Invasive Candidiasis in Immunocompromised Hospitalized Patients

Surfactants' Interplay with Biofilm Development in Staphylococcus and Candida

The capacity of micro-organisms to form biofilms is a pervasive trait in the microbial realm. For pathogens, biofilm formation serves as a virulence factor facilitating successful host colonization. Simultaneously, infections stemming from biofilm-forming micro-organisms pose significant treatment challenges due to their heightened resistance to antimicrobial agents. Hence, the quest for active compounds capable of impeding microbial biofilm development stands as a pivotal pursuit in biomedical research. This study presents findings concerning the impact of three surfactants, namely, polysorbate 20 (T20), polysorbate 80 (T80), and sodium dodecyl sulfate (SDS), on the initial stage of biofilm development in both Staphylococcus aureus and Candida dubliniensis. In contrast to previous investigations, we conducted a comparative assessment of the biofilm development capacity of these two taxonomically distant groups, predicated on their shared ability to reduce TTC. The common metabolic trait shared by S. aureus and C. dubliniensis in reducing TTC to formazan facilitated a simultaneous evaluation of biofilm development under the influence of surfactants across both groups. Our results revealed that surfactants could impede the development of biofilms in both species by disrupting the initial cell attachment step. The observed effect was contingent upon the concentration and type of compound, with a higher inhibition observed in culture media supplemented with SDS. At maximum concentrations (5%), T20 and T80 significantly curtailed the formation and viability of S. aureus and C. dubliniensis biofilms. Specifically, T20 inhibited biofilm development by 75.36% in S. aureus and 71.18% in C. dubliniensis, while T80 exhibited a slightly lower inhibitory effect, with values ranging between 66.68% (C. dubliniensis) and 65.54% (S. aureus) compared to the controls. Incorporating these two non-toxic surfactants into pharmaceutical formulations could potentially enhance the inhibitory efficacy of selected antimicrobial agents, particularly in external topical applications.

Effects of TiS2 on Inhibiting Candida albicans Biofilm Formation and Its Compatibility with Human Gingival Fibroblasts in Titanium Implants

Titanium is widely used in medical devices, such as dental and orthopedic implants, due to its excellent mechanical properties, low toxicity, and biocompatibility. However, the titanium surface has the risk of microbial biofilm formation, which results in infections from species such as Candida albicans (C. albicans). This kind of biofilm prevents antifungal therapy and complicates the treatment of infectious diseases associated with implanted devices. It is critical to developing a feasible surface to decrease microbial growth while not interfering with the growth of the host cells. This study reports the influence of titanium surface modification to titanium disulfide (TiS₂) on inhibiting C. albicans biofilm formation while allowing the attachment of human gingival fibroblasts (HGFs) on their surface. The surface of titanium parts is directly converted to structured titanium and TiS₂ using direct laser processing and crystal growth methods. C. albicans adhesion and colonization are then investigated on these surfaces by the colony counting assay and reactive oxygen species (ROS) assay, using 2',7'-dichlorofluorescin diacetate (DCFH-DA) and microscopy images. Also, the viability and adhesion of HGFs on these surfaces are investigated to show their adhesion and biocompatibility. Titanium samples with the TiS₂ surface show both C. albicans biofilm inhibition and HGF attachment. This study provides insight into designing and manufacturing titanium biomedical implants.

Candida albicans Reactive Oxygen Species (ROS)-Dependent Lethality and ROS-Independent Hyphal and Biofilm Inhibition by Eugenol and Citral

Candida albicans is part of the normal human flora but is most frequently isolated as the causative opportunistic pathogen of candidiasis. Plant-based essential oils and their components have been extensively studied as antimicrobials, but their antimicrobial impacts are poorly understood. Phenylpropenoids and monoterpenes, for example, eugenol from clove and citral from lemon grass, are potent antifungals against a wide range of pathogens. We report the cellular response of C. albicans to eugenol and citral, alone and combined, using biochemical and microscopic assays. The MICs of eugenol and citral were 1,000 and 256 μg/mL, respectively, with the two exhibiting additive effects based on a fractional inhibitory concentration index of 0.83 ± 0.14. High concentrations of eugenol caused membrane damage, oxidative stress, vacuole segregation, microtubule dysfunction and cell cycle arrest at the G₁/S phase, and while citral had similar impacts, they were reactive oxygen species (ROS) independent. At sublethal concentrations (1/2 to 1/4 MIC), both oils disrupted microtubules and hyphal and biofilm formation in an ROS-independent manner. While both compounds disrupt the cell membrane, eugenol had a greater impact on membrane dysfunction. This study shows that eugenol and citral can induce vacuole and microtubule dysfunction, along with the inhibition of hyphal and biofilm formation. IMPORTANCE Candida albicans is a normal resident on and in the human body that can cause relatively benign infections. However, when our immune system is severely compromised (e.g., cancer chemotherapy patients) or underdeveloped (e.g., newborns), this fungus can become a deadly pathogen, infecting the bloodstream and organs. Since there are only a few effective antifungal agents that can be used to combat fungal infections, these fungi have been exposed to them over and over again, allowing the fungi to develop resistance. Instead of developing antifungal agents that kill the fungi, some of which have undesirable side effects on the human host, researchers have proposed to target the fungal traits that make the fungus more virulent. Here, we show how two components of plant-based essential oils, eugenol and citral, are effective inhibitors of C. albicans virulence traits.

Anaerobic conditions are a major influence on Candida albicans chlamydospore formation

Candidiasis now represents the fourth most frequent nosocomial infection both in the USA and worldwide. Candida albicans is an increasingly common threat to human health as a consequence of AIDS, steroid therapy, organ and tissue transplantation, cancer therapy, broad-spectrum antibiotics, and other immune defects. Unfortunately, these infections carry unacceptably high morbidity, mortality rates and important economic repercussions (estimated total direct cost of approximately 2 billion dollars in 1998 in US hospitals alone). This pathogen can grow both in yeast and filamentous forms and the pathogenic potential of C. albicans is intimately related to certain key processes including filamentation. Chlamydospores are considered to be a dormant form of C. albicans that remain understudied. Chlamydospores have been widely used as a diagnostic tool to separate C. albicans and C. dubliniensis from other Candida species. More recently, media have been developed that use chlamydopsore formation to separate C. albicans and C. dubliniensis from each other. Chlamydospore formation can be stimulated by hypoxic conditions but only on limited specific media types. Here, we show that anaerobic conditions are enough to drive chlamydospore formation in C. albicans on the surface of nutrient-rich agar.

Anti-Candida Activity of Extracts Containing Ellagitannins, Triterpenes and Flavonoids of Terminalia brownii, a Medicinal Plant Growing in Semi-Arid and Savannah Woodland in Sudan

Various parts of Terminalia brownii (Fresen) are used in Sudanese traditional medicine against fungal infections. The present study aimed to verify these uses by investigating the anti-Candida activity and phytochemistry of T. brownii extracts. Established agar diffusion and microplate dilution methods were used for the antifungal screenings. HPLC-DAD and UHPLC/QTOF-MS were used for the chemical fingerprinting of extracts and for determination of molecular masses. Large inhibition zones and MIC values of 312 µg/mL were obtained with acetone, ethyl acetate and methanol extracts of the leaves and acetone and methanol extracts of the roots. In addition, decoctions and macerations of the leaves and stem bark showed good activity. Sixty compounds were identified from a leaf ethyl acetate extract, showing good antifungal activity. Di-, tri- and tetra-gallotannins, chebulinic acid (eutannin) and ellagitannins, including an isomer of methyl-(S)-flavogallonate, terflavin B and corilagin, were detected in T. brownii leaves for the first time. In addition, genipin, luteolin-7-O-glucoside, apigenin, kaempferol-4’-sulfate, myricetin-3-rhamnoside and sericic acid were also characterized. Amongst the pure compounds present in T. brownii leaves, apigenin and β-sitosterol gave the strongest growth inhibitory effects. From this study, it was evident that the leaf extracts of T. brownii have considerable anti-Candida activity with MIC values ranging from 312 to 2500 µg/mL.

The Role of the Oral Immune System in Oropharyngeal Candidiasis-Facilitated Invasion and Dissemination of Staphylococcus aureus

Candida albicans and Staphylococcus aureus account for most invasive fungal and bacterial bloodstream infections (BSIs), respectively. However, the initial point of invasion responsible for S. aureus BSIs is often unclear. Recently, C. albicans has been proposed to mediate S. aureus invasion of immunocompromised hosts during co-colonization of oral mucosal surfaces. The status of the oral immune system crucially contributes to this process in two distinct ways: firstly, by allowing invasive C. albicans growth during dysfunction of extra-epithelial immunity, and secondly following invasion by some remaining function of intra-epithelial immunity. Immunocompromised individuals at risk of developing invasive oral C. albicans infections could, therefore, also be at risk of contracting concordant S. aureus BSIs. Considering the crucial contribution of both oral immune function and dysfunction, the aim of this review is to provide an overview of relevant aspects of intra and extra-epithelial oral immunity and discuss predominant immune deficiencies expected to facilitate C. albicans induced S. aureus BSIs.

DectiSomes: Glycan Targeting of Liposomal Drugs Improves the Treatment of Disseminated Candidiasis

Candida albicans causes life-threatening disseminated candidiasis. Individuals at greatest risk have weakened immune systems. An outer cell wall, exopolysaccharide matrix, and biofilm rich in oligoglucans and oligomannans help Candida spp. evade host defenses. Even after antifungal treatment, the 1-year mortality rate exceeds 25%. Undoubtedly, there is room to improve drug performance. The mammalian C-type lectin pathogen receptors Dectin-1 and Dectin-2 bind to fungal oligoglucans and oligomannans, respectively. We previously coated amphotericin B-loaded liposomes, AmB-LLs, pegylated analogs of AmBisome, with the ligand binding domains of these two Dectins. DectiSomes, DEC1-AmB-LLs and DEC2-AmB-LLs, showed two distinct patterns of binding to the exopolysaccharide matrix surrounding C. albicans hyphae grown in vitro. Here we showed that DectiSomes were preferentially associated with fungal colonies in the kidneys. In a neutropenic mouse model of candidiasis, DEC1-AmB-LLs and DEC2-AmB-LLs delivering only one dose of 0.2 mg/kg AmB reduced the kidney fungal burden several fold relative to AmB-LLs. DEC1-AmB-LLs and DEC2-AmB-LLs increased the percent of surviving mice 2.5-fold and 8.3-fold, respectively, relative to AmB-LLs. Dectin-2 targeting of anidulafungin loaded liposomes, DEC2-AFG-LLs, and of commercial AmBisome, DEC2-AmBisome, reduced fungal burden in the kidneys several fold over their untargeted counterparts. The data herein suggest that targeting of a variety of antifungal drugs to fungal glycans may achieve lower safer effective doses and improve drug efficacy against a variety of invasive fungal infections.

Structural Insights into the Azole Resistance of the Candida albicans Darlington Strain Using Saccharomyces cerevisiae Lanosterol 14α-Demethylase as a Surrogate

Target-based azole resistance in Candida albicans involves overexpression of the ERG11 gene encoding lanosterol 14α-demethylase (LDM), and/or the presence of single or multiple mutations in this enzyme. Overexpression of Candida albicans LDM (CaLDM) Y132H I471T by the Darlington strain strongly increased resistance to the short-tailed azoles fluconazole and voriconazole, and weakly increased resistance to the longer-tailed azoles VT-1161, itraconazole and posaconazole. We have used, as surrogates, structurally aligned mutations in recombinant hexahistidine-tagged full-length Saccharomyces cerevisiae LDM6×His (ScLDM6×His) to elucidate how differential susceptibility to azole drugs is conferred by LDM of the C. albicans Darlington strain. The mutations Y140H and I471T were introduced, either alone or in combination, into ScLDM6×His via overexpression of the recombinant enzyme from the PDR5 locus of an azole hypersensitive strain of S. cerevisiae. Phenotypes and high-resolution X-ray crystal structures were determined for the surrogate enzymes in complex with representative short-tailed (voriconazole) and long-tailed (itraconazole) triazoles. The preferential high-level resistance to short-tailed azoles conferred by the ScLDM Y140H I471T mutant required both mutations, despite the I471T mutation conferring only a slight increase in resistance. Crystal structures did not detect changes in the position/tilt of the heme co-factor of wild-type ScLDM, I471T and Y140H single mutants, or the Y140H I471T double-mutant. The mutant threonine sidechain in the Darlington strain CaLDM perturbs the environment of the neighboring C-helix, affects the electronic environment of the heme, and may, via differences in closure of the neck of the substrate entry channel, increase preferential competition between lanosterol and short-tailed azole drugs.

Anti-Infective Antibody-Derived Peptides Active against Endogenous and Exogenous Fungi

Mycoses still represent relevant opportunistic infections worldwide, although overshadowed in recent years by other severe and more widespread infections. Moreover, deep-seated mycoses are often accompanied by unacceptably high mortality rates. Etiologic agents include endogenous components of the mycobiota, Candida and Malassezia species above all, and exogenous species, both yeasts and filamentous fungi. Old and new fungal pathogens are increasingly characterized by resistance to the existing antifungal agents, making imperative the search for effective and safe new therapeutics. Among the candidate molecules proposed in recent decades, synthetic peptides derived from the complementarity determining and constant regions of diverse antibodies (Abs), as well as the translated products of Ab-encoding genes, have proved of considerable interest. Their anti-infective activities, regardless of the specificity and isotype of the originating Ab, will be briefly presented and discussed in the light of their different mechanisms of action. Intriguing suggestions on the possible function of Abs after their half-life will be presented, following the recent detection, in human serum, of an antimicrobial Ab-derived peptide. Overall, Abs could represent a source of biologically active, highly flexible peptides, devoid of detectable toxicity, which can be easily synthesized and manipulated to be used, alone or in association with already available drugs, for new anti-infective strategies.

Antagonistic effect of isolated and commercially available probiotics on the growth of Candida albicans on acrylic resin denture surfaces

STATEMENT OF PROBLEM

Biofilms can be retained on dental prostheses leading to the development of infections. The indiscriminate use of antifungal drugs can result in the development of microorganisms that are resistant to these antimicrobial agents. Whether probiotics are a suitable alternative for reducing the prevalence of oral candidiasis is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of 6 different live strains of probiotics and 2 commercially available probiotic supplements used for inhibiting the growth of Candida albicans biofilm in heat-polymerized acrylic resin denture base material and to determine whether biofilm byproducts modify the surface of specimens.

MATERIAL AND METHODS

Biofilms of C. albicans were formed on acrylic resin specimens in the presence of probiotics and quantified by colony-forming units (CFUs), and the surface roughness (Ra) of the specimens was assessed before and after the formation of biofilms. The CFU and roughness data were analyzed by analysis of variance and the Tukey HSD test (α=.05).

RESULTS

A significant decrease in the number (CFU/mL) of C. albicans cells was found when they were cultured with 4 probiotics: B. lactis (P=.045), B. longum (P<.001), L. casei (P<.001), and L. helveticus (P<.001) and with the commercially available probiotic Prolive (P=.05). The Ra of specimens decreased after exposure to different microbial biofilms (P≤.05) except in 3 experimental groups.

CONCLUSIONS

In general, the tested probiotics had an antagonistic effect on the growth of C. albicans, and the surface of acrylic resin was altered after exposure to biofilm byproducts.

In vitro Candida albicans biofilm formation on different titanium surface topographies

Objectives

To investigate if differences in titanium implant surface topography influence Candida albicans biofilm formation.

Materials and Methods

Titanium discs were prepared and characterized using a profilometer: Group A (R_a 0.15 µm, smooth), Group B (R_a 0.64 µm, minimally rough) and Group C (R_a 1.3 µm, moderately rough). Contact angle and surface free energy (SFE) were determined for each group. Non-preconditioned titanium discs were incubated with C. albicans for 24 h. In additional experiments, the titanium discs were initially coated with human saliva, bovine serum albumin or phosphate-buffered saline for 2 h before incubation with C. albicans for 24 h. The amount of fungal biofilm formation was quantified using a colorimetric assay.

Results

C. albicans biofilm formation was significantly lower (p < 0.05) on the minimally rough titanium surface compared to smooth and moderately rough surfaces. The titanium surface displaying the lowest SFE (Group B) was associated with significantly lower (p < 0.05) C. albicans biofilm formation than the other two groups. Salivary coating resulted in greater adherence of C. albicans with increased surface roughness.

Conclusions

The minimally rough titanium discs displayed lowest SFE compared to smooth and moderately rough surfaces and showed the least C. albicans biofilm formation. This study demonstrated that C. albicans biofilm formation increased in a SFE-dependent manner. These findings suggest that SFE might be a more explanatory factor for C. albicans biofilm formation on titanium surfaces than roughness. The presence of a pellicle coating may negate the impact of SFE on C. albicans biofilm formation on titanium surfaces.

In Vitro Activity of Carbosilane Cationic Dendritic Molecules on Prevention and Treatment of Candida Albicans Biofilms

Candida spp. are one of the most common fungal pathogens. Biofilms formed by Candidaalbicans offer resistance mechanisms against most antifungal agents. Therefore, development of new molecules effective against these microorganisms, alone or in combination with antifungal drugs, is extremely necessary. In the present work, we carried out a screening process of different cationic carbosilane dendritic molecules against C. albicans. In vitro activity against biofilm formation and biofilms was tested in both Colección Española de Cultivos Tipo (CECT) 1002 and clinical C. albicans strains. Cytotoxicity was studied in human cell lines, and biofilm alterations were observed by scanning electron microscopy (SEM). Antifungal activity of the carbosilane dendritic molecules was assessed by monitoring cell viability using both established and novel cell viability assays. One out of 14 dendritic molecules tested, named BDSQ024, showed the highest activity with a minimum biofilm inhibitory concentration (MBIC) for biofilm formation and a minimum biofilm damaging concentration (MBDC) for existing biofilm of 16–32 and 16 mg/L, respectively. Synergy with amphotericin (AmB) and caspofungin (CSF) at non-cytotoxic concentrations was found. Therefore, dendritic compounds are exciting new antifungals effective at preventing Candida biofilm formation and represent a potential novel therapeutic agent for treatment of C. albicans infection in combination with existing clinical antifungals.

Preparation and In Vitro Evaluation of Alginate Microparticles Containing Amphotericin B for the Treatment of Candida Infections

Invasive candidiasis (IC) remains as a major cause of morbidity and mortality in critically ill patients. Amphotericin B (AmB) is one of the most effective antifungal agents commonly used to treat this infection. However, it induces severe side effects such as nephrotoxicity, cardiac alterations, nausea, fever, and liver damage. The utilization of drug delivery systems has been explored to overcome these limitations. Several AmB lipid formulations have been developed and are currently available in the market. Although they have the ability to reduce the main side effects of free AmB, their high cost, necessity of repeated intravenous injections for successful treatment, and incidence of pulmonary toxicity have limited their use. In the last decades, alginate has gained significant interest in drug delivery applications as a cost-effective strategy to improve the safety and therapeutic effect of toxic drugs. In this work, the clinically relevant drug AmB was encapsulated into alginate microparticles using the emulsification/external gelation method. We hypothesize that this synthesis strategy may positively impact the antifungal efficacy of AmB-loaded MCPs toward Candida albicans cells while reducing the toxicity in human lung cells. To prove this hypothesis, the ability of the microplatform to disrupt the cellular membrane potential was tested and its antifungal effectiveness toward Candida albicans cells was evaluated using the cell counting and plate count methods. Moreover, the toxicity of the microplatform in human lung cells was evaluated using CellTiter 96® AQueous cell viability assay and qualitative diffusion analysis of acridine orange. Our results demonstrated that the platform developed in this work was able to induce antifungal toxicity against Candida albicans yeast cells at the same level of free AmB with minimal toxicity to lung cells, which is one of the main side effects induced by commercial drug delivery systems containing AmB. Overall, our data provides convincing evidence about the effectiveness of the alginate-based microplatform toward Candida albicans cells. In addition, this vehicle may not require several infusions for a successful treatment while reducing the pulmonary toxic effect induced by commercial lipid formulations.

Small-Molecule Inhibitors Targeting Sterol 14α-Demethylase (CYP51): Synthesis, Molecular Modelling and Evaluation Against Candida albicans

Fungal infections are a global issue affecting over 150 million people worldwide annually, with 750 000 of these caused by invasive Candida infections. Azole drugs are the frontline treatment against fungal infections; however, resistance to current azole antifungals in C. albicans poses a threat to public health. Two series of novel azole derivatives, short and extended derivatives, have been designed, synthesised and investigated for CYP51 inhibitory activity, binding affinity and minimum inhibitory concentration (MIC) against C. albicans strains. The short derivatives were more potent against the C. albicans strains (e. g., MIC 2‐(4‐chlorophenyl)‐N‐(2,4‐dichlorobenzyl)‐3‐(1H‐imidazol‐1‐yl)propanamide (5 f) <0.03 μg/mL, N‐(4‐((4‐chlorophenyl)sulfonamido)benzyl)‐2‐phenyl‐3‐(1H‐1,2,4‐triazol‐1‐yl)propanamide (12 c), 1 μg/mL, fluconazole 0.125 μg/mL) but both displayed comparable enzyme binding and inhibition (5 fK_d 62±17 nM, IC₅₀ 0.46 μM; 12 cK_d 43±18 nM, IC₅₀ 0.33 μM, fluconazole K_d 41±13 nM, IC₅₀ 0.31 μM, posaconazole K_d 43±11 nM, IC₅₀ 0.2 μM). The short series had poor selectivity for CaCYP51 over the human homologue, whereas the selectivity of the extended series, for example, compound 12 c, was higher (21.5‐fold) than posaconazole (4.7‐fold) based on K_d values, although posaconazole was more selective (615‐fold) than 12 c (461‐fold) based on IC₅₀ values. Based on inhibitory activity and selectivity profile, the extended series are the better of the two series for further development.

Identification of Candida Species from Clinical Samples in a Honduran Tertiary Hospital

Candida species are one of the most important causes of human infections, especially in hospitals and among immunocompromised patients. The correct and rapid etiological identification of yeast infections is important to provide adequate therapy, reduce mortality, and control outbreaks. In this study, Candida species were identified in patients with suspected fungal infection, and phenotypic and genotypic identification methods were compared. A total of 167 axenic fungal cultures and 46 clinical samples were analyzed by HardyCHROM^®, MicroScan^®(Omron Microscan Systems Inc, Renton, WA, USA), and PCR-RFLP (Restriction Fragment Length Polymorphisms). The species of the C. albicans complex were the most frequent, followed by C. tropicalis and C. glabrata. Less common but clinically relevant species of Candida were also isolated. The comparison between the three methods was concordant, especially for the most common Candida species. Fungal DNA amplification was successful in all clinical samples.

Population-Based Active Surveillance for Culture-Confirmed Candidemia - Four Sites, United States, 2012-2016

PROBLEM/CONDITION

Candidemia is a bloodstream infection (BSI) caused by yeasts in the genus Candida. Candidemia is one of the most common health care-associated BSIs in the United States, with all-cause in-hospital mortality of up to 30%.

PERIOD COVERED

2012-2016.

DESCRIPTION OF SYSTEM

CDC's Emerging Infections Program (EIP), a collaboration among CDC, state health departments, and academic partners that was established in 1995, was used to conduct active, population-based laboratory surveillance for candidemia in 22 counties in four states (Georgia, Maryland, Oregon, and Tennessee) with a combined population of approximately 8 million persons. Laboratories serving the catchment areas were recruited to report candidemia cases to the local EIP program staff. A case was defined as a blood culture that was positive for a Candida species collected from a surveillance area resident during 2012-2016. Isolates were sent to CDC for species confirmation and antifungal susceptibility testing. Any subsequent blood cultures with Candida within 30 days of the initial positive culture in the same patient were considered part of the same case. Trained surveillance officers collected clinical information from the medical chart for all cases, and isolates were sent to CDC for species confirmation and antifungal susceptibility testing.

RESULTS

Across all sites and surveillance years (2012-2016), 3,492 cases of candidemia were identified. The crude candidemia incidence averaged across sites and years during 2012-2016 was 8.7 per 100,000 population; important differences in incidence were found by site, age group, sex, and race. The crude annual incidence was the highest in Maryland (14.1 per 100,000 population) and lowest in Oregon (4.0 per 100,000 population). The crude annual incidence of candidemia was highest among adults aged ≥65 years (25.5 per 100,000 population) followed by infants aged <1 year (15.8). The crude annual incidence was higher among males (9.4) than among females (8.0) and was approximately 2 times greater among blacks than among nonblacks (13.7 versus 5.8). Ninety-six percent of cases occurred in patients who were hospitalized at the time of or during the week after having a positive culture. One third of cases occurred in patients who had undergone a surgical procedure in the 90 days before the candidemia diagnosis, 77% occurred in patients who had received systemic antibiotics in the 14 days before the diagnosis, and 73% occurred in patients who had had a central venous catheter (CVC) in place within 2 days before the diagnosis. Ten percent were in patients who had used injection drugs in the past 12 months. The median time from admission to candidemia diagnosis was 5 days (interquartile range [IQR]: 0-16 days). Among 2,662 cases that were treated in adults aged >18 years, 34% were treated with fluconazole alone, 30% with echinocandins alone, and 34% with both. The all-cause, in-hospital case-fatality ratio was 25% for any time after admission; the all-cause in-hospital case-fatality ratio was 8% for <48 hours after a positive culture for Candida species. Candida albicans accounted for 39% of cases, followed by Candida glabrata (28%) and Candida parapsilosis (15%). Overall, 7% of isolates were resistant to fluconazole and 1.6% were resistant to echinocandins, with no clear trends in resistance over the 5-year surveillance period.

INTERPRETATION

Approximately nine out of 100,000 persons developed culture-positive candidemia annually in four U.S. sites. The youngest and oldest persons, men, and blacks had the highest incidences of candidemia. Patients with candidemia identified in the surveillance program had many of the typical risk factors for candidemia, including recent surgery, exposure to broad-spectrum antibiotics, and presence of a CVC. However, an unexpectedly high proportion of candidemia cases (10%) occurred in patients with a history of injection drug use (IDU), suggesting that IDU has become a common risk factor for candidemia. Deaths associated with candidemia remain high, with one in four cases resulting in death during hospitalization.

PUBLIC HEALTH ACTION

Active surveillance for candidemia yielded important information about the disease incidence and death rate and persons at greatest risk. The surveillance was expanded to nine sites in 2017, which will improve understanding of the geographic variability in candidemia incidence and associated clinical and demographic features. This surveillance will help monitor incidence trends, track emergence of resistance and species distribution, monitor changes in underlying conditions and predisposing factors, assess trends in antifungal treatment and outcomes, and be helpful for those developing prevention efforts. IDU has emerged as an important risk factor for candidemia, and interventions to prevent invasive fungal infections in this population are needed. Surveillance data documenting that approximately two thirds of candidemia cases were caused by species other than C. albicans, which are generally associated with greater antifungal resistance than C. albicans, and the presence of substantial fluconazole resistance supports 2016 clinical guidelines recommending a switch from fluconazole to echinocandins as the initial treatment for candidemia in most patients.

Direct Detection of Candida albicans with a Membrane Based Electrochemical Impedance Spectroscopy Sensor

Candidemia and invasive candidiasis is a cause of high mortality and morbidity rates among hospitalized patients worldwide. The occurrence of the infections increases due to the complexity of the patients and overuse of the antifungal therapy. The current Candida detection method includes blood culturing which is a lengthy procedure and thus delays the administration of the antifungal therapy. Even though the results are available after 48 h it is still the gold standard in pathogen detection in a hospital setting. In this work we present an electrochemical impedance sensor that is capable of detecting Candida albicans yeast. The yeast cells are captured on electrodes specifically functionalized with anti-Candida antibodies and detection is achieved by electrochemical impedance spectroscopy. The sensor allows for detection of the yeast cells at clinically relevant concentrations in less than 1 h.

Host-Pathogen Interactions Mediated by MDR Transporters in Fungi: As Pleiotropic as it Gets!

Fungal infections caused by Candida, Aspergillus, and Cryptococcus species are an increasing problem worldwide, associated with very high mortality rates. The successful prevalence of these human pathogens is due to their ability to thrive in stressful host niche colonization sites, to tolerate host immune system-induced stress, and to resist antifungal drugs. This review focuses on the key role played by multidrug resistance (MDR) transporters, belonging to the ATP-binding cassette (ABC), and the major facilitator superfamilies (MFS), in mediating fungal resistance to pathogenesis-related stresses. These clearly include the extrusion of antifungal drugs, with C. albicans CDR1 and MDR1 genes, and corresponding homologs in other fungal pathogens, playing a key role in this phenomenon. More recently, however, clues on the transcriptional regulation and physiological roles of MDR transporters, including the transport of lipids, ions, and small metabolites, have emerged, linking these transporters to important pathogenesis features, such as resistance to host niche environments, biofilm formation, immune system evasion, and virulence. The wider view of the activity of MDR transporters provided in this review highlights their relevance beyond drug resistance and the need to develop therapeutic strategies that successfully face the challenges posed by the pleiotropic nature of these transporters.

Candida Biofilms: Threats, Challenges, and Promising Strategies

Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis, highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS) and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed.

Six Key Traits of Fungi: Their Evolutionary Origins and Genetic Bases

The fungal lineage is one of the three large eukaryotic lineages that dominate terrestrial ecosystems. They share a common ancestor with animals in the eukaryotic supergroup Opisthokonta and have a deeper common ancestry with plants, yet several phenotypes, such as morphological, physiological, or nutritional traits, make them unique among all living organisms. This article provides an overview of some of the most important fungal traits, how they evolve, and what major genes and gene families contribute to their development. The traits highlighted here represent just a sample of the characteristics that have evolved in fungi, including polarized multicellular growth, fruiting body development, dimorphism, secondary metabolism, wood decay, and mycorrhizae. However, a great number of other important traits also underlie the evolution of the taxonomically and phenotypically hyperdiverse fungal kingdom, which could fill up a volume on its own. After reviewing the evolution of these six well-studied traits in fungi, we discuss how the recurrent evolution of phenotypic similarity, that is, convergent evolution in the broad sense, has shaped their phylogenetic distribution in extant species.

Transcriptional Control of Drug Resistance, Virulence and Immune System Evasion in Pathogenic Fungi: A Cross-Species Comparison

Transcription factors are key players in the control of the activation or repression of gene expression programs in response to environmental stimuli. The study of regulatory networks taking place in fungal pathogens is a promising research topic that can help in the fight against these pathogens by targeting specific fungal pathways as a whole, instead of targeting more specific effectors of virulence or drug resistance. This review is focused on the analysis of regulatory networks playing a central role in the referred mechanisms in the human fungal pathogens Aspergillus fumigatus, Cryptococcus neoformans, Candida albicans, Candida glabrata, Candida parapsilosis, and Candida tropicalis. Current knowledge on the activity of the transcription factors characterized in each of these pathogenic fungal species will be addressed. Particular focus is given to their mechanisms of activation, regulatory targets and phenotypic outcome. The review further provides an evaluation on the conservation of transcriptional circuits among different fungal pathogens, highlighting the pathways that translate common or divergent traits among these species in what concerns their drug resistance, virulence and host immune evasion features. It becomes evident that the regulation of transcriptional networks is complex and presents significant variations among different fungal pathogens. Only the oxidative stress regulators Yap1 and Skn7 are conserved among all studied species; while some transcription factors, involved in nutrient homeostasis, pH adaptation, drug resistance and morphological switching are present in several, though not all species. Interestingly, in some cases not very homologous transcription factors display orthologous functions, whereas some homologous proteins have diverged in terms of their function in different species. A few cases of species specific transcription factors are also observed.

Diagnosis of Invasive Fungal Diseases in Hematological Malignancies: A Critical Review of Evidence and Turkish Expert Opinion (TEO-2)

One of the most problematic issues in hematological malignancies is the diagnosis of invasive fungal diseases. Especially, the difficulty of mycological diagnosis and the necessity of immediate intervention in molds have led to the adoption of “surrogate markers” that do not verify but rather strongly suggest fungal infection. The markers commonly used are galactomannan (GM), beta-glucan, and imaging methods. Although there are numerous studies on these diagnostic approaches, none of these markers serve as a support for the clinician, as is the case in human immunodeficiency virus (HIV) or cytomegalovirus (CMV) infections. This paper has been prepared to explain the diagnostic tests. As molecular tests have not been standardized and are not used routinely in the clinics, they will not be mentioned here.

Gold Nanoparticle-Photosensitizer Conjugate Based Photodynamic Inactivation of Biofilm Producing Cells: Potential for Treatment of C. albicans Infection in BALB/c Mice

Background

Photodynamic therapy (PDT) has been found to be effective in inhibiting biofilm producing organisms. We investigated the photodynamic effect of gold nanoparticle (GNP) conjugated photosensitizers against Candida albicans biofilm. We also examined the photodynamic efficacy of photosensitizer (PS) conjugated GNPs (GNP-PS) to treat skin and oral C. albicans infection in BALB/c mice.

Methods

The biomimetically synthesized GNPs were conjugated to photosensitizers viz. methylene blue (MB) or toluidine blue O (TB). The conjugation of PSs with GNPs was characterized by spectroscopic and microscopic techniques. The efficacy of gold nanoparticle conjugates against C. albicans biofilm was demonstrated by XTT assay and microscopic studies. The therapeutic efficacy of the combination of the GNP conjugates against cutaneous C. albicans infection was examined in mouse model by enumerating residual fungal burden and histopathological studies.

Results

The GNP-PS conjugate based PDT was found to effectively kill both C. albicans planktonic cells and biofilm populating hyphal forms. The mixture of GNPs conjugated to two different PSs significantly depleted the hyphal C. albicans burden against superficial skin and oral C. albicans infection in mice.

Conclusion

The GNP-PS conjugate combination exhibits synergism in photodynamic inactivation of C. albicans. The GNP conjugate based PDT can be employed effectively in treatment of cutaneous C. albicans infections in model animals. The antibiofilm potential of PDT therapy can also be exploited in depletion of C. albicans on medical appliances such as implants and catheters etc.

Silver nanoparticles in dental biomaterials

Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time.

Novel strategies to fight Candida species infection

In recent years, there has been a significant increase in the incidence of human fungal infections. The increase in cases of infection caused by Candida species, and the consequent excessive use of antimicrobials, has favored the emergence of resistance to conventional antifungal agents over the past decades. Consequently, Candida infections morbidity and mortality are also increasing. Therefore, new approaches are needed to improve the outcome of patients suffering from Candida infections, because it seems unlikely that the established standard treatments will drastically lower the morbidity of mucocutaneous Candida infections and the high mortality associated with invasive candidiasis. This review aims to present the last advances in the traditional antifungal therapy, and present an overview of novel strategies that are being explored for the treatment of Candida infections, with a special focus on combined antifungal agents, antifungal therapies with alternative compounds (plant extracts and essential oils), adjuvant immunotherapy, photodynamic therapy and laser therapy.

The clinical candidate VT-1161 is a highly potent inhibitor of Candida albicans CYP51 but fails to bind the human enzyme

The binding and cytochrome P45051 (CYP51) inhibition properties of a novel antifungal compound, VT-1161, against purified recombinant Candida albicans CYP51 (ERG11) and Homo sapiens CYP51 were compared with those of clotrimazole, fluconazole, itraconazole, and voriconazole. VT-1161 produced a type II binding spectrum with Candida albicans CYP51, characteristic of heme iron coordination. The binding affinity of VT-1161 for Candida albicans CYP51 was high (dissociation constant [Kd], ≤ 39 nM) and similar to that of the pharmaceutical azole antifungals (Kd, ≤ 50 nM). In stark contrast, VT-1161 at concentrations up to 86 μM did not perturb the spectrum of recombinant human CYP51, whereas all the pharmaceutical azoles bound to human CYP51. In reconstitution assays, VT-1161 inhibited Candida albicans CYP51 activity in a tight-binding fashion with a potency similar to that of the pharmaceutical azoles but failed to inhibit the human enzyme at the highest concentration tested (50 μM). In addition, VT-1161 (MIC = 0.002 μg ml(-1)) had a more pronounced fungal sterol disruption profile (increased levels of methylated sterols and decreased levels of ergosterol) than the known CYP51 inhibitor voriconazole (MIC = 0.004 μg ml(-1)). Furthermore, VT-1161 weakly inhibited human CYP2C9, CYP2C19, and CYP3A4, suggesting a low drug-drug interaction potential. In summary, VT-1161 potently inhibited Candida albicans CYP51 and culture growth but did not inhibit human CYP51, demonstrating a >2,000-fold selectivity. This degree of potency and selectivity strongly supports the potential utility of VT-1161 in the treatment of Candida infections.

Resistance to antifungals that target CYP51

Fungal diseases are an increasing global burden. Fungi are now recognised to kill more people annually than malaria, whilst in agriculture, fungi threaten crop yields and food security. Azole resistance, mediated by several mechanisms including point mutations in the target enzyme (CYP51), is increasing through selection pressure as a result of widespread use of triazole fungicides in agriculture and triazole antifungal drugs in the clinic. Mutations similar to those seen in clinical isolates as long ago as the 1990s in Candida albicans and later in Aspergillus fumigatus have been identified in agriculturally important fungal species and also wider combinations of point mutations. Recently, evidence that mutations originate in the field and now appear in clinical infections has been suggested. This situation is likely to increase in prevalence as triazole fungicide use continues to rise. Here, we review the progress made in understanding azole resistance found amongst clinically and agriculturally important fungal species focussing on resistance mechanisms associated with CYP51. Biochemical characterisation of wild-type and mutant CYP51 enzymes through ligand binding studies and azole IC50 determinations is an important tool for understanding azole susceptibility and can be used in conjunction with microbiological methods (MIC50 values), molecular biological studies (site-directed mutagenesis) and protein modelling studies to inform future antifungal development with increased specificity for the target enzyme over the host homologue.

Candida albicans Niche Specialization: Features That Distinguish Biofilm Cells from Commensal Cells

The fungus Candida albicans is a frequent commensal colonizer of the human gastrointestinal (GI) tract, but is also an opportunistic pathogen. This review explores features that distinguish the colonizing and pathogenic forms of C. albicans. Candida albicans in a biofilm is used as an example of a pathogenic form of the organism, because biofilms are a common feature of device-associated C. albicans infections. Biofilms (complex, sessile communities of cells) have been the subject of several large-scale gene expression studies. Biofilms and commensal C. albicans colonizing the murine GI tract show a variety of differentially expressed genes. Cell surface proteins encoded by these differentially expressed genes are especially attractive as targets for new clinical prevention, diagnosis, or treatment tools that are specific for C. albicans in its pathogenic biofilm state.

Immunomodulatory therapy in yeast infections

Invasive yeast infections are a significant cause of morbidity and mortality in patients with defective immune response, such as those with cancer-related immunosuppression, organ transplantation or other immunodeficiencies, and neonates. Hospitalization in the intensive care unit may increase the risk for such infections. Despite the advent of new antifungal agents, the problem is escalating as the number of susceptible hosts increase and virulent, more resistant fungal strains emerge. Over the past few years, advances in immunology and molecular biology have greatly contributed to a better understanding of the pathogenesis of yeast infections. There is evidence that reconstitution of the host immune function is a major contributor to the resolution of yeast infections. Strategies aiming to increase the phagocyte number (e.g., granulocyte transfusions), to stimulate immune response (e.g., administration of hematopoietic growth factors and other proinflammatory cytokines) and to stimulate antigen-specific immunity (e.g., antibody therapy or vaccination) benefit patients at risk of, or suffering from, yeast infections. Further preclinical and clinical studies, as well as improving our understanding of immune system functions and dysfunctions, remain a future challenge.

Opportunistic fungi and fungal infections: the challenge of a single, general antifungal vaccine

A vaccine made up by an algal beta-glucan (laminarin), conjugated with a protein component, protects against infections by different fungi and induces antibodies capable of inhibiting fungal growth. Although taking a premium on a common molecular theme, this remains a sort of 'cross-kingdom' vaccine because the immunizing antigen and the vaccination target belong to organisms from two different kingdoms and this is certainly the first case in the field of human vaccines. Thus, it is possible to convey in a single immunological tool the potential to protect against multiple infections, in theory all those caused by beta-glucan-expressing fungi. The generation of antibodies with the potential to directly inhibit the growth of, or kill the fungal cells also opens an exciting perspective for both active and passive vaccination in immunocompromised subjects.

Intermolecular interaction of voriconazole analogues with model membrane by DSC and NMR, and their antifungal activity using NMR based metabolic profiling

The development of novel antifungal agents with high susceptibility and increased potency can be achieved by increasing their overall lipophilicity. To enhance the lipophilicity of voriconazole, a second generation azole antifungal agent, we have synthesized its carboxylic acid ester analogues, namely p-methoxybenzoate (Vpmb), toluate (Vtol), benzoate (Vbz) and p-nitrobenzoate (Vpnb). The intermolecular interactions of these analogues with model membrane have been investigated using nuclear magnetic resonance (NMR) and differential scanning calorimetric (DSC) techniques. The results indicate varying degree of changes in the membrane bilayer's structural architecture and physico-chemical characteristics which possibly can be correlated with the antifungal effects via fungal membrane. Rapid metabolite profiling of chemical entities using cell preparations is one of the most important steps in drug discovery. We have evaluated the effect of synthesized analogues on Candida albicans. The method involves real time (1)H NMR measurement of intact cells monitoring NMR signals from fungal metabolites which gives Metabolic End Point (MEP). This is then compared with Minimum Inhibitory Concentration (MIC) determined using conventional methods. Results indicate that one of the synthesized analogues, Vpmb shows reasonably good activity.

Azole affinity of sterol 14α-demethylase (CYP51) enzymes from Candida albicans and Homo sapiens

Candida albicans CYP51 (CaCYP51) (Erg11), full-length Homo sapiens CYP51 (HsCYP51), and truncated Δ60HsCYP51 were expressed in Escherichia coli and purified to homogeneity. CaCYP51 and both HsCYP51 enzymes bound lanosterol (K(s), 14 to 18 μM) and catalyzed the 14α-demethylation of lanosterol using Homo sapiens cytochrome P450 reductase and NADPH as redox partners. Both HsCYP51 enzymes bound clotrimazole, itraconazole, and ketoconazole tightly (dissociation constants [K(d)s], 42 to 131 nM) but bound fluconazole (K(d), ~30,500 nM) and voriconazole (K(d), ~2,300 nM) weakly, whereas CaCYP51 bound all five medical azole drugs tightly (K(d)s, 10 to 56 nM). Selectivity for CaCYP51 over HsCYP51 ranged from 2-fold (clotrimazole) to 540-fold (fluconazole) among the medical azoles. In contrast, selectivity for CaCYP51 over Δ60HsCYP51 with agricultural azoles ranged from 3-fold (tebuconazole) to 9-fold (propiconazole). Prothioconazole bound extremely weakly to CaCYP51 and Δ60HsCYP51, producing atypical type I UV-visible difference spectra (K(d)s, 6,100 and 910 nM, respectively), indicating that binding was not accomplished through direct coordination with the heme ferric ion. Prothioconazole-desthio (the intracellular derivative of prothioconazole) bound tightly to both CaCYP51 and Δ60HsCYP51 (K(d), ~40 nM). These differences in binding affinities were reflected in the observed 50% inhibitory concentration (IC(50)) values, which were 9- to 2,000-fold higher for Δ60HsCYP51 than for CaCYP51, with the exception of tebuconazole, which strongly inhibited both CYP51 enzymes. In contrast, prothioconazole weakly inhibited CaCYP51 (IC(50), ~150 μM) and did not significantly inhibit Δ60HsCYP51.

Serological proteome analysis to identify systemic candidiasis patients in the intensive care unit: Analytical, diagnostic and prognostic validation of anti-Candida enolase antibodies on quantitative clinical platforms

Systemic candidiasis (SC) is associated with high morbidity and mortality, because it generally affects patients with severe underlying diseases and its diagnosis is difficult and often delayed, resulting in delayed therapy. We used serological proteome analysis to screen serum anti-Candida IgG antibody-reactivity profiles in 24 patients under intensive care, 12 of which had confirmed SC (fungal cultures), and in 12 healthy subjects. A total of 15 immunogenic proteins from Candida albicans protoplast lysates were differentially immunorecognized by serum IgG antibodies from SC patients compared to controls. Two-way hierarchical clustering and principal-component analyses of these antibody-reactivity patterns accurately differentiated SC patients from controls. Anti-Eno1p IgG antibodies were found to be present at high abundance in SC patients and be an important molecular fingerprint in serum for SC diagnosis. Differential anti-Eno1p IgG antibody reactivity was further validated by a tag capture ELISA and a Western blot assay in 45 SC patients and 118 non-SC subjects. Both quantitative assays provided comparable analytical, diagnostic and prognostic performances, and verified initial proteomic-profiling results. If confirmed in prospective cohort studies, these anti-Eno1p IgG antibodies might be useful for SC diagnosis. However, these, at least as measured by these clinical platforms, appear to have limited prognostic value in SC patients.

Structural analysis and biosynthetic engineering of a solubility-improved and less-hemolytic nystatin-like polyene in Pseudonocardia autotrophica

Polyene antibiotics such as nystatin are a large family of very valuable antifungal polyketide compounds typically produced by soil actinomycetes. Previously, using a polyene cytochrome P450 hydroxylase-specific genome screening strategy, Pseudonocardia autotrophica KCTC9441 was determined to contain an approximately 125.7-kb region of contiguous DNA with a total of 23 open reading frames, which are involved in the biosynthesis and regulation of a structurally unique polyene natural product named NPP. Here, we report the complete structure of NPP, which contains an aglycone identical to nystatin and harbors a unique di-sugar moiety, mycosaminyl-(α1-4)-N-acetyl-glucosamine. A mutant generated by inactivation of a sole glycosyltransferase gene (nppDI) within the npp gene cluster can be complemented in trans either by nppDI-encoded protein or by its nystatin counterpart, NysDI, suggesting that the two sugars might be attached by two different glycosyltransferases. Compared with nystatin (which bears a single sugar moiety), the di-sugar containing NPP exhibits approximately 300-fold higher water solubility and 10-fold reduced hemolytic activity, while retaining about 50% antifungal activity against Candida albicans. These characteristics reveal NPP as a promising candidate for further development into a pharmacokinetically improved, less-cytotoxic polyene antifungal antibiotic.

S279 point mutations in Candida albicans Sterol 14-α demethylase (CYP51) reduce in vitro inhibition by fluconazole

The effects of S279F and S279Y point mutations in Candida albicans CYP51 (CaCYP51) on protein activity and on substrate (lanosterol) and azole antifungal binding were investigated. Both S279F and S279Y mutants bound lanosterol with 2-fold increased affinities (K(s), 7.1 and 8.0 μM, respectively) compared to the wild-type CaCYP51 protein (K(s), 13.5 μM). The S279F and S279Y mutants and the wild-type CaCYP51 protein bound fluconazole, voriconazole, and itraconazole tightly, producing typical type II binding spectra. However, the S279F and S279Y mutants had 4- to 5-fold lower affinities for fluconazole, 3.5-fold lower affinities for voriconazole, and 3.5- to 4-fold lower affinities for itraconazole than the wild-type CaCYP51 protein. The S279F and S279Y mutants gave 2.3- and 2.8-fold higher 50% inhibitory concentrations (IC₅₀s) for fluconazole in a CYP51 reconstitution assay than the wild-type protein did. The increased fluconazole resistance conferred by the S279F and S279Y point mutations appeared to be mediated through a combination of a higher affinity for substrate and a lower affinity for fluconazole. In addition, lanosterol displaced fluconazole from the S279F and S279Y mutants but not from the wild-type protein. Molecular modeling of the wild-type protein indicated that the oxygen atom of S507 interacts with the second triazole ring of fluconazole, assisting in orientating fluconazole so that a more favorable binding conformation to heme is achieved. In contrast, in the two S279 mutant proteins, this S507-fluconazole interaction is absent, providing an explanation for the higher K(d) values observed.

Microbial Conversion of Tomato by a Plant Pathogenic Bacterium Pectobacterium atrosepticum: A Plant-Microbial Approach to Control Pathogenic Candida Species

This study was carried out to produce bioconverted products by microbial fermentation of tomato using a plant pathogenic bacterium Pectobacterium atrosepticum and to evaluate their in vitro antimycotic effect against pathogenic Candida species. The bioconverted products (500 μg/disc) provoked promising antimycotic effects against pathogenic isolates of Candida species as shown by the diameters of zones of inhibition (9 ± 0.6 to 14 ± 0.4 mm), along with their respective minimum inhibitory and minimum fungicidal concentration values, which increased from 250 to 1000 and 250 to 2000 μg/mL, respectively. With the viable counts of the tested fungal pathogens, exposure of the bioconverted products revealed a remarkable antimycotic effect. In addition, the morphology of a clinical isolate of C. glabrata KBN06P00368, visualized by scanning electron microscopy, showed a severe detrimental effect produced by the bioconverted products at the minimum inhibitory concentration (250 μg/mL). The bioconverted products significantly inhibited the in vitro growth of all the tested clinical and pathogenic laboratory isolates of Candida species. This study confirmed the potent antimycotic efficacy of the bioconverted products of tomato, hence justifying the therapeutic uses of bioconverted products in pharmaceutical preparations as an alternative approach to support the antifungal activity of conventional antimycotics.

Synthesis and anticandidal activity of new triazolothiadiazine derivatives

New triazolothiadiazine derivatives were synthesized via the ring closure reaction of 4-amino-5-substituted-2,4-dihydro-3H-1,2,4-triazol-3-thiones with phenacyl bromides. The compounds were tested in vitro against various Candida species and compared with ketoconazole. Among these compounds, the compound bearing cyclohexyl moiety and p-chlorophenyl substituent on triazolothiadiazine ring (2i) was found to be the most potent derivative against Candida albicans (ATCC 90028). It is clear that there is a positive correlation between anticandidal activity and two functional moieties, namely cycloaliphatic group and p-chlorophenyl substituent on triazolothiadiazine ring. The compounds were also investigated for their cytotoxic effects using MTT assay. Compound 2a exhibited the highest cytotoxic activity, whereas compound 2f possessed the lowest cytotoxic activity against NIH/3T3 cells.

Candidemia in children after complex congenital heart defects surgery treated with caspofungin--our own experience and a review of literature

Background

Invasive fungal infections due to Candida species constitute an increasing clinical problem. There are no guidelines for the management of candidemia in children undergoing surgical procedures for congenital heart defects (CHD). The aim of the study was to draw attention to the problem of candidemia in children who are operated on due to congenital heart defects.

Material/Methods

We retrospectively analyzed medical documentation of 307 children with congenital heart defects treated in 1 clinical centre in Poland, from whom we selected those diagnosed with candidemia during the postoperative period. Next, we analyzed in detail the clinical course of invasive candidiasis in each individual and we performed an analysis of risk factors that lead to candidemia.

Results

In the analyzed period, among 307 children who underwent surgical procedures, we observed 2 cases of candidemia (0.65%) which were effectively cured with caspofungin. No adverse effects were observed after treatment with the drug.

Conclusions

Candidemia in children who undergo surgical treatment of congenital heart defects is an important factor that can influence final clinical results. Caspofungin may be an effective therapeutic option when treating candidemia in children after extensive cardiosurgical procedures.