March 2012
Volume 53, Issue 14
ARVO Annual Meeting Abstract  |   March 2012
Growth Of Acanthamoeba On Contact Lens Storage Case Bacteria And Their Survival Within The Cyst Stage
Author Affiliations & Notes
  • Anthony Lam
    Corneal R & D Microbiology, Abbott Medical Optics, Santa Ana, California
  • Simon Kilvington
    Corneal R & D Microbiology, Abbott Medical Optics, Santa Ana, California
  • Footnotes
    Commercial Relationships  Anthony Lam, None; Simon Kilvington, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 6172. doi:
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      Anthony Lam, Simon Kilvington; Growth Of Acanthamoeba On Contact Lens Storage Case Bacteria And Their Survival Within The Cyst Stage. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6172.

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

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Purpose: : Acanthamoeba keratitis is a rare but potentially blinding infection with contact lens (CL) wearers accounting for 90% of cases. CL storage cases (CLSC) can become rapidly and persistently contaminated with bacteria and so provide a food source for Acanthamoeba. The comparative rates of Acanthamoeba trophozoite growth on CLSC bacterial isolates and their survival within the resistant cyst stage of the organism was investigated.

Methods: : Gram negative bacteria from CLSC and Escherichia coli (ATCC 8739) were seeded on non-nutrient agar plates and inoculated with cysts of A. castellanii (ATCC 50370) or A. polyphaga (ATCC 30461). Plates were incubated at 28ºC and the rate of trophozoite feeding and migration (following excystment) across the plates measured over 14 d. A. castellanii cysts, formed on the plates after 7 d, were harvested and incubated in 1N HCl for 24 hr to kill free bacteria, trophozoites and immature but not mature cysts. Cysts were washed with deionised water and incubated in a broth medium at 28ºC for up to 7 d. Here, viable cysts hatch and the emergent trophozoites release surviving bacteria which multiply in the medium. In other studies, the co-cultured, acid treated cysts were exposed to CL disinfectant solutions: MPS-1 (PQ1 + PHMB) and MPS-2 (PQ1 + MAPD, 6 ppm) for 24 hr before excystment.

Results: : A. castellanii trophozoites fed and replicated with equal migration(>75 mm) after in 6-7 d with all strains of Achromobacter spp. (2), Delftia spp. (3), Stenotrophomonas maltophilia (3), E. coli (1), Serratia marcescens (1), Elizabethkingia spp. (2), Sphingobacterium spiritivorum (1) and Chryseobacterium indologenes (1). However, with one strain of C. indologenes (HD3C) growth was poor and required 12 d of incubation. For A. polyphaga, reduced growth rates were observed with S. marcescens (12 d), one strain of Achromobacter sp. (little or no growth by 14 d) and C. indologenes, HD3C (11 d). Achromobacter sp., S. maltophilia, E. coli and S. marcescens survived within A. castellanii cysts following HCl treatment and subsequent disinfection with MPS-1 and MPS-2.

Conclusions: : CLSC bacterial contaminants can support the growth of Acanthamoeba and may serve as a food source for the organism in the development of amoebic keratitis. Survival within Acanthamoeba cysts may afford bacteria protection from disinfection and aid environmental dispersal and colonisation. The role of bacterial co-infection in the pathogenesis of Acanthamoeba keratitis warrants investigation.

Keywords: Acanthamoeba • contact lens 

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