Adherence of Aspergillus species to soft contact lenses and attempts to inhibit the adherence

Utilizing hardware culture in a case of atypical keratitis

This case report describes the diagnosis and management of a 22-year-old male soft contact lens wearer, who presented with an atypical corneal ulcer in the right eye. The patient presented with a one-day history of significant eye pain, photophobia, and multiple pseudodendritic lesions on the cornea with stromal infiltrate; the differential remained broad. The management was guided by the culture of hardware of the patient's contact lenses, which grew aspergillus only in the affected contact. In cases where corneal culture is negative, multiple organisms have been isolated from the corneal culture, or in cases where there is no response to medical treatment, culture of hardware may be a useful methodology for isolating the offending microbe in infectious corneal ulcers.

Impact of contact lens group on antifungal efficacy of multipurpose disinfecting contact lens solutions

PURPOSE

To evaluate and compare the in vitro effectiveness of multipurpose contact lens solutions (MPDS) to inhibit fungal colonization of Food and Drug Administration (FDA) contact lens groups.

METHODS

Contact lenses from FDA groups I (low water content, nonionic), II (high water content, nonionic), III (low water content, ionic), and IV (high water content, ionic) were placed in sterile contact lens cases with 2 mL of ReNu MultiPlus, ReNu with MoistureLoc, or OPTI-FREE RepleniSH. Each contact lens-multipurpose solution combination was challenged with 0.1 mL of 10(6) colony-forming units/mL of Fusarium oxysporum and incubated at room temperature. Contact lenses and aliquots from phosphate-buffered saline rinse solutions, multipurpose solutions in cases, and lens cases were sampled at 24, 48, and 72 hours, plated on Sabouraud's agar, incubated at room temperature, and observed for growth (i.e., adhesion) for 1 to 7 days.

RESULTS

Used multipurpose contact lens solutions met or exceeded the 1-log reduction requirement of the FDA stand-alone test. Viable fungal colonies were recovered from group II lenses after 24 hours of storage in all three multipurpose solutions. Colonization was also detected with at least one contact lens-multipurpose solution pairing from groups I, III, and IV. Fungi were not recovered from lens-solution combinations after 24 hours or from phosphate-buffered saline solutions or lens cases at any period.

CONCLUSIONS

Antifungal activity of contaminated multipurpose solutions may be insufficient to prevent fungal colonization of contact lens materials despite meeting or exceeding the FDA stand-alone test criteria. Colonized lens may increase the risk of fungal keratitis.

Biomedical coatings based on chitin soluble extract for inhibition of fungal adhesion to polymeric surfaces

Indwelling medical devices made of polymeric materials, such as intravenous (IV) catheters, are known risk factors for development of fungal infection, particularly systemic candidiasis, that are a significant cause of morbidity and lethality in compromised patients. Candida can form a biofilm on the polymeric surface, serving as a nidus for systemic, difficult to eradicate infection. The current research focuses on development and study of a chitin soluble extract (CSE) coating on polyurethane (PU), in order to reduce the level of adherence of C. albicans to the PU surface. The immobilization of CSE onto the PU surface was performed using both, chemical binding and physical adsorption. Our results indicate that CSE develops a unique tertiary structure in which basic elements in the range of 100 nm build "fingers" and these "fingers" are arranged in a concentric structure around a center. The CSE coated films showed 75% inhibition of C. albicans adhesion for the chemical binding and 83% for the physical adsorption coating and even after 11 weeks the inhibitory effect on adhesion is still significant. Hence, our new coatings may lead to a new generation of medical devices with surfaces that can prevent fungal adhesion.

Effect of a chitin derivative in combination with cleaning and preservation solutions for contact lenses on adherence of fungi

The objective of the study was to evaluate the effect of supplementation of a chitin soluble extract (CSE) to clinically used commercial contact lenses' cleaning/preservation solutions on adherence of Aspergillus niger and Candida albicans to contact lenses. CSE (25 mg ml-1) was added to Solocare or Oxysept. Adherence of A. niger or C. albicans to contact lenses was assessed by exposing lenses to fungi in test solutions and enumeration of fungal colony forming unit. The study included three parts: (i) the disinfecting and adherence-inhibiting effect of Solocare and Oxysept: (ii) the adherence-inhibiting effect of CSE; (iii) the effect of Solocare + CSE or Oxysept + CSE on the fungal adherence to contact lenses. The experiments showed that: (i) Solocare had a significant disinfecting effect on A. niger and C. albicans while that of Oxysept was only minimal. (ii) Neither Solocare nor Oxysept had an inhibitory effect on the fungal adherence. (iii) CSE inhibited significantly the adherence of A. niger and C. albicans. (iv) Addition of CSE to Solocare or Oxysept resulted in almost complete inhibition of adherence Supplementing CSE to lenses' maintenance solutions increases their antifungal potential by adding anti-adherence activity to the disinfecting effect of these solutions, bearing the potential to serve as a prophylactic means.