Single-cell scattering and auto-fluorescence-based fast antibiotic susceptibility testing for gram-negative and gram-positive bacteria

In this study, we assess the scattering of light and auto-fluorescence from single bacterial cells to address the challenge of fast (<2 h), label-free phenotypic antimicrobial susceptibility testing (AST). Label-free flow cytometry is used for monitoring both the respiration-related auto-fluorescence in two different fluorescence channels corresponding to FAD and NADH, and the morphological and structural information contained in the light scattered by individual bacteria during incubation with or without antibiotic. Large multi-parameter data are analyzed using dimensionality reduction methods, based either on a combination of 2D binning and Principal Component Analysis, or with a one-class Support Vector Machine approach, with the objective to predict the Susceptible or Resistant phenotype of the strain. For the first time, both Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram-positive) isolates were tested with a label-free approach, and, in the presence of two groups of bactericidal antibiotic molecules, aminoglycosides and beta-lactams. Our results support the feasibility of label-free AST in less than 2 h and suggest that single cell auto-fluorescence adds value to the Susceptible/Resistant phenotyping over single-cell scattering alone, in particular for the mecA+ Staphylococcus (i.e., resistant) strains treated with oxacillin

The Mayer-Rokitansky-Küster-Hauser syndrome (congenital absence of uterus and vagina) – phenotypic manifestations and genetic approaches

The Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome affects at least 1 out of 4500 women and has for a long time been considered as a sporadic anomaly. Congenital absence of upper vagina and uterus is the prime feature of the disease which, in addition, is often found associated with unilateral renal agenesis or adysplasia as well as skeletal malformations (MURCS association). The phenotypic manifestations of MRKH overlap various other syndromes or associations and thus require accurate delineation. Since MRKH manifests itself in males, the term GRES syndrome (Genital, Renal, Ear, Skeletal) might be more appropriate when applied to both sexes. The MRKH syndrome, when described in familial aggregates, seems to be transmitted as an autosomal dominant trait with an incomplete degree of penetrance and variable expressivity. This suggests the involvement of either mutations in a major developmental gene or a limited chromosomal deletion. Until recently progress in understanding the genetics of MRKH syndrome has been slow, however, now HOX genes have been shown to play key roles in body patterning and organogenesis, and in particular during genital tract development. Expression and/or function defects of one or several HOX genes may account for this syndrome

Impact des laisses végétales sur la dynamique des plages sableuses, Martinique, Petites Antilles

Les plages des Antilles sont régulièrement concernées par des échouages de laisses de mer végétales (algues, phanérogames…) qui viennent se mélanger en haut de plage au sable, au bois mort et autres déchets d’origine anthropique. Cette situation est renforcée depuis 2011 par de massifs échouages d’algues sargasses, qui réduisent significativement l’accès à la mer et produisent des émanations de gaz nocifs. Cette situation est préjudiciable pour l’économie des îles antillaises lourdement dépendantes du tourisme. Ces dépôts jouent également un rôle complexe sur la dynamique sédimentaire des plages par des facteurs de piégeage ou, à l’inverse, de remobilisation des sables. Les laisses végétales sont-elles des facteurs de renforcement de l’érosion des plages ou contribuent-elles, au contraire, à leur engraissement? Quels sont les impacts des ramassages manuels ou mécaniques de ces laisses sur le bilan sédimentaire et la dynamique des plages? Pour tenter de répondre à ces questions, une expérimentation in-situ a été réalisée sur les plages de l’Anse Caffard (Le Diamant) et l’Anse au Bois (Ste Anne) en Martinique. La plage de poche de l’Anse au Bois a été divisée en trois tronçons. Un premier, concerné par un ramassage total des laisses ; un second avec un épandage des échouages végétaux ; un troisième à l’état naturel, sans ramassage. Des mesures topographiques et hydrodynamiques ont été réalisées sur les trois secteurs afin de caractériser la réaction sédimentaire de la plage face à ces trois méthodes de gestion des échouages. Des mesures ont également été réalisées sur la plage de l’Anse Cafard, concernée par un ramassage mécanique. Ces expérimentations montrent des tendances morphodynamiques qu’il sera nécessaire de prendre en compte dans le cadre de la gestion des crises d’échouages d’algues sargasses.The beaches of the Caribbean Islands are regularly affected by the stranding of plant debris (algae, phanerogams, etc.) at the tide mark line, which becomes mixed with sand at the top of the beach, along with deadwood and other waste of anthropogenic origin. This situation has worsened since 2011 as a result of the stranding of sargassum seaweed, which significantly reduces beach access and produces emanations of harmful gases. This is damaging for the Caribbean islands of the Lesser Antilles, since their economies are heavily dependant on tourism. These deposits also play a complex role in the sedimentary dynamics of beaches by favouring the trapping or, alternatively, the re-mobilization of sands. Does this accumulation of drift reinforce the erosion of beaches or, on the contrary, does it contribute to their growth? What are the impacts of the manual or mechanical collection of these drift materials on the sediment budget and dynamics of beaches? In an attempt to address these questions, an in-situ experimental study was carried out on the beaches of the Anse Caffard (Le Diamant) and the Anse au Bois (Sainte-Anne) on Martinique. The pocket beach of the Anse au Bois was divided into three sectors. In the first sector, the drift was completely removed by collection, while a second sector was treated by spreading the stranded debris and a third sector was left in a natural state, without any collection. Topographic and hydrodynamic measurements were carried out on the three sectors to characterize the sedimentary response of the beach according to these three methods of managing the stranded drift. Measurements were also carried out on the Anse Caffard beach, which was managed by mechanical collection. These experiments reveal morphodynamic trends which need to be taken into account in the framework of the management of sargassum seaweed crises

Impact of seaweeds on sandy beaches morphodynamics, Martinique, Lesser Antilles

International audienc

Impact des laisses végétales sur la dynamique des plages sableuses, Martinique, Petites Antilles

The beaches of the Caribbean Islands are regularly affected by the stranding of plant debris (algae, phanerogams, etc.) at the tide mark line, which becomes mixed with sand at the top of the beach, along with deadwood and other waste of anthropogenic origin. This situation has worsened since 2011 as a result of the stranding of sargassum seaweed, which significantly reduces beach access and produces emanations of harmful gases. This is damaging for the Caribbean islands of the Lesser Antilles, since their economies are heavily dependant on tourism. These deposits also play a complex role in the sedimentary dynamics of beaches by favouring the trapping or, alternatively, the re-mobilization of sands. Does this accumulation of drift reinforce the erosion of beaches or, on the contrary, does it contribute to their growth? What are the impacts of the manual or mechanical collection of these drift materials on the sediment budget and dynamics of beaches? In an attempt to address these questions, an in-situ experimental study was carried out on the beaches of the Anse Caffard (Le Diamant) and the Anse au Bois (Sainte-Anne) on Martinique. The pocket beach of the Anse au Bois was divided into three sectors. In the first sector, the drift was completely removed by collection, while a second sector was treated by spreading the stranded debris and a third sector was left in a natural state, without any collection. Topographic and hydrodynamic measurements were carried out on the three sectors to characterize the sedimentary response of the beach according to these three methods of managing the stranded drift. Measurements were also carried out on the Anse Caffard beach, which was managed by mechanical collection. These experiments reveal morphodynamic trends which need to be taken into account in the framework of the management of sargassum seaweed crises

Fast Raman single bacteria identification: toward a routine in-vitro diagnostic

Conference on Biophotonics - Photonic Solutions for Better Health Care V, Brussels, BELGIUM, APR 04-07, 2016International audienceTimely microbiological results are essential to allow clinicians to optimize the prescribed treatment, ideally at the initial stage of the therapeutic process. Several approaches have been proposed to solve this issue and to provide the microbiological result in a few hours directly from the sample such as molecular biology. However fast and sensitive those methods are not based on single phenotypic information which presents several drawbacks and limitations. Optical methods have the advantage to allow single-cell sensitivity and to probe the phenotype of measured cells. Here we present a process and a prototype that allow automated single bacteria phenotypic analysis. This prototype is based on the use of Digital In-line Holography techniques combined with a specially designed Raman spectrometer using a dedicated device to capture bacteria. The localization of single-cell is finely determined by using holograms and a proper propagation kernel. Holographic images are also used to analyze bacteria in the sample to sort potential pathogens from flora dwelling species or other biological particles. This accurate localization enables the use of a small confocal volume adapted to the measurement of single-cell. Along with the confocal volume adaptation, we also have modified every components of the spectrometer to optimize single-bacteria Raman measurements. This optimization allowed us to acquire informative single-cell spectra using an integration time of 0.5s only. Identification results obtained with this prototype are presented based on a 65144 Raman spectra database acquired automatically on 48 bacteria strains belonging to 8 species