April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
Effect Of Microaerophilic Environments On The Growth Of Selected Acanthamoeba Isolates
Author Affiliations & Notes
  • Scott Schatz
    Optometry, Midwestern University, Glendale, Arizona
  • Ivan Cometa
    Biological Sciences, California State University at Fresno, Fresno, California
  • Andrew Rogerson
    Biological Sciences, California State University at Fresno, Fresno, California
  • Footnotes
    Commercial Relationships  Scott Schatz, AMO (C); Ivan Cometa, None; Andrew Rogerson, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 5806. doi:
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      Scott Schatz, Ivan Cometa, Andrew Rogerson; Effect Of Microaerophilic Environments On The Growth Of Selected Acanthamoeba Isolates. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5806.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : An increase in the incidence of Acanthamoeba keratitis warrants studies to provide insights into the factors which may influence the pathogenicity of Acanthamoeba isolates. We studied the effect of reduced ambient oxygen availability on the growth of 11 environmental and clinical Acanthamoeba isolates.

Methods: : Eleven environmental and clinical Acanthamoeba strains maintained as stock cultures held at California State University Fresno were utilized in the study. Two of the isolates were recently obtained from anaerobic sediments on the California State University Fresno (CSUF) campus. All of the isolates except the two from CSUF were molecularly typed and categorized. All Acanthamoeba strains were cultured on non-nutrient agar plates streaked with prey bacterium E. coli. All isolates were grown under identical light, temperature and nutrient regimes and under atmospheric and reduced ambient oxygen levels. The effect of atmospheric oxygen levels vs microaerophilic conditions (approx 10% oxygen) on the migration of acanthamoebae on agar was compared and utilized as a reliable index of growth. Distance traveled after incubation from point of inoculation was recorded

Results: : All the isolates tested grew under high and low ambient oxygen conditions. However, most of the isolates grew significantly faster (T-test, p<0.05) under low oxygen conditions. This was true of all the T4 genotypes and the two microaerophilic isolates. The T4 group included 4 known pathogens isolated from infected corneas.

Conclusions: : The reasons why certain Acanthamoeba isolates infect the cornea are unclear. It may be related to strain or species differences. Infection of the cornea may be related to inducible gene characteristics secondary to changes in ambient conditions such as reduced ambient oxygen availability. This might occur secondary to overnight contact lens wear particularly in the closed eye condition. Additionally, upregulation of corneal epithelium intracellular biochemical pathways such as the upregulation of matrix metallic proteinases (MMP’s) causing the loosening of ocular surface layer tight junctions or an extracellular upregulation of the alternate complement cascade with a similar outcome may allow for the opportunistic infection of the cornea. Poor contact lens hygiene practices among contact lens wearers seem to be a major contributing factor in the etiology of Acanthamoeba induced Amoebic Keratitis (Seal et al. 1999).

Keywords: Acanthamoeba • cornea: clinical science • microbial pathogenesis: experimental studies 

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