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International audience; The non-mevalonate or also called MEP pathway is an essential route for the biosynthesis of isoprenoid precursors in most bacteria and in microorganisms belonging to the Apicomplexa phylum, such as the parasite responsible for malaria. The absence of this pathway in mammalians makes it an interesting target for the discovery of novel anti-infectives. As last enzyme of this pathway, IspH is an oxygen sensitive [4Fe-4S] metalloenzyme that catalyzes 2H+/2e- reductions and a water elimination by involving non-conventional bioinorganic and bioorganometallic intermediates. After a detailed description of the discovery of the [4Fe-4S] cluster of IspH, this review focuses on the IspH mechanism discussing the results that have been obtained in the last decades using an approach combining chemistry, enzymology, crystallography, spectroscopies, and docking calculations. Considering the interesting druggability of this enzyme, a section about the inhibitors of IspH discovered up to now is reported as well. The presented results constitute a useful and rational help to inaugurate the design and development of new potential chemotherapeutics against pathogenic organisms.

International audience; Persistent immune activation and dysfunction induced by infectious agents may contribute to long term comorbid conditions in individuals exposed to these pathogens. Even during successful antimicrobial treatment, increased levels of inflammation and immune cell activation and inappropriate immune cell migration and retention in tissue sites may contribute to tissue damage and end organ disease (e.g., atherosclerosis or liver or kidney damage). Understanding why some populations infected with a pathogen are able to regulate their immune responses and limit their inflammatory consequences, while other individuals may have exacerbated and persistent immune responses even during suppressive therapy, may provide insights for development of complementary immune-modulatory therapies that may reduce inflammation and morbidity and mortality in these groups. The Research Topic highlights some of these issues.Any infection induces the activation of the human immune system via various mechanisms. The problem is that although some forms of this immune activation are beneficial for the eradication of the microbial agent, others may be toxic, not only in the short term but also in the long term. It is therefore important to understand these pathogenic pathways, inasmuch as they may persist even under efficient antimicrobial therapy.

International audience; Fragment-based lead discovery has emerged over the last decades as one of the most powerful techniques for identifying starting chemical matter to target specific proteins or nucleic acids in vitro. However, the use of such low-molecular-weight fragment molecules in cell-based phenotypic assays has been historically avoided because of concerns that bioassays would be insufficiently sensitive to detect the limited potency expected for such small molecules and that the high concentrations required would likely implicate undesirable artifacts. Herein, we applied phenotype cell-based screens using a curated fragment library to identify inhibitors against a range of pathogens including Leishmania, Plasmodium falciparum, Neisseria, Mycobacterium, and flaviviruses. This proof-of-concept shows that fragment-based phenotypic lead discovery (FPLD) can serve as a promising complementary approach for tackling infectious diseases and other drug-discovery programs.

This article belongs to the Special Issue Antimicrobial Resistance, Molecular Mechanisms and Fight Strategies., Antimicrobial resistant (AMR) bacteria constitute a global health concern. Helicobacter pylori is a Gram-negative bacterium that infects about half of the human population and is a major cause of peptic ulcer disease and gastric cancer. Increasing resistance to triple and quadruple H. pylori eradication therapies poses great challenges and urges the development of novel, ideally narrow spectrum, antimicrobials targeting H. pylori. Here, we describe the antimicrobial spectrum of a family of nitrobenzoxadiazol-based antimicrobials initially discovered as inhibitors of flavodoxin: an essential H. pylori protein. Two groups of inhibitors are described. One group is formed by narrow-spectrum compounds, highly specific for H. pylori, but ineffective against enterohepatic Helicobacter species and other Gram-negative or Gram-positive bacteria. The second group includes extended-spectrum antimicrobials additionally targeting Gram-positive bacteria, the Gram-negative Campylobacter jejuni, and most Helicobacter species, but not affecting other Gram-negative pathogens. To identify the binding site of the inhibitors in the flavodoxin structure, several H. pylori-flavodoxin variants have been engineered and tested using isothermal titration calorimetry. An initial study of the inhibitors capacity to generate resistances and of their synergism with antimicrobials commonly used in H. pylori eradication therapies is described. The narrow-spectrum inhibitors, which are expected to affect the microbiota less dramatically than current antimicrobial drugs, offer an opportunity to develop new and specific H. pylori eradication combinations to deal with AMR in H. pylori. On the other hand, the extended-spectrum inhibitors constitute a new family of promising antimicrobials, with a potential use against AMR Gram-positive bacterial pathogens., We acknowledge financial support from JPIAMR (FLAV4AMR grant); INTERREG POCTEFA aCCeSS, EU (grant Infecmol); MINECO, Spain, (PID2019-107293GB-I00 grant); Gobierno de Aragón, Spain (E45_20R and LMP30_18 grants); and Maria Sklodowska-Curie grant agreement No 801586.

Objectives The occurrence and zoonotic potential of antimicrobial resistance (AMR) in pigs and broilers has been studied intensively in past decades. Here, we describe AMR levels of European pig and broiler farms and determine the potential risk factors. Methods We collected faeces from 181 pig farms and 181 broiler farms in nine European countries. Real-time quantitative PCR (qPCR) was used to quantify the relative abundance of four antimicrobial resistance genes (ARGs) [aph(3′)-III, erm(B), sul2 and tet(W)] in these faeces samples. Information on antimicrobial use (AMU) and other farm characteristics was collected through a questionnaire. A mixed model using country and farm as random effects was performed to evaluate the relationship of AMR with AMU and other farm characteristics. The correlation between individual qPCR data and previously published pooled metagenomic data was evaluated. Variance component analysis was conducted to assess the variance contribution of all factors. Results The highest abundance of ARG was for tet(W) in pig faeces and erm(B) in broiler faeces. In addition to the significant positive association between corresponding ARG and AMU levels, we also found on-farm biosecurity measures were associated with relative ARG abundance in both pigs and broilers. Between-country and between-farm variation can partially be explained by AMU. Different ARG targets may have different sample size requirements to represent the overall farm level precisely. Conclusions qPCR is an efficient tool for targeted assessment of AMR in livestock-related samples. The AMR variation between samples was mainly contributed to by between-country, between-farm and within-farm differences, and then by on-farm AMU.

International audience; The COVID-19 pandemic has the potential to affect the human microbiome in infected and uninfected individuals, having a substantial impact on human health over the long term. This pandemic intersects with a decades-long decline in microbial diversity and ancestral microbes due to hygiene, antibiotics, and urban living (the hygiene hypothesis). High-risk groups succumbing to COVID-19 include those with preexisting conditions, such as diabetes and obesity, which are also associated with microbiome abnormalities. Current pandemic control measures and practices will have broad, uneven, and potentially long-term effects for the human microbiome across the planet, given the implementation of physical separation, extensive hygiene, travel barriers, and other measures that influence overall microbial loss and inability for reinoculation. Although much remains uncertain or unknown about the virus and its consequences, implementing pandemic control practices could significantly affect the microbiome. In this Perspective, we explore many facets of COVID-19−induced societal changes and their possible effects on the microbiome, and discuss current and future challenges regarding the interplay between this pandemic and the microbiome. Recent recognition of the microbiome’s influence on human health makes it critical to consider both how the microbiome, shaped by biosocial processes, affects susceptibility to the coronavirus and, conversely, how COVID-19 disease and prevention measures may affect the microbiome. This knowledge may prove key in prevention and treatment, and long-term biological and social outcomes of this pandemic.

International audience; Cardiac toxicity can be induced by hydroxychloroquine, especially when used in combination with azithromycin. Interest in hydroxychloroquine and azithromycin as potential therapies for COVID-19 has renewed concerns about the possible cardiovascular risk these drugs present to patients with rheumatoid arthritis.

Resistance to antibiotics is a major public health issue. Urinary tract infections (UTI) represent 15% of all antibiotic prescriptions in ambulatory care. We carried out a prospective study with questionnaires including adult patients who present symptoms of UTI between June and October 2017. The main purpose was to assess whether guidelines are followed by general practionners, especially when considering postponing antibiotic therapy. 154 questionnaires were completed and results analysed. 35% of deferrable antibiotic therapies were, in fact, deferred. Fear of pyelonephritis as possible complication and patient demands were the biggest hindrance. 66% of empiric antibiotic therapies in UTI with risk of complication were suitable. Our study shows a significant difference between practices of family physicians and guidelines concerning management of UTI, mostly when antibiotic therapy could be postponed. The pertinence of such a recommendation has yet to be questioned in outpatient care.; L’antibiorésistance est un problème de santé publique majeur. Les infections urinaires (IU) représentent 15% des prescriptions antibiotiques en ville. Nous avons mené une étude prospective par questionnaires incluant les patients adultes consultant en soins primaires dans un contexte d’IU entre juin et octobre 2017. L’objectif principal était de connaître l’adéquation entre les pratiques en cabinet de médecine générale et les recommandations notamment concernant le report de l’antibiothérapie. 154 questionnaires anonymes ont été évaluables dans leur totalité. 35% des antibiothérapies décalables l’ont été. Les principaux freins déclarés étaient la peur de complication en pyélonéphrite et la pression du patient. 66% des antibiothérapies probabilistes dans les infections urinaires à risque de complication étaient conformes aux recommandations. Notre étude tend à montrer un écart significatif entre les pratiques et les recommandations dans l’antibiothérapie probabiliste des IU surtout concernant les situations où la temporisation de l’antibiothérapie est préconisée. Les résultats interrogent la pertinence de cette recommandation en médecine de ville.

Background: acute pancreatitis (AP) incidence has increased dramatically over the past years. New guidelines in 2018 were recently published in order to standardize the definition and management of AP. The aim of this study is to describe the management of children that were diagnosed with AP from the pediatric intensive care unit (PICU) in two French hospitals. Methods: this retrospective cohort study included children aged under 18 years old, who were admitted to the PICU of Robert-Debré hospital and Trousseau from 2006 to 2018 with a discharge diagnosis of AP. Data collected included management, severity and outcomes. We have also obtained data on clinical, biological and radiological presentation. Results: sixty patients were included, the median age was 8 [5-14] years and 75% had a co-morbidity mainly hematologic (26/60). Most of the AP were moderate (52%) or severe (45%). Hemodynamic failure was the main reason for PICU admission requiring a median fluid resuscitation of 56 ml/kg complemented by a median intravenous fluid therapy of 4 [2-5] ml/kg/h during the first 24 hours. Fasting has been instituted to 59 patients (98%) for a median of 4 [1-6] days, 54 patients (90%) received parenteral nutrition and 18 patients (30%) received enteral nutrition. Antibiotic therapy was given to 53 patients (88%) including 13% for curative therapy. The median length of stay in PICU was 4 [2-6] days. The mortality rate was 13%. Conclusion: this is the first French study which precisely described the management of patients with AP in PICU. It highlighted the differences with the new international guidelines. This study could improve the management of PA in PICU.; Contexte : l’incidence de la pancréatite aiguë (PA) en pédiatrie est en augmentation. De nouvelles recommandations pédiatriques ont été publiées en 2018 afin de standardiser la définition et la prise en charge des PA. L’objectif de cette étude était de décrire la prise en charge des patients hospitalisés en unité de réanimation pédiatrique (URP) pour une PA au sein de deux centres français. Méthode : cohorte rétrospective monocentrique multi-sites regroupant des patients âgés de 0 à 18 ans hospitalisés en URP à l’hôpital Robert-Debré et Trousseau entre 2006 et 2018 pour une PA. Les traitements, la sévérité, l’étiologie, les données de la présentation clinique, biologique et de l’imagerie ont été relevés ainsi que les données d’évolution. Résultats : soixante patients ont été inclus avec un âge médian de 8 [5-14] ans dont 75% présentaient une co-morbidité principalement hématologique (26/60). La majorité des PA étaient modérées (52%) ou sévères (45%). Le principal motif d’admission était la défaillance hémodynamique nécessitant un volume médian de remplissage vasculaire de 56 ml/kg complété par une hydratation médiane de 4 [2-5] ml/kg/h. La mise à jeun concernait 59 patients (98%) pour une durée médiane de 4 [1-6] jours, une nutrition entérale a été administrée à 18 patients (30%) et une nutrition parentérale à 54 patients (90%). Une antibiothérapie a été administrée à 53 patients (88%) dont 8 (13%) à visée curative. Le délai médian d’hospitalisation en URP était de 4 [2-6] jours avec une mortalité à la sortie de 13%. Conclusion : cette première étude française sur les PA en URP permet d’analyser nos pratiques et de les comparer aux récentes recommandations internationales.

Antimicrobial resistance continues to rise in the world. They are more and more complex and unpredictable, increase the risk of therapeutic mismatch and the mortality of patients. In this context, the culture agar Mueller Hinton Rapid (MHR, i2a) provides a quick antibiotic susceptibility results from blood culture or urinalysis in 6 to 8 hours in order to optimize the antibiotic therapy. The object of this study was to evaluate their impact on the early antibiotic therapy adaptation for patients treated for bloodstream infection or urinary tract infections. A prospective study has been realized. The antibiotic susceptibility tests from urinary samples and positive blood cultures with Enterobacteriaceae and S. aureus have been seed in MHR agar. The antibiotic susceptibility results were transmitted to the antimicrobial stewardship team. The antibiotic susceptibility results and the antibiotic therapy adaptation's delay were collected and retrospectively compared. For bloodstream infections, 163 patients were included and compared with 167 patients. The average therapy adjustment time was 7h (+/-2h30) versus 18h (+/-3h40) (p

Objectives Pressure ulcers are frequently observed in spinal cord injury (SCI) patients. They can be life-threatening and are a major medico-economic burden. Despite their frequency, their pathophysiology and optimal management are still poorly understood. Most available data comes from non-comparative studies, especially in terms of antimicrobial use. Methods We performed a critical review of the literature and opinions of infectious disease specialists based in a French expert center for this disease. We mainly focused on antimicrobial treatments prescribed in this situation. Results These infections are usually clinically diagnosed. Microbiological samples are not the gold standard for this assessment. Furthermore, reliable microbiological identification is a major challenge but should help select antimicrobial treatment. Imaging technique could be helpful but cannot replace the physical examination. The choice of antimicrobials must consider the potential ecological collateral damages in this vulnerable population. Antimicrobial therapy should be as short as possible, adapted to the microbiological identification, and must have suitable bioavailability. Conclusion Management of infected pressure ulcers is a major concern in disabled patients already highly exposed to antimicrobial treatment and multidrug-resistant organisms colonization. Extensive data is required.

International audience; Due to the continuing global concerns involving antibiotic resistance, there is a need for scientific forums to assess advancements in the development of antimicrobials and their alternatives that might reduce development and spread of antibiotic resistance among bacterial pathogens. The objectives of the 2nd International Symposium on Alternatives to Antibiotics were to highlight promising research results and novel technologies that can provide alternatives to antibiotics for use in animal health and production, assess challenges associated with their authorization and commercialization for use, and provide actionable strategies to support their development. The session on microbial-derived products was directed at presenting novel technologies that included exploiting CRISPR-Cas nucleases to produce sequence-specific antimicrobials, probiotics development via fecal microbiome transplants among monogastric production animals such as chickens and mining microbial sources such as bacteria or yeast to identify new antimicrobial compounds. Other research has included continuing development of antimicrobial peptides such as newly discovered bacteriocins as alternatives to antibiotics, use of bacteriophages accompanied by development of unique lytic proteins with specific cell-wall binding domains and novel approaches such as microbial-ecology guided discovery of anti-biofilm compounds discovered in marine environments. The symposium was held at the Headquarters of the World Organisation for Animal Health (OIE) in Paris, France during 12–15 December 2016.

International audience; Although CRISPR-Cas systems naturally evolved to provide adaptive immunity in bacteria and archaea, Cas nucleases can be co-opted to target chromosomal sequences rather than invasive genetic elements. Although genome editing is the primary outcome of self-targeting using CRISPR-based technologies in eukaryotes, self-targeting by CRISPR is typically lethal in bacteria. Here, we discuss how DNA damage introduced by Cas nucleases in bacteria can efficiently and specifically lead to plasmid curing or drive cell death. Specifically, we discuss how various CRISPR-Cas systems can be engineered and delivered using phages or phagemids as vectors. These principles establish CRISPR-Cas systems as potent and programmable antimicrobials, and open new avenues for the development of CRISPR-based tools for selective removal of bacterial pathogens and precise microbiome composition alteration.

Introduction The etiological diagnosis of infectious encephalitis is often not established 48 hours after onset. We aimed to review existing literature data before providing management guidelines. Method We performed a literature search on PubMed using filters such as “since 01/01/2000”, “human”, “adults”, “English or French”, and “clinical trial/review/guidelines”. We also used the Mesh search terms “encephalitis/therapy” and “encephalitis/diagnosis”. Results With Mesh search terms “encephalitis/therapy” and “encephalitis/diagnosis”, we retrieved 223 and 258 articles, respectively. With search terms “encephalitis and corticosteroid”, we identified 38 articles, and with “encephalitis and doxycycline” without the above-mentioned filters we identified 85 articles. A total of 210 articles were included in the analysis. Discussion Etiological investigations must focus on recent travels, animal exposures, age, immunodeficiency, neurological damage characteristics, and potential extra-neurological signs. The interest of a diagnosis of encephalitis for which there is no specific treatment is also to discontinue any empirical treatments initially prescribed. Physicians must consider and search for autoimmune encephalitis.

Referred to by :Recommandations de prise en charge des encéphalites infectieuses de l’adulte – reprise de la version françaisePratique Neurologique - FMC, Volume 9, Issue 3, September 2018, Pages 195-203; International audience; Recommendations/Recommandations

Background Artemisinin-resistant Plasmodium falciparum malaria parasites are now present across much of mainland Southeast Asia, where ongoing surveys are measuring and mapping their spatial distribution. These efforts require substantial resources. Here we propose a generic ‘smart surveillance’ methodology to identify optimal candidate sites for future sampling and thus map the distribution of artemisinin resistance most efficiently. Methods The approach uses the ‘uncertainty’ map generated iteratively by a geostatistical model to determine optimal locations for subsequent sampling. Results The methodology is illustrated using recent data on the prevalence of the K13-propeller polymorphism (a genetic marker of artemisinin resistance) in the Greater Mekong Subregion. Conclusion This methodology, which has broader application to geostatistical mapping in general, could improve the quality and efficiency of drug resistance mapping and thereby guide practical operations to eliminate malaria in affected areas. Electronic supplementary material The online version of this article (doi:10.1186/s12942-016-0064-6) contains supplementary material, which is available to authorized users.

Objectives The present study was carried out to determine the antidiarrheal effects of myrtle (Myrtus communis L.) berries seeds aqueous extract (MBSAE) from Tunisia as well as the involvement of its antimicrobial and antioxidant properties in such protection. Methods Adult male wistar rats were used and divided into six groups of ten each: control, Castor oil, Castor oil + Loperamide and Castor oil + various doses of MBSAE. Animals were per orally (p.o.) pre-treated with MBSAE for one hour and intoxicated by castor oil acute oral administration. Key findings Our results demonstrated that the MBSAE is rich in total and condensed tannins and exhibited a broad spectrum of antibacterial activity. In vivo, we found that MBSAE administration induced a significant dose-dependent protection against diarrhoea and intestinal fluid accumulation. Castor oil-induced intestinal hypersecretion was accompanied by an oxidative stress status in the intestine. More importantly, we showed that acute diarrhoea was accompanied by an increase in intestinal mucosa hydrogen peroxide (H2O2), calcium and free iron levels while MBSAE pre-treatment reversed all castor oil-induced intracellular mediators disturbances. Conclusions We suggest that MBSAE had a potent protective effects against castor oil-induced acute diarrhoea due in part to its antioxidant and antimicrobial properties.

International audience; A putative genome duplication event within the Silurana lineage has given rise to the tetraploid frog S. paratropicalis and a second polyploidization within the Xenopus lineage has produced the octoploid frog X. andrei. Peptidomic analysis of norepinephrine-stimulated skin secretions of S. paratropicalis and X. andrei led to identification of multiple peptides with growth-inhibitory activity against Escherichia coli and Staphylococcus aureus. Structural characterization demonstrated that the S. paratropicalis components comprised three peptides belonging to the caerulein-precursor fragment family (CPF-SP1, -SP2 and -SP3), two peptides from the xenopsin-precursor fragment family (XPF-SP1 and -SP2), and one peptide orthologous to peptide glycine-leucine-amide (PGLa-SP1). The CPF peptides showed potent, broad-spectrum antimicrobial activity. The X. andrei components comprised two peptides from the magainin family, (magainin-AN1 and -AN2), two from the XPF family (XPF-AN1 and -AN2), two from the PGLa family(PGLa-AN1 and -AN2), and one caerulein-precursor fragment (CPF-AN1).The primary structures of these peptides indicate a close phylogenetic relationship between X. andrei and the octoploid frog X. amieti. Under the same experimental conditions, seven orthologous antimicrobial peptides were previously isolated from the diploid frog S. tropicalis, nine from the tetraploid frog X. borealis, and five from the tetraploid frog X. clivii. The data indicate, therefore, that nonfunctionalization (gene deletion) has been the most common fate of duplicated antimicrobial peptide genes following polyploidization events in the Silurana and Xenopus lineages.

International audience; Five peptides with antimicrobial activity were isolated from norepinephrine-stimulated skin secretions of the tetraploid frog Xenopus clivii Peracca, 1898 (Pipidae). Characterization of the peptides demonstrated that they are structurally similar to magainins (2 peptides), caerulein-precursor fragments, CPF (2 peptides), and xenopsin-precursor fragments, XPF (1 peptide) that have been previously isolated from other species of the genus Xenopus. The magainins and the XPF peptide were active only against the Gram-negative microorganism Escherichia coli whereas the CPF peptides were also active against the Gram-positive Staphylococcus aureus. The most abundant antimicrobial peptide in the secretions, CPF-C1 (GFGSLLGKALRLG ANVL.NH(2)) inhibited the growth of the Gram-negative bacteria Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa (MIC≤25μM) suggesting potential for development into an anti-infective agent for use against these emerging antibiotic-resistant pathogens.

International audience; Populations of the Chiricahua leopard frog Lithobates chiricahuensis (Ranidae) occupying regions in southern Arizona (southern range) are morphologically distinct from those from the Mogollon Rim of central Arizona (northern range) and a comparison of DNA sequences of mitochondrial genes has suggested that they may represent separate species. Peptidomic analysis of norepinephrine-stimulated skin secretions has led to the identification of six peptides with antimicrobial activity in samples from specimens from both groups. The primary structure of the peptides (esculentin-2 CHa, ranatuerin-2 CHa, -CHb, and -CHc, and brevinin-1 CHa and -CHb) isolated from both southern and northern range frogs are identical consistent with the proposal that the two populations are conspecific. However, palustrin-2CHa and the atypical brevinin-1 CHc (FFPTIAG*****LTKLFCA ITKKC), containing a five amino acid residue deletion, were identified only in secretions from southern range specimens. Consequently, there is some support for the proposal that the two populations are closely related but separate species but this support is relatively weak. Esculentin-2 CHa (GFSSIFRGVAKFASKGLG KDLAKLGVDLVACKISKQC) displayed the highest antimicrobial potency (MIC ≤ 10μM) against a variety of microorganisms and was only moderately hemolytic (LC(50) = 150 μM). Cladistic analysis based upon the primary structures of brevinin-1 peptides indicates a close phylogenetic relationship between L. chiricahuensis, L. onca, and L. yavapaiensis.

Background: In developing countries, knowledge of antimicrobial resistance patterns is essential to define empirical therapy. Methodology: All the surgery and intensive care wards of two hospitals in Antananarivo were included to study the antimicrobial susceptibility of the pathogenic bacteria causing nosocomial infections. A repeated cross-sectional survey was conducted between September 2006 and March 2008, one day per week. Isolates were identified using classical methods, and resistance to antibiotics was assessed according to the recommendations of the Antibiogram Committee of the French Microbiology Society. Results: Clinical specimens from 706 from 651 patients were collected. Of the 533 bacterial pathogens, 46.7% were Enterobacteriaceae , 19.3% were Staphylococcus aureus , and 19.1% were pathogens from the hospital environment ( Pseudomonas aeruginosa and Acinetobacter baumannii ).Frequencies of resistance were high, particularly in Enterobacteriaceae ; however, the rate of Staphylococcus aureus isolates resistant to oxacillin (13.6 %) was moderate and all these isolates were susceptible to glycopeptids. The percentages of isolates susceptible to ceftazidim were 81.8% for E. coli , 60.9% for Klebsiella , and 52.5% for Enterobacter spp. Resistance to third-generation cephalosporins was due to extended spectrum betalactamases (ESBL). Multivariate analysis showed that diabetes (adjusted OR: 3.9) and use of an invasive procedures (adjusted OR: 3.5) were independent risk factors for resistance to third-generation cephalosporins. Conclusion: A nationwide surveillance programme is needed to monitor the microbial trends and antimicrobial resistance in Madagascar.

International audience; Methanolic extracts prepared from the leaves, twigs and the roots of Vismia laurentii De Wild as well as nine compounds isolated from these crude extracts, were tested for their antimicrobial activity against Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and two Candida species using disc diffusion and well micro-dilution methods. The disc diffusion assay indicated that the crude extract was active against all the pathogens tested, whereas isolated compounds showed selective activities. The degree of sensitivity of the test organisms to purified compounds varied from 25 to 90%. Fridelin (8) was found to be the most active compound, while Bivismiaquinone (3) was the least active. The lowest minimum inhibition concentration (MIC) values as obtained by the micro-dilution assays were 19.53 and 1.22 microg/ml for the crude extracts and purified compounds, respectively. The lowest value for the purified compounds (1.22 microg/ml) was obtained with O(1)-demethyl-3',4'-deoxypsorospermin-3',4'-diol (6) on Candida gabrata and Bacillus subtilis; 1,8-dihydroxy-6-methoxy-3-methylanthraquinone (5) on Bacillus subtilis and 6-deoxyisojacareubin (7) on Bacillus stearothermophilus. These results provide promising baseline information for the potential use of these crude extracts as well as some of the isolated compounds in the treatment of bacterial and fungal infections.

International audience; Enrofloxacin and marbofloxacin are two veterinary fluoroquinolones used to treat severe bacterial infections in horses. A repeated measures study has been designed to compare their pharmacokinetic parameters, to investigate their bioavailability and to estimate their absorbed fraction and first-pass effect by using plasma, urinary and metabolite data collected from five healthy mares. Clearance and V(d(ss)) were greater for enrofloxacin (mean +/- SD = 6.34 +/- 1.5 mL/min/kg and 2.32 +/- 0.32 L/kg, respectively) than for marbofloxacin (4.62 +/- 0.67 mL/min/kg and 1.6 +/- 0.25 L/kg, respectively). Variance of the AUC(0-inf) of marbofloxacin was lower than that for enrofloxacin, with, respectively, a CV = 15% and 26% intravenously and a CV = 31% and 55% after oral administration. Mean oral bioavailability was not significantly different between marbofloxacin (59%) and enrofloxacin (55%). The mean percentage of the dose eliminated unchanged in urine was significantly higher for marbofloxacin (39.7%) than that for enrofloxacin (3.4%). Absorbed fraction and first-pass effect were only determinable for enrofloxacin, whereas the percentage of the dose absorbed in the portal circulation was estimated to be 78% and the fraction not extracted during the first pass through the liver was 65%. Consequently, the moderate observed bioavailability of enrofloxacin appears to be mainly caused by hepatic first-pass effect.

International audience; Methicillin-resistant Staphylococcus aureus (MRSA) is the most frequent cause of hospital-acquired infection, which manifests as surgical site infections, bacteremia, and sepsis. Due to drug-resistance, prophylaxis of MRSA infection with antibiotics frequently fails or incites nosocomial diseases such as Clostridium difficile infection. Sortase A is a transpeptidase that anchors surface proteins in the envelope of S. aureus, and sortase mutants are unable to cause bacteremia or sepsis in mice. Here we used virtual screening and optimization of inhibitor structure to identify 3-(4-pyridinyl)-6-(2-sodiumsulfonatephenyl)[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole and related compounds, which block sortase activity in vitro and in vivo. Sortase inhibitors do not affect in vitro staphylococcal growth yet protect mice against lethal S. aureus bacteremia. Thus, sortase inhibitors may be useful as antiinfective therapy to prevent hospital-acquired S. aureus infection in high-risk patients without the side effects of antibiotics.

International audience; The primary structures of host-defense peptides have proved useful in elucidating the evolution history of frogs. Peptidomic analysis was used to compare the diversity of host-defense peptides in norepinephrine-stimulated skin secretions from the octoploid frogs, Xenopus vestitus (Kivu clawed frog) and Xenopus wittei (De Witte's clawed frog) in the family Pipidae. Structural characterization demonstrated that the X. vestitus peptides belong to the magainin (3 peptides), peptide glycine-leucine-amide (PGLa; 4 peptides), xenopsin-precursor fragment (XPF; 1 peptide), and caerulein-precursor fragment (CPF; 5 peptides) families. The X. wittei peptides comprise magainin (4 peptides), PGLa (1 peptide), XPF (2 peptides), and CPF (7 peptides). In addition, secretions from both species contain caerulein, identical to the peptide from Xenopus laevis, but X. wittei secretions contains the novel peptide [R4K]xenopsin. The variability in the numbers of paralogs in each peptide family indicates a selective silencing of the host-defense peptide genes following the polyploidization events. The primary structures of the peptides provide insight into phylogenetic relationships among the octoploid Xenopus frogs. The data support a sister-group relationship between X. vestitus and Xenopus lenduensis, suggestive of bifurcating speciation after allopolyploidization, whereas X. wittei is more closely related to the Xenopus amieti-Xenopus andrei group suggesting a common tetraploid ancestor. Consistent with previous data, the CPF peptides showed the highest growth inhibitory activity against bacteria with CPF-W6 (GIGSLLAKAAKLAAGLV.NH2) combining high antimicrobial potency against Staphylococcus aureus (MIC=4 μM) with relatively low hemolytic activity (LC50=190 μM).

Stable resistance to metronidazole in a nontoxigenic Clostridium difficile strain was investigated at both the genomic and proteomic levels. Alterations in the metabolic pathway involving the pyruvate-ferredoxin oxidoreductase were found, suggesting that reduction of metronidazole, required for its activity, may be less efficient in this strain. Proteomic studies also showed a cellular response to oxidative stress.

International audience; Corticosteroids have been shown to reduce short-term mortality during septic shock and therefore recommended in the most severe patients as adjuvant therapy. Until recently, recombinant human activated protein C (APC) was also considered in the management of more severe cases. As myocardial depression has long been recognized as a manifestation of organ dysfunction during septic shock, we examined whether corticosteroids (dexamethasone, 150 µg/kg per hour) and/or APC (33 µg/kg per hour) treatments improve sepsis-induced cardiac dysfunction during cecal ligature and puncture-induced septic shock in Wistar rats. All rats received intravenous saline resuscitation (10 mL/kg per hour) and antibiotics. Eighteen hours after surgery, anesthesia was performed (isoflurane), and myocardial function was assessed using a conductance catheter introduced into the left ventricle. Rats were then killed; blood and heart were harvested for biological analysis, including radical oxygen species determination. Cecal ligature and puncture induced hypotension, depression of myocardial systolic performance (demonstrated by significant decreases in dP/dtmax [first derivative of maximal developed pressure during isovolumetric contraction], end-systolic pressure-volume relationship, and preload recruitable stroke work) and alteration of diastolic function (dP/dtmin [first derivative of minimal developed pressure during isovolumetric relaxation]), whereas dexamethasone, APC, and their combination thereof allowed correction of hemodynamic disorders and improved myocardial mechanical efficiency. Cecal ligature and puncture was associated with higher levels of nitric oxide and superoxide anion (O2) in heart (electron paramagnetic resonance studies) and consequently peroxynitrite. Dexamethasone and APC also improved cardiac dysfunction by downregulating the inducible nitric oxide synthase pathway and reducing myocardial oxidative stress.

Lactoferrin is an iron-binding glycoprotein found in exocrine secretions of mammals and released from neutrophilic granules during inflammation. This review describes the biological roles of lactoferrin in host defence. Secreted lactoferrin exerts antimicrobial action either by chelation of iron or by destabilization of bacterial membranes. Furthermore, lactoferrin modulates the inflammatory process, mainly by preventing the release of cytokines from monocytes and by regulating the proliferation and differentiation of immune cells. Some of these activities are related to the ability of lactoferrin to bind lipopolysaccharides (LPS) with high affinity. Indeed, recentin vitrostudies indicate that lactoferrin is able to compete with the LPS-binding protein for LPS binding and therefore to prevent the transfer of LPS to CD14 present at the surface of monocytes. Moreover, the prophylactic properties of lactoferrin against septicemiain vivohave been demonstrated. Taken as a whole, these observations strongly suggest that lactoferrin is one of the key molecules which modulate the inflammatory response.

The Sinorhizobium meliloti BacA ABC transporter protein plays an important role in its nodulating symbiosis with the legume alfalfa ( Medicago sativa ). The Mycobacterium tuberculosis BacA homolog was found to be important for the maintenance of chronic murine infections, yet its in vivo function is unknown. In the legume plant as well as in the mammalian host, bacteria encounter host antimicrobial peptides (AMPs). We found that the M. tuberculosis BacA protein was able to partially complement the symbiotic defect of an S. meliloti BacA-deficient mutant on alfalfa plants and to protect this mutant in vitro from the antimicrobial activity of a synthetic legume peptide, NCR247, and a recombinant human β-defensin 2 (HBD2). This finding was also confirmed using an M. tuberculosis insertion mutant. Furthermore, M. tuberculosis BacA-mediated protection of the legume symbiont S. meliloti against legume defensins as well as HBD2 is dependent on its attached ATPase domain. In addition, we show that M. tuberculosis BacA mediates peptide uptake of the truncated bovine AMP, Bac7 1-16 . This process required a functional ATPase domain. We therefore suggest that M. tuberculosis BacA is important for the transport of peptides across the cytoplasmic membrane and is part of a complete ABC transporter. Hence, BacA-mediated protection against host AMPs might be important for the maintenance of latent infections.

International audience; Norepinephrine-stimulated skin secretions of the Tyrrhenian painted frog Discoglossus sardus Tschudi, 1837 (Alytidae) did not contain any peptide with antimicrobial or hemolytic activity. However, peptidomic analysis of the secretions revealed the presence of an abundant peptide with structural similarity to frenatin 2, previously isolated from the Australian frog Litoria infrafrenata (Hylidae). The primary structure of the peptide, termed frenatin 2D, was established as DLLGTLGNLPLPFI.NH2 by automated Edman degradation and mass spectrometry with electron-transfer dissociation (ETD)-based fragmentation and confirmed by chemical synthesis. The structure of a second frenatin 2-related peptide, termed frenatin 2.1D, that was present in much lower abundance was established as GTLGNLPAPFPG. Frenatin 2D (20 μg/ml) significantly stimulated production of the proinflammatory cytokines TNF-α (P

International audience; Antimicrobial peptides (AMPs) are found in various classes of organisms as part of the innate immune system. Despite high sequence variability, they share common features such as net positive charge and an amphipathic fold when interacting with biologic membranes. Esculentin-1b is a 46-mer frog-skin peptide, which shows an outstanding antimicrobial activity. Experimental studies revealed that the N-terminal fragment encompassing the first 18 residues, Esc(1-18), is responsible for the antimicrobial activity of the whole peptide, with a negligible toxicity toward eukaryotic cells, thus representing an excellent candidate for future pharmaceutical applications. Similarly to most of the known AMPs, Esc(1-18) is expected to act by destroying/permeating the bacterial plasma-membrane but, to date, its 3D structure and the detailed mode of action remains unexplored. Before an in-depth investigation on peptide/membranes interactions could be undertaken, it is necessary to characterize peptide's folding propensity in solution, to understand what is intrinsically due to the peptide sequence, and what is actually driven by the membrane interaction. Circular dichroism and nuclear magnetic resonance spectroscopy were used to determine the structure adopted by the peptide, moving from water to increasing amounts of trifluoroethanol. The results showed that Esc(1-18) has a clear tendency to fold in a helical conformation as hydrophobicity of the environment increases, revealing an intriguing amphipathic structure. The helical folding is adopted only by the N-terminal portion of the peptide, while the rest is unstructured. The presence of a hydrophobic cluster of residues in the C-terminal portion suggests its possible membrane-anchoring role.

International audience; Skin secretions of frogs from the subfamily Xenopodinae (Xenopus+Silurana) within the family Pipidae are a rich source of antimicrobial peptides with therapeutic potential but species from the sister taxon Hymenochirus in the subfamily Pipinae (Hymenochirus+Pseudhymenochirus+Pipa) have not been investigated. Peptidomic analysis of norepinephrine-stimulated skin secretions from two distinct populations of the Congo dwarf clawed frog Hymenochirus boettgeri (Tornier, 1896) has led to identification of five structurally related peptides with broad-spectrum antimicrobial activity. Hymenochirin-1B (IKLSPETKDNLKKVLKGAIKGAIAVAKMV.NH(2)) is C-terminally α-amidated whereas hymenochirins-2B-5B have the general structure XKIPX(2)VKDTLKKVAKGX(2)SX(2)AGAX(3).COOH. Hymenochirin-3B (IKIPAVVKDTLKKVAKGVLSAVAGALTQ) was the most abundant peptide in the secretions. The hymenochirins show very low structural similarity with the antimicrobial peptides isolated from skin secretions of Silurana tropicalis and Xenopus laevis consistent with the proposed ancient divergence of the Pipinae and Xenopodinae. Synthetic replicates of hymenochirin-1B-4B inhibit the growth of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus (MIC in the range 10-40 μM) and Candida albicans (MIC=80 μM). The peptides display relatively weak hemolytic activity against human erythrocytes (LC(50) in the range 160 to >300 μM).

International audience; BACKGROUND: Fluoroquinolones are frequently prescribed for non complicated urinary tract infection treatments and have a negative ecological impact. We aimed to substitute them by antibiotics with narrower activity spectrum in order to preserve fluoroquinolone activity in complicated hospital infections. OBJECTIVE: To assess the impact of a multi-modal approach that combines the dispatching of antibiotic prescription guidelines and voluntary attendance at educational sessions on general practitioners' (GP) antibiotic prescription habits. SETTING: This study was led in Franche-Comté, a French eastern region, where GPs were given a guideline recommending a restricted use of fluoroquinolones for urinary tract infections. METHOD: Segmented regression analysis of interrupted time series was used to assess changes in antibiotic prescription. MAIN OUTCOME MEASURE: The antibiotic prescription data of nitrofurantoin, fosfomycin-trometamol and fluoroquinolones for women aged 15-65 years were obtained from the regional agency of health insurance. RESULTS: Twenty months after intervention, the number of nitrofurantoin and fosfomycintrometamol prescriptions increased by 36.8% (95% CI: 30.6-42.2) and 28.5% (95% CI: 22.9-35.4), respectively, while that of norfloxacin decreased by 9.1% (95% CI: -15.3 to -3.5). CONCLUSION: This study suggests that the dispatch of the guideline on urinary tract infection had a moderate impact on antibiotic prescriptions.

International audience; RATIONALE: Measuring the attributable mortality of ventilator-associated pneumonia (VAP) is challenging and prone to different forms of bias. Studies addressing this issue have produced variable and controversial results. OBJECTIVES: We estimate the attributable mortality of VAP in a large multicenter cohort using statistical methods from the field of causal inference. METHODS: Patients (n = 4,479) from the longitudinal prospective (1997-2008) French multicenter Outcomerea database were included if they stayed in the intensive care unit (ICU) for at least 2 days and received mechanical ventilation (MV) within 48 hours after ICU admission. A competing risk survival analysis, treating ICU discharge as a competing risk for ICU mortality, was conducted using a marginal structural modeling approach to adjust for time-varying confounding by disease severity. MEASUREMENTS AND MAIN RESULTS: Six hundred eighty-five (15.3%) patients acquired at least one episode of VAP. We estimated that 4.4% (95% confidence interval, 1.6-7.0%) of the deaths in the ICU on Day 30 and 5.9% (95% confidence interval, 2.5-9.1%) on Day 60 are attributable to VAP. With an observed ICU mortality of 23.3% on Day 30 and 25.6% on Day 60, this corresponds to an ICU mortality attributable to VAP of about 1% on Day 30 and 1.5% on Day 60. CONCLUSIONS: Our study on the attributable mortality of VAP is the first that simultaneously accounts for the time of acquiring VAP, informative loss to follow-up after ICU discharge, and the existence of complex feedback relations between VAP and the evolution of disease severity. In contrast to the majority of previous reports, we detected a relatively limited attributable ICU mortality of VAP.

Background: Antibiotics have been shown to improve hidradenitis suppurativa (HS) patients but complete remission is rare using these treatments. Objective: To assess the efficacy and safety of a combination of oral rifampin, moxifloxacin and metronidazole in long-lasting refractory HS. Methods: We retrospectively studied 28 consecutive HS patients including 6, 10 and 12 Hurley stage 1, 2 and 3 patients, respectively. Complete remission, defined as a clearance of all inflammatory lesions including hypertrophic scars, was the main outcome criterion of the study. Results: Complete remission was obtained in 16 patients, including 6/6, 8/10 and 2/12 patients with Hurley stage 1, 2 and 3, respectively (p = 0.0004). The median duration of treatment to obtain complete remission was 2.4 (range 0.9–6.5) and 3.8 months (range 1.6–7.4) in stage 1 and 2 patients, respectively, and 6.2 and 12 months in the 2 stage 3 patients. Main adverse events of the treatments were gastrointestinal disorders (64% of patients) and vaginal candidiasis (35% of females). Reversible tendinopathy and hepatitis occurred in 4 and 1 patient, respectively. Conclusions: Complete remission of refractory HS can be obtained using broad-spectrum antibiotics and Hurley staging is a prognostic factor of response to the treatment.

Item does not contain fulltext To gain an in-depth grasp of infectious processes one has to know the specific interactions between the virulence factors of the pathogen and the host defense mechanisms. A thorough understanding is crucial for identifying potential new drug targets and designing drugs against which the pathogens might not develop resistance easily. Model organisms are a useful tool for this endeavor, thanks to the power of their genetics. Drosophila melanogaster is widely used to study host-pathogen interactions. Its basal immune response is well understood and is briefly reviewed here. Considerations relevant to choosing an adequate infection model are discussed. This review then focuses mainly on infections with two categories of pathogens, the well-studied Gram-negative bacterium Pseudomonas aeruginosa and infections by fungi of medical interest. These examples provide an overview over the current knowledge on Drosophila-pathogen interactions and illustrate the approaches that can be used to study those interactions. We also discuss the usefulness and limits of Drosophila infection models for studying specific host-pathogen interactions and high-throughput drug screening. 01 juni 2011

International audience; Nine peptides with differential growth inhibitory activity against Escherichia coli and Staphylococcus aureus were isolated from norepinephrine-stimulated skin secretions of the tetraploid frog Xenopus borealis Parker, 1936 (Pipidae). Structural characterization of the peptides demonstrated that they were orthologous to magainin-2 (1 peptide), peptide glycine-leucine-amide, PGLa (2 peptides), caerulein-precursor fragments, CPF (4 peptides), and xenopsin-precursor fragments, XPF (2 peptides), previously isolated from Xenopus laevis and X. amieti. In addition, a second magainin-related peptide (G**KFLHSAGKFGKAFLGEVMIG) containing a two amino acid residue deletion compared with magainin-2 was identified that had only weak antimicrobial activity. The peptide with the greatest potential for development into a therapeutically valuable anti-infective agent was CPF-B1 (GLGSLLGKAFKIGLKTVGKMMGGAPREQ) with MIC=5 microM against E. coli, MIC=5 microM against S. aureus, and MIC=25 microM against Candida albicans, and low hemolytic activity against human erythrocytes (LC(50)>200 microM). This peptide was also the most abundant antimicrobial peptide in the skin secretions. CPF-B1 was active against clinical isolates of the nosocomial pathogens, methicillin-resistant S. aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDRAB) with MIC values in the range 4-8 microM.

International audience; Recent reports on the decline of the efficacy of artemisinin-based combination therapies (ACTs) indicate a serious threat to malaria control. The endoplasmic/sarcoplasmic reticulum Ca(2+)-ATPase ortholog of Plasmodium falciparum (PfSERCA) has been suggested to be the target of artemisinin and its derivatives. It is assumed that continuous artemisinin pressure will affect polymorphism of the PfSERCA gene (serca) if the protein is the target. Here, we investigated the polymorphism of serca in parasite populations unexposed to ACTs to obtain baseline information for the study of potential artemisinin-driven selection of resistant parasites. Analysis of 656 full-length sequences from 13 parasite populations in Africa, Asia, Oceania, and South America revealed 64 single nucleotide polymorphisms (SNPs), of which 43 were newly identified and 38 resulted in amino acid substitutions. No isolates showed L263E and S769N substitutions, which were reportedly associated with artemisinin resistance. Among the four continents, the number of SNPs was highest in Africa. In Africa, Asia, and Oceania, common SNPs, or those with a minor allele frequency of ≥0.05, were less prevalent, with most SNPs noted to be continent specific, whereas in South America, common SNPs were highly prevalent and often shared with those in Africa. Of 50 amino acid haplotypes observed, only one haplotype (3D7 sequence) was seen in all four continents (64%). Forty-eight haplotypes had frequencies of less than 5%, and 40 haplotypes were continent specific. The geographical difference in the diversity and distribution of serca SNPs and haplotypes lays the groundwork for assessing whether some artemisinin resistance-associated mutations and haplotypes are selected by ACTs.

The Volcano clawed frog Xenopus amieti Kobel, du Pasquier, Fischberg, and Gloor, 1980, with a chromosome number of 2 n = 72, is believed to have undergone two rounds of genome duplication since evolving from a diploid ancestor. Nine peptides with differential antimicrobial activity against Escherichia coli and Staphylococcus aureus were isolated from norepinephrine-stimulated skin secretions of X. amieti that showed structural similarity to peptides previously isolated from the tetraploid frog X . laevis (2 n = 36) and the diploid frog Silurana (formerly Xenopus ) tropicalis (2 n = 20). Two peptides (magainin-AM1 and -AM2) are othologous to the magainins, two peptides (PGLa-AM1 and -AM2) orthologous to peptide glycine–leucine-amide, four peptides (CPF-AM1, -AM2, -AM3, -AM4) orthologous to caerulein-precursor fragments, and one peptide (XPF-AM1) structurally similar to xenopsin-precursor fragments were characterized. CFP-AM1 (GLGSVLGKALKIGANLL.NH 2 ) was the most potent peptide present in the secretions and magainin-AM2 (GVSKILHSAGKFGKAFLGEIMKS) was the most abundant. The data indicate that nonfunctionalization has been the most common fate of duplicated antimicrobial peptide genes following the polyploidization events in the X. amieti lineage. However, the very low antimicrobial activity of the magainin-AM1 and PGLa-AM2 paralogs suggests the possibility that certain peptides may have evolved toward a new, as yet undetermined, function (neofunctionalization).

Morphological evidence and data from comparisons of nucleotide sequences of mitochondrial genes demonstrate considerable intraspecies variation among populations of the Japanese brown frog Rana tagoi Okada 1928 (Tago's brown frog). Five peptides with antimicrobial activity were isolated from an extract of the skins of specimens of Rana tagoi okiensis collected on the Oki Islands, Japan. Determination of their primary structures demonstrated that two peptides belong to the ranatuerin-2 family, two peptides to the temporin family, and one peptide to the brevinin-1 family. Ranatuerin-2 peptides were not previously identified in the skin of specimens of R. t. tagoi collected in Chiba Prefecture, Japan and the structures of the temporin peptides from R. t. okiensis (temporin-TOa: FLPILGKLLSGFL.NH 2 and temporin-TOb: FLPILGKLLSGLL.NH 2 ) are different from temporin-TGa (FLPILGKLLSGIL.NH 2 ) isolated from R. t. tagoi. Similarly, the acyclic C-terminally α-amidated brevinin-1 peptide from R. t. okiensis (Brevinin-1TOa, GIGSILGVIAKGLPTLISWIKNR.NH 2 ) shows three amino acid substitutions (Gly 1 → Ala, Val 8 → Ala, Ile 9 → Leu) compared to the ortholog from R. t. tagoi . In addition, bradykinin, identical to the mammalian peptide, is present in high concentration in the skin of R. t. okiensis but not R. t. tagoi . The data provide evidence to support the proposal that R. t. tagoi and R. t. okiensis should be regarded as separate species ( R. tagoi and R. okiensis ) rather than conspecific subspecies.

International audience; 2-D and 3-D NMR techniques were used to investigate the conformations in solution of several peptides and proteins for which crystalline structures are not available yet. Insect defensin A is a small (40 aa) antibiotic protein exhibiting a characteristic 'loop-helix-beta-sheet' structure. A striking analogy was found with charybdotoxin, a scorpion toxin in which a CSH (cysteine stabilized alpha-helix) motif is also present. Wheat phospholipid transfer protein (PLTP) (90 aa) has a 3-D structure resulting from the packing of four helices and of a C-terminal less well-defined fragment. Preliminary results show that PLTP forms a complex with lyso-PC and that such an interaction results in a conformational change affecting principally the C-terminal half of the protein. A last example is given with surfactin, a lipopeptide biosurfactant from bacterial origin. Its protonated form shows a very compact structure in which the two acidic residues located on the top of a 'horse saddle' topology face each other, whereas the ionized form could adopt a more extended conformation. A common property of these compounds is their capacity to interact with lipids. The present structural data open the way for a further establishment of structure-activity relationships.

We tested the hypothesis that the bacterial load at the infection site could impact considerably on the pharmacokinetic/pharmacodynamic (PK/PD) parameters of fluoroquinolones. Using a rat lung infection model, we measured the influence of different marbofloxacin dosage regimens on selection of resistant bacteria after infection with a low (10 5 CFU) or a high (10 9 CFU) inoculum of Klebsiella pneumoniae . For daily fractionated doses of marbofloxacin, prevention of resistance occurred for an area-under-the-concentration-time-curve (AUC)/MIC ratio of 189 h for the low inoculum, whereas for the high inoculum, resistant-subpopulation enrichment occurred for AUC/MIC ratios up to 756 h. For the high-inoculum-infected rats, the AUC/MIC ratio, C max /MIC ratio, and time within the mutant selection window ( T MSW ) were not found to be effective predictors of resistance prevention upon comparison of fractionated and single administrations. An index corresponding to the ratio of the time that the drug concentrations were above the mutant prevention concentration (MPC) over the time that the drug concentrations were within the MSW ( T > MPC / T MSW ) was the best predictor of the emergence of resistance: a T > MPC / T MSW ratio of 0.54 was associated with prevention of resistance for both fractionated and single administrations. These results suggest that the enrichment of resistant bacteria depends heavily on the inoculum size at the start of an antimicrobial treatment and that classical PK/PD parameters cannot adequately describe the impact of different dosage regimens on enrichment of resistant bacteria. We propose an original index, the T > MPC / T MSW ratio, which reflects the ratio of the time that the less susceptible bacterial subpopulation is killed over the time that it is selected, as a potentially powerful indicator of prevention of enrichment of resistant bacteria. This ratio is valid only if plasma concentrations achieve the MPC.

Taxonomic revisions within the anuran family Ranidae have established the genus Lithobates that currently comprises 49 species of frogs from the New World. Peptidomic analysis, using reversed-phase HPLC with on-line detection by electrospray mass spectrometry, has led to the identification of multiple antimicrobial peptides in norepinephrine-stimulated skin secretions of the North American frog Lithobates capito and the Central American frog Lithobates warszewitschii . Structural characterization of the peptides demonstrated that the L. capito secretions contained brevinin-1 (1), esculentin-1 (1), esculentin-2 (1), ranatuerin-2 (3), and temporin (2) peptides. L. warszewitschii secretions contained brevinin-1 (1), esculentin-2 (1), ranatuerin-2 (2), and temporin (1) peptides. Values in parentheses indicate number of peptides in each family. Temporin-CPa from L. capito , with the atypical structure IPPFIKKVLTTVF·NH 2 , also showed atypical growth-inhibitory activity having greater potency against Escherichia coli (MIC = 25 μM) and Candida albicans (MIC = 25 μM) than against Staphylococcus aureus (MIC = 50 μM). Phylogenetic analysis based upon the amino acid sequences of 37 ranatuerin-2 peptides from 17 species belonging to the genus Lithobates provides support for currently accepted taxonomic relationships. L. capito is sister-group to Lithobates sevosus in a clade that also contains Lithobates areolatus , and Lithobates palustris . L. warszewitschii is most closely related to the Central American species Lithobates tarahumarae and Lithobates vaillanti .

International audience; The qnr genes are plasmid-borne fluoroquinolone-resistance determinants widespread in Enterobacteriaceae. Three families of qnr determinants (qnrA, B and S) have been described, but little is known about their expression and regulation. Two new determinants, qnrC and qnrD, have been found recently. Here, we describe the characterization of the qnrB2 promoter and the identification of a LexA-binding site in the promoter region of all qnrB alleles. LexA is the central regulator of the SOS response to DNA damage. We show that qnrB2 expression is regulated through the SOS response in a LexA/RecA-dependent manner, and that it can be induced by the quinolone ciprofloxacin, a known inducer of the SOS system. This is the first description of direct SOS-dependent regulation of an antibiotic-resistance mechanism in response to the antibiotic itself.

A broad variety of natural parabens, including four novel structures and known ethyl and butyl parabens, were obtained from culture of a Microbulbifer sp. bacterial strain isolated from the temperate calcareous marine sponge Leuconia nivea (Grant 1826). Their structures were elucidated from spectral analysis, including mass spectrometry and 1D and 2D nuclear magnetic resonance. Their antimicrobial activity evaluated against Staphylococcus aureus was characterized by much higher in vitro activity of these natural paraben compounds 3-9 than commercial synthetic methyl and propyl parabens, usually used as antimicrobial preservatives. Compounds 4 and 9 revealed a bacteriostatic effect and compounds 6 and 7 appeared as bactericidal compounds. Major paraben compound 6 was also active against Gram positive Bacillus sp. and Planococcus sp. sponge isolates and was detected in whole sponge extracts during all seasons, showing its persistent in situ production within the sponge. Moreover, Microbulbifer sp. bacteria were visualized in the sponge body wall using fluorescence in situ hybridization with a probe specific to L4-n2 phylotypes. Co-detection in the sponge host of both paraben metabolites and Microbulbifer sp. L4-n2 indicates, for the first time, production of natural parabens in a sponge host, which may have an ecological role as chemical mediators. © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.

International audience; Six structurally similar and strongly cationic peptides belonging to the brevinin-1 family were isolated from skin secretions of the plains leopard frog Lithobates blairi and the lowland leopard frog Lithobates yavapaiensis on the basis of their antimicrobial activities. Brevinin-1BLc (FLPIIAGIAAKFLPKIFCTISKKC) from L. blairi represented the most potent peptide (MIC=25microM Escherichia coli, MIC=1.5microM Staphylococcus aureus, MIC=3microM Candida albicans, LC(50)=9microM human erythrocytes and LC(50)=6microM HepG2 human hepatoma-derived cells). The appreciably lower antimicrobial potencies of brevinin-1Ya and -1Yc from L. yavapaiensis correlate with the decreases in cationicity produced by the amino acid substitutions Lys(11)-->Asn (brevinin-1Ya) and Pro(14)-->Glu (brevinin-1Yc). In addition, a peptide isolated from the skin secretions of L. yavapaiensis belonging to the ranatuerin-2 family (ranatuerin-2Ya; GLMDTIKGVAKTVAASWLDKLKCKIT GC) inhibited the growth of E. coli (MIC=50microM) and S. aureus (MIC=50microM). In contrast to brevinin-1BLc, ranatuerin-2Ya showed appreciably greater cytolytic activity against HepG2 cells (LC(50)=20microM) than against erythrocytes (LC(50)>100microM).

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International audience; During the past decade, major advances have reported the importance of the vitamin D on the bone metabolism, and recent studies have suggested the potential non skeletal effects of the vitamin D. Adequate vitamin D contributes to reduce the risk of non vertebral fractures, improves the neuromuscular function and reduces the risk of falls when serum 25OHD level are greater than 30ng/mL (75nmol/L). A possible role of vitamin D has been implicated in the reduction of mortality, of the non-skin cancers, of the risk of infections, of inflammatory diseases, of cardiovascular diseases and maybe osteoarthritis. However the current level of evidence for associations is weaker than for skeletal effects. Serum 25OHD level is influenced by several factors (cutaneous vitamin D production, fat mass, dietary sources, UV-B exposure, latitude, season...), and the measurement of the serum 25OHD level is the only way to determine the vitamin D status. It is recommended to measure the serum 25OHD level in patients with osteoporosis or at risk of osteoporosis, and to correct the deficiency.

International audience