“Candida dubliniensis”的意思、由来-开放百科全书

Candida dubliniensis is a fungal opportunistic pathogen originally isolated from AIDS patients. It is also occasionally isolated from immunocompetent individuals. It is a dimorphic yeast{{Citation needed|date=November 2009}} of the genus Candida, very closely related to Candida albicans but forming a distinct phylogenetic cluster in DNA fingerprinting. It is most commonly isolated from oral cavities,^[1] and is also occasionally found in other anatomical sites.

Prevalence and epidemiology

Candida dubliniensis is cosmopolitan (found around the world), and has been described as a separate species in 1995.^[2] Retrospective studies have shown that previously it had been commonly identified as Candida albicans, with which C. dubliniensis is closely related and shares a number of characteristics.

One test for distinguishing C. dubliniensis from C. albicans, is laboratory culture of the organism at 42 °C. Most C. albicans strains grow at this temperature,^[3] whereas most C. dubliniensis isolates do not.^[2] There are also significant differences in the conditions that lead to the formation of chlamydospores between C. albicans and C. dubliniensis, although they are otherwise phenotypically very similar.^[2]

A European study of 2,589 isolates, that had originally been identified as C. albicans, revealed that 52 of them (2.0%) were C. dubliniensis. Most of these isolates were from oral or faecal specimens from HIV-positive patients, though one vaginal and two oral isolates were from healthy individuals.{{Citation needed|date=November 2009}} Another study in the United States surveyed 1,251 yeasts previously identified as C. albicans, and identified 15 isolates (1.2%) as C. dubliniensis. Most of these isolates were from immunocompromised individuals, such as AIDS, chemotherapy, or organ transplant patients.{{Citation needed|date=November 2009}} The majority of C. dubliniensis strains were recovered from respiratory, urine and stool specimens.{{Citation needed|date=November 2009}} The Memorial Sloan-Kettering Cancer Center also conducted several studies, both retrospective and prospective. In 974 germ-tube positive yeasts, 22 isolates (2.3%) from 16 patients were C. dubliniesis. All individuals were immunologically compromised with either malignancy or AIDS, and the isolates came from a variety of different sites. C. dubliniensis was also isolated from the mouths of 18% of patients with diabetes and who use insulin.^[4]

Antifungal susceptibility

In one study, all 20 C. dubliniensis isolates tested were susceptible to itraconazole, ketoconazole and amphotericin B.^[5]

Fluconazole

Many isolates of C. dubliniensis are sensitive to fluconazole. In one study, 16 of 20 isolates were sensitive to fluconazole, while four were resistant.^[5] It has been hypothesized that C. dubliniensis has the ability to rapidly develop resistance to fluconazole, especially in patients who are on long-term therapy.^[5]

Stable fluconazole resistance could be induced in vitro by subjecting sensitive strains to increasing concentrations of this antifungal. This resistance is mediated by a multidrug transporter that can be mobilized rapidly in vitro, on exposure to fluconazole.{{Citation needed|date=November 2009}}

Cases in America have also shown the emergence of fluconazole-resistant C. dubliniensis. Three isolates were discovered in Texas, two of which were resistant (MIC, 64 µg/mL), and one had dose-dependent susceptibility (MIC, 16 µg/mL). Among C. dubliniensis isolates in HIV+ patients in Maryland, most isolates were highly susceptible to fluconazole. A study of 71 isolates in Ireland, showed that both the fluconazole-resistant and susceptible strains were susceptible to itraconazole, amphotericin B, and 5-fluorocytosine (microdilution). They were also susceptible to experimental triazoles and voriconazole and echinocandin.{{Citation needed|date=November 2009}}

References

1. ^{{cite journal |last1=Gilfillan |first1=G. D. |last2=Sullivan |first2=D. J. |last3=Haynes |first3=K. |last4=Parkinson |first4=T. |last5=Coleman |first5=D. C. |last6=Gow |first6=N. A. R |authorlink6=Neil A. R. Gow |title=Candida dubliniensis: phylogeny and putative virulence factors |journal=Microbiology |volume=144 |issue=4 |year=1998 |pages=829–838 |pmid=9579058 |doi=10.1099/00221287-144-4-829}}
2. ^¹²{{cite journal |vauthors=Sullivan DJ, Westerneng TJ, Haynes KA, Bennett DE, Coleman DC | title=Candida dubliniensis sp. nov.: phenotypic and molecular characterization of a novel species associated with oral candidosis in HIV-infected individuals | journal=Microbiology | year=1995 | volume=141 | pages=1507–21 |pmid=7551019 | doi=10.1099/13500872-141-7-1507 | issue=7 }}
3. ^{{cite journal |author1=Kamiyama A |author2=Niimi M |author3=Tokunaga M |author4=. Nakayama H | title= Adansonian study of Candida albicans: intraspecific homogeneity excepting C. stellatoidea strains | journal=J Med Vet Mycol | year=1989 |volume=27 | pages=229–241 | doi=10.1080/02681218980000311 | pmid=2677300 | issue=4}}
4. ^{{cite journal |vauthors=Willis AM, Coulter WA, Sullivan DJ, Coleman DC, Hayes JR, Bell PM, Lamey PJ | year=2000 | title=Isolation of C. dubliniensis from insulin-using diabetes mellitus patients | journal=J Oral Pathol Med | volume=29 | issue=2 | pages=86–90 |pmid=10718404 | doi=10.1034/j.1600-0714.2000.290206.x }}
5. ^¹²{{cite journal |vauthors=Moran GP, Sullivan DJ, Henman MC, McCreary CE, Harrington BJ, Shanley DB, Coleman DC | title=Antifungal drug susceptibilities of oral Candida dubliniensis isolates from human immunodeficiency virus (HIV)-infected and non-HIV-infected subjects and generation of stable fluconazole-resistant derivatives in vitro | journal=Antimicrob. Agents Chemother.|date=March 1997| volume=41 | issue=3 | pages=617–23 | pmid=9056003 | pmc=163761| doi=10.1128/AAC.41.3.617 }}

Prevalence and epidemiology

Antifungal susceptibility

Fluconazole

References

External links