Rhodamine-auramine O versus Kinyoun-carbolfuchsin acid-fast stains for detection of Cryptosporidium oocysts.

The rhodamine-auramine O stain was compared with the Kinyoun carbolfuchsin acid-fast stain for detection of Cryptosporidium oocysts in samples from patients infected with the human immunodeficiency virus (HIV). A total of 283 fecal specimens from HIV-infected patients were examined for the presence of Cryptosporidium oocysts. Duplicate smears of the fecal concentrates, prepared by the formalin ethyl acetate procedure, were stained by the Kinyoun carbolfuchsin and fluorescent rhodamine-auramine O acid-fast methods. The Kinyoun stain detected 13 positive specimens, while the rhodamine-auramine O stain detected 14 positive specimens. The average time required to survey a stained smear was 2.5 minutes with the fluorescent method, compared with 6.0 minutes with the Kinyoun technique. The rhodamine-auramine O stain is a dependable and efficient method of examining fecal smears for the presence of Cryptosporidium oocysts in a high-risk population.