Differences Among Strains of the Fusarium oxysporum-F. solani Complexes in Their Penetration of Hydrogel Contact Lenses and Subsequent Susceptibility to Multipurpose Contact Lens Disinfection Solutions

Abstract

The ability of Fusarium spp. to attach to and penetrate SH lenses in vitro varies with the lens type and strain, and this ability may make infectious keratitis more likely. We recommend the incorporation of a rubbing step in the MPS disinfection of hydrogel lenses to reduce the risk of fungal keratitis.

Fusariumkeratitis and contact lens wear: facts and speculations

“…In contrast, isolates of FOSC when suspended in PBS, expressed negligible or only latent capacities to invade the matrices of several hydrogel lens types [44,52]. However, when lenses were soaked first in SAB for 2 h prior to suspension in PBS, multiple isolates of FOSC attached to and invaded an expanded spectrum of SH and HEMA lenses, nearly to an extent previously observed only with lenses from patients [44]. Additionally, once penetrated, the lenses (some with resistant chlamydospores on and within the lens matrices (Fig.…”

“…and F. solani were observed to germinate on the hydrogel lens surface and penetrate the lens matrix [44,52]. The sites of attachment and degree of penetration were irregular and varied with the strain of fungus and type of lens.…”

“…2). These properties were proposed to facilitate the selective survival and growth of the fungus in drying and stressed MPS, mainly RML to the exclusion of most bacteria within the contact lens case [44].…”

“…Multiple lens types, including both conventional hydroxyethylmethylacrylate (HEMA) and high oxygen diffusion silicone hydrogel (SH), were involved in the recent outbreak of Fusarium keratitis (Table 1, Disposable lenses used beyond their manufacturers' recommended use time appeared a preeminent stress factor [22,23,25,42,44,52]. Contamination of used hydrogel contact lens cases by bacteria and fungi during consumer use, in conjunction with a role of the lenses as fomites in the transportation of microorganisms to the eye, have been commonly noted as risk factors for the development of keratitis [53Á57].…”

Evaluations of Shorter Exposures of Contact Lens Cleaning Solutions against Fusarium oxysporum Species Complex and Fusarium solani Species Complex To Simulate Inappropriate Usage

“…It is tempting to suggest that F. oxysporum is much more resistant to certain MPSs, and this probably explains its overwhelming presence among the isolates from the recent outbreak (3,8,21). An insight into this observed phenomenon has been provided in studies by Ahearn and colleagues, who reported that F. oxysporum strains showed greater penetration of contact lenses and survived better after treatment with MPS, while F. solani strains were easily removed (2,35). However, these experimental findings must be reconciled with clinical studies, where other institutions have reported more FSSC in their keratitis patients (3,16,32) Clearly, in vitro experiments are limited in simulating all of the conditions that predispose patients to Fusarium keratitis.…”