Microsporidia and Acanthamoeba: the role of emerging corneal pathogens

Tu, Elmer Y.; Joslin, Charlotte E.

doi:10.1038/eye.2011.315

Cited by 15 publications

(13 citation statements)

References 37 publications

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“…Despite the recall of Complete MoisturePlus in 2007, the number of Acanthamoeba keratitis cases has not decreased to baseline levels identified prior to 2003-2004, indicating that additional risk factors introduced during this time are involved. 5,7,11 Since the introduction of topical ophthalmic ciprofloxacin hydrochloride in the early 1990s, initial community-based therapy for presumed infectious keratitis had predominantly been BAKcontaining fluoroquinolones until the introduction of moxifloxacin to the US market in 2003. [20][21][22] Introduction to other countries also reporting Acanthamoeba outbreaks was staged-Singapore in November 2004, Japan in 2006, and later in Europe.…”

Section: Commentmentioning

confidence: 99%

“…10 Despite these efforts, a unique, primary risk factor for the sudden increase in cases remains undiscovered, suggesting that multiple risk factors may be involved. 5,11 Ophthalmic formulations, specifically multidose commercial preparations, are required to resist contamination as demonstrated by a standard test regimen against a small number of stock bacteria and fungi, 12 usually achieved by the addition of a preservative compound with a non-specific antimicrobial spectrum extending far beyond the test organisms. Benzalkonium chloride (BAK), the predominant ophthalmic drug preservative for the last several decades, is a quaternary ammonium surfactant with this broad range of antimicrobial activity.…”

mentioning

confidence: 99%

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Effect of Low Concentrations of Benzalkonium Chloride on Acanthamoebal Survival and Its Potential Impact on Empirical Therapy of Infectious Keratitis

Tu¹,

Shoff²,

Gao³

et al. 2013

JAMA Ophthalmol

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The significant antiacanthamoebal effect of benzalkonium chloride, at or below concentrations used for preservation of common ophthalmic preparations, should be understood both when choosing empiric antibiotic therapy for infectious keratitis and when assessing the persistent rise in Acanthamoeba cases in the United States since 2003. Objective: To characterize the antiacanthamoebal efficacy of low concentrations of benzalkonium chloride (BAK) for drug preservation and therapeutic effect against Acanthamoeba. Design: Experimental study with a review of the literature. Setting: Laboratory. Exposures: A concentration of 10 4 trophozoites of 3 wellcharacterized clinical strains of Acanthamoeba were exposed at 0.5, 2.0, 3.5, 5.0, and 6.5 hours to BAK (0.001%, 0.002%, and 0.003%), moxifloxacin hydrochloride (0.5%), and moxifloxacin (0.5%)ϩBAK (0.001% and 0.003%) with hydrogen peroxide (3%) and amoeba saline controls. Main Outcomes and Measures: Amoeba survival was calculated using the most probable number method recorded as log kill values. The relationship of BAK concentration and exposure time as well as the relative effect of BAK and moxifloxacin on acanthamoebal survival were analyzed. Results: Amoebicidal activity of BAK is both time dependent and concentration dependent in pooled and strain-stratified analyses (P Ͻ.001). Moxifloxacin demonstrated no significant independent inhibitory effect or additive effect to BAK efficacy on acanthamoebal survival. The profound antiacanthamoebal effect of BAK, 0.003%, was similar to that of hydrogen peroxide for certain strains. Conclusions and Relevance: Low concentrations of BAK, previously demonstrated to concentrate and persist in ocular surface epithelium, exhibit significant antiacanthamoebal activity in vitro at or below concentrations found in commercially available ophthalmic anti-infectives. The unexplained persistence of the Acanthamoeba keratitis outbreak in the United States, clusters abroad, and clinical studies reporting resolution or modification of Acanthamoeba keratitis without specific antiacanthamoebal therapy suggests that other contributing factors should be considered, including changes in the formulations used for empirical therapy of presumed infectious keratitis occurring in the same period.

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Section: Commentmentioning

confidence: 99%

mentioning

confidence: 99%

Effect of Low Concentrations of Benzalkonium Chloride on Acanthamoebal Survival and Its Potential Impact on Empirical Therapy of Infectious Keratitis

Tu¹,

Shoff²,

Gao³

et al. 2013

JAMA Ophthalmol

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“…Risk cofactors are particularly associated to the loss of the integrity of the corneal surface,12 be it consequent to trauma or abrasions from an external contaminated object or a secondary microtrauma produced by the use of CL, which both favor the penetration of the parasite into the corneal tissue 13. Moreover, even the exposure to environmental pollution could be associated to the developing of this keratitis, as reported by Lalitha et al14…”

Section: Introductionmentioning

confidence: 95%

Results of case-control studies support the association between contact lens use and Acanthamoeba keratitis

Pacella¹,

Torre²,

Giusti³

et al. 2013

OPTH

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BackgroundAcanthamoeba keratitis (AK) is ever more frequently reported in industrialized countries. The loss of the corneal surface integrity consequent to secondary microtrauma produced by the use of contact lens (CL) favors the penetration of the parasite into the corneal tissue.ObjectivesA scientific review was performed to investigate the association of CL wear as an Acanthamoeba keratitis (AK) risk factor.MethodsA computerized screening of 7834 Medline articles (4623 from PubMed; 3211 from Scopus) used a strict selection criteria of case-control studies involving CL wear and/or trauma.ResultsThe search yielded five case-control studies published from 1995 to 2012. All studies included showed a statistically significant positive association between AK and CL use, with a combined odds ratio (OR) of 10.21 (95%, confidence intervals [CI]; 3.57–27.64).Statistical analysisAll studies included showed a statistically significant positive association between AK and CL use, though with differing OR values.ConclusionThough rare, AK should be held in higher consideration when ophthalmologists are faced with CL users exhibiting simplex-like lesions associated with circular stromal infiltrates and disproportionate ocular pain in respect to the objective clinical picture.

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“…Man spricht heute von der zunehmenden Rolle von kornealen Krankheitserregern, die früher kaum beachtet werden mussten. Hier sind obligat intrazelluläre Parasiten wie Microsporidien und Hefen zu nennen, neben den pathogenen Einzellern wie den Akanthamöben [39]. [46].…”

Section: Umgebungseinflüsse Und Erregerspektrumunclassified

Kontaktlinsen und Keratitis

Bischoff

Brocks

2012

Klin Monatsbl Augenheilkd

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Keratitis is a rare but important and possibly sight threatening complication of Contact Lens wearing. Despite of the number of only about 1.7 keratitis cases per ophthalmolgist per year, this serious side effect needs knowledge and special diagnosis and treatment. Global changes of infectious agents and increase of previously unsuspicious pathogens in combination with a high degress of non-compliance indicate that Contact Lens wearing must be accompanied careful ophthalmologist's medical care and after-care.

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Microsporidia and Acanthamoeba: the role of emerging corneal pathogens

Abstract: Parasitic organisms are increasingly recognized as human corneal pathogens.

Cited by 15 publications

References 37 publications

Effect of Low Concentrations of Benzalkonium Chloride on Acanthamoebal Survival and Its Potential Impact on Empirical Therapy of Infectious Keratitis

Effect of Low Concentrations of Benzalkonium Chloride on Acanthamoebal Survival and Its Potential Impact on Empirical Therapy of Infectious Keratitis

Results of case-control studies support the association between contact lens use and Acanthamoeba keratitis

Kontaktlinsen und Keratitis

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