scholarly journals 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.

1997 ◽  
Vol 41 (3) ◽  
pp. 617-623 ◽  
Author(s):  
G P Moran ◽  
D J Sullivan ◽  
M C Henman ◽  
C E McCreary ◽  
B J Harrington ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amphotericin B ◽  
Oral Candidiasis ◽  
Antifungal Drugs ◽  
Candida Dubliniensis ◽  
Fluconazole Resistance ◽  
Immunodeficiency Virus ◽  
Fluconazole Resistant ◽  
Hiv Negative

Candida dubliniensis is a recently described species of Candida associated with oral candidiasis in human immunodeficiency virus (HIV)-infected individuals. Nineteen oral isolates of C. dubliniensis recovered from 10 HIV-positive and 4 HIV-negative individuals and one vaginal isolate from an additional HIV-negative subject were assessed for fluconazole susceptibility by broth microdilution (BMD), hyphal elongation assessment, and Etest. The susceptibilities of these 20 isolates to itraconazole and amphotericin B and of 10 isolates to ketoconazole were also determined by BMD only. Sixteen of the C. dubliniensis isolates were susceptible to fluconazole (MIC range, 0.125 to 1.0 microgram ml-1), and four (recovered from two AIDS patients) were fluconazole resistant (MIC range, 8 to 32 micrograms ml-1). Fluconazole susceptibility data obtained by hyphal elongation assessment correlated well with results obtained by BMD, but the corresponding Etest MIC results were one to four times higher. All of the isolates tested were found to be sensitive to itraconazole, ketoconazole, and amphotericin B. Sequential exposure of two fluconazole-sensitive (MIC, 0.5 microgram ml-1) C. dubliniensis isolates to increasing concentrations of fluconazole in agar medium resulted in the recovery of derivatives which expressed a stable fluconazole-resistant phenotype (BMD-determined MIC range, 16 to 64 micrograms ml-1), even after a minimum of 10 consecutive subcultures on drug-free medium and following prolonged storage at -70 degrees C. The clonal relationship between the parental isolates and their respective fluconazole-resistant derivatives was confirmed by genomic DNA fingerprinting and karyotype analysis. The results of this study demonstrate that C. dubliniensis is inherently susceptible to commonly used antifungal drugs, that fluconazole resistance does occur in clinical isolates, and that stable fluconazole resistance can be readily induced in vitro following exposure to the drug.

scholarly journals Susceptibility of Candida dubliniensis to Salivary Histatin 3

2003 ◽  
Vol 47 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Deirdre H. Fitzgerald ◽  
David C. Coleman ◽  
Brian C. O'Connell
Keyword(s):  
Reference Strain ◽  
Therapeutic Potential ◽  
Oral Candidiasis ◽  
Human Saliva ◽  
Antifungal Drugs ◽  
Candida Dubliniensis ◽  
Immunodeficiency Virus ◽  
Fluconazole Resistant ◽  
Different Strains

ABSTRACT Candida dubliniensis is a recently described Candida species associated with oral candidiasis in human immunodeficiency virus (HIV)-infected patients and patients with AIDS. The majority of C. dubliniensis clinical isolates tested to date are susceptible to the commonly used antifungal drugs, including fluconazole, ketoconazole, itraconazole, and amphotericin B. However, the appearance of fluconazole-resistant C. dubliniensis strains in this patient group is increasing. Histatins are a family of basic histidine-rich proteins present in human saliva which have therapeutic potential in the treatment of oral candidiasis. The mechanism of action of histatin is distinct from that of commonly used azole and polyene drugs. Characterization of the antifungal activity of histatin has mainly been carried out using C. albicans but it is also effective in killing C. glabrata and C. krusei. Here we report that C. dubliniensis is also susceptible to killing by histatin 3. The concentration of histatin 3 giving 50% killing (the IC50 value) ranged from 0.043 to 0.196 mg/ml among different strains of C. dubliniensis. The least-susceptible C. dubliniensis strain, P9224, was found to internalize histatin at a lower rate than the C. albicans reference strain CA132A. The dissociation constant (Kd ) for the least-susceptible strain (C. dubliniensis 9224) was ninefold higher than that for the C. albicans reference strain. These results suggest that histatin 3 may have potential as an effective antifungal agent, particularly in the treatment of oral candidiasis in HIV-infected patients and patients with AIDS in which resistance to the commonly used antifungal drug fluconazole has emerged.

scholarly journals Effect of antimycotic agents on the activity of aspartyl proteinases secreted by Candida albicans

2003 ◽  
Vol 52 (3) ◽  
pp. 247-249 ◽  
Author(s):  
Martin Schaller ◽  
Nikola Krnjaic ◽  
Markus Niewerth ◽  
Gerald Hamm ◽  
Bernhard Hube ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Amphotericin B ◽  
Proteinase Inhibitors ◽  
Inhibitory Effect ◽  
Antifungal Drugs ◽  
Immunodeficiency Virus ◽  
Antimycotic Agent ◽  
Pepstatin A ◽  
Aspartyl Proteinases

The inhibitory effect of human immunodeficiency virus (HIV) proteinase inhibitors amprenavir and saquinavir and antifungal agents terbinafine, ketoconazole, amphotericin B and ciclopiroxolamine on aspartyl proteinases (Saps) secreted by Candida albicans was tested in an in vitro spectophotometric assay. As expected, both HIV proteinase inhibitors showed a significant inhibitory effect on Sap activity, which was comparable to that of the classical aspartyl proteinase inhibitor pepstatin A (P < 0.001). Antifungal drugs such as ketoconazole, terbinafine and amphotericin B had no, or only minor, inhibitory effects on proteolytic activity. In contrast, a significant reduction in Sap activity could be demonstrated during treatment with the antifungal agent ciclopiroxolamine (P < 0.001). These results point to a multiple effect of this antimycotic agent and might explain the reduced adherence of C. albicans to human epithelial cells at subinhibitory doses.

scholarly journals Recovery of Candida dubliniensis from Non-Human Immunodeficiency Virus-Infected Patients in Israel

2000 ◽  
Vol 38 (1) ◽  
pp. 170-174
Author(s):  
Itzhack Polacheck ◽  
Jacob Strahilevitz ◽  
Derek Sullivan ◽  
Samantha Donnelly ◽  
Ira F. Salkin ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Pcr Primers ◽  
Candida Dubliniensis ◽  
Upper Respiratory Tract ◽  
Specific Pcr ◽  
Immunodeficiency Virus ◽  
Dark Green ◽  
Green Coloration ◽  
Urine Specimens ◽  
Hiv Negative

ABSTRACT Candida dubliniensis is a recently discovered yeast species principally associated with carriage and disease in the oral cavities of human immunodeficiency virus (HIV)-infected individuals. To date the majority of isolates of this species have been identified in Europe and North America. In this study, five Candida isolates recovered from separate HIV-negative hospitalized patients in Jerusalem, Israel, were presumptively identified as C. dubliniensis on the basis of their dark green coloration when grown on CHROMagar Candida medium. Their identification was confirmed by a variety of techniques, including carbohydrate assimilation profiles, absence of growth at 45°C, positive reaction with C. dubliniensis -specific antibodies as determined by indirect immunofluorescence analysis, and positive amplification with C. dubliniensis -specific PCR primers. All five strains were shown to be susceptible to a range of antifungal agents, including fluconazole. One of the five isolates was recovered from urine specimens, while the remaining four were recovered from upper respiratory tract and oral samples. While none of the patients was HIV positive, all were receiving broad-spectrum antibacterials at the time isolates of C. dubliniensis were obtained from clinical specimens. This study describes the first isolates of C. dubliniensis from the Middle East and confirms that this yeast can be associated with carriage and infection in the absence of HIV infection.

scholarly journals Increased mRNA levels of ERG16, CDR, and MDR1 correlate with increases in azole resistance in Candida albicans isolates from a patient infected with human immunodeficiency virus.

1997 ◽  
Vol 41 (7) ◽  
pp. 1482-1487 ◽  
Author(s):  
T C White
Keyword(s):  
Human Immunodeficiency Virus ◽  
Candida Albicans ◽  
Abc Transporter ◽  
Genetic Alterations ◽  
Antifungal Drugs ◽  
Cross Resistance ◽  
Mrna Levels ◽  
Fluconazole Resistance ◽  
Immunodeficiency Virus ◽  
Major Facilitator

Resistance to antifungal drugs, specifically azoles such as fluconazole, in the opportunistic yeast Candida albicans has become an increasing problem in human immunodeficiency virus (HIV)-infected individuals. The molecular mechanisms responsible for this resistance have only recently become apparent and can include alterations in the target enzyme of the azole drugs (lanosterol 14alpha demethylase [14DM]), or in various efflux pumps from both the ABC transporter and major facilitator gene families. To determine which of these possible mechanisms was associated with the development of drug resistance in a particular case, mRNA levels have been studied in a series of 17 clinical isolates taken from a single HIV-infected patient over 2 years, during which time the levels of fluconazole resistance of the strain increased over 200-fold. Using Northern blot analysis of steady-state levels of total RNA from these isolates, we observed increased mRNA levels of ERG16 (the 14DM-encoding gene), CDR1 (an ABC transporter), and MDR1 (a major facilitator) in this series. The timing of the increase in mRNA levels of each of these genes correlated with increases in fluconazole resistance of the isolates. Increased mRNA levels were not observed for three other ABC transporters, two other genes in the ergosterol biosynthetic pathway, or the NADPH-cytochrome P-450 oxidoreductase gene that transfers electrons from NADPH to 14DM. Increases in mRNA levels of ERG16 and CDR1 correlated with increased cross-resistance to ketoconazole and itraconazole but not to amphotericin B. A compilation of the genetic alterations identified in this series suggests that resistance develops gradually and is the sum of several different changes, all of which contribute to the final resistant phenotype.

scholarly journals Molecular typing and in vitro antifungal susceptibility of Cryptococcus spp from patients in Midwest Brazil

2014 ◽  
Vol 8 (08) ◽  
pp. 1037-1043 ◽  
Author(s):  
Olivia Cometti Favalessa ◽  
Daphine Ariadne Jesus De Paula ◽  
Valeria Dutra ◽  
Luciano Nakazato ◽  
Tomoko Tadano ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Fungal Infections ◽  
Antifungal Susceptibility ◽  
Cryptococcus Gattii ◽  
Antifungal Drugs ◽  
Northeastern Brazil ◽  
In Vitro Susceptibility ◽  
Mato Grosso ◽  
Hiv Negative

Introduction: Cryptococcosis is a systemic fungal infection that affects humans and animals, mainly due to Cryptococcus neoformans and Cryptococcus gattii. Following the epidemic of acquired immunodeficiency syndrome (AIDS), fungal infections by C. neoformans have become more common among immunocompromised patients. Cryptococcus gattii has primarily been isolated as a primary pathogen in healthy hosts and occurs endemically in northern and northeastern Brazil. We to perform genotypic characterization and determine the in vitro susceptibility profile to antifungal drugs of the Cryptococcus species complex isolated from HIV-positive and HIV-negative patients attended at university hospitals in Cuiabá, MT, in the Midwestern region of Brazil. Methodology: Micromorphological features, chemotyping with canavanine-glycine-bromothymol blue (CGB) agar and genotyping by URA5-RFLP were used to identify the species. The antifungal drugs tested were amphotericin B, fluconazole, flucytosine, itraconazole and voriconazole. Minimum inhibitory concentrations (MICs) were determined according to the CLSI methodology M27-A3. Results: Analysis of samples yelded C. neoformans AFLP1/VNI (17/27, 63.0%) and C. gattii AFLP6/VGII (10/27, 37.0%). The MICs ranges for the antifungal drugs were: amphotericin B (0.5-1 mg/L), fluconazole (1-16 mg/L), flucytosine (1-16 mg/L), itraconazole (0.25-0.12 mg/L) and voriconazole (0.06-0.5 mg/L). Isolates of C. neoformans AFLP1/VNI were predominant in patients with HIV/AIDS, and C. gattii VGII in HIV-negative patients. The genotypes identified were susceptible to the antifungal drugs tested. Conclusion: It is worth emphasizing that AFLP6/VGII is a predominant genotype affecting HIV-negative individuals in Cuiabá. These findings serve as a guide concerning the molecular epidemiology of C. neoformans and C. gattii in the State of Mato Grosso.

scholarly journals Identification and Expression of Multidrug Transporters Responsible for Fluconazole Resistance in Candida dubliniensis

1998 ◽  
Vol 42 (7) ◽  
pp. 1819-1830 ◽  
Author(s):  
Gary P. Moran ◽  
Dominique Sanglard ◽  
Samantha M. Donnelly ◽  
Diarmuid B. Shanley ◽  
Derek J. Sullivan ◽  
...  
Keyword(s):  
Candida Dubliniensis ◽  
Clinical Isolates ◽  
Metabolic Inhibitors ◽  
Northern Analysis ◽  
Fluconazole Resistance ◽  
Multidrug Transporters ◽  
Oral Candidosis ◽  
Resistant Phenotype ◽  
Fluconazole Resistant

ABSTRACT Candida dubliniensis is a recently describedCandida species associated with oral candidosis in human immunodeficiency virus (HIV)-infected and AIDS patients, from whom fluconazole-resistant clinical isolates have been previously recovered. Furthermore, derivatives exhibiting a stable fluconazole-resistant phenotype have been readily generated in vitro from fluconazole-susceptible isolates following exposure to the drug. In this study, fluconazole-resistant isolates accumulated up to 80% less [3H]fluconazole than susceptible isolates and also exhibited reduced susceptibility to the metabolic inhibitors 4-nitroquinoline-N-oxide and methotrexate. These findings suggested that C. dubliniensis may encode multidrug transporters similar to those encoded by the C. albicans MDR1, CDR1, and CDR2 genes (CaMDR1, CaCDR1, and CaCDR2, respectively). A C. dubliniensis homolog ofCaMDR1, termed CdMDR1, was cloned; its nucleotide sequence was found to be 92% identical to the correspondingCaMDR1 sequence, while the predicted CdMDR1 protein was found to be 96% identical to the corresponding CaMDR1 protein. By PCR,C. dubliniensis was also found to encode homologs ofCDR1 and CDR2, termed CdCDR1 andCdCDR2, respectively. Expression of CdMDR1 in a fluconazole-susceptible Δpdr5 null mutant ofSaccharomyces cerevisiae conferred a fluconazole-resistant phenotype and resulted in a 75% decrease in accumulation of [3H]fluconazole. Northern analysis of fluconazole-susceptible and -resistant isolates of C. dubliniensis revealed that fluconazole resistance was associated with increased expression of CdMDR1 mRNA. In contrast, most studies showed that overexpression of CaCDR1was associated with fluconazole resistance in C. albicans. Increased levels of the CdMdr1p protein were also detected in fluconazole-resistant isolates. Similar results were obtained with fluconazole-resistant derivatives of C. dubliniensis generated in vitro, some of which also exhibited increased levels of CdCDR1 mRNA and CdCdr1p protein. These results demonstrate that C. dubliniensis encodes multidrug transporters which mediate fluconazole resistance in clinical isolates and which can be rapidly mobilized, at least in vitro, on exposure to fluconazole.

scholarly journals Prevalence of Candida dubliniensis Isolates in a Yeast Stock Collection

1998 ◽  
Vol 36 (10) ◽  
pp. 2869-2873 ◽  
Author(s):  
Frank C. Odds ◽  
Luc Van Nuffel ◽  
Géry Dams
Keyword(s):  
Dna Fingerprinting ◽  
Antifungal Agents ◽  
Candida Dubliniensis ◽  
The Novel ◽  
The United Kingdom ◽  
Immunodeficiency Virus ◽  
Chromogenic Agar ◽  
Overt Disease ◽  
Hiv Negative

To establish the historical prevalence of the novel yeast species Candida dubliniensis, a survey of 2,589 yeasts originally identified as Candida albicans and maintained in a stock collection dating back to the early 1970s was undertaken. A total of 590 yeasts, including 93 (18.5%) β-glucosidase-negative isolates among 502 isolates that showed abnormal colony colors on a differential chromogenic agar and 497 other isolates, were subjected to DNA fingerprinting with the moderately repetitive sequence Ca3. On this basis, 53 yeasts were reidentified as C. dubliniensis(including the C. dubliniensis type strain, included as a blind control in the panel of yeasts). The 52 newly found isolates came from 36 different persons, and a further 3 C. dubliniensis isolates were detected by DNA fingerprinting of previously untested isolates from one of these individuals. The prevalence of C. dubliniensis among yeasts in oral and fecal samples was significantly higher than that among yeasts from other anatomical sites and was significantly higher among human immunodeficiency virus (HIV)-infected individuals than among known or presumed HIV-negative individuals. However, a single vaginal isolate and two oral isolates from healthy volunteers confirmed that the species is restricted neither to gastrointestinal sites nor to patients with overt disease. The oldest examples of C. dubliniensis were from oral samples of three patients in the United Kingdom in 1973 and 1975. In comparison with age-matched control isolates of C. albicans, theC. dubliniensis isolates showed slightly higher levels of susceptibility in vitro to amphotericin B and flucytosine and slightly lower levels of susceptibility to three azole antifungal agents.

scholarly journals Effects of the Human Immunodeficiency Virus (HIV) Proteinase Inhibitors Saquinavir and Indinavir on In Vitro Activities of Secreted Aspartyl Proteinases of Candida albicans Isolates from HIV-Infected Patients

1999 ◽  
Vol 43 (8) ◽  
pp. 2038-2042 ◽  
Author(s):  
Hans C. Korting ◽  
Martin Schaller ◽  
Gabriele Eder ◽  
Gerald Hamm ◽  
Ursula Böhmer ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Candida Albicans ◽  
Proteinase Inhibitors ◽  
Oral Candidiasis ◽  
Proteinase Activity ◽  
Dependent Manner ◽  
Immunodeficiency Virus ◽  
Dose Dependent ◽  
Pepstatin A

ABSTRACT The effects of therapeutically relevant concentrations of the human immunodeficiency virus (HIV) proteinase inhibitors saquinavir and indinavir on the in vitro proteinase activity of Candida albicans were investigated with isolates from HIV-infected and uninfected patients with oral candidiasis. After exposure to the HIV proteinase inhibitors, proteinase activity was significantly reduced in a dose-dependent manner. These inhibitory effects, which were similar to that of pepstatin A, and the reduced virulence phenotype in experimental candidiasis after application of saquinavir indicate the usefulness of these HIV proteinase inhibitors as potential anticandidal agents.

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