Dan-Tiberiu Furnica

Aspergillus fumigatus is an opportunistic filamentous fungus that primarily affects the respiratory tract of the human body. Depending on its host’s immune response, the pathogen can cause invasive pulmonary aspergillosis (IPA). Biofilm formation by A. fumigatus increases virulence and resistance against antifungals and immune response and is one important factor in IPA development. Here, two human-like models, precision cut lung slices (PCLS) and a biofilm co-culture model, have been developed to test the anti-biofilm activity of voriconazole, amphotericin B, as well as luliconazole against A. fumigatus. In both assays, metabolically active A. fumigatus biofilms were examined at different biofilm developmental stages using an XTT assay. A decrease in the metabolic activity of the fungal biofilms was detected for each of the tested agents in both assays. Significant anti-biofilm effects exist against early-stage biofilm in the co-culture model. In the PCLS assay, amphotericin B showed the strongest inhibition after 24 h. In conclusion, the applied PCLS ex vivo model can be used to study the property and activity of certain antifungal compounds against Aspergillus biofilm. With its close resemblance to human conditions, the PCLS model has the potential for improving the current understanding of biofilm treatments in laboratory settings.

The diagnosis of invasive pulmonary aspergillosis (IPA) in intensive care unit (ICU) patients is crucial since most clinical signs are not specific to invasive fungal infections. To detect an IPA, different criteria should be considered. Next to host factors and radiological signs, microbiological criteria should be fulfilled. For microbiological diagnostics, different methods are available. Next to the conventional culture-based approaches like staining and culture, non-culture-based methods can increase sensitivity and improve time-to-result. Besides fungal biomarkers, like galactomannan and (1→3)-β-D-glucan as nonspecific tools, molecular-based methods can also offer detection of resistance determinants. The detection of novel biomarkers or targets is promising. In this review, we evaluate and discuss the value of non-culture-based microbiological methods (galactomannan, (1→3)-β-D-glucan, Aspergillus PCR, new biomarker/targets) for diagnosing IPA in ICU patients.

Lomentospora prolificans and S. apiospermum /P. boydii are opportunistic, multidrug-resistant pathogens causing invasive infections in immunosuppressed patients and sometimes in healthy persons. Lomentospora prolificans is panresistant against the currently available antifungals, and both species are associated with high mortality rates. Thus, the discovery of novel antifungal drugs exhibiting an effect against these resistant fungi is crucial.

Aspergillus fumigatus has become a significant threat in clinical settings. Cases of invasive infections with azole-resistant A. fumigatus isolates (ARAF) increased recently. Developing strategies for dealing with ARAF has become crucial. We here investigated the in-vitro and in-vivo activity of the imidazole luliconazole (LLCZ) against clinical ARAF. In total, the LLCZ minimum inhibitory concentrations (MICs) were tested for 101 A. fumigatus isolates (84 ARAF and 17 azole-susceptible A. fumigatus as wild-type controls) according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Additionally, antifungal activity was assessed in vitro, including an XTT planktonic growth kinetics assay and biofilm assays (crystal violet and XTT assay). Further, a single-dose LLCZ treatment (152 mg/L) was tested for seven days in vivo in a Galleria mellonella infection model. LLCZ showed an MIC₅₀ of 0.002 mg/L and no significant difference was found between triazole-resistant and wild-type isolates. Growth inhibition took place between 6 and 12 h after the start of incubation. LLCZ inhibited biofilm formation when added in the pre-adhesion stages. In vivo, single-dose LLCZ-treated larvae show a significantly higher survival percentage than the control group (20%). In conclusion, LLCZ has activity against planktonic cells and early biofilms of ARAF.