Exposure to N-chlorotaurine induces oxidative stress responses in Aspergillus fumigatus

Pathogen-Host Interaction Repertoire at Proteome and Posttranslational Modification Levels During Fungal Infections

Prevalence of fungal diseases has increased globally in recent years, which often associated with increased immunocompromised patients, aging populations, and the novel Coronavirus pandemic. Furthermore, due to the limitation of available antifungal agents mortality and morbidity rates of invasion fungal disease remain stubbornly high, and the emergence of multidrug-resistant fungi exacerbates the problem. Fungal pathogenicity and interactions between fungi and host have been the focus of many studies, as a result, lots of pathogenic mechanisms and fungal virulence factors have been identified. Mass spectrometry (MS)-based proteomics is a novel approach to better understand fungal pathogenicities and host–pathogen interactions at protein and protein posttranslational modification (PTM) levels. The approach has successfully elucidated interactions between pathogens and hosts by examining, for example, samples of fungal cells under different conditions, body fluids from infected patients, and exosomes. Many studies conclude that protein and PTM levels in both pathogens and hosts play important roles in progression of fungal diseases. This review summarizes mass spectrometry studies of protein and PTM levels from perspectives of both pathogens and hosts and provides an integrative conceptual outlook on fungal pathogenesis, antifungal agents development, and host–pathogen interactions.

Activity of N-Chlorotaurine against Long-Term Biofilms of Bacteria and Yeasts

Background: N-chlorotaurine (NCT), an antiseptic that originates from the human defense system, has broad-spectrum microbicidal activity and is well tolerated by human tissue and applicable to sensitive body regions. Bacteria in short-term biofilms, too, have been shown to be killed by NCT. It was the aim of the present study to demonstrate the activity of NCT against bacteria and yeasts in longer-lasting biofilms, including their co-culture. Materials and methods: Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella variicola biofilms were grown for 14 weeks in MBECTM inoculator with 96 well base. Some pegs were pinched off weekly and incubated in 1% NCT in PBS (PBS only for controls) at pH 7.1 and 37 °C, for 30 and 60 min. Subsequently, bacteria were resuspended by ultrasonication and subjected to quantitative cultures. Similar tests were conducted with C. albicans biofilms grown on metal (A2-steel) discs for 4 weeks. Mixed co-cultures of C. albicans plus each of the three bacterial strains on metal discs were grown for 5-7 weeks and weekly evaluated, as mentioned above. Results: Single biofilms of S. aureus, P. aeruginosa, and K. variicola grew to approximately 1 × 106 colony forming units (CFU)/mL and C. albicans to 1 × 105 CFU/mL. In combined biofilms, the CFU count was about 1 log10 lower. Viable counts of biofilms of single bacteria were reduced by 2.8 to 5.6 log10 in 1% NCT after 60 min (0.9 to 4.7 log10 after 30 min) with Gram-negative bacteria being more susceptible than S. aureus. Significant reduction of C. albicans by 2.0 to 2.9 log10 occurred after 4 h incubation. In combined biofilms, viable counts of C. albicans were reduced by 1.1 to 2.4 log10 after 4 h, while they reached the detection limit after 1 to 2 h with bacteria (2.0 to > 3.5 log10 reduction). Remarkably, older biofilms demonstrated no increase in resistance but constant susceptibility to NCT. This was valid for all tested pathogens. In electron microscopy, morphological differences between NCT-treated and non-treated biofilms could be found. Conclusions: NCT is active against long-term biofilms of up to several months irrespective of their age. Combined biofilm cultures of yeasts and bacteria show a similar susceptibility pattern to NCT as single ones. These results contribute to the explanation of the clinical efficacy of NCT, for instance, in infected chronic wounds and purulently coated crural ulcerations.

N-chlorotaurine, a potent weapon against multiresistant bacteria

Aims

N‐chlorotaurine (NCT) is a body‐own mild oxidizing antiseptic that can be applied topically as a well‐tolerated anti‐infective at many body sites. The objective of this study was to demonstrate its activity against representative nosocomial multidrug‐resistant bacteria.

Methods and Results

The bactericidal activity of NCT was tested in quantitative killing assays against a panel of multiresistant Gram‐positive and Gram‐negative clinical isolates. N‐chlorotaurine (1%, 55 mmol l⁻¹) reduced the number of CFU of strains of methicillin‐resistant Staphylococcus aureus, linezolid‐resistant Staphylococcus epidermidis, vancomycin‐resistant, and linezolid‐ and vancomycin‐resistant Enterococcus faecium, 3MRGN and 4MRGN Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae by at least 2 log₁₀ steps after 15 min and completely or nearly to the detection limit after 30 min at pH 7·1 and 37°C.

Conclusion

The activity of NCT against these clinical isolates is similar to that against non‐resistant ATCC strains and therefore not influenced by antibiotic resistance. This can be explained by the oxidizing and chlorinating mechanism of action of NCT, which leads to an attack of multiple targets in the microorganisms.

Significance and Impact of the Study

The bactericidal spectrum of NCT is not restricted by resistance against antibiotics. Therefore, it can be used against resistant strains, too.

The antiseptic Miramistin: a review of its comparative in vitro and clinical activity

Miramistin is a topical antiseptic with broad antimicrobial action, including activity against biofilms and a clinical profile showing good tolerability. Miramistin was developed within a framework of the Soviet Union Cold War Space Program. It is available for clinical use in several prior Soviet bloc countries, but barely known outside of these countries and there is almost no mention of miramistin in the English literature. However, considering emerging antimicrobial resistance, the significant potential of miramistin justifies its re-evaluation for use in other geographical areas and conditions. The review consists of two parts: (i) a review of the existing literature on miramistin in English, Russian and Ukrainian languages; (ii) a summary of most commonly used antiseptics as comparators of miramistin. The oral LD50 was 1200 mg/kg, 1000 mg/kg and 100 g/L in rats, mice and fish, respectively. Based on the results of the review, we suggest possible applications of miramistin and potential benefits over currently used agents. Miramistin offers a novel, low toxicity antiseptic with many potential clinical uses that need better study which could address some of the negative impact of antimicrobial, antiseptic and disinfectant resistance.

Exposure of Aspergillus fumigatus to Atorvastatin Leads to Altered Membrane Permeability and Induction of an Oxidative Stress Response

Aspergillus fumigatus is a serious cause of disease in immune-deficient patients and in those with pulmonary malfunction (e.g., cystic fibrosis (CF), asthma). Atorvastatin is a member of the statin drug family, which are the main therapeutic agents used to decrease high serum cholesterol levels by inhibiting (HMG-CoA) reductase enzyme. The aim of the work presented here was to analyse the antifungal activity of atorvastatin and assess its effect on the virulence of A. fumigatus. Atorvastatin demonstrated strong antifungal activity and reduced the growth and viability of A. fumigatus. Exposure of A. fumigatus to atorvastatin led to a reduction in ergosterol content and increased membrane permeability, as evidenced by the release of protein, amino acids and gliotoxin. Proteomic analysis revealed an increased abundance of proteins associated with an oxidative stress response, such as the glutathione s-transferase family protein (+8.43-fold), heat shock protein Hsp30/Hsp42 (+2.02-fold) and 5-demethoxyubiquinone hydroxylase, mitochondrial (+1.73-fold), as well as secondary metabolites such as isocyanide synthase A icsA (+8.52-fold) and non-ribosomal peptide synthetase fmpE (+3.06-fold). The results presented here indicate that atorvastatin has strong antifungal properties and may have potential application in the treatment of A. fumigatus infections alone or in combination with existing antifungal agents.

Assessment of the in vitro and in vivo activity of atorvastatin against Candida albicans

Aim. The aim of this work was to characterize the response of Candida albicans to atorvastatin, and to assess its in vivo antifungal capability.Methodology. The effect of atorvastatin on the growth and viability of C. albicans was assessed. The ability of the statin to alter cell permeability was quantified by measuring amino acid and protein leakage. The response of C. albicans to atorvastatin was assessed using label-free quantitative proteomics. The in vivo antifungal activity of atorvastatin was assessed using Galleria mellonella larvae infected with C. albicans.Results. Atorvastatin inhibited the growth of C. albicans. The atorvastatin-treated cells showed lower ergosterol levels than the controls, demonstrated increased calcofluor staining and released elevated quantities of amino acids and protein. Larvae infected with C. albicans showed a survival rate of 18.1±4.2 % at 144 h. In contrast, larvae administered atorvastatin (9.09 mg kg^-1) displayed a survival rate of 60.2±6.4 % (P<0.05). Label-free quantitative proteomics identified 1575 proteins with 2 or more peptides and 465 proteins were differentially abundant (P<0.05). There was an increase in the abundance of enzymes with oxidoreductase and hydrolase activity in atorvastatin-treated cells, and squalene monooxygenase (4.52-fold increase) and lanosterol synthase (2.84-fold increase) were increased in abundance. Proteins such as small heat shock protein 21 (-6.33-fold) and glutathione peroxidase (-2.05-fold) were reduced in abundance.Conclusion. The results presented here indicate that atorvastatin inhibits the growth of C. albicans and is capable of increasing the survival of G. mellonella larvae infected with C. albicans.