Disseminated cryptococcosis in an AIDS patient caused by a canavanine-resistant strain of Cryptococcus neoformans var. grubii.
A case of disseminated cryptococcosis caused by Cryptococcus neoformans var. grubii is presented in a male diabetic who had AIDS. The diagnosis was based upon the isolation and identification of the aetiological agent from a lymph-node biopsy, cerebrospinal fluid and sputum. The isolate formed spherical, encapsulated yeast cells, produced cherry-brown colonies on niger-seed agar, grew on canavanine-glycine-bromothymol blue (CGB) medium, changing its colour from greenish yellow to blue, and hydrolysed urea weakly in the presence of 100 microM EDTA. The strain was unable to assimilate D-proline and, serologically, it was untypable. The identity of the isolate as C. neoformans var. grubii, serotype A, possessing a mating-type allele A alpha, was confirmed by crossing with standard laboratory test strains and by performing PCR with the mating-type alpha allele-specific primer of the STE12 gene and with serotype (A and D)- and mating type (a and alpha)-specific primers of the STE20 gene. To the best of our knowledge, this is the first report of disseminated cryptococcosis in an AIDS patient caused by a canavanine-resistant strain of C. neoformans var. grubii, serotype A, possessing mating type allele A alpha; the strain is probably a hybrid. The report suggests that, in the absence of a clear-cut serotyping result, a positive CGB reaction alone is not sufficient for intervarietal discrimination and additional confirmatory evidence is required.
Khan
Z U
ZU
Department of Microbiology, Faculty of Medicine, Kuwait University, Kuwait 2Infectious Diseases Hospital, Ministry of Public Health, Kuwait 3Department of Biology, McMaster University, Hamilton, Ontario, Canada.
Al-Anezi
A A
AA
Department of Microbiology, Faculty of Medicine, Kuwait University, Kuwait 2Infectious Diseases Hospital, Ministry of Public Health, Kuwait 3Department of Biology, McMaster University, Hamilton, Ontario, Canada.
Chandy
R
R
Department of Microbiology, Faculty of Medicine, Kuwait University, Kuwait 2Infectious Diseases Hospital, Ministry of Public Health, Kuwait 3Department of Biology, McMaster University, Hamilton, Ontario, Canada.
Xu
J
J
Department of Microbiology, Faculty of Medicine, Kuwait University, Kuwait 2Infectious Diseases Hospital, Ministry of Public Health, Kuwait 3Department of Biology, McMaster University, Hamilton, Ontario, Canada.
D017088:AIDS-Related Opportunistic Infections / Q000150:complications / Q000382:microbiology*; D000163:Acquired Immunodeficiency Syndrome / Q000150:complications*; D000666:Amphotericin B / Q000627:therapeutic use; D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002172:Canavanine / Q000494:pharmacology*; D003453:Cryptococcosis / Q000150:complications* / Q000188:drug therapy / Q000382:microbiology; D003455:Cryptococcus neoformans / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification* / Q000502:physiology; D003920:Diabetes Mellitus; D025141:Drug Resistance, Fungal; D017809:Fatal Outcome; D015725:Fluconazole / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged
D000935:Antifungal Agents; D002172:Canavanine; D000666:Amphotericin B; D015725:Fluconazole