Genotypic and phenotypic diversity in the noncapsulated Haemophilus infl uenzae: adaptation and pathogenesis in the human airways

The human respiratory tract contains a highly adapted microbiota including commensal and opportunistic pathogens. Noncapsulated or nontypable Haemophilus infl uenzae (NTHi) is a human-restricted member of the normal airway microbiota in healthy carriers and an opportunistic pathogen in immunocompromised individuals. The duality of NTHi as a colonizer and as a symptomatic infectious agent is closely related to its adaptation to the host, which in turn greatly relies on the genetic plasticity of the bacterium and is facilitated by its condition as a natural competent. The variable genotype of NTHi accounts for its heterogeneous gene expression and variable phenotype, leading to differential host-pathogen interplay among isolates. Here we review our current knowledge of NTHi diversity in terms of genotype, gene expression, antigenic variation, and the phenotypesassociated with colonization and pathogenesis. The potential benefi ts of NTHi diversity studies discussed herein include the unraveling of pathogenicity clues, the generation of tools to predict virulence from genomic data, and the exploitation of a unique natural system for the continuous monitoring of long-term bacterial evolution in human airways exposed to noxious agents. Finally, we highlight the challenge of monitoring both the pathogen and the host in longitudinal studies, and of applying comparative genomics to clarify the meaning of the vast NTHi genetic diversity and its translation to virulence phenotypes. [Int Microbiol 2012; 15(4): 157-170

Genotypic and phenotypic diversity in the noncapsulated Haemophilus infl uenzae: adaptation and pathogenesis in the human airways

The human respiratory tract contains a highly adapted microbiota including commensal and opportunistic pathogens. Noncapsulated or nontypable Haemophilus infl uenzae (NTHi) is a human-restricted member of the normal airway microbiota in healthy carriers and an opportunistic pathogen in immunocompromised individuals. The duality of NTHi as a colonizer and as a symptomatic infectious agent is closely related to its adaptation to the host, which in turn greatly relies on the genetic plasticity of the bacterium and is facilitated by its condition as a natural competent. The variable genotype of NTHi accounts for its heterogeneous gene expression and variable phenotype, leading to differential host-pathogen interplay among isolates. Here we review our current knowledge of NTHi diversity in terms of genotype, gene expression, antigenic variation, and the phenotypesassociated with colonization and pathogenesis. The potential benefi ts of NTHi diversity studies discussed herein include the unraveling of pathogenicity clues, the generation of tools to predict virulence from genomic data, and the exploitation of a unique natural system for the continuous monitoring of long-term bacterial evolution in human airways exposed to noxious agents. Finally, we highlight the challenge of monitoring both the pathogen and the host in longitudinal studies, and of applying comparative genomics to clarify the meaning of the vast NTHi genetic diversity and its translation to virulence phenotypes. [Int Microbiol 2012; 15(4): 157-170

Significance of tagl and mfd genes in the virulence of non-typeable Haemophilus infl uenzae

Non-typeable Haemophilus infl uenzae (NTHi) is an opportunist pathogen well adapted to the human upper respiratory tract and responsible for many respiratory diseases. In the human airway, NTHi is exposed to pollutants, such as alkylating agents, that damage its DNA. In this study, we examined the signifi cance of genes involved in the repair of DNA alkylation damage in NTHi virulence. Two knockout mutants, tagI and mfd, encoding N3methyladenine-DNA glycosylase I and the key protein involved in transcription-coupled repair, respectively, were constructed and their virulence in a BALB/c mice model was examined. This work shows that N3-methyladenine-DNA glycosylase I is constitutively expressed in NTHi and that it is relevant for its virulence. [Int Microbiol 2014; 17(3):159-164]Keywords: Haemophilus infl uenzae · alkylating agents · virulence · genes tagI and mf

Dissection of Host Cell Signal Transduction during Acinetobacter baumannii – Triggered Inflammatory Response

Infected airway epithelial cells up-regulate the expression of chemokines, chiefly IL-8, and antimicrobial molecules including β-defensins (BD). Acinetobacter baumannii is a cause of hospital-acquired pneumonia. We examined whether A. baumannii induced the expressions of IL-8 and BD2 by airway epithelial cells and the receptors implicated in bacterial detection. A549 and human primary airway cells released IL-8 upon infection. A. baumannii-infected cells also increased the expression of BD2 which killed A. baummannii strains. IL-8 induction was via NF-κB and mitogen-activated kinases p38 and p44/42-dependent pathways. A. baumannii engaged Toll-like receptor (TLR) 2 and TLR4 pathways and A549 cells could use soluble CD14 as TLRs co-receptor. A. baumannii lipopolysaccharide stimulated IL-8 release by A549 cells and sCD14 facilitated the recognition of the lipopolysaccharide. Mass spectrometry analysis revealed that A. baumannii lipid A structure matches those with endotoxic potential. These results demonstrate that airway epithelial cells produce mediators important for A. baumannii clearance

3D reconstruction of weeds using depth cameras

El objetivo de este estudio fue optimizar el ángulo de posicionamiento del sensor Kinect para la reconstrucción de la estructura tridimensional de Xanthium strumarium L., Datura stramonium L. y Chenopodium album L., utilizando para ello algoritmos que permiten la captura y combinación de imágenes de profundidad y RGB. Se han comparado diferentes ángulos, fijando en cada uno de ellos el sensor Kinect de forma estática respecto de la planta objetivo. Los resultados han confirmado la correlación entre la biomasa de malas hierbas y el área estimada con el sensor. La estimación de la altura de las plantas también fue adecuada, con una media de 2cm de error dependiendo de la posición del sensor. Sin embargo, aunque el sensor ha mostrado su capacidad para la creación de modelos tridimensionales, el adecuado posicionamiento del sensor es fundamental para la correcta reconstrucción de plantas. La posición ideal del sensor debe ser elegida de acuerdo a la especie a medir y su estado fenológico. Estos resultados sugieren que Kinect es una herramienta útil para caracterizar de forma rápida y fiable las malas hierbas, con importantes ventajas sobre otros sensores debido a su bajo coste, bajo requerimiento energético y alta frecuencia de transmisión de imágenes.The objective of this study was to optimize the positioning angle of a Kinect sensor for reconstructing the three dimensional structure of weeds, using Kinect fusion algorithms to generate a 3D point cloud from the depth video stream. The sensor was mounted in different positions facing the plant in order to obtain depth (RGB-D) images from different angles. The results confirmed the correlation between ground truth (e. g. weed biomass) and the measured area with Kinect. In addition, plant height was accurately estimated with a few centimeters error. However, although the Kinect sensor has shown its ability for plant reconstruction, proper positioning of the sensor is critical for correct reconstruction of plants. The best position of the sensor must be chosen according to the species to be measured and their growth stage. These results suggest that Kinect is a promising tool for a rapid and reliable weed characterization, with several important advantages such as low cost, low power requirement and a high frame rate

Formation of soy protein-based superabsorbent materials through optimization of a thermal processing

Superabsorbent materials are used in a wide range of products (e.g. personal care, controlled-release of nutrients in agriculture). The present study pretends the development of biodegradable materials from a natural source, a soy protein isolate, which eventually would help to diminish the environmental issues associated to the use of common synthetic materials. Moreover, the present work focuses on the modulation of the water uptake exclusively through the modification of the parameters of the thermal processes carried out during the development of those materials. Firstly, the protein isolate is blended with the plasticizer (glycerol) in a 1/1 ratio. Then, the homogeneous blend is injected using different mould temperatures and, subsequently, the bioplastics obtained are submitted to a dehydrothermal treatment (tdeshid) consisting on the storage of the samples at 50 ºC for a certain time (tdeshid). When the mould temperature is 70 ºC, superabsorbent materials are always obtained at tdeshid, shorter than 12 h. Conversely, viscoelastic properties increase as DHT treatment is longer, reducing the swelling that takes place during water absorption, and resulting more compact matrices. Thus, the present study proves how thermal processing modulation can solely determine the superabsorbent ability of soy protein-based biodegradable materials.Los materiales superabsorbentes son aplicables en campos tan diversos como productos de higiene personal o liberación controlada de nutrientes en agricultura. El presente estudio pretende el desarrollo de materiales biodegradables a partir de una materia prima natural, un aislado de proteína de soja, cuya aplicación supondría una disminución en el uso de materiales sintéticos, repercutiendo beneficiosamente en el medio ambiente; y la modulación de su capacidad de absorción de agua, que se modificará exclusivamente variando las condiciones de los procesos térmicos a los que son sometidas durante su obtención. En primer lugar, el aislado se mezcla con glicerina (plastificante)en una proporción 1/1, para después inyectar la masa homogénea utilizando diferentes temperaturas de moldeo (Tmold). Posteriormente, son sometidas a un tratamiento deshidrotérmico. o almacenamiento a 50ºC, durante cierto periodo de tiempo (tdeshid). Cuando la Tmold utilizada es 70ºC, se obtienen siempre materiales superabsorbentes, cuando el tdeshid seleccionado sea menos de 12h. Por otra parte, las propiedades viscoelásticas aumentan con la duración del tratamiento deshidrotérmico, provocando un menor hinchamiento durante la absorción de agua, resultando matrices menos porosas. Así, el presente estudio permite comprobar cómo modulando exclusivamente las condiciones de procesado pueden conseguirse capacidades superabsorbentes para materiales biodegradables basados en soja.Ministerio de Economía y Competitividad de España-CTQ2015-71164-

Identification and characterization of Klebsiella pneumoniae two lpxL lipid A late acyltransferases and their role in virulence

Klebsiella pneumoniae causes a wide range of infections, from urinary tract infections to pneumonia. The lipopolysaccharide is a virulence factor of this pathogen, although there are gaps in our understanding of its biosynthesis. Here we report on the characterization of K. pneumoniae lpxL, which encodes one of the enzymes responsible for the late secondary acylation of immature lipid A molecules. Analysis of the available K. pneumoniae genomes revealed that this pathogen's genome encodes two orthologues of Escherichia coli LpxL. Using genetic methods and mass spectrometry, we demonstrate that LpxL1 catalyzes the addition of laureate and LpxL2 catalyzes the addition of myristate. Both enzymes acylated E. coli lipid A, whereas only LpxL2 mediated K. pneumoniae lipid A acylation. We show that LpxL1 is negatively regulated by the two-component system PhoPQ. The lipid A produced by the lpxL2 mutant lacked the 2-hydroxymyristate, palmitate, and 4-aminoarabinose decorations found in the lipid A synthesized by the wild type. The lack of 2-hydroxymyristate was expected since LpxO modifies the myristate transferred by LpxL2 to the lipid A. The absence of the other two decorations is most likely caused by the downregulation of phoPQ and pmrAB expression. LpxL2-dependent lipid A acylation protects Klebsiella from polymyxins, mediates resistance to phagocytosis, limits the activation of inflammatory responses by macrophages, and is required for pathogen survival in the wax moth (Galleria mellonella). Our findings indicate that the LpxL2 contribution to virulence is dependent on LpxO-mediated hydroxylation of the LpxL2-transferred myristate. Our studies suggest that LpxL2 might be a candidate target in the development of anti-K. pneumoniae drugs

A Klebsiella pneumoniae antibiotic resistance mechanism that subdues host defences and promotes virulence

Klebsiella pneumoniae is an important cause of multidrug-resistant infections worldwide. Recent studies highlight the emergence of multidrug-resistant K.\ua0pneumoniae strains which show resistance to colistin, a last-line antibiotic, arising from mutational inactivation of the mgrB regulatory gene. However, the precise molecular resistance mechanisms of mgrB-associated colistin resistance and its impact on virulence remain unclear. Here, we constructed an mgrB gene K.\ua0pneumoniae mutant and performed characterisation of its lipid A structure, polymyxin and antimicrobial peptide resistance, virulence and inflammatory responses upon infection. Our data reveal that mgrB mutation induces PhoPQ-governed lipid A remodelling which confers not only resistance to polymyxins, but also enhances K. pneumoniae virulence by decreasing antimicrobial peptide susceptibility and attenuating early host defence response activation. Overall, our findings have important implications for patient management and antimicrobial stewardship, while also stressing antibiotic resistance development is not inexorably linked with subdued bacterial fitness and virulence