Use of the Membrane Filtration Technique and Staib Agar* for the Detection of Cryptococcus neoformans in the Urine of AIDS Patients —A Contribution to Diagnosis, Therapy and Pathogenesis of Cryptococcosis

Abstract

For the cultural control of Cryptococcus neoformans (Cr.n.), among the routinely examined standard specimens like CSF, sputum, blood, etc., urine earns special attention. The combination of membrane filtration technique (MFT) and Staib agar for the detection of Cr.n. from body fluids as described by Staib in 1963 was used for the cultural isolation of Cr.n. from urine of AIDS patients. In 3 examplary cases the diagnostic significance of this method could be demonstrated: The brown colour effect (BCE) of Cr.n. of a single CFU, as well as in colonies growing with a high density, was produced on average within 3-5 d/26 degrees C. The method was found to be useful for the evaluation of antimycotic therapy. One example of the survival of a few CFUs of Cr.n. under treatment with fluconazole as compared to the efficacy of therapy with amphotericin B + flucytosine, and one example of a re-emergence of Cr.n. in the urogenital tract after a too short duration of treatment with amphotericin B + flucytosine are shown. For the exclusion of the survival of single CFUs of Cr.n. in the urogenital tract of males, quantities up to 1 l of urine for the combination of MFT and Staib agar are proposed. As a secondary observation, it was found that this diagnostic combination in addition to its primary purpose, can serve to detect the metabolic end products of the human body present in urine which may influence capsule formation of Cr.n. neoformans.