Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Lab Physicians ; 15(1): 117-125, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37064978

RESUMO

Objectives This study aimed to evaluate the performance of routinely used phenotypic tests to detect ß-lactamase production in isolates coproducing multiple ß-lactamase types. Methods Commonly used phenotypic tests for the detection of extended spectrum ß-lactamases (ESBL), AmpC ß-lactamase, and carbapenemases were compared with detection and sequencing of ß-lactamase genes (as the reference test) in 176 uropathogenic Enterobacteriaceae coproducing multiple ß-lactamases from two hospitals in the Western Province of Sri Lanka. Results Majority of the isolates (147/176, 83.5%) carried ß-lactamase genes with (90/147, 61%) harboring multiple genes. The Clinical and Laboratory Standards Institute screening method using cefotaxime (sensitivity [Se], 97; specificity [Sp], 93; accuracy [Ac], 94) and ceftriaxone (Se, 97; Sp, 91; Ac, 93) was the most effective to detect ESBLs. The modified double disc synergy test (Se, 98; Sp, 98; Ac, 97) and combined disc test (Se, 94; Sp, 98; Ac, 96) showed good specificity for confirmation of ESBLs. Cefoxitin resistance (Se, 97; Sp, 73; Ac, 85) and the AmpC disc test (Se, 96; Sp, 82; Ac, 86) were sensitive to detect AmpC ß-lactamase producers coproducing other ß-lactamases but showed low specificity, probably due to coproduction of carbapenemases. Meropenem was useful to screen for New Delhi metallo ß-lactamases and OXA-48-like carbapenemases (Se, 97; Sp, 96; Ac, 96). The modified carbapenem inactivation method showed excellent performance (Se, 97; Sp, 98; Ac, 97) in identifying production of both types of carbapenemases and was able to distinguish this from carbapenem resistance due to potential mutations in the porin gene. Conclusion Microbiology laboratories that are still depend on phenotypic tests should utilize tests that are compatible with the types of ß-lactamase prevalent in the region and those that are least affected by coexisting resistance mechanisms.

2.
Microb Drug Resist ; 28(8): 882-892, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35972764

RESUMO

The study describes the first isolation of multidrug-resistant (MDR) Klebsiella pneumoniae ST16, Escherichia coli ST131 (Esc), and Enterobacter hormaechei subsp. steigerwaltii ST93 (Enterobacter cloacae complex [ECC]) in Sri Lanka. Eight MDR strains of uropathogenic Enterobacterales isolated from hospital acquired urinary tract infections (UTIs) were analyzed using genomic sequencing and comparative genomics. Isolates carried multiple carbapenemase, AmpC, and ESBL (extended-spectrum ß-lactamase) genes. ECC manifested both blaNDM-4 and blaOXA-181. The K. pneumoniae strains harbored fimbrial genes that facilitate pathogenesis of UTI. Several extraintestinal pathogenic E. coli associated virulence genes were identified in Esc. The efflux pump gene, acrA, and the T6SS gene cluster were detected in ECC. Many antimicrobial resistance (AMR) and virulence genes were identified associated with mobile genetic elements. ISEcp1 flanked upstream of blaCTX-M-15. The carbapenemase genes were carried on ColKP3 plasmids and were associated with ISEcp1. In Esc, the AMR gene blaTEM-1B and virulence gene traT were found on an IncF plasmid replicon. In K. pneumoniae the AMR genes sul1 and tetB present on IncR plasmid replicons and were associated with the insertion sequence IS6100. In Kp5, blaLAP-2 and qnrS1 coexisted and were flanked by ISEcl. AMR gene clusters, conferring resistance to multiple antimicrobial classes, flanked by mobile elements were identified in seven isolates.


Assuntos
Farmacorresistência Bacteriana Múltipla , Enterobacter , Escherichia coli , Klebsiella pneumoniae , Infecções Urinárias , Antibacterianos/farmacologia , Infecção Hospitalar/microbiologia , Farmacorresistência Bacteriana Múltipla/genética , Enterobacter/efeitos dos fármacos , Enterobacter/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Humanos , Sequências Repetitivas Dispersas , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Testes de Sensibilidade Microbiana , Sri Lanka/epidemiologia , Infecções Urinárias/tratamento farmacológico , Infecções Urinárias/microbiologia , Virulência/genética , beta-Lactamases/genética
3.
PLoS One ; 13(10): e0204296, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30335750

RESUMO

Nanoparticles often only exploit the upregulation of a receptor on cancer cells to enhance intratumoral deposition of therapeutic and imaging agents. However, a single targeting moiety assumes that a tumor is homogenous and static. Tumoral microenvironments are both heterogenous and dynamic, often displaying variable spatial and temporal expression of targetable receptors throughout disease progression. Here, we evaluated the in vivo performance of an iron oxide nanoparticle in terms of targeting and imaging of orthotropic mouse models of aggressive breast tumors. The nanoparticle, a multi-component nanochain, was comprised of 3-5 iron oxide nanoparticles chemically linked in a linear chain. The nanoparticle's surface was decorated with two types of ligands each targeting two different upregulated biomarkers on the tumor endothelium, P-selectin and fibronectin. The nanochain exhibited improved tumor deposition not only through vascular targeting but also through its elongated structure. A single-ligand nanochain exhibited a ~2.5-fold higher intratumoral deposition than a spherical nanoparticle variant. Furthermore, the dual-ligand nanochain exhibited higher consistency in generating detectable MR signals compared to a single-ligand nanochain. Using a 7T MRI, the dual-ligand nanochains exhibited highly detectable MR signal within 3h after injection in two different animal models of breast cancer.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Fibronectinas/metabolismo , Nanopartículas/química , Selectina-P/metabolismo , Peptídeos/administração & dosagem , Animais , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Feminino , Compostos Ferrosos/química , Humanos , Imageamento por Ressonância Magnética , Camundongos , Imagem Molecular , Transplante de Neoplasias , Peptídeos/química , Sensibilidade e Especificidade
4.
Case Rep Infect Dis ; 2018: 4610246, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29666727

RESUMO

Emergence of cephalosporin-resistant strains of Salmonella enterica serovar Typhi is a cause of concern in the management of enteric fever. Cephalosporin resistance in Salmonella species is mainly due to the production of extended-spectrum ß-lactamases (ESBLs). The majority of ESBLs in Salmonella enterica serovar Typhi are derivatives of the TEM, SHV, and CTX-M ß-lactamase families. Of these, CTX-M appears to be predominant. This paper discusses the detection and molecular characterization of an ESBL-producing Salmonella enterica serovar Typhi strain isolated from a patient who was admitted to a private hospital in Sri Lanka. The three main types of ß-lactamases such as TEM, SHV, and CTX-M were identified in this isolate. This case report from Sri Lanka contributes to the knowledge of the increasingly reported cases of typhoid fever due to Salmonella enterica serovar Typhi resistant to ß-lactamase by ESBL production.

5.
Analyst ; 141(6): 2016-22, 2016 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-26890149

RESUMO

Biocompatible nanoparticles of gadolinium-incorporated Prussian blue with the empirical formula K(0.94)Gd(0.02)Fe[Fe(CN)6] exhibit extremely high stability against the release of Gd(3+) and CN(-) ions under the acidic conditions similar to stomach juice. The high r1 relaxivity, low cytotoxicity and the ability of such nanoparticles to penetrate the cell membrane suggest that this coordination-polymer structural platform offers a unique opportunity for developing the next generation of T1-weighted oral cellular MRI probes for the early detection of tumors in the gastrointestinal tract.


Assuntos
Meios de Contraste/química , Ferrocianetos/química , Gadolínio/química , Trato Gastrointestinal/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Nanopartículas/química , Polietilenoglicóis/química , Animais , Transporte Biológico , Meios de Contraste/metabolismo , Meios de Contraste/toxicidade , Estabilidade de Medicamentos , Células HT29 , Humanos , Coelhos
6.
Langmuir ; 30(40): 12018-26, 2014 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-25238130

RESUMO

A simple one-step method for preparing biocompatible nanoparticles of gadolinium ferrocyanide coordination polymer KGd(H2O)2[Fe(CN)6]·H2O is reported. The crystal structure of this coordination polymer is determined by X-ray powder diffraction using the bulk materials. The stability, cytotoxicity, cellular uptake, and MR phantom and cellular imaging studies suggest that this coordination-polymer structural platform offers a unique opportunity for developing the next generation of T1-weighted contrast agents with high relaxivity as cellular MR probes for biological receptors or markers. Such high-relaxivity MR probes may hold potential in the study of molecular events and may be used for in vivo MR imaging in biomedical research and clinical applications.


Assuntos
Materiais Biocompatíveis/química , Meios de Contraste/química , Complexos de Coordenação/química , Ferrocianetos/química , Gadolínio/química , Animais , Cristalografia por Raios X , Humanos , Imageamento por Ressonância Magnética , Imagem Molecular/instrumentação , Imagem Molecular/métodos , Nanopartículas/química , Nanopartículas/ultraestrutura , Imagens de Fantasmas , Água/química
7.
J Mater Chem B ; 2(3): 257-261, 2014 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-25821583

RESUMO

Biocompatible ZnMoS4 NPs can selectively remove intracellular copper ions via ion-exchange rather than chelation. This strategy represents a paradigm shift in designing new-generation intracellular metal detoxifying drugs.

8.
Langmuir ; 29(12): 4032-8, 2013 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-23461604

RESUMO

A series of cysteine-stabilized phenolic resin-based polymer and carbon spheres were prepared by the modified Stöber method. Cysteine plays a very important role in the proposed one-pot synthesis of the aforementioned spheres; namely, it acts as a particle stabilizer and a source of heteroatoms (nitrogen and sulfur) that can be introduced into these spheres. The diameter of these spheres can be tuned in the range of 70-610 nm by adjusting the cysteine amount and reaction temperature. Since polymer spheres obtained in the presence of cysteine contain sulfur and nitrogen heteroatoms, they were tested for adsorption of copper ions. It is shown that adsorption isotherms recorded for copper ions can be well fitted by Langmuir equation, giving unprecedented adsorption capacities up to ~65 mg/g.


Assuntos
Carbono/química , Sulfato de Cobre/isolamento & purificação , Cisteína/química , Formaldeído/química , Fenóis/química , Polímeros/química , Adsorção , Nitrogênio/química , Tamanho da Partícula , Enxofre/química , Temperatura , Purificação da Água/métodos
9.
Chem Mater ; 25(23): 4703-4709, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-25698847

RESUMO

A layer-by-layer self-assembly method leads to the formation of Au@ZnMoS4 core-shell nanoparticles (NPs). The PEGylated Au@ZnMoS4 NPs are highly water-dispersible, exhibit no cytotoxicity and can penetrate the cell membrane to selectively remove copper(I) ions from HepG2 cells in the presence of other endogenous and biologically essential metal ions including Mg(II), Ca(II), Mn(II) and Fe(II), demonstrating their potential as a novel intracellular copper detoxifying agent.

10.
Inorg Chem ; 50(17): 7910-2, 2011 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-21797245

RESUMO

An aqueous synthetic procedure for preparing nanoparticles of the novel potassium bismuth ferrocyanide coordination polymer KBi(H(2)O)(2)[Fe(CN)(6)]·H(2)O is reported. The crystal structure of this coordination polymer is determined through X-ray powder diffraction using the bulk materials. The stability, cytotoxicity, and potential use of such nanoparticles coated with PVP as a CT contrast agent are investigated.


Assuntos
Meios de Contraste/síntese química , Nanopartículas/química , Tomografia Computadorizada por Raios X , Bismuto/química , Bismuto/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Meios de Contraste/química , Relação Dose-Resposta a Droga , Ferrocianetos/química , Ferrocianetos/farmacologia , Células HeLa , Humanos , Modelos Moleculares , Tamanho da Partícula , Polivinil/química , Potássio/química , Difração de Pó , Pirrolidinas/química , Propriedades de Superfície
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...