Morphological Features of Acanthamoeba Causing Keratitis Contaminated from Contact Lens Cases
Usa Lek-Uthai DrPH*, Rangsima Passara MSc**, Kosol Roongruangchai MD, MSc***
Affiliation : * Department of Parasitology and Entomology, Faculty of Public Health, Mahidol University, Bangkok, Thailand **Faculty of Graduate Studies, Mahidol University, Bangkok, Thailand ***Department of Parasitology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : To study the morphological characteristics of genus Acanthamoeba which is an opportunistic
organism associated with wearing contact lenses that the biofilm phenomenon in contact lens cases contained
Acanthamoeba causing keratitis by conventional culture technique.
Material and Method: A total of 150 contact lens cases were biofilm scraped in March till September 2007, at
an institution in Nakhornpathom Province, Thailand. The ‘gold standard’ culture technique was used for
the excystation growth development observation. Cysts of Acanthamoeba spp. contained 50 microlitres of
Escherichia coli and contact lens solution were incubated and observed for the presence of cysts and/or
trophozoites for 12 days. An infected slide was stained with giemsa solution and other non-stained and non-
fixed slides were carried out for morphological characteristics study by different microscopes.
Results : The prevalence of Acanthamoeba spp. in scraping of contact lens cases was 6.7% (10/150). These
Acanthamoeba isolates at temperature around 37OC were consisted of all three groups, which in summary; the
average diameter of cysts in Astronyxids (group I) was relatively large. They were > 18 micrometers, while
those of Polyphagids (group II) and Culbertsonids (group III) were < 18 micron. The typical morphology of
Acanthamoeba trophozoites moving freely in water were recognized by the presence of lobopodium and
acanthopodia within 12 observed days. The average size of Acanthamoeba trophozoites was in the range of
12-45 micron. Three different images of cyst were feature studied.
Conclusion : Three Acanthamoeba groups by biofilm scraping from contact lens cases should be differentiated.
Morphological characteristics cysts and trophozoites should be confirmed. In addition, to improve contact
lens wearer education, compliance with contact lens cases, hygiene recommendations and regular disposal of
contact lens cases might help to solve contact lens cases.
Keywords : Acanthamoeba keratitis, Contact lens cases, Morphological features
