Morphological characteristics in corneal smear of acanthamoeba keratitis

Objective To study the morphological characteristics in corneal smear of acanthamoeba keratitis. Methods Experimental study. From May 1991 to December 2007, in Department of Microbiology, Beijing Institute of Ophthalmology, Beijing Tongren Hospital, 159 cases with acanthamoeba keratitis were analyzed for the laboratory results and clinical data. Giemsa's stained smear and wet-mount preparation of 159 cases were observed, all the results of cytology be photographed as the records. Results Among the 159 cases with acanthamoeba keratitis, 131 patients (82.4%) were positive on smear, and 110 cases (69.2%) were positive in culture of amoeba. The detection positive rate of smear was apparently higher than culture. Typical trophozoites, pre-encystment trophozoites, mature cysts and empty cysts could be observed by smear. So it is an important method for the clinical diagnosis. The edema and dissolved corneal epithelial cells, exudate cells, arthrospore or chlamydoconidium of mycelial fungus, vacuolus, lipid droplet and medicine crystallization should be differentiated with the pathogen. The movement of trophozoites could mainly be observed through wet-mount preparation. Conclusion The detection of typical features of trophozoites, pre-encystment trophozoites, mature cysts and empty cysts by corneal smear is important for the etiological diagnosis of acanthamoeba keratitis. Key words: Acanthamoeba keratitis; Acanthamoeba; Cytodiagnosis; Staining and labeling