Biomedical Engineering Reference
In-Depth Information
4.2 Prevention Against Catheter-Related Blood Stream
Infections
Biofilms play a pivotal role in healthcare-associated infections, especially those
related to the implantation of medical devices, such as intravascular catheters,
urinary catheters, and orthopaedic implants. Implants act as passive surfaces
prone to bacterial adhesion and biofilm formation. This tendency can result in
implant-associated infection of the surgical site. In spinal surgery, implant-
associated deep body infections are still a major problem (Trampuz and Widmer
2006
). Some bacteria produce slime, which is responsible for bacterial adhesion
and formation of biofilms on artificial surfaces. This slime is composed of proteins,
hexosamines, neutral sugars, and phosphorus-containing compounds. If slime-
forming bacteria colonize an artificial surface and develop a biofilm, this layer
protects the bacteria from antibiotic agents. Thus, treatment against implant-
associated infection must target the development of a biofilm (Secinti et al.
2011
).
The most successful approaches for the control and prevention of infections due
to adhesion, colonization, and biofilm formation on medical devices have been
described in a review article by Francolini and Donelli (
2010
). Readers are
suggested to go through this article for more detailed strategies currently in use
for preventing biofilm formation on medical implants. In this chapter we will be
reviewing developments in novel strategies to prevent biofilm infection of implants
and tissues.
4.2.1 Lock Therapy Approach
Nosocomial infections associated with medical devices represent a large proportion
of all cases of hospital-acquired infections (Bell
2001
). In particular, insertion of
any vascular catheter can result in a catheter-related infection, as microorganisms
can colonize external and internal catheter surfaces. Adherence to the catheter
surface is facilitated by host proteins such as fibronectin and fibrinogen, which
can then lead to biofilm formation (Christner et al.
2010
). Such problems can be
overcome by one of the approaches termed lock therapy. This approach is currently
recommended and employed in treating catheter-related bloodstream infections
(CRBSI), in particular for long-term catheters, according to the Infectious Diseases
Society of America's guidelines (Mermel et al.
2009
). The choice of antibiotics
used in the lock technique is dependent on the pathogen suspected of infecting the
catheter lumen, characteristics of the organism (i.e., ability to produce slime,
adherence to host proteins), and the pharmacodynamic properties of the antimicro-
bial agent. Lock therapy involves the coating of high doses of an antimicrobial
agent [from 100- to 1,000-fold the minimal inhibitory concentration, (MIC)]
directly into the catheter in order to “lock” it for a certain period of time (from
hours to days) (Carratala
2002
). If host proteins such as fibronectin, fibrinogen, and
fibrin are present in the catheter lumen, heparin may increase the efficacy of the
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