To study the prevalence, phenotype and genotype of clinical isolated Cryptococcus neoformans, the cultures in Mycology unit, King Chulalongkorn Memorial Hospital from August 1997 to July 1999 were recruited. The microscopic morphology examination using India-ink preparation, biochemical identification kit, API 20CAUX (BioM’erieux, France), Urease test, phenol oxidase test were performed to obtain the genus and species. Their varieties and serotypes were examined by canavanine-glycine medium and CrytoCheck (latron, Japan) respectively. The polymorphism in the hypervariable region using minisatellite M13 primer in the polymerase chain reaction or so celled PCR-RAPD profile was used for genotypic study. A total of six hundred thirty eight strains from cryptococcal meningitis patients were isolated from cerebrospinal fluid (97%) and others (3%). Most patients whom the specimens were sent were suffered from HIV infection (50.5% of the available data, the total data was available only 53%). In contrast, only four non-HIV infected patients whom physicians diagnosed as SLE were included. The phenotype and serotype results revealed that all these cultures were C.neoformans var. neoformans serotype A (C.grubil). Further, one hundred forty strains were used to investigate for the PCR-RAPD profile. Among these strains, three types of the profiles (96.5%, 2.8%, and 0.7%) were found. The major type were indistinguished from the VNI genetype from the report of Meyer et al. Another two types bearing the 2 – 3 intense bands different from the VNI type. The polymorphic profiles were found in 3 strains isolated from 1/5 cases (HIV infected patients) whom admitted 2 – 3 episodes and 1 strain from 1/3 cases (SLE patients). The genotypic profile of these four strains were the same and different from the major type. The last profile was from the individual isolate from HIV-infected patient. In conclusion, the result of phenotype and genotype was corresponse to each other but the later using PCR-RAPD method revealed more degree of strain discrimination. However, to confirm this discrimation with other molecular technique is suggested.
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พันธุศาสตร์จุลชีพ
เชื้อรา
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Thailand and ASEAN Information Center (6th Floor) : Chula Collection
