Silver-Impregnated Catheters

1 Central Venous Catheters Central venous catheters (CVCs) are widely used in hospital practice indeed it has been estimated that, in the United States alone, about 5 million of these units are inserted annually [52]. The widespread use of CVCs is associated with potential infective complications, with the annual incidence of catheter-related bloodstream infection estimated at around 80000 cases in the US [53, 54]. 

The use of silver may prove to be a valuable alternative in the treatment of UTIs, as it is known to be highly active against a broad spectrum of bacteria commonly found in these conditions. Recently, when a new technology where the entire catheter was impregnated with silver nanoparticles (3-8 nm) was described, the 

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Guggenbichler JP, Samuel U. 2004. Prevention of catheter-related infections The potential of a new nano-silver impregnated catheter. Int J Antimicrob Agents 23 S15-S7S. 

Lundeberg, T. (1986) Prevention of catheter-assodated urinary trad infections by use of silver impregnated catheters. Lancet, 2, 1031. 

A meta-analysis of the clinical and economic effects of chlorhexidine and silver sulfadiazine antiseptic-impregnated catheters has been undertaken (60). The costs of hypersensitivity reactions were considered as part of the analysis, and the use of catheters impregnated with antiseptics resulted in reduced costs. The analysis used the higher estimated incidence of hypersensitivity reactions occurring in Japan, where the use of chlorhexidine-impregnated catheters is still banned (61). 

However, clinical studies have proved that the antibacterial activity of silver-sulfadiazine impregnated catheters decreased rapidly. 

Hasaniya, N. W., Angelis, M., Brown, M. R., and Yu, M., Efficacy of subcutaneous silver-impregnated cuffs in preventing central venous catheter infections, Chest, 19% 109(4) 1030-1032. 

Maki, D. G., Cobb, L., Garman, J. K., Shapiro, J. M., Ringer, M., and Helgerson, R. B., An attachable silver-impregnated cuff for prevention of infection with central venous catheters A prospective randomized multicenter trial, Am. J. Med., 1988 85(3) 307-314. 

Groeger JS, Lucas AB, Coit D, et al. A prospective, randomized evaluation of the effect of silver impregnated subcutaneous cuffs for preventing tunneled chronic venous access catheter infections in cancer patients. Ann Surg August 1993 218(2) 206-10. 

Kalfon P, de VC, Samba D, et al. Comparison of silver-impregnated with standard multi-lumen central venous catheters in critically iU patients. Crit Care Med April 2007 35(4) 1032-9. 

Geis, D.-B.C., 1999. Reduced rates of catheter-associated infection by use of a new silver-impregnated central venous catheter. Infection 27, S56-S60. 

Other authors reported no microbicidal effect of silver. The survival of three bacterial species and C. albicans on a silver-impregnated polymer was not found to be influenced by the silver incorporation (Kampf et al., 1998). Using confocal laser scanning microscopy, Cook et al. (2000) observed that a silver-coated prosthetic heart valve sewing cuff was colonized by a higher number of bacteria S. epidermidis) than an uncoated cuff. McLean et al. (1993) reported that only a combination of silver and copper in multilayer surface films on catheter materials provided enhanced antimicrobial activity compared to uncoated or only silver-coated surfaces. 

By taking into account the existence of silver nanoparticle-impregnated catheters for clinical use, hemocompatibility becomes a top safety concern. Previous reports have suggested that nanoparticles present in the blood were associated with thrombosis and the activation of immunological reactions. Various studies have provided evidence that exposme to ambient ultrafine particles elicits an inflammatory response in vascular endothelial cells and blood cells [104, 105]. In the case of silver, a recent study revealed that silver nanoparticles could greatly enhance the electron-transfer reactivity of myoglobin [106]. 

However, the majority of the antimicrobial-treated CVCs available on the market (Table 12.4) are obtained by adsorption of the drug onto the catheter surface, since this method is facile, inexpensive, and potentially apphcable for a wide range of drugs. Only in the two types of CVCs treated with silver, the antimicrobial agents are impregnated in the polymer bulk. Often, to improve drug affinity for the device surface, cationic surfactants are used, such as tridodecylmethylammonium chloride (TDMAC) and benzalkonium chloride employed for the adsorption of minocycline/rifampin and heparin, respectively. 

Bach A. Clinical studies on the use of antibiotic- and antiseptic-bonded catheters to prevent catheter-related infection. Zentralbl Bakteriol December 1995 283(2) 208-14. Greenfeld JI, Sampath L, Popilskis SJ, et al. Decreased bacterial adherence and biofilm formation on chlorhexidine and silver sulfadiazine-impregnated central venous catheters implanted in swine. Crit Care Med May 1995 23(5) 894-900. 

Rupp ME, Lisco SJ, Lipsett PA, et al. Effect of a second-generation venous catheter impregnated with chlorhexidine and silver sulfadiazine on central catheter-related infections a randomized, controlled trial. Ann Intern Med October 2005 143(8) 570-80. Darouiche RO, Raad II, Bodey GP, et al. Antibiotic susceptibility of staphylococcal isolates from patients with vascular catheter-related bacteremia potential role of the combination of minocycline and rifampin. Int J Antimicrob Agents September 1995 6(l) 31-6. 

AntoneUi M, De PG, Ranieri VM, et al. Comparison of triple-lumen central venous catheters impregnated with silver nanoparticles (AgTive(R)) vs conventional catheters in intensive care unit patients. J Hosp Infect October 2012 82(2) 101-7. 

Reduction of catheter-related colonisation by the use of a silver zeolite-impregnated central vascular catheter in adult critical care. The Journal of Infection, 54(2), 146-50. 

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