Field's stain - a rapid staining method for Acanthamoeba spp.

Acanthamoeba sp. is a free-living amoeba known to cause chronic central ner vous system infection or eye infection in humans. Many cases remain undetec ted for want of a good detection system. We report for the first time a rap id staining method to facilitate the identification of Acanthamoeba sp. usi ng the modified Field's staining technique. A. castellanii, which was used in the present experiment, is maintained in our laboratory in mycological p eptone medium (Gibco). The cultures were pooled together and smears were ma de on glass slides for staining purposes. Different types of stains such as Field's stain? modified Field's stain, Wright's stain, Giemsa stain, Ziehl -Neelsen stain, and trichrome stain were used to determine the best stain f or the identification of this amoeba. The concentration of various stains a nd the duration of staining were varied to provide the best color and contr ast for each stain. Acanthamoeba was also obtained from the brain of experi mentally infected mice and was stained with various stains as mentioned abo ve to determine the best stain for use in identifying the presence of this parasite in experimentally infected animals. The modified Field's stain giv es a very good color contrast as compared with other stains. Furthermore, i t takes only 20 s to be carried out using the least number of reagents, mak ing it suitable for both laboratory and field use.