DIAGN MICROBIOL INFECTDIS 521 1989;12:521-523 NOTES Rapid Identification of Candida albicans Using 4-Methylumbelliferyl N-acetyl- -galactosaminide Maurice T. Dalton, David J.M. Haldane, and June MacDonald Rapid identification of Candida albicans is performed mainly by the germ-tube test. However, recent reports have suggested that up to 5% of C. albicans species can give false negative results. We describe the use of 4-Methylumbelliferyl N-acetyl- ~-D-galactosaminid~ (4-MAG) conjugate as an alternative to the germ-tube test. Our results indicate that, in comparison to the germ-tube test, the 4-MAG test has a sensitivity of 100% and a specificity of 92%. Candida tropicalis can give false- positive results, and that a further screening test is required to identify this species. Problems reading end-points were not encountered. Candida albicans continues to be the most commonly recovered yeast in clinical laboratories. The more frequent use of immunosuppressing therapies and the prolonged survival time of immunocompro- mised hosts promotes opportunities for C. albicans as a major primary and opportunistic pathogen. Fur- thermore, the widespread use of broad spectrum antibiotics has also played a part in raising the clin- ical profile of candida infections (Muenier-Carpenter et al., 1981; Horant et al., 1988). Rapid presumptive identification of C. albicans has been based on the demonstration of germ tubes fol- lowing incubation at 35°C for 4 hr in pooled human or animal serum (Mackenzie, 1962). The use of com- mercial pooled human serum is now considered by many to be hazardous, and, in addition, up to 5% of C. albicans isolates have been reported as germ- tube negative (Perry and Miller, 1988). From the Departmentsof Microbiology, VictoriaGeneralHos- pital and DalhousieUniversity,Halifax,Nova Scotia, Canada. Address reprint requests to: Maurice T. Dalton, Department of Microbiology,VictoriaGeneral Hospital, Halifax,B3H 1V8, Nova Scotia, Canada. Received March 27, 1989; revised and accepted August 8, 1989. © 1989 Elsevier Science PublishingCo., Inc. 655 Avenue of the Americas, New York, NY 10010 0732-8893/89/$03.50 Bobey and Ederer (1981) and Perry and Miller (1988) previously indicated the hydrolysis product of 4-Methylumbelliferyl N-acetyl-~-D-galactos- aminide (4-MAG) conjugate is 4-Methylumbell- iferone, which produces a pale blue fluorescence when excited by a 365 nmol UV light source. 4-MAG is hydrolysed by either preformed or recently formed ~-D-galactos-aminidases present in C. albicans. Perry and Miller (1988) recently suggested that this test may be a useful alternative to the germ-tube test. We report here a comparison of the germ-tube test and 4-MAG breakdown by 292 clinical isolates of yeasts in our laboratory. Two hundred three consecutive yeasts recovered from clinical specimens and 92 clinical yeast isolates previously identified by the API 20C ® System (An- alytab Products, Plainsview, New York) were ex- amined by both the germ-tube test and the 4-MAG test. Stock cultures and fresh isolates were first sub- cultured onto 5% sheep blood agar (B.B.L., Cock- eysville, Maryland) for purity testing. The germ-tube test was performed by making a dilute suspension of yeast with pooled human serum (Difco, Detroit, Michigan), in borosilicate tubes 13 mm x 100 mm (Johns Scientific, Toronto, Ontario), using a sterile Pasteur pipette. The suspension was incubated at