Antimicrobial Coatings to Prevent Biofilm Formation on Medical Devices - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 182

Table 1 Coatings to block biofilm formation on contact lenses
Active component Mechanism of Action Advantages/disadvantages

(a) Coatings non-covalently attached
Furanones

Inhibition of quorum sensing Toxic to murine fibroblasts; showed

enhancement of biofilms at low
conc. a

Silver Formation of silver thiol bonds with

enzymes and membrane pro-
teins, possibly intercalates with
DNA

Toxic to mammalian cells; limited
activity; turns tissue black;
expensive; causes less killing
with Gram-positive bacteria b

Polyquaternium
compounds

Chelation of bacterial components Requires direct contact with bacte-
ria; causes cytotoxicity and
inflammation c

(b) Coatings covalently attached
Furanones
(fimbrolides)

Only causes about 1 log killing d Quorum-sensing inhibition

Only causes about 1 log killing e Polyquaternium

compounds

Rupture of bacterial cell membrane

Cationic peptides
(melimine)

Unknown Causes 1-4 logs of killing; stability

unknown from proteolysis f

Organoselenium
(polymerized
throughout the
contact lens)

Catalysis of superoxide formation Causes 5-7 logs of killing for Gram
negatives and Gram positives;
stable for the life of the lens
(if incorporated into the poly-
mer); inexpensive g

a

Kuehl et al. ( 2009 )

b

Atiyeh et al. ( 2007 ), Trop et al. ( 2006 ), Poon and Burd ( 2004 ), Hidalgo et al. ( 1998 ), Lee and
Moon ( 2003 ), Willcox et al. ( 2010 )
c Paimela et al. ( 2012 )
d Zhu et al. ( 2008 )
e Tiller et al. ( 2001 , 2002 )
f Willcox et al. ( 2008 ), Cole et al. ( 2010 ), Chen et al. ( 2012 ), Dutta et al. ( 2013 )
g Mathews et al. ( 2006 ), Tran et al. ( 2012a , 2013)

4.2 Antimicrobial Coating of Contact Lenses

In an attempt to improve the safety of the extended wear lenses, different materials
have been developed in order to reduce the possibility of biofilm formation which
could lead to bacterial keratitis and corneal ulcers. These compounds fall into two
main classes: (1) Compounds that must leach off the lens in order to kill bacteria or
inhibit their ability to form biofilms and (2) those compounds that are covalently
attached to the lens and yet can either kill bacteria or inhibit their ability to form
biofilms. These different coating materials are discussed in detail below and are
listed in Table 1 along with their advantages and disadvantages.