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International audience; Objectives: Rubella cases in the Central African Republic (CAF) are currently identified during measles surveillance. This study aimed to investigate rubella epidemiology between 2015 and 2016 and to provide baseline genotype data for monitoring future rubella control efforts.Methods: 831 measles IgM negative or equivocal sera from 2015/2016 were tested for rubella IgM antibodies and 350 rubella IgM positive sera collected between 2008 and 2016 were selected for PCR and sequencing.Results: 411 of the 831 sera (49.5%) were rubella IgM positive and most cases (n=391, 95.1%) occurred between January and April. Most patients were between 5 and 9 years old (50.2%) and more than half of the rubella cases (56.7%) originated from the capital Bangui. Genotype information was obtained for 37 of the 350 selected rubella IgM-positive specimens, with the majority of the patients originating from Bangui (n=24, 64.9%) and sequences covering all years except 2009. Phylogenetic analysis identified genotypes 1E (n=12), 1G (n=5) and 2B (n=20), with 2B being detected from 2014 onwards.Conclusions: Our study confirmed the important role of rubella as a rash and fever disease in CAF and provided comprehensive data on rubella epidemiology and the first information on rubella genotypes in the country.Keywords: Central African Republic; epidemiology; genotype; rash; rubella virus; surveillance.

The popular use of Pterocarpus erinaceus as antimicrobial prompted us to study the antifungal properties of its bark, leaves and roots against Candida albicans, Aspergillus fumigatus, and Aspergillus niger. Thus, the broth microdilution method was used to perform the test and only the root extract showed significant antifungal activity against A. fumigatus with value at MIC 16 μg/mL. This root extract was further partitioned by immiscible liquid-liquid extraction into five fractions. Successive chromatographic columns were used for the purification of the organic fractions which led to the isolation and the identification of five compounds including two new (3 and 5) and three known (1, 2, and 4). Their structures were established as muningin 1, the mixture of formononetin and pseudobaptigenin 2, boutotone 3, isoliquiritigenin 4, and boutomycone 5, by the mean of spectroscopic data compared to those reported in the literature. Compounds 1-5 were also tested on A. fumigatus against which 1, 2, and 5 showed antifungal effects with MIC values at 853.3, 28.7, and 452.3 μM, respectively. The obtained results indicated that the traditional use of this plant as antimicrobial could be related to its roots.

The four possible conformers of a new tetrakisguanidino calix[4]arene thought to interact deleteriously with bacterial membranes have been synthesized, characterized, and evaluated for their in vitro cytotoxicity and antibacterial activity against various reference Gram-negative and Gram-positive bacteria, as well as Mycobacterium tuberculosis. It appears that reversal of at least one phenolic unit results in clear increases in their activities. This can be attributed to the evolution towards bolaform structures, which are able to interact more deeply with the bacterial membrane. Indeed, the 1,3-alternate conformer 16 exhibits the best antibacterial activity (MIC

International audience; Les compétences sociales se travaillent tout au long de la vie et doivent s'apprendre au plus tôt car elles sont indispensables dans la vie professionnelle. La coopération notamment est une compétence essentielle dans une entreprise et c'est pour cela qu'elle est utilisée comme moyen pédagogique dans la formation proposée par les deux programmes Initiatives d'Excellences en Formations Innovantes (IDEFI). Ceux-ci se sont associés pour proposer aux étudiants en L2 Sciences pour la Santé de l'Université de Lorraine de « booster leur réussite » par le développement des compétences sociales. Grâce à une semaine de formation basée sur la coopération, les étudiants ont pu travailler leurs compétences sociales et augmenter leur confiance en eux.

Multidrug-resistant (MDR) bacteria constitute a global health issue. Over the past ten years, interest in nanoparticles, particularly metallic ones, has grown as potential antibacterial candidates. However, as there is no consensus about the procedure to characterize the metallic nanoparticles (MNPs, i.e., metallic aggregates) and evaluate their antibacterial activity, it is impossible to conclude about their real effectiveness as a new antibacterial agent. To give part of the answer to this question, 12 nm gold and silver nanoparticles have been prepared by a chemical approach. After their characterization by transmission electronic microscopy (TEM), Dynamic Light Scattering (DLS), and UltraViolet-visible (UV-vis) spectroscopy, their surface accessibility was tested through the catalytic reduction of the 4-nitrophenol, and their stability in bacterial culture medium was studied. Finally, the antibacterial activities of 12 nm gold and silver nanoparticles facing Staphylococcus aureus and Escherichia coli have been evaluated using the broth microdilution method. The results show that gold nanoparticles have a weak antibacterial activity (i.e., slight inhibition of bacterial growth) against the two bacteria tested. In contrast, silver nanoparticles have no activity on S. aureus but demonstrate a high antibacterial activity against Escherichia coli, with a minimum inhibitory concentration of 128 µmol/L. This high antibacterial activity is also maintained against two MDR-E. coli strains.

Treatment of kidney stones is based on symptomatic medications which are associated with side effects such as gastrointestinal symptoms (e.g., nausea, vomiting) and hepatotoxicity. The search for effective plant extracts without the above side effects has demonstrated the involvement of antioxidants in the treatment of kidney stones. A local survey in Morocco has previously revealed the frequent use of Rubia tinctorum L. (RT) for the treatment of kidney stones. In this study, we first explored whether RT ethanolic (E-RT) and ethyl acetate (EA-RT) extracts of Rubia tinctorum L. could prevent the occurrence of urolithiasis in an experimental 0.75% ethylene glycol (EG) and 2% ammonium chloride (AC)-induced rat model. Secondly, we determined the potential antioxidant potency as well as the polyphenol composition of these extracts. An EG/AC regimen for 10 days induced the formation of bipyramid-shaped calcium oxalate crystals in the urine. Concomitantly, serum and urinary creatinine, urea, uric acid, phosphorus, calcium, sodium, potassium, and chloride were altered. The co-administration of both RT extracts prevented alterations in all these parameters. In the EG/AC-induced rat model, the antioxidants- and polyphenols-rich E-RT and EA-RT extracts significantly reduced the presence of calcium oxalate in the urine, and prevented serum and urinary biochemical alterations together with kidney tissue damage associated with urolithiasis. Moreover, we demonstrated that the beneficial preventive effects of E-RT co-administration were more pronounced than those obtained with EA-RT. The superiority of E-RT was associated with its more potent antioxidant effect, due to its high content in polyphenols.

Phenolamides constitute a family of metabolites, widely represented in the plant kingdom, that can be found in all plant organs with a predominance in flowers and pollen grains. They represent a large and structurally diverse family, resulting from the association of phenolic acids with aliphatic or aromatic amines. Initially revealed as active compounds in several medicinal plant extracts, phenolamides have been extensively studied for their health-promoting and pharmacological properties. Indeed, phenolamides have been shown to exhibit antioxidant, anti-inflammatory, anti-cancer and antimicrobial properties, but also protective effects against metabolic syndrome and neurodegenerative diseases. The purpose of this review is to summarise this large body of literature, including in vitro and in vivo studies, by describing the diversity of their biological properties and our actual knowledge of the molecular mechanisms behind them. With regard to their considerable pharmacological interest, the question of industrial production is also tackled through chemical and biological syntheses in engineered microorganisms. The diversity of biological activities already described, together with the active discovery of the broad structural diversity of this metabolite family, make phenolamides a promising source of new active compounds on which future studies should be focused.

Lactobacillus rhamnosus GG (LGG) was encapsulated in core–shell alginate–silica microcapsules by coating the electrosprayed ionogel with a silica shell via hydrolysis/condensation of alkoxysilane precursors. The viability of encapsulated LGG highly depends on the mineralisation conditions (in aqueous or organic phases), identified as a critical step. More importantly, due to the unswelling of silica and to its mesoporosity that allows nutriment-metabolite diffusion, it was possible to avoid cell leakage and additionally insure bacterial growth inside the microcapsules. The results of this work gave a proof-of-concept for controlled bacterial proliferation in microcompartments, which have straightforward applications in oral delivery of probiotics.

International audience; 4-Benzoyl-3,5-diaryltetrahydrofuran-2,2-dicarbonitriles were first synthesized from 2,2-dicyano-3-aryloxiranes and chalcones at toluene reflux; the 4,5-cis products proved to be predominantly formed and were isolated. Whereas shortened reaction times were observed by using microwave irradiation or catalytic cuprous chloride, no significant stereoselectivity change was in general noticed. Reacting 2,2-dicyano-3-aryloxiranes with 2-cyclopentenone next afforded 3-aryl-4-oxohexahydro-1H-cyclopenta[c]furan-1,1-dicarbonitriles, and the endo stereoisomers were isolated. That no stereoselectivity change was noticed in the presence of cuprous chloride rather suggests an impact of the salt on the epoxide ring opening. Finally, treatment of 2,2-dicyano-3-aryloxiranes by 2-morpholinoacrylonitrile yielded 3-cyano-3-morpholino-5-phenyltetrahydrofuran-2,2-dicarbonitriles from which the preponderant trans isomers were isolated. Importantly, the molecular mechanism of the domino reaction between 2,2-dicyano-3-phenyloxirane and 2-cyclopentenone was studied. The rate-determining thermal ring opening of the oxirane is followed by a non-concerted pseudoradical-type reaction of the carbonyl ylide with 2-cyclopentenone. Using the bond evolution theory also allowed the regioselectivity of this non-polar reaction to be explained.

The investigation of natural products used in Traditional Medicine in Africa is complicated as modern analytical and screening methods are often not available. Computer aided product identification from traditional usage records (CAPITURE) may provide an interesting alternative and has been evaluated in the context of an ethnobotanical survey on fungal diseases and their traditional treatment in Tchamba District (Togo). 53 traditional healers were interviewed and their knowledge recorded. Several indicators, the Use Value (UV), Plant Part Value (PPV), Specific Use (SU) Value, Intraspecific Use Value (IUV) and Informant Consensus Factor (ICF), were applied to the data. Those indices, in addition to a bibliographic review, were then fed into a computer-aided approach which predicted two interesting plants out of the 43 species survey-recorded and their specific activities: Pterocarpus erinaceus sap against ringworm, Daniellia oliveri sap against intertrigo and respectively their roots and trunk barks against candidiasis. Subsequent laboratory-based studies have confirmed the predicted antimicrobial activities with MIC (128 μg/mL to 30 mg/mL) and without any notable toxicity on a normal human cell (MRC-5 cells). Although such a method may not be flawless, it is able to provide first leads, and in the face of limited resources, is an attractive alternative worth considering.

International audience; Original 1-amino substituted thioxanthone derivatives were easily prepared from the bare heterocycle by a deprotometalation-iodolysis-copper-catalyzed CeN bond formation sequence. This last reaction delivered mono-or/and diarylated products depending on the aniline involved. 1-Amino-9-thioxanthone was also prepared and reacted with 2-iodoheterocycles. Interestingly, while 1-(arylamino)-9-thioxanthones could be isolated, their subsequent cyclization was found to deliver original hexacyclic derivatives of helicoidal nature. Evaluation of their photophysical properties revealed high fluorescence in polar media, indicating potential applications for biological imaging. These compounds being able to inhibit PIM1 kinase, their putative binding mode was examined through molecular modeling experiments. Altogether, these results tend to suggest the discovery of a new family of fluorescent PIM inhibitors and pave the way for their future rational optimization.

High concentrations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome have been described in wastewater and sewage sludge. It raises the question of the security of land sludge disposal practices during a pandemic. This study aimed to compare SARS-CoV-2's resistance to the main inactivating factors in sludge treatments, pH and heat, to that of native wastewater somatic coliphages. The latest can be easily used as an indicator of treatment efficiency in the field. The effects of heat treatment and pH on the survival of SARS-CoV-2 and somatic coliphages were investigated in simple media. The T90 value (time required for a 90% reduction in the virus or a 1 × log10 decline) at 50 °C was about 4 min for infectious SARS-CoV-2, and around 133 min for infectious somatic coliphages, with no decrease in SARS-CoV-2 genome. For infectious SARS-CoV-2, a slight decrease (4 log10) can be considered efficient treatments for infectious SARS-CoV-2. We concluded that somatic coliphages can be considered highly conservative and easy to use indicators of the inactivation of SARS-CoV-2 during treatments based on heat and alkaline pH., Graphical abstract Unlabelled Image

International audience; Given the worldwide spread of bacterial drug resistance, there is an urgent need to develop new compounds that exhibit potent antibacterial activity and that are unimpaired by this phenomenon. Quaternary ammonium compounds have been used for many years as disinfectants, but recent advances have shown that polycationic derivatives exhibit much stronger activity and are less prone to bacterial resistance than commonly used monocationic compounds. In this sense, we prepared three series of new bis‐cationic compounds: bis‐thiazoliums, bis‐imidazoliums, and bis‐1,2,4‐triazoliums. If some compounds of the first series showed fair antibacterial activity, most of those belonging to the two other series were highly potent, with minimum inhibitory concentrations close to 1 μg mL−1. Some of them also exhibited low toxicity toward eukaryotic MRC‐5 lung fibroblasts, and we showed that this toxicity is clearly correlated with clogP. Finally, four selected compounds were found to exhibit a clear bactericidal effect.

International audience; Leaves and fruits of Indigofera caerulea, an endemic plant from Djibouti, are used in the traditional medicine to treat infectious diseases. However, there are no documented scientific reports on phytochemistry and antimicrobial properties of the fruit of this species. For the first time, the chemical compounds and the evaluation of the antimicrobial and antioxidant properties of Indigofera caerulea Rox fruits were investigated. The hexane and methanolic extracts showed a significant activity against both Staphylococcus aureus with a Minimal Inhibitory Concentration (MIC) of 256 and 128 μg/mL, respectively, and Enterococcus faecalis with a MIC of 128 μg/mL for the two extracts. The methanolic and acetone extracts showed effective free radical scavenging activities in 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays, while only the methanolic extract revealed the best ferric-reducing/antioxidant power (FRAP). The highest amount of both total polyphenolic content and total flavonoid content were detected in the methanolic extract (818.14 mg gallic acid equivalents (GAE)/g and 102.10 mg quercetin equivalents (QE)/g, respectively). About the phytochemistry of this extract, two phenolic compounds and three flavonoids were identified rapidly by HPTLC-MS, confirmed by NMR and quantified. Also, chlorogenic acid, caffeic acid and benzoic acid were identified by HPLC. Methyl gallate, the major compound isolated from the methanolic extract, showed antibacterial activity against S. aureus (MIC: 64 μg/mL). Twelve compounds were identified in hexane extract where fatty acids comprised 95.1% and steroids 3.5%. Thus, I. caerulea fruits could serve as a bio-based material for antioxidants and antibacterial compounds.

With the emergence of antibiotic resistance, the interest for antimicrobial agents has recently increased again in public health. Copper was recognized in 2008 by the United States Environmental Protection Agency (EPA) as the first metallic antimicrobial agent. This led to many investigations of the various properties of copper as an antibacterial, antifungal and antiviral agent. This review summarizes the latest findings about 'contact killing', the mechanism of action of copper nanoparticles and the different ways micro-organisms develop resistance to copper.

International audience; Nanotechnology has been revealed as a fundamental approach for antibiotics delivery. In this paper, recent findings demonstrating the superiority of nanocarried-antibiotics over "naked" ones and the ways by which nanoparticles can help to overwhelm bacterial drug resistance are reviewed. The second part of this paper sheds light on nanoparticle-bacterium interaction patterns. Finally, key factors affecting the effectiveness of nanoparticles interactions with bacteria are discussed.

International audience; It has been shown that diverse strains of bacteria can be separated according to their characteristic surface properties by means of CE. We employed here this analytical technique to the study of colistin-resistance in Gram-negative bacteria, which involves the selection of mutants with modified outer membrane composition resulting in changes of surface cell properties. In the same way as with molecular entities, we performed firstly the validation of an ITP-based CE method for three common pathogenic Gram-negative bacteria namely Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Secondly, we compared the electrophoretic profiles of bacterial samples from a colistin-susceptible clinical isolate of K. pneumoniae and from the corresponding colistin-resistant derivative. By a simple CE run taking a few minutes, the coexistence of several bacterial subpopulations in the colistin-resistant derivative was clearly evidenced. This work encourages further research that would allow applications of CE in clinical laboratory for a daily monitoring of bacterial population in cared patients when "last-chance" colistin treatment is initiated against multidrug-resistant bacteria.

International audience; A total of 125 Streptomyces strains were isolated from an Algerian wetland (Fetzara Lake) and characterized by growth on different culture media.Phylogenetic analyses were carried out by 16S rRNA sequence comparison after PCR amplification using universal primers. Antibacterial bioassays performed by the agar diffusion method enabled us to retain 33 Streptomyces isolates for their activity against two Gram-positive bacteria (Bacillus subtilis and Micrococcus luteus) and one Gram-negative bacteria (Escherichia coli).Among them, six isolates inhibited all three indicator strains. Antibacterial compounds were then extracted from the solid culture media with ethanol and ethyl acetate as organic solvents. The minimal inhibitory concentration (% v/v) of the extracts was evaluated by a standardized broth dilution method against different clinical-resistant bacterial isolates and Candida albicans.The most active crude extracts were selected for further characterization by chromatographic analysis (RP-HPLC).; Cent vingt-cinq souches de Streptomyces ont été collectées dans une région humide d’Algérie (lac Fetzara) et caractérisées par leur croissance sur différents milieux.Des analyses phylogénétiques ont été réalisées sur la collection à partir de la séquence codant l’ARN 16S après amplification PCR avec des amorces universelles.Des tests d’activités antibactériennes par la méthode de diffusion en agar ont permis de retenir 33 souches pour leurs activités contre deux bactéries à Gram positif (Bacillus subtilis et Micrococcus luteus) et une à Gram négatif (Escherichia coli). Parmi ces souches, six inhibent la croissance des trois souches indicatrices. Les molécules responsables des activités antibactériennes observées ont été extraites du milieu de croissance solide avec des solvants organiques comme l’éthanol et l’acétate d’éthyle. La concentration minimale inhibitrice (% v/v) des extraits a été évaluée par la méthode standardisée de dilution en milieu liquide contre différents isolats bactériens cliniques résistants et contre Candida albicans. Les extraits les plus actifs ont été analysés par chromatographie haute pression (RP-HPLC).

International audience; Antimicrobial molecules have been used for more than 50 years now and are the basis of modern medicine. No surgery can nowdays be imagined to be performed without antibiotics; dreadful diseases like tuberculosis, leprosis, siphilys, and more broadly all microbial induced diseases, can be cured only through the use of antimicrobial treatments. However, the situation is becoming more and more complex because of the ability of microbes to adapt, develop, acquire, and share mechanisms of resistance to antimicrobial agents. We choose to introduce this review by briefly drawing the panorama of antimicrobial discovery and development, but also of the emergence of microbial resistance. Then we describe how Atomic Force Microscopy (AFM) can be used to provide a better understanding of the mechanisms of action of these drugs at the nanoscale level on microbial interfaces. In this section, we will address these questions: (1) how does drug treatment affect the morphology of single microbes?; (2) do antimicrobial molecules modify the nanomechanical properties of microbes, or do the nanomechanical properties of microbes play a role in antimicrobial activity and efficiency?; and (3) how are the adhesive abilitites of microbes affected by antimicrobial drugs treatment? Finally, in a second part of this review we focus on recent studies aimed at changing the paradigm of the single molecule/cell technology that AFM typically represents. Recent work dealing with the creation of a microbe array which can be explored by AFM will be presented, as these developments constitute the first steps toward transforming AFM into a higher throughput technology. We also discuss papers using AFM as NanoMechnanicalSensors (NEMS), and demonstrate the interest of such approaches in clinical microbiology to detect quickly and with high accuracy microbial resistance.

International audience

Ethnopharmacological relevance Pterocarpus erinaceus has been chosen based on ethnobotanical surveys carried out in the Tchamba district of the Republic of Togo. Aim of the study Investigation of the antibacterial as well as cytotoxic activities of whole extracts, fractions and compounds isolated from the leaves, trunk bark and roots of Pterocarpus erinaceus. Materials and methods Bio-guided fractionation of the raw extracts of plant parts and subsequent isolation of compounds from active fractions using normal phase open column chromatography. The broth microdilution method was used to evaluate the antibacterial activity, based on the determination of Minimal Inhibitory Concentrations (MICs) against several bacterial species representative of the most commonly encountered infectious diseases worldwide. The cytotoxicity of the raw extract and the most active fractions on a human non-cancerous cell (namely MRC-5) was estimated with a MTT assay. The chemical structure of the compounds isolated was elucidated using a combination of advanced Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS). Results All extracts and fractions tested have shown good activities against Gram-positive bacteria (including Methicillin-Resistant Staphylococcus aureus, MRSA) and against Pseudomonas aeruginosa with MIC values ranging from 32 µg/mL to 256 µg/mL. In contrast, extracts were not toxic to MRC-5 cells. Four compounds have been isolated: Compound 1 (friedeline); Compound 2 (2,3 dihydroxypropyloctacosanoate); Compound 3 (a mixture of β-sitosterol, stigmasterol and campesterol); Compound 4 (β-sitosteryl-β-D-glucopyranoside) and shown to be active against some of the bacteria tested. They were active with MIC equal to 4 µg/mL against strains of S. aureus (including MRSA). To the best of our knowledge, all of them except friedeline have never been reported in this plant species. Conclusion P. erinaceus is confirmed as a plant harboring promising antibacterial activity with activities against serious human pathogens at very low concentrations. Some of the compounds isolated are also active at concentrations as low as 4 µg/mL and therefore, may provide new leads for the development of antibacterial agents.

Single-molecule force spectroscopy using atomic force microscopy (AFM) is more and more used to detect and map receptors, enzymes, adhesins, or any other molecules at the surface of living cells. To be specific, this technique requires antibodies or ligands covalently attached to the AFM tip that can specifically interact with the protein of interest. Unfortunately, specific antibodies are usually lacking (low affinity and specificity) or are expensive to produce (monoclonal antibodies). An alternative strategy is to tag the protein of interest with a peptide that can be recognized with high specificity and affinity with commercially available antibodies. In this context, we chose to work with the human influenza hemagglutinin (HA) tag (YPYDVPDYA) and labeled two proteins: covalently linked cell wall protein 12 (Ccw12) involved in cell wall remodeling in the yeast Saccharomyces cerevisiae and the β2-adrenergic receptor (β2-AR), a G protein-coupled receptor (GPCR) in higher eukaryotes. We first described the interaction between HA antibodies, immobilized on AFM tips, and HA epitopes, immobilized on epoxy glass slides. Using our system, we then investigated the distribution of Ccw12 proteins over the cell surface of the yeast S. cerevisiae. We were able to find the tagged protein on the surface of mating yeasts, at the tip of the mating projections. Finally, we could unfold multimers of β2-AR from the membrane of living transfected chinese hamster ovary cells. This result is in agreement with GPCR oligomerization in living cell membranes and opens the door to the study of the influence of GPCR ligands on the oligomerization process.

Saccharomyces cerevisiae and Candida albicans are model yeasts for biotechnology and human health, respectively. We used atomic force microscopy (AFM) to explore the effects of caspofungin, an antifungal drug used in hospitals, on these two species. Our nanoscale investigation revealed similar, but also different, behaviors of the two yeasts in response to treatment with the drug. While administration of caspofungin induced deep cell wall remodeling in both yeast species, as evidenced by a dramatic increase in chitin and decrease in β-glucan content, changes in cell wall composition were more pronounced with C. albicans cells. Notably, the increase of chitin was proportional to the increase in the caspofungin dose. In addition, the Young modulus of the cell was three times lower for C. albicans cells than for S. cerevisiae cells and increased proportionally with the increase of chitin, suggesting differences in the molecular organization of the cell wall between the two yeast species. Also, at a low dose of caspofungin (i.e., 0.5× MIC), the cell surface of C. albicans exhibited a morphology that was reminiscent of cells expressing adhesion proteins. Interestingly, this morphology was lost at high doses of the drug (i.e., 4× MIC). However, the treatment of S. cerevisiae cells with high doses of caspofungin resulted in impairment of cytokinesis. Altogether, the use of AFM for investigating the effects of antifungal drugs is relevant in nanomedicine, as it should help in understanding their mechanisms of action on fungal cells, as well as unraveling unexpected effects on cell division and fungal adhesion.

International audience; Structural and mechanical mapping at the nanoscale by novel high-speed multiparametric Quantitative Imaging (QI) and PeakForce Quantitative Nanomechanical Mapping (PF-QNM) AFM modes was compared to the classical Force Volume (FV) mapping for the case of living Pseudomonas aeruginosa bacterial cells. QI and PF-QNM modes give results consistent with FV for the whole cells in terms of morphology and elastic modulus, while providing higher resolution and shorter acquisition time. As an important complement, the influence of scanning parameters on elastic modulus values was explored for small 0.2(2) mu m(2) central area on top of cells. The modulus decreases with the indentation depth due to the effect of the hard cell wall, while it increases vs. tip oscillation frequency, displaying viscoelastic behaviour of the living bacterial cells. The ability of different AFM modes to follow correctly the bacteria viscoelastic behaviour at high oscillation frequency was tested.

Summary Cyclodextrins (CyDs) currently displays even today the image of a natural macrocyclic compound largely dominant in the formation of inclusion complexes with small hydrophobic molecules. During the past 10 years, advances in this field allowed to achieve more and more sophisticated CyDs derivatives opening a simple access in scale-up quantities to original and better CyD-based gene delivery systems. In addition, possibility to combine covalent and supramolecular approaches offers new venues for the design of tailor-made CyD-based nanovehicles to improve their transfection ability and gene transfer in cells. In this account, we describe our recent progress in the construction of a novel CyD-based G0 (generation number) core dendrimer, scalable to CyD oligomers by a strategy using protonable guanidine tethers and whose concept can be generalized for the assembly of CyD pre-coated dendrimers. The synthetic strategy based on an original Staudinger-Aza-Wittig tandem coupling reaction. We present an outline of the different analytical strategies to characterize CyD-ODN (cyclodextrin-oligodeoxynucleotide) complexes. Among them, Capillary electrophoresis (CE) was used to perfectly characterize our CyD-siRNA and CyD-DNA complexes and shown to be a very attractive method with advantages of low sample consumption, rapid analysis speed, and high efficiency that make this technology a major tool for association constant measurement. Finally, we present the different biological methods that can be used, in vitro, to study gene delivery, and more precisely ones we have performed to evaluate the capability of our original model bis-guanidinium-tetrakis-β-cyclodextrin dendrimeric tetrapod, to deliver efficiently DNA or siRNA in eukaryotic cells.

Colistin resistance, although uncommon, is increasingly being reported among Gram-negative clinical pathogens, and an understanding of its impact on the activity of antimicrobials is now evolving. We evaluated the potential for synergy of colistin plus trimethoprim, trimethoprim-sulfamethoxazole (1/19 ratio), or vancomycin against 12 isolates of Acinetobacter baumannii ( n = 4), Pseudomonas aeruginosa ( n = 4), and Klebsiella pneumoniae ( n = 4). The strains included six multidrug-resistant clinical isolates, K. pneumoniae ATCC 700603, A. baumannii ATCC 19606, P. aeruginosa ATCC 27853, and their colistin-resistant derivatives (KPm1, ABm1, and PAm1, respectively). Antimicrobial susceptibilities were assessed by broth microdilution and population analysis profiles. The potential for synergy of colistin combinations was evaluated using a checkerboard assay, as well as static time-kill experiments at 0.5× and 0.25× MIC. The MIC ranges of vancomycin, trimethoprim, and trimethoprim-sulfamethoxazole (1/19) were ≥128, 4 to ≥128, and 2/38 to >128/2,432 μg/ml, respectively. Colistin resistance demonstrated little impact on vancomycin, trimethoprim, or trimethoprim-sulfamethoxazole MIC values. Isolates with subpopulations heterogeneously resistant to colistin were observed to various degrees in all tested isolates. In time-kill assays, all tested combinations were synergistic against KPm1 at 0.25× MIC and 0.5× MIC and ABm1 and PAm1 at 0.5× MIC. In contrast, none of the tested combinations demonstrated synergy against any colistin-susceptible P. aeruginosa isolates and clinical strains of K. pneumoniae isolates. Only colistin plus trimethoprim or trimethoprim-sulfamethoxazole was synergistic and bactericidal at 0.5× MIC against K. pneumoniae ATCC 700603. Colistin resistance seems to promote the in vitro activity of unconventional colistin combinations. Additional experiments are warranted to understand the clinical significance of these observations.

Fluorinated compounds are not only more hydrophobic than their hydrogenated counterparts but also oleophobic. This makes them interesting for biomedical applications. They form a large variety of supramolecular architectures and, if appropriately designed, they spontaneously form vesicles. Herein we report the synthesis of novel monocatenar fluorinated surfactant, named F 9 NH(EO) 2 NH 2 , its use as ss DNA vector with potential applications in gene delivery or RNA interference. The molecular structure of the amphiphilic compound was designed in three parts: (i) a fluorinated hydrophobic tag responsible of self-assembling, (ii) a flexible and hydrophilic ethylenoxide moiety as polar head and (iii) a protonated at physiological pH primary amine responsible of binding. Surface tension, dynamic light scattering (DLS) measurements, and TEM studies showed that the monocatenar surfactant F 9 NH(EO) 2 NH 2 spontaneously self-assembles into vesicles. This represents another example in addition to the few existing in the literature and it highlights the unique properties of the fluorinated tail. Interactions between ss DNA and cationic monocharged F 9 NH(EO) 2 NH 2 were probed by static light scattering (SLS), fluorescence and circular dichroism (CD). F 9 NH(EO) 2 NH 2 was found to exclude ethidium bromide (EB) from ss DNA/EB complex, and this process was dependent on the ss DNA concentration and on the charge ratio surfactant to ss DNA. CD spectra showed that by increasing the surfactant concentration, ss DNA undergoes a continuous conformational transition from native B-form to a more ordered phase (Z + /Z − ≤ 3) and then to a less ordered phase (Z + /Z − ≥ 4), which confirmed the results obtained by fluorimetry and SLS measurements. Cell viability studies reveled that monocatenar fluorinated surfactant F 9 NH(EO) 2 NH 2 is not toxic for human cells (MRC-5) below 40 μM.

Graphical abstract, Two well-known antibiotic heterocycles, the ‘quinolone’ nalidixic acid and the β-lactam penicillin V, active at different levels of the bacterial growth process, have been attached via an ether–ester junction to the p-tert-butylcalix[4]arene lower rim, in alternate position. The resulting hydrophobic molecular drug-organisers were fully characterized, and evaluated over two Gram negative and three Gram positive reference strains, using disk diffusion assays with disks impregnated with solution of title compound in pure DMSO. An interesting activity was observed over Staphylococcus aureus ATCC 25923 with the dissymmetrical podand incorporating one penicillin and one nalidixic ester moieties.

International audience; Hydroxy pentacyclic triterpenoic acids (HPTAs) have been described to exhibit numerous pharmacological properties. They also exhibit poor hydrosolubility, thus affecting their potential clinical interest. The association of these active substances with cyclodextrins could be employed to improve some properties such as bioavailability and activity. 1:1 Inclusion complexes of ursolic, oleanolic and betulinic acids with γ-cyclodextrin were evaluated by DSC and 1H NMR spectroscopy. The apparent formation constants (Kf) of the formed complexes were determined using RP-HPLC. Thermodynamic parameters ΔGº, ΔHº and ΔSº were calculated with temperatures ranging from 25 to 45 °C to evaluate the complexation process. Finally the influence of γ-CD on the HPTA water solubility was investigated by phase-solubility studies.

Two new anthraquinone glycosides: methyl 8-hydroxy-4,7-dimethoxy-1-methyl-9,10-dioxo-3-(beta-d-glucopyranosyloxy)-9,10-dihydroanthracene-2-carboxylate (1) and methyl 3-methoxy-1-methyl-9, 10-dioxo-8-(beta-d-glucopyranosyloxy)-9,10-dihydroanthracene-2-carboxylate (2), have been isolated from the methanolic extract of Gladiolus segetum. Their structures were established based on spectroscopic analyses. The fraction containing anthraquinones was evaluated against MRC-5 cell lines and was found to be 82% cytotoxic at 1 mg mL−1.

Facing the lack in specific antiviral treatment, it is necessary to develop new means of prevention. In the case of the Coronaviridae this family is now recognized as including potent human pathogens causing upper and lower respiratory tract infections as well as nosocomial ones. Within the purpose of developing new antiseptics molecules, the antiseptic virucidal activity of two calix[4]arene derivatives, the tetra-para-sulfonato-calix[4]arene (C[4]S) and the 1,3-bis(bithiazolyl)-tetra-para-sulfonato-calix[4]arene (C[4]S-BTZ) were evaluated toward the human coronavirus 229E (HCoV 229E). Comparing these results with some obtained previously with chlorhexidine and hexamidine, (i) these two calixarenes did not show any cytotoxicity contrary to chlorhexidine and hexamidine, (ii) C[4]S showed as did hexamidine, a very weak activity against HCoV 229E, and (iii) the C[4]S-BTZ showed a stronger activity than chlorhexidine, i.e. 2.7 and 1.4 log10 reduction in viral titer after 5 min of contact with 10−3 mol L−1 solutions of C[4]S-BTZ and chlorhexidine, respectively. Thus, the C[4]S-BTZ appeared as a promising virucidal (antiseptic) molecule.

International audience; The bioavailability of low molecular weight heparin (LMWH) has been increased by encapsulation in nanoparticles. As a complement to these results, the cytotoxicity and apoptosis induced by LMWH nanoparticles prepared by two methods [nanoprecipitation (NP) and double emulsion (DE)] using Eudragit® RS (RS) and poly-ɛ-caprolactone (PCL) have been analysed. Particle sizes varied from 54 to 400 nm with zeta potential values between −65 and +63 mV. Our results showed that the method of nanoparticle preparation affects their properties, especially in terms of drug incorporation and cell tolerance. Cell viability ranged from 6% to 100% depending on the preparation method and physicochemical properties of the particles and the type of toxicity assay. Particle diameter and zeta potential seemed to be the most valuable cytotoxicity markers when cell viability was measured by Trypan blue exclusion and MTT respectively. Nanoparticles prepared by DE were better tolerated than those of NP. LMWH encapsulation into the cationic nanoparticles reduces remarkably their toxicity. Apoptosis evaluation showed activated caspases in exposed cells. However, no nuclear fragmentation was detected in NR8383 cells whatever the tested nanoparticles. DE nanoparticles of RS and PCL can be proposed as a good LMWH delivery system due to their low toxicity (IC50 ∼ 2.33 and 0.96 mg/mL, respectively).

Resume Trois problemes a l’heure actuelle : la multiresistance bacterienne, les infections nosocomiales (IN) et la penurie d’antibiotiques. Nous avons un besoin urgent de nouvelles molecules antibacteriennes, avec un mecanisme d’action innovant. La premiere interface bacteries/molecules, est la paroi bacterienne ; cible ideale dans la mesure ou certains elements ou motifs sont tres conserves d’un genre a un autre ou d’une espece a une autre. Mais peu nombreuses sont les techniques qui nous permettent, actuellement, d’evaluer l’impact des antibacteriens sur la structure, la composition ou les fonctions de cette paroi. Le paraguanidinoethylcalix[4]arene (ou Cx1) est un nouvel antibacterien cationique, a large spectre, non toxique, actif sur les bacteries multiresistantes (BMR), avec une cible d’action parietale potentielle, dont nous ne connaissons pas le type d’activite (bactericide ou bacteriostatique). Nous avons donc developpe, parallelement a la realisation des courbes de bactericidie, une technique de marquage des bacteries par deux fluorochromes, SYTO9® et iodure de propidium (IP), pour suivre les modifications de permeabilite membranaire, induites par le Cx1. Les resultats obtenus demontrent que, pour Escherichia coli ATCC 25922, le Cx1 possede : une activite bactericide, de type concentration-dependante ; entraine une alteration graduelle, temps et concentration dependante de la permeabilite membranaire, avec presence de formes filamenteuses. En conclusion : le double marquage SYTO9®-IP, permet une detection simple et rapide, facile a mettre en œuvre, de l’impact de nouveaux antibacteriens, sur la paroi bacterienne ; le Cx1 interagit donc bien avec la paroi bacterienne, entrainant au final une perte d’integrite membranaire.

International audience; Numerous plants are known to exhibit considerable biological activities in the fields of medicine and agriculture, yet access to their active ingredients is often complicated, cumbersome and expensive. As a consequence, many plants harbouring potential drugs or green phyto-protectants go largely unnoticed, especially in poorer countries which, at the same time, are in desperate need of antimicrobial agents. As in the case of plants such as the Jericho tomato, Solanum incanum, and the common African tree Pterocarpus erinaceus, nanosizing of original plant materials may provide an interesting alternative to extensive extraction and isolation procedures. Indeed, it is straightforward to obtain considerable amounts of such common, often weed-like plants, and to mill the dried material to more or less uniform particles of microscopic and nanoscopic size. These particles exhibit activity against Steinernema feltiae or Escherichia coli, which is comparable to the ones seen for processed extracts of the same, respective plants. As S. feltiae is used as a model nematode indicative of possible phyto-protective uses in the agricultural arena, these findings also showcase the potential of nanosizing of crude “waste” plant materials for specific practical applications, especially—but not exclusively—in developing countries lacking a more sophisticated industrial infrastructure.

Microbial cell surface properties play a central role in controlling phenomena such as bacterial adhesion and biofilm formation (on stent or on prosthesis for example). The quantification of these properties and the understanding of interactions with antibacterial compounds remain difficult, in view of the complex and dynamic nature of the cell wall constituents. Various approaches, macroscopic, microscopic or molecular, have been developped. Two of them interest us today: (i) microelectrophoresis, which permits to evaluate surface modifications by measuring eletrophoretic mobility; and (ii) atomic force microscopy (AFM), a high resolution imaging device, which allows investigations at nanometric scale. After brief presentation of principles and instrumentations, the aim of this article is to present the different applications of these techniques in Microbiology, and to discuss interest of these tools in order to investigate mechanism of action of antibacterial compounds.