Synthesis of a calix[4]arene derivative exposing multiple units of fucose and preliminary investigation as a potential broad-spectrum antibiofilm agent

Ventilator Acquired Pneumonia in COVID-19 ICU Patients: A Retrospective Cohort Study during Pandemia in France

Describe the characteristics of ventilation-acquired pneumonia (VAP) and potential risk factors in critically ill SARS-CoV-2 patients admitted in three French public hospitals during the first year of the COVID-19 pandemic. We conducted a monocentric retrospective study in seven Marseille intensive care units (ICUs) aiming to describe VAP characteristics and identify their risk factors. VAP patients were compared to a non-VAP control group. From March to November 2020, 161 patients admitted for viral-induced acute respiratory failure (ARF) requiring invasive mechanical ventilation (IMV) were included. This cohort was categorized in two groups according to the development or not of a VAP during their stay in ICU. 82 patients (51%) developed ventilation-acquired pneumonia. Most of them were men (77%) and 55% had hypertension. In the VAP population, 31 out of 82 patients (38%) had received dexamethasone and 47% were administered antibiotic course prior to ICU admission. An amount of 88% of respiratory infections were late VAPs with a median delay of 10 days from the onset of IMV. Gram negative bacteria were responsible for 62% of VAPs with Pseudomonas spp. being the most documented bacteria. Less than a third of the ICU-acquired infections were due to multidrug resistant (MDR) bacteria mainly displaying AmpC cephalosporin hyper production resistance phenotype. Multivariate analysis revealed that early Dexamethasone administration in ICU, male sex, older age and ROX score were risk factors for VAP whereas pre-ICU antimicrobial treatment and higher IGS 2 were protective factors. VAP is a frequent ICU-related complication affecting half of patients infected with SARS-CoV-2 and requiring IMV. It was responsible for increased morbidity due to a longer ICU and hospital stay. VAP risk factors included demographic factors such as age and sex. Dexamethasone was associated with a threefold greater risk of developing VAP during ICU stay. These results need to be comforted by large multi-centric studies before questioning the only available and effective treatment against SARS-CoV-2 in ICU patients.

Coxiella burnetii and Bartonella Endocarditis Diagnosed by Metagenomic Next-Generation Sequencing

(1) Background: Culture-negative endocarditis is challenging to diagnose. Here, we retrospectively identified 23 cases of Coxiella burnetii and Bartonella endocarditis by metagenomic next-generation sequencing. (2) Methods: Twenty-three patients with culture-negative endocarditis were retrospectively enrolled from Guangdong Provincial People's Hospital (n = 23) between April 2019 and December 2021. Metagenomic next-generation sequencing was performed on blood (n = 22) and excised cardiac valvular tissue samples (n = 22) for etiological identification, and Sanger sequencing was performed for pathogenic diagnostic verification. The demographic and clinical data of the 23 patients were obtained from hospital electronic health records. (3) Results: A total of 23 male patients (median age, 56 years (interquartile range, 16)) with culture-negative endocarditis were diagnosed with Coxiella burnetii (n = 21) or Bartonella (n = 2) species infection by metagenomic next-generation sequencing. All patients underwent cardiac surgery. The resected tissue exhibited both a significantly higher number of unique suspected pathogen read-pairs and more unique pathogen read-pairs than the blood specimens. The results of Sanger sequencing tests on all remaining tissue and blood specimens were positive. Oral doxycycline was added to the antibiotic regimen for at least 1.5 years according to etiology. A total of 21 patients (91%) were discharged, and 20 patients were healthy at the 21-month (interquartile range, 15) follow-up visit. One patient exhibited endocarditis relapse with the same pathogen from inadequate antibiotic administration. The last 2 patients (9%) developed septic shock and multiple organ dysfunction syndrome postoperatively and died shortly after discharge. (4) Conclusions: CNE caused by C. burnetii and Bartonella species is challenging to diagnose and exhibits poor outcome due to delayed treatment. In response, mNGS, characterized by high sensitivity and rapid results, is an effective alternative for the etiological identification of C. burnetii and Bartonella endocarditis.

Aryl-n-hexanamide linked enaminones of usnic acid as promising antimicrobial agents

Lichen secondary metabolites are well explored medicinal agents with diverse pharmacological properties. One of the important antibiotic lichen secondary metabolites is usnic acid. Its diverse medicinal profiles prompted us to explore it as a potential antitubercular molecule. Towards this direction, continuing our efforts on the discovery and development of new analogs with potent antitubercular properties we designed, synthesized, and evaluated a set of 37 usnic acid enaminone-coupled aryl-n-hexanamides (3-39). The study yielded a 3,4-dimethoxyphenyl compound (13, 5.3 µM) as the most active anti-TB molecule. The docking studies were performed on 7 different enzymes to better understand the binding modes, where it was observed that compound 13 bound strongly with glucose dehydrogenase (Gscore: - 9.03). Further antibacterial investigations revealed compound 2 with potent inhibition on Salmonella typhi and Bacillus subtilis (MIC 3 µM) and MIC values of 7 and 14 µM on Streptococcus mutans and Escherichia coli respectively. Compound 19 (3-F-5-CF₃-phenyl) displayed encouraging antibacterial profiles against E. coli, S. typhi and S. mutans with MIC values of 10 µM respectively. Interestingly, compound 20 (2,6-difluorophenyl) also displayed good antibacterial activity against E. coli with an MIC value of 6 µM. These encouraging pharmacological results will help for better designing and developing usnic acid-based semi-synthetic derivatives as potential antimicrobial agents. A set of 37 new usnic acid enaminone-coupled aryl-n-hexanamides were synthesized and evaluated as potential antimicrobial agents. Compound 13 was identified as the most active antitubercular molecule. 13 was further docked against 7 different enzymes of tuberculosis. The molecule displayed maximum binding energy with the enzyme Glucose dehydrogenase (Gscore: - 9.03), indicating that these hexanamides possibly act by inhibiting the glucose metabolic pathway of the bacterium. Surprisingly, the intermediate hexanoic acid 2 was identified as potent antibacterial agent, acting on both gram-positive and gram-negative bacterial strains (3-14 μM). The active compounds may be subjected to structural iterations to develop further leads.

Pillar[5]arene-Based Polycationic Glyco[2]rotaxanes Designed as Pseudomonas aeruginosa Antibiofilm Agents

Pseudomonas aeruginosa (P.A.) is a human pathogen belonging to the top priorities for the discovery of new therapeutic solutions. Its propensity to generate biofilms strongly complicates the treatments required to cure P.A. infections. Herein, we describe the synthesis of a series of novel rotaxanes composed of a central galactosylated pillar[5]arene, a tetrafucosylated dendron, and a tetraguanidinium subunit. Besides the high affinity of the final glycorotaxanes for the two P.A. lectins LecA and LecB, potent inhibition levels of biofilm growth were evidenced, showing that their three subunits work synergistically. An antibiofilm assay using a double ΔlecAΔlecB mutant compared to the wild type demonstrated that the antibiofilm activity of the best glycorotaxane is lectin-mediated. Such antibiofilm potency had rarely been reached in the literature. Importantly, none of the final rotaxanes was bactericidal, showing that their antibiofilm activity does not depend on bacteria killing, which is a rare feature for antibiofilm agents.

Modified Galacto- or Fuco-Clusters Exploiting the Siderophore Pathway to Inhibit the LecA- or LecB-Associated Virulence of Pseudomonas aeruginosa

Galacto- and fuco-clusters conjugated with one to three catechol or hydroxamate motifs were synthesised to target LecA and LecB lectins of Pseudomonas aeruginosa (PA) localised in the outer membrane and inside the bacterium. The resulting glycocluster-pseudosiderophore conjugates were evaluated as Trojan horses to cross the outer membrane of PA by iron transport. The data suggest that glycoclusters with catechol moieties are able to hijack the iron transport, whereas those with hydroxamates showed strong nonspecific interactions. Mono- and tricatechol galactoclusters (G1C and G3C) were evaluated as inhibitors of infection by PA in comparison with the free galactocluster (G0). All of them exhibited an inhibitory effect between 46 to 75 % at 100 μM, with a higher potency than G0. This result shows that LecA localised in the outer membrane of PA is involved in the infection mechanism.

Antimicrobial Activity of Calixarenes and Related Macrocycles

Calixarenes and related macrocycles have been shown to have antimicrobial effects since the 1950s. This review highlights the antimicrobial properties of almost 200 calixarenes, resorcinarenes, and pillararenes acting as prodrugs, drug delivery agents, and inhibitors of biofilm formation. A particularly important development in recent years has been the use of macrocycles with substituents terminating in sugars as biofilm inhibitors through their interactions with lectins. Although many examples exist where calixarenes encapsulate, or incorporate, antimicrobial drugs, one of the main factors to emerge is the ability of functionalized macrocycles to engage in multivalent interactions with proteins, and thus inhibit cellular aggregation.

Synthesis of N-acetylglucosamine and N-acetylallosamine resorcinarene-based multivalent β-thio-glycoclusters: unexpected affinity of N-acetylallosamine ligands towards Wheat Germ Agglutinin

Herein, we report the synthesis of calix[4]resorcinarene-based multivalent ligands bearing β-S-GlcNAc and β-S-AllNAc recognition elements. A clickable β-S-AllNAc derivative was successfully prepared from a β-thioalkynyl GlcNAc precursor, making use of a 2,3-oxazoline intermediate, easily formed by intramolecular displacement of a triflate group located at the 3-position by the 2-N-acetate group. By reaction of these alkynyl-functionalized derivatives with an octaazido-calix[4]resorcinarene macrocycle having undecyl chains, two octavalent glycoclusters exposing the epimeric N-acetylhexosamines were obtained. In addition, a related calix[4]resorcinarene-based glycocluster having methyl groups instead of undecyl chains and β-S-GlcNAc residues was also synthesized. After an initial evaluation of the interaction of the undecyl-functionalized β-S-GlcNAc octavalent derivative with Wheat Germ Agglutinin (WGA) by a turbidimetry experiment, the interaction of the three synthesized glycoclusters towards WGA was studied by Isothermal Titration Calorimetry. The results showed a favorable effect due to the presence of the undecyl chains in terms of affinity. Surprisingly, the β-S-AllNAc octavalent compound showed the highest affinity among the evaluated glycoclusters, showing for the first time that WGA interacts with β-AllNAc-bearing ligands. Molecular docking studies of β-AllNAc with WGA in comparison with β-GlcNAc contributed to the understanding of the atomic interactions responsible for this unexpected affinity.