Since 1958 Pagano-Levin medium (PLM) has been used as an aid in the identification of Candida albicans. However, no statistical analysis of its effectiveness based on large number of random human specimens has been reported. The present study compared PLM (now called Candida test) with Sabouraud's plus antimicrobials and Littman's ox-gall agar without antimicrobials. Of 500 random vaginal samples 24.8 were true positives, 71.9% were true negatives, 2.2% were false positives, and 1.2% were false negatives on PLM. If only samples identified as C. albicans were considered, 95.4% were true positives and 4.6% were false negatives. PLM did not inhibit C. albicans from the vagina. No one medium was found superior to the others for the purpose of isolating and identifying C. albicans. Of the five strains of C. parapsilosis, the only other Candida species isolated, all the samples grew on PLM but most were inhibited on Sabouraud's medium plus antimicrobials. Pagano, Levin, and Trejo (30) described a medium formulated to aid in differentiation of Candida albicans from other species of the genus based on development of color upon growth of yeasts on a medium containing 2,3,5-triphenyltetrazolium chloride. Candida spp. varied in reduction of tetrazolium. Most Candida spp. formed colored formazans, but C. albicans either did so slightly or not at all. With the optimum concentration of 2,3,5-triphenyltetrazolium chloride was 100,ug/ml (0.01%), C. albicans produced creamy-textured, white to pink colonies. Other Candida spp. produced dark reds with a creamy texture or a whitechalky colony. The medium also included neomycin to suppress bacteria. Though not cited by Pagano et al., Canizares and Shatin in 1951 (8) had used 2,3,5-triphenyltetrazolium chloride in dermatophyte culture media; 0.01% 2,3,5-triphenyltetrazolium chloride produced pink colonies of C. albicans with a white edge 14 days after inoculation. The medium has been generally referred to as Pagano-Levin medium (PLM). In 1970, E. R. Squibb and Sons called it "Candida test medium for fungi." Under the name Pagano-Levin medium there are many reports of its use (1,

Guinea pigs sensitized by repeated skin testing with potent, merthiolated coccidioidin, equal to Smith standard, exhibited erythema, edema, and an induration-like reaction to intradermal injection of the preparation. No statistically significant migration inhibition of peritoneal exudate macrophages from these animals was observed.