Antimicrobial Coatings to Prevent Biofilm Formation on Medical Devices - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 174

pieces were stored in PBS at room temperature for 6-8 weeks before utilizing them
in the static biofilm system. Regardless of the storage time, the SCAA-coated pieces
still significantly inhibited the development of AH133 biofilms (Tran et al. 2012b ).
In the flow-through continuous-culture system, catheter pieces were colonized with
AH133 for 1 h and subjected to a continuous stream of TSB for 5 days using a
peristaltic pump (Tran et al. 2012b ). Image analysis revealed the AH133 formed
well-developed biofilms on the outer and inner surfaces of the uncoated catheters
(Tran et al. 2012b ). However, no biofilm was detected on either surface of the
SCAA-coated catheter pieces (Tran et al. 2012b ).
Tran et al. utilized the murine model of biofilm development to determine if
SCAA-coated catheter inhibits the development of AH133 biofilm in vivo (Tran
et al. 2012b ). Catheter pieces were subcutaneously inserted in the back of adult
mice (Tran et al. 2012b ). Strain AH133 was inoculated within the vicinity of the
inserted catheter pieces (Tran et al. 2012b ). After 3 days, the catheter pieces were
extracted, and biofilms were analyzed (Tran et al. 2012b ). Strain AH133 formed
mature biofilm on the inner and outer surfaces of the uncoated catheter pieces
(Fig. 1 ) (Tran et al. 2012b ). Structural aspects of the biofilm were examined using
the COMSTAT program (Heydorn et al. 2000 ). On uncoated catheter pieces,
AH133 produced biofilm with marked biomass, average thickness, surface area,
and surface area/biomass ratio (Tran et al. 2012b ). In contrast, no biofilm developed
on either the outer or the inner surfaces of the SCAA-coated catheter pieces (Tran
et al. 2012b ).
3 Urinary Tract Catheters
3.1 Catheter-Associated Urinary Tract Infections
Catheter-associated urinary tract infections (UTIs) are the most common type of
healthcare-related infections, accounting for about 40 % of healthcare associated
infections in the USA (NNIS 2004 ; Tambyah 2004 ). In the USA, more than
30 million bladder catheters are placed annually (Tambyah 2004 ). As a result,
thousands of cases of catheter-associated UTIs occur (Feng et al. 2000 ). It is
estimated that 10-50 % of patients undergoing short-term catheterization (up to
7 days) develop catheter-associated urinary tract infections whereas almost all
patients undergoing long-term catheterization (greater than 28 days) will develop
catheter-associated urinary tract infections (Stickler 1996 ).
The urinary tract catheter system may either be closed or open. Whereas in the
closed system, the catheter empties into a plastic bag, in the open system, the
catheter drains into an open collection container (Kaye and Hessen 1994 ). There-
fore, open system catheters become contaminated quickly and patients develop
catheter-associated urinary tract infections (Stickler 1996 ). In vitro and in vivo
studies demonstrated the development of bacterial biofilm on urinary catheters.