Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.042
Filtrar
1.
Wiad Lek ; 73(8): 1615-1619, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33055321

RESUMO

OBJECTIVE: The aim: To perform microbiological investigation and analytic mathematic prediction of clinical isolates of S. aureus to aminoglycosides in patients with severe burns. PATIENTS AND METHODS: Materials and methods: We analyzed resistance of 199 S. aureus strains to aminoglycosides (gentamicin, tobramycin and amikacin) and doxycycline from 435 patients treated in the regional hospital due to burns for the period from 2011-2017. RESULTS: Results: We created predictive curves for the prediction of susceptibility of S. aureus strains to aminoglycosides and doxycycline based on the changes in S. aureus resistance during the years of observation and expressed in mathematic equations. Susceptibility of S. aureus to gentamicin was 42.86 % at the end of observation and will decline in future. Despite tobramycin was efficient against 72.86 % of strains in 2017, mathematic modeling indicates rapid decline in its efficacy in future. Efficacy of amikacin was dropping during the last years, but according to the equation it efficacy will increase over 60 % in 2018. S. aureus susceptibility to doxycycline was 65.38 % in 2017 and mathematic modeling indicates its gradual decline in the nearest future. CONCLUSION: Conclusions: Predicitive values of S. aureus susceptibility indicates not sufficient efficacy of these drugs in patients with infectious complications of burns. Tendency of the slight decline of S. aureus susceptibility to doxycycline still indicates sufficient levels of its efficacy in the nearest future. This justify its use as a second-line therapy with the causative agent in patients with burns.


Assuntos
Aminoglicosídeos , Doxiciclina , Aminoglicosídeos/farmacologia , Doxiciclina/farmacologia , Doxiciclina/uso terapêutico , Resistência Microbiana a Medicamentos , Humanos , Prognóstico , Staphylococcus , Staphylococcus aureus
2.
Proc Natl Acad Sci U S A ; 117(38): 23565-23570, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32900959

RESUMO

l-cysteine is the source of all bacterial sulfurous biomolecules. However, the cytoplasmic level of l-cysteine must be tightly regulated due to its propensity to reduce iron and drive damaging Fenton chemistry. It has been proposed that in Escherichia coli the component of cytochrome bd-I terminal oxidase, the CydDC complex, shuttles excessive l-cysteine from the cytoplasm to the periplasm, thereby maintaining redox homeostasis. Here, we provide evidence for an alternative function of CydDC by demonstrating that the cydD phenotype, unlike that of the bona fide l-cysteine exporter eamA, parallels that of the l-cystine importer tcyP. Chromosomal induction of eamA, but not of cydDC, from a strong pLtetO-1 promoter (Ptet) leads to the increased level of extracellular l-cysteine, whereas induction of cydDC or tcyP causes the accumulation of cytoplasmic l-cysteine. Congruently, inactivation of cydD renders cells resistant to hydrogen peroxide and to aminoglycoside antibiotics. In contrast, induction of cydDC sensitizes cells to oxidative stress and aminoglycosides, which can be suppressed by eamA overexpression. Furthermore, inactivation of the ferric uptake regulator (fur) in Ptet-cydDC or Ptet-tcyP cells results in dramatic loss of survival, whereas catalase (katG) overexpression suppresses the hypersensitivity of both strains to H2O2 These results establish CydDC as a reducer of cytoplasmic cystine, as opposed to an l-cysteine exporter, and further elucidate a link between oxidative stress, antibiotic resistance, and sulfur metabolism.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Cisteína/metabolismo , Grupo dos Citocromos b/metabolismo , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Proteínas de Escherichia coli/metabolismo , NADH NADPH Oxirredutases/metabolismo , Estresse Oxidativo/fisiologia , Oxirredutases/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Aminoglicosídeos/metabolismo , Aminoglicosídeos/farmacologia , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Grupo dos Citocromos b/genética , Citoplasma/enzimologia , Citoplasma/metabolismo , Complexo de Proteínas da Cadeia de Transporte de Elétrons/genética , Proteínas de Escherichia coli/genética , Peróxido de Hidrogênio/metabolismo , NADH NADPH Oxirredutases/genética , Estresse Oxidativo/genética , Oxirredutases/genética , Periplasma/metabolismo
3.
PLoS One ; 15(9): e0237948, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32877437

RESUMO

The lack of new antibiotics necessitates the improvement of existing ones, many of which are limited by toxic side effects. Aminoglycosides, antibiotics with excellent activity and low bacterial resistance, are hampered by dose-dependent toxic effects in patients (nephrotoxicity, ototoxicity). High antibiotic concentrations are often required to treat dormant, non-dividing bacteria, though previous studies show that aminoglycosides can be activated against such bacteria by specific metabolites. Here, we employed this mechanism to greatly boost the activity of low concentrations of aminoglycosides against prevalent Gram-negative pathogens (Escherichia coli, Salmonella enterica, and Klebsiella pneumoniae), suggesting that less toxic drug concentrations might be used effectively in patients. We go on to show that this effect improved treatment of biofilms, did not increase aminoglycoside resistance, and was due to the generation of proton-motive force (PMF). By single-cell microscopy, we demonstrate that stationary-phase cells, while non-dividing, actively maintain a growth-arrested state that is not reversed by metabolite addition. Surprisingly, within starved populations, we observed rare cells (3%) that divided without added nutrients. Additionally, we discovered that mannitol could directly protect human kidney cells from aminoglycoside cytotoxicity, independent of the metabolite's effect on bacteria. This work forwards a mechanism-based strategy to improve existing antibiotics by mitigating their toxic side effects.


Assuntos
Aminoglicosídeos/química , Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Bactérias/crescimento & desenvolvimento , Infecções Bacterianas/tratamento farmacológico , Biofilmes/crescimento & desenvolvimento , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/prevenção & controle , Antibacterianos/química , Bactérias/efeitos dos fármacos , Infecções Bacterianas/microbiologia , Infecções Bacterianas/patologia , Biofilmes/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana
4.
Int J Food Microbiol ; 333: 108831, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-32854018

RESUMO

Salmonella enterica subsp. enterica serovars are considered major causes of food poisoning and we performed this study because Salmonella is a burden in Lebanon. The present study investigated the ability of genomic information to predict serovar using a collection of Salmonella isolates from infected humans (n = 24) and contaminated food (n = 63) in Lebanon. Further, the phylogenomic relationships of the serovar the predominated in Lebanon (i.e., S. Enteritidis; n = 25) were investigated in comparison with isolates from other countries (n = 130) based on coregenome single nucleotide polymorphisms (SNPs). Genetic elements, specifically Salmonella pathogenicity islands (SPIs), plasmid replicons, and antibiotic-resistance genes were screened in S. Enteritidis genomes (n = 155). Our results revealed that the Salmonella serovars identification by seroagglutination from the samples isolated in Lebanon (n = 87) was highly correlated with the genomic-based prediction of serovars (80.4-85.0% with SeqSero1 and 93.1-94.2% with SeqSero2). The Salmonella serovars isolated from human and food samples in Lebanon were mainly Enteritidis (28.7%) and Infantis (26%). To a rare extent, other serovars included Amager, Anatum, Bredeney, Chincol, Heidelberg, Hofit, Kentucky, Montevideo, Muenster, Newport, Schwarzengrund, Senftenberg and Typhimurium. In comparison with other countries, S. Enteritidis samples isolated in Lebanon (56 ± 27 intra-group pairwise SNP differences) presented a strong phylogenomic relativeness at the coregenome level with samples, as for example with samples isolated from Syria (65 ± 31 inter-group pairwise SNP differences). Most of the studied S. Enteritidis genomes encoded 10 SPIs involved in survival in immune cells (i.e. SPIs 1, 2, 3, 4, 5, 12, 13, 14, 16 and 17). The plasmid replicons IncFIB (S)_1 and IncFII (S)_1 encoding elements involved in virulence were identified in the majority of the S. Enteritidis genomes (94% and 96%, respectively), the majority exhibiting aminoglycosides (gene aac(6')-Iaa_1). The IncI_1_Alpha replicon responsible for ampicillin-resistance was only detected in 2 of 25 S. Enteritidis Lebanese strains. Genomic-based risk assessment of Salmonella serovars in Lebanon showed that food imported from Syria might be an origin of the S. Enteritidis human cases in Lebanon. The detection of several SPIs involved in the survival, plasmid replicons involved in virulence, and aminoglycoside-resistance genes, emphasizes that S. Enteritidis is of paramount importance for public health in Lebanon and other countries.


Assuntos
Ilhas Genômicas/genética , Salmonella enteritidis/classificação , Salmonella enteritidis/genética , Salmonella/classificação , Salmonella/genética , Aminoglicosídeos/farmacologia , Animais , Antibacterianos/farmacologia , Genômica , Humanos , Líbano , Filogenia , Plasmídeos/genética , Polimorfismo de Nucleotídeo Único/genética , Saúde Pública , Salmonella/isolamento & purificação , Salmonella enteritidis/isolamento & purificação , Sorogrupo , Virulência , Fatores de Virulência/genética
5.
PLoS One ; 15(7): e0235929, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32645104

RESUMO

Combinations of three or more drugs are routinely used in various medical fields such as clinical oncology and infectious diseases to prevent resistance or to achieve synergistic therapeutic benefits. The very large number of possible high-order drug combinations presents a formidable challenge for discovering synergistic drug combinations. Here, we establish a guided screen to discover synergistic three-drug combinations. Using traditional checkerboard and recently developed diagonal methods, we experimentally measured all pairwise interactions among eight compounds in Erwinia amylovora, the causative agent of fire blight. Showing that synergy measurements of these two methods agree, we predicted synergy/antagonism scores for all possible three-drug combinations by averaging the synergy scores of pairwise interactions. We validated these predictions by experimentally measuring 35 three-drug interactions. Therefore, our guided screen for discovering three-drug synergies is (i) experimental screen of all pairwise interactions using diagonal method, (ii) averaging pairwise scores among components to predict three-drug interaction scores, (iii) experimental testing of top predictions. In our study, this strategy resulted in a five-fold reduction in screen size to find the most synergistic three-drug combinations.


Assuntos
Antibacterianos/química , Sinergismo Farmacológico , Aminoglicosídeos/química , Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Sulfato de Cobre/química , Sulfato de Cobre/farmacologia , Interações Medicamentosas , Erwinia amylovora/efeitos dos fármacos , Erwinia amylovora/crescimento & desenvolvimento , Gentamicinas/química , Testes de Sensibilidade Microbiana
6.
BMC Infect Dis ; 20(1): 544, 2020 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-32711470

RESUMO

BACKGROUND: This study aimed to identify ten different 16S rRNA methyltransferase genes (rmtA, rmtB, rmtC, rmtD, armA, rmtF, npmA, rmtH, rmtE and rmtG) and their coexisting ESBL and carbapenemase with the emergence of three E.coli clones within a single study centre. METHODS: A total of 329 non-duplicate E.coli isolates were studied to detect the presence of 16S rRNA methyltransferases along with ß-lactamases (TEM, SHV, OXA, VEB, GES, PER,CTX-M types, NDM, OXA-48,VIM, IMP and KPC) using PCR assay. Horizontal transferability were validated by transformation and conjugation analysis. Plasmid incompatibility typing and MLST analysis was also performed. RESULTS: A total of 117 isolates were found to be resistant to at least one of the aminoglycoside antibiotics. It was observed that 77 (65.8%) were positive for 16S rRNA methyltransferases. Among them thirty nine isolates were found to harbour only blaCTX-M-15, whereas combination of genes were observed in three isolates (blaVEB+ blaCTX-M-15 in 2 isolates and blaPER + blaCTX-M-15 in 1 isolate). blaNDM and blaOXA-48 like genes were found in 23 and 9 isolates, respectively. All the resistance genes were conjugatively transferable, and incompatibility typing showed multiple 16S rRNA methyltransferase genes were originated from a single Inc. I1 group. MLST analysis detected 3 clones of E.coliST4410, ST1341 and ST3906. CONCLUSION: The present study identified emergence of three clones of E.coli, resistant to aminoglycoside -cephalosporin- carbapenem. This warrants immediate measures to trace their transmission dynamics in order to slow down their spread in clinical setting.


Assuntos
Proteínas de Escherichia coli/genética , Escherichia coli/genética , Metiltransferases/genética , beta-Lactamases/genética , Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Técnicas de Tipagem Bacteriana , Carbapenêmicos/farmacologia , Cefalosporinas/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Escherichia coli/classificação , Escherichia coli/efeitos dos fármacos , Genes Bacterianos/genética , Humanos , Índia , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus
7.
J Med Chem ; 63(11): 6090-6095, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32378891

RESUMO

A novel lipopeptide antibiotic, stalobacin I (1), was discovered from a culture broth of an unidentified Gram-negative bacterium. Stalobacin I (1) had a unique chemical architecture composed of an upper and a lower half peptide sequence, which were linked via a hemiaminal methylene moiety. The sequence of 1 contained an unusual amino acid, carnosadine, 3,4-dihydroxyariginine, 3-hydroxyisoleucine, and 3-hydroxyaspartic acid, and a novel cyclopropyl fatty acid. The antibacterial activity of 1 against a broad range of drug-resistant Gram-positive bacteria was much stronger than those of "last resort" antibiotics such as vancomycin, linezolid, and telavancin (MIC 0.004-0.016 µg/mL). Furthermore, compound 1 induced a characteristic morphological change in Gram-positive and Gram-negative strains by inflating the bacterial cell body. The absolute configuration of a cyclopropyl amino acid, carnosadine, was determined by the synthetic study of its stereoisomers, which was an essential component for the strong activity of 1.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Lipopeptídeos/química , Aminoglicosídeos/farmacologia , Antibacterianos/química , Avaliação Pré-Clínica de Medicamentos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Lipoglicopeptídeos/farmacologia , Lipopeptídeos/farmacologia , Testes de Sensibilidade Microbiana
8.
Vet Microbiol ; 243: 108641, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32273020

RESUMO

Riemerella anatipestifer is a Gram-negative bacterium, which is an important pathogen infecting ducks and resistant to various antibiotics. The efflux pump is an important resistance mechanism of Gram-negative bacteria, but little research has been done in R. anatipestifer. In this study, the drug resistance mediated by RIA_1614 gene of R. anatipestifer RA-GD strain was studied, because the gene was presumed to be an efflux pump component of ABC. Firstly, the deletion strain RA-GD△RIA_1614 and complemented strain RA-GD△RIA_1614 pCPRA::RIA_1614 were constructed. Then, MICs of various antimicrobial agents to parent and deletion strains and the tolerance of the strains to organic solvents were detected to screen the substrates for RIA_1614 gene. Moreover, the transcription levels of RIA_1614 gene in the parent and the complemented strains exposed to the substrates were detected by quantitative real-time RT-PCR. Furthermore, the efflux abilities of parent, deletion and complemented strains to substrates were determined by antibiotic accumulation test. In addition, in vitro competition ability and virulence of the strains were also detected. The results showed that the deletion strain was more sensitive to aminoglycosides and organic solvents than parental strain RA-GD. When RA-GD and complemented strain were exposed to sub-repression levels of aminoglycosides and organic solvents, the transcription levels of RIA_1614 gene were significantly up-regulated. Sodium o-vanadate inhibitor assay confirmed that RIA_1614 protein contributed to amikacin and streptomycin resistance and organic solvent tolerance. Streptomycin accumulation test showed that the RIA_1614 protein was able to export streptomycin, and the addition of ATPase inhibitor sodium o-vanadate increased the accumulation of streptomycin, indicating that RIA_1614 protein was an ATP-dependent efflux transporter. Growth and competition experiments revealed that RIA_1614 protein had no significant effect on growth of RA-GD, but decreased in vitro competition ability of the strain. Furthermore, pathogenicity tests showed that RIA_1614 protein involved in the virulence of the strain. Based on the results and amino acid sequence analysis, it was determined that RIA_1614 protein was a member of ABC efflux pumps, and the protein was named RanB.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Aminoglicosídeos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Proteínas de Membrana Transportadoras/genética , Riemerella/efeitos dos fármacos , Solventes/farmacologia , Transportadores de Cassetes de Ligação de ATP/classificação , Animais , Patos/microbiologia , Deleção de Genes , Genes MDR/genética , Testes de Sensibilidade Microbiana , Compostos Orgânicos/farmacologia , Doenças das Aves Domésticas/microbiologia , Riemerella/genética , Riemerella/patogenicidade , Deleção de Sequência , Solventes/química
9.
BMC Infect Dis ; 20(1): 312, 2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32345218

RESUMO

BACKGROUND: While there is increasing knowledge about the gut microbiome, the factors influencing and the significance of the gut resistome are still not well understood. Infant gut commensals risk transferring multidrug-resistant antibiotic resistance genes (ARGs) to pathogenic bacteria. The rapid spread of multidrug-resistant pathogenic bacteria is a worldwide public health concern. Better understanding of the naïve infant gut resistome may build the evidence base for antimicrobial stewardship in both humans and in the food industry. Given the high carriage rate of extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Asia, we aimed to evaluate community prevalence, dynamics, and longitudinal changes in antibiotic resistance gene (ARG) profiles and prevalence of ESBL-producing E. coli and K. pneumoniae in the intestinal microbiome of infants participating in the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) study, a longitudinal cohort study of pregnant women and their infants. METHODS: We analysed ARGs in the first year of life among 75 infants at risk of eczema who had stool samples collected at multiple timepoints using metagenomics. RESULTS: The mean number of ARGs per infant increased with age. The most common ARGs identified confer resistance to aminoglycoside, beta-lactam, macrolide and tetracycline antibiotics; all infants harboured these antibiotic resistance genes at some point in the first year of life. Few ARGs persisted throughout the first year of life. Beta-lactam resistant Escherichia coli and Klebsiella pneumoniae were detected in 4 (5.3%) and 32 (42.7%) of subjects respectively. CONCLUSION: In this longitudinal cohort study of infants living in a region with high endemic antibacterial resistance, we demonstrate that majority of the infants harboured several antibiotic resistance genes in their gut and showed that the infant gut resistome is diverse and dynamic over the first year of life.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Eczema/diagnóstico , Microbioma Gastrointestinal/efeitos dos fármacos , Aminoglicosídeos/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Eczema/etiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Escherichia coli/isolamento & purificação , Fezes/microbiologia , Feminino , Humanos , Lactente , Recém-Nascido , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/isolamento & purificação , Estudos Longitudinais , Masculino , Risco , beta-Lactamases/genética , beta-Lactamases/metabolismo , beta-Lactamas/farmacologia
10.
Int J Infect Dis ; 93: 320-328, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32147539

RESUMO

OBJECTIVE: Phenotypic (Sensititre Myco, pDST) and genotypic drug susceptibility testing (GenoType NTM DR, gDST) in M. avium complex (MAC) have become available as standardized assays, but comparable data is needed. This study aimed to investigate the phenotypic and genotypic drug susceptibility patterns in MAC clinical isolates. METHODS: Overall, 98 isolates from 85 patients were included. pDST and gDST were performed on all isolates and results compared regarding specificity and sensitivity using pDST as a reference method. The impact of drug instability on pDST results was studied using a biological assay over 14 days. In addition, the evolution of antimicrobial resistance was investigated in sequential isolates of 13 patients. RESULTS: Macrolide resistance was rare, 1.2% (95% CI 0.7-7.3) of isolates in the base cohort. No aminoglycoside resistances were found, but 14.1% of the studied isolates (95% CI 7.8-23.8) showed intermediate susceptibility. The GenoType NTM DR identified two out of four macrolide-resistant isolates. Antibiotic stability was demonstrated to be poor in rifampicin, rifabutin, and doxycycylin. CONCLUSIONS: pDST results in NTM for unstable antibiotics must be interpreted with care. A combination of pDST and gDST will be useful for the guidance of antimicrobial therapy in MAC-disease.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Complexo Mycobacterium avium/efeitos dos fármacos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Aminoglicosídeos/farmacologia , Criança , Pré-Escolar , Estudos de Coortes , Genótipo , Humanos , Lactente , Macrolídeos/farmacologia , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Complexo Mycobacterium avium/genética , Complexo Mycobacterium avium/isolamento & purificação , Infecção por Mycobacterium avium-intracellulare/microbiologia , Fenótipo , Rifampina , Adulto Jovem
11.
Nat Commun ; 11(1): 1199, 2020 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-32139686

RESUMO

To tackle the global antibiotic resistance crisis, antibiotic resistance acquired either vertically by chromosomal mutations or horizontally through antibiotic resistance genes (ARGs) have been studied. Yet, little is known about the interactions between the two, which may impact the evolution of antibiotic resistance. Here, we develop a multiplexed barcoded approach to assess the fitness of 144 mutant-ARG combinations in Escherichia coli subjected to eight different antibiotics at 11 different concentrations. While most interactions are neutral, we identify significant interactions for 12% of the mutant-ARG combinations. The ability of most ARGs to confer high-level resistance at a low fitness cost shields the selective dynamics of mutants at low drug concentrations. Therefore, high-fitness mutants are often selected regardless of their resistance level. Finally, we identify strong negative epistasis between two unrelated resistance mechanisms: the tetA tetracycline resistance gene and loss-of-function nuo mutations involved in aminoglycoside tolerance. Our study highlights important constraints that may allow better prediction and control of antibiotic resistance evolution.


Assuntos
Resistência Microbiana a Medicamentos/genética , Epistasia Genética , Mutação/genética , Aminoglicosídeos/farmacologia , Sequência de Bases , Permeabilidade da Membrana Celular/efeitos dos fármacos , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Epistasia Genética/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Proteínas de Membrana Transportadoras/metabolismo , Estreptomicina/farmacologia
12.
Emerg Microbes Infect ; 9(1): 639-650, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32192413

RESUMO

Acinetobacter baumannii, a Gram-negative opportunistic pathogen, is a leading cause of hospital- and community-acquired infections. Acinetobacter baumannii can rapidly acquire diverse resistance mechanisms and undergo genetic modifications that confer resistance and persistence to all currently used clinical antibiotics. In this study, we found exogenous L-lysine sensitizes Acinetobacter baumannii, other Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and a Gram-positive bacterium (Mycobacterium smegmatis) to aminoglycosides. Importantly, the combination of L-lysine with aminoglycosides killed clinically isolated multidrug-resistant Acinetobacter baumannii and persister cells. The exogenous L-lysine can increase proton motive force via transmembrane chemical gradient, resulting in aminoglycoside acumination that further accounts for reactive oxygen species production. The combination of L-lysine and antibiotics highlights a promising strategy against bacterial infection.


Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Lisina/farmacologia , Acinetobacter baumannii/metabolismo , Ciclo do Ácido Cítrico , Farmacorresistência Bacteriana Múltipla , Sinergismo Farmacológico , Escherichia coli/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Klebsiella pneumoniae/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Mycobacterium smegmatis/efeitos dos fármacos , Força Próton-Motriz/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
13.
mBio ; 11(1)2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-32047133

RESUMO

Bacterial persisters exhibit noninherited antibiotic tolerance and are linked to the recalcitrance of bacterial infections. It is very urgent but also challenging to develop antipersister strategies. Here, we report that 10-s freezing with liquid nitrogen dramatically enhances the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many Gram-negative pathogens, with weaker potentiation effects on Gram-positive bacteria. In particular, antibiotic-tolerant Escherichia coli and Pseudomonas aeruginosa persisters-which were prepared by treating exponential-phase cells with ampicillin, ofloxacin, the protonophore cyanide m-chlorophenyl hydrazone (CCCP), or bacteriostatic antibiotics-can be effectively killed. We demonstrated, as a proof of concept, that freezing potentiated the aminoglycosides' killing of P. aeruginosa persisters in a mouse acute skin wound model. Mechanistically, freezing dramatically increased the bacterial uptake of aminoglycosides regardless of the presence of CCCP, indicating that the effects are independent of the proton motive force (PMF). In line with these results, we found that the effects were linked to freezing-induced cell membrane damage and were attributable, at least partly, to the mechanosensitive ion channel MscL, which was able to directly mediate such freezing-enhanced aminoglycoside uptake. In view of these results, we propose that the freezing-induced aminoglycoside potentiation is achieved by freezing-induced cell membrane destabilization, which, in turn, activates the MscL channel, which is able to effectively take up aminoglycosides in a PMF-independent manner. Our work may pave the way for the development of antipersister strategies that utilize the same mechanism as freezing but do so without causing any injury to animal cells.IMPORTANCE Antibiotics have long been used to successfully kill bacterial pathogens, but antibiotic resistance/tolerance usually has led to the failure of antibiotic therapy, and it has become a severe threat to human health. How to improve the efficacy of existing antibiotics is of importance for combating antibiotic-resistant/tolerant pathogens. Here, we report that 10-s rapid freezing with liquid nitrogen dramatically enhanced the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many bacterial pathogens in vitro and also in a mouse skin wound model. In particular, such combined treatment was able to effectively kill persister cells of Escherichia coli and Pseudomonas aeruginosa, which are per se tolerant of conventional treatment with bactericidal antibiotics for several hours. We also demonstrated that freezing-induced aminoglycoside potentiation was apparently linked to freezing-induced cell membrane damage that may have activated the mechanosensitive ion channel MscL, which, in turn, was able to effectively uptake aminoglycoside antibiotics in a proton motive force-independent manner. Our report sheds light on the development of a new strategy against bacterial pathogens by combining existing antibiotics with a conventional physical treatment or with MscL agonists.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Congelamento , Aminoglicosídeos/química , Animais , Bactérias/crescimento & desenvolvimento , Biofilmes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Proteínas de Escherichia coli/metabolismo , Canais Iônicos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos ICR , Testes de Sensibilidade Microbiana , Nitrogênio/farmacologia , Força Próton-Motriz , Pseudomonas aeruginosa/efeitos dos fármacos , Pele/efeitos dos fármacos , Pele/microbiologia
14.
Oncol Rep ; 43(3): 851-863, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32020213

RESUMO

Efficient enrichment and transmembrane transport of cytotoxic reagents are considered to be effective strategies to increase the efficiency and selectivity of antitumor drugs targeting solid tumors. In the present study, a recombinant protein ABD­LDP­Ec consisting of the albumin­binding domain (ABD), the apoprotein (LDP) of lidamycin (LDM) and an EGFR­targeting oligopeptide (Ec) was prepared by DNA recombination and bacterial fermentation, and was integrated with the enediyne chromophore (AE) of lidamycin to generate its enediyne­integrated analogue ABD­LDP­Ec­AE. ABD­LDP­Ec exhibited high binding capacity to both albumin and EGFR­positive pancreatic cancer cells, and was internalized into the cytoplasm through receptor­mediated endocytosis and albumin­driven macropinocytosis of K­ras mutant cells. In animal experiments, ABD­LDP­Ec demonstrated notable selective distribution in pancreatic carcinoma xenografts by passive targeting of albumin captured in the blood and was retained in the tumor for 48 h. ABD­LDP­Ec and ABD­LDP­Ec­AE exhibited inhibitory activity in cell proliferation and AsPC­1 xenograft growth, and ABD­LDP­Ec­AE increased the tumor growth inhibition rate by 20% compared with natural LDM. The results indicated that the introduction of ABD­based multi­functional drug delivery may be an effective approach to improve the efficacy of antitumor drugs, especially for K­ras mutant cancers.


Assuntos
Antineoplásicos/farmacologia , Neoplasias Pancreáticas/tratamento farmacológico , Peptídeos/antagonistas & inibidores , Proteínas Proto-Oncogênicas p21(ras)/genética , Albuminas/química , Albuminas/genética , Aminoglicosídeos/química , Aminoglicosídeos/genética , Aminoglicosídeos/farmacologia , Animais , Antineoplásicos/química , Linhagem Celular Tumoral , Enedi-Inos/química , Enedi-Inos/farmacologia , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/genética , Xenoenxertos , Humanos , Camundongos , Mutação/genética , Oligopeptídeos/química , Oligopeptídeos/genética , Oligopeptídeos/farmacologia , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Peptídeos/genética , Ligação Proteica/efeitos dos fármacos , Domínios Proteicos/genética , Proteínas Recombinantes/efeitos dos fármacos , Proteínas Recombinantes/genética , Ensaios Antitumorais Modelo de Xenoenxerto
15.
J Recept Signal Transduct Res ; 40(1): 77-88, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31971048

RESUMO

Adenosine deaminase (ADA) is an enzyme present in purine metabolic pathway. Its inhibitors are considered to be potent drug lead compounds against inflammatory and malignant diseases. This study aimed to test ADA inhibitory activity of some Streptomyces secondary metabolites by using computational and in vitro methods. The in silico screening of the inhibitory properties has been carried out using pharmacophore modeling, docking, and molecular dynamics studies. The in vitro validation of the selected antibiotics has been carried out by enzyme kinetics and fluorescent spectroscopic studies. The results indicated that novobiocin, an aminocoumarin antibiotic from Streptomyces niveus, has significant inhibition on ADA activity. Hence, the antibiotic can be used as a lead compound for the development of potential ADA inhibitors.


Assuntos
Inibidores de Adenosina Desaminase/farmacologia , Adenosina Desaminase/metabolismo , Antibacterianos/farmacologia , Reposicionamento de Medicamentos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Streptomyces/química , Inibidores de Adenosina Desaminase/química , Aminoglicosídeos/química , Aminoglicosídeos/farmacologia , Domínio Catalítico , Avaliação Pré-Clínica de Medicamentos , Ensaios Enzimáticos , Humanos , Análise dos Mínimos Quadrados , Ligantes , Novobiocina/química , Novobiocina/farmacologia , Relação Quantitativa Estrutura-Atividade , Espectrometria de Fluorescência
16.
Mol Biol Rep ; 47(3): 1703-1712, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31989429

RESUMO

The aim of this study was isolation and identification of the high-level aminoglycoside-resistant (HLAR) enterococci in raw milk and dairy products and to analyze their antibiotic resistance and the presence of aminoglycoside-modifying enzyme (AME) genes. A total of 59 HLAR enterococci were isolated from raw milk and traditional cheese samples. Thirty-nine of the 59 HLAR enterococci were isolated on streptomycin-containing agar medium, while the other 20 HLAR strains were isolated on gentamicin containing agar medium. The 59 HLAR enterococci were identified as 26 E. faecalis (44.07%), 18 E. faecium (30.51%), 13 E. durans (22.03%), and two E. gallinarum (3.39%) by species-specific PCR. Disk diffusion tests showed that teicoplanin were the most effective antibiotics used in this study, while 89.83% of isolates were found to be resistant to tetracycline. High rates of multiple antibiotic resistance were detected in HLAR isolates. Minimum inhibitory concentration (MIC) values of HLAR enterococci against streptomycin and gentamicin were found in the range of 64 to > 4096 µg/mL. Forty-seven (79.66%) of the 59 HLAR enterococci were found to be both high-level streptomycin-resistant (HLSR) and high-level gentamicin-resistant (HLGR) by MIC tests. However, no correlation was found between the results of the disk diffusion and MIC tests for gentamicin and streptomycin in some HLAR strains. The aph(3')-IIIa (94.92%) was found to be most prevalent AME gene followed by ant(4')-Ia (45.76%), ant(6')-Ia (20.34%) and aph(2'')-Ic (10.17%). None of the isolates contained the aac(6')-Ie-aph(2'')-Ia, aph(2'')-Ib or aph(2'')-Id genes. None of the AME-encoding genes were identified in E. durans RG20.1, E. faecalis RG22.4, or RG26.1. In conclusion, HLAR enterococci strains isolated in this study may act as reservoirs in the dissemination of antibiotic resistance genes.


Assuntos
Aminoglicosídeos/farmacologia , Proteínas de Bactérias/genética , Queijo/microbiologia , Farmacorresistência Bacteriana/genética , Farmacorresistência Bacteriana Múltipla/genética , Enterococcus/genética , Leite/microbiologia , Animais , Proteínas de Bactérias/metabolismo , Enterococcus/classificação , Enterococcus/metabolismo , Gentamicinas/farmacologia , Humanos , Canamicina Quinase/genética , Canamicina Quinase/metabolismo , Testes de Sensibilidade Microbiana/métodos , Estreptomicina/farmacologia , Teicoplanina/farmacologia , Turquia
17.
mBio ; 11(1)2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31911486

RESUMO

Carbon metabolism plays an essential role in bacterial pathogenesis and susceptibility to antibiotics. In Pseudomonas aeruginosa, Crc, Hfq, and a small RNA, CrcZ, are central regulators of carbon metabolism. By screening mutants of genes involved in carbon metabolism, we found that mutation of the tpiA gene reduces the expression of the type III secretion system (T3SS) and bacterial resistance to aminoglycoside antibiotics. TpiA is a triosephosphate isomerase that reversibly converts glyceraldehyde 3-phosphate to dihydroxyacetone phosphate, a key step connecting glucose metabolism with glycerol and phospholipid metabolisms. We found that mutation of the tpiA gene enhances the bacterial carbon metabolism, respiration, and oxidative phosphorylation, which increases the membrane potential and promotes the uptake of aminoglycoside antibiotics. Further studies revealed that the level of CrcZ is increased in the tpiA mutant due to enhanced stability. Mutation of the crcZ gene in the tpiA mutant background restored the expression of the T3SS genes and the bacterial resistance to aminoglycoside antibiotics. Overall, this study reveals an essential role of TpiA in the metabolism, virulence, and antibiotic resistance in P. aeruginosa IMPORTANCE The increase in bacterial resistance against antibiotics imposes a severe threat to public health. It is urgent to identify new drug targets and develop novel antimicrobials. Metabolic homeostasis of bacteria plays an essential role in their virulence and resistance to antibiotics. Recent studies demonstrated that antibiotic efficacies can be improved by modulating the bacterial metabolism. Pseudomonas aeruginosa is an important opportunistic human pathogen that causes various infections. The bacterium is intrinsically resistant to antibiotics. In this study, we provide clear evidence that TpiA (triosephosphate isomerase) plays an essential role in the metabolism of P. aeruginosa and influences bacterial virulence and antibiotic resistance. The significance of this work is in identifying a key enzyme in the metabolic network, which will provide clues as to the development of novel treatment strategies against infections caused by P. aeruginosa.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , RNA Bacteriano , Triose-Fosfato Isomerase/metabolismo , Repressão Catabólica/genética , Redes e Vias Metabólicas , Testes de Sensibilidade Microbiana , Modelos Biológicos , Mutação , Infecções por Pseudomonas/tratamento farmacológico , Triose-Fosfato Isomerase/genética , Sistemas de Secreção Tipo III/genética , Sistemas de Secreção Tipo III/metabolismo , Virulência , Fatores de Virulência/genética
18.
J Orthop Res ; 38(6): 1365-1374, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-31922274

RESUMO

Infectious arthritis is difficult to treat in both human and veterinary clinical practice. Recent literature reports Staphylococcus aureus as well as other gram-positive and gram-negative isolates forming free-floating biofilms in both human and equine synovial fluid that are tolerant to traditional antimicrobial therapy. Using an in vitro equine model, we investigated the ability of platelet-rich plasma (PRP) formulations to combat synovial fluid biofilm aggregates. Synovial fluid was infected, and biofilm aggregates allowed to form over a 2-hour period. PRP was collected and processed into different formulations by platelet concentration, leukocyte presence, and activation or lysis. Infected synovial fluid was treated with different PRP formulations with or without aminoglycoside cotreatment. Bacterial load (colony-forming unit/mL) was determined by serial dilutions and plate counting at 8 hours posttreatment. All PRP formulations displayed antimicrobial properties; however, formulations containing higher concentrations of platelets without leukocytes had increased antimicrobial activity. Lysis of PRP and pooling of the PRP lysate (PRP-L) from multiple horses as compared to individual horses further increased antimicrobial activity. This activity was lost with the removal of the plasma component or inhibition of the proteolytic activity within the plasma. Fractionation of pooled PRP-L identified the bioactive components to be cationic and low-molecular weight (<10 kDa). Overall, PRP-L exhibited synergism with amikacin against aminoglycoside tolerant biofilm aggregates with greater activity against gram-positive bacteria. In conclusion, the use of PRP-L has the potential to augment current antimicrobial treatment regimens which could lead to a decrease in morbidity and mortality associated with infectious arthritis.


Assuntos
Antibacterianos/farmacologia , Artrite Infecciosa/tratamento farmacológico , Biofilmes , Plasma Rico em Plaquetas , Líquido Sinovial/microbiologia , Aminoglicosídeos/farmacologia , Animais , Biofilmes/efeitos dos fármacos , Feminino , Cavalos , Masculino , Peso Molecular
19.
Appl Microbiol Biotechnol ; 104(5): 1955-1976, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31970432

RESUMO

Aminoglycosides are one of the common classes of antibiotics that have been widely used for treating infections caused by pathogenic bacteria. The mechanism of bactericidal action by aminoglycosides is well-known, by which it terminates the cytoplasmic protein synthesis. However, the potentials of aminoglycosides become hindered when facing the evolution of bacterial resistance mechanisms. Among multiple resistance mechanisms displayed by bacteria against antibiotics, the formation of biofilm is the mechanism that provides a barrier for antibiotics to reach the cellular level. Bacteria present in the biofilm also get protection against the impact of host immune responses, harsh environmental conditions, and other antimicrobial treatments. Hence, with the multifaceted resistance developed by biofilm-forming pathogenic bacteria, antibiotics are therefore discontinued for further applications. However, the recent research developed several alternative strategies such as optimization of the active concentration, modification of the environmental conditions, modification of the chemical structure, combinatorial application with other active agents, and formulation with biocompatible carrier materials to revitalize and exploit the new potential of aminoglycosides. The present review article describes the above mentioned multiple approaches and possible mechanisms for the application of aminoglycosides to treat biofilm-associated infections.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Adjuvantes Farmacêuticos/química , Adjuvantes Farmacêuticos/farmacologia , Adjuvantes Farmacêuticos/uso terapêutico , Aminoglicosídeos/química , Aminoglicosídeos/uso terapêutico , Antibacterianos/química , Antibacterianos/uso terapêutico , Bactérias/crescimento & desenvolvimento , Bactérias/patogenicidade , Infecções Bacterianas/tratamento farmacológico , Biofilmes/crescimento & desenvolvimento , Portadores de Fármacos/química , Portadores de Fármacos/farmacologia , Portadores de Fármacos/uso terapêutico , Farmacorresistência Bacteriana , Quimioterapia Combinada , Humanos , Fatores de Virulência/metabolismo
20.
Int J Antimicrob Agents ; 55(3): 105882, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923570

RESUMO

This study aimed to assess the clinical impact and potential risk factors associated with polymyxin-resistant Enterobacteriaceae strains isolated from patients hospitalized in adult and neonatal intensive care units. A case-control study was conducted from September 2015 to January 2017. Antimicrobial susceptibility of polymyxin-resistant Enterobacteriaceae strains was determined by broth microdilution. The presence of resistance genes was evaluated by polymerase chain reaction and DNA sequencing. Renal failure [P=0.02, odds ratio (OR) 11.37, 95% confidence interval (CI) 1.0-128.63], use of a urinary catheter (P<0.01, OR 4.16, 95% CI 38.82-366.07), transfer between hospital units (P=0.03, OR 9.98, 95% CI 1.01-98.42), carbapenem use (P<0.01, OR 45.49, 95% CI 6.93-298.62) and surgical procedure (P<0.01, OR 16.52, 95% CI 2.83-96.32) were found to be risk factors for the acquisition of polymyxin-resistant strains in adult patients. For neonatal patients, use of a central venous catheter (P<0.01, OR 69.59, 95% CI 7.33-660.30) was the only risk factor associated with the acquisition of polymyxin-resistant strains. Analysis of the outcomes revealed that the mortality rate was significantly higher in adult (66.6%) and neonatal (23.5%) patients with polymyxin-resistant strains than in those with polymyxin-susceptible strains. In addition, carbapenem exposure (P<0.01, OR 50.93, 95% CI 2.26->999.999) was strongly associated with mortality. On the other hand, aminoglycoside use (P<0.03, OR 0.06, 95% CI 0.004-0.97) was a protective factor against mortality from polymyxin-resistant strains. Several risk factors were associated with polymyxin-resistant strains. The high mortality rates showed that acquisition of these strains is a predictor for unfavourable outcomes. Combination treatment with an aminoglycoside and polymyxin might be a better combination to improve patient outcomes.


Assuntos
Antibacterianos/farmacologia , Enterobacteriáceas Resistentes a Carbapenêmicos , Infecções por Enterobacteriaceae , Polimixinas/farmacologia , Aminoglicosídeos/farmacologia , Aminoglicosídeos/uso terapêutico , Antibacterianos/uso terapêutico , Carbapenêmicos/farmacologia , Carbapenêmicos/uso terapêutico , Estado Terminal/epidemiologia , Infecções por Enterobacteriaceae/epidemiologia , Infecções por Enterobacteriaceae/fisiopatologia , Humanos , Fatores de Risco
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA