Laboratory detection of ocular microsporidia

Purpose. Ocular Microsporida are opportunistic, obligate intracellular parasite, recovered from HIV+/AIDS patients. Rapid laboratory techniques are required for confirmation, to determine prevalence rates and to design efficacy treatment modalities.. Methods. From Jan. 1990-June 1995, 14 patients presenting with superficial punctate keratitis suggestive of microsporidial keratitis were scrapped or biopsied and sent to the laboratory for evaluation. Medical records were examined to determine predisposing factors Results. All patients were diagnosed with AIDS or were HIV+ (mean CD4 counts = 34). Most common ocular complaints included decreased vision (71%), or foreign body sensation (43%). Other opportunistic infections: CMV retinitis (57%) and Toxoplasma gondii retinitis (14%). No patient complained of diarrhea. Smears and impression cytology filters were stained with gram, modified giemsa or calcofluor white. In giemsa and gram stain preparations, under oil immersion, Microsporida appeared as small (1-2 um), intracellular, oval dark staining bodies. Bright, apple green fluorescence of the outer chitin surface was seen with calcofluor white. Combination of modified giemsa with impression cytology best detected and preserved the morphology of these delicate protozoan. Seventy-nine percent of patients were treated with flagyl; 91% showed short term improvement in symptoms/and or visual acuity. Conclusions. Ocular Microsporida can be rapid detected using routine microbiological stains. Flagyl may alleviate acute symptoms.