Isolation and rapid identification of yeasts from compromised hosts.
In order to improve the isolation and identification of yeasts in a cancer research hospital, a protocol was developed utilizing an improved blood culture methodology and a four-test schema for rapid yeast identification. The blood culturing technique, based upon centrifugation, has shown a ten-fold increase in isolation of fungi from blood and has provided for: quantitation or organisms, unlimited selection of media and atmospheres for primary culturing, and a 1:200 dilution of microorganisms away from serum antimicrobial factors and antibiotics. The four-test schema, which may be adapted for the identification of any unknown yeast in pure culture, consists of a dye pour plate auxanogram (DPPA), Tween 80-Oxgall-Caffeic acid (TOC), a rapid nitrate-reductase test (swab test) and Urea 'R' Broth. Using this protocol, over 95% of the clinical isolates received were correctly identified within 24 hours and 100% by 48 hours. By using DPPA, a 14 sugar assimilation pattern for each isolate was determined within 12 to 16 hours; and in some cases, as little as 6 hours. Growth on TOC yielded one of the following results: (1) Candida albicans and Candida stellatoidea sequentially produced germ tubes and chlamydospores in 3 hours and 24 hours, respectively; (2) Cryptococcus neoformans produced a brown pigment specific for its identification in 12 hours or less. The swab test gave results on nitrate utilization in less than 15 minutes and urease was detected within 4 hours.
D001769:Blood / Q000382:microbiology; D050260:Carbohydrate Metabolism; D003428:Cross Infection / Q000175:diagnosis*; D003470:Culture Media; D003937:Diagnosis, Differential; D006801:Humans; D008828:Microbiological Techniques; D009181:Mycoses / Q000175:diagnosis*; D009566:Nitrates / Q000378:metabolism; D014510:Urease / Q000096:biosynthesis; D015003:Yeasts / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism
D003470:Culture Media; D009566:Nitrates; D014510:Urease