GROWTH CHARACTERISTICS OF CANDIDA ALBICANS ON PAGANO-LEVIN CULTURE MEDIUM* AUSTIN H. KUTSCHER, D.D.S., LUCILE SEGUIN, B.S., EDWARD V. ZEGARELLI, D.D.S., M.S., ROBIN M. RANKOW, D.D.S., M.D., JAMES MERCADANTE, D.D.S. AND JOHN D. PIRO, D.D.S. With the assistance of J. B. CAMPBELL AND HENRY PEARSON Recently, a nutrient agar, the Pagano-Levin Culture Medium (1—3), has been developed which is intended for use in the differential selective identification of Candida albicans organisms ob- tained from pathological specimens. The presence of a broad spectrum antibiotic incorporated in the medium also inhibits or suppresses concomitant bacterial growth. This medium contains a biologi- cal indicator system which is suggested as per- mitting simple, rapid, and convenient differentia- tion of Candida albicans organism colonies from those of other Candida species and saprophytic yeasts. This differentiation is made by visual in- spection of the color of the colony growing on the medium after from two to three days of incuba- tion at usual room temperature. Those colonies appearing cream colored or very faintly pink are tentatively identified as Candida albicans. Most species of Candida other than Candida albicans and most other saprophytic and pathogenic yeasts grow out as darker pink to dark red colonies. The major exception to this overall picture is the colony of Candida krusei which is white in color but which, upon comparison with those of Can- dida albicans, appears flat, dry, and non-glistening as opposed to the smooth, creamy, glistening tex- ture of the Candida albicans colony. Pagano-Levin Culture Medium is supplied ready for immediate use in vials containing ap- proximately two cc. of the solid nutrient agar in slant form. The nutrient composition of the Pa- gano-Levin Medium is very slightly modified from (fortified) but in all respects essentially simi- lar to Sabouraud's medium. The Pagano-Levin Medium also includes a tetrazolium compound (see below) and a relatively broad spectrum anti- * From the Departments of Dentistry and Bac- teriology, Francis Delafield Hospital, College of Physicians and Surgeons, Columbia University, New York, New York. Pagano-Levin Medium for this study was sup- plied by The Squibb Institute for Medical Re- search, New Brunswick, New Jersey. Received for publication November 15, 1958. 41 biotic, neomycin, not present in Sabouraud's me- dium (1). According to Pagano, Levin, and Trejo (1), the differentiating quality of the medium depends on the differing ability of various yeasts and fungi to reduce a tetrazolium compound included in the medium to insoluble, colored formizans; while Candid,a albicans does so either not at all or to a very limited extent. This study was undertaken to further investi- gate the growth characteristics on this medium of a group of 100 different strains of Candida albicans organisms previously isolated in the School of Dental and Oral Surgery of Columbia University, the Department of Mycology of the College of Physicians and Surgeons of Columbi University, the Departments of Bacteriology at the Francis Delafield Hospital, and St. Luke's Hospital, as well as a group provided by the Squibb Institute for Medical Research. It was hoped that this study would 1) evaluate the possibility and desirability of attempting a differential diagnosis upon a given specimen sub- mitted for culture in terms of the presence or ab- sence of Candida albicans through the use of the Pagano-Levin Culture Medium; and 2) to cast further light on the differences, peculiarities, and similarities of the growth and color characteris- tics of the various strains of Candida albicans which are to be expected on this medium. For purposes of color evaluation of the organ- isms at the varying time intervals included in our study, use was made of a specially prepared Color Shade Guide (see Figure 1) which contained 57 hand painted (in oil colors) plastic coated color chips ranging from white to red and leading off in arithmetic proportions from these basic colors to the yellows and blues. Upon the occasion of the evaluation of each culture at each time inter- val at which it was studied, the color chip shade guide was used to match the color of the colony as closely as possible. This color was then re- corded. All observations were made by fluorescent