Antifungal susceptibility of Candida species using the Clinical and Laboratory Standards Institute disk diffusion and broth microdilution methods

Oropharyngeal Candidiasis among Egyptian COVID-19 Patients: Clinical Characteristics, Species Identification, and Antifungal Susceptibility, with Disease Severity and Fungal Coinfection Prediction Models

The study aimed to investigate the causative species, antifungal susceptibility, and factors associated with oropharyngeal candidiasis (OPC) among Egyptian COVID-19 patients. This is an observational, case-controlled, single-center study that included three groups: COVID-19 patients (30), COVID-19 patients with OPC (39), and healthy individuals (31). Patients’ demographic data (age, sex), laboratory tests, comorbidities, treatment, and outcomes were included. Candida species were isolated from COVID-OPC patient’s oropharyngeal swabs by convenient microbiological methods. Isolated strains were tested for antimicrobial susceptibility, biofilm production, aspartyl protease, and phospholipase activities. The most common respiratory symptoms reported were dyspnea (36/39; 92.4%) and cough (33/39; 84.7%). Candida albicans was the most common isolated species, accounting for 74.36% (29/39), followed by Candida tropicalis and Candida glabrata (15.38% and 10.26%, respectively). Amphotericin was effective against all isolates, while fluconazole was effective against 61.5%. A total of 53.8% of the isolates were biofilm producers. The phospholipase activity of C. albicans was detected among 58.6% (17/29) of the isolates. Significant variables from this study were used to create two equations from a regression model that can predict the severity of disease course and liability to fungal infection, with a stativity of 87% and 91%, respectively. According to our findings, COVID-19 patients with moderate to severe infection under prolonged use of broad-spectrum antibiotics and corticosteroids should be considered a high-risk group for developing OPC, and prophylactic measures are recommended to be included in the treatment protocols. In addition, due to the increased rate of fluconazole resistance, other new antifungals should be considered.

Identification of Dual-Target Compounds with Antifungal and Anti-NLRP3 Inflammasome Activity

Invasive and superficial infections caused by the Candida species result in significant global morbidity and mortality. As the pathogenicity of these organisms is intimately intertwined with host immune response, therapies to target both the fungus and host inflammation may be warranted. Structural similarities exist between established inhibitors of the NLRP3 inflammasome and those of fungal acetohydroxyacid synthase (AHAS). Therefore, we leveraged this information to conduct an in silico molecular docking screen to find novel polypharmacologic inhibitors of these targets that resulted in the identification of 12 candidate molecules. Of these, compound 10 significantly attenuated activation of the NLPR3 inflammasome by LPS + ATP, while also demonstrating growth inhibitory activity against C. albicans that was alleviated in the presence of exogenous branched chain amino acids, consistent with targeting of fungal AHAS. SAR studies delineated an essential molecular scaffold required for dual activity. Ultimately, 10 and its analog 10a resulted in IC50 (IL-1β release) and MIC50 (fungal growth) values with low μM potency against several Candida species. Collectively, this work demonstrates promising potential of dual-target approaches for improved management of fungal infections.

A novel method for synthesis of α-spinasterol and its antibacterial activities in combination with ceftiofur

In this study, we designed a novel method of the synthesis of α-spinasterol from commercially available stigmasterol and explored the combinational effect of the α-spinasterol with ceftiofur in vitro against S. pullorum cvcc533, S. pneumoniae CAU0070, E. coli, and S. aureus. α-Spinasterol was obtained by a key reaction of Bamford-Stevens reaction with a desirable yield for five steps. The combination of α-spinasterol and ceftiofur showed stronger synergetic effect against the four pathogenic strains compared with that of stigmasterol and ceftiofur alone. In time-kill analyses, at concentrations above the MICs, ceftiofur in combination with α-spinasterol exhibited time-dependency and concentration-dependency comparing to time dependency with ceftiofur alone. We conclude that the combination usage of α-spinasterol and ceftiofur is an effective and promising strategy against the four pathogenic bacterial strains in vitro.

Pre-mRNA splicing is modulated by antifungal drugs in the filamentous fungus Neurospora crassa

For this study, we sought to identify pre‐mRNA processing events modulated by changes in extracellular pH, inorganic phosphate, and antifungal drugs. We examined genes with at least four putative introns whose transcriptional level responded to these effectors. We showed that the intron retention levels of genes encoding asparagine synthetase 2, C6‐zinc finger regulator (fluffy), and a farnesyltransferase respond to amphotericin B, ketoconazole, and other effectors. In general, the assayed antifungals promoted the disruption of the structural domains of these proteins probably leading to their inactivation, which emphasize the complexity of the metabolic modulation exerted by antifungal signaling.

Trough concentration of voriconazole and its relationship with efficacy and safety: a systematic review and meta-analysis

This meta-analysis showed trough concentrations of 0.5 mg/L to be the lower limit of voriconazole during treatment, whereas trough concentrations of 3.0 mg/L were associated with an increased risk of moderate to severe hepatotoxicity, particularly for the Asian population.

Objectives

The optimum trough concentration of voriconazole for clinical response and safety is controversial. The objective of this review was to determine the optimum trough concentration of voriconazole and evaluate its relationship with efficacy and safety.

Methods

MEDLINE, EMBASE, ClinicalTrials.gov, the Cochrane Library and three Chinese literature databases were searched. Observational studies that compared clinical outcomes below and above the trough concentration cut-off value were included. We set the trough concentration cut-off value for efficacy as 0.5, 1.0, 1.5, 2.0 and 3.0 mg/L and for safety as 3.0, 4.0, 5.0, 5.5 and 6.0 mg/L. The efficacy outcomes were invasive fungal infection-related mortality, all-cause mortality, rate of successful treatment and rate of prophylaxis failure. The safety outcomes included incidents of hepatotoxicity, neurotoxicity and visual disorders.

Results

A total of 21 studies involving 1158 patients were included. Compared with voriconazole trough concentrations of >0.5 mg/L, levels of <0.5 mg/L significantly decreased the rate of treatment success (risk ratio = 0.46, 95% CI 0.29–0.74). The incidence of hepatotoxicity was significantly increased with trough concentrations >3.0, >4.0, >5.5 and >6.0 mg/L. The incidence of neurotoxicity was significantly increased with trough concentrations >4.0 and >5.5 mg/L.

Conclusions

A voriconazole level of 0.5 mg/L should be considered the lower threshold associated with efficacy. A trough concentration >3.0 mg/L is associated with increased hepatotoxicity, particularly for the Asian population, and >4.0 mg/L is associated with increased neurotoxicity.