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1.
Nat Commun ; 11(1): 4915, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004811

RESUMO

A phenotype of Escherichia coli and Klebsiella pneumoniae, resistant to piperacillin/tazobactam (TZP) but susceptible to carbapenems and 3rd generation cephalosporins, has emerged. The resistance mechanism associated with this phenotype has been identified as hyperproduction of the ß-lactamase TEM. However, the mechanism of hyperproduction due to gene amplification is not well understood. Here, we report a mechanism of gene amplification due to a translocatable unit (TU) excising from an IS26-flanked pseudo-compound transposon, PTn6762, which harbours blaTEM-1B. The TU re-inserts into the chromosome adjacent to IS26 and forms a tandem array of TUs, which increases the copy number of blaTEM-1B, leading to TEM-1B hyperproduction and TZP resistance. Despite a significant increase in blaTEM-1B copy number, the TZP-resistant isolate does not incur a fitness cost compared to the TZP-susceptible ancestor. This mechanism of amplification of blaTEM-1B is an important consideration when using genomic data to predict susceptibility to TZP.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Infecções por Escherichia coli/tratamento farmacológico , Proteínas de Escherichia coli/genética , Escherichia coli/genética , beta-Lactamases/genética , Antibacterianos/uso terapêutico , Cromossomos Bacterianos/genética , Elementos de DNA Transponíveis/genética , DNA Bacteriano/genética , Quimioterapia Combinada/métodos , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Amplificação de Genes , Regulação Bacteriana da Expressão Gênica , Genoma Bacteriano/genética , Humanos , Testes de Sensibilidade Microbiana , Piperacilina/farmacologia , Piperacilina/uso terapêutico , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , Tazobactam/farmacologia , Tazobactam/uso terapêutico , Sequenciamento Completo do Genoma
2.
AAPS PharmSciTech ; 21(7): 286, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33063151

RESUMO

The CoViD-19 pandemic has caused a sudden spike in demand and production of hand sanitisers. Concerns are rising regarding the quality of such products, as the safeguard of consumers is a priority worldwide. We analyse here the ethanolic content of seven off-the-shelf hand sanitiser gels (two biocides and five cosmetics) from the Italian market, using gas chromatography. The WHO recommends that products containing ethanol should have 60-95% (v/v) alcohol. Four of the tested hand gels have ethanolic contents within the recommended range, while three products (all cosmetics) contain < 60% (v/v), i.e. 52.1% (w/w), ethanol. The product with the lowest alcoholic content has 37.1% w/w ethanol. Toxic methanol is not found in any of the hand sanitisers. We show, in addition, that products with the highest ethanolic content have generally greater antibacterial activity. In conclusion, all tested products are complying with the EU regulations, as the three "substandard" products are classified as cosmetics, whose purpose is cleaning and not disinfecting. Nevertheless, if such hand cleaners were inappropriately used as hand disinfectants, they might be ineffective. Thus, consumer safety relays on awareness and ability to distinguish between biocidal and cosmetics hand gels. The obtained results might sensitise the scientific community, health agencies and ultimately consumers towards the risks of using hand sanitisers of substandard alcoholic concentration. If the wrong product is chosen by consumers, public health can be compromised by the inappropriate use of "low-dosed" cosmetic gels as disinfectants, particularly during the period of the CoViD-19 pandemic.


Assuntos
Infecções por Coronavirus , Higienizadores de Mão/análise , Pandemias , Pneumonia Viral , Antibacterianos/análise , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Cromatografia Gasosa , Cosméticos , Escherichia coli/efeitos dos fármacos , Etanol/análise , Europa (Continente) , Géis , Desinfecção das Mãos , Higienizadores de Mão/farmacologia , Higienizadores de Mão/normas , Metanol/análise , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacos
3.
Nat Commun ; 11(1): 4648, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938927

RESUMO

Emergence of tigecycline-resistance tet(X) gene orthologues rendered tigecycline ineffective as last-resort antibiotic. To understand the potential origin and transmission mechanisms of these genes, we survey the prevalence of tet(X) and its orthologues in 2997 clinical E. coli and K. pneumoniae isolates collected nationwide in China with results showing very low prevalence on these two types of strains, 0.32% and 0%, respectively. Further surveillance of tet(X) orthologues in 3692 different clinical Gram-negative bacterial strains collected during 1994-2019 in hospitals in Zhejiang province, China reveals 106 (2.7%) tet(X)-bearing strains with Flavobacteriaceae being the dominant (97/376, 25.8%) bacteria. In addition, tet(X)s are found to be predominantly located on the chromosomes of Flavobacteriaceae and share similar GC-content as Flavobacteriaceae. It also further evolves into different orthologues and transmits among different species. Data from this work suggest that Flavobacteriaceae could be the potential ancestral source of the tigecycline resistance gene tet(X).


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana/genética , Infecções por Flavobacteriaceae/epidemiologia , Flavobacteriaceae/genética , Tigeciclina/farmacologia , China/epidemiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Evolução Molecular , Flavobacteriaceae/efeitos dos fármacos , Flavobacteriaceae/isolamento & purificação , Infecções por Flavobacteriaceae/microbiologia , Humanos , Filogenia
4.
BMC Infect Dis ; 20(1): 673, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938424

RESUMO

BACKGROUND: Urinary tract infection is one of the most common bacterial infections in children. Understanding the characteristics of uropathogens and their antimicrobial susceptibility pattern in a particular setting can provide evidence for the appropriate management of cases. This study aimed to assess the bacterial profile of urinary tract infection, their antimicrobial susceptibility pattern and associated factors among clinically suspected children attending at Felege-Hiwot Comprehensive Specialized Hospital, Northwest Ethiopia. METHODS: A hospital-based cross-sectional study was conducted from February-April, 2019. A systematic sampling technique was employed. A mid-stream urine sample was inoculated on cystine lactose electrolyte deficient media and incubated for 24-48 h. Sub-culturing was done on Mac-Conkey and blood agar. Antimicrobial susceptibility test was done on Muller-Hinton agar. A binary logistic regression model was used to see the association between dependent and independent factors. A p-value< 0.05 at 95% CI was considered as statistically significant. RESULTS: The overall prevalence of urinary tract infection was 16.7% (95% CI 12.4-21.1). Both Gram-negative and Gram-positive bacterial isolates were recovered with a rate of 44/50 (88%) and 6/50 (12%) respectively. Among Gram-negative isolates, E. coli 28/44(63.6%) was predominant while S. saprophyticus 2/6(33.3%) was prevalent among Gram-positive bacterial isolates. Overall, a high level of resistance to ampicillin, augmentin, and tetracycline was shown by Gram-negative bacteria with a rate of 44/44(100%), 39/44(88.6%), and36/44 (81.8%) respectively. About 33/50(66%) of overall multidrug resistance was observed (95% CI 52-78). About six Gram-negative bacterial isolates were extended spectrum beta-lactamase (ESBL) producers. Having a history of urinary tract infection (P-0.003, AOR 1.86-22.15) and male uncircumcision (p-0.00, AOR 5.5-65.35) were the independent variables that associate for urinary tract infections. CONCLUSION: In the present study, the prevalence of urinary tract infection among children was high and considerably a high proportion of multidrug resistance was observed. This result will have a significant impact on the selection of appropriate antimicrobial agents for the treatment of urinary tract infection.


Assuntos
Infecções Urinárias/diagnóstico , Adolescente , Antibacterianos/farmacologia , Criança , Pré-Escolar , Estudos Transversais , Farmacorresistência Bacteriana Múltipla , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Etiópia/epidemiologia , Feminino , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/isolamento & purificação , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/isolamento & purificação , Hospitais , Humanos , Lactente , Masculino , Testes de Sensibilidade Microbiana , Razão de Chances , Estudos Prospectivos , Infecções Urinárias/microbiologia , beta-Lactamases/genética , beta-Lactamases/metabolismo
5.
PLoS One ; 15(9): e0236442, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32925914

RESUMO

The goal of this study was to determine the frequency of resistance to extended-spectrum cephalosporins (ESCs) in Escherichia coli and other Enterobacterales from turkeys in Canada and characterize the associated resistance determinants. Pooled fecal samples were collected in 77 turkey farms across British Columbia, Québec, and Ontario. Isolates were obtained with and without selective enrichment cultures and compared to isolates from diagnostic submissions of suspected colibacillosis cases in Ontario. Isolates were identified using MALDI-TOF and susceptibility to ESCs was assessed by disk diffusion. The presence of blaCMY, blaCTX-M, blaTEM, and blaSHV was tested by PCR. Transformation experiments were used to characterize blaCMY plasmids. Genome sequencing with short and long reads was performed on a representative sample of blaCTX-M-positive isolates to assess isolates relatedness and characterize blaCTX-M plasmids. For the positive enrichment cultures (67% of total samples), 93% (587/610) were identified as E. coli, with only a few other Enterobacterales species identified. The frequency of ESC resistance was low in E. coli isolates from diagnostic submission (4%) and fecal samples without selective enrichment (5%). Of the ESC-resistant Enterobacterales isolates from selective enrichments, 71%, 18%, 14%, and 8% were positive for blaCMY, blaTEM, blaCTX-M, and blaSHV, respectively. IncI1 followed by IncK were the main incompatibility groups identified for blaCMY plasmids. The blaCTX-M-1 gene was found repeatedly on IncI1 plasmids of the pMLST type 3, while blaCTX-M-15, blaCTX-M-55, and blaCTX-M-65 were associated with a variety of IncF plasmids. Clonal spread of strains carrying blaCTX-M genes between turkey farms was observed, as well as the presence of an epidemic blaCTX-M-1 plasmid in unrelated E. coli strains. In conclusion, Enterobacterales resistant to ESCs were still widespread at low concentration in turkey feces two years after the cessation of ceftiofur use. Although blaCMY-2 is the main ESC resistance determinant in E. coli from Canadian turkeys, blaCTX-M genes also occur which are often carried by multidrug resistance plasmids. Both clonal spread and horizontal gene transfer are involved in parallel in the spread of blaCTX-M genes in Enterobacterales from Canadian turkeys.


Assuntos
Antibacterianos/farmacologia , Cefalosporinas/farmacologia , Infecções por Enterobacteriaceae/veterinária , Enterobacteriaceae/efeitos dos fármacos , Doenças das Aves Domésticas/tratamento farmacológico , Perus/microbiologia , Animais , Antibacterianos/uso terapêutico , Cefalosporinas/uso terapêutico , Farmacorresistência Bacteriana , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Infecções por Enterobacteriaceae/tratamento farmacológico , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Doenças das Aves Domésticas/microbiologia
6.
Nat Commun ; 11(1): 4450, 2020 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-32895379

RESUMO

Hollow multishelled structures (HoMSs), with relatively isolated cavities and hierarchal pores in the shells, are structurally similar to cells. Functionally inspired by the different transmission forms in living cells, we studied the mass transport process in HoMSs in detail. In the present work, after introducing the antibacterial agent methylisothiazolinone (MIT) as model molecules into HoMSs, we discover three sequential release stages, i.e., burst release, sustained release and stimulus-responsive release, in one system. The triple-shelled structure can provide a long sterility period in a bacteria-rich environment that is nearly 8 times longer than that of the pure antimicrobial agent under the same conditions. More importantly, the HoMS system provides a smart responsive release mechanism that can be triggered by environmental changes. All these advantages could be attributed to chemical diffusion- and physical barrier-driven temporally-spatially ordered drug release, providing a route for the design of intelligent nanomaterials.


Assuntos
Antibacterianos/administração & dosagem , Preparações de Ação Retardada/administração & dosagem , Portadores de Fármacos/química , Nanoestruturas/química , Antibacterianos/farmacocinética , Preparações de Ação Retardada/farmacocinética , Difusão , Composição de Medicamentos/métodos , Liberação Controlada de Fármacos , Escherichia coli/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Microesferas , Tiazóis/administração & dosagem , Tiazóis/farmacocinética
7.
Int J Nanomedicine ; 15: 6433-6449, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32922010

RESUMO

Background: Electrospun nanofibers based on Colocasia esculenta tuber (CET) protein are considered as a promising material for wound dressing applications. However, the use of these nanofibers in aqueous conditions has poor stability. The present study was performed to obtain insights into the crosslinked electrospun CET's protein-chitosan (CS)-poly(ethylene oxide) (PEO) nanofibers and to evaluate their potential for wound dressing applications. Methods: The electrospun nanofibers were crosslinked with glutaraldehyde (GA) vapor and heat treatment (HT) to enhance their physicochemical stability. The crosslinked nanofibers were characterized by protein profiles, morphology structures, thermal behavior, mechanical properties, and degradation behavior. Furthermore, the antibacterial properties and cytocompatibility were analyzed by antibacterial assessment and cell proliferation. Results: The protein profiles of the electrospun CET's protein-CS-PEO nanofibers before and after HT crosslinking contained one major bioactive protein with a molecular weight of 14.4 kDa. Scanning electron microscopy images of the crosslinked nanofibers indicated preservation of the structure after immersion in phosphate buffered saline. The crosslinked nanofibers resulted in higher ultimate tensile strength and lower ultimate strain compared to the non-crosslinked nanofibers. GA vapor crosslinking showed higher water stability compared to HT crosslinking. The in vitro antibacterial activity of the crosslinked nanofibers showed a stronger bacteriostatic effect on Staphylococcus aureus than on Escherichia coli. Human skin fibroblast cell proliferation on crosslinked GA vapor and HT nanofibers with 1% (w/v) CS and 2% (w/v) CET's protein demonstrated the highest among all the other crosslinked nanofibers after seven days of cell culture. Cell proliferation and cell morphology results revealed that introducing higher CET's protein concentration on crosslinked nanofibers could increase cell proliferation of the crosslinked nanofibers. Conclusion: These results are promising for the potential use of the crosslinked electrospun CET's protein-CS-PEO nanofibers as bioactive wound dressing materials.


Assuntos
Antibacterianos/farmacologia , Quitosana/química , Colocasia/química , Reagentes para Ligações Cruzadas/química , Nanofibras/química , Proteínas de Plantas/química , Tubérculos/química , Polietilenoglicóis/química , Animais , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Células NIH 3T3 , Nanofibras/ultraestrutura , Proteínas de Plantas/ultraestrutura , Staphylococcus aureus/efeitos dos fármacos , Estresse Mecânico , Temperatura
8.
Ecotoxicol Environ Saf ; 205: 111300, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32961492

RESUMO

Bacterial resistance caused by the abuse of antibiotics has attracted worldwide attention. However, there are few studies exploring bacterial resistance under the environmental exposure condition of antibiotics that is featured by low-dose and mixture. In this study, sulfonamides (SAs), sulfonamide potentiators (SAPs) and tetracyclines (TCs) were used to determine the effects of antibiotics on plasmid RP4 conjugative transfer of Escherichia coli (E. coli) under single or combined exposure, and the relationship between the effects of antibiotics on conjugative transfer and growth was investigated. The results show that the effects of single or binary antibiotics on plasmid RP4 conjugative transfer all exhibit a hormetic phenomenon. The linear regression reveals that the concentrations of the three antibiotics promoting conjugative transfer are correlated with the concentrations promoting growth and the physicochemical properties of the compounds. The combined effects of SAs-SAPs and SAs-TCs on plasmid conjugative transfer are mainly synergistic and antagonistic. While SAPs provide more effective concentrations for the promotion of conjugative transfer in SAs-SAPs mixtures, SAs play a more important role in promoting conjugative transfer in SAs-TCs mixtures. Mechanism explanation shows that SAs, SAPs and TCs inhibit bacterial growth by acting on their target proteins DHPS, DHFR and 30S ribosomal subunit, respectively. This study indicates that toxic stress stimulates the occurrence of conjugative transfer and promotes the development of bacterial resistance, which will provide a reference for resistance risk assessment of antibiotic exposure.


Assuntos
Antibacterianos/toxicidade , Conjugação Genética/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Escherichia coli/efeitos dos fármacos , Hormese , Plasmídeos , Antagonismo de Drogas , Sinergismo Farmacológico , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Plasmídeos/efeitos dos fármacos , Plasmídeos/genética , Sulfonamidas/toxicidade , Tetraciclinas/toxicidade
9.
Nature ; 584(7821): 479-483, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32788728

RESUMO

Lipopolysaccharide (LPS) resides in the outer membrane of Gram-negative bacteria where it is responsible for barrier function1,2. LPS can cause death as a result of septic shock, and its lipid A core is the target of polymyxin antibiotics3,4. Despite the clinical importance of polymyxins and the emergence of multidrug resistant strains5, our understanding of the bacterial factors that regulate LPS biogenesis is incomplete. Here we characterize the inner membrane protein PbgA and report that its depletion attenuates the virulence of Escherichia coli by reducing levels of LPS and outer membrane integrity. In contrast to previous claims that PbgA functions as a cardiolipin transporter6-9, our structural analyses and physiological studies identify a lipid A-binding motif along the periplasmic leaflet of the inner membrane. Synthetic PbgA-derived peptides selectively bind to LPS in vitro and inhibit the growth of diverse Gram-negative bacteria, including polymyxin-resistant strains. Proteomic, genetic and pharmacological experiments uncover a model in which direct periplasmic sensing of LPS by PbgA coordinates the biosynthesis of lipid A by regulating the stability of LpxC, a key cytoplasmic biosynthetic enzyme10-12. In summary, we find that PbgA has an unexpected but essential role in the regulation of LPS biogenesis, presents a new structural basis for the selective recognition of lipids, and provides opportunities for future antibiotic discovery.


Assuntos
Membrana Celular/química , Escherichia coli/química , Escherichia coli/patogenicidade , Lipopolissacarídeos/química , Lipopolissacarídeos/metabolismo , Amidoidrolases/química , Amidoidrolases/metabolismo , Motivos de Aminoácidos , Membrana Externa Bacteriana/química , Membrana Externa Bacteriana/metabolismo , Sítios de Ligação , Membrana Celular/metabolismo , Estabilidade Enzimática , Escherichia coli/citologia , Escherichia coli/efeitos dos fármacos , Genes Essenciais , Hidrolases/química , Hidrolases/metabolismo , Lipídeo A/química , Lipídeo A/metabolismo , Lipopolissacarídeos/biossíntese , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Modelos Moleculares , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Fragmentos de Peptídeos/farmacologia , Periplasma/química , Periplasma/metabolismo , Ligação Proteica , Virulência
10.
Nat Commun ; 11(1): 3834, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737309

RESUMO

The transcriptional inducer anhydrotetracycline (aTc) and the bacteriostatic antibiotic tetracycline (Tc) are commonly used in all fields of biology for control of transcription or translation. A drawback of these and other small molecule inducers is the difficulty of their removal from cell cultures, limiting their application for dynamic control. Here, we describe a simple method to overcome this limitation, and show that the natural photosensitivity of aTc/Tc can be exploited to turn them into highly predictable optogenetic transcriptional- and growth-regulators. This new optogenetic class uniquely features both dynamic and setpoint control which act via population-memory adjustable through opto-chemical modulation. We demonstrate this method by applying it for dynamic gene expression control and for enhancing the performance of an existing optogenetic system. We then expand the utility of the aTc system by constructing a new chemical bandpass filter that increases its aTc response range. The simplicity of our method enables scientists and biotechnologists to use their existing systems employing aTc/Tc for dynamic optogenetic experiments without genetic modification.


Assuntos
Escherichia coli/efeitos dos fármacos , Optogenética/métodos , Biossíntese de Proteínas/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Tetraciclina/farmacologia , Tetraciclinas/farmacologia , Transcrição Genética/efeitos dos fármacos , Clonagem Molecular , Relação Dose-Resposta a Droga , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Genes Reporter , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Fotólise , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Raios Ultravioleta
11.
Ecotoxicol Environ Saf ; 204: 111119, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32798757

RESUMO

The rapid spread of antibiotic resistance genes (ARGs) is a great challenge to the ecological safety and human health. The intestine of humans and animals is an important site for the increase and spread of ARGs due to the great diversity and abundance of microorganisms in the intestinal microecology. ARGs, including the intracellular (iARGs) and the extracellular (eARGs) ARGs, are usually introduced into the intestinal tract through the diet, and the iARGs are colonized and spread in the intestinal microbiota with the help of the host bacteria. However, whether the eARGs can enter the intestinal microorganisms in the absence of host bacteria is not known. Here, we show the transformation and the diffusion of the ampramycin resistance gene (Ap) carried by the free plasmid RK2 in the intestinal microbiota of mice. After two days of consecutive gavage with free RK2, the intracellular Ap gene increases from days 0-8 in the feces of mice, and has remained constant. Bacterial transformation happens in the small intestine, including proximal and distal jejuna and proximal and distal ilea, at the early stage (first two days), and the intracellular RK2 is diffused into the intestinal microbiota of mice by conjugation on days 2-8 day, which is based on the distribution of eARG and iARG and the mRNA expression levels of trbBp, trfAp, korA, korB, and trbA. The characteristics of ARGs susceptible microbiota for transformation are analyzed using 16s rRNA gene sequencing, transmission electron microscopy, and flow cytometric. The ingestion of RK2 affects the composition of intestinal microbiota especially for Proteobacteria, and the antibiotic residue promotes the increase in Escherichia coli. These findings are important to assess the risk of ARGs, especially the eARGs in the intestinal microecology.


Assuntos
Resistência Microbiana a Medicamentos/genética , Microbioma Gastrointestinal/fisiologia , Genes Bacterianos , Camundongos/microbiologia , Animais , Antibacterianos , Bactérias , Escherichia coli/efeitos dos fármacos , Fezes , Humanos , Intestinos , Microbiota , Plasmídeos , RNA Ribossômico 16S/genética
12.
PLoS One ; 15(8): e0228525, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822344

RESUMO

The toxic effect of strained hydrocarbon 2,2'-bis (bicyclo[2.2.1]heptane) (BBH) was studied using whole-cell bacterial lux-biosensors based on Escherichia coli cells in which luciferase genes are transcriptionally fused with stress-inducible promoters. It was shown that BBH has the genotoxic effect causing bacterial SOS response however no alkylating effect has been revealed. In addition to DNA damage, there is an oxidative effect causing the response of OxyR/S and SoxR/S regulons. The most sensitive to BBH lux-biosensor was E. coli pSoxS-lux which reacts to the appearance of superoxide anion radicals in the cell. It is assumed that the oxidation of BBH leads to the generation of reactive oxygen species, which provide the main contribution to the genotoxicity of this substance.


Assuntos
Compostos Bicíclicos com Pontes/toxicidade , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Mutagênicos/toxicidade , Alquilação/efeitos dos fármacos , Técnicas Biossensoriais , Dano ao DNA , Relação Dose-Resposta a Droga , Escherichia coli/citologia , Escherichia coli/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Regulon/efeitos dos fármacos , Regulon/genética
13.
Biomed Environ Sci ; 33(7): 471-483, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32807266

RESUMO

Objective: Owing to antibiotic abuse and the subsequent development of antibiotic resistance, bacterial infection has become one of the most persistent unresolved problems. New antibacterial agents, especially those that are environmental-friendly, are urgently needed. Methods: Melanin extracted by filtration centrifugation and acid and proteolytic hydrolysis was characterized using UV, FTIR, TEM, and XPS. Photothermal conversion was calculated, and the bacteriostatic effects, in vitro and in vivo, were assessed by plate counting and ratios (%) of wound areas. Results: Natural melanin hydrolyzed by trypsin had good photothermal conversion effects, which resulted in superior bacteriostatic activities. The extracted melanin along with laser NIR irradiation at 808 nm promoted the healing of wounds infected by drug-resistant bacteria in vivo and was biocompatible according to toxicity tests in vivo and in vitro. Conclusion: The present findings indicated a safe and efficient method of developing natural antibacterial agents.


Assuntos
Antibacterianos/farmacologia , Infecções por Escherichia coli/tratamento farmacológico , Melaninas/farmacologia , Mytilus edulis/química , Infecções Estafilocócicas/tratamento farmacológico , Cicatrização , Exoesqueleto/química , Animais , Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , Processos Fotoquímicos , Ratos , Ratos Sprague-Dawley , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/efeitos da radiação
14.
ACS Nano ; 14(9): 12045-12053, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32790338

RESUMO

Wearing face masks has been widely recommended to contain respiratory virus diseases, yet the improper use of masks poses a threat of jeopardizing the protection effect. We here identified the bacteria viability on common face masks and found that the majority of bacteria (90%) remain alive after 8 h. Using laser-induced graphene (LIG), the inhibition rate improves to ∼81%. Combined with the photothermal effect, 99.998% bacterial killing efficiency could be attained within 10 min. For aerosolized bacteria, LIG also showed superior antibacterial capacity. The LIG can be converted from a diversity of carbon precursors including biomaterials, which eases the supply stress and environmental pressure amid an outbreak. In addition, self-reporting of mask conditions is feasible using the moisture-induced electricity from gradient graphene. Our results improve the safe use of masks and benefit the environment.


Assuntos
Antibacterianos/farmacologia , Grafite/farmacologia , Lasers , Luz , Viabilidade Microbiana , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/fisiologia
15.
Int J Nanomedicine ; 15: 4991-5004, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764931

RESUMO

Introduction: Various materials and approaches have been used to reduce the mesh-induced inflammatory response and modify the mesh with tissue-matched mechanical properties, aiming to improve the repair of abdominal wall defects. Materials and Methods: In this study, we fabricated a polycaprolactone (PCL)/silk fibroin (SF) mesh integrated with amoxicillin (AMX)-incorporating multiwalled carbon nanotubes (MWCNTs) via electrospinning, grafting and crosslinking, developing a sustainable antibiotic and flexible mesh. AMX was loaded into the hollow tubular MWCNTs by physical adsorption, and a nanofibrous structure was constructed by electrospinning PCL and SF (40:60 w/w). The AMX@MWCNTs were then chemically grafted onto the surfaces of the PCL/SF nanofibers by treating with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) solution for simultaneous crosslinking and coating. The incorporation of AMX into the MWCNTs (AMX@MWCNTs) and the integration of the AMX@MWCNTs with the PCL/SF nanofibers were characterized. Then, the functional mesh was fabricated and fully evaluated in terms of antibacterial activity, mechanical properties and host response. Results: Our results demonstrated that the PCL/SF nanofibrous structure was fabricated successfully by electrospinning. After integrating with AMX@MWCNT by grafting and crosslinking, the functional mesh showed undeformed structure, modified surface hydrophilicity and biocompatible interfaces, abdominal wall-matched mechanical properties, and a sustained-release antibiotic profile in E. coli growth inhibition compared to those of PCL/SF mesh in vitro. In a rat model with subcutaneous implantation, the functional mesh incited less mesh-induced inflammatory and foreign body responses than PCL/SF mesh within 14 days. The histological analysis revealed less infiltration of granulocytes and macrophages during this period, resulting in the loosely packed collagen deposition on the functional mesh and prominent collagen incorporation. Discussion: Therefore, this designed PCL/SF-AMX@MWCNT nanofibrous mesh, functionalized with antibacterial and tissue-matched mechanical properties, provides a promising alternative for the repair of abdominal wall defects.


Assuntos
Amoxicilina/química , Antibacterianos/química , Nanofibras/química , Nanotecnologia/métodos , Telas Cirúrgicas , Amoxicilina/farmacocinética , Amoxicilina/farmacologia , Animais , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Colágeno/química , Colágeno/metabolismo , Reagentes para Ligações Cruzadas/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Fibroínas/química , Inflamação/etiologia , Masculino , Teste de Materiais , Camundongos , Nanotubos de Carbono/química , Poliésteres/química , Ratos Sprague-Dawley , Telas Cirúrgicas/efeitos adversos
16.
Int J Nanomedicine ; 15: 5473-5489, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32801701

RESUMO

Introduction: Biofilms protect bacteria from antibiotics and this can produce drug-resistant strains, especially the main pathogen of periodontitis, Porphyromonas gingivalis. Carbon quantum dots with various biomedical properties are considered to have great application potential in antibacterial and anti-biofilm treatment. Methods: Tinidazole carbon quantum dots (TCDs) and metronidazole carbon quantum dots (MCDs) were prepared by a hydrothermal method with the clinical antibacterial drugs tinidazole and metronidazole, respectively. Then, TCDs and MCDs were characterized by transmission electron microscopy, UV-visible spectroscopy, infrared spectroscopy and energy-dispersive spectrometry. The antibacterial effects were also investigated under different conditions. Results: The TCDs and MCDs had uniform sizes. The results of UV-visible and energy-dispersive spectrometry confirmed their important carbon polymerization structures and the activity of the nitro group, which had an evident inhibitory effect on P. gingivalis, but almost no effect on other bacteria, including Escherichia coli, Staphylococcus aureus and Prevotella nigrescens. Importantly, the TCDs could penetrate the biofilms to further effectively inhibit the growth of P. gingivalis under the biofilms. Furthermore, it was found that the antibacterial effect of TCDs lies in its ability to impair toxicity by inhibiting the major virulence factors and related genes involved in the biofilm formation of P. gingivalis, thus affecting the self-assembly of biofilm-related proteins. Conclusion: The findings demonstrate a promising new method for improving the efficiency of periodontitis treatment by penetrating the P. gingivalis biofilm with preparations of nano-level antibacterial drugs.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Porphyromonas gingivalis/efeitos dos fármacos , Pontos Quânticos/química , Animais , Antibacterianos/efeitos adversos , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Carbono/química , Carbono/farmacologia , Escherichia coli/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Humanos , Metronidazol/química , Metronidazol/farmacologia , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Transmissão , Periodontite/microbiologia , Porphyromonas gingivalis/genética , Porphyromonas gingivalis/fisiologia , Coelhos , Espectrofotometria Ultravioleta , Staphylococcus aureus/efeitos dos fármacos , Tinidazol/química , Tinidazol/farmacologia , Fatores de Virulência/antagonistas & inibidores
17.
Nat Commun ; 11(1): 3888, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32753666

RESUMO

First proposed as antimicrobial agents, histones were later recognized for their role in condensing chromosomes. Histone antimicrobial activity has been reported in innate immune responses. However, how histones kill bacteria has remained elusive. The co-localization of histones with antimicrobial peptides (AMPs) in immune cells suggests that histones may be part of a larger antimicrobial mechanism in vivo. Here we report that histone H2A enters E. coli and S. aureus through membrane pores formed by the AMPs LL-37 and magainin-2. H2A enhances AMP-induced pores, depolarizes the bacterial membrane potential, and impairs membrane recovery. Inside the cytoplasm, H2A reorganizes bacterial chromosomal DNA and inhibits global transcription. Whereas bacteria recover from the pore-forming effects of LL-37, the concomitant effects of H2A and LL-37 are irrecoverable. Their combination constitutes a positive feedback loop that exponentially amplifies their antimicrobial activities, causing antimicrobial synergy. More generally, treatment with H2A and the pore-forming antibiotic polymyxin B completely eradicates bacterial growth.


Assuntos
Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/genética , Estruturas Cromossômicas/efeitos dos fármacos , Histonas/metabolismo , Prótons , Animais , Estruturas Cromossômicas/metabolismo , Cromossomos Bacterianos/metabolismo , DNA Bacteriano/metabolismo , Sinergismo Farmacológico , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Imunidade Inata , Mamíferos , Polimixina B/farmacologia , Análise de Sequência de RNA , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/metabolismo
18.
Nat Commun ; 11(1): 4013, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32782250

RESUMO

Antibiotics that interfere with translation, when combined, interact in diverse and difficult-to-predict ways. Here, we explain these interactions by "translation bottlenecks": points in the translation cycle where antibiotics block ribosomal progression. To elucidate the underlying mechanisms of drug interactions between translation inhibitors, we generate translation bottlenecks genetically using inducible control of translation factors that regulate well-defined translation cycle steps. These perturbations accurately mimic antibiotic action and drug interactions, supporting that the interplay of different translation bottlenecks causes these interactions. We further show that growth laws, combined with drug uptake and binding kinetics, enable the direct prediction of a large fraction of observed interactions, yet fail to predict suppression. However, varying two translation bottlenecks simultaneously supports that dense traffic of ribosomes and competition for translation factors account for the previously unexplained suppression. These results highlight the importance of "continuous epistasis" in bacterial physiology.


Assuntos
Antibacterianos/farmacologia , Modelos Teóricos , Biossíntese de Proteínas/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Interações Medicamentosas , Epistasia Genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Biossíntese de Proteínas/fisiologia , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , Ribossomos/efeitos dos fármacos , Ribossomos/metabolismo
19.
PLoS One ; 15(7): e0235740, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32678859

RESUMO

This study evaluated the larvicidal activity of Origanum majorana Linnaeus essential oil, identified the chemical composition, evaluated the antimicrobial, cytotoxic and antioxidant potential. The larvicidal activity was evaluated against larvae of the third stage of Aedes aegypti Linaeus, whereas the chemical composition was identified by gas chromatography coupled to mass spectrometer, the antimicrobial activity was carried out against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus auereus, the antioxidant activity was evaluated from of 2.2-diphenyl-1-picryl-hydrazila sequestration and Artemia salina Leach cytotoxicity. Regarding to the results, the larvicidal activity showed that O. majorana L. essential oil caused high mortality in A. aegypti L. larvae. In the chromatographic analysis, the main component found in O. majorana L. essential oil was pulegone (57.05%), followed by the other components verbenone (16.92%), trans-p-menthan-2-one (8.57%), iso-menthone (5.58%), piperitone (2.83%), 3-octanol (2.35%) and isopulegol (1.47%). The antimicrobial activity showed that E. coli and P. aeruginosa bacteria were more sensitive to oil than S. aureus, which was resistant at all concentrations. Essential oil did not present antioxidant activity, but it has high cytotoxic activity against A. salina L.


Assuntos
Aedes/efeitos dos fármacos , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Óleos Voláteis/farmacologia , Origanum/química , Animais , Antibacterianos/química , Antioxidantes/farmacologia , Bactérias/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Folhas de Planta/química , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
20.
Int J Nanomedicine ; 15: 4275-4288, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32606677

RESUMO

Purpose: Selenium nanoparticles (Se NPs) are promising antibacterial agents to tackle the growing problem of antimicrobial resistance. The aim of this study was to fabricate Se NPs with a net positive charge to enhance their antibacterial efficacy. Methods: Se NPs were coated with a positively charged protein - recombinant spider silk protein eADF4(κ16) - to give them a net positive surface charge. Their cytotoxicity and antibacterial activity were investigated, with negatively charged polyvinyl alcohol coated Se NPs as a control. Besides, these eADF4(κ16)-coated Se NPs were immobilized on the spider silk films, and the antibacterial activity of these films was investigated. Results: Compared to the negatively charged polyvinyl alcohol coated Se NPs, the positively charged eADF4(κ16)-coated Se NPs demonstrated a much higher bactericidal efficacy against the Gram-negative bacteria E. coli, with a minimum bactericidal concentration (MBC) approximately 50 times lower than that of negatively charged Se NPs. Cytotoxicity testing showed that the eADF4(κ16)-coated Se NPs are safe to both Balb/3T3 mouse embryo fibroblasts and HaCaT human skin keratinocytes up to 31 µg/mL, which is much higher than the MBC of these particles against E. coli (8 ± 1 µg/mL). In addition, antibacterial coatings were created by immobilising the eADF4(κ16)-coated Se NPs on positively charged spider silk films and these were shown to retain good bactericidal efficacy and overcome the issue of low particle stability in culture broth. It was found that these Se NPs needed to be released from the film surface in order to exert their antibacterial effects and this release can be regulated by the surface charge of the film, such as the change of the spider silk protein used. Conclusion: Overall, eADF4(κ16)-coated Se NPs are promising new antibacterial agents against life-threatening bacteria.


Assuntos
Antibacterianos/farmacologia , Nanopartículas/química , Proteínas Recombinantes/farmacologia , Selênio/farmacologia , Seda/farmacologia , Células 3T3 , Animais , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Contagem de Colônia Microbiana , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Humanos , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Nanopartículas/ultraestrutura , Tamanho da Partícula
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