Wang H S, Zeimis R T, Roberts G D
J Clin Microbiol. 1977 Nov;6(5):445-9. doi: 10.1128/jcm.6.5.445-449.1977.
An evaluation of a rapid caffeic acid-ferric citrate paper disk test for the identification of Cryptococcus neoformans, using 474 isolates of yeasts and yeastlike organisms, showed that 96.6, 97.7, and 98.3% of 176 isolates of C. neoformans produced brown to dark-brown pigment on disks incubated for 6 h at room temperature, 30 degrees C, and 37 degrees C, respectively. All C. neoformans produced brown to dark-brown pigment within 24 h. However, nonspecific pigmentation was encountered at all temperatures of incubation with one isolate of Trichosporon cutaneum and, at room temperature only, with one isolate of C. luteolus after 6 h. Other genera of yeasts produced similar pigmentation after 24 h at all temperatures. The age of the cultures tested or the types of media used before testing did not significantly affect the ability of C. neoformans to produce pigmentation at 37 degrees C. A positive test may prove useful for presumptive identification of C. neoformans, but a negative reaction should not be used to rule out an identification of this yeast. Since a number of false-negative and false-positive tests occur, it is necessary to confirm, by other biochemical tests, the identification of all organisms suspected of being C. neoformans, to reduct the serious risk of missing or misidentifying this important pathogen.
利用474株酵母和类酵母生物分离株对用于鉴定新型隐球菌的快速咖啡酸 - 柠檬酸铁纸片试验进行评估，结果显示，176株新型隐球菌分离株中，分别在室温、30℃和37℃下孵育6小时的纸片上，有96.6%、97.7%和98.3%产生了棕色至深棕色色素。所有新型隐球菌在24小时内都产生了棕色至深棕色色素。然而，在所有孵育温度下，一株皮状丝孢酵母在孵育6小时后出现了非特异性色素沉着，在室温下，一株浅黄隐球菌在孵育6小时后也出现了非特异性色素沉着。其他酵母属在所有温度下孵育24小时后产生了类似的色素沉着。受试培养物的菌龄或测试前使用的培养基类型对新型隐球菌在37℃下产生色素沉着的能力没有显著影响。阳性试验可能有助于新型隐球菌的初步鉴定，但阴性反应不应被用于排除该酵母的鉴定。由于存在一些假阴性和假阳性试验，有必要通过其他生化试验来确认所有疑似新型隐球菌的生物体的鉴定，以降低漏检或误认这种重要病原体的严重风险。
