Coccidians

Cyclospora cayetanensis. Oocysts in fecal smear (acid-fast stain, oil immersion). Oocysts of this organism stain variably with acid-fast stain; some do not stain at all but appear as glassy, wrinkled spheres, others take a partial pink stain, and still others will stain red. This acid-fast variability helps differentiate it from Cryptosporidium parvum, which is smaller and stains consistently pink to red.