A novel in vitro model to study staphylococcal biofilm formation on intraocular lenses under hydrodynamic conditions.
OBJECTIVE
To develop a novel in vitro model to study the formation of Staphylococcus epidermidis biofilm on intraocular lenses (IOLs) from the primary-attachment phase to the biofilm-accumulation phase. The model was designed to replicate intraocular conditions especially by taking into account intraocular hydrodynamics.


METHODS
The model consisted of Tygon tubing connected to a vial containing acrylic hydrophobic IOLs. Three septa, placed along the tubing, allowed, respectively, the artificial aqueous humor's arrival and its elimination and the bacterial suspension's inoculation. A first pump allowed the aqueous humor's movement along the circuit, whereas a second one regulated the flow at which the nutritive environment was regenerated. The whole circuit was placed in a 34 degrees C water bath. Every 2 to 4 hours, lenses were taken from this environment. Bound bacteria were removed by scraping of optical faces and counted. All data are presented as the mean, SD, and coefficient of variation (CV). Comparisons among experiments were performed by one-way analysis of variance (ANOVA).


RESULTS
Calculated CVs were close to 30, showing that biofilm formation was homogeneous. Differences between experiments were nonsignificant for each removal time. The model provided the full kinetics of S. epidermidis biofilm growth on acrylic hydrophobic IOLs, with a stationary phase reached after 28 hours of incubation.


CONCLUSIONS
Biofilm development is modulated by many variables, including environmental factors. The findings in the present study of bacterial colonization of IOLs under intraocular physiological conditions allow understanding and more accurate targeting of biomedical device-related infections such as endophthalmitis.
Baillif
Stéphanie
S
Department of Ophthalmology, Edouard Herriot Hospital, Lyon, France.
Casoli
Emmanuelle
E
Marion
Karine
K
Roques
Christine
C
Pellon
Gérard
G
Hartmann
Daniel Jean
DJ
Freney
Jean
J
Burillon
Carole
C
Kodjikian
Laurent
L
D000180:Acrylic Resins; D001422:Bacterial Adhesion / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D015169:Colony Count, Microbial; D007910:Lenses, Intraocular / Q000382:microbiology*; D008954:Models, Biological; D011312:Pressure; D013212:Staphylococcus epidermidis / Q000502:physiology*
D000180:Acrylic Resins