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1.
J Antimicrob Chemother ; 76(3): 587-595, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33338207

RESUMO

OBJECTIVES: To measure the variability in carbapenem susceptibility conferred by different OxaAb variants, characterize the molecular evolution of oxaAb and elucidate the contribution of OxaAb and other possible carbapenem resistance factors in the clinical isolates using WGS and LC-MS/MS. METHODS: Antimicrobial susceptibility tests were performed on 10 clinical Acinetobacter baumannii isolates. Carbapenem MICs were evaluated for all oxaAb variants cloned into A. baumannii CIP70.10 and BM4547, with and without their natural promoters. Molecular evolution analysis of the oxaAb variants was performed using FastTree and SplitsTree4. Resistance determinants were studied in the clinical isolates using WGS and LC-MS/MS. RESULTS: Only the OxaAb variants with I129L and L167V substitutions, OxaAb(82), OxaAb(83), OxaAb(107) and OxaAb(110) increased carbapenem MICs when expressed in susceptible A. baumannii backgrounds without an upstream IS element. Carbapenem resistance was conferred with the addition of their natural upstream ISAba1 promoter. LC-MS/MS analysis on the original clinical isolates confirmed overexpression of the four I129L and L167V variants. No other differences in expression levels of proteins commonly associated with carbapenem resistance were detected. CONCLUSIONS: Elevated carbapenem MICs were observed by expression of OxaAb variants carrying clinically prevalent substitutions I129L and L167V. To drive carbapenem resistance, these variants required overexpression by their upstream ISAba1 promoter. This study clearly demonstrates that a combination of IS-driven overexpression of oxaAb and the presence of particular amino acid substitutions in the active site to improve carbapenem capture is key in conferring carbapenem resistance in A. baumannii and other mechanisms are not required.


Assuntos
Acinetobacter baumannii , Proteínas de Bactérias , beta-Lactamases , Acinetobacter baumannii/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Cromatografia Líquida , Farmacorresistência Bacteriana , Testes de Sensibilidade Microbiana , Espectrometria de Massas em Tandem , beta-Lactamases/genética
3.
Clin Microbiol Rev ; 27(2): 241-63, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24696435

RESUMO

The OXA ß-lactamases were among the earliest ß-lactamases detected; however, these molecular class D ß-lactamases were originally relatively rare and always plasmid mediated. They had a substrate profile limited to the penicillins, but some became able to confer resistance to cephalosporins. From the 1980s onwards, isolates of Acinetobacter baumannii that were resistant to the carbapenems emerged, manifested by plasmid-encoded ß-lactamases (OXA-23, OXA-40, and OXA-58) categorized as OXA enzymes because of their sequence similarity to earlier OXA ß-lactamases. It was soon found that every A. baumannii strain possessed a chromosomally encoded OXA ß-lactamase (OXA-51-like), some of which could confer resistance to carbapenems when the genetic environment around the gene promoted its expression. Similarly, Acinetobacter species closely related to A. baumannii also possessed their own chromosomally encoded OXA ß-lactamases; some could be transferred to A. baumannii, and they formed the basis of transferable carbapenem resistance in this species. In some cases, the carbapenem-resistant OXA ß-lactamases (OXA-48) have migrated into the Enterobacteriaceae and are becoming a significant cause of carbapenem resistance. The emergence of OXA enzymes that can confer resistance to carbapenems, particularly in A. baumannii, has transformed these ß-lactamases from a minor hindrance into a major problem set to demote the clinical efficacy of the carbapenems.


Assuntos
Acinetobacter/enzimologia , Antibacterianos/farmacologia , Enterobacteriaceae/enzimologia , Resistência beta-Lactâmica , beta-Lactamases/metabolismo , Acinetobacter/genética , Acinetobacter/isolamento & purificação , Infecções por Acinetobacter/microbiologia , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Infecções por Enterobacteriaceae/microbiologia , Transferência Genética Horizontal , Humanos , beta-Lactamases/genética
4.
Antimicrob Resist Infect Control ; 12(1): 50, 2023 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-37226221

RESUMO

BACKGROUND: Infectious diseases are among the leading causes of death worldwide. This is concerning because of the increasing capacity of the pathogens to develop antibiotic resistance. Antibiotic overuse and misuse remain the main drivers of resistance development. In the USA and Europe, annual campaigns raise awareness of antibiotic misuse hazards and promote their judicial use. Similar efforts are lacking in Egypt. This study assessed the knowledge of the public in Alexandria, Egypt of antibiotic misuse risks and their habits towards antibiotic use, in addition to conducting a campaign to increase awareness of the safe use of antibiotics. METHODS: A questionnaire assessing knowledge, attitudes and behaviour towards antibiotics was used to collect responses from study participants at various sports clubs in Alexandria in 2019. An awareness campaign to correct misconceptions and a post awareness survey followed. RESULTS: Most of the participants were well-educated (85%), in their middle age (51%) and took antibiotics last year (80%). 22% would take an antibiotic for common cold. This dropped to 7% following the awareness. There was a 1.6 time increase in participants who would start an antibiotic on a healthcare professional's advice following the campaign. A 1.3 time increase in participants who would finish an antibiotic regimen was also observed. The campaign made all participants recognize that unwise antibiotic use is harmful to them or others; and 1.5 more participants would spread the word about antibiotic resistance. Despite learning of the risks of antibiotic use, there was no change in how often participants thought they should take antibiotics. CONCLUSIONS: Although awareness of antibiotic resistance is rising, some wrong perceptions hold fast. This highlights the need for patient and healthcare-tailored awareness sessions as part of a structured and national public health program directed to the Egyptian population.


Assuntos
Antibacterianos , Conhecimentos, Atitudes e Prática em Saúde , Pessoa de Meia-Idade , Humanos , Egito , Antibacterianos/efeitos adversos , Europa (Continente) , Instalações de Saúde
5.
Microb Genom ; 9(7)2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37439781

RESUMO

Acinetobacter baumannii is one the most worrisome nosocomial pathogens, which has long been considered almost mainly as a hospital-associated bacterium. There have been some studies about animal and environmental isolates over the last decade. However, little effort has been made to determine if this pathogen dwells in the grass. Here, we aim to determine the evolutionary relationships and antibiotic resistance of clones of A. baumannii sampled from grass to the major human international clones and animal clones. Two hundred and forty genomes were considered in total from four different sources for this study. Our core and accessory genomic epidemiology analyses showed that grass isolates cluster in seven groups well differentiated from one another and from the major human and animal isolates. Furthermore, we found new sequence types under both multilocus sequence typing schemes: two under the Pasteur scheme and seven for the Oxford scheme. The grass isolates contained fewer antibiotic-resistance genes and were not resistant to the antibiotics tested. Our results demonstrate that these novel clones appear to have limited antibiotic resistance potential. Given our findings, we propose that genomic epidemiology and surveillance of A. baumannii should go beyond the hospital settings and consider the environment in an explicit One Health approach.


Assuntos
Acinetobacter baumannii , beta-Lactamases , Animais , Humanos , beta-Lactamases/genética , Acinetobacter baumannii/genética , Antibacterianos/farmacologia , Tipagem de Sequências Multilocus , Células Clonais
6.
FEMS Microbes ; 4: xtad009, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37333444

RESUMO

Acinetobacter baumannii is a Gram-negative bacterium increasingly implicated in hospital-acquired infections and outbreaks. Effective prevention and control of such infections are commonly challenged by the frequent emergence of multidrug-resistant strains. Here we introduce Ab-web (https://www.acinetobacterbaumannii.no), the first online platform for sharing expertise on A. baumannii. Ab-web is a species-centric knowledge hub, initially with 10 articles organized into two main sections, 'Overview' and 'Topics', and three themes, 'epidemiology', 'antibiotic resistance', and 'virulence'. The 'workspace' section provides a spot for colleagues to collaborate, build, and manage joint projects. Ab-web is a community-driven initiative amenable to constructive feedback and new ideas.

7.
J Antimicrob Chemother ; 67(1): 59-63, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21980071

RESUMO

OBJECTIVES: This study examines the mechanism of carbapenem resistance in Acinetobacter baumannii isolate Ab244. METHODS: A multiplex PCR for the detection of the bla(OXA-23-like), bla(OXA-40-like), bla(OXA-51-like) and bla(OXA-58-like) families was performed. MICs of imipenem and meropenem were determined by the agar dilution method. The sequence surrounding the bla(OXA-132) gene was determined by amplification with primer pairs encompassing a part of fxsA and an acetyltransferase gene (GNAT). The sequence upstream of the bla(OXA-58) gene was determined by sequencing. SDS-PAGE and carO PCR were performed to check the integrity of the outer membrane proteins. RT-PCRs for the expression of the bla(OXA-132) gene and the bla(OXA-58) gene were performed. RESULTS: Isolate Ab244 harboured bla(OXA-132) belonging to the bla(OXA-51-like) gene cluster and a bla(OXA-58) gene. The 4239 bp region between fxsA and GNAT showed an insert of ISAba16 (where IS stands for insertion sequence) after the first 15 nucleotides of the bla(OXA-132) gene, with an 8 bp target site duplication at the 5' and 3' ends of ISAba16. The sequence oriented in the 5'→3' direction caused insertional inactivation of the bla(OXA-132) gene. The bla(OXA-58) gene was highly expressed by the promoters provided by an ISAba3-like structure found upstream of the gene. The isolate was resistant to meropenem and had intermediate resistance to imipenem, and was also positive for ISAba1. CONCLUSIONS: This is the first report showing ISAba16-mediated inactivation of the bla(OXA-132) gene in strain Ab244. The resistance to carbapenems in strain Ab244 is related to the acquisition of the bla(OXA-58) gene, here governed by an ISAba3-like element.


Assuntos
Acinetobacter baumannii/enzimologia , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Mutagênese Insercional , Resistência beta-Lactâmica , beta-Lactamases/genética , beta-Lactamases/metabolismo , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/genética , Proteínas da Membrana Bacteriana Externa/análise , DNA Bacteriano/química , DNA Bacteriano/genética , Eletroforese em Gel de Poliacrilamida , Perfilação da Expressão Gênica , Humanos , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Multiplex , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA
8.
J Magn Magn Mater ; 324(4): 501-507, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22184482

RESUMO

Magnetic elastomers have been widely pursued for sensing and actuation applications. Silicone-based magnetic elastomers have a number of advantages over other materials such as hydrogels, but aggregation of magnetic nanoparticles within silicones is difficult to prevent. Aggregation inherently limits the minimum size of fabricated structures and leads to non-uniform response from structure to structure. We have developed a novel material which is a complex of a silicone polymer (polydimethylsiloxane-co-aminopropylmethylsiloxane) adsorbed onto the surface of magnetite (γ-Fe(2)0(3)) nanoparticles 7-10 nm in diameter. The material is homogenous at very small length scales (< 100 nm) and can be crosslinked to form a flexible, magnetic material which is ideally suited for the fabrication of micro- to nanoscale magnetic actuators. The loading fraction of magnetic nanoparticles in the composite can be varied smoothly from 0 - 50% wt. without loss of homogeneity, providing a simple mechanism for tuning actuator response. We evaluate the material properties of the composite across a range of nanoparticle loading, and demonstrate a magnetic-field-induced increase in compressive modulus as high as 300%. Furthermore, we implement a strategy for predicting the optimal nanoparticle loading for magnetic actuation applications, and show that our predictions correlate well with experimental findings.

9.
Microb Genom ; 8(2)2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35104206

RESUMO

Carbapenem-resistant Acinetobacter baumannii are prevalent in low- and middle-income countries such as Egypt, but little is known about the molecular epidemiology and mechanisms of resistance in these settings. Here, we characterize carbapenem-resistant A. baumannii from Alexandria, Egypt, and place it in a regional context. Fifty-four carbapenem-resistant isolates from Alexandria Main University Hospital (AMUH), Alexandria, Egypt, collected between 2010 and 2015 were genome sequenced using Illumina technology. Genomes were de novo assembled and annotated. Genomes for 36 isolates from the Middle East region were downloaded from GenBank. The core-gene compliment was determined using Roary, and analyses of recombination were performed in Gubbins. Multilocus sequence typing (MLST) sequence type (ST) and antibiotic-resistance genes were identified. The majority of Egyptian isolates belonged to one of three major clades, corresponding to Pasteur MLST clonal complex (CCPAS) 1, CCPAS2 and STPAS158. Strains belonging to STPAS158 have been reported almost exclusively from North Africa, the Middle East and Pakistan, and may represent a region-specific lineage. All isolates carried an oxa23 gene, six carried blaNDM-1 and one carried blaNDM-2. The oxa23 gene was located on a variety of different mobile elements, with Tn2006 predominant in CCPAS2 strains, and Tn2008 predominant in other lineages. Of particular concern, in 8 of the 13 CCPAS1 strains, the oxa23 gene was located in a temperate bacteriophage phiOXA, previously identified only once before in a CCPAS1 clone from the USA military. The carbapenem-resistant A. baumannii population in AMUH is very diverse, and indicates an endemic circulating population, including a region-specific lineage. A major mechanism for oxa23 dissemination in CCPAS1 isolates appears to be a bacteriophage, presenting new concerns about the ability of these carbapenemases to spread throughout the bacterial population.


Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/genética , Proteínas de Bactérias/genética , Bacteriófagos/genética , Farmacorresistência Bacteriana Múltipla/genética , Infecções por Acinetobacter/epidemiologia , Infecções por Acinetobacter/microbiologia , África do Norte , Antibacterianos/farmacologia , Carbapenêmicos , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Genoma Bacteriano , Humanos , Testes de Sensibilidade Microbiana , Oriente Médio , Epidemiologia Molecular , Tipagem de Sequências Multilocus , Sequenciamento Completo do Genoma , beta-Lactamases/genética
10.
Microbiol Spectr ; 10(4): e0128922, 2022 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-35766493

RESUMO

Acinetobacter baumannii is a very important human pathogen. Nonetheless, we know very little about nonhuman isolates of A. baumannii. Here, we determine the genomic identity of 15 Scottish cattle and pig isolates, as well as their antibiotic and virulence genetic determinants, and compare them with 148 genomes from the main human clinical international clones. Our results demonstrate that cattle and pig isolates represent novel clones well separated from the major international clones. Furthermore, these new clones showed fewer antibiotic resistance genes and may have fewer virulence genes than human clinical isolates. IMPORTANCE Over the last decades, huge amounts of information have been obtained for clinical isolates of A. baumannii and the clones they belong to. In contrast, very little is known about the genomic identity and the genomic basis for virulence and resistance of animal isolates. To fulfil this gap, we conducted a genomic epidemiology study of 15 Scottish cattle and pig isolates in the context of almost 150 genomes belonging to the main international clones of A. baumannii. Our findings show that these animal isolates represent novel clones clearly different from the major international clones. Furthermore, these new clones are distinct in nature considering both antibiotic resistance and virulence when compared with their human clinical counterparts.


Assuntos
Infecções por Acinetobacter , Acinetobacter baumannii , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/epidemiologia , Infecções por Acinetobacter/veterinária , Acinetobacter baumannii/genética , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Bovinos , Células Clonais , Farmacorresistência Bacteriana Múltipla/genética , Humanos , Testes de Sensibilidade Microbiana , Suínos , Fatores de Virulência/genética , beta-Lactamases/genética
11.
Access Microbiol ; 4(10): acmi000412, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36415731

RESUMO

The OXA ß-lactamases are responsible for hydrolysing ß-lactam antibiotics and contribute to the multidrug-resistant phenotype of several major human pathogens. The OXAAb enzymes are intrinsic to Acinetobacter baumannii and can confer resistance to carbapenem antibiotics. Here we determined the structure of the most prevalent OXAAb enzyme, OXA-66. The structure of OXA-66 was solved at a resolution of 2.1 Å and found to be very similar to the structure of OXA-51, the only other OXAAb enzyme that has had its structure solved. Our data contained one molecule per asymmetric unit, and analysis of positions responsible for dimer formation in other OXA enzymes suggest that OXA-66 likely exists as a monomer.

13.
Adv Mater ; 33(25): e2008751, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33969551

RESUMO

Origami utilizes orchestrated transformation of soft 2D structures into complex 3D architectures, mimicking shapes and functions found in nature. In contrast to origami in nature, synthetic origami lacks the ability to monitor the environment and correspondingly adjust its behavior. Here, magnetic origami actuators with capabilities to sense their orientation and displacement as well as detect their own magnetization state and readiness for supervised folding are designed, fabricated, and demonstrated. These origami actuators integrate photothermal heating and magnetic actuation by using composite thin films (≈60 µm thick) of shape-memory polymers with embedded magnetic NdFeB microparticles. Mechanically compliant magnetic field sensors, known as magnetosensitive electronic skins, are laminated on the surface of the soft actuators. These ultrathin actuators accomplish sequential folding and recovery, with hinge locations programmed on the fly. Endowing mechanically active smart materials with cognition is an important step toward realizing intelligent, stimuli-responsive structures.

14.
Front Robot AI ; 8: 702566, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34368238

RESUMO

Small soft robotic systems are being explored for myriad applications in medicine. Specifically, magnetically actuated microrobots capable of remote manipulation hold significant potential for the targeted delivery of therapeutics and biologicals. Much of previous efforts on microrobotics have been dedicated to locomotion in aqueous environments and hard surfaces. However, our human bodies are made of dense biological tissues, requiring researchers to develop new microrobotics that can locomote atop tissue surfaces. Tumbling microrobots are a sub-category of these devices capable of walking on surfaces guided by rotating magnetic fields. Using microrobots to deliver payloads to specific regions of sensitive tissues is a primary goal of medical microrobots. Central nervous system (CNS) tissues are a prime candidate given their delicate structure and highly region-specific function. Here we demonstrate surface walking of soft alginate capsules capable of moving on top of a rat cortex and mouse spinal cord ex vivo, demonstrating multi-location small molecule delivery to up to six different locations on each type of tissue with high spatial specificity. The softness of alginate gel prevents injuries that may arise from friction with CNS tissues during millirobot locomotion. Development of this technology may be useful in clinical and preclinical applications such as drug delivery, neural stimulation, and diagnostic imaging.

15.
J Clin Microbiol ; 48(7): 2476-83, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20421437

RESUMO

This study used a diverse collection of epidemiologically unrelated Acinetobacter baumannii isolates to compare the robustness of a multilocus sequence typing (MLST) scheme, based on conserved regions of seven housekeeping genes, gltA, gdhB, recA, cpn60, rpoD, gyrB, and gpi, with that of sequence-based typing of bla(OXA-51-like) genes (SBT-bla(OXA-51-like) genes). The data obtained by analysis of MLST and SBT-bla(OXA-51-like) genes were compared to the data generated by pulsed-field gel electrophoresis (PFGE). The topologies of the phylogenetic trees generated for the gyrB and gpi genes showed evidence of recombination and were inconsistent with those of the trees generated for the other five genes. MLST identified 24 sequence types (STs), of which 19 were novel, and 5 novel alleles. Clonality was demonstrated by eBURST analysis and standardized index of association values of >1 (P < 0.001). MLST data revealed that all isolates harboring the major bla(OXA-51-like) alleles OXA-66, OXA-69, and OXA-71 fell within the three major European clonal lineages. However, the MLST data were not always in concordance with the PFGE data, and some isolates containing the same bla(OXA-51-like) allele demonstrated <50% relatedness by PFGE. It was concluded that the gyrB and gpi genes are not good candidates for use in MLST analysis and that a SBT-bla(OXA-51-like) gene scheme produced results comparable to those produced by MLST for the identification of the major epidemic lineages, with the advantage of having a significantly reduced sequencing cost and time. It is proposed that studies of A. baumannii epidemiology could involve initial screening of bla(OXA-51-like) alleles to identify isolates belonging to major epidemic lineages, followed by MLST analysis to categorize isolates from common lineages, with PFGE being reserved for fine-scale typing.


Assuntos
Acinetobacter baumannii/genética , Proteínas de Bactérias/genética , Eletroforese em Gel de Campo Pulsado/métodos , Análise de Sequência de DNA/métodos , beta-Lactamases/genética , Infecções por Acinetobacter/epidemiologia , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/classificação , Análise por Conglomerados , Humanos , Filogenia
16.
Proc Biol Sci ; 277(1696): 2991-9, 2010 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-20462905

RESUMO

Quorum sensing (QS) in bacteria is thought to enable populations of cells to coordinately and cooperatively regulate gene expression for traits that confer group benefits. While this view has strong empirical and theoretical support, it is increasingly appreciated that QS under natural conditions may be incapable of monitoring bacterial numbers and, furthermore, that QS is evolutionarily unstable owing to conflicts of interest among competing cells. An alternative hypothesis, termed diffusion sensing (DS), proposes that autoinducer secretion monitors the diffusive properties of the local environment, with benefits that are directly realized by individual cells rather than populations. Here, we test central predictions of this hypothesis using the competence signalling system of Streptococcus pneumoniae as our model, which regulates the induction of natural transformation by the secretion and detection of a small diffusible peptide, CSP (competence-stimulating peptide). By experimentally manipulating the diffusive properties of the growth medium, we found that there is no fixed quorum for competence induction. Instead, induction cell density scales with diffusivity. In agreement with QS and DS expectations, we show that the benefit of signal exploitation by mutant cells that can use but not secrete CSP is strongly frequency-dependent. However, we also find that the magnitude of this benefit declines significantly as diffusion is reduced, a result more consistent with the predictions of DS. Together, these data provide strong support for the DS hypothesis for autoinducer response systems. More specifically, our results imply that autonomous rather than group benefits should be sought in order to more completely understand the role and evolution of CSP signalling in pneumococci.


Assuntos
Proteínas de Bactérias/metabolismo , Percepção de Quorum/fisiologia , Streptococcus pneumoniae/fisiologia , Evolução Biológica , Difusão , Modelos Biológicos , Streptococcus pneumoniae/citologia , Streptococcus pneumoniae/metabolismo
17.
Microb Genom ; 6(6)2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32496178

RESUMO

Acinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host-cell recognition, biofilm formation, regulation of OM stability, permeability and antibiotic resistance. OmpA members are two-domain proteins with an N-terminal eight-stranded ß-barrel domain with four external loops (ELs) interacting with the environment, and a C-terminal periplasmic domain binding non-covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic and multilocus sequence analyses from 975 strains/isolates of the Acinetobacter calcoaceticus/Acinetobacter baumannii complex (ACB), 946 from A. baumannii, to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) in A. baumannii, encompassing 52 different alleles coding for 23 different proteins. Polymorphisms were concentrated in five regions corresponding to the four ELs and the C-terminal end, and provided evidence for intra-genic recombination. ompA variants were not randomly distributed across the A. baumannii phylogeny, with the most frequent V1(lct)a1 allele found in most clonal complex 2 (CC2) strains and the second most frequent V2(lct)a1 allele in the majority of CC1 strains. Evidence was found for assortative exchanges of ompA alleles not only between separate A. baumannii lineages, but also different ACB species. The overall results have implications for A. baumannii evolution, epidemiology, virulence and vaccine design.


Assuntos
Acinetobacter baumannii/classificação , Proteínas da Membrana Bacteriana Externa/genética , Variação Genética , Acinetobacter baumannii/genética , Acinetobacter baumannii/patogenicidade , Bases de Dados Genéticas , Evolução Molecular , Tipagem de Sequências Multilocus , Filogenia , Sequenciamento Completo do Genoma
18.
mSphere ; 5(1)2020 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-31915222

RESUMO

Over the last few decades, carbapenemase-producing Acinetobacter baumannii has become a major cause of nosocomial infections all over the world. However, the genome identity of lineages of this species in Latin America has not been studied as much as in developed countries. Here, through a population genomics approach considering the whole genomes of 148 isolates (almost 40 from Mexico and Honduras), we describe the recent emergence of the lineage sequence type 758 (ST758), which belongs to the international clone V and has spread out to Canada, Mexico, Honduras, and Colombia. Notably, this lineage was found to coexist with other A. baumannii lineages in hospitals in Mexico and Honduras. Isolates from this lineage show considerable variation in antibiotic resistance profiles, but most of them are resistant to carbapenems. Moreover, we found a variety of acquired oxacillinase (OXA) families within this lineage and tracked the very recent inception, and subsequent horizontal transmission, of the OXA-239 carbapenemase. This work highlights the urgent need to investigate recently emerged lineages of this species in Latin America and elsewhere, as these might harbor novel antibiotic resistance genes.IMPORTANCEA. baumannii is a major cause of nosocomial infections all over the world. Although many isolates from developed countries have been studied in terms of their genome sequence, isolates from Latin America have been much less studied. In this study, using a population genomics approach considering the whole genomes of 148 isolates, we describe the recent emergence of the lineage ST758 endemic to Latin America and the inception of the OXA-239 carbapenemase. Our study highlights the urgent need to investigate recently emerged lineages of this species in Latin America and elsewhere, as these might harbor novel antibiotic resistance genes.


Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/enzimologia , Genoma Bacteriano , beta-Lactamases/genética , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/classificação , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Infecção Hospitalar/microbiologia , Farmacorresistência Bacteriana Múltipla/genética , Genômica , Honduras , Humanos , México , Testes de Sensibilidade Microbiana
19.
Sci Adv ; 5(8): eaaw2897, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31414046

RESUMO

New materials are advancing the field of soft robotics. Composite films of magnetic iron microparticles dispersed in a shape memory polymer matrix are demonstrated for reconfigurable, remotely actuated soft robots. The composite films simultaneously respond to magnetic fields and light. Temporary shapes obtained through combined magnetic actuation and photothermal heating can be locked by switching off the light and magnetic field. Subsequent illumination in the absence of the magnetic field drives recovery of the permanent shape. In cantilevers and flowers, multiple cycles of locking and unlocking are demonstrated. Scrolls show that the permanent shape of the film can be programmed, and they can be frozen in intermediate configurations. Bistable snappers can be magnetically and optically actuated, as well as biased, by controlling the permanent shape. Grabbers can pick up and release objects repeatedly. Simulations of combined photothermal heating and magnetic actuation are useful for guiding the design of new devices.

20.
Micromachines (Basel) ; 10(4)2019 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-30935105

RESUMO

Soft, untethered microrobots composed of biocompatible materials for completing micromanipulation and drug delivery tasks in lab-on-a-chip and medical scenarios are currently being developed. Alginate holds significant potential in medical microrobotics due to its biocompatibility, biodegradability, and drug encapsulation capabilities. Here, we describe the synthesis of MANiACs-Magnetically Aligned Nanorods in Alginate Capsules-for use as untethered microrobotic surface tumblers, demonstrating magnetically guided lateral tumbling via rotating magnetic fields. MANiAC translation is demonstrated on tissue surfaces as well as inclined slopes. These alginate microrobots are capable of manipulating objects over millimeter-scale distances. Finally, we demonstrate payload release capabilities of MANiACs during translational tumbling motion.

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