Antimicrobial Coatings to Prevent Biofilm Formation on Medical Devices - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 179

that were externally coated with ciprofloxacin liposome. The average time to
positive E. coli urine cultures improved from 3.5 to 5.3 days when ciprofloxacin
liposome-coated catheters were compared to uncoated catheters in a rabbit model
(Pugach et al. 1999 ). Coated catheters also decreased the bacteremia rate by 30 %
(Pugach et al. 1999 ). The risk associated with the antibiotic-coated urinary catheters
is the emergence of antibiotic-resistant strains (Siddiq and Darouiche 2012 ). Due to
the higher concentration of bacteria in urine than on skin, such a risk is greater with
urinary than vascular catheters (Siddiq and Darouiche 2012 ).
3.2.6 Quorum-Sensing Inhibitors
The cell-to-cell communication system (quorum sensing, QS) influences biofilm
development and the production of different virulence factors in Gram-negative and
Gram-positive bacteria (Njoroge and Sperandio 2009 ). One of the Staphylococcus
aureus QS systems consists of RNAIII activating protein (RAP) which phosphor-
ylates its target protein, the 21 Kda TRAP (Njoroge and Sperandio 2009 ). The QS
inhibitor RNAIII-inhibiting peptide (RIP) inhibits TRAP phosphorylation (Gov
et al. 2001 ). RIP has been shown to inhibit biofilm formation and staphylococcal
infection (Balaban et al. 2005 ). Cirioni et al. ( 2007 ) implanted RIP-coated urethral
stents in rat bladders and examined the effectiveness of RIP-coated catheters in
inhibiting Staphylococcus aureus biofilm. RIP suppressed the formation of Staph-
ylococcus aureus on urethral stents and significantly reduced the number of Staph-
ylococcus aureus microorganisms (CFU/ml) in urine cultures (Cirioni et al. 2007 ).
When the RIP-coated urethral stents were utilized in conjunction with the antibiotic
teicoplanin (intraperitoneally injected), no bacteria were recovered either on the
stent or in urine cultures (Cirioni et al. 2007 ).
3.2.7 Biological Coatings
A novel approach to prevent the development of catheter-associated biofilm by
pathogenic bacteria in patients who require a long-term urinary catheter is coating
the surfaces of the catheter with benign bacteria (Sunden et al. 2006 ). Studies were
conducted using the nonpathogenic Escherichia coli strain 83972 which persis-
tently colonized a person without symptomatic infection during 3 years of obser-
vation (Andersson et al. 1991 ). An in vivo study showed that the non-p fimbriae
PapG deletion mutant of 83972 (Hu2117) reduced the colonization of urinary
catheters by different uropathogens (Trautner et al. 2002 ). An initial clinical
study showed that the introduction of a Hu2117-coated indwelling catheter in a
human bladder reduced the incidence of symptomatic urinary tract infections
(Trautner et al. 2007 ). However, both in vitro and in vivo studies demonstrated
that in comparison with the absence of uropathogens, the adherence of 83920 or
Hu2117 to an unmodified silicone urinary catheter is low (Trautner et al. 2007 ,
2008 ). Mannose is the ligand for FimH which is the adhesive component of type I