Prognostic Factors Affecting Visual Outcome in Acanthamoeba Keratitis

Tu, Elmer Y.; Joslin, Charlotte E.; Sugar, Joel; Shoff, Megan E.; Booton, Gregory C.

doi:10.1016/j.ophtha.2008.04.038

Cited by 119 publications

(122 citation statements)

References 16 publications

Supporting

Mentioning

110

Contrasting

Unclassified

Order By: Relevance

“…Our observation is nevertheless consistent with other reports, which have shown that use of topical corticosteroids before acanthamoeba diagnosis and treatment may lengthen the duration of infection. 7,22,23 We also found that eyes with stromal involvement at presentation seemed to have longer microbial clearance times compared with those without stromal involvement, though this too lacked statistical significance. This finding is consistent with previous studies that have shown an association between deep stromal keratitis and worse disease outcomes.…”

Section: Discussionmentioning

confidence: 77%

“…This finding is consistent with previous studies that have shown an association between deep stromal keratitis and worse disease outcomes. 3,7 In this report, we estimate that the median clearance time of acanthamoeba from corneas treated with standard anti-acanthamoebal medications is 42.5 days (IQR 22-82 days). This indicates that 50% of our cases cleared between 4 and 12 weeks, though clearly the duration of treatment should be tailored for each individual case.…”

Section: Discussionmentioning

confidence: 93%

“…1 The analysis did not include diagnoses made with confocal microscopy, a technique, which in theory allows the identification of deeper stromal cysts, and could increase the overall sensitivity to detect acanthamoebal infection, and potentially extend the estimated clearance time. 7,17,20,21 This study should be repeated with confocal microscopy to determine if the clearance time estimates change with different diagnostic techniques. Identification of acanthamoeba infection might also depend on the quantity of organisms, which we did not take into account in our statistical analyses.…”

Section: Discussionmentioning

confidence: 99%

“…1,2 Factors associated with poor outcome include delay in diagnosis, corticosteroid use before diagnosis, stromal involvement, ring infiltrate, and poor visual acuity at presentation. [3][4][5][6][7] Treatment duration and follow-up are generally long, lasting till months. The persistence of corneal infection after initiation of appropriate therapy has not been well characterized.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microbiological cure times in acanthamoeba keratitis

Oldenburg

Keenan

Cevallos

et al. 2011

Eye

View full text Add to dashboard Cite

Aims The purpose of this study was to estimate the duration of treatment necessary for sequential acanthamoeba laboratory tests from corneal scrapings to become negative, and to assess predictors that affect this duration period. Methods We included all patients with at least one positive acanthamoeba culture or Giemsa stain at the F.I. Proctor Foundation Microbiology Laboratory from 1996 to 2009. A parametric survival analysis was performed among patients with repeat cultures to assess significant predictors for extended clearance time. Simulations were performed to estimate clearance time in the entire patient population, assuming imperfect sensitivity. Results Thirty-seven patients with laboratory evidence of acanthamoeba had testing at 69 time points. The median clearance time among eyes with repeat cultures was 42.5 days (interquartile range (IQR) 22.0-82.0 days; unadjusted parametric model). Initial visual acuity was the only predictor significantly associated with clearance time in univariate analyses (Po0.0001). Using initial visual acuity as a predictor for clearance time among the entire patient population, the estimated clearance time decreased to 38.7 days (95% confidence interval (CI) 27.9-53.5 days). When the imperfect sensitivity of the culture technique was also taken into account, the estimated clearance time was 44.1 days (95% CI 31.9-61.0 days). Conclusion The duration of infection with acanthamoeba keratitis undergoing treatment has not been well characterized. In this report we estimate a median clearance time of approximately 6 weeks, with an IQR of 22-82 days.

show abstract

Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Microbiological cure times in acanthamoeba keratitis

Oldenburg

Keenan

Cevallos

et al. 2011

Eye

View full text Add to dashboard Cite

show abstract

“…Disease severity can range from relatively minor epithelial and subepithelial diseases, which respond well to treatment, to refractory disease that can provoke corneal melting and perforation requiring therapeutic or tectonic corneal grafts (13). Currently, the most important factors affecting the prognosis are disease severity at presentation and the interval between symptom onset and the start of effective therapy (14,15); beginning therapy Ͼ3 weeks after symptom onset is associated with a worse prognosis.…”

mentioning

confidence: 99%

Influence of Acanthamoeba Genotype on Clinical Course and Outcomes for Patients with Acanthamoeba Keratitis in Spain

et al. 2014

View full text Add to dashboard Cite

Genotype T4 is by far the most frequent genotype of Acanthamoeba keratitis (AK) and therefore has been considered the most virulent. This study included 14 cases of AK of genotype T4 and three cases of non-T4 genotype. We found that cases of non-T4 genotype had a worse response to medical therapy, greater need for surgical intervention, greater risk of extracorneal involvement, and remarkably poorer final visual outcome than those of T4 genotype, suggesting an association between Acanthamoeba virulence and genotype that requires additional case investigation.A canthamoeba keratitis (AK) is a potentially blinding corneal infection in healthy immunocompetent individuals and is caused by free-living amoebae of the genus Acanthamoeba (1). Analysis of the 18S rRNA gene has identified 18 genotypes (T1 through T18) within this genus (2-4). Isolates from eight of the genotypic clades (T2, T3, T4, T5, T6, T10, T11, and T15) are confirmed causative agents of AK (4-12). Disease severity can range from relatively minor epithelial and subepithelial diseases, which respond well to treatment, to refractory disease that can provoke corneal melting and perforation requiring therapeutic or tectonic corneal grafts (13). Currently, the most important factors affecting the prognosis are disease severity at presentation and the interval between symptom onset and the start of effective therapy (14, 15); beginning therapy Ͼ3 weeks after symptom onset is associated with a worse prognosis.This study aimed to identify the genotypes of Acanthamoeba isolates from AK patients at our institution and to find any association between genotype and clinical outcomes.This revision was approved by the institutional review board at Hospital Universitario Ramón y Cajal. Seventeen amoebal isolates were obtained from the eyes of 17 patients with a clinical diagnosis of AK and who were followed prospectively at Hospital Universitario Ramón y Cajal, Madrid, Spain, from July 2009 to July 2013. The best spectacle-corrected visual acuity (BSCVA) in decimal Snellen fraction notation (1.0 indicates a normal value, and 0 indicates no vision at all), slit lamp and fundus examinations, and other events were recorded in the clinical notes. Tissue was obtained from each patient by epitheliectomy or by scraping the corneal ulcer when there was no epithelium left. A portion of the sample was routinely plated in blood agar, thioglycolate broth, or Sabouraud agar to rule out bacterial or fungal infection. The rest of the sample was submerged in a microcentrifuge tube with saline and sent together with the patient's contact lenses and cases to the laboratory at the University Institute of Tropical Diseases and Public Health of the Canary Islands; there it was cultured on 2% nonnutrient agar (NNA) plates and examined using an inverted microscope as previously described (16). Lenses were directly cultured in NNA and checked for amoebic growth. The contact lens cases were washed twice with 2 ml of sterile saline, and the saline was then filtered using a vacuum manifold sys...

show abstract

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Prognostic Factors Affecting Visual Outcome in Acanthamoeba Keratitis

Abstract: Objective-To identify clinical and demographic factors associated with a worse visual outcome in Acanthamoeba keratitis (AK).Design-Retrospective, case control study.

Cited by 119 publications

References 16 publications

Microbiological cure times in acanthamoeba keratitis

Microbiological cure times in acanthamoeba keratitis

Influence of Acanthamoeba Genotype on Clinical Course and Outcomes for Patients with Acanthamoeba Keratitis in Spain

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

Contact Info

Product

Resources

About