some effect. However, the hazard of release of such toxic particles in the body, product, or enviromnent puts severe restrictions on their use. Furthermore, prophylactic supply of antibiotics to treat biomaterials associated infections is in most cases highly unsuccessful, because in biofilms bacteria tend to be resistant against antibiotics. 

Donlan RM. Biofilms and device-associated infections. Emerg Infect Dis 2001 7 277-81. 

Saginur R, StDenis M, Ferris W, Aaron SD, Chan F, Lee C, et al. Multiple combination bactericidal testing of staphylococcal biofilms fiom implant-associated infections. Antimicrob Agents Chemother 2006 50 55-61. http //dx.doi.0rg/lO.l 128/aac.50.1.55-61.2006. 

This chapter will be focused on antimicrobial PUs for intravascular applications. First, a classification of the types of PU intravascular devices and their impact in the medical held will be inhoduced. Then, a survey of infections associated with intravascular devices in terms of incidence, etiology, and pathogenesis will be presented. Next, management of device-related infections and the role of modified PUs in preventing intravascular device-related infections will be discussed. Finally, the future direction of novel antimicrobial polymers as biomaterials for the development of devices preventing biofilm-based infections will be described. 

It is now widely accepted that nuCTobial biofihns play a key role in all types of health-care-associated infections and especially in those related to medical devices. Particularly, biofilm formation on the device surfaces contributes to the severity of these infections. Indeed the development of biofilm is responsible for the chronic nature of related infections, and for the inherent resistance to antibiotic therapy. Raad et al. were among the first investigators who isolated biofilm-producing microorganisms from the intraluminal surface of CVCs, which r ained in situ for more than 30 days. 

Biofilm-based central line-associated infections are often polymicrobial. Particularly, C. albicans and S. aureus can be found coexisting as polymicrobial biofilms... 

It is worthwhile drawing attention to health hazards associated with film infected water systems which also cause corrosion. Two of the most common are Legionnaires disease and so called humidifier fever . Because of strong adhesion of biofilms and diffusion rates through the film treatment based on cleaners and chemical sterilisers such as chlorine often fail similar considerations apply to other systems in industry, e.g. food, paint, oil and gas are examples where biofilm activities have given massive problems. 

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