Bacterial adhesion to unworn and worn silicone hydrogel lenses.

Purpose: The objective of this study was to determine the bacterial adhesion to various silicone hydrogel lens materials and to determine whether lens wear modulated adhesion.

Methods: Bacterial adhesion (total and viable cells) of Staphylococcus aureus (31, 38, and ATCC 6538) and Pseudomonas aeruginosa (6294, 6206, and GSU-3) to 10 commercially available different unworn and worn silicone hydrogel lenses was measured. Results of adhesion were correlated to polymer and surface properties of contact lenses.

A new method for evaluation of compatibility of contact lenses and lens cases with contact lens disinfecting solutions.

Purpose: The purpose of this article is to describe new methodology, antimicrobial efficacy endpoint methodology to determine compatibility of contact lens solutions, lens cases and hydrogel lenses for disinfection (AEEMC), to evaluate the effect of a contact lens and a lens case on disinfection efficacy, and to present the ring test used to justify the use of the method in multiple laboratories.

Materials And Methods: A prototype solution containing chlorhexidine as the disinfecting agent and four representative lens types (group I and IV hydrogels and two silicone hydrogels) were used in these ring tests. Five laboratories participated in the chemical and microbiologic analyses.

Traversal of multilayered corneal epithelia by cytotoxic Pseudomonas aeruginosa requires the phospholipase domain of exoU.

Purpose: Pseudomonas aeruginosa isolates from microbial keratitis are invasive or cytotoxic toward mammalian cells, depending on their type III secreted toxins. Cytotoxic strains express ExoU, a phospholipase that contributes to corneal virulence. This study determined whether the ExoU phospholipase domain is required for P.

Effect of phospholipid deposits on adhesion of bacteria to contact lenses.

Purpose: Protein and lipid deposits on contact lenses may contribute to clinical complications. This study examined the effect of phospholipids on the adhesion of bacteria to contact lenses.

Methods: Worn balafilcon A (n = 11) and senofilcon A (n = 11) were collected after daily wear and phospholipids were extracted in chloroform:methanol.

Influence of protein deposition on bacterial adhesion to contact lenses.

Purpose: The aim of the study is to determine the adhesion of Gram positive and Gram negative bacteria onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials with and without lysozyme, lactoferrin, and albumin coating.

Methods: Four lens types (three SH-balafilcon A, lotrafilcon B, and senofilcon A; one CH-etafilcon A) were coated with lysozyme, lactoferrin, or albumin (uncoated lenses acted as controls) and then incubated in Staphylococcus aureus (Saur 31) or either of two strains of Pseudomonas aeruginosa (Paer 6294 and 6206) for 24 h at 37 °C. The total counts of the adhered bacteria were determined using the H-thymidine method and viable counts by counting the number of colony-forming units on agar media.

Effect of cholesterol deposition on bacterial adhesion to contact lenses.

Purpose: To examine the effect of cholesterol on the adhesion of bacteria to silicone hydrogel contact lenses.

Methods: Contact lenses, collected from subjects wearing Acuvue Oasys or PureVision lenses, were extracted in chloroform:methanol (1:1, v/v) and amount of cholesterol was estimated by thin-layer chromatography. Unworn lenses were soaked in cholesterol, and the numbers of Pseudomonas aeruginosa strains or Staphylococcus aureus strains that adhered to the lenses were measured.

In vitro deposition of lysozyme on etafilcon A and balafilcon A hydrogel contact lenses: effects on adhesion and survival of Pseudomonas aeruginosa and Staphylococcus aureus.

Purpose: To compare lysozyme adsorption and absorption and bacterial adhesion interactions on conventional (etafilcon A) and silicone (balafilcon A) hydrogel contact lenses.

Method: Lysozyme concentrations and activities associated with the lenses were determined after solvent extraction (trifluoroacetic acid/acetonitrile) and directly on the lenses without extraction with micrococcal- and micro-bicinchoninic acid (BCA) assays. Cells of bacteria with radiolabeled leucine and a cell recovery procedure were used in determinations of bacterial adhesion to lenses.

Relative primary adhesion of Pseudomonas aeruginosa, Serratia marcescens and Staphylococcus aureus to HEMA-type contact lenses and an extended wear silicone hydrogel contact lens of high oxygen permeability.

Purpose: To compare multiple strains of Pseudomonas aeruginosa and representative isolates of Staphylococcus aureus and Serratia marcescens for their relative primary adhesion to a high Dk silicone hydrogel lens (36% H2O) with that of a HEMA-type lens (58% H2O).

Methods: A radiolabeled cell procedure with a 2-h cell exposure was employed for enumerating bacteria on unworn and worn silicone hydrogel (balafilcon A) and HEMA-type (etafilcon A) hydrogel lenses.

Results: The degree of primary adhesion of P.

Effect of a multipurpose contact lens solution on the survival and binding of Acanthamoeba species on contact lenses examined with a no-rub regimen.

Purpose: To determine the effect of a multipurpose contact lens solution (ReNu MultiPlus Multi-Purpose Solution [RMP]) on the relative survival and binding of trophozoites and cysts of Acanthamoeba on hydrogel lenses with a no-rub regimen.

Methods: A stand-alone test procedure with RMP was conducted with and without the presence of organic soil (1 x 10(7) colony-forming units/mL heat-killed cells of Saccharomyces cerevisiae in heat-inactivated fetal bovine serum). Survival of amoebae on hydrogel contact lenses exposed to RMP was determined with a no-rub care regimen.

Validation of the Scan RDI for routine microbiological analysis of process water.

In this report, we review the validation methods and criteria specified in the PDA Technical Report No. 33 "Evaluation, Validation, and Implementation of New Microbiological Testing Methods" against data generated on the Chemunex Scan RDI. For each parameter, we have either reported data obtained in-house or reviewed information and documentation available from the manufacturer of the system.