Epidemiology of invasive candidiasis

The Wsc1p cell wall signaling protein controls biofilm (Mat) formation independently of Flo11p in Saccharomyces cerevisiae

Saccharomyces cerevisiae strains of the ∑1278b background generate biofilms, referred to as mats, on low-density agar (0.3%) plates made with rich media (YPD). Mat formation involves adhesion of yeast cells to the surface of the agar substrate and each other as the biofilm matures, resulting in elaborate water channels that create filigreed patterns of cells. The cell wall adhesion protein Flo11p is required for mat formation; however, genetic data indicate that other unknown effectors are also required. For example, mutations in vacuolar protein sorting genes that affect the multivesicular body pathway, such as vps27Δ, cause mat formation defects independently of Flo11p, presumably by affecting an unidentified signaling pathway. A cell wall signaling protein, Wsc1p, found at the plasma membrane is affected for localization and function by vps27Δ. We found that a wsc1 mutation disrupted mat formation in a Flo11p-independent manner. Wsc1p appears to impact mat formation through the Rom2p-Rho1p signaling module, by which Wsc1p also regulates the cell wall. The Bck1p, Mkk1/Mkk2, Mpk1p MAP kinase signaling cascade is known to regulate the cell wall downstream of Wsc1p-Rom2p-Rho1p but, surprisingly, these kinases do not affect mat formation. In contrast, Wsc1p may impact mat formation by affecting Skn7p instead. Skn7p can also receive signaling inputs from the Sln1p histidine kinase; however, mutational analysis of specific histidine kinase receiver residues in Skn7p indicate that Sln1p does not play an important role in mat formation, suggesting that Skn7p primarily acts downstream of Wsc1p to regulate mat formation.

Development and validation of an in-house database for matrix-assisted laser desorption ionization-time of flight mass spectrometry-based yeast identification using a fast protein extraction procedure

In recent studies evaluating the usefulness of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based identification of yeasts for the routine diagnosis of fungal infections, preanalytical sample processing has emerged as a critical step for reliable MALDI-TOF MS outcomes, especially when the Bruker Daltonics Biotyper software was used. In addition, inadequate results often occurred due to discrepancies between the methods used for clinical testing and database construction. Therefore, we created an in-house MALDI-TOF MS library using the spectra from 156 reference and clinical yeast isolates (48 species in 11 genera), which were generated with a fast sample preparation procedure. After a retrospective validation study, our database was evaluated on 4,232 yeasts routinely isolated during a 6-month period and fast prepared for MALDI-TOF MS analysis. Thus, 4,209 (99.5%) of the isolates were successfully identified to the species level (with scores of ≥2.0), with 1,676 (39.6%) having scores of >2.3. For the remaining 23 (0.5%) isolates, no reliable identification (with scores of <1.7) was obtained. Interestingly, these isolates were almost always from species uniquely represented or not included in the database. As the MALDI-TOF MS results were, except for 23 isolates, validated without additional phenotypic or molecular tests, our proposed strategy can enhance the rapidity and accuracy of MALDI-TOF MS in identifying medically important yeast species. However, while continuous updating of our database will be necessary to enrich it with more strains/species of new and emerging yeasts, the present in-house MALDI-TOF MS library can be made publicly available for future multicenter studies.

Update on antifungal resistance in Aspergillus and Candida

Antifungal resistance in Candida and Aspergillus may be either intrinsic or acquired and may be encountered in the antifungal drug exposed but also the antifungal drug-naïve patient. Prior antifungal treatment confers a selection pressure and notoriously raises the awareness of possible resistance in patients failing therapy, thus calling for susceptibility testing. On the contrary, antifungal resistance in the drug-naïve patient is less expected and therefore more challenging. This is particularly true when it concerns pathogens with acquired resistance which cannot be predicted from the species identification itself. This scenario is particularly relevant for A. fumigatus infections due to the increasing prevalence of azole-resistant isolates in the environment. For Candida, infections resistance is most common in the context of increasing prevalence of species with intrinsic resistance. Candida glabrata which has intrinsically reduced susceptibility to fluconazole is increasingly common particularly among the adult and elderly population on the Northern Hemisphere where it may be responsible for as many as 30% of the blood stream infections in population-based surveillance programmes. Candida parapsilosis is prevalent in the paediatric setting, at centres with increasing echinocandin use and at the southern or pacific parts of the world. In the following, the prevalence and drivers of intrinsic and acquired resistance in Aspergillus and Candida will be reviewed.

Breakpoints for antifungal agents: an update from EUCAST focussing on echinocandins against Candida spp. and triazoles against Aspergillus spp

Candida and Aspergillus infections have emerged as significant pathogens in recent decades. During this same time, broad spectrum triazole and echinocandin antifungal agents have been developed and increasingly used. One consequence of widespread use is leading to the emergence of mutants with acquired resistance mutations. Therefore, accurate susceptibility testing and appropriate clinical breakpoints for the interpretation of susceptibility results have become increasingly important. Here we review the underlying methodology by which breakpoints have been selected by EUCAST (European Committee on Antimicrobial Susceptibility Testing). Five parameters are evaluated: dosing regimens used; EUCAST MIC distributions from multiple laboratories, species and compound specific epidemiological cut off values (upper MIC limits of wild type isolates or ECOFFs), pharmacokinetic/pharmacodynamic relationships and targets associated with outcome and finally clinical data by species and MIC when available. The general principles are reviewed followed by a detailed review of the individual aspects for Candida species and the three echinocandins and for Aspergillus and the three mould-active azoles. This review provides an update of the subcommittee on antifungal susceptibility testing (AFST) of the EUCAST methodology and summarises the current EUCAST breakpoints for Candida and Aspergillus. Recommendations about applicability of antifungal susceptibility testing in the routine setting are also included.

Epidemiology of candidemia in Qatar, the Middle East: performance of MALDI-TOF MS for the identification of Candida species, species distribution, outcome, and susceptibility pattern

INTRODUCTION

Bloodstream infections (BSIs) due to Candida spp. constitute the predominant group of hospital-based fungal infections worldwide. A retrospective study evaluated the performance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of BSI Candida isolates. The epidemiology, risk factors, demographic features, species distribution, and clinical outcome associated with candidemia in patients admitted to a single tertiary-care hospital in Qatar, were analyzed.

METHODS

A single-center, retrospective analysis covering the period from January 1, 2004 to December 31, 2010 was performed. Molecular identification used sequence analysis of the D1/D2 domains of the large subunit ribosomal DNA (LSU rDNA) and the ITS1/2 regions of the rDNA. MALDI-TOF MS-based identification of all yeast isolates was performed with the ethanol/formic acid extraction protocol according to Bruker Daltonics (Bremen, Germany). The susceptibility profiles of 201 isolates to amphotericin B, itraconazole, fluconazole, voriconazole, anidulafungin, caspofungin, posaconazole, and isavuconazole were tested using CLSI standard broth microdilution method (M27-A3 and M27 S4) guidelines. Statistical analyses were performed with the statistical package SPSS 19.0.

RESULTS

A total of 187 patients with 201 episodes of candidemia were identified. Candida albicans was the most common species isolated (33.8 %; n = 68), whereas non-albicans Candida species represented 66.2 % (n = 133) of the episodes. The species distribution and outcome of candidemia showed a difference in the crude mortality between patients infected with C. albicans (n = 30; 45.5 %) and non-albicans Candida species. For example, C. parapsilosis candidemia was associated with the lowest mortality rate (40.6 %), and patients with other non-albicans species had the highest mortality rate (68-71.4 %). High mortality rates were observed among pediatric (<1 year of age) and elderly patients (>60 years of age). All strains showed low minimum inhibitory concentrations (MICs) (MIC90 of 0.063 μg/ml) to isavuconazole. The overall resistance to voriconazole in vitro antifungal activity was 2.5 %. C. glabrata (n = 38) had an MIC90 of 8 μg/ml for fluconazole. Most yeast isolates were susceptible to anidulafungin (>99.5 %) and 81.1 % to caspofungin. Resistance to anidulafungin was detected in 1/8 (12.5 %) isolates of C. orthopsilosis. According to new Clinical and Laboratory Standards Institute (CLSI) breakpoints, C. glabrata (n = 38) showed 100 % resistance, and 37/68 (54.4 %) C. albicans isolates were susceptible dose dependent (SDD) to caspofungin. Identification by MALDI-TOF MS was in 100 % concordance with molecular identification.

CONCLUSION

The Middle East epidemiology of candidemia has a unique species distribution pattern distinct from other parts of the globe. High mortality rates were observed among pediatric (<1 year of age) and elderly patients (>60 years of age). All strains were susceptible to isavuconazole. All isolates of C.glabrata were resistant to caspofungin based on M27 S4. MALDI-TOF MS is a highly useful method for the routine identification of yeast isolates in clinical setting to achieve successful therapeutic treatment.

In vitro antifungal activity of farnesyltransferase inhibitors against clinical isolates of Aspergillus and Candida

Background

Protein farnesylation is an important tosttranslational modification in fungi. We evaluated the antifungal activity of two farnesyltransferase inhibitors against clinical isolates of Aspergillus and Candida.

Methods

Disk diffusion assay and broth microdilution assay were used to determine the antifungal susceptibility of two farnesyltransferase inhibitors (manumycin A and tipifarnib) against clinical isolates of Aspergillus and Candida.

Results

Disk diffusion assay demonstrated both agents had activity against Aspergillus and Candida. The minimal inhibitory concentration (MIC) ranges for manumycin A against Aspergillus and Candida were 200 to 400 μM and 13 to >25 μM, respectively. Unfortunately, the MIC were vastly higher than the concentrations that inhibit the proliferation and viability of mammalian cells. The MICs of tipifarnib against Aspergillus and Candida were >1600 μM.

Conclusion

The outcome of present study showed that farnesyltransferase inhibitors have activity against Aspergillus and Candida. This suggests that farnesyltransferase may be used as anifungal target in designing and developing new drugs.

Distinct roles of Candida albicans drug resistance transcription factors TAC1, MRR1, and UPC2 in virulence

Azoles are widely used in antifungal therapy in medicine. Resistance to azoles can occur in Candida albicans principally by overexpression of multidrug transporter gene CDR1, CDR2, or MDR1 or by overexpression of ERG11, which encodes the azole target. The expression of these genes is controlled by the transcription factors (TFs) TAC1 (involved in the control of CDR1 and CDR2), MRR1 (involved in the control of MDR1), and UPC2 (involved in the control of ERG11). Several gain-of-function (GOF) mutations are present in hyperactive alleles of these TFs, resulting in the overexpression of target genes. While these mutations are beneficial to C. albicans survival in the presence of the antifungal drugs, their effects could potentially alter the fitness and virulence of C. albicans in the absence of the selective drug pressure. In this work, the effect of GOF mutations on C. albicans virulence was addressed in a systemic model of intravenous infection by mouse survival and kidney fungal burden assays. We engineered a set of strains with identical genetic backgrounds in which hyperactive alleles were reintroduced in one or two copies at their genomic loci. The results obtained showed that neither TAC1 nor MRR1 GOF mutations had a significant effect on C. albicans virulence. In contrast, the presence of two hyperactive UPC2 alleles in C. albicans resulted in a significant decrease in virulence, correlating with diminished kidney colonization compared to that by the wild type. In agreement with the effect on virulence, the decreased fitness of an isolate with UPC2 hyperactive alleles was observed in competition experiments with the wild type in vivo but not in vitro. Interestingly, UPC2 hyperactivity delayed filamentation of C. albicans after phagocytosis by murine macrophages, which may at least partially explain the virulence defects. Combining the UPC2 GOF mutation with another hyperactive TF did not compensate for the negative effect of UPC2 on virulence. In conclusion, among the major TFs involved in azole resistance, only UPC2 had a negative impact on virulence and fitness, which may therefore have consequences for the epidemiology of antifungal resistance.

Candida nivariensis isolated from a renal transplant patient with persistent candiduria-Molecular identification using ITS PCR and MALDI-TOF

We report on the isolation of Candida nivariensis from a renal transplant patient with persistent candiduria. Biochemical profiling misidentified isolates as Candida glabrata (3/5) and Candida inconspicua (2/5). All isolates produced white colonies on CHROMagar^™ Candida medium. Internal transcribed spacer (ITS) ribosomal gene sequence analysis and MALDI-TOF-MS analysis (Bruker Biotyper^™ 2.0) identified all isolates as C. nivariensis, demonstrating the utility of MALDI-TOF as a rapid, accurate approach for the identification of cryptic Candida species.

MALDI-TOF mass spectrometry in the clinical mycology laboratory: identification of fungi and beyond

MALDI-TOF mass spectrometry (MS) is becoming essential in most clinical microbiology laboratories throughout the world. Its successful use is mainly attributable to the low operational costs, the universality and flexibility of detection, as well as the specificity and speed of analysis. Based on characteristic protein spectra obtained from intact cells - by means of simple, rapid and reproducible preanalytical and analytical protocols - MALDI-TOF MS allows a highly discriminatory identification of yeasts and filamentous fungi starting from colonies. Whenever used early, direct identification of yeasts from positive blood cultures has the potential to greatly shorten turnaround times and to improve laboratory diagnosis of fungemia. More recently, but still at an infancy stage, MALDI-TOF MS is used to perform strain typing and to determine antifungal drug susceptibility. In this article, the authors discuss how the MALDI-TOF MS technology is destined to become a powerful tool for routine mycological diagnostics.

Invasive candidiasis as a cause of sepsis in the critically ill patient

Invasive fungal infections are an increasingly frequent etiology of sepsis in critically ill patients causing substantial morbidity and mortality. Candida species are by far the predominant agent of fungal sepsis accounting for 10% to 15% of health-care associated infections, about 5% of all cases of severe sepsis and septic shock and are the fourth most common bloodstream isolates in the United States. One-third of all episodes of candidemia occur in the intensive care setting. Early diagnosis of invasive candidiasis is critical in order to initiate antifungal agents promptly. Delay in the administration of appropriate therapy increases mortality. Unfortunately, risk factors, clinical and radiological manifestations are quite unspecific and conventional culture methods are suboptimal. Non-culture based methods (such as mannan, anti-mannan, β-d-glucan, and polymerase chain reaction) have emerged but remain investigational or require additional testing in the ICU setting. Few prophylactic or pre-emptive studies have been performed in critically ill patients. They tended to be underpowered and their clinical usefulness remains to be established under most circumstances. The antifungal armamentarium has expanded considerably with the advent of lipid formulations of amphotericin B, the newest triazoles and the echinocandins. Clinical trials have shown that the triazoles and echinocandins are efficacious and well tolerated antifungal therapies. Clinical practice guidelines for the management of invasive candidiasis have been published by the European Society for Clinical Microbiology and Infectious Diseases and the Infectious Diseases Society of North America.

Comparative evaluation of BD Phoenix and vitek 2 systems for species identification of common and uncommon pathogenic yeasts

The BD Phoenix system was evaluated for species-level identification of yeasts (250 clinical isolates) and compared with the Vitek 2 system, using ribosomal internal transcribed spacer (ITS) sequence analysis as the gold standard. Considering only the species included in each system's database, 96.3% (236/245) and 91.4% (224/245) of the isolates were correctly identified by BD Phoenix and Vitek 2, respectively.

ÉPICO project. Development of educational recommendations using the DELPHI technique on invasive candidiasis in non-neutropenic critically ill adult patients

BACKGROUND

Although there has been an improved management of invasive candidiasis in the last decade, controversial issues still remain, especially in the diagnostic and therapeutic approaches.

AIMS

We sought to identify the core clinical knowledge and to achieve high level agreement recommendations required to care for critically ill adult patients with invasive candidiasis.

METHODS

A prospective Spanish survey reaching consensus by the DELPHI technique was made. It was anonymously conducted by electronic mail in a first term to 25 national multidisciplinary experts in invasive fungal infections from five national scientific societies, including intensivists, anesthesiologists, microbiologists, pharmacologists and infectious diseases specialists, who answered to 47 questions prepared by a coordination group after a strict review of the literature in the last five years. The educational objectives spanned five categories, including epidemiology, diagnostic tools, prediction rules, and treatment and de-escalation approaches. The level of agreement achieved among the panel experts in each item should exceed 75% to be selected. In a second term, after extracting recommendations from the selected items, a face to face meeting was performed where more than 80 specialists in a second round were invited to validate the preselected recommendations.

RESULTS

In the first term, 20 recommendations were preselected (Epidemiology 4, Scores 3, Diagnostic tools 4, Treatment 6 and De-escalation approaches 3). After the second round, the following 12 were validated: (1) Epidemiology (2 recommendations): think about candidiasis in your Intensive Care Unit (ICU) and do not forget that non-Candida albicans-Candida species also exist. (2) Diagnostic tools (4 recommendations): blood cultures should be performed under suspicion every 2-3 days and, if positive, every 3 days until obtaining the first negative result. Obtain sterile fluid and tissue, if possible (direct examination of the sample is important). Use non-culture based methods as microbiological tools, whenever possible. Determination of antifungal susceptibility is mandatory. (3) Scores (1 recommendation): as screening tool, use the Candida Score and determine multicolonization in high risk patients. (4) Treatment (4 recommendations): start early. Choose echinocandins. Withdraw any central venous catheter. Fundoscopy is needed. (5) De-escalation (1 recommendation): only applied when knowing susceptibility determinations and after 3 days of clinical stability. The higher rate of agreement was achieved in the optimization of microbiological tools and the withdrawal of the catheter, whereas the lower rate corresponded to de-escalation therapy and the use of scores.

CONCLUSIONS

The management of invasive candidiasis in ICU patients requires the application of a broad range of knowledge and skills that we summarize in our recommendations. These recommendations may help to identify the potential patients, standardize their global management and improve their outcomes, based on the DELPHI methodology.

Rapid antifungal susceptibility testing by matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis

The widespread use of antifungal agents, which is likely to expand with their enhanced availability, has promoted the emergence of drug-resistant strains. Antifungal susceptibility testing (AFST) is now an essential procedure for guiding appropriate antifungal therapy. Recently, we developed a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based method that enables the detection of fungal isolates with reduced echinocandin susceptibility, relying on the proteome changes that are detectable after a 15-h exposure of fungal cells to serial drug concentrations. Here, we describe a simplified version of this approach that facilitates discrimination of the susceptible and resistant isolates of Candida albicans after a 3-h incubation in the presence of "breakpoint" level drug concentrations of the echinocandin caspofungin (CSF). Spectra at concentrations of 0 (null), 0.03 (intermediate), and 32 (maximal) μg/ml of CSF were used to create individual composite correlation index (CCI) matrices for 65 C. albicans isolates, including 13 fks1 mutants. Isolates are then classified as susceptible or resistant to CSF if the CCI values of spectra at 0.03 and 32 μg/ml are higher or lower, respectively, than the CCI values of spectra at 0.03 and 0 μg/ml. In this way, the drug resistance of C. albicans isolates to echinocandin antifungals can be quickly assessed. Furthermore, the isolate categorizations determined using MALDI-TOF MS-based AFST (ms-AFST) were consistent with the wild-type and mutant FKS1 genotypes and the AFST reference methodology. The ms-AFST approach may provide a rapid and reliable means of detecting emerging antifungal resistance and accelerating the initiation of appropriate antifungal treatment.

[Épico project: Development of educational recommendations using the DELPHI technique on invasive candidiasis in non-neutropenic critically ill adult patients. Grupo Proyecto Épico]

BACKGROUND

Although there has been an improved management of invasive candidiasis in the last decade, controversial issues still remain, especially in the diagnostic and therapeutic approaches.

AIMS

We sought to identify the core clinical knowledge and to achieve high level agreement recommendations required to care for critically ill adult patients with invasive candidiasis.

METHODS

A prospective Spanish survey reaching consensus by the DELPHI technique was made. It was anonymously conducted by electronic mail in a first term to 25 national multidisciplinary experts in invasive fungal infections from five national scientific societies, including intensivists, anesthesiologists, microbiologists, pharmacologists and infectious diseases specialists, who answered to 47 questions prepared by a coordination group after a strict review of the literature in the last five years. The educational objectives spanned five categories, including epidemiology, diagnostic tools, prediction rules, and treatment and de-escalation approaches. The level of agreement achieved among the panel experts in each item should exceed 75% to be selected. In a second term, after extracting recommendations from the selected items, a face to face meeting was performed where more than 80 specialists in a second round were invited to validate the preselected recommendations.

RESULTS

In the first term, 20 recommendations were preselected (Epidemiology 4, Scores 3, Diagnostic tools 4, Treatment 6 and De-escalation approaches 3). After the second round, the following 12 were validated: (1) Epidemiology (2 recommendations): think about candidiasis in your Intensive Care Unit (ICU) and do not forget that non-Candida albicans-Candida species also exist. (2) Diagnostic tools (4 recommendations): blood cultures should be performed under suspicion every 2-3 days and, if positive, every 3 days until obtaining the first negative result. Obtain sterile fluid and tissue, if possible (direct examination of the sample is important). Use non-culture based methods as microbiological tools, whenever possible. Determination of antifungal susceptibility is mandatory. (3) Scores (1 recommendation): as screening tool, use the Candida Score and determine multicolonization in high risk patients. (4) Treatment (4 recommendations): start early. Choose echinocandins. Withdraw any central venous catheter. Fundoscopy is needed. (5) De-escalation (1 recommendation): only applied when knowing susceptibility determinations and after 3 days of clinical stability. The higher rate of agreement was achieved in the optimization of microbiological tools and the withdrawal of the catheter, whereas the lower rate corresponded to de-escalation therapy and the use of scores.

CONCLUSIONS

The management of invasive candidiasis in ICU patients requires the application of a broad range of knowledge and skills that we summarize in our recommendations. These recommendations may help to identify the potential patients, standardize their global management and improve their outcomes, based on the DELPHI methodology.

Echinocandin and triazole antifungal susceptibility profiles for clinical opportunistic yeast and mold isolates collected from 2010 to 2011: application of new CLSI clinical breakpoints and epidemiological cutoff values for characterization of geographic and temporal trends of antifungal resistance

The SENTRY Antimicrobial Surveillance Program monitors global susceptibility and resistance rates of newer and established antifungal agents. We report the echinocandin and triazole antifungal susceptibility patterns for 3,418 contemporary clinical isolates of yeasts and molds. The isolates were obtained from 98 laboratories in 34 countries during 2010 and 2011. Yeasts not presumptively identified by CHROMagar, the trehalose test, or growth at 42°C and all molds were sequence identified using internal transcribed spacer (ITS) and 28S (yeasts) or ITS, translation elongation factor (TEF), and 28S (molds) genes. Susceptibility testing was performed against 7 antifungals (anidulafungin, caspofungin, micafungin, fluconazole, itraconazole, posaconazole, and voriconazole) using CLSI methods. Rates of resistance to all agents were determined using the new CLSI clinical breakpoints and epidemiological cutoff value criteria, as appropriate. Sequencing of fks hot spots was performed for echinocandin non-wild-type (WT) strains. Isolates included 3,107 from 21 Candida spp., 146 from 9 Aspergillus spp., 84 from Cryptococcus neoformans, 40 from 23 other mold species, and 41 from 9 other yeast species. Among Candida spp., resistance to the echinocandins was low (0.0 to 1.7%). Candida albicans and Candida glabrata that were resistant to anidulafungin, caspofungin, or micafungin were shown to have fks mutations. Resistance to fluconazole was low among the isolates of C. albicans (0.4%), Candida tropicalis (1.3%), and Candida parapsilosis (2.1%); however, 8.8% of C. glabrata isolates were resistant to fluconazole. Among echinocandin-resistant C. glabrata isolates from 2011, 38% were fluconazole resistant. Voriconazole was active against all Candida spp. except C. glabrata (10.5% non-WT), whereas posaconazole showed decreased activity against C. albicans (4.4%) and Candida krusei (15.2% non-WT). All agents except for the echinocandins were active against C. neoformans, and the triazoles were active against other yeasts (MIC90, 2 μg/ml). The echinocandins and triazoles were active against Aspergillus spp. (MIC90/minimum effective concentration [MEC90] range, 0.015 to 2 μg/ml), but the echinocandins were not active against other molds (MEC90 range, 4 to >16 μg/ml). Overall, echinocandin and triazole resistance rates were low; however, the fluconazole and echinocandin coresistance among C. glabrata strains warrants continued close surveillance.

Épico Project. Development of educational recommendations using the DELPHI technique on invasive candidiasis in non-neutropenic critically ill adult patients

BACKGROUND

Although there has been an improved management of invasive candidiasis in the last decade, controversial issues still remain, especially in the diagnostic and therapeutic approaches.

AIMS

We sought to identify the core clinical knowledge and to achieve high level agreement recommendations required to care for critically ill adult patients with invasive candidiasis.

METHODS

A prospective Spanish survey reaching consensus by the DELPHI technique was made. It was anonymously conducted by electronic mail in a first term to 25 national multidisciplinary experts in invasive fungal infections from five national scientific societies, including intensivists, anesthesiologists, microbiologists, pharmacologists and infectious diseases specialists, who answered to 47 questions prepared by a coordination group after a strict review of the literature in the last five years. The educational objectives spanned five categories, including epidemiology, diagnostic tools, prediction rules, and treatment and de-escalation approaches. The level of agreement achieved among the panel experts in each item should exceed 75% to be selected. In a second term, after extracting recommendations from the selected items, a face to face meeting was performed where more than 80 specialists in a second round were invited to validate the preselected recommendations.

RESULTS

In the first term, 20 recommendations were preselected (Epidemiology 4, Scores 3, Diagnostic tools 4, Treatment 6 and De-escalation approaches 3). After the second round, the following 12 were validated: (1) Epidemiology (2 recommendations): think about candidiasis in your Intensive Care Unit (ICU) and do not forget that non-Candida albicans-Candida species also exist. (2) Diagnostic tools (4 recommendations): blood cultures should be performed under suspicion every 2-3 days and, if positive, every 3 days until obtaining the first negative result. Obtain sterile fluid and tissue, if possible (direct examination of the sample is important). Use non-culture based methods as microbiological tools, whenever possible. Determination of antifungal susceptibility is mandatory. (3) Scores (1 recommendation): as screening tool, use the Candida Score and determine multicolonization in high risk patients. (4) Treatment (4 recommendations): start early. Choose echinocandins. Withdraw any central venous catheter. Fundoscopy is needed. (5) De-escalation (1 recommendation): only applied when knowing susceptibility determinations and after 3 days of clinical stability. The higher rate of agreement was achieved in the optimization of microbiological tools and the withdrawal of the catheter, whereas the lower rate corresponded to de-escalation therapy and the use of scores.

CONCLUSIONS

The management of invasive candidiasis in ICU patients requires the application of a broad range of knowledge and skills that we summarize in our recommendations. These recommendations may help to identify the potential patients, standardize their global management and improve their outcomes, based on the DELPHI methodology.

Blockade of the negative co-stimulatory molecules PD-1 and CTLA-4 improves survival in primary and secondary fungal sepsis

Introduction

Fungal sepsis is an increasingly common problem in intensive care unit patients.Mortality from fungal sepsis remains high despite antimicrobial therapy that is highly active against most fungal pathogens, a finding consistent with defective host immunity that is present in many patients with disseminated fungemia.One recently recognized immunologic defect that occurs in patients with sepsis is T cell "exhaustion" due to increased expression of programmed cell death -1 (PD-1).This study tested the ability of anti-PD-1 and anti-programmed cell death ligand -1 (anti-PD-L1) antagonistic antibodies to improve survival and reverse sepsis-induced immunosuppression in two mouse models of fungal sepsis.

Methods

Fungal sepsis was induced in mice using two different models of infection, that is, primary fungal sepsis and secondary fungal sepsis occurring after sub-lethal cecal ligation and puncture (CLP).Anti-PD-1 and anti-PD-L1 were administered 24 to 48 h after fungal infection and effects on survival, interferon gamma production, and MHC II expression were examined.

Results

Anti-PD-1 and anti-PD-L1 antibodies were highly effective at improving survival in primary and secondary fungal sepsis.Both antibodies reversed sepsis-induced suppression of interferon gamma and increased expression of MHC II on antigen presenting cells.Blockade of cytotoxic T-lymphocyte antigen-4 (CTLA-4), a second negative co-stimulatory molecule that is up-regulated in sepsis and acts like PD-1 to suppress T cell function, also improved survival in fungal sepsis.

Conclusions

Immuno-adjuvant therapy with anti-PD-1, anti-PD-L1 and anti-CTLA-4 antibodies reverse sepsis-induced immunosuppression and improve survival in fungal sepsis.The present results are consistent with previous studies showing that blockade of PD-1 and CTLA-4 improves survival in bacterial sepsis.Thus, immuno-adjuvant therapy represents a novel approach to sepsis and may have broad applicability in the disorder.Given the relative safety of anti-PD-1 antibody in cancer clinical trials to date, therapy with anti-PD-1 in patients with life-threatening sepsis who have demonstrable immunosuppression should be strongly considered.

Brazilian guidelines for the management of candidiasis - a joint meeting report of three medical societies: Sociedade Brasileira de Infectologia, Sociedade Paulista de Infectologia and Sociedade Brasileira de Medicina Tropical

Candida infections account for 80% of all fungal infections in the hospital environment, including bloodstream, urinary tract and surgical site infections. Bloodstream infections are now a major challenge for tertiary hospitals worldwide due to their high prevalence and mortality rates. The incidence of candidemia in tertiary public hospitals in Brazil is approximately 2.5 cases per 1000 hospital admissions. Due to the importance of this infection, the authors provide a review of the diversity of the genus Candida and its clinical relevance, the therapeutic options and discuss the treatment of major infections caused by Candida. Each topography is discussed with regard to epidemiological, clinical and laboratory diagnostic and therapeutic recommendations based on levels of evidence.

Dectin-1 activation controls maturation of β-1,3-glucan-containing phagosomes

Elimination of fungal pathogens by phagocytes requires phagosome maturation, a process that involves the recruitment and fusion of intracellular proteins. The role of Dectin-1, a β-1,3-glucan receptor, critical for fungal recognition and triggering of Th17 responses, to phagosomal maturation has not been defined. We show that GFP-Dectin-1 translocates to the fungal phagosome, but its signal decays after 2 h. Inhibition of acidification results in retention of GFP-Dectin-1 to phagosome membranes highlighting the requirement for an acidic pH. Following β-1,3-glucan recognition, GFP-Dectin-1 undergoes tyrosine phosphorylation by Src kinases with subsequent Syk activation. Our results demonstrate that Syk is activated independently of intraphagosomal pH. Inhibition of Src or Syk results in prolonged retention of GFP-Dectin-1 to the phagosome signifying a link between Syk and intraphagosomal pH. β-1,3-glucan phagosomes expressing a signaling incompetent Dectin-1 failed to mature as demonstrated by prolonged Dectin-1 retention, presence of Rab5B, failure to acquire LAMP-1 and inability to acidify. Phagosomes containing Candida albicans also require Dectin-1-dependent Syk activation for phagosomal maturation. Taken together, these results support a model where Dectin-1 not only controls internalization of β-1,3-glucan containing cargo and triggers proinflammatory cytokines, but also acts as a master regulator for subsequent phagolysosomal maturation through Syk activation.

Antifungal efficacy during Candida krusei infection in non-conventional models correlates with the yeast in vitro susceptibility profile

The incidence of opportunistic fungal infections has increased in recent decades due to the growing proportion of immunocompromised patients in our society. Candida krusei has been described as a causative agent of disseminated fungal infections in susceptible patients. Although its prevalence remains low among yeast infections (2-5%), its intrinsic resistance to fluconazole makes this yeast important from epidemiologic aspects. Non mammalian organisms are feasible models to study fungal virulence and drug efficacy. In this work we have used the lepidopteran Galleria mellonella and the nematode Caenorhabditis elegans as models to assess antifungal efficacy during infection by C. krusei. This yeast killed G. mellonella at 25, 30 and 37°C and reduced haemocytic density. Infected larvae melanized in a dose-dependent manner. Fluconazole did not protect against C. krusei infection, in contrast to amphotericin B, voriconazole or caspofungin. However, the doses of these antifungals required to obtain larvae protection were always higher during C. krusei infection than during C. albicans infection. Similar results were found in the model host C. elegans. Our work demonstrates that non mammalian models are useful tools to investigate in vivo antifungal efficacy and virulence of C. krusei.

[Double fungemia. Report of four Tunisian cases]

Fungemia is classically caused by a single species and the detection of more than one species in blood samples is uncommon. We report four cases of mixed fungemia (MF) diagnosed in the parasitology-mycology laboratory of Farhat-Hached hospital in Sousse, Tunisia. The MF episodes occurred in two neonates and two adults suffering from acute myeloid leukemia. Two fungal species were detected concomitantly within the same blood culture in all cases. Species combination was detected by the subculture of the blood culture on Candida ID(®) chromogenic medium in three cases and on Sabouraud agar in one case. Predisposing factors were: indwelling catheters (4/4), broad-spectrum antibiotics (3/4), neutropenia (2/4), exclusive parenteral nutrition (2/4) and Candida colonization (1/4). Patients presented febrile sepsis with no response to broad-spectrum antibiotic therapy in all cases. Outcome under antifungal treatment was favorable in two cases and the two other patients died.

CONCLUSION

MF appears similar to the more common monomicrobial fungemia. The use of chromogenic media in routine can improve the detection of MF episodes allowing appropriate antifungal therapy.

Epidemiology of candidemia in Latin America: a laboratory-based survey

Background

The epidemiology of candidemia varies depending on the geographic region. Little is known about the epidemiology of candidemia in Latin America.

Methods

We conducted a 24-month laboratory-based survey of candidemia in 20 centers of seven Latin American countries. Incidence rates were calculated and the epidemiology of candidemia was characterized.

Results

Among 672 episodes of candidemia, 297 (44.2%) occurred in children (23.7% younger than 1 year), 36.2% in adults between 19 and 60 years old and 19.6% in elderly patients. The overall incidence was 1.18 cases per 1,000 admissions, and varied across countries, with the highest incidence in Colombia and the lowest in Chile. Candida albicans (37.6%), C. parapsilosis (26.5%) and C. tropicalis (17.6%) were the leading agents, with great variability in species distribution in the different countries. Most isolates were highly susceptible to fluconazole, voriconazole, amphotericin B and anidulafungin. Fluconazole was the most frequent agent used as primary treatment (65.8%), and the overall 30-day survival was 59.3%.

Conclusions

This first large epidemiologic study of candidemia in Latin America showed a high incidence of candidemia, high percentage of children, typical species distribution, with C. albicans, C. parapsilosis and C. tropicalis accounting for the majority of episodes, and low resistance rates.

Evaluation of PNA-FISH yeast traffic light for rapid identification of yeast directly from positive blood cultures and assessment of clinical impact

The PNA-FISH Yeast Traffic Light assay was performed on 54 clinical isolates of yeasts inoculated into blood culture bottles. The assay showed high sensitivity (Candida albicans/C. parapsilosis, 100%; C. glabrata/C. krusei, 92.3%; C. tropicalis, 100%) and specificity (C. albicans/C. parapsilosis, 100%; C. glabrata/C. krusei, 94.8%; C. tropicalis, 100%). Case note review estimated a change in therapy in 29% of cases had the PNA-FISH result been available to the clinician.

Structural analysis of the active sites of dihydrofolate reductase from two species of Candida uncovers ligand-induced conformational changes shared among species

A novel strategy for targeting the pathogenic organisms Candida albicans and Candida glabrata focuses on the development of potent and selective antifolates effective against dihydrofolate reductase. Crystal structure analysis suggested that an essential loop at the active site (Thr 58-Phe 66) differs from the analogous residues in the human enzyme, potentially providing a mechanism for achieving selectivity. In order to probe the role of this loop, we employed chemical synthesis, crystal structure determination and molecular dynamics simulations. The results of these analyses show that the loop residues undergo ligand-induced conformational changes that are similar among the fungal and human species.

A risk factor analysis of healthcare-associated fungal infections in an intensive care unit: a retrospective cohort study

Background

The incidence of fungal healthcare-associated infection (HAI) has increased in a major teaching hospital in the northern part of Taiwan over the past decade, especially in the intensive care units (ICUs). The purpose of this study was to determine the factors that were responsible for the outbreak and trend in the ICU.

Methods

Surveillance fungal cultures were obtained from “sterile” objects, antiseptic solutions, environment of infected patients and hands of medical personnel. Risk factors for comparison included age, gender, admission service, and total length of stay in the ICU, Acute Physiology and Chronic Health Evaluation (APACHE) II scores at admission to the ICU, main diagnosis on ICU admission, use of invasive devices, receipt of hemodialysis, total parenteral nutrition (TPN) use, history of antibiotic therapy before HAI or during ICU stay in no HAI group, and ICU discharge status (ie, dead or alive). Univariable analysis followed by multiple logistic regression analysis was performed to identify the independent risk factors for ICU fungal HAIs and ICU mortality.

Results

There was a significant trend in ICU fungal HAIs from 1998 to 2009 (P < 0.001). A total of 516 episodes of ICU fungal HAIs were identified; the rates of various infections were urinary tract infection (UTI) (54.8%), blood stream infection (BSI) (30.6%), surgical site infection (SSI) (6.6%), pneumonia (4.5%), other sites (3.5%). The fungi identified were: yeasts (54.8%), Candida albicans (27.3%), Candida tropicalis (6.6%), Candida glabrata (6.6%), Candida parapsilosis (1.9%), Candida species (0.8%), and other fungi (1.9%). Candida albicans accounted for 63% of all Candida species. Yeasts were found in the environment of more heavily infected patients. The independent risk factors (P < 0.05) of developing ICU fungal HAIs from all sites were TPN use, sepsis, surgical patients, mechanical ventilation and an indwelling urinary catheter. The independent risk factors for ICU fungal UTI included TPN use, mechanical ventilation and an indwelling urinary catheter. The independent risk factors for ICU fungal BSI included TPN use, sepsis, and higher APACHE II score. The independent risk factors for ICU fungal pneumonia included TPN use, surgical patients. The independent risk factors for ICU fungal SSI included surgical patients, and TPN use. The odds ratios of TPN use in various infection types ranged from 3.51 to 8.82. The risk of mortality in patients with ICU fungal HAIs was over 2 times that of patients without ICU HAIs in the multiple logistic regression analysis (P < 0.001).

Conclusions

There was a secular trend of an increasing number of fungal HAIs in our ICU over the past decade. Patients with ICU fungal HAIs had a significantly higher mortality rate than did patients without ICU HAIs. Total parenteral nutrition was a significant risk factor for all types of ICU fungal HAIs, and its use should be monitored closely.

The epidemiology of neonatal and pediatric candidemia in England and Wales, 2000-2009

BACKGROUND

There are few population-based studies on the epidemiology of neonatal and pediatric invasive Candida infections, despite their significant clinical impact on patients. This study aimed to describe the epidemiology of pediatric candidemia in England and Wales during a 10-year period as a means of quantifying the changing burden of infection and identifying emerging trends.

METHODS

National Health Service hospital microbiology laboratories in England and Wales routinely report clinically significant invasive infections electronically to the Health Protection Agency. Records of all positive blood cultures for Candida species in children aged <15 years between 2000 and 2009 inclusive were extracted for analysis.

RESULTS

During 2000 to 2009, 1473 childhood candidemia cases were reported in England and Wales (annual incidence, 1.52/100,000 person-years), with the highest rate in <1 year olds (n = 706; 11.0/100,000), followed by 1-4 year olds (n = 440; 1.77/100,000), 5-9 year olds (n = 168; 0.53/100,000) and 10-14 year olds (n = 159; 0.47/100,000). Incidence increased from 1.04 per 100,000 in 2000 to 2.09 per 100,000 in 2007 (P < 0.001) before falling to 1.53 per 100,000 in 2009 (P < 0.001). Candida species was reported in 89.6% (1320/1473) cases, with Candida albicans and Candida parapsilosis accounting for most infections in all age groups. There were no significant differences in species distribution by season or year of study and the proportion of non-albicans cases did not increase with time.

CONCLUSIONS

Pediatric candidemia rates are beginning to fall in England and Wales. C. albicans continues to account for most Candida bloodstream infections in all age groups with no evidence of increases in non-albicans species.

Oral nystatin prophylaxis in surgical/trauma ICU patients: a randomised clinical trial

Introduction

Candida prophylaxis in ICU is still a matter of debate. Oral chemoprophylaxis has been advocated to reduce the incidence of Candida colonisation and infection.

Methods

We performed a randomised trial studying a single drug (nystatin) versus control in surgical/trauma ICU patients. Multiple-site testing for fungi was performed in each patient on ICU admission (T0) and subsequently every 3 days (T3, T6, T9, and so forth). The primary evaluation criterion was the time course of the corrected colonisation index.

Results

Ninety-nine patients were enrolled. At admission, 69 patients exhibited Candida colonisation: the most frequently colonised body sites were the stomach and the pharynx. The most frequent isolated species was Candida albicans. The corrected colonisation index was similar in the two groups at T0 (P = 0.36), while a significant statistical difference was observed between the treatment and control groups at T6 (median 0.14 and 0.33, respectively; P = 0.0016), at T9 (median 0.00 and 0.28, respectively; P = 0.0001), at T12 (median 0.00 and 0.41, respectively; P = 0.0008), and at T15 (median 0.00 and 0.42, respectively; P <0.0003). The same results were obtained in the subgroup of patients already colonised at ICU admission.

Conclusion

This trial shows that nystatin prophylaxis significantly reduces fungal colonisation in surgical/trauma ICU patients, even if already colonised.

Trial registration

ClinicalTrials.gov: NCT01495039

Identification and characterization of the echinocandin B biosynthetic gene cluster from Emericella rugulosa NRRL 11440

Echinocandins are a family of fungal lipidated cyclic hexapeptide natural products. Due to their effectiveness as antifungal agents, three semisynthetic derivatives have been developed and approved for treatment of human invasive candidiasis. All six of the amino acid residues are hydroxylated, including 4R,5R-dihydroxy-L-ornithine, 4R-hydroxyl-L-proline, 3S,4S-dihydroxy-L-homotyrosine, and 3S-hydroxyl-4S-methyl-L-proline. We report here the biosynthetic gene cluster of echinocandin B 1 from Emericella rugulosa NRRL 11440 containing genes encoding for a six-module nonribosomal peptide synthetase EcdA, an acyl-AMP ligase EcdI, and oxygenases EcdG, EcdH, and EcdK. We showed EcdI activates linoleate as linoleyl-AMP and installs it on the first thiolation domain of EcdA. We have also established through ATP-PP(i) exchange assay that EcdA loads L-ornithine in the first module. A separate hty gene cluster encodes four enzymes for de novo generation of L-homotyrosine from acetyl-CoA and 4-hydroxyphenyl-pyruvate is found from the sequenced genome. Deletions in the ecdA, and htyA genes validate their essential roles in echinocandin B production. Five predicted iron-centered oxygenase genes, ecdG, ecdH, ecdK, htyE, and htyF, in the two separate ecd and hty clusters are likely to be the tailoring oxygenases for maturation of the nascent NRPS lipohexapeptidolactam product.

Structural basis for promiscuity and specificity during Candida glabrata invasion of host epithelia

The human pathogenic yeast Candida glabrata harbors more than 20 surface-exposed, epithelial adhesins (Epas) for host cell adhesion. The Epa family recognizes host glycans and discriminates between target tissues by their adhesin (A) domains, but a detailed structural basis for ligand-binding specificity of Epa proteins has been lacking so far. In this study, we provide high-resolution crystal structures of the Epa1A domain in complex with different carbohydrate ligands that reveal how host cell mucin-type O-glycans are recognized and allow a structure-guided classification of the Epa family into specific subtypes. Further detailed structural and functional characterization of subtype-switched Epa1 variants shows that specificity is governed by two inner loops, CBL1 and CBL2, involved in calcium binding as well as by three outer loops, L1, L2, and L3. In summary, our study provides the structural basis for promiscuity and specificity of Epa adhesins, which might further contribute to developing anti-adhesive antimycotics and combating Candida colonization.

Clinical characteristics of candidaemia in adults with haematological malignancy, and antimicrobial susceptibilities of the isolates at a medical centre in Taiwan, 2001-2010

During the period 2001-2010, a total of 154 episodes of candidaemia were noted in 111 of 2574 patients with haematological malignancies at the National Taiwan University Hospital (Taipei, Taiwan). Patients with acute lymphoblastic leukaemia had a significantly higher rate of candidaemia than patients with other haematological malignancies (odds ratio=2.69; P<0.001). Candida tropicalis was the most common Candida species (n=51; 46%), followed by Candida albicans (n=35; 32%), Candida parapsilosis (n=13; 12%), Candida glabrata (n=8; 7%) and Candida krusei (n=4; 4%). Persistent candidaemia was initially identified in 21 patients (18.9%) and was frequently associated with central venous catheter-related infection (52% vs. 24%; P=0.017). Multivariate analysis revealed that shock (P<0.001), allogeneic transplantation (P=0.033) and elderly age (≥60 years) (P=0.041) were independent prognostic factors of 30-day overall survival in patients with haematological malignancy and candidaemia. Minimum inhibitory concentrations (MICs) of a total of 103 non-duplicate blood isolates of Candida spp., including 82 isolates from 82 patients without persistent candidaemia and 21 isolates causing first episodes among 21 patients with persistent candidaemia, to nine antifungal agents were determined using the broth microdilution method. Among the 103 Candida isolates, 53 (51.5%), 94 (91.3%) and 102 (99.0%) were susceptible to itraconazole, fluconazole and voriconazole, respectively. All Candida isolates were susceptible to caspofungin, and 2 (15%) of the 13 C. parapsilosis isolates were not susceptible to micafungin or anidulafungin. The MIC(90) (MIC for 90% of the organisms) of posaconazole was 0.03 mg/L for C. albicans, 0.5 mg/L for C. tropicalis, 0.12 mg/L for C. parapsilosis and 2 mg/L for C. glabrata.

Performance of matrix-assisted laser desorption-time of flight mass spectrometry for identification of clinical yeast isolates

Accurate and fast yeast identification is important when treating patients with invasive fungal disease as susceptibility to antifungal agents is highly species related. Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) provides a powerful tool with a clear potential to improve current diagnostic practice. Two MALDI-TOF-MS-systems (BioTyper/Bruker and Saramis/AXIMA) were evaluated using: (i) A collection of 102 archived, well characterised yeast isolates representing 14 different species and (ii) Prospectively collected isolates obtained from clinical samples at two participating laboratories. Of the 102 archived isolates, 81 (79%) and 92 (90%) were correctly identified by Saramis/AXIMA and BioTyper/Bruker respectively. Saramis/AXIMA was unable to separate Candida albicans, C. africana and C. dubliniensis in 13 of 32 isolates. After manual interpretation of the mass spectra output, all 13 isolates were correctly identified, resulting in an overall identification performance of 92%. No misidentifications occurred with the two systems. Of the routine isolates one laboratory identified 99/99 (100%) and 90/99 (91%) to species level by Saramis/Axima and conventional identification, respectively, whereas the other laboratory identified 83/98 (85%) to species level by both BioTyper/Bruker and conventional identification. Both MALDI-TOF-MS systems are fast, have built-in databases that cover the majority of clinically relevant Candida species, and have an accuracy that outperforms our conventional identification systems.

Microsatellite genotyping clarified conspicuous accumulation of Candida parapsilosis at a cardiothoracic surgery intensive care unit

Candida parapsilosis has become a significant cause of invasive fungal infections in seriously ill patients. Nosocomial outbreaks through direct and indirect contact have been described. The aim of this study was the molecular characterization of what appeared to be an ongoing C. parapsilosis outbreak at the cardiothoracic intensive care unit of the University Hospital of Vienna between January 2007 and December 2008. Using two different molecular typing methods-automated repetitive sequence-based PCR (DiversiLab; bioMérieux) and microsatellite genotyping-we investigated the genetic relationship of 99 C. parapsilosis isolates. Eighty-three isolates originated from the cardiothoracic intensive care unit, while 16 isolates were random control isolates from other intensive care units and a different Austrian hospital. The 99 C. parapsilosis isolates analyzed by repetitive-element PCR all showed identical genotypes, suggesting an ongoing outbreak. In contrast, microsatellite genotyping showed a total of 56 different genotypes. Two major genotypes were observed in 10 and 15 isolates, respectively, whereas another 13 genotypes were observed in 2 to 4 isolates each. Forty-one genotypes were observed only once. Closely related genotypes that differed in only a single microsatellite marker were grouped into clonal complexes. When it comes to C. parapsilosis, microsatellite genotyping is a more discriminative method than repetitive-element PCR genotyping to investigate outbreaks.

In vitro synergism of simvastatin and fluconazole against Candida species

Systemic fungal infections are responsible for high mortality rates. Several species of fungi may be involved, but Candida spp. is the most prevalent. Simvastatin is used to lower cholesterol and also exhibits antifungal action. The aim of this study was to evaluate the synergistic action of simvastatin with fluconazole against strains of Candida spp. Susceptibility testing was performed according to protocol M27-A3, by broth microdilution method and the synergistic effect of simvastatin and fluconazole was calculated based on FICI (Fractional Inhibitory Concentration Index). Eleven strains were evaluated, and simvastatin showed a synergistic effect with fluconazole against 10 (91%) of the Candida spp. strains tested. Simvastatin may be a valuable drug in the treatment of systemic infections caused by Candida spp.

Inactivation of Candida biofilms by non-thermal plasma and its enhancement for fungistatic effect of antifungal drugs

We investigated the antifungal effect of non-thermal plasma, as well as its combination with common antifungal drugs, against Candida biofilms. A direct current atmospheric pressure He/O₂ (2%) plasma microjet (PMJ) was used to treat Candida biofilms in a 96-well plate. Inactivation efficacies of the biofilms were evaluated by XTT assay and counting colony forming units (CFUs). Morphological properties of the biofilms were evaluated by Scanning Electron Microscope (SEM). The sessile minimal inhibitory concentrations (SMICs) of fluconazole, amphotericin B, and caspofungin for the biofilms were also tested. Electron Spin Resonance (ESR) spectroscopy was used to detect the reactive oxygen species (ROS) generated directly and indirectly by PMJ. The Candida biofilms were completely inactivated after 1 min PMJ treatment, where severely deformed fungal elements were observed in SEM images. The SMICs of the tested antifungal drugs for the plasma-treated biofilms were decreased by 2–6 folds of dilution, compared to those of the untreated controls. ROS such as hydroxyl radical (^•OH), superoxide anion radical (^•O₂^-) and singlet molecular oxygen (¹O₂) were detected by ESR. We hence conclude that He/O₂ (2%) plasma alone, as well as in combination with common antifungal drugs, is able to inactivate Candida biofilms rapidly. The generation of ROS is believed to be one of the underlying mechanisms for the fungicidal activity of plasma.

Echinocandin Resistance in Candida Species: Mechanisms of Reduced Susceptibility and Therapeutic Approaches

OBJECTIVE:

To summarize published data regarding mechanisms of reduced echinocandin susceptibility in Candida spp., the impact of echinocandin resistance on the fitness and virulence of Candida isolates, and current and future treatment approaches.

DATA SOURCES:

A search of MEDLINE databases (1966-September 2011) was conducted.

STUDY SELECTION AND DATA EXTRACTION:

Databases were searched using the terms echinocandin, resistance, and Candida. Citations from publications were reviewed for additional references.

DATA SYNTHESIS:

Echinocandins have in vitro activity against most Candida spp. and are first-line agents in the treatment of candidemia. However, case reports describing echinocandin treatment failure due to resistant isolates have been published. Reduced echinocandin susceptibility has been shown to occur via 3 main mechanisms: (1) adaptive stress responses, which result in elevated cell wall chitin content and paradoxical growth in vitro at supra minimum inhibitory concentrations (MICs); (2) acquired FKS mutations, which confer reduced glucan synthase sensitivity, elevated MICs, and are associated with clinical failure; and (3) intrinsic FKS mutations, which are naturally occurring mutations in C. parapsilosis and C. guilliermondii, which confer elevated MIC levels but a lower level of reduced glucan synthase sensitivity compared with acquired FKS mutations. Some FKS mutants have been shown to have significantly reduced fitness and virulence versus wild type isolates and may contribute to the low incidence of echinocandin resistance reported in large surveillance studies. Treatment strategies evaluated for FKS mutants include echinocandin dose escalation and combination with agents such as calcineurin inhibitors, HSP90 inhibitors, and chitin synthase inhibitors.

CONCLUSIONS:

While the incidence of echinocandin resistance in Candida spp. is low, it can present a significant therapeutic challenge, especially in multidrug-resistant Candida isolates. Dose escalation is unlikely to be effective in treating FKS mutant isolates, and significant adverse effects limit the clinical use of agents evaluated as combination therapy. Patients with infections failing to respond to echinocandin therapy should undergo susceptibility testing and be treated with an alternative antifungal agent if possible.

[Epidemiological profile and sensitivity pattern of isolates causing invasive fungal infection vs. colonizing isolates in non-neutropenic critically ill patients]

BACKGROUND

Patients admitted to critical care units can be infected with a large number of fungal isolates that are occasionally responsible for invasive fungal infections (IFI).

AIMS

To describe the epidemiological profile and antifungal susceptibility patterns of fungal isolates in our unit, and to identify key risk factors associated with the development of IFI.

METHODS

A descriptive cohort and retrospective study with patients admitted to a polyvalent Critical Care Unit of a university hospital was carried out. The isolation of at least one fungal species in a culture of biological samples, over a period of 48 months was considered.

RESULTS

Twenty patients out of 232 developed IFI. Patients in the IFI group had a higher mortality and higher Candida score value 48 h prior to clinical diagnosis. Risk factors associated with the development of IFI were chronic obstructive pulmonary disease, gastrointestinal surgery, total parenteral nutrition, and prolonged systemic corticosteroid therapy. The predominant fungal species in both groups was Candida albicans, with global resistance to fluconazole and itraconazole of 1.94%.

CONCLUSIONS

We found a low incidence of species of Candida non-C. albicans in our unit. The rate of resistance to azoles in C. albicans was similar to that of larger series. Gastrointestinal surgery, COPD, prolonged treatment with corticosteroids, and parenteral nutrition administration are risk factors associated with the development of IFI.

Interleukin-7 ameliorates immune dysfunction and improves survival in a 2-hit model of fungal sepsis

BACKGROUND

Secondary hospital-acquired fungal infections are common in critically-ill patients and mortality remains high despite antimicrobial therapy. Interleukin-7 (IL-7) is a potent immunotherapeutic agent that improves host immunity and has shown efficacy in bacterial and viral models of infection. This study examined the ability of IL-7, which is currently in multiple clinical trials (including hepatitis and human immunodeficiency virus), to improve survival in a clinically relevant 2-hit model of fungal sepsis.

METHODS

Mice underwent cecal ligation and puncture to induce peritonitis. Four days later, surviving mice had intravenous injection with Candida albicans. Following Candida infection, mice were treated with IL-7 or saline control. The effect of IL-7 on host immunity and survival was recorded.

RESULTS

IL-7 ameliorated the loss of immune effector cells and increased lymphocyte functions, including activation, proliferation, expression of adhesion molecules, and interferon-γ production. These beneficial effects of IL-7 were associated with an increase in global immunity as reflected by an enhanced delayed type hypersensitivity response and a 1.7-fold improvement in survival.

CONCLUSIONS

The present findings showing that IL-7 improves survival in fungal sepsis, together with its previously reported efficacy in bacterial and viral infectious models, further supports its use as a novel immunotherapeutic in sepsis.