Phosphorylcholine impairs susceptibility to biofilm formation of hydrogel contact lenses.
OBJECTIVE
To compare silicone-hydrogel, poly(2-hydroxyethyl methacrylate) (pHEMA), and phosphorylcholine-coated (PC-C) contact lenses in terms of their susceptibility to biofilm formation by Staphylococcus epidermidis and Pseudomonas aeruginosa.


METHODS
Laboratory investigation.


METHODS
Biofilm formation on colonized test lenses was evaluated with confocal microscopy and in vitro antibiotic susceptibility assays. The results of the latter assays were compared with those performed on planktonic cultures of the same organism.


RESULTS
For both microorganisms, sessile colonies on silicone-hydrogel and pHEMA lenses displayed lower antibiotic susceptibility than their planktonic counterparts. In contrast, the susceptibility of cultures growing on PC-C lenses was comparable with that for planktonic cultures. In particular, minimum inhibitory concentration for Tazocin (piperacillin plus tazobactam; Wyeth Pharmaceuticals, Aprilia, Italy; S. epidermidis) and gentamicin (P. aeruginosa) was identical, either in the presence of PC-C support or in planktonic cultures (Tazocin, </= 0.2 mug/ml; gentamicin, 0.4 mug/ml). Minimum inhibitory concentration for imipenem (P. aeruginosa) was two-fold higher for PC-C lenses (0.4 mug/ml) with respect to planktonic cultures (0.2 mug/ml). Confocal microscopy of lenses colonized for 24 hours with P. aeruginosa green fluorescent protein-expressing cells revealed a sessile colonization on silicone-hydrogel lens and a few isolated bacterial cells scattered widely over the surface of the PC-C lens.


CONCLUSIONS
An increase in antibiotic susceptibility of bacterial cultures was associated with diminished bacterial adhesion. Our results indicate that PC-C lenses seem to be more resistant than silicone-hydrogel and pHEMA lenses to bacterial adhesion and colonization. This feature may facilitate their disinfection.
Selan
Laura
L
Department of Public Health Sciences G. Sanarelli, La Sapienza University, Rome, Italy.
Palma
Stefano
S
Scoarughi
Gian Luca
GL
Papa
Rosanna
R
Veeh
Richard
R
Di Clemente
Daniele
D
Artini
Marco
M
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D020099:Coated Materials, Biocompatible; D003263:Contact Lenses, Hydrophilic / Q000382:microbiology*; D005839:Gentamicins / Q000494:pharmacology; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D015378:Imipenem / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D010767:Phosphorylcholine / Q000494:pharmacology*; D010878:Piperacillin / Q000494:pharmacology; D000077725:Piperacillin, Tazobactam Drug Combination; D011102:Polyhydroxyethyl Methacrylate; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000502:physiology*; D012825:Silicon; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000502:physiology*
D000900:Anti-Bacterial Agents; D020099:Coated Materials, Biocompatible; D005839:Gentamicins; D010767:Phosphorylcholine; D000077725:Piperacillin, Tazobactam Drug Combination; D011102:Polyhydroxyethyl Methacrylate; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D015378:Imipenem; D010397:Penicillanic Acid; D010878:Piperacillin; D012825:Silicon