126 research outputs found
Infections of implantable cardiac devices by biofilm forming bacteria in western Algeria hospitals
Background: The significant increase in the use of implantable cardiac devices (ICDs) has been accompanied by biofilm formation and increase rate of infection on the devices. The purpose of our study is to describe the clinical and microbiological findings of infection of ICDs in the cardiology units of western Algeria hospitals.
Methodology: All patients with clinical diagnosis of ICD infections or infective endocarditis upon removal of their ICDs from December 2012 to August 2014 in cardiology units of 4 Algerian hospitals were included in the study. Each element of the ICD pocket and lead was separately sonicated in sterile saline, inoculated onto Chapman and MacConkey agar plates and incubated aerobically at 37oC for colony count after 24 hours. Biochemical identification of the bacteria isolates was made by API 20E, API 20 NE and API Staph, and confirmed by Siemens Healthcare Diagnostics WalkAwayÂź 96 Plus System. Antibiotic susceptibility testing on each isolate was performed by the disk diffusion method on Mueller Hinton agar. Biofilm formation was detected by Congo Red Agar (CRA) and Tissue Culture Plate (TCP) methods, and hydrophobicity of the bacterial cell was determined by the MATH protocol.
Results: Over a period of twenty-one months, 17 ICDs were removed from patients with post-operative infections; 6 (35.3%) had early infection of ICD and 11 (64.7%) had late ICD infection. Fifty-four bacterial strains were isolated and identified, with coagulase-negative staphylococci being the predominant bacteria with 46.3% (25/54). There was no significant association between hydrophobicity and antimicrobial resistance in the 54 isolates but there is positive correlation between biofilm production and antimicrobial resistance, with the strongest biofilm producers resistant to more than one antibiotic. Four independent predictors of infection of resynchronization devices were reported; reoperation, multi-morbidity, long procedure, and ICD implantation.
Conclusion: Our study is the first in Algeria to describe microbiological characteristics of ICD infection. The bacteria in the biofilm were protected, more resistant and tolerated high concentrations of antibiotics and thus played a major role in the development of ICD infections. Despite the improvements in ICD design and implantation techniques, ICD infection remains a serious challenge.
Keywords: implantable cardiac devices, staphylococci, resistance, biofilm, hydrophobicity
French title: Infections des dispositifs cardiaques implantables par des bactéries formant un biofilm dans les hÎpitaux de l'ouest Algérien
Contexte: L'augmentation significative de l'utilisation des dispositifs cardiaques implantables est un risque majeur d'augmentation du taux d'infection et donc du risque de formation d'un biofilm sur ce genre de dispositifs. L'objectif de notre étude est de décrire les résultats cliniques et microbiologiques de l'infection sur les dispositifs cardiaques implantables (DCI) dans les unités de cardiologie des hÎpitaux de l'ouest Algérien.
Méthodologie: Tous les patients cliniquement diagnostiqués avec une infection sur DCI, ou une endocardite infectieuse et ayant subit un retrait de leur dispositif cardiaque sont inclus dans cette étude et cela sur une période entre décembre 2012 et aout 2014 dans 4 unités de cardiologie. Chaque élément du DCI (boitier et sonde) est trempé séparément dans une solution saline stérile, ensemencé sur deux milieux de culture, un milieu de Chapman et un milieu MacConkey et incubé en aérobiose à 37°C pour la numération des colonies aprÚs 24 heures. L'identification biochimique des isolats de bactéries est effectuée par le API 20E, API 20 NE et API Staph, et confirmée par le systÚme WalkAwayŸ 96 Plus de Siemens Healthcare Diagnostics. Les tests de sensibilité aux antibiotiques de chaque isolat sont effectués par la méthode de diffusion des disques sur gélose de Mueller Hinton. La formation d'un biofilm est détectée par les méthodes de la gélose rouge du Congo (CRA) et de la plaque de culture tissulaire (TCP), et l'hydrophobicité de la cellule bactérienne est déterminée par le protocole MATH.
RĂ©sultats: Sur une pĂ©riode de 21 mois, 17 DCI sont retirĂ©s de patients atteints d'infections postopĂ©ratoires; 6 patients (35,3%) sont identifiĂ©s comme ayant une infection prĂ©coce sur leurs DCI et 11 patients (64,7%) ayant une infection tardive. Cinquante-quatre souches bactĂ©riennes sont isolĂ©es et identifiĂ©es, les staphylocoques Ă coagulase nĂ©gative Ă©tant les bactĂ©ries prĂ©dominantes avec 46,3% (25/54). Il n'y a pas d'association significative entre l'hydrophobicitĂ© et la rĂ©sistance aux antimicrobiens dans les 54 isolats, mais il existe une corrĂ©lation positive entre la production de biofilm et la rĂ©sistance aux antimicrobiens, les plus puissants en biofilm sont rĂ©sistant Ă plus d'un antibiotique. Quatre facteurs prĂ©dictifs indĂ©pendants dâinfection des dispositifs cardiaques implantable sont retrouvĂ©s dans ce travail: rĂ©-intervention, longue procĂ©dure, sujets multi-tarĂ©s, et implantation dâun DCI
Conclusion: Notre étude est la premiÚre en Algérie à décrire les caractéristiques microbiologiques de l'infection des DCI. Les bactéries présentes dans le biofilm sont protégées, plus résistantes et tolÚrent de fortes concentrations d'antibiotiques et jouent ainsi un rÎle majeur dans le développement des infections par DCI. Malgré des améliorations dans les techniques de conception et d'implantation de DCI, l'infection des dispositifs cardiaques implantables reste un problÚme grave et trÚs couteux.
Mots-clés: dispositifs cardiaques implantables; staphylocoque; résistance; biofilm; hydrophobicit
Unified Framework for Development, Deployment and Robust Testing of Neuroimaging Algorithms
Developing both graphical and commandline user interfaces for neuroimaging algorithms requires considerable effort. Neuroimaging algorithms can meet their potential only if they can be easily and frequently used by their intended users. Deployment of a large suite of such algorithms on multiple platforms requires consistency of user interface controls, consistent results across various platforms and thorough testing.
We present the design and implementation of a novel object-oriented framework that allows for rapid development of complex image analysis algorithms with many reusable components and the ability to easily add graphical user interface controls. Our framework also allows for simplified yet robust nightly testing of the algorithms to ensure stability and cross platform interoperability. All of the functionality is encapsulated into a software object requiring no separate source code for user interfaces, testing or deployment. This formulation makes our framework ideal for developing novel, stable and easy-to-use algorithms for medical image analysis and computer assisted interventions. The technological The framework has been both deployed at Yale and released for public use in the open source multi-platform image analysis software - BioImage Suite (bioimagesuite.org)
The Continuous Hidden Threshold Mixed Skew-Symmetric Distribution
This paper explores a way to construct a new family of univariate probability distributions where the
parameters of the distribution capture the dependence between the variable of interest and the continuous
latent state variable (the regime). The distribution nests two well known families of distributions, namely,
the skew normal family of Azzalini (1985) and a mixture of two Arnold et al. (1993) distribution. We
provide a stochastic representation of the distribution which enables the user to easily simulate the data
from the underlying distribution using generated uniform and normal variates. We also derive the moment
generating function and the moments. The distribution comprises eight free parameters that make it very
flexible. This flexibility allows the user to capture many stylized facts about the data such as the regime
dependence, the asymmetry and fat tails as well as thin tails
The Continuous Hidden Threshold Mixed Skew-Symmetric Distribution
This paper explores a way to construct a new family of univariate probability distributions where the
parameters of the distribution capture the dependence between the variable of interest and the continuous
latent state variable (the regime). The distribution nests two well known families of distributions, namely,
the skew normal family of Azzalini (1985) and a mixture of two Arnold et al. (1993) distribution. We
provide a stochastic representation of the distribution which enables the user to easily simulate the data
from the underlying distribution using generated uniform and normal variates. We also derive the moment
generating function and the moments. The distribution comprises eight free parameters that make it very
flexible. This flexibility allows the user to capture many stylized facts about the data such as the regime
dependence, the asymmetry and fat tails as well as thin tails
The Continuous Hidden Threshold Mixed Skew-Symmetric Distribution
This paper explores a way to construct a new family of univariate probability distributions where the
parameters of the distribution capture the dependence between the variable of interest and the continuous
latent state variable (the regime). The distribution nests two well known families of distributions, namely,
the skew normal family of Azzalini (1985) and a mixture of two Arnold et al. (1993) distribution. We
provide a stochastic representation of the distribution which enables the user to easily simulate the data
from the underlying distribution using generated uniform and normal variates. We also derive the moment
generating function and the moments. The distribution comprises eight free parameters that make it very
flexible. This flexibility allows the user to capture many stylized facts about the data such as the regime
dependence, the asymmetry and fat tails as well as thin tails
Density, speed of sound and refractive index of mixtures containing 2-phenoxyethanol with propanol or butanol at various temperatures
In this work, we reported the new experimental data of densities, speeds of sound, and refractive indices for four binary mixtures: {2-phenoxyethanol (2PhEE)âŻ+âŻ1-propanol or 2-propanol or 1-butanol or 2-butanol) over the entire composition range and at temperatures of (293.15, 303.15, 313.15 and 323.15)âŻK and at pressure pâŻ=âŻ0.1âŻMPa. From these experimental data, thermodynamics properties: excess molar volume, isentropic compressibility, deviation in isentropic compressibility and deviation in refractive indices were calculated. Excess molar volume, deviation in isentropic compressibility and deviation in refractive indices data have been correlated using the RedlichâKister equation. From the obtained results, a discussion was carried out in terms of nature of intermolecular interactions and structure factors in these binary mixtures
DNA Renaturation at the Water-Phenol Interface
We study DNA adsorption and renaturation in a water-phenol two-phase system,
with or without shaking. In very dilute solutions, single-stranded DNA is
adsorbed at the interface in a salt-dependent manner. At high salt
concentrations the adsorption is irreversible. The adsorption of the
single-stranded DNA is specific to phenol and relies on stacking and hydrogen
bonding. We establish the interfacial nature of a DNA renaturation at a high
salt concentration. In the absence of shaking, this reaction involves an
efficient surface diffusion of the single-stranded DNA chains. In the presence
of a vigorous shaking, the bimolecular rate of the reaction exceeds the
Smoluchowski limit for a three-dimensional diffusion-controlled reaction. DNA
renaturation in these conditions is known as the Phenol Emulsion Reassociation
Technique or PERT. Our results establish the interfacial nature of PERT. A
comparison of this interfacial reaction with other approaches shows that PERT
is the most efficient technique and reveals similarities between PERT and the
renaturation performed by single-stranded nucleic acid binding proteins. Our
results lead to a better understanding of the partitioning of nucleic acids in
two-phase systems, and should help design improved extraction procedures for
damaged nucleic acids. We present arguments in favor of a role of phenol and
water-phenol interface in prebiotic chemistry. The most efficient renaturation
reactions (in the presence of condensing agents or with PERT) occur in
heterogeneous systems. This reveals the limitations of homogeneous approaches
to the biochemistry of nucleic acids. We propose a heterogeneous approach to
overcome the limitations of the homogeneous viewpoint
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