Efficacy of the combination of amphotericin B and echinocandins against Candida auris in vitro and in the Caenorhabditis elegans host model

IMPORTANCE

Multidrug resistance is a rising problem among non-Candida albicans species, such as Candida auris. This therapeutic problem has been very important during the COVID-19 pandemic. The World Health Organization has included C. auris in its global priority list of health-threatening fungi, to study this emerging multidrug-resistant species and to develop effective alternative therapies. In the present study, the synergistic effect of the combination of amphotericin B and echinocandins has been demonstrated against blood isolates of C. auris. Different susceptibility responses were also observed between aggregative and non-aggregative phenotypes. The antifungal activity of these drug combinations against C. auris was also demonstrated in the Caenorhabditis elegans host model of candidiasis, confirming the suitability and usefulness of this model in the search for solutions to antimicrobial resistance.

In Vitro and In Vivo Activity of Citral in Combination with Amphotericin B, Anidulafungin and Fluconazole against Candida auris Isolates

Candida auris is an emerging fungal pathogen responsible for hospital outbreaks of invasive candidiasis associated with high mortality. The treatment of these mycoses is a clinical challenge due to the high resistance levels of this species to current antifungal drugs, and alternative therapeutic strategies are needed. In this study, we evaluated the in vitro and in vivo activities of combinations of citral with anidulafungin, amphotericin B or fluconazole against 19 C. auris isolates. The antifungal effect of citral was in most cases similar to the effect of the antifungal drugs in monotherapy. The best combination results were obtained with anidulafungin, with synergistic and additive interactions against 7 and 11 of the 19 isolates, respectively. The combination of 0.06 μg/mL anidulafungin and 64 μg/mL citral showed the best results, with a survival rate of 63.2% in Caenorhabditis elegans infected with C. auris UPV 17-279. The combination of fluconazole with citral reduced the MIC of fluconazole from > 64 to 1-4 μg/mL against 12 isolates, and a combination of 2 μg/mL fluconazole and 64 μg/mL citral was also effective in reducing mortality in C. elegans. Amphotericin B combined with citral, although effective in vitro, did not improve the activity of each compound in vivo.

PK/PD modeling and simulation of the in vitro activity of the combinations of isavuconazole with echinocandins against Candida auris

In vitro combination of echinocandins and isavuconazole against the emerging species Candida auris is mainly synergistic. However, this combination has not been evaluated in clinical settings. A pharmacokinetic/pharmacodynamic modeling and simulation approach based on in vitro data may be helpful to further study the therapeutic potential of these combinations. Therefore, the aims of this study were to characterize the time course of growth and killing of C. auris in response to the combination of the three approved echinocandins and isavuconazole using a semimechanistic model and to perform model-based simulations in order to predict the in vivo response to combination therapy. In vitro static time-kill curve data for isavuconazole and echinocandins combinations against six blood isolates of C. auris were best modeled considering the total killing of the fungal population as dependent on the additive effects of both drugs. Once assessed, the predictive performance of the model using simulations of different dosing and fungal susceptibility scenarios were conducted. Model-based simulations revealed that none of the combinations at standard or higher dosages would be effective against the studied isolates of C. auris and it was predicted that the combinations of isavuconazole with anidulafungin or caspofungin would be effective for minimum inhibitory concentrations up to 0.03 and 0.06 mg/L respectively, whereas the combination with micafungin would lead to treatment failure. The current approach highlights the importance of bridging the in vitro results to the clinic.

Assessing pH-dependent activities of virulence factors secreted by Candida albicans

Candida albicans is an opportunistic pathogen that can thrive under adverse conditions including suboptimal pH, nutrient scarcity, and low levels of oxygen. Its pathogenicity is associated with the production of virulence factors such as extracellular hydrolytic enzymes and toxins. This study was aimed at determining the effect of external pH, substrate nature, and strain origin on protease, lipase, and hemolysin production. To achieve this objective, agar plate assays were performed at pH 5.0, 6.5, and 7.5 with substrates suitable for the detection of each family of enzymes. Moreover, the study was conducted with 20 clinical C. albicans isolates from blood, oral cavity, skin, urine, and vagina. The hydrolytic zones formed around the colonies were further measured to calculate the Ez (enzymatic zone) indexes. We found that detection of proteases in skim milk agar plates was possible for most isolates only at pH 5 (80%) and pH 6.5 (75%), whereas BSA plates could confer protease detection exclusively at pH 5 (80%). Similarly, the percentage of isolates possessing lipolytic activities was higher at pH 5 (90%) than at pH 6.5 (70%) and pH 7.5 (35%). In contrast, hemolytic activities were detected in all isolates at pH 6.5 and 7.5 but not at pH 5. Further analysis revealed that some differences in the detected activities could potentially be attributed to the anatomical origin of these isolates. Collectively, these findings suggest that the pH of the site of infection might be critical for mimicking the microenvironment employed to experimentally discover the key virulence factors.

Antimicrobial Peptides with Anti-Candida Activity

Mycoses are accountable for millions of infections yearly worldwide. Invasive candidiasis is the most usual, presenting a high morbidity and mortality. Candida albicans remains the prevalent etiologic agent, but the incidence of other species such as Candida parapsilosis, Candida glabrata and Candida auris keeps increasing. These pathogens frequently show a reduced susceptibility to commonly used antifungal drugs, including polyenes, triazoles and echinocandins, and the incidence of emerging multi-drug-resistant strains of these species continues to increase. Therefore, the need to search for new molecules that target these pathogenic species in a different manner is now more urgent than ever. Nature is an almost endless source of interesting new molecules that could meet this need. Among these molecules, antimicrobial peptides, present in different sources in nature, possess some advantages over conventional antifungal agents, even with their own drawbacks, and are considered as a promising pharmacological option against a wide range of microbial infections. In this review, we describe 20 antimicrobial peptides from different origins that possess an activity against Candida.

Impact of Aspergillus spp. isolation in the first 24 hours of admission in critically ill patients with severe influenza virus pneumonia

OBJECTIVE

To determine the incidence and impact of Aspergillus spp. isolation (AI) on ICU mortality in critically ill patients with severe influenza pneumonia during the first 24h of admission.

DESIGN

Secondary analysis of an observational and prospective cohort study.

SETTING

ICUs voluntary participating in the Spanish severe Influenza pneumonia registry, between June 2009 and June 2019.

PATIENTS

Consecutive patients admitted to the ICU with diagnosis of severe influenza pneumonia, confirmed by real-time polymerase chain reaction.

INTERVENTIONS

None.

MAIN VARIABLES OF INTEREST

Incidence of AI in respiratory samples. Demographic variables, comorbidities, need for mechanical ventilation and the presence of shock according at admission. Acute Physiology and Chronic Health Evaluation II (APACHE II) scale calculated on ICU admission.

RESULTS

3702 patients were analyzed in this study. AI incidence was 1.13% (n=42). Hematological malignancies (OR 4.39, 95% CI 1.92-10.04); HIV (OR 3.83, 95% CI 1.08-13.63), and other immunosuppression situations (OR 4.87, 95% CI 1.99-11.87) were factors independently associated with the presence of Aspergillus spp. The automatic CHAID decision tree showed that hematologic disease with an incidence of 3.3% was the most closely AI related variable. Hematological disease (OR 2.62 95% CI 1.95-3.51), immunosuppression (OR 2.05 95% CI 1.46-2.88) and AI (OR 3.24, 95% CI 1.60-6.53) were variables independently associated with ICU mortality.

CONCLUSIONS

Empirical antifungal treatment in our population may only be justified in immunocompromised patients. In moderate-high risk cases, active search for Aspergillus spp. should be implemented.

Postantifungal Effect of Antifungal Drugs against Candida: What Do We Know and How Can We Apply This Knowledge in the Clinical Setting?

The study of the pharmacological properties of an antifungal agent integrates the drug pharmacokinetics, the fungal growth inhibition, the fungicidal effect and the postantifungal activity, laying the basis to guide optimal dosing regimen selection. The current manuscript reviews concepts regarding the postantifungal effect (PAFE) of the main classes of drugs used to treat Candida infections or candidiasis. The existence of PAFE and its magnitude are highly dependent on both the fungal species and the class of the antifungal agent. Therefore, the aim of this article was to compile the information described in the literature concerning the PAFE of polyenes, azoles and echinocandins against the Candida species of medical interest. In addition, the mechanisms involved in these phenomena, methods of study, and finally, the clinical applicability of these studies relating to the design of dosing regimens were reviewed and discussed. Additionally, different factors that could determine the variability in the PAFE were described. Most PAFE studies were conducted in vitro, and a scarcity of PAFE studies in animal models was observed. It can be stated that the echinocandins cause the most prolonged PAFE, followed by polyenes and azoles. In the case of the triazoles, it is worth noting the inconsistency found between in vitro and in vivo studies.

In Vitro Antifungal Activity of Ibrexafungerp (SCY-078) Against Contemporary Blood Isolates From Medically Relevant Species of Candida: A European Study

Background

Ibrexafungerp (SCY-078) is the newest oral and intravenous antifungal drug with broad activity, currently undergoing clinical trials for invasive candidiasis.

Objective

The aim of this study was to assess the in vitro activity of ibrexafungerp and comparators against a collection of 434 European blood isolates of Candida.

Methods

Ibrexafungerp, caspofungin, fluconazole, and micafungin minimum inhibitory concentrations (MICs) were collected from 12 European laboratories for 434 blood isolates, including 163 Candida albicans, 108 Candida parapsilosis, 60 Candida glabrata, 40 Candida tropicalis, 29 Candida krusei, 20 Candida orthopsilosis, 6 Candida guilliermondii, 2 Candida famata, 2 Candida lusitaniae, and 1 isolate each of Candida bracarensis, Candida catenulata, Candida dubliniensis, and Candida kefyr. MICs were determined by the EUCAST broth microdilution method, and isolates were classified according to recommended clinical breakpoints and epidemiological cutoffs. Additionally, 22 Candida auris from different clinical specimens were evaluated.

Results

Ibrexafungerp MICs ranged from 0.016 to ≥8 mg/L. The lowest ibrexafungerp MICs were observed for C. albicans (geometric MIC 0.062 mg/L, MIC range 0.016–0.5 mg/L) and the highest ibrexafungerp MICs were observed for C. tropicalis (geometric MIC 0.517 mg/L, MIC range 0.06–≥8 mg/L). Modal MICs/MIC₅₀s (mg/L) against Candida spp. were 0.125/0.06 for C. albicans, 0.5/0.5 for C. parapsilosis, 0.25/0.25 for C. glabrata, 0.5/0.5 for C. tropicalis, 1/1 for C. krusei, 4/2 for C. orthopsilosis, and 0.5/0.5 for C. auris. Ibrexafungerp showed activity against fluconazole- and echinocandin-resistant isolates. If adopting wild-type upper limits, a non-wild-type phenotype for ibrexafungerp was only observed for 16/434 (3.7%) isolates: 11 (4.6%) C. parapsilosis, 4 (5%) C. glabrata, and 1 (2.5%) C. tropicalis.

Conclusion

Ibrexafungerp showed a potent in vitro activity against Candida.

In vitro and in vivo anti-Candida activity of citral in combination with fluconazole

Background

The ability of Candida to develop biofilms on inert surfaces or living tissues favors recalcitrant and chronic candidiasis associated, in many instances, with resistance to current antifungal therapy.

Aim

The aim of this study was to evaluate the antifungal activity of citral, a phytocompound present in lemongrass essential oil, in monotherapy and combined with fluconazole against azole-resistant Candida planktonic cells and biofilms. The effect of citral combined with fluconazole was also analysed with regard to the expression of fluconazole resistance-associated genes in Candida albicans and the effectiveness of the combination therapy in a Caenorhabditis elegans model of candidiasis.

Results

Citral reduced biofilm formation at initial stages and the metabolic activity of the mature biofilm. The combination of citral with fluconazole was synergistic, with a significant increase in the survival of C. elegans infected with Candida. RNA analysis revealed a reduction of the expression of the efflux pump encoded by MDR1, leading to a greater effect of fluconazole.

Conclusion

Citral in monotherapy and in combination with fluconazole could represent an interesting therapy to treat recalcitrant Candida infections associated to biofilms.

Candidiasis by Candida glabrata, Candida nivariensis and Candida bracarensis in Galleria mellonella: Virulence and Therapeutic Responses to Echinocandins

Candida albicans is the major etiological agent of invasive candidiasis but the increasing prevalence of emerging species of Candida, such as Candida glabrata and phylogenetically closely related species, Candida nivariensis and Candida bracarensis, requires special attention. Differences in virulence among these species and their therapeutic responses using in vivo non-mammalian models are scarcely analysed. The aim of this study was analyse the survival of G. mellonella and host-pathogen interactions during infection by C. glabrata, C. nivariensis and C. bracarensis. Moreover, therapeutic responses to echinocandins were also assessed in the G. mellonella model of candidiasis. These three species produced lethal infection in G. mellonella; C. glabrata was the most virulent species and C. bracarensis the less. Haemocytes of G. mellonella phagocytised C. bracarensis cells more effectively than those of the other two species. Treatment with caspofungin and micafungin was most effective to protect larvae during C. glabrata and C. nivariensis infections while anidulafungin was during C. bracarensis infection. The model of candidiasis in G. mellonella is simple and appropriate to assess the virulence and therapeutic response of these emerging Candida species. Moreover, it successfully allows for detecting differences in the immune system of the host depending on the virulence of pathogens.

In Vitro Pharmacokinetic/Pharmacodynamic Modelling and Simulation of Amphotericin B against Candida auris

The aims of this study were to characterize the antifungal activity of amphotericin B against Candida auris in a static in vitro system and to evaluate different dosing schedules and MIC scenarios by means of semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) modelling and simulation. A two-compartment model consisting of a drug-susceptible and a drug-resistant subpopulation successfully characterized the time-kill data and a modified E_max sigmoidal model best described the effect of the drug. The model incorporated growth rate constants for both subpopulations, a death rate constant and a transfer constant between both compartments. Additionally, the model included a parameter to account for the delay in growth in the absence or presence of the drug. Amphotericin B displayed a concentration-dependent fungicidal activity. The developed PK/PD model was able to characterize properly the antifungal activity of amphotericin B against C. auris. Finally, simulation analysis revealed that none of the simulated standard dosing scenarios of 0.6, 1 and 1.5 mg/kg/day over a week treatment showed successful activity against C. auris infection. Simulations also pointed out that an MIC of 1 mg/L would be linked to treatment failure for C. auris invasive infections and therefore, the resistance rate to amphotericin B may be higher than previously reported.

In vitro activities of carvacrol, cinnamaldehyde and thymol against Candida biofilms

Oral candidiasis is frequently associated with Candida biofilms. Biofilms are microbial communities related to persistent, recalcitrant and difficult to-treat infections. Conventional treatments are not sufficient to overcome biofilm-associated candidiasis; thus, the search of new antifungal compounds is necessary. In the current study, we have evaluated the effect of three phytocompounds, carvacrol, cinnamaldehyde and thymol, against Candida planktonic and sessile cells. Reduction in biofilm biomass and metabolic activity was assessed during adhesion and mature biofilm phases. Candida albicans was the most biofilm-producing Candida species. All phytocompounds tested were fungicidal against Candida planktonic cells. Cinnamaldehyde was the most active in inhibiting biofilm adhesion, but carvacrol and thymol significantly reduced both mature biofilm biomass and metabolic activity. These results highlight the role of cinnamaldehyde, carvacrol and thymol as promising alternatives for the treatment of candidiasis due to their antibiofilm capacities, and stress the necessity to continue studies on their safety, toxicity and pharmacodynamics and pharmacokinetics.

In Vitro Interaction and Killing-Kinetics of Amphotericin B Combined with Anidulafungin or Caspofungin against Candida auris

Treatment of invasive infections caused by Candida auris is challenging due to the limited therapeutic options. The combination of antifungal drugs may be an interesting and feasible approach to be investigated. The aim of this study was to examine the in vitro activity of amphotericin B in combination with anidulafungin or caspofungin against C. auris. In vitro static time–kill curve experiments were conducted for 48 h with different combinations of amphotericin B with anidulafungin or caspofungin against six blood isolates of C. auris. The antifungal activity of 0.5 mg/L of amphotericin B was limited against the six isolates of C. auris. Similarly, echinocandins alone had a negligible effect, even at the highest tested concentrations. By contrast, 1 mg/L of amphotericin B showed fungistatic activity. Synergy was rapidly achieved (8 h) with 0.5 mg/L of amphotericin B plus 2 mg/L of anidulafungin or caspofungin. These combinations lead to a sustained fungistatic effect, and the fungicidal endpoint was reached against some C. auris isolates. Additionally, ≥0.5 mg/L of either of the two echinocandins with 1 mg/L of amphotericin B resulted in fungicidal effect against all C. auris isolates. In conclusion, combinations of amphotericin B with anidulafungin or caspofungin provided greater killing with a lower dose requirement for amphotericin B compared to monotherapy, with synergistic and/or fungicidal outcomes.

Virulence of Candida auris from different clinical origins in Caenorhabditis elegans and Galleria mellonella host models

Candida auris is an emerging multidrug-resistant fungal pathogen responsible for nosocomial outbreaks of invasive candidiasis. Although several studies on the pathogenicity of this species have been reported, the knowledge on C. auris virulence is still limited. This study aims to analyze the pathogenicity of C. auris, using one aggregating isolate and eleven non-aggregating isolates from different clinical origins (blood, urine and oropharyngeal specimens) in two alternative host models of candidiasis: Caenorhabditis elegans and Galleria mellonella. Furthermore, possible associations between virulence, aggregation, biofilm-forming capacity, and clinical origin were assessed. The aggregating phenotype isolate was less virulent in both in vivo invertebrate infection models than non-aggregating isolates but showed higher capacity to form biofilms. Blood isolates were significantly more virulent than those isolated from urine and respiratory specimens in the G. mellonella model of candidiasis. We conclude that both models of candidiasis present pros and cons but prove useful to evaluate the virulence of C. auris in vivo. Both models also evidence the heterogeneity in virulence that this species can develop, which may be influenced by the aggregative phenotype and clinical origin.

Fungal co-infection in COVID-19 patients: Should we be concerned?

Critically ill COVID-19 patients have higher pro-inflammatory (IL-1, IL-2, IL-6, tumor necrosis alpha) and anti-inflammatory (IL-4, IL-10) cytokine levels, less CD₄ interferon-gamma expression, and fewer CD₄ and CD₈ cells. This severe clinical situation increases the risk of serious fungal infections, such as invasive pulmonary aspergillosis, invasive candidiasis or Pneumocystis jirovecii pneumonia. However, few studies have investigated fungal coinfections in this population. We describe an update on published reports on fungal coinfections and our personal experience in three Spanish hospitals. We can conclude that despite the serious disease caused by SARS-CoV-2 in many patients, the scarcity of invasive mycoses is probably due to the few bronchoscopies and necropsies performed in these patients because of the high risk in aerosol generation. However, the presence of fungal markers in clinically relevant specimens, with the exception of bronchopulmonary colonization by Candida, should make it advisable to early implement antifungal therapy.

Synthesis, Physical, Mechanical and Antibacterial Properties of Nanocomposites Based on Poly(vinyl alcohol)/Graphene Oxide-Silver Nanoparticles

The design of new materials with antimicrobial properties has emerged in response to the need for preventing and controlling the growth of pathogenic microorganisms without the use of antibiotics. In this study, partially reduced graphene oxide decorated with silver nanoparticles (GO-AgNPs) was incorporated as a reinforcing filler with antibacterial properties to poly(vinyl alcohol) (PVA) for preparation of poly(vinyl alcohol)/graphene oxide-silver nanoparticles nanocomposites (PVA/GO-AgNPs). AgNPs, spherical in shape and with an average size of 3.1 nm, were uniformly anchored on the partially reduced GO surface. PVA/GO-AgNPs nanocomposites showed exfoliated structures with improved thermal stability, tensile properties and water resistance compared to neat PVA. The glass transition and crystallization temperatures of the polymer matrix increased with the incorporation of the hybrid. The nanocomposites displayed antibacterial activity against Staphylococcus aureus and Escherichia coli in a filler content- and time-dependent manner. S. aureus showed higher susceptibility to PVA/GO-AgNPs films than E. coli. Inhibitory activity was higher when bacterial cells were in contact with nanocomposite films than when in contact with leachates coming out of the films. GO-AgNPs based PVA nanocomposites could find application as wound dressings for wound healing and infection prevention.

Graphene Oxide-Silver Nanoparticle Nanohybrids: Synthesis, Characterization, and Antimicrobial Properties

Drug resistance of pathogenic microorganisms has become a global public health problem, which has prompted the development of new materials with antimicrobial properties. In this context, antimicrobial nanohybrids are an alternative due to their synergistic properties. In this study, we used an environmentally friendly one-step approach to synthesize graphene oxide (GO) decorated with silver nanoparticles (GO-AgNPs). By this process, spherical AgNPs of average size less than 4 nm homogeneously distributed on the surface of the partially reduced GO can be generated in the absence of any stabilizing agent, only with ascorbic acid (L-AA) as a reducing agent and AgNO3 as a metal precursor. The size of the AgNPs can be controlled by the AgNO3 concentration and temperature. Smaller AgNPs are obtained at lower concentrations of the silver precursor and lower temperatures. The antimicrobial properties of nanohybrids against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, Gram-positive Staphylococcus aureus, and the yeast Candida albicans were found to be concentration- and time-dependent. C. albicans and S. aureus showed the highest susceptibility to GO-AgNPs. These nanohybrids can be used as nanofillers in polymer nanocomposites to develop materials with antimicrobial activity for applications in different areas, and another potential application could be cancer therapeutic agents.

Candida albicans biofilms on different materials for manufacturing implant abutments and prostheses

BACKGROUND

Morphological, physical and chemical properties of both implants and prostheses can determine the biofilm formation on their surface and increase the risk of biological complications. The aim of this study was to evaluate the capacity of biofilm formation of Candida albicans on different materials used to manufacture abutments and prostheses.

MATERIAL AND METHODS

Biofilm formation was analyzed on cp grade II titanium, cobalt-chromium alloy and zirconia, silicone, acrylic resin (polymethylmethacrylate) and nano-hybrid composite. Some samples were partially covered with lithium disilicate glass ceramic to study specifically the junction areas.C. albicans was incubated in a biofilm reactor at 37 °C with agitation. The biofilm formation was evaluated at 24 and 48 hours. In addition, the morphology of the biofilm was evaluated by scanning electron microscopy.

RESULTS

C. albicans developed biofilms on the surface of all materials tested. Cobalt-chromium alloy showed the lowest density of adhered biofilm, followed by zirconia and titanium. Silicone and resin showed up to 20 times higher density of biofilm. A higher biofilm formation was observed when junctions of materials presented micropores or imperfections.

CONCLUSIONS

The biofilm formed in the three materials used in the manufacture of abutments and prostheses showed no major differences, being far less dense than in the resins. Two clinical recommendations can be made: to avoid the presence of resins in the subgingival area of implant prostheses and to design prostheses placing cobalt-chromium alloy/ceramic or titanium/ceramic junctions as far as possible from implants.

Disinfectant Activity of A Portable Ultraviolet C Equipment

Healthcare-associated infections (HAIs) can be caused by microorganisms present in common practice instruments generating major health problems in the hospital environment. The aim of this work was to evaluate the disinfection capacity of a portable ultraviolet C equipment (UV Sanitizer Corvent^® -UVSC-) developed to disinfect different objects. For this purpose, six pathogens causing HAIs: Acinetobacter baumannii, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans, were inoculated on slides and discs of different biomaterials (borosilicate, polycarbonate, polyurethane, silicone, Teflon and titanium) and exposed to ultraviolet C radiation. UVSC disinfection was compared with ethanol and chlorhexidine antimicrobial activities following the standards EN14561 and EN14562. Disinfection, established as a reduction of five logarithms from the initial inoculum, was achieved with the UVSC at 120 s of exposure time, with and without the presence of organic matter. The disinfectant effect was observed against S. aureus, P. aeruginosa, E. coli, B. subtilis and C. albicans (reduction >99.999%). Disinfection was also achieved with 70% ethanol and 2% chlorhexidine. As conclusion, UVSC was effective disinfecting the most contaminated surfaces assayed, being a promising alternative for disinfecting hospital materials and inanimate objects that cannot be immersed in liquid biocides, reducing the risk of pathogen transmission.

Effect of biomaterials hydrophobicity and roughness on biofilm development

Most hospitalized patients are carriers of biomedical devices. Infections associated with these devices cause great morbidity and mortality, especially in patients in intensive care units. Numerous strategies have been designed to prevent biofilm development on biodevices. However, biofilm formation is a complex process not fully clarified. In the current study, roughness and hydrophobicity of different biomaterials was analyzed to assess their influences on the biofilm formation of four leading etiological causes of healthcare-associated infections, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis and Candida albicans, using a CDC biofilm reactor. Hydrophobic materials allowed the formation of more abundant and profuse biofilms. Roughness had effect on biofilm formation, but its influence was not significant when material hydrophobicity was considered.

Postantifungal effect of anidulafungin against Candida albicans, Candida dubliniensis, Candida africana, Candida parapsilosis, Candida metapsilosis and Candida orthopsilosis

OBJECTIVE

Candida albicans remains the most common aetiology of invasive candidiasis, leading to high morbidity and mortality. Nevertheless, the incidence of candidiasis due to non-C. albicans species, such as Candida parapsilosis, is increasing. Postantifungal effect (PAFE) is relevant for establishing dosage schedules in antifungal therapy, as the frequency of antifungal administration could change depending on PAFE. The aim of this study was to evaluate the PAFE of anidulafungin against C. albicans, Candida dubliniensis, Candida africana, C. parapsilosis, Candida metapsilosis and Candida orthopsilosis.

METHODS

Twenty-one Candida strains were evaluated. Cells were exposed to anidulafungin for 1 h at concentrations ranging from 0.12 to 8 mg/L for PAFE studies. Time-kill experiments (TK) were conducted at the same concentrations. The experiments were performed using an inoculum of 1-5 x 105 cells/mL and 48 h incubation. Readings of PAFE and TK were done at 0, 2, 4, 6, 24 and 48 h.

RESULTS

Anidulafungin was fungicidal against 2 out of 14 (14%) strains of C. albicans related species in PAFE experiments. Moreover, 2 mg/L of anidulafungin exerted a prolonged PAFE (≥ 33.6 h) against 13 out of 14 (93%) strains. Similarly, fungicidal endpoint was achieved against 1 out of 7 (14%) strains of C. parapsilosis complex, being PAFE prolonged (≥ 42 h) against 6 out of 7 (86%) strains.

CONCLUSIONS

Anidulafungin induced a significant and prolonged PAFE against C. albicans and C. parapsilosis and their related species.

Killing kinetics of anidulafungin, caspofungin and micafungin against Candida parapsilosis species complex: Evaluation of the fungicidal activity

BACKGROUND

Candida parapsilosis, Candida metapsilosis and Candida orthopsilosis are emerging as relevant causes of candidemia. Moreover, they show differences in their antifungal susceptibility and virulence. The echinocandins are different in terms of in vitro antifungal activity against Candida. Time-kill (TK) curves represent an excellent approach to evaluate the fungicidal activity of antifungal drugs.

AIMS

To compare the fungicidal activities of anidulafungin, caspofungin and micafungin against C. parapsilosis species complex by TK curves.

METHODS

Antifungal activities of three echinocandins against C. parapsilosis, C. metapsilosis and C. orthopsilosis were studied by TK curves. Drug concentrations assayed were 0.25, 2 and 8μg/ml. CFU/ml were determined at 0, 2, 4, 6, 24 and 48h.

RESULTS

Killing activities of echinocandins were species-, isolates- and concentration-dependent. Anidulafungin reached the fungicidad endpoint for 6 out of 7 isolates (86%); it required between 13.34 and 29.67h to reach this endpoint for the three species studied, but more than 48h were needed against one isolate of C. orthopsilosis (8μg/ml). Caspofungin fungicidal endpoint was only achieved with 8μg/ml against one isolate of C. metapsilosis after 30.12h (1 out of 7 isolates; 14%). Micafungin fungicidal endpoint was reached in 12.74-28.38h (8μg/ml) against one isolate each of C. parapsilosis and C. orthopsilosis, and against both C. metapsilosis isolates (4 out of 7 isolates; 57%).

CONCLUSIONS

C. metapsilosis was the most susceptible species to echinocandins, followed by C. orthopsilosis and C. parapsilosis. Anidulafungin was the most active echinocandin against C. parapsilosis complex.

Therapeutic tools for oral candidiasis: Current and new antifungal drugs

BACKGROUND

Candidiasis is one of the most common opportunistic oral infections that presents different acute and chronic clinical presentations with diverse diagnostic and therapeutic approaches. The present study carries out a bibliographic review on the therapeutic tools available against oral candidiasis and their usefulness in each clinical situation.

MATERIAL AND METHODS

Recent studies on treatment of oral candidiasis were retrieved from PubMed and Cochrane Library.

RESULTS

Nystatin and miconazole are the most commonly used topical antifungal drugs. Both antifungal drugs are very effective but need a long time of use to eradicate the infection. The pharmacological presentations of miconazole are more comfortable for patients but this drug may interact with other drugs and this fact should be assessed before use. Other topical alternatives for oral candidiasis, such as amphotericin B or clotrimazole, are not available in many countries. Oral fluconazole is effective in treating oral candidiasis that does not respond to topical treatment. Other systemic treatment alternatives, oral or intravenous, less used are itraconazole, voriconazole or posaconazole. Available novelties include echinocandins (anidulafungin, caspofungin) and isavuconazole. Echinocandins can only be used intravenously. Isavuconazole is available for oral and intravenous use. Other hopeful alternatives are new drugs, such as ibrexafungerp, or the use of antibodies, cytokines and antimicrobial peptides.

CONCLUSIONS

Nystatin, miconazole, and fluconazole are very effective for treating oral candidiasis. There are systemic alternatives for treating recalcitrant infections, such as the new triazoles, echinocandins, or lipidic presentations of amphotericin B.

Antifungal Activity of the Human Uterine Cervical Stem Cells Conditioned Medium (hUCESC-CM) Against Candida albicans and Other Medically Relevant Species of Candida

Background: Candidiasis is a major cause of human morbidity and mortality. Human uterine cervical stem cells conditioned medium (hUCESC-CM) is obtained from stromal stem cells of the cervical transformation zone, which are in permanent contact with a wide array of potential vaginal pathogens. In previous reports we have found that hUCESC-CM has antitumor and antibacterial potential. Since Candida is the most prevalent yeast in the human vagina, it seems plausible that hUCESC-CM might also show activity against it. Methods: In a preliminary step, to evaluate if hUCESC-CM showed any activity at all on Candida growth, in vitro activities of hUCESC-CM against fluconazole-susceptible reference strains of Candida albicans, Candida glabrata, Candida krusei, and Candida parapsilosis were studied with a microdilution method on RPMI 1640, using the BioScreen C microbiological incubator. Each measurement was repeated five times. The same methodology was used subsequently on fluconazole-susceptible and fluconazole-resistant Candida isolates from blood and vagina of those species corresponding to the reference strains of Candida against which activity had been detected in the previous study. Moreover, two fluconazole-resistant clinical isolates of Candida auris from blood and urine were also included. Findings: In vitro inhibitory activity of hUCESC-CM ranged from 57.5 to 96.6% growth-reduction against fluconazole-susceptible reference strains of Candida albicans, Candida glabrata, and Candida parapsilosis. hUCESC-CM also reduced the growth of all fluconazole-susceptible tested vaginal isolates by more than 50%. For fluconazole-resistant isolates, growth-reduction was higher than 67% for Candida albicans, regardless of its origin (vagina or blood). The isolate of Candida auris from urine with a MIC > 128 μ/ml for fluconazole was also significantly inhibited. However, hUCESC-CM was almost inactive against any of the fluconazole-resistant blood isolates of Candida glabrata, Candida parapsilosis, and Candida auris tested. Interpretation: This is the first report about the growth-inhibiting properties of conditioned medium from human stromal stem cells against different species of Candida. Antifungal activity of stromal stem cells depends on their site of origin, being most effective against Candida species most prevalent at that particular location. If confirmed in further studies, these findings might result in a completely new therapeutic approach against superficial and invasive candidiasis.

Design and validation of a multiplex PCR protocol for microsatellite typing of Candida parapsilosis sensu stricto isolates

BACKGROUND

Analysis of polymorphic microsatellite markers (STR) is a helpful genotyping technique to differentiate Candida parapsilosis sensu stricto isolates. The aim of this study is to develop and perform an initial validation of an alternative protocol for the reliable and accurate microsatellite genotyping of C. parapsilosis sensu stricto isolates using high-throughput multiplex PCR. To achieve this, the results obtained using the new protocol were compared to the ones obtained using a previously described reference method. To that end, diagnostic accuracy, informativeness and discrimination parameters were estimated.

RESULTS

Our results showed good concordance between both methods (Kappa index: 0.920), leading to a high sensitivity (1; CI(95%) (0.991-1)) and specificity (1; CI(95%) (0.772-1)) after the validation of the new protocol. Moreover, the electropherograms profiles obtained with the new PCR scheme showed a high signal to noise ratio (SNR).

CONCLUSIONS

The new multiplex protocol is valuable for the differentiation of C. parapsilosis sensu stricto, with direct clinical applications. Besides, the new protocol represents a shortening the hands-on time, reducing the sample manipulation (dismissing the possibility of cross-contamination), maintaining the quality of the results (when compared to the ones obtained with the reference method), and helping to the standardization and simplification of the genotyping scheme.

Oral Candida colonization in patients with chronic periodontitis. Is there any relationship?

BACKGROUND

Candida can be implicated in the pathology of chronic periodontitis.

AIMS

To analyze the oral Candida carriage in patients suffering from chronic periodontitis (CP) and its correlation with the severity of this condition.

METHODS

Microbiological samples were taken from 155 patients using the oral rinse (OR) technique and by using paper points in the periodontal pockets (GPP). These patients were divided into 3 groups: 89 patients without CP (control), 47 with moderate CP, and 19 with severe CP. Samples were cultured in a Candida chromogenic agar for Candida. Species were identified by microbiological and molecular methods.

RESULTS

Candida was isolated in the OR of 45 (50.6%), 21 (44.7%), and 11 (57.9%) patients, respectively, and in the GPP of 32 (36%), 14 (29.2%), and 10 (42.6%) patients from the control, moderate CP and severe CP groups, respectively. Candida was isolated more frequently and in a greater burden in OR than in GPP (p<0.01). Candida albicans was the most prevalent species. GPP of patients with CP had poor fungal biodiversity (p<0.01).

CONCLUSIONS

Colonization by Candida was present in the samples of patients without CP, and with both moderate and severe CP. Nonetheless, patients with severe CP had a higher rate of Candida colonization, especially by C. albicans.

Prevalence and antifungal susceptibility profiles of Candida glabrata, Candida parapsilosis and their close-related species in oral candidiasis

OBJECTIVE

To evaluate the importance of Candida glabrata, Candida parapsilosis and their close-related species, Candida bracarensis, Candida nivariensis, Candida metapsilosis and Candida orthopsilosis in patients with oral candidiasis and, to determine the in vitro activities of antifungal drugs currently used for the treatment.

METHODS

One hundred fourteen isolates of C. glabrata and 97 of C. parapsilosis, previously identified by conventional mycological methods, were analysed by molecular techniques. In vitro antifungal susceptibility to fluconazole, itraconazole, miconazole, and nystatin was evaluated by CLSI M44-A2 disk diffusion test, and by CLSI M27-A3 microdilution for fluconazole.

RESULTS

All C. glabrata isolates were identified as C. glabrata sensu stricto, 93 out of 97 C. parapsilosis isolates as C. parapsilosis sensu stricto, three as C. orthopsilosis and one as C. metapsilosis. Candida glabrata was mainly isolated in mixed cultures but C. parapsilosis complex was more frequent in pure culture. Candida metapsilosis and C. orthopsilosis were isolated as pure culture and both species were susceptible to all antifungal agents tested. Most C. glabrata isolates were susceptible to miconazole and nystatin, but resistant to fluconazole and itraconazole. Azole cross resistance was also observed. Candida parapsilosis isolates were susceptible to fluconazole although azole cross resistance to miconazole and itraconazole was observed.

CONCLUSION

This study highlights the importance of accurate identification and antifungal susceptibility testing of oral Candida isolates in order to have an in-depth understanding of the role of C. glabrata and C. parapsilosis in oral candidiasis.

EPICO 4.0. 'Total quality' in the management of invasive candidiasis in critically ill patients by analysing the integrated process

BACKGROUND

A high quality integrated process in the clinical setting of non-neutropenic critically ill patients at risk for invasive candidiasis is a necessary tool to improve the management of these patients.

AIMS

To identify the key points on invasive candidiasis in order to develop a set of recommendations with a high level of consensus required for the creation of a total quality integrated process for the management of non-neutropenic critically ill patients at risk of invasive candidiasis.

METHODS

After a thorough review of the literature of the previous five years, a Spanish prospective questionnaire, which measured consensus by the Delphi technique, was anonymously conducted by e-mail, including 31 national multidisciplinary experts with extensive experience in invasive fungal infections, from six national scientific societies. The experts included a specialist in intensive care medicine, anesthetists, microbiologists, pharmacologists, and specialists in infectious diseases that responded 27 questions prepared by the coordination group. The educational objectives considered six processes that included knowledge of the local epidemiology, the creation and development of multidisciplinary teams, the definitions of the process, protocols, and indicators (KPI), an educational phase, hospital implementation, and the measurement of outcomes. The level of agreement among experts in each category to be selected should exceed 70%. In a second phase, after drawing up the recommendations of the selected processes, a face to face meeting with more than 60 specialists was held. The specialists were asked to validate the pre-selected recommendations.

MEASURES AND MAIN OUTCOMES

Firstly, 20 recommendations from all the sections were pre-selected: Knowledge of local epidemiology (3 recommendations), creation and development of multidisciplinary teams (3), definition of the process, protocols and indicators (1), educational phase (3), hospital implementation (3), and measurement of outcomes (7). After the second phase, 18 recommendations were validated, and it was concluded that the minimum team or core necessary for the development of an efficient program in the use of antifungal drugs in non-neutropenic critically ill patients must consist of a specialist in infectious diseases, a clinical pharmacist, a microbiologist, a specialist in intensive care medicine, a specialist in anesthesia and recovery, and an administrator or member of the medical management team, and, in order to be cost-effective, it should be implemented in hospitals with over 200 beds. In addition, it is recommended to apply a consensual check list for the evaluation of the diagnostic process and treatment of invasive candidiasis in patients that have started an antifungal treatment. The management of external knowledge and individual learning stand out as active educational strategies. The main strategies for measuring patient safety outcomes are the analysis of the results achieved, and learning activities; assess, review and refine the deployment of the processes; quality control; epidemiological surveillance and applied research; benchmarking; and basic research. The results of the integrated process should be annually disseminated outside the hospital.

CONCLUSIONS

Optimizing the management of invasive candidiasis requires the application of the knowledge and skills detailed in our recommendations. These recommendations, based on the Delphi methodology, facilitate the creation of a total quality integrated process in critically-ill patients at risk for invasive candidiasis.

Usefulness of the Non-conventional Caenorhabditis elegans Model to Assess Candida Virulence

Invasive candidiasis is caused mainly by Candida albicans, but other Candida species have increasing etiologies. These species show different virulence and susceptibility levels to antifungal drugs. The aims of this study were to evaluate the usefulness of the non-conventional model Caenorhabditis elegans to assess the in vivo virulence of seven different Candida species and to compare the virulence in vivo with the in vitro production of proteinases and phospholipases, hemolytic activity and biofilm development capacity. One culture collection strain of each of seven Candida species (C. albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida metapsilosis, Candida orthopsilosis and Candida parapsilosis) was studied. A double mutant C. elegans AU37 strain (glp-4;sek-1) was infected with Candida by ingestion, and the analysis of nematode survival was performed in liquid medium every 24 h until 120 h. Candida establishes a persistent lethal infection in the C. elegans intestinal tract. C. albicans and C. krusei were the most pathogenic species, whereas C. dubliniensis infection showed the lowest mortality. C. albicans was the only species with phospholipase activity, was the greatest producer of aspartyl proteinase and had a higher hemolytic activity. C. albicans and C. krusei caused higher mortality than the rest of the Candida species studied in the C. elegans model of candidiasis.

In Vitro Antifungal Susceptibility of Oral Candida Isolates from Patients Suffering from Caries and Chronic Periodontitis

Caries and chronic periodontitis are common oral diseases where a higher Candida colonization is reported. Antifungal agents could be adjuvant drugs for the therapy of both clinical conditions. The aim of the current study has been to evaluate the in vitro activities of conventional and new antifungal drugs against oral Candida isolates from patients suffering from caries and/or chronic periodontitis. In vitro activities of amphotericin B, fluconazole, itraconazole, miconazole, nystatin, posaconazole and voriconazole against 126 oral Candida isolates (75 Candida albicans, 18 Candida parapsilosis, 11 Candida dubliniensis, six Candida guilliermondii, five Candida lipolytica, five Candida glabrata, four Candida tropicalis and two Candida krusei) from 61 patients were tested by the CLSI M27-A3 method. Most antifungal drugs were highly active, and resistance was observed in less than 5% of tested isolates. Miconazole was the most active antifungal drug, being more than 98% of isolates susceptible. Fluconazole, itraconazole, and the new triazoles, posaconazole and voriconazole, were also very active. Miconazole, fluconazole and voriconazole have excellent in vitro activities against all Candida isolates and could represent suitable treatment for a hypothetically adjunctive therapy of caries and chronic periodontitis.

Detection and characterization of surface microbial contamination in emergency ambulances

A cross-sectional study was performed in 10 emergency basic life support ambulances operating in Bilbao, Spain, to assess surface bacterial contamination. Presence of clinically relevant bacterial contamination suggests that disinfection of the studied basic life support ambulances was not optimal and represents a potential risk of infection for the patients transferred in them. It is critical to implement existing infection control and prevention protocols to resolve this issue.

Twitter as a Tool for Teaching and Communicating Microbiology: The #microMOOCSEM Initiative

Online social networks are increasingly used by the population on a daily basis. They are considered a powerful tool for science communication and their potential as educational tools is emerging. However, their usefulness in academic practice is still a matter of debate. Here, we present the results of our pioneering experience teaching a full Basic Microbiology course via Twitter (#microMOOCSEM), consisting of 28 lessons of 40-45 minutes duration each, at a tweet per minute rate during 10 weeks. Lessons were prepared by 30 different lecturers, covering most basic areas in Microbiology and some monographic topics of general interest (malaria, HIV, tuberculosis, etc.). Data analysis on the impact and acceptance of the course were largely affirmative, promoting a 330% enhancement in the followers and a >350-fold increase of the number of visits per month to the Twitter account of the host institution, the Spanish Society for Microbiology. Almost one third of the course followers were located overseas. Our study indicates that Massive Online Open Courses (MOOC) via Twitter are highly dynamic, interactive, and accessible to great audiences, providing a valuable tool for social learning and communicating science. This strategy attracts the interest of students towards particular topics in the field, efficiently complementing customary academic activities, especially in multidisciplinary areas like Microbiology.

EPICO 3.0. Management of non-neutropenic patients in medical wards

BACKGROUND

Although the management of invasive fungal infection (IFI) has improved, a number of controversies persist regarding the approach to invasive fungal infection in non-neutropenic medical ward patients.

AIMS

To identify the essential clinical knowledge to elaborate a set of recommendations with a high level of consensus necessary for the management of IFI in non-neutropenic medical ward patients.

METHODS

A prospective, Spanish questionnaire, which measures consensus through the Delphi technique, was anonymously answered and e-mailed by 30 multidisciplinary national experts, all specialists (intensivists, anesthesiologists, microbiologists, pharmacologists and specialists in infectious diseases) in IFI and belonging to six scientific national societies. They responded to five questions prepared by the coordination group after a thorough review of the literature published in the last few years. For a category to be selected, the level of agreement among the experts in each category had to be equal to or greater than 70%. In a second round, 73 specialists attended a face-to-face meeting held after extracting the recommendations from the chosen topics, and validated the pre-selected recommendations and derived algorithm.

RESULTS

The following recommendations were validated and included in the algorithm: 1. several elements were identified as risk factors for invasive candidiasis (IC) in non-hematologic medical patients; 2. no agreement on the use of the colonization index to decide whether prescribing an early antifungal treatment to stable patients (no shock), with sepsis and no other evident focus and IC risk factors; 3. agreement on the use of the Candida Score to decide whether prescribing early antifungal treatment to stable patients (no shock) with sepsis and no other evident focus and IC risk factors; 4. agreement on initiating early antifungal treatment in stable patients (no shock) with a colonization index>0.4, sepsis with no other evident focus and IC risk factors; 5. agreement on the performance of additional procedures in stable patients (no shock) with sepsis and no other evident focus, IC risk factors, without colonization index>0.4, but with a high degree of suspicion.

CONCLUSIONS

Based on the expert's recommendations, an algorithm for the management of non-neutropenic medical patients was constructed and validated. This algorithm may be useful to support bedside prescription.

Impact of a multifaceted educational intervention including serious games to improve the management of invasive candidiasis in critically ill patients

OBJECTIVES

Infections caused by Candida species are common in critically ill patients and contribute to significant morbidity and mortality. The EPICO Project (Epico 1 and Epico 2.0 studies) recently used a Delphi approach to elaborate guidelines for the diagnosis and treatment of this condition in critically ill adult patients. We aimed to evaluate the impact of a multifaceted educational intervention based on the Epico 1 and Epico 2.0 recommendations.

DESIGN

Specialists anonymously responded to two online surveys before and after a multifaceted educational intervention consisting of 60-min educational sessions, the distribution of slide kits and pocket guides with the recommendations, and an interactive virtual case presented at a teleconference and available for online consultation.

SETTING

A total of 74 Spanish hospitals.

PARTICIPANTS

Specialists of the Intensive Care Units in the participating hospitals.

VARIABLES OF INTEREST

Specialist knowledge and reported practices evaluated using a survey. The McNemar test was used to compare the responses in the pre- and post-intervention surveys.

RESULTS

A total of 255 and 248 specialists completed both surveys, in both periods, respectively. The pre-intervention surveys showed many specialists to be unaware of the best approach for managing invasive candidiasis. After both educational interventions, specialist knowledge and reported practices were found to be more in line with nearly all the recommendations of the Epico 1 and Epico 2.0 guidelines, except as regards de-escalation from echinocandins to fluconazole in Candida glabrata infections (p=0.055), and the duration of antifungal treatment in both candidemia and peritoneal candidiasis.

CONCLUSIONS

This multifaceted educational intervention based on the Epico Project recommendations improved specialist knowledge of the management of invasive candidiasis in critically ill patients.

Vancomycin heteroresistant community associated methicillin-resistant Staphylococcus aureus ST72-SCCmecIVa strain colonizing the nostrils of a five-year-old Spanish girl

BACKGROUND AND OBJECTIVES

During a community methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization study, an MRSA strain with vancomycin hetero-resistance (h-VISA) was isolated from a five year-old girl with tetralogy of Fallot without previous exposure to vancomycin. An extended nasal colonization study was performed on all her close relatives.

RESULTS

Only the patient and her sister were colonized by an h-VISA MRSA strain (clone USA 700, ST72, t148, agr 1 and SCCmec IVa). Mupirocin decolonisation was effective in the elder sister. A new nasal decolonisation in the younger girl using fusidic acid was also successful. However, after decolonisation both sisters were colonized by a methicillin-susceptible S. aureus (ST30, t012 and agr 3) previously isolated from their mother's nostrils.

CONCLUSION

As S. aureus have a great capacity to spread among people in close contact, knowledge of a patients' colonization status, tracing contacts, and a correct management are critical issues for the successful containment of multiresistant staphylococci.

Fungal diseases: could nanostructured drug delivery systems be a novel paradigm for therapy?

Invasive mycoses are a major problem for immunocompromised individuals and patients in intensive care units. Morbidity and mortality rates of these infections are high because of late diagnosis and delayed treatment. Moreover, the number of available antifungal agents is low, and there are problems with toxicity and resistance. Alternatives for treating invasive fungal infections are necessary. Nanostructured systems could be excellent carriers for antifungal drugs, reducing toxicity and targeting their action. The use of nanostructured systems for antifungal therapy began in the 1990s, with the appearance of lipid formulations of amphotericin B. This review encompasses different antifungal drug delivery systems, such as liposomes, carriers based on solid lipids and nanostructure lipids, polymeric nanoparticles, dendrimers, and others. All these delivery systems have advantages and disadvantages. Main advantages are the improvement in the antifungal properties, such as bioavailability, reduction in toxicity, and target tissue, which facilitates innovative therapeutic techniques. Conversely, a major disadvantage is the high cost of production. In the near future, the use of nanosystems for drug delivery strategies can be used for delivering peptides, including mucoadhesive systems for the treatment of oral and vaginal candidiasis.

Postantifungal Effect of Micafungin against the Species Complexes of Candida albicans and Candida parapsilosis

Micafungin is an effective antifungal agent useful for the therapy of invasive candidiasis. Candida albicans is the most common cause of invasive candidiasis; however, infections due to non-C. albicans species, such as Candida parapsilosis, are rising. Killing and postantifungal effects (PAFE) are important factors in both dose interval choice and infection outcome. The aim of this study was to determinate the micafungin PAFE against 7 C. albicans strains, 5 Candida dubliniensis, 2 Candida Africana, 3 C. parapsilosis, 2 Candida metapsilosis and 2 Candida orthopsilosis. For PAFE studies, cells were exposed to micafungin for 1 h at concentrations ranging from 0.12 to 8 μg/ml. Time-kill experiments (TK) were conducted at the same concentrations. Samples were removed at each time point (0-48 h) and viable counts determined. Micafungin (2 μg/ml) was fungicidal (≥ 3 log₁₀ reduction) in TK against 5 out of 14 (36%) strains of C. albicans complex. In PAFE experiments, fungicidal endpoint was achieved against 2 out of 14 strains (14%). In TK against C. parapsilosis, 8 μg/ml of micafungin turned out to be fungicidal against 4 out 7 (57%) strains. Conversely, fungicidal endpoint was not achieved in PAFE studies. PAFE results for C. albicans complex (41.83 ± 2.18 h) differed from C. parapsilosis complex (8.07 ± 4.2 h) at the highest tested concentration of micafungin. In conclusion, micafungin showed significant differences in PAFE against C. albicans and C. parapsilosis complexes, being PAFE for the C. albicans complex longer than for the C. parapsilosis complex.

Comparison of the in vitro activity of echinocandins against Candida albicans, Candida dubliniensis, and Candida africana by time-kill curves

Candida albicans remains the most common fungal pathogen. This species is closely related to 2 phenotypically similar cryptic species, Candida dubliniensis and Candida africana. This study aims to compare the antifungal activities of echinocandins against 7 C. albicans, 5 C. dubliniensis, and 2 C. africana strains by time-kill methodology. MIC values were similar for the 3 species; however, differences in killing activity were observed among species, isolates, and echinocandins. Echinocandins produced weak killing activity against the 3 species. In all drugs, the fungicidal endpoint (99.9% mortality) was reached at ≤31 h with ≥0.5 μg/mL for anidulafungin in 4 C. albicans and 1 C. dubliniensis, for caspofungin in 1 C. albicans and 2 C. dubliniensis, and for micafungin in 4 C. albicans and 1 C. dubliniensis. None of echinocandins showed lethality against C. africana. Identification of these new cryptic species and time-kill studies would be recommendable when echinocandin treatment fails.