118 research outputs found
Detection of colistin resistance in Salmonella enterica using MALDIxin test on the routine MALDI Biotyper Sirius mass spectrometer
Resistance to polymyxins in most Gram-negative bacteria arises from chemical modifications to the lipid A portion of their lipopolysaccharide (LPS) mediated by chromosomally-encoded mutations or the recently discovered plasmid-encoded mcr genes that have further complicated the landscape of colistin resistance. Currently, minimal inhibitory concentration (MIC) determination by broth microdilution, the gold standard for the detection of polymyxin resistance, is time consuming (24 hours) and challenging to perform in clinical and veterinatryveterinary laboratories. Here we present the use of the MALDIxin to detect colistin resistant Salmonella enterica using the MALDxin test on the routine matrix-assisted laser desorption ionization (MALDI) Biotyper Sirius system
Perception of Nigerian DĂčndĂșn talking drum performances as speech-like vs. music-like: The role of familiarity and acoustic cues
It seems trivial to identify sound sequences as music or speech, particularly when the sequences come from different sound sources, such as an orchestra and a human voice. Can we also easily distinguish these categories when the sequence comes from the same sound source? On the basis of which acoustic features? We investigated these questions by examining listenersâ classification of sound sequences performed by an instrument intertwining both speech and music: the dĂčndĂșn talking drum. The dĂčndĂșn is commonly used in south-west Nigeria as a musical instrument but is also perfectly fit for linguistic usage in what has been described as speech surrogates in Africa. One hundred seven participants from diverse geographical locations (15 different mother tongues represented) took part in an online experiment. Fifty-one participants reported being familiar with the dĂčndĂșn talking drum, 55% of those being speakers of YorĂčbĂĄ. During the experiment, participants listened to 30 dĂčndĂșn samples of about 7s long, performed either as music or YorĂčbĂĄ speech surrogate (n = 15 each) by a professional musician, and were asked to classify each sample as music or speech-like. The classification task revealed the ability of the listeners to identify the samples as intended by the performer, particularly when they were familiar with the dĂčndĂșn, though even unfamiliar participants performed above chance. A logistic regression predicting participantsâ classification of the samples from several acoustic features confirmed the perceptual relevance of intensity, pitch, timbre, and timing measures and their interaction with listener familiarity. In all, this study provides empirical evidence supporting the discriminating role of acoustic features and the modulatory role of familiarity in teasing apart speech and music
The DĂčndĂșn Drum helps us understand how we process speech and music
Every day, you hear many sounds in your environment, like speech, music, animal calls, or passing cars. How do you tease apart these unique categories of sounds? We aimed to understand more about how people distinguish speech and music by using an instrument that can both âspeakâ and play music: the dĂčndĂșn talking drum. We were interested in whether people could tell if the sound produced by the drum was speech or music. People who were familiar with the dĂčndĂșn were good at the task, but so were those who had never heard the dĂčndĂșn, suggesting that there are general characteristics of sound that define speech and music categories. We observed that music is faster, more regular, and more variable in volume than âspeech.â This research helps us understand the interesting instrument that is dĂčndĂșn and provides insights about how humans distinguish two important types of sound: speech and music
Two-site study on performances of a commercially available MALDI-TOF MS-based assay for the detection of colistin resistance in Escherichia coli
Colistin is a last resort drug for the treatment of multiple drug-resistant (MDR) Gram-negative bacterial infections. Rapid methods to detect resistance are highly desirable. Here, we evaluated the performance of a commercially available MALDI-TOF MS-based assay for colistin resistance testing in Escherichia coli at two different sites. Ninety clinical E. coli isolates were provided by France and tested in Germany and UK using a MALDI-TOF MS-based colistin resistance assay. Lipid A molecules of the bacterial cell membrane were extracted using the MBT Lipid Xtract Kitâą (RUO; Bruker Daltonics, Germany). Spectra acquisition and evaluation were performed by the MBT HT LipidART Module of MBT Compass HT (RUO; Bruker Daltonics) on a MALDI BiotyperÂź sirius system (Bruker Daltonics) in negative ion mode. Phenotypic colistin resistance was determined by broth microdilution (MICRONAUT MIC-Strip Colistin, Bruker Daltonics) and used as a reference. Comparing the results of the MALDI-TOF MS-based colistin resistance assay with the data of the phenotypic reference method for the UK, sensitivity and specificity for the detection of colistin resistance were 97.1% (33/34) and 96.4% (53/55), respectively. Germany showed 97.1% (33/34) sensitivity and 100% (55/55) specificity for the detection of colistin resistance by MALDI-TOF MS. Applying the MBT Lipid Xtractâą Kit in combination with MALDI-TOF MS and dedicated software showed excellent performances for E. coli. Analytical and clinical validation studies must be performed to demonstrate the performance of the method as a diagnostic tool
Preparation of Long-Lived, Non-Autoionizing Circular Rydberg States of Strontium
Alkaline earth Rydberg atoms are very promising tools for quantum
technologies. Their highly excited outer electron provides them with the
remarkable properties of Rydberg atoms and, notably, with a huge coupling to
external fields or to other Rydberg atoms while the ionic core retains an
optically active electron. However, low angular-momentum Rydberg states suffer
almost immediate autoionization when the core is excited. Here, we demonstrate
that strontium circular Rydberg atoms with a core excited in a metastable
level are impervious to autoionization over more than a few millisecond time
scale. This makes it possible to trap and laser-cool Rydberg atoms. Moreover,
we observe singlet to triplet transitions due to the core optical
manipulations, opening the way to a quantum microwave to optical interface
Optimization of the MALDIxin test for the rapid identification of colistin resistance in Klebsiella pneumoniae using MALDI-TOF-MS
Background. With the dissemination of carbapenemase producers, a revival of colistin was observed for the treatment of infections caused by multidrug-resistant Gram-negatives. Unfortunately, the increasing usage of colistin led to the emergence of resistance. In Klebsiella pneumoniae, colistin resistance arises through addition of L-arabinose-4N (L-Ara4N) or phosphoethanolamine (pEtN) on the native lipid A. The underlying mechanisms involve numerous chromosome-encoded genes or the plasmid-encoded phosphoethanolamine transferase MCR. Currently, detection of colistin resistance is time consuming since it still relies on MIC determination by broth microdilution. Recently, a rapid diagnostic test based on MALDI-TOF detection of modified lipid A was developed (the MALDIxin test) and tested on Escherichia coli and Acinetobacter baumannii. Objectives. Optimize the MALDIxin test for the rapid detection of colistin resistance in Klebsiella pneumoniae. Methods. This optimization consists on an additional mild-acid hydrolysis of 15 min in 1% acetic acid. The optimized method was tested on a collection of 81 clinical K. pneumoniae isolates including 49 colistin resistant strains among which 45 correspond to chromosome-encoded resistance, 3 MCR-related resistance and one isolate harbouring both mechanisms. Results. The optimized method allowed the rapid (< 30 min) identification of L-Ara4N and pEtN modified lipid A of K. pneumoniae which are known to be the real triggers of polymyxin resistance. In the same time, it discriminates between chromosome-encoded and MCR-related polymyxin resistance. Conclusions. The MALDIxin test has the potential to become an accurate tool for the rapid diagnostic of colistin resistance in clinically-relevant Gram negative bacteria
Genetic diversity and dynamics of the Noir Marron settlement in French Guyana : A study combining mitochondrial DNA, Y chromosome and HTLV-1 genotyping [Abstract]
The Noir Marron are the direct descendants of thousands of African slaves deported to the Guyanas during the Atlantic Slave Trade and later escaped mainly from Dutch colonial plantations. Six ethnic groups are officially recognized, four of which are located in French Guyana: the Aluku, the Ndjuka, the Saramaka, and the Paramaka. The aim of this study was: (1) to determine the Noir Marron settlement through genetic exchanges with other communities such as Amerindians and Europeans; (2) to retrace their origins in Africa. Buffy-coat DNA from 142 Noir Marron, currently living in French Guyana, were analyzed using mtDNA (typing of SNP coding regions and sequencing of HVSI/II) and Y chromosomes (typing STR and SNPs) to define their genetic profile. Results were compared to an African database composed by published data, updated with genotypes of 82 Fon from Benin, and 128 Ahizi and 63 Yacouba from the Ivory-Coast obtained in this study for the same markers. Furthermore, the determination of the genomic subtype of HTLV-1 strains (env gp21 and LTR regions), which can be used as a marker of migration of infected populations, was performed for samples from 23 HTLV-1 infected Noir Marron and compared with the corresponding database. MtDNA profiles showed a high haplotype diversity, in which 99% of samples belonged to the major haplogroup L, frequent in Africa. Each haplotype was largely represented on the West African coast, but notably higher homologies were obtained with the samples present in the Gulf of Guinea. Y Chromosome analysis revealed the same pattern, i.e. a conservation of the African contribution to the Noir Marron genetic profile, with 98% of haplotypes belonging to the major haplogroup E1b1a, frequent in West Africa. The genetic diversity was higher than those observed in African populations, proving the large Noir Marronâs fatherland, but a predominant identity in the Gulf of Guinea can be suggested. Concerning HTLV-1 genotyping, all the Noir Marron strains belonged to the large Cosmopolitan A subtype. However, among them 17/23 (74%) clustered with the West African clade comprizing samples originating from Ivory-Coast, Ghana, Burkina-Fasso and Senegal, while 3 others clustered in the Trans-Sahelian clade and the remaining 3 were similar to strains found in individuals in South America. Through the combined analyses of three approaches, we have provided a conclusive image of the genetic profile of the Noir Marron communities studied. The high degree of preservation of the African gene pool contradicts the expected gene flow that would correspond to the major cultural exchanges observed between Noir Marron, Europeans and Amerindians. Marital practices and historical events could explain these observations. Corresponding to historical and cultural data, the origin of the ethnic groups is widely dispatched throughout West Africa. However, all results converge to suggest an individualization from a major birthplace in the Gulf of Guinea
The antibiotic bedaquiline activates host macrophage innate immune resistance to bacterial infection
Antibiotics are widely used in the treatment of bacterial infections. Although known for their microbicidal activity, antibiotics may also interfere with the host's immune system. Here, we analyzed the effects of bedaquiline (BDQ), an inhibitor of the mycobacterial ATP synthase, on human macrophages. Genome-wide gene expression analysis revealed that BDQ reprogramed cells into potent bactericidal phagocytes. We found that 579 and 1,495 genes were respectively differentially expressed in naive- and M. tuberculosis-infected macrophages incubated with the drug, with an over-representation of lysosome-associated genes. BDQ treatment triggered a variety of antimicrobial defense mechanisms, including phagosome-lysosome fusion, and autophagy. These effects were associated with activation of transcription factor EB, involved in the transcription of lysosomal genes, resulting in enhanced intracellular killing of different bacterial species that were naturally insensitive to BDQ. Thus, BDQ could be used as a host-directed therapy against a wide range of bacterial infections
NĂvel e natureza do estoque orgĂąnico de Latossolos sob diferentes sistemas de uso e manejo.
O papel fundamental da matĂ©ria orgĂąnica (MO) justifica o crescente interesse pela identificação de sistemas de uso e manejo que melhorem o estoque orgĂąnico em solos tropicais. O objetivo deste trabalho foi analisar variaçÔes quantitativas e qualitativas da MO e caracterizar compartimentos orgĂąnicos em um Latossolo Vermelho-Escuro argiloso sob vegetação natural antropizada (CER), pastagem de longa duração (PAL), pastagem degradada (PAD), e pousio (PAC), comparados com culturas sob preparo convencional (CCL) e plantio direto (PD). Foi encontrada pouca variação dos estoques orgĂąnicos na camada superficial, explicada pela antropização da vegetação em CER, pela nĂŁo-exportação dos resĂduos em PD e CCL e pela prĂĄtica de pousio em PAC. Fracionamento granulomĂ©trico, considerando os compartimentos resĂduos vegetais (20-2.000 ”m), organo-siltoso (2-20 ”m) e organo-argiloso (0-2 ”m), mostrou diferenças na qualidade da MO quando comparadas situaçÔes edafoambientais semelhantes. Mesmo com pequenas variaçÔes, o compartimento resĂduos vegetais foi um indicador da evolução dos estoques orgĂąnicos, permitindo a caracterização da degradação nas pastagens e do efeito do plantio direto, quando comparado ao sistema convencional. PD favoreceu a estocagem de C no compartimento organo-argiloso. Solos estudados diferem de outros solos argilosos tropicais pela mais elevada relação C/N encontrada nas fraçÔes 0-20 ”m
- âŠ