Trailing or paradoxical growth of Candida albicans when exposed to caspofungin is not associated with microsatellite genotypes.

Multilocus microsatellite polymorphisms in 27 clinical Candida albicans isolates were found to be clearly unrelated to in vitro paradoxical growth or trailing effect with caspofungin. These findings suggest that such in vitro phenotypes are either gained or lost too rapidly to be predicted by more stable genomic markers.

Contribution of the (1-->3)-beta-D-glucan assay for diagnosis of invasive fungal infections.

Diagnosis of invasive fungal infection (IFI) remains a challenge. A retrospective study was performed on 279 patients at three French university hospitals to evaluate the performance of the (1-->3)-beta-D-glucan assay (BG assay; Fungitell; Associates of Cape Cod, Inc.) for the diagnosis of IFI. The results of one serum per subject were analyzed for 117 patients who had probable or proven IFI according to the European Organization for Research and Treatment of Cancer criteria (70 invasive pulmonary aspergilloses [IPA], 27 fungal bloodstream infections, and 20 Pneumocystis jiroveci pneumonias), 40 blood donors, and 122 patients who were hospitalized in hematology wards or intensive care units and were at risk for IFI but in whom IFI had not been diagnosed. For the overall IFI diagnosis, the BG assay had 77.8% sensitivity and specificities of 92.5 and 70.5% for blood donors and patients at risk, respectively. The assay was positive in 48 patients with IPA (68%), in 23 with bloodstream infections (85.2%), and in all who had P. jiroveci pneumonias (100%), and the false-positive rate varied depending on the controls used. It allowed a higher rate of detection among IPA patients compared to the galactomannan enzyme-linked immunosorbent assay (ELISA) (48 versus 39 patients, respectively) and among candidemia patients compared to the mannan ELISA (20 versus 11 patients, respectively). This assay therefore appears to be useful in the diagnosis of IFI, particularly for serum analysis of pneumocystosis pneumonia patients, but further studies are needed to evaluate false-positive rates and its future role in IFI diagnosis.

Colony morphology switching of Candida lusitaniae and acquisition of multidrug resistance during treatment of a renal infection in a newborn: case report and review of the literature.

Candida lusitaniae is an emerging opportunistic pathogen which exhibits an unusual antifungal susceptibility pattern. We describe a case of fatal renal infection due to C. lusitaniae in a very low birth weight neonate who was treated with short courses of fluconazole given alternately with amphotericin B. A colony morphology switching was detected on the standard primary culture medium by changes in colony size. Switching was shown to affect deeply the susceptibility to amphotericin B. Afterwards, the switched phenotype developed a cross resistance to fluconazole and itraconazole. Several issues raised by this case are discussed in the light of an extensive review of the literature. Our observations point out the importance of both the detection of colony morphology switching and the close monitoring of antifungal susceptibility in the management of infections due to C. lusitaniae. A judicious therapeutic strategy should prevent the acquisition of multidrug resistance during antifungal therapy.

Interactions between copy number and expression level of genes involved in fluconazole resistance in Candida glabrata.

OBJECTIVES: This study aimed to elucidate the relative involvement of drug resistance gene copy number and overexpression in fluconazole resistance in clinical C. glabrata isolates using a population-based approach. METHODS: Fluconazole resistance levels were quantified using the minimal inhibitory concentration (MIC) via Etest method. Both gene expression levels and gene copy number of CgCDR1, CgPDH1, CgERG11, and CgSNQ2 were assessed via quantitative real-time PCR. The influence of the main effects and first-level interactions of both the expression level and copy number of these genes on fluconazole resistance levels were analyzed using a multivariate statistical model. RESULTS: Forty-three C. glabrata isolates were collected from 30 patients during in a hospital survey. In the multivariate analysis, C. glabrata fluconazole MICs were independently increased by CgSNQ2 overexpression (p < 10(-4)) and the interaction between CgPDH1 gene copy number and CgPDH1 expression level (p = 0.038). In contrast, both CgPDH1 overexpression (p = 0.049) and the interaction between CgSNQ2 and CgERG11 expression (p = 0.003) led to a significant decrease in fluconazole MICs. CONCLUSION: Fluconazole resistance in C. glabrata involves complex interactions between drug resistance gene expression and/or copy number. The population-based multivariate analysis highlighted the involvement of the CgSNQ2 gene in fluconazole resistance and the complex effect of the other genes such as PDH1 for which overexpression was associated with reduced fluconazole resistance levels, while the interaction between PDH1 overexpression and copy number was associated with increased resistance levels.

Differentiation between atypical isolates of Candida lusitaniae and Candida pulcherrima by determination of mating type.

We report on five clinical isolates routinely identified as Candida lusitaniae that the ID 32C system was unable to discriminate from the closely related species Candida pulcherrima. When additional tests did not allow accurate identification, the less usual mating type test identified all of them as Clavispora lusitaniae. Mating type testing appears to be a valuable tool for assessing the true incidence of this emerging non-albicans Candida species.

Susceptibility of clinical isolates of Candida lusitaniae to five systemic antifungal agents.

OBJECTIVES: The aim of the present study was to expand the MIC database for Candida lusitaniae in order to further determine its antifungal susceptibility pattern. METHODS: The activities of amphotericin B, fluconazole, itraconazole, voriconazole and flucytosine were determined in vitro against 80 clinical isolates of C. lusitaniae. A set of 59 clinical isolates of Candida albicans and of 51 isolates of Candida glabrata was included to compare the susceptibilities to amphotericin B. The MICs were determined by Etest with RPMI 1640 agar, and with both this medium and antibiotic medium 3 (AM3) agar for testing of amphotericin B. RESULTS: All isolates were highly susceptible to fluconazole. The susceptibility to itraconazole was good; only 4% of isolates had dose-dependent susceptibility (MICs 0.25-0.5 mg/L). Voriconazole was very active in vitro (100% of isolates were inhibited at < or =0.094 mg/L). Flucytosine MICs ranged widely (0.004->32 mg/L). The set included 19% of flucytosine-resistant isolates. For amphotericin B, 100% of isolates were inhibited at < or =0.75 mg/L (MIC(50) 0.047 mg/L; MIC(90) 0.19 mg/L) and at < or =4 mg/L (MIC(50) 0.25 mg/L; MIC(90) 0.75 mg/L) on RPMI and on AM3, respectively. A single isolate was categorized as resistant to amphotericin B (MIC 0.75 and 4 mg/L on RPMI and on AM3, respectively). Amphotericin B thus appeared very active in vitro against C. lusitaniae. Whatever the test medium, the level of susceptibility of C. lusitaniae to amphotericin B did not differ much from those of C. albicans and C. glabrata. CONCLUSION: C. lusitaniae appears to be susceptible to amphotericin B, azole antifungal agents, and, to a lesser extent, flucytosine.