Early diagnosis of Exophiala CAPD peritonitis by 18S ribosomal RNA gene sequencing and its clinical significance.
Phenotypic identification of fungi in clinical microbiology laboratories is often difficult and late, especially for slow growing and rarely encountered fungi. We describe the application of 18S ribosomal RNA (rRNA) gene sequencing in the early diagnosis of a case of Exophiala peritonitis. A yeast-like fungus was isolated from the dialysate fluid of a 66-year-old man undergoing continuous ambulatory peritoneal dialysis. It grew slowly after 12 days of incubation to yield mature cultures to permit recognition of microscopic features resembling those of Exophiala, a dematiacerous mold. 18S rRNA gene sequencing provided results 12 days earlier than phenotypic identification and revealed 15 base difference (0.9%) between the isolate and Exophiala sp. strain GHP 1205 (GenBank Accession no. AJ232954), indicating that the isolate most closely resembles a strain of Exophiala species. The patient responded to 4 weeks of intravenous amphotericin B therapy. Early identification of the fungus was important for the choice of anti-fungal regimen. As opportunistic fungal infections in immunocompromised patients are globally emerging problems, the development of molecular techniques for fungal identification is crucial for early diagnosis and appropriate treatment.
Lau
Susanna K P
SK
Department of Microbiology, The University of Hong Kong, Hong Kong, China.
Woo
Patrick C Y
PC
Chiu
Siu-kau
SK
Leung
Kit-wah
KW
Yung
Raymond W H
RW
Yuen
Kwok-yung
KY
D000368:Aged; D000666:Amphotericin B / Q000008:administration & dosage; D001483:Base Sequence; D015314:Dialysis Solutions; D005093:Exophiala / Q000187:drug effects / Q000302:isolation & purification*; D020459:Genes, rRNA / Q000235:genetics; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000628:therapy; D008297:Male; D008969:Molecular Sequence Data; D009181:Mycoses / Q000175:diagnosis* / Q000188:drug therapy; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects; D010538:Peritonitis / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology; D016133:Polymerase Chain Reaction / Q000379:methods; D012337:RNA, Ribosomal, 18S / Q000032:analysis / Q000235:genetics*; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D015314:Dialysis Solutions; D012337:RNA, Ribosomal, 18S; D000666:Amphotericin B