Invasive candidiasis: an overview from Taiwan

Ascomycetes yeasts: The hidden part of human microbiome

The fungal component of the microbiota, the mycobiota, has been neglected for a long time due to its poor richness compared to bacteria. Limitations in fungal detection and taxonomic identification arise from using metagenomic approaches, often borrowed from bacteriome analyses. However, the relatively recent discoveries of the ability of fungi to modulate the host immune response and their involvement in human diseases have made mycobiota a fundamental component of the microbial communities inhabiting the human host, deserving some consideration in host-microbe interaction studies and in metagenomics. Here, we reviewed recent data on the identification of yeasts of the Ascomycota phylum across human body districts, focusing on the most representative genera, that is, Saccharomyces and Candida. Then, we explored the key factors involved in shaping the human mycobiota across the lifespan, ranging from host genetics to environment, diet, and lifestyle habits. Finally, we discussed the strengths and weaknesses of culture-dependent and independent methods for mycobiota characterization. Overall, there is still room for some improvements, especially regarding fungal-specific methodological approaches and bioinformatics challenges, which are still critical steps in mycobiota analysis, and to advance our knowledge on the role of the gut mycobiota in human health and disease. This article is categorized under: Immune System Diseases > Genetics/Genomics/Epigenetics Immune System Diseases > Environmental Factors Infectious Diseases > Environmental Factors.

Biochanin A Inhibits the Growth and Biofilm of Candida Species

The aim of this study was to investigate the antifungal activity of biochanin A (BCA) against planktonic growth and biofilms of six Candida species, including C. albicans, C. parapsilosis, C. glabrata, C. tropicalis, C. auris, and C. krusei. We applied various assays that determined (a) the antimicrobial effect on growth of Candida species, (b) the effect on formation of hyphae and biofilm, (c) the effect on the expression of genes related to hyphal growth and biofilm formation, (d) the influence on cell wall structure, and (e) the effect on cell membrane integrity and permeability. Moreover, disk diffusion tests were used to investigate the effect of a combination of BCA with fluconazole to assess their possible synergistic effect on drug-resistant C. albicans, C. glabrata, and C. auris. Our results showed that the BCA MIC50 values against Candida species ranged between 125 µg/mL and 500 µg/mL, and the MIC90 values were in a concentration range from 250 µg/mL to 1000 µg/mL. The treatment with BCA inhibited adhesion of cells, cell surface hydrophobicity (CSH), and biofilm formation and reduced hyphal growth in all the analyzed Candida species. Real-time qRT-PCR revealed that BCA down-regulated the expression of biofilm-specific genes in C. albicans. Furthermore, physical destruction of C. albicans cell membranes and cell walls as a result of the treatment with BCA was observed. The combination of BCA and fluconazole did not exert synergistic effects against fluconazole-resistant Candida.

Application of machine learning for mortality prediction in patients with candidemia: Feasibility verification and comparison with clinical severity scores

BACKGROUND

Clinical severity scores, such as acute physiology, age, chronic health evaluation II (APACHE II), sequential organ failure assessment (SOFA), Pitt Bacteremia Score (PBS), and European Confederation of Medical Mycology Quality (EQUAL) score, may not reliably predict candidemia prognosis owing to their prespecified scorings that can limit their adaptability and applicability.

OBJECTIVES

Unlike those fixed and prespecified scorings, we aim to develop and validate a machine learning (ML) approach that is able to learn predictive models adaptively from available patient data to increase adaptability and applicability.

METHODS

Different ML algorithms follow different design philosophies and consequently, they carry different learning biases. We have designed an ensemble meta-learner based on stacked generalisation to integrate multiple learners as a team to work at its best in a synergy to improve predictive performances.

RESULTS

In the multicenter retrospective study, we analysed 512 patients with candidemia from January 2014 to July 2019 and compared a stacked generalisation model (SGM) with APACHE II, SOFA, PBS and EQUAL score to predict the 14-day mortality. The cross-validation results showed that the SGM significantly outperformed APACHE II, SOFA, PBS, and EQUAL score across several metrics, including F1-score (0.68, p < .005), Matthews correlation coefficient (0.54, p < .05 vs. SOFA, p < .005 vs. the others) and the area under the curve (AUC; 0.87, p < .005). In addition, in an independent external test, the model effectively predicted patients' mortality in the external validation cohort, with an AUC of 0.77.

CONCLUSIONS

ML models show potential for improving mortality prediction amongst patients with candidemia compared to clinical severity scores.

Cinnamaldehyde Loaded Poly(lactide-co-glycolide) (PLGA) Microparticles for Antifungal Delivery Application against Resistant Candida albicans and Candida glabrata

Researchers have explored natural products to combat the antibiotic resistance of various microorganisms. Cinnamaldehyde (CIN), a major component of cinnamon essential oil (CC-EO), has been found to effectively inhibit the growth of bacteria, fungi, and mildew, as well as their production of toxins. Therefore, this study aimed to create a delivery system for CIN using PLGA microparticles (CIN-MPs), and to compare the antifungal activity of the carried and free CIN, particularly against antibiotic-resistant strains of Candida spp. The first part of the study focused on synthesizing and characterizing the PLGA MPs, which had no toxic effects in vivo and produced results in line with the existing literature. The subsequent experiments analyzed the antifungal effects of MPs-CIN on Candida albicans and Candida glabrata, both resistant (R) and sensitive (S) strains and compared its efficacy with the conventional addition of free CIN to the culture medium. The results indicated that conveyed CIN increased the antifungal effects of the product, particularly towards C. albicans R. The slow and prolonged release of CIN from the PLGA MPs ensured a constant and uniform concentration of the active principle within the cells.

Anticandidal activity of nanocomposite based on nanochitosan, nanostarch and mycosynthesized copper oxide nanoparticles against multidrug-resistant Candida

Recently, antimicrobial resistance has increased globally particularly Candida infections. Most of antifungal drugs used for treating candidiasis became resistant to most of Candida species. In the current study, a nanocomposite based on mycosynthesized copper oxide nanoparticles (CuONPs), nanostarch, nanochitosan was prepared. Results illustrated that twenty-four Candida isolates were isolated from clinical samples. Furthermore, three Candida strains were selected as the most resistant among others toward commercial antifungal drugs; these selected strains were identified genetically as C. glabrata MTMA 19, C. glabrata MTMA 21 and C. tropicalis MTMA 24. Characterization of the prepared nanocomposite was carried out using physiochemical analysis included Ultraviolet-visible spectroscopy (Uv-Vis), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX) and Transmission Electron Microscopy (TEM). Moreover, the nanocomposite exhibited promising anticandidal activity against C. glabrata MTMA 19, C. glabrata MTMA 21 and C. tropicalis MTMA 24, where the inhibition zones were 15.3, 27 and 28 mm, respectively. Ultrastructure changes observed in nanocomposite-treated C. tropicalis demonstrated disruption of the cell wall which led to cell death. In conclusion, our results confirmed that the novel biosynthesized nanocomposite based on mycosynthesized CuONPs, nanostarch and nanochitosan is a promising anticandidal agent to fight multidrug-resistant Candida.

Role of Candida glabrata as nosocomial pathogen and its susceptibility to Fluconazole, Voriconazole, Caspofungin, Micafungin and Amphotericin B

Candida has different types that could cause bloodstream infections. A total number of 150 samples were collected from candidemia patients and examined. The Candida spp. Species isolated from blood samples were analysed. These were identified by culturing the species using different media, namely the chromogenic agar test. Then, the virulence factors of all samples were tested. The Candida glabrata isolates were tested with six commercial antifungal drugs. C. glabrata 67 (44.6%), C. albicans 34 (22.6%), C. krusei 18 (12%), C. tropicalis 17 (11.3%), and C. parasilosis 14 (9.3%). the production of phospholipase ranged between 0.63-0.99 mm. It was found that 96% of the species showed phospholipase activity in aerobic conditions. The protease activities of Candida spp. Isolates were experimentally tested by area of inhibition around the colonies, where 59.3% had the double (++) protease activity, 31.4% with (+) grade, and 9.3% had (–) grade or clear zone around the colony. The hemolytic capacity ranged from 0.69-0.89 in the optimum aerobic environments. Finally, 38.33% of the isolated Candida spp. were positive and 61.67% negative for biofilm formation. Out of the total positive Candida spp. for biofilm formation, 21.73% were strong biofilm producers, and 78.27% were weak. Minimum fungicidal concentration (MFC) of Fluconazole for C. glabrata isolates was not appropriate (NA) due to the occurrence of low inhibition tested for species. Micafungin exhibited the lowest fungicidal activity against C. glabrata ranging from 0.03 - 0.125, while Fluconazole showed the highest.

Association between CAI microsatellite, multilocus sequence typing, and clinical significance within Candida albicans isolates

Candida albicans bloodstream infection (BSI) is epidemiologically important because of its increasing frequency and serious outcome. Strain typing and delineation of the species are essential for understanding the phylogenetic relationship and clinical significance. Microsatellite CAI genotyping and multilocus sequence typing (MLST) were performed on 285 C. albicans bloodstream isolates from patients in Chang Gung Memorial Hospital at Linkou (CGMHL), Taiwan from 2003 to 2011. Data regarding demographics, comorbidities, risk factors, and clinical outcomes were recorded within adult patients with C. albicans BSI. Both CAI genotyping and MLST yielded comparable discriminatory power for C. albicans characterization. Besides, the distribution of CAI repetition showed a satisfactory phylogenetic association, which could be a good alternative method in the molecular phylogenetics of C. albicans and epidemiological studies. As for the clinical scenario, clade 17 isolates with CAI alleles either possessing 29 or more repetitions were related to higher 14-day and 30-day mortality, and shorter median survival days.

Candida Bloodstream Infection: Changing Pattern of Occurrence and Antifungal Susceptibility over 10 Years in a Tertiary Care Saudi Hospital

Background

Candida has emerged as one of the most important pathogens that cause bloodstream infection (BSI).Understanding the current Candida BSI trends, the dominant species causing disease and the mortality associated with this infection are crucial to optimize therapeutic and prophylaxis measures.

Objectives

To study the epidemiology and to evaluate the risk factors, prognostic factors, and mortality associated with candidemia and to compare these findings with previously published studies from Saudi Arabia.

Design

A retrospective medical record review.

Setting

Tertiary hospital in Riyadh.

Patients and Methods

The analysis included all cases of Candida blood stream infection who are >18 years old over the period from 2013 to 2018. Continuous variables were compared using the parametric T-test while categorical variables were compared using the Chi-squared test.

Main Outcome Measure

Incidence, resistance, and hospital outcomes in Candida blood stream infection.

Sample Size

324 patients.

Results

Three hundred and twenty-four episodes of Candida blood stream infections were identified. Median age of patients was 49.7 SD ± 28.1 years, and 53% of patients were males. More than half of the patients had an underlying disease involving the abdomen or laparotomy, 78% had an indwelling intravenous catheter, and 62% had suffered a bacterial infection within 2 weeks prior to candidemia. Candida albicans represents 33% of all isolates with decreasing trend overtime. There was an increase in the number of nonalbicans Candida overtime with Candida tropicalis in the lead (20%). Use of broad spectrum antibiotics (82%), prior ICU admission (60%) and use of central venous catheters (58%) were the most prevalent predisposing factors of candidemia. Azole resistance was variable overtime. Resistance to caspofungin remained very low (1.9%). Fourteen days crude mortality was 37% for ICU patients and 26.7% in non-ICU patients, while hospital crude mortality was 64.4% and 46.7%, respectively.

Conclusion

There is an increasing trend of nonalbicans Candida blood stream infection. Fluconazole resistance remained low to C. albicans. Most isolates remain susceptible to caspofungin, voriconazole, and amphotericin B. Candida bloodstream infection is associated with high 14-day hospital mortality.

Fungicidal and anti-biofilm activities of trimethylchitosan-stabilized silver nanoparticles against Candida species in zebrafish embryos

Herein, positively surface-charged silver nanoparticles (AgNPs) capped with trimethylchitosan nitrate (TMCN) were synthesized using an environmentally friendly method. Nano-sized TMCN-AgNPs (~80 nm) with high zeta potential (>30 mV) provide sufficient static repulsion to stabilize colloid AgNPs in aqueous solutions without aggregation for >3 months. In in vitro cell cycle assays, TMCN-AgNPs showed low cytotoxicity towards L929 cells. A microdilution inhibition assay demonstrated the antifungal potential of TMCN-AgNPs, with a minimum inhibitory concentration of 0.06 mM against Candida tropicalis ATCC 750, and 0.46 mM against both Candida albicans ATCC 76615 and Candida glabrata ATCC 15545. Moreover, the addition of TMCN-AgNPs at 0.23 mM significantly reduced biofilm formation in 96-well plates with C. albicans and C. tropicalis. Importantly, when zebrafish eggs were infected with Candida cells, 0.23 mM TMCN-AgNPs greatly diminished the amount of biofilm on eggs and rescued the survival of embryos by up to 70%.

FTIR and Raman Spectroscopy-Based Biochemical Profiling Reflects Genomic Diversity of Clinical Candida Isolates That May Be Useful for Diagnosis and Targeted Therapy of Candidiasis

Despite the fact that Candida albicans is documented to be the main cause of human candidiasis, non-C. albicans Candida (NCAC) species, such as Candida glabrata and Candida tropicalis, are also suggested to be implicated in the etiopathogenesis of opportunistic fungal infections. As biology, epidemiology, pathogenicity, and antifungal resistance of NCAC species may be affected as a result of genomic diversity and plasticity, rapid and unambiguous identification of Candida species in clinical samples is essential for proper diagnosis and therapy. In the present study, 25 clinical isolates of C. albicans, C. glabrata, and C. tropicalis species were characterized in terms of their karyotype patterns, DNA content, and biochemical features. Fourier transform infrared (FTIR) spectra- and Raman spectra-based molecular fingerprints corresponded to the diversity of chromosomal traits and DNA levels that provided correct species identification. Moreover, Raman spectroscopy was documented to be useful for the evaluation of ergosterol content that may be associated with azole resistance. Taken together, we found that vibrational spectroscopy-based biochemical profiling reflects the variability of chromosome patterns and DNA content of clinical Candida species isolates and may facilitate the diagnosis and targeted therapy of candidiasis.

DST659 genotype of Candida albicans showing positive association between biofilm formation and dominance in Taiwan

Based on multiple locus sequence typing, we previously found that DST659 and DST693 were dominant genotypes of Candida albicans among the bloodstream isolates at Chang-Gung Memorial Hospital at Linkou. Biofilm-forming activity, which is critical for C. albicans virulence, probably contributed to the dominance of antifungal sensitive isolates in hospital. Both in vitro membrane weighting and in vivo zebrafish egg infection assays were used to evaluate the biofilm-forming activity of DST659 and DST693 genotypes. Medical records of the patients infected by these two genotypes were retrospectively reviewed. High biofilm-forming activity of DST659 isolates was demonstrated in vitro and further proved with the zebrafish egg infection model, which showed a positive correlation between the biofilm-forming extent on chorion and the in vitro biofilm activity. Moreover, significantly less embryos survived when infected with DST659 isolates than those with DST693 (1.25% vs. 11.43%), and the high-biofilm subset of DST659 showed a greater reduction in survival of embryos at 48 h post-infection than the low-biofilm subset (0 vs. 1.92%). Patients infected with DST659 seemed to survive slightly worse than those infected with DST693, although the difference was insignificant. It is noteworthy that DST659-infected patients were associated with a higher incidence in renal insufficiency as compared to those with DST693, the low biofilm genotype. We suggest that a strong biofilm activity of DST659 contributed to a high mortality rate in zebrafish hosts and poor renal function in patients, as well as gaining the dominance in the northern Taiwan.

An Update on the Roles of Non-albicans Candida Species in Vulvovaginitis

Candida species are one of the commonest causes of vaginitis in healthy women of reproductive age. Vulvovaginal candidiasis (VVC) is characterized by vulvovaginal itching, redness and discharge. Candida albicans, which is a common genito-urinary tract commensal, has been the prominent species and remains the most common fungal agent isolated from clinical samples of patients diagnosed with VVC. In recent times, however, there has been a notable shift in the etiology of candidiasis with non-albicans Candida (NAC) species gaining prominence. The NAC species now account for approximately 10% to as high as 45% of VVC cases in some studies. This is associated with treatment challenges and a slightly different clinical picture. NAC species vaginitis is milder in presentation, often occur in patients with underlying chronic medical conditions and symptoms tend to be more recurrent or chronic compared with C. albicans vaginitis. C. glabrata is the most common cause of NAC-VVC. C. tropicalis, C. krusei, C. parapsilosis, and C. guilliermondii are the other commonly implicated species. Treatment failure is common in NAC-VVC, since some of these species are intrinsically resistant or show low susceptibilities to commonly used antifungal agents. This article reviews the etiology, pathogenesis, clinical features, diagnosis, and management of NAC vulvovaginitis.

Identification of medically important Candida species by polymerase chain reaction-restriction fragment length polymorphism analysis of the rDNA ITS1 and ITS2 regions

AIM

We aimed to identify the distribution of species in candidal strains isolated from clinical samples and restriction fragment length polymorphism (RFLP) method based on Msp I and Bln I restrictive enzyme cuts of polymerase chain reaction (PCR) products after the amplification of ITS1 and ITS2 regions of rDNA genotypically.

MATERIALS AND METHODS

One hundred and fifty candidal strains isolated from various clinical samples were studies/ included. Phenotypic species assessment was performed using automated VITEK-2 system and kit used with the biochemical tests. Common genomic region amplification peculiar to candidal strains was carried out using ITS1 and ITS2 primer pairs. After the amplification, PCR products were cut with Msp I and Bln I restriction enzymes for species identification.

RESULTS

The majority of Candida isolates were isolated from urine (78.6%) while other isolates were composed of strains isolated from swab, wound, blood and other samples by 11.3%, 3.3%, 2% and 4.7%, respectively. The result of RFLP analysis carried out with Msp I and Bln I restriction enzymes showed that candidal strains were Candida albicans by 45.3%, Candida glabrata by 19.3%, Candida tropicalis by 14.6%, Candida parapsilosis by 5.3%, Candida krusei by 5.3%, Candida lusitaniae by 0.6% and other candidal strains by 9.3%.

CONCLUSION

When the ability to identify Candida to species level of phenotypic and PCR-RFLP methods was assessed, a great difference was found between these two methods. It may be argued that Msp I and Bln I restriction enzyme fragments can be used in the identification of medically important Candida species. Further studies are needed to develop this kind of restriction profile to be used in the identification of candidal strains.

Risk factors and outcomes of candidemia caused by Candida parapsilosis complex in a medical center in northern Taiwan

To investigate the risk factors and outcomes associated with Candida parapsilosis candidemia, a retrospective study was conducted at a tertiary medical center in northern Taiwan. Patients with C. parapsilosis candidemia and corresponding controls with C. albicans candidemia were chosen and their demographics, comorbidities, risk factors, and clinical outcomes were reviewed. Antifungal susceptibility tests were performed using the Sensititre YeastOne colorimetric system. Matrix-assisted laser desorption ionization-time of flight mass spectrometry was used to classify the genomic species. Of the 270 candidemias found in 253 patients, C. albicans was the most common Candida species isolated (43.0%), followed by C. parapsilosis (22.6%), C. tropicalis (17.4%), and C. glabrata (10.0%). The 30-day mortality of C. parapsilosis candidemia was significantly lower than that of C. albicans candidemia (21.7% vs. 53.9%, P<0.001). C. parapsilosis was positively associated with antifungal agent exposure [OR 7.261 (95% CI, 1.603-32.879), P=0.010], but negatively associated with Candida colonization [OR 0.303 (95% CI, 0.123-0.745), P=0.009], and immunosuppressant use [OR 0.264 (95% CI, 0.099-0.705), P=0.008]. In-hospital mortality was associated with the Sequential Organ Failure Assessment Score [OR 1.255 (95% CI, 1.002-1.573), P=0.048]. The clinical outcomes did not differ across genomic species and in the minimum inhibitory concentrations of fluconazole.

2016 guidelines for the use of antifungal agents in patients with invasive fungal diseases in Taiwan

The Infectious Diseases Society of Taiwan, Medical Foundation in Memory of Dr. Deh-Lin Cheng, Foundation of Professor Wei-Chuan Hsieh for Infectious Diseases Research and Education, and CY Lee's Research Foundation for Pediatric Infectious Diseases and Vaccines have updated the guidelines for the use of antifungal agents in adult patients with invasive fungal diseases in Taiwan. This guideline replaces the 2009 version. Recommendations are provided for Candida, Cryptococcus, Aspergillus and Mucormycetes. The focus is based on up-to-date evidence on indications for treatment or prophylaxis of the most common clinical problems. To support the recommendations in this guideline, the committee considered the rationale, purpose, local epidemiology, and key clinical features of invasive fungal diseases to select the primary and alternative antifungal agents. This is the first guideline that explicitly describes the quality and strength of the evidence to support these recommendations. The strengths of the recommendations are the quality of the evidence, the balance between benefits and harms, resource and cost. The guidelines are not intended nor recommended as a substitute for bedside judgment in the management of individual patients, the advice of qualified health care professionals, and more recent evidence concerning therapeutic efficacy and emergence of resistance. Practical considerations for individualized selection of antifungal agents include patient factors, pathogen, site of infection and drug-related factors, such as drug-drug interaction, drug-food intervention, cost and convenience. The guidelines are published in the Journal of Microbiology, Immunology and Infection and are also available on the Society website.

Antiproliferation of Berberine in Combination with Fluconazole from the Perspectives of Reactive Oxygen Species, Ergosterol and Drug Efflux in a Fluconazole-Resistant Candida tropicalis Isolate

Candida tropicalis has emerged as an important pathogenic fungus in nosocomial infections due to its recalcitrant resistance to conventional antifungal agents, especially to fluconazole (FLC). Berberine (BBR) is a bioactive herbal-originated alkaloids and has been reported to possess antifungal functions against C. albicans. In this paper, we tried to figure out the antifungal mechanisms of BBR and/or FLC in a clinical C. tropicalis isolate 2006. In the microdilution test, the minimum inhibitory concentration (MIC) of BBR was found 16 μg/mL with fractional inhibitory concentration index (FICI) 0.13 in C. tropicalis 2006. The synergism of BBR and FLC was also confirmed microscopically. After the treatments of BBR and/or FLC, the studies revealed that (i) FLC facilitated BBR to increase reactive oxygen species (ROS), (ii) FLC enhanced the intranuclear accumulation of BBR, (iii) BBR decreased the extracellular rhodamine 123 (Rh123) via inhibiting efflux transporters, (iv) FLC assisted BBR to reduce ergosterol content, and (v) BBR in combined with FLC largely downregulated the expressions of Candida drug resistance 1 (CDR1) and CDR2 but impact slightly multidrug resistance 1 (MDR1), and upregulate the expression of ergosterol 11 (ERG11). These results suggested that BBR could become a potent antifungal drug to strengthen FLC efficacy in FLC-resistant C. tropicalis via ROS increase, intracellular BBR accumulation, ergosterol decrease and efflux inhibition.

Propolis: a potential natural product to fight Candida species infections

AIM

To evaluate the effect of propolis against Candida species planktonic cells and its counterpart's biofilms.

MATERIALS & METHODS

The MIC values, time-kill curves and filamentation form inhibition were determined in Candida planktonic cells. The effect of propolis on Candida biofilms was assessed through quantification of CFUs.

RESULTS

MIC values, ranging from 220 to 880 µg/ml, demonstrated higher efficiency on C. albicans and C. parapsilosis than on C. tropicalis cells. In addition, propolis was able to prevent Candida species biofilm's formation and eradicate their mature biofilms, coupled with a significant reduction on C. tropicalis and C. albicans filamentation.

CONCLUSION

Propolis is an inhibitor of Candida virulence factors and represents an innovative alternative to fight candidiasis.

Catheter-Related Bloodstream Infection Due to Lodderomyces elongisporus

Lodderomyces elongisporus infrequently causes bloodstream infections and has been isolated from Asia and Mexico. We encountered a catheter-related bloodstream infection, which involved some risk factors, due to L. elongisporus masquerading as Candida parapsilosis. A 39-year-old man who received a total arch and thoracoabdominal aortic replacement was admitted with a diagnosis of aorto-esophageal fistula. After thoracic drainage for the aorto-esophageal fistula, a catheter-related bloodstream infection was diagnosed. Micafungin (100 mg/day) was successfully administered to treat the catheter-related bloodstream infection for 42 days in total. The bloodstream and catheter tip yeast was grown on Candida agar medium and produced dark green colonies indicating Candida albicans. We performed sequencing analysis using a GenBank BLAST search. The sequence of the internal transcribed spacer region was 99.9% identical with that of the type strain L. elongisporus. This yeast organism has frequently been technically mistaken for non-albicans Candida spp. Furthermore, the prognosis and risk factors of L. elongisporus infection remain unclear owing to the scarcity of reported cases. Catheter-related bloodstream infection caused by this organism has not been described to date.

Synthesis andIn VitroEvaluation of New Thiosemicarbazone Derivatives as Potential Antimicrobial Agents

In an effort to develop potent antimicrobial agents, new thiosemicarbazone derivatives were synthesizedviathe reaction of 4-[4-(trifluoromethyl)phenyl]thiosemicarbazide with aromatic aldehydes. The compounds were evaluated for their inhibitory effects on pathogenic bacteria and yeasts using the CLSI broth microdilution method. Microplate Alamar Blue Assay was also carried out to determine the antimycobacterial activities of the compounds againstMycobacterium tuberculosisH37Rv. Among these derivatives, compounds5and11were more effective againstEnterococcus faecalis(ATCC 29212) than chloramphenicol, whereas compounds1,2, and12and chloramphenicol showed the same level of antibacterial activity againstE. faecalis. Moreover, compound2and chloramphenicol exhibited the same level of antibacterial activity againstStaphylococcus aureus. On the other hand, the most potent anticandidal derivatives were found as compounds2and5. These derivatives and ketoconazole exhibited the same level of antifungal activity againstCandida glabrata. According to the Microplate Alamar Blue Assay, the tested compounds showed weak to moderate antitubercular activity.

Prospective evaluation of the chromogenic medium CandiSelect 4 for differentiation and presumptive identification of non-Candida albicans Candida species

Rapid identification of pathogenic yeasts is a crucial step in timely and appropriate antifungal therapy. For diagnostics in the clinical laboratory, simplified alternatives to barcoding are needed. CandiSelect 4 (CS4) medium, a chromogenic medium for isolation of clinical yeasts, allows routine recognition of Candida albicans and presumptive identification of Candida tropicalis, Candida glabrata, and Candida krusei. We evaluated an extension of this method with 46 non-Candida albicans Candida (NCAC) and 7 Malassezia species. The medium supported growth of all species tested and a wide diversity of cultural types were observed. Colony colours were in violet, turquoise (including green and blue), or white tinges. Eight NCAC species produced violet pigmentation similar to that of C. albicans. Most NCAC species, including C. glabrata and C. tropicalis were distributed in the turquoise group. Malassezia species were invariably blue.

Molecular epidemiology of invasive Candida albicans at a tertiary hospital in northern Taiwan from 2003 to 2011

Candida albicans is a common cause of bloodstream fungal infections in hospitalized patients. To investigate its epidemiology, multilocus sequence typing (MLST) was performed on 285 C. albicans bloodstream isolates from patients in Chang Gung Memorial Hospital at Linkou (CGMHL), Taiwan from 2003 to 2011. Among these isolates, the three major diploid sequence types (DSTs) were 693, 659, and 443 with 19, 16, and 13 isolates, respectively. The 179 DSTs were classified into 16 clades by unweighted pair-group method using arithmetic averages (UPGMA). The major ones were clades 1, 4, 3, and 17 (54, 49, 31, and 31 isolates, respectively). Further analyses with eBURST clustered the 285 isolates into 28 clonal complexes (CC). The most common complexes were CC8, CC20, and CC9. DST 693 that had the highest number of isolates was determined to be the cluster founder of CC20, which belonged to clade 3. So far, 33 isolates worldwide including 29 from Taiwan and 4 from Korea, are CC20, suggesting that CC20 is an Asian cluster. Two fluconazole-resistant isolates belonging to CC12 and CC19 were detected. All other CGMHL isolates were susceptible to 5-flucytosine, amphotericin B, anidulfungin, caspofungin, fluconazole, itraconazole, micafungin, posaconazole, and voriconazole. However, CC20 isolates exhibited significantly lower susceptibility to fluconazole. In conclusion, the 285 CGMHL C. albicans isolates displayed geographically clustering with Asian isolates, and most of them are susceptible to common antifungal drugs. Isolates of DST 693, a Taiwanese major genotype belonging to MLST clade 3, were more resistant to fluconazole than other isolates.

Systemic Candida parapsilosis Infection Model in Immunosuppressed ICR Mice and Assessing the Antifungal Efficiency of Fluconazole

This study was to establish a systemic C. parapsilosis infection model in immunosuppressed ICR mice induced by cyclophosphamide and evaluate the antifungal efficiency of fluconazole. Three experiments were set to confirm the optimal infectious dose of C. parapsilosis, outcomes of infectious model, and antifungal efficiency of fluconazole in vivo, respectively. In the first experiment, comparisons of survival proportions between different infectious doses treated groups showed that the optimal inoculum for C. parapsilosis was 0.9 × 10⁵ CFU per mouse. The following experiment was set to observe the outcomes of infection at a dose of 0.9 × 10⁵ CFU C. parapsilosis. Postmortem and histopathological examinations presented fugal-specific lesions in multiorgans, especially in kidneys, characterized by inflammation, numerous microabscesses, and fungal infiltration. The CFU counts were consistent with the histopathological changes in tissues. Th1/Th2 cytokine imbalance was observed with increases of proinflammatory cytokines and no responses of anti-inflammatory cytokines in sera and kidneys. In the last experiment, model based evaluation of fluconazole indicated that there were ideal antifungal activities for fluconazole at dosages of 10–50 mg/kg/d. Data demonstrates that the research team has established a systemic C. parapsilosis infection model in immunosuppressed ICR mice, affording opportunities for increasing our understanding of fungal pathogenesis and treatment.

High Incidences of Invasive Fungal Infections in Acute Myeloid Leukemia Patients Receiving Induction Chemotherapy without Systemic Antifungal Prophylaxis: A Prospective Observational Study in Taiwan

Invasive fungal infections (IFIs) is an important complication for acute myeloid leukemia (AML) patients receiving induction chemotherapy. However, the epidemiological information is not clear in Southeastern Asia, an area of potential high incidences of IFIs. To clarify it, we enrolled 298 non-M3 adult AML patients receiving induction chemotherapy without systemic anti-fungal prophylaxis from Jan 2004 to Dec 2009, when we applied a prospective diagnostic and treatment algorithm for IFIs. Their demographic parameters, IFI characters, and treatment outcome were collected for analysis. The median age of these patients was 51 years. Standard induction chemotherapy was used for 246 (82.6%) patients, and 66.8% of patients achieved complete remission (CR) or partial remission. The incidence of all-category IFIs was 34.6% (5.7% proven IFIs, 5.0% probable IFIs and 23.8% possible IFIs). Candida tropicalis was the leading pathogen among yeast, and lower respiratory tract was the most common site for IFIs (75.4%, 80/106). Standard induction chemotherapy and failure to CR were identified as risk factors for IFIs. The presence of IFI in induction independently predicted worse survival (hazard ratio 1.536 (1.100–2.141), p value = 0.012). Even in those who survived from the initial IFI insults after 3 months, the presence of IFIs in induction still predicted a poor long-term survival. This study confirms high incidences of IFIs in Southeastern Asia, and illustrates potential risk factors; poor short-term and long-term outcomes are also demonstrated. This epidemiological information will provide useful perspectives for anti-fungal prophylaxis and treatment for AML patients during induction, so that best chances of cure and survival can be provided.

Clinical isolates of Candida albicans, Candida tropicalis, and Candida krusei have different susceptibilities to Co(II) and Cu(II) complexes of 1,10-phenanthroline

The minimal inhibitory concentrations (MICs) of copper and cobalt based dimeric pyrophosphate complexes with capping 1,10-phenanthroline groups on clinical isolates of C. albicans (28 isolates), C. krusei (20 isolates) and C. tropicalis (20 isolates) are reported. C. albicans was inhibited by the cobalt complex better than by the copper complex, while C. krusei demonstrated the opposite results. C. tropicalis showed similar sensitivities to both metals in terms of calculated MIC50 values but was more sensitive to cobalt when MIC90 values were noted. Knockout strains of C. albicans that had the copper efflux protein P-type ATPase (CRP1), the copper binding metallothionein CUP1 or both CRP1/CUP1 removed clearly demonstrate that the origins of copper resistant in C. albicans lies primarily in the P-type ATPase, with the MT playing an important secondary role in the absence of the efflux protein. This study suggests that certain strains of Candida have evolved to protect against particular metal ions and that in the case of C. albicans, a primary invasive fungal species, cobalt may be a good starting-point for new therapeutic development.

Clinical manifestations and prognostic factors of central line-associated candidemia

From 2009-2012, a total of 281 episodes of central line-associated candidemia were identified, and the overall incidence was 2.05 episodes per 1,000 hospital admissions. More than half of the patients were classified as older adults, with an age ≥65 years. Cancer was the most common underlying disease (n = 231, 82.2%). Twenty patients had polycandidal candidemia, and 94 had concomitant bacteremia. The overall in-hospital mortality rate was 50.9%, and a multivariable analysis showed that this rate was only significantly associated with a Charlson comorbidity index score >5, jaundice, no antifungal agent use, and use of mechanical ventilators.

Resistance reversal induced by a combination of fluconazole and tacrolimus (FK506) in Candida glabrata

There is an increasing concern about Candida glabrata due to its high isolation frequency in candidiasis recently and notorious drug resistance to fluconazole. Drug combination is one effective approach to counteract drug resistance. This study aimed to test whether a combination of fluconazole and tacrolimus (FK506) had a synergistic effect on C. glabrata, and to seek the potential mechanisms underlying the synergistic effects. In vitro effects of fluconazole and FK506 against C. glabrata with different susceptibilities were investigated by a chequerboard method and a time-kill curve method. The mechanistic studies against the resistant C. glabrata were performed from two aspects: quantification of expression levels of fluconazole resistance genes (ERG11, CDR1, PDH1 and SNQ2) by real-time quantitative PCR and functional assays of drug efflux pumps. The addition of FK506 resulted in a decrease in the MIC of fluconazole from 32 to 8 µg ml(-1) against the dose-dependent susceptible C. glabrata, and from 256 to 16 µg ml(-1) against the resistant C. glabrata, respectively. The synergy was further confirmed by the time-kill assay. The expression levels of the ERG11 and SNQ2 genes were significantly downregulated after exposure to the drug combination, whereas that of the CDR1 gene was significantly upregulated, and no significant change in expression of PDH1 gene was observed. Flow cytometric assays showed that FK506 reduced the efflux of fluconazole. Tacrolimus enhanced the susceptibility of fluconazole against resistant C. glabrata by reducing the expression levels of the ERG11 and SNQ2 genes and inhibiting fluconazole efflux.

Antimicrobial susceptibility and clinical outcomes of Candida parapsilosis bloodstream infections in a tertiary teaching hospital in Northern Taiwan

BACKGROUND

Candida parapsilosis is an emerging non-albicans Candida that is associated with central line-associated infection. C. parapsilosis has higher minimal inhibitory concentration to echinocandin than Candida albicans, and the effects of echinocandin on C. parapsilosis are ambiguous. Therefore, in this study, we aimed to investigate the susceptibility and the correlation between incidence and drug consumption.

METHODS

This retrospective study was conducted in a tertiary teaching hospital in northern Taiwan between 2008 and 2012. The Candida species distribution, the correlation between the use of antifungal agents and the incidence of C. parapsilosis bloodstream infection, demographic information, clinical characteristics, mortality rate, and in vitro susceptibility of C. parapsilosis were analyzed.

RESULTS

A total of 77 episodes from 77 patients were included for analysis. The overall 90-day mortality rate was 41.6%. The incidence of C. parapsilosis bloodstream infection showed a moderate positive correlation with the increased defined daily dose of echinocandin. The risk factors associated with mortality included malignancy or a metastatic tumor. Multivariate logistical regression analysis showed that patients with malignancy had higher odds ratios in terms of mortality. The rate of C. parapsilosis resistance to fluconazole was 3%, whereas the susceptibility rate was 95.5%.

CONCLUSION

Underlying comorbidity and malignancy were factors leading to death in patients with C. parapsilosis bloodstream infection. Catheter removal did not influence the mortality rate. The survival rate of patients receiving echinocandin was lower than the group receiving fluconazole. Fluconazole remains the drug of choice to treat C. parapsilosis bloodstream infections.

Epidemiology and prognostic factors of candidemia in elderly patients

AIM

The present retrospective study was carried out to investigate the epidemiological characteristics and the prognostic factors of candidemia among elderly patients.

METHODS

From 2009 to 2012, elderly patients with candidemia were identified at the Chi Mei medical center, a 900-bed regional hospital in southern Taiwan, and their medical records retrospectively reviewed.

RESULTS

During the 4-year period, a total of 175 episodes of candidemia among elderly patients were identified. The patients ranged in age from 65 to 98 years (mean 76.4 years) and the mean (±standard deviation) Charlson Comorbidity Index score was 7.6 (±2.7). Cancer was the most common underlying disease (n = 127, 72.6%), followed by diabetes mellitus (n = 69, 39.4%). Candida albicans (n = 96, 54.9%) was the most common pathogen, followed by C. tropicalis (n = 39, 22.3%), C. parapsilosis (n = 24, 13.7%), C. glabrata (n = 22, 12.6%), C. guilliermondii (n = 2, 1.1%) and Candida species (n = 3, 1.7%). The ratio of C. albicans causing candidemia was significantly higher in young-old than old-old patients (64.1% vs 47.4%, P = 0.027). The overall in-hospital mortality was 50.3%. Multivariate analysis showed that the in-hospital mortality was only significantly associated with jaundice (P = 0.004), no use of antifungal agent (P = 0.021) and intensive care unit admission (P < 0.001).

CONCLUSIONS

Candidemia can develop in elderly patients, especially patients with cancer or other risk factors. C. albicans is the most common Candida species causing candidemia among elderly patients, followed by C. tropicalis. The mortality of candidemia among elderly patients remains high.

Short-term exposure to fluconazole induces chromosome loss in Candida albicans: an approach to produce haploid cells

Candida albicans is considered to be an obligate diploid fungus. Here, we describe an approach to isolate aneuploids or haploids induced by the short-term (12-16 h) exposure of diploid reference strains SC5314 and CAI4 to the most commonly used antifungal drug, fluconazole, followed by repeated single-cell separation among small morphologically distinct colonies in the inhibition zone. The isolated strains had altered cell morphology and LOH events in the MTL and other marker alleles of the analyzed loci at 8 chromosomes of C. albicans with decreased DNA content. The present study employed next-generation sequencing (NGS) combined flow cytometry analysis of the DNA content to analyze the haploid, autodiploid, and aneuploid strains that arose from the fluconazole treatment instead of using the conventional single nucleotide polymorphism/comparative genome hybridization (SNP/CGH) method. A multiple-alignment tool was also developed based on sequenced data from NGS to establish haplotype mapping for each chromosome of the selected strains. These findings revealed that C. albicans experiences 'concerted chromosome loss' to form strains with homozygous alleles and that it even has a haploid status after short-term exposure to fluconazole. Additionally, we developed a new platform to analyze chromosome copy number using NGS.

Epidemiology and prognostic factors of candidemia in cancer patients

Aim

The study of candidemia in cancer patients has been limited. This retrospective study aims to investigate the epidemiologic characteristics and prognostic factors of candidemia among cancer patients.

Materials and Methods

From 2009 to 2012, cancer patients with candidemia were identified at a hospital in Taiwan. The medical records of all patients with bloodstream infections due to Candida species were retrospectively reviewed.

Results

During the four-year period, a total of 242 episodes of candidemia were identified among cancer patients. Half of these patients were classified as elderly (≥65 years old), and more than 95% of the candidemia episodes were classified as healthcare-associated infections. Among the 242 cancer patients with candidemia, head and neck cancer was the most common, followed by gastrointestinal tract and lung cancer. Additionally, most of the patients had variable underlying conditions, such as the presence of CVC (99%) or prior exposure to broad-spectrum antibiotics (93%) and were receiving an immunosuppressant (86%). Overall, C. albicans (n = 132, 54.5%) was the most common pathogen, followed by C. tropicalis (n = 52, 21.5%), C. parapsilosis (n = 38, 15.7%), and C. glabrata (n = 29, 12.0%). Seventeen patients had polycandidal candidemia, and 77 patients had concomitant bacteremia. Approximately one-third of the patients required admission to the intensive care unit (ICU) or mechanical ventilation, and the overall in-hospital mortality was 50.8%. Multivariable analysis showed that the in-hospital mortality was significantly associated with only the non-use of antifungal agents and acute respiratory failure (P<.001).

Conclusions

Candidemia can develop in patients with both solid cancer and hematological malignancy, especially for patients with underlying conditions. Overall, the associated morbidity and mortality due to Candidemia remain high. It was also determined that the non-use of antifungal agents and acute respiratory failure conditions were associated with in-hospital mortality.

Candida empyema thoracis at a hospital in Taiwan

BACKGROUND

We conducted a study of the clinical manifestations and outcomes of empyema thoracis caused by Candida spp. in hospitalized patients.

METHODS

We identified patients who from January 2010 to June 2012 had signs of inflammation, such as fever and leukocytosis, and concomitant positive cultures of Candida spp. from specimens of pleural fluid. We reviewed retrospectively the medical records of all such patients.

RESULTS

Eight of the patients in whom we identified fever and leukocytosis with concomitant positive pleural fluid cultures of Candida spp. were found to have Candida empyema thoracis. Candida albicans was the most common species causing empyema (n=4), followed by C. glabrata (n=3) and C. tropicalis (n=1). Among the eight patients with Candida empyema thoracis, malignant disease was the most common underlying disease. Seven of the eight patients' episodes of Candida empyema thoracis (87.5%) were classified as health care-associated infections. One patient had a mixed infection with Candida spp. and Pseudomonas aeruginosa. None of the patients had concomitant candidemia. Fluconazole was the antifungal agent used most commonly in treating the patients, and all of the patients had drainage of pleural effusions, including tube thoracostomy in five patients and drainage through a pigtail catheter in three patients. One patient underwent video-assisted thoracic surgery for the management of empyema thoracis, and the patients' overall in-hospital mortality was 62.5%.

CONCLUSION

Although Candida empyema thoracis is encountered rarely, it can develop in immunocompromised patients and can be associated with a high mortality rate.

Antifungal susceptibilities of Candida isolates causing bloodstream infections at a medical center in Taiwan, 2009-2010

We used the Sensititre YeastOne (SYO) method (Trek Diagnostic Systems) to determine the MICs of nine antifungal agents against 474 nonduplicate blood Candida isolates. The MIC results were interpreted according to updated clinical breakpoints (CBPs) recommended by the Clinical and Laboratory Standards Institute (CLSI; document M27-S4) or epidemiology cutoff values (ECVs). The rates of fluconazole susceptibility were 99.2% (234/236) in Candida albicans, 86.7% (85/98) in C. tropicalis, and 97.7% (42/43) in C. parapsilosis. Among the 77 isolates of C. glabrata, 90.9% showed dose-dependent susceptibility (S-DD) to fluconazole. Nearly all isolates of C. albicans, C. parapsilosis, and C. krusei were susceptible to voriconazole; however, rates of voriconazole susceptibility were 78.6% in C. tropicalis. Few isolates of C. albicans (n = 5; 2.1%) and C. glabrata (n = 3; 3.9%), no isolates of C. parapsilosis, C. krusei, and C. guilliermondii, but 62.2% (n = 51) of C. tropicalis isolates were non-wild type for posaconazole susceptibility. For itraconazole susceptibility, 98.3% of C. albicans isolates were wild type, and 3.9% (n = 3) of C. glabrata isolates were non-wild type. Almost all of the isolates tested (>97% for all species) were susceptible to both micafungin and anidulafungin. All isolates tested were found to be wild type for amphotericin B susceptibility, with MICs of <1 μg/ml. Further evaluation is needed to establish CBPs of antifungal agents by the 24-h SYO method for the management of patients with candidemia or other invasive candida infections.

Effects of fluconazole on Candida glabrata biofilms and its relationship with ABC transporter gene expression

Candida glabrata has emerged as the second most prevalent fungal pathogen and its ability to form biofilms has been considered one of the most important virulence factors, since biofilms present a high tolerance to antifungal agents used in fungal infection treatment. The mechanisms of biofilm tolerance to antifungal agents remain poorly understood. Thus, the aim of this study was to evaluate the effects of fluconazole (FLU) on the formation and control of C. glabrata biofilms and its relation with the expression of genes encoding for ABC transporters, CDR1, SNQ2, and PDR1. For that, minimal inhibitory concentration values for seven C. glabrata strains were determined and the effect of FLU against C. glabrata biofilms was evaluated by total biomass quantification and viable cell enumeration. Matrices from biofilms were analyzed in terms of protein, carbohydrate and DNA content. ABC transporter gene expression was analyzed for quantitative real-time PCR. In addition to the high amounts of proteins and carbohydrates detected in the extracellular matrices in the presence of FLU, this work showed that the overexpression of efflux pumps is a possible mechanism of biofilm tolerance to FLU and this phenomenon alters the structure of C. glabrata biofilms by creating cell clusters.

Impact of glucose levels on expression of hypha-associated secreted aspartyl proteinases in Candida albicans

BACKGROUND

Ten secreted aspartyl proteinase (Sap) genes were identified in Candida albicans. The products of SAP genes are considered to be virulent factors of C. albicans that participated in causing mucocutaneous and systemic candidiasis in humans. Depending on environmental conditions, C. albicans may stay in yeast-form or convert into invasive hypha-form, and these issues may affect the expression of SAP genes. In this study we explored the component(s) of culture media that may affect the expression of hypha-associated SAP genes.

RESULTS

We demonstrate that glucose levels modulate both the hyphae development and the expression strength of hypha-associated SAP genes (SAP4-6). In contrast to high glucose concentration (2%), lower glucose level (0.1%) is more potent to promote hyphae development and to promptly elicit the expression of hypha-associated Sap proteins during yeast-to-hypha transition of C. albicans. Both Cph1-mediated MAP kinase cascade and Efg1-mediated cAMP/PKA pathway, although the latter seemed dominant, participate in convey the glucose signaling to regulate the expression of hypha-associated SAP genes and this glucose level effect may perform at very early stage of yeast-to-hypha transition. In addition, when C. albicans was co-cultured with THP-1 human monocytes, the engulfed C. albicans was developing hypha efficiently within 1 hr and the expression of hypha-associated Sap proteins could be detected on the distal surface of hyphae.

CONCLUSION

We propose that the glucose level of bloodstream (approximately 0.1%) may be facilitated for stimulation of C. albicans to develop invasive hypha-form and to elicit promptly production of high-level hypha-associated Sap proteins.

Historical trends in the epidemiology of candidaemia: analysis of an 11-year period in a tertiary care hospital in Brazil

Candida species are an important cause of bloodstream infections (BSI). To evaluate the epidemiological, clinical and microbiological aspects of two cohorts {1994-1999 [period 1 (P1) ]; 2000-2004 [period 2 (P2) ]} of candidaemic patients, we performed a retrospective analysis from a laboratory-based survey. A total of 388 candidaemias were identified, with an incidence of 0.20/1,000 patient-days and a significant increase in P2 vs. P1 (0.25 vs. 0.15, p = 0.04). Cancer and prior antibiotic use were frequent and Candida albicans was the most prevalent species found (42.4%). Resistance to fluconazole was found in 2.47% of the strains. No differences were observed in the species distribution of Candida during the study periods. In the P2 cohort, there were higher prevalence of elderly individuals, cardiac, pulmonary and liver diseases, renal failure, central venous catheters and antibiotic therapy. In P1, there were higher prevalence of neurological diseases and chemotherapy. The crude mortality was 55.4%. In conclusion, our incidence rates remained high. Furthermore, the distribution pattern of Candida species and the fluconazole resistance profile remained unchanged. Moreover, we found a clear trend of higher prevalence of candidaemia among the elderly and among patients with comorbidities. Finally, it is necessary to discuss strategies for the prevention and control of Candida BSI in Brazil.

Sap6, a secreted aspartyl proteinase, participates in maintenance the cell surface integrity of Candida albicans

Background

The polymorphic species Candida albicans is the major cause of candidiasis in humans. The secreted aspartyl proteinases (Saps) of C. albicans, encoded by a family of 10 SAP genes, have been investigated as the virulent factors during candidiasis. However, the biological functions of most Sap proteins are still uncertain. In this study, we applied co-culture system of C. albicans and THP-1 human monocytes to explore the pathogenic roles and biological functions of Sap proteinases.

Results

After 1 hr of co-culture of C. albicans strains and THP-1 human monocytes at 37°C, more than 60% of the THP-1-engulfed wild type and Δsap5 Candida cells were developing long hyphae. However, about 50% of THP-1-engulfed Δsap6 Candida cells were generating short hyphae, and more dead Candida cells were found in Δsap6 strain that was ingested by THP-1 cells (about 15% in Δsap6 strain vs. 2 ~ 2.5% in SC5314 and Δsap5 strains). The immunofluorescence staining demonstrated that the Sap6 is the major hyphal tip located Sap protein under THP-1 phagocytosis. The sap6-deleted strains (Δsap6, Δsap4/6, and Δsap5/6) appeared slower growth on Congo red containing solid medium at 25°C, and the growth defect was exacerbated when cultured at 37°C in Congo red or SDS containing medium. In addition, more proteins were secreted from Δsap6 strain and the β-mercaptoethanol (β-ME) extractable surface proteins from Δsap6 mutant were more abundant than that of extracted from wild type strain, which included the plasma membrane protein (Pma1p), the ER-chaperone protein (Kar2p), the protein transport-related protein (Arf1p), the cytoskeleton protein (Act1), and the mitochondrial outer membrane protein (porin 1). Moreover, the cell surface accessibility was increased in sap6-deleted strains.

Conclusion

From these results, we speculated that the cell surface constitution of C. albicans Δsap6 strain was defect. This may cause the more accessible of β-ME to disulfide-bridged cell surface components and may weaken the resistance of Δsap6 strain encountering phagocytosis of THP-1 cells. Sap6 protein displays a significant function involving in maintenance the cell surface integrity.

Candida glabrata: a review of its features and resistance

Candida species belong to the normal microbiota of the oral cavity and gastrointestinal and vaginal tracts, and are responsible for several clinical manifestations, from mucocutaneous overgrowth to bloodstream infections. Once believed to be non-pathogenic, Candida glabrata was rapidly blamable for many human diseases. Year after year, these pathological circumstances are more recurrent and problematic to treat, especially when patients reveal any level of immunosuppression. These difficulties arise from the capacity of C. glabrata to form biofilms and also from its high resistance to traditional antifungal therapies. Thus, this review intends to present an excerpt of the biology, epidemiology, and pathology of C. glabrata, and detail an approach to its resistance mechanisms based on studies carried out up to the present.

Changing epidemiology of candidemia in a medical center in middle Taiwan

BACKGROUND

Candidemia remains a major cause of morbidity and mortality in the health care setting, and the epidemiology of Candida infection is changing.

METHODS

Clinical and laboratory data from patients with candidemia were collected retrospectively at a tertiary medical center in Taiwan from July 1, 2009 to June 30, 2012 (a 36-month period). Demographics, clinical characteristics, and drug susceptibility of the invading Candida species of patients at the onset of candidemia were analyzed and compared with previous study from January 1, 2001 to June 30, 2003 (a 30-month period).

RESULTS

A total of 209 episodes of candidemia in 205 patients were identified in this study period. When compared with the previous study period, more patients were admitted for medical conditions at percentages ranging from 49.5% to 69.8%; the incidence rate of health care-associated candidemia increased from 0.76 to 1.14 per 1000 discharges; the proportion of Candida albicans in patients with candidemia decreased from 64.8% to 43.6% whereas the proportion of Candida glabrata increased greatly from 1.1% to 21.6% and the proportions of Candida tropicalis and Candida parapsilosis were slightly elevated (19.8-22.0% and 2.2-7.3%, respectively). All of the C. albicans isolates remained susceptible to fluconazole, whereas 66.7% of C. glabrata isolates were dose-dependent susceptible, and 4.4% of C. glabrata isolates and 11.6% C. tropicalis isolates were resistant. There was one C. glabrata and one Candida guilliermondii resistant to echinocandin. The predictors for 30-day mortality included the high Acute Physiology and Chronic Health Evaluation II (APACHE II) score, use of parenteral nutrition, underlying malignancy, liver cirrhosis, and neutropenia whereas candidemia by C. parapsilosis or C. glabrata is a favorable predictor when compared with C. albicans.

CONCLUSION

The distribution of Candida species in candidemia was changed. Although C. albicans remained the major species, the isolation of non-C. albicans spp., especially C. glabrata, increased. Patients with candidemia still had high mortalities due to severity of illness and underlying conditions.

Genotype analysis based on intergenic spacer 1 sequences of Trichosporon asahii collected in Taiwan

Among 32 Trichosporon asahii isolates collected in four rounds of the Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) studies, conducted in 1999, 2002, 2006, and 2010, five different intergenic spacer 1 (IGS1) genotypes were detected. Genotype 1 was the most common (43.8%), followed by genotypes 3 (28.1%), 7 (12.5%), 5 (9.4%), and 4 (6.3%). Interestingly, genotype 7 was more prevalent in Taiwan than in other areas (P = 0.01); while we did not find a significant association between IGS1 genotype and susceptibility to antifungal drugs, we did note that the majority of isolates of T. asahii were susceptible to both fluconazole and voriconazole, consistent with previous reports. A higher proportion of isolates (P = 0.05) collected in 2010 (4/12, 33.3%) had high amphotericin B MICs (≥ 2 mg/l) than those collected in the previous three TSARYs (1/21, 5%). Hence, the new data of genotypes and drug susceptibilities in the present study may contribute to the epidemiology of T. asahii.

Distribution and drug susceptibilities of Candida species causing candidemia from a medical center in central Taiwan

Invasive fungal infections have increased significantly in the past few decades because of the increase in high-risk populations. To investigate the distribution and drug susceptibilities of such infections, we analyzed all 152 Candida isolates causing candidemia from 2004 to 2006 at the China Medical University Hospital, a medical center in central Taiwan. Candida albicans was the most common species, accounting for 52.6% of the isolates, followed by C. tropicalis (19.7%), C. parapsilosis (14.5%), C. glabrata (8.6%), C. guilliermondii (3.9%), and C. pelliculosa (0.7%). All isolates were susceptible to amphotericin B, anidulafungin, micafungin, and voriconazole according to minimum inhibitory concentrations (MICs) after a 24-h incubation; 0.7%, 6.6%, and 7.9% of isolates were resistant to amphotericin B, fluconazole, and voriconazole, respectively, after 48-h incubation. Both C. albicans and C. parapsilosis had high degrees of agreement for azoles between 24- and 48-h incubation periods, whereas C. glabrata (38.5-46.2%) and C. tropicalis (56.7-63.3%) did not. The majority of the isolates with high azole MICs displayed a trailing growth phenotype. Hence, the MICs of different drugs after 24-h incubation may be considered for prognosis of candidemia.

Intravenous anidulafungin followed optionally by oral voriconazole for the treatment of candidemia in Asian patients: results from an open-label Phase III trial

Background

Candidemia is a significant cause of morbidity and mortality in hospitalized patients, particularly in Asia. Anidulafungin has been reported to be an effective treatment for candidemia in Western populations, but little is known about its efficacy in Asian patients, where the clinical presentation and epidemiology may be different.

Methods

An open-label study of anidulafungin for the treatment of candidemia was recently conducted in several Asian countries. Treatment was initiated with intravenous anidulafungin, given for at least 5 days, with the option to complete treatment with oral voriconazole. The primary endpoint was global (clinical and microbiological) response, and the primary analysis was the proportion of patients in the modified intent-to-treat population with successful global response at the end of therapy. Secondary analyses included proportion with successful global response in clinically relevant patient subgroups. The safety and tolerability profile of anidulafungin and voriconazole in this population was also investigated.

Results

Forty-three patients were studied, including 42 in the modified intent-to-treat population. Eighteen patients were > 65 years, the largest age subgroup, and 21 had central venous catheters. The most common Candida species causing infection were C. tropicalis (n = 18) and C. albicans (n = 10). In the primary analysis, 73.8% had a successful global response at end of therapy. Success rates in subgroups were: 72.2% for C. tropicalis and 71.4% for C. albicans infection, 58.8% for patients > 65 years, and 81.0% for patients with central venous catheters. Safety and tolerability were comparable with the known profiles for anidulafungin (and voriconazole).

Conclusions

Although the epidemiology of Candida infections was different in this open-label study, the efficacy of anidulafungin in Asian patients with documented candidemia was consistent with previous studies in Western populations. No new safety concerns were identified.

Trial registration

http://www.clinicaltrials.gov identifier NCT00537329

Small-molecule suppressors of Candida albicans biofilm formation synergistically enhance the antifungal activity of amphotericin B against clinical Candida isolates

A new class of fungal biofilm inhibitors represented by shearinines D (3) and E (4) were obtained from a Penicillium sp. isolate. The inhibitory activities of 3 and 4 were characterized using a new imaging flow-cytometer technique, which enabled the rapid phenotypic analysis of Candida albicans cell types (budding yeast cells, germ tube cells, pseudohyphae, and hyphae) in biofilm populations. The results were confirmed by experimental data obtained from three-dimensional confocal laser scanning microscopy and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assays. These data indicate that 3 and 4 inhibited C. albicans biofilm formation by blocking the outgrowth of hyphae at a relatively late stage of biofilm development (IC50 = 8.5 and 7.6 μM, respectively). However, 3 and 4 demonstrated comparatively weak activity at disrupting existing biofilms. Compounds 3 and 4 also exhibited synergistic activities with amphotericin B against C. albicans and other clinical Candida isolates by enhancing the potency of amphotericin B up to 8-fold against cells in both developing and established biofilms. These data suggest that the Candida biofilm disruption and amphotericin B potentiating effects of 3 and 4 could be mediated through multiple biological targets. The shearinines are good tools for testing the potential advantages of using adjunctive therapies in combination with antifungals.

Species distribution and drug susceptibilities of Candida isolates in TSARY 2010

Susceptibilities to antifungal drugs of 1083 Candida isolates collected in Taiwan Surveillance of Antimicrobial Resistance of Yeasts in 2010 were determined. There were 422 (39%) C. albicans, 270 (24.9%) C. tropicalis, 258 (23.8%) C. glabrata, 87 (8%) C. parapsilosis, 18 (1.7%) C. krusei, and 28 (2.6%) of 13 other species. In the present study, we have applied species-specific clinical breakpoints for common species and epidemiological cutoff values for rare species. We found that majority of isolates were susceptible to tested drugs. A total of 15, 3, 2, and 0 isolates were not susceptible to fluconazole, voriconazole, amphotericin B, and anidulafungin, respectively. We found that three of the four fluconazole non-susceptible C. albicans isolates were resistant to voriconazole. Hence, there is an issue of cross-resistance among azole-type drugs.

Mechanisms of azole resistance in 52 clinical isolates of Candida tropicalis in China

OBJECTIVES

To explore the mechanisms underlying azole resistance in clinical isolates of Candida tropicalis collected in China by focusing on their efflux pumps, respiratory status and azole antifungal target enzyme.

METHODS

Fifty-two clinical isolates of C. tropicalis were collected from five hospitals in four provinces of China and antifungal susceptibility tests were performed. Rhodamine 6G and rhodamine 123 were used to investigate the efflux pumps and respiratory status, respectively. Transporter-related genes CDR1 and MDR1, mitochondrial gene CYTb, as well as ERG11, were quantified by real-time RT-PCR. Meanwhile, ergosterol content was analysed using liquid chromatography-mass spectrometry/mass spectrometry. An ERG11-deficient (erg11Δ) Saccharomyces cerevisiae strain was generated to study the function of mutations in ERG11.

RESULTS

MICs showed that 31 isolates were resistant to at least one type of azole antifungal. Flow cytometry using rhodamine 123 revealed increased respiration for the azole-resistant isolates, but CYTb was not overexpressed. No significant difference in the efflux of rhodamine 6G was found, which was consistent with the comparable expression levels of CDR1 and MDR1. In contrast, the azole-resistant isolates overexpressed ERG11 and showed increased ergosterol content. Moreover, the isolates resistant to three azole antifungals expressed higher levels of ERG11 mRNA than those resistant to only fluconazole or itraconazole. Two ERG11 mutations, Y132F and S154F, were found in azole-resistant isolates and could be shown to mediate azole resistance by expression in S. cerevisiae.

CONCLUSIONS

The up-regulation and mutations of ERG11 mediate azole resistance of C. tropicalis.