Contamination of contact lens storage cases by Acanthamoeba and bacteria.

Abstract

In order to identify possible risk factors for microbial keratitis the storage cases for contact lenses of 102 asymptomatic lens wearers were tested for contamination by bacteria and free-living amoebae. Of this group 43 had significant counts ofviable bacteria and only 40 had negligible counts. Seven had contamination by acanthamoebae, of whom six also had significant bacterial counts. These results were categorised according to the type of contact lens worn and the lens disinfection method. The high rates of contamination by apathogenic and pathogenic organisms, in particular Acanthamoeba, and the probable support by contaminating bacteria of Acanthamoeba, are discussed.

Quantitative alterations of the commensal eye bacteria in contact lens wear

“…qualitative shift towards Gram-negative organisms, which constitute the majority of organisms isolated from lens storage cases and various in-use lens care solutions. [14][15][16] The observation that lens wearers did not yield sig nificantly more Gram-negative bacteria in this study may well reflect the efficiency of host antimicrobial defences at the ocular surface rather than fastidious attention to hygiene by the subjects studied.…”

Detection of Acanthamoeba on the ocular surface in a Spanish population using the Schirmer strip test: pathogenic potential, molecular classification and evaluation of the sensitivity to chlorhexidine and voriconazole of the isolated Acanthamoeba strains

“…Another factor to consider is that individuals affected by keratoconjunctivitis sicca, or dryeye syndrome, should be considered at risk of suffering AK since the lack of natural tear flow could induce the growth of unusual pathogens on the ocular surface. Other authors have reported the presence of both pathogenic bacteria and Acanthamoeba in the eye and on contact lenses, among other sites, and even Pseudomonas aeruginosa has been reported to play an important role in the formation of biofilms for the attachment of Acanthamoeba strains to contact lenses (Barker & Brown, 1994;Larkin et al, 1990;Simmons et al, 1998).…”

A review of 72 consecutive cases of Acanthamoeba keratitis, 1984–1992

“…Acanthamoeba thrive on bacterial colonies in culture, particularly on Gram-negative rods, and may reflect combined infection of the lenses or cases. 17,19,20 This sequence of events seems most likely where bacteria were isolated only days after the first symptoms were experienced. However, the cor neal ulceration seen in later-presenting acanthamoebal infection is a recognised risk factor for bacterial super infection.…”