The hydroxypyridone ciclopirox olamine belongs to the antimycotic drugs used for the treatment of superficial mycoses. In contrast to the azoles and other antimycotic drugs, its specific mode of action is only poorly understood. To investigate the mode of action of ciclopirox olamine on fungal viability, pathogenicity, and drug resistance, we examined the expression patterns of 47 Candida albicans genes in cells grown in the presence of a subinhibitory concentration (0.6 g/ml) of ciclopirox olamine by reverse transcription-PCR. In addition, we used suppression-subtractive hybridization to further identify genes that are up-regulated in the presence of ciclopirox olamine. The expression of essential genes such as ACT1 was not significantly modified in cells exposed to ciclopirox olamine. Most putative and known virulence genes such as genes encoding secreted proteinases or lipases had no or only moderately reduced expression levels. In contrast, exposure of cells to ciclopirox olamine led to a distinct up-or down-regulation of genes encoding iron permeases or transporters (FTR1, FTR2, FTH1), a copper permease (CCC2), an iron reductase (CFL1), and a siderophore transporter (SIT1); these effects resembled those found under iron-limited conditions. Addition of FeCl 3 to ciclopirox olamine-treated cells reversed the effect of the drug. Addition of the iron chelator bipyridine to the growth medium induced similar patterns of expression of distinct iron-regulated genes (FTR1, FTR2). While seruminduced yeast-to-hyphal phase transition of C. albicans was not affected in ciclopirox olamine-treated cells in the presence of subinhibitory conditions, a dramatic increase in sensitivity to oxidative stress was noted, which may indicate the reduced activities of iron-containing gene products responsible for detoxification. Although the Candida drug resistance genes CDR1 and CDR2 were up-regulated, no change in resistance or increased tolerance could be observed even after an incubation period of 6 months. This was in contrast to control experiments with fluconazole, in which the MICs for cells incubated with this drug had noticeably increased after 2 months. These data support the view that the antifungal activity of ciclopirox olamine may at least be partially caused by iron limitation. Furthermore, neither the expression of certain multiple-drug resistance genes nor other resistance mechanisms caused C. albicans resistance to this drug even after long-term exposure.The dimorphic opportunistic fungus Candida albicans is a major cause of mucosal and invasive mycoses. Infections caused by C. albicans are frequently treated with fluconazole, other azole antimycotics, or nonazole antimycotics. The modes of action of the majority of these drugs are well known (24). The imidazoles and triazoles like clotrimazole, ketoconazole, itraconazole, miconazole, fluconazole, and a whole range of similar components act by inhibiting C 14 -demethylase, an enzyme which is involved in the conversion of lanosterol to ergosterol in the ergosterol b...

Candida dubliniensis is often associated with C. albicans in cultures. Easy-to-perform selective isolation procedures for these closely related species do not exist. Therefore, we evaluated previously described discriminatory phenotypic markers forC. dubliniensis. A total of 150 oral rinses from human immunodeficiency virus (HIV)-infected patients were cultured on CHROMagar Candida. Dark green colonies described as being indicative ofC. dubliniensis and other green colonies, 170 in total, were isolated. Chlamydospore formation, intracellular β-d-glucosidase activity, ability to grow at 42°C, carbohydrate assimilation pattern obtained by the API ID 32C, and Fourier transform infrared (FT-IR) spectroscopy were used for phenotypic characterization. Sequencing of the 5′ end of the nuclear large-subunit (26S) ribosomal DNA gene was used for definitive species identification for C. dubliniensis. C. dubliniensis was found in 34% of yeast-colonized HIV-infected patients. The color of the colonies on CHROMagar Candida proved to be insufficient for selecting C. dubliniensis, since only 30 of 53 provenC. dubliniensis isolates showed a dark green color in primary cultures. The described typical chlamydospore formation can give only some indication of C. dubliniensis. The assimilation pattern proved to be insufficient to discriminate C. dubliniensis from C. albicans. All C. dubliniensis strains showed no or highly restricted growth at 42°C and a lack of β-d-glucosidase activity. Unfortunately, atypical C. albicans strains can also exhibit these phenotypic traits. FT-IR spectroscopy combined with hierarchical clustering proved to be as reliable as genotyping for discriminating the two species.

Scedosporium prolificans is one of the most life-threatening fungal opportunistic pathogens due to its high resistance to common systemic antifungal agents. While a close relative of Pseudallescheria boydii, S. prolificans has a more limited geographic range being primarily found in Australia, USA and Spain. Infections have also been reported from several other European countries and from Chile. Twenty patients with Scedosporium prolificans infection or colonization from August 1993 to May 2007 were retrospectively reviewed in Germany. They had all been identified at or reported to the Reference Laboratory for Pseudallescheria/Scedosporium spp. in Berlin. Twelve of 13 patients with haematological disorders and/or on immunosuppressive therapy developed a fatal invasive scedosporiosis. Colonization of the respiratory tract was reported for one patient after heart-lung-transplantation, all six patients with cystic fibrosis and one with chronic sinusitis. Molecular studies of the S. prolificans isolates confirmed that parts of the 18S, the Internal Transcribed Spacer (ITS) regions and the D1/D2 domain of the 28S region of rDNA are monomorphic. However, sequencing of parts of the translation elongation factor EF1-alpha (EF-1alpha) and the chitin synthase (CHS-1) genes revealed the presence of three and two distinct genotypes, respectively. Two informative mutations were found in EF-1alpha and a single nucleotide exchange in the CHS-1 gene.

Microbiology laboratories should be aware of these resistant species in patients with CF and consider using a selective medium.

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A multi-tenant database system for Software as a Service (SaaS) should offer schemas that are flexible in that they can be extended for different versions of the application and dynamically modified while the system is on-line. This paper presents an experimental comparison of five techniques for implementing flexible schemas for SaaS. In three of these techniques, the database "owns" the schema in that its structure is explicitly defined in DDL. Included here is the commonly-used mapping where each tenant is given their own private tables, which we take as the baseline, and a mapping that employs Sparse Columns in Microsoft SQL Server. These techniques perform well, however they offer only limited support for schema evolution in the presence of existing data. Moreover they do not scale beyond a certain level. In the other two techniques, the application "owns" the schema in that it is mapped into generic structures in the database. Included here are XML in DB2 and Pivot Tables in HBase. These techniques give the application complete control over schema evolution, however they can produce a significant decrease in performance. We conclude that the ideal database for SaaS has not yet been developed and offer some suggestions as to how it should be designed.

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