RESUMO
The increase in the use of antimicrobials such as colistin for the treatment of infectious diseases has led to the appearance of Aeromonas strains resistant to this drug. However, resistance to colistin not only occurs in the clinical area but has also been determined in Aeromonas isolates from the environment or animals, which has been determined by the detection of mcr genes that confer a resistance mechanism to colistin. The variants mcr-1, mcr-3, and mcr-5 have been detected in the genus Aeromonas in animal, environmental, and human fluids samples. In this article, an overview of the resistance to colistin in Aeromonas is shown, as well as the generalities of this molecule and the recommended methods to determine colistin resistance to be used in some of the genus Aeromonas.
Assuntos
Aeromonas/genética , Antibacterianos/química , Colistina/química , Farmacorresistência Bacteriana/genética , Aeromonas/efeitos dos fármacos , Aeromonas/patogenicidade , Antibacterianos/uso terapêutico , Proteínas de Bactérias/genética , Colistina/uso terapêutico , Humanos , Plasmídeos/efeitos dos fármacos , Plasmídeos/genéticaRESUMO
CMY-type ß-lactamases are the most reported plasmid-mediated AmpC (pAmpC), with the CMY-2-like group being the most clinically relevant described in Escherichia coli at human-animal-environment interface. Shiga toxin-producing E. coli (STEC) lineages are zoonotic pathogens commonly reported causing serious clinical conditions in humans, including severe diarrheagenic diseases. Therefore, this study aimed to investigate a multidrug-resistant (MDR) STEC isolate (A313) recovered from a healthy sheep and carrying mobile blaCMY-97, that encodes a pAmpC belonging to the CMY-2-like group. The A313 isolate exhibited a MDR profile to clinically relevant antimicrobials (i.e., cephalosporins, aminoglycosides, and fluoroquinolones), but reduced susceptibility to extended-spectrum cephalosporins and aztreonam. Besides, virulence genes (stx2, gad and iutA) were detected in A313, which belonged to ST215/CC10 and phylogenetic group A, whereas the fimH54 was identified. The blaCMY-97 gene and other antimicrobial resistance determinants [aph(6)-Id, aph(3â³)-Ib, aac(3)-IId, aadA5, floR, tetA, sul1, and sul2], as well as genes encoding tolerance to mercury (merRTPCADE), were harbored by an IncC plasmid (named pA313-CMY-97, ~ 176 kb). A novel genetic context of blaCMY-2-like, in which a 208-bp ISEcp1 was truncated by an IS26 in the opposite orientation upstream of the blaCMY-97 gene (IS26-∆ISEcp1-blaCMY-97-blc-sugE-encR), was also identified in pA313-CMY-97. To the best of our knowledge, this is the first report on the acquisition of blaCMY-97 into a plasmid. Therefore, we reported ovine as reservoir of clinically relevant MDR bacteria carrying mobile blaCMY-97 with potential for zoonotic transmission.
Assuntos
Farmacorresistência Bacteriana Múltipla/genética , Infecções por Escherichia coli/veterinária , Plasmídeos/genética , Doenças dos Ovinos/microbiologia , Escherichia coli Shiga Toxigênica/genética , Animais , Infecções por Escherichia coli/microbiologia , Plasmídeos/efeitos dos fármacos , Ovinos , Carneiro Doméstico , Escherichia coli Shiga Toxigênica/efeitos dos fármacosRESUMO
OBJECTIVE: To describe the clinical features, outcomes, and molecular epidemiology of an outbreak of multidrug resistant (MDR) A. baumannii. METHODS: We performed a retrospective analysis of all MDR A. baumannii isolates recovered during an outbreak from 2011 to 2015 in a tertiary care cancer hospital. Cases were classified as colonized or infected. We determined sequence types following the Bartual scheme and plasmid profiles. RESULTS: There were 106 strains of A. baumannii isolated during the study period. Sixty-six (62.3%) were considered as infection and 40 (37.7%) as colonization. The index case, identified by molecular epidemiology, was a patient with a drain transferred from a hospital outside Mexico City. Ninety-eight additional cases had the same MultiLocus Sequence Typing (MLST) 758, of which 94 also had the same plasmid profile, two had an extra plasmid, and two had a different plasmid. The remaining seven isolates belonged to different MLSTs. Fifty-three patients (50%) died within 30 days of A. baumanniii isolation: 28 (20%) in colonized and 45 (68.2%) in those classified as infection (p<0.001). In multivariate regression analysis, clinical infection and patients with hematologic neoplasm, predicted 30-day mortality. The molecular epidemiology of this outbreak showed the threat posed by the introduction of MDR strains from other institutions in a hospital of immunosuppressed patients and highlights the importance of adhering to preventive measures, including contact isolation, when admitting patients with draining wounds who have been hospitalized in other institutions.
Assuntos
Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/mortalidade , Infecção Hospitalar/epidemiologia , Acinetobacter baumannii/genética , Acinetobacter baumannii/isolamento & purificação , Acinetobacter baumannii/patogenicidade , Adulto , Idoso , Estudos de Casos e Controles , Surtos de Doenças , Resistência a Múltiplos Medicamentos/fisiologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Farmacorresistência Bacteriana Múltipla/genética , Feminino , Hospitais Gerais , Humanos , Masculino , México , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Epidemiologia Molecular/métodos , Tipagem de Sequências Multilocus/métodos , Plasmídeos/efeitos dos fármacos , Plasmídeos/genética , Estudos Retrospectivos , Análise de Sequência de DNA/métodos , beta-Lactamases/genéticaRESUMO
OBJECTIVES: Earlier studies have demonstrated the use of inactivated recombinant E. coli (bacterins), to protect against Clostridium spp. in vaccinated animals. These bacterins have a simpler, safer, and faster production process. However, these bacterins carry expression plasmids, containing antibiotic resistance gene, which could be assimilate accidentally by environmental microorganisms. Considering this, we aimed to impair this plasmids using formaldehyde at different concentrations. RESULTS: This compound inactivated the highest density of cells in 24 h. KanR cassette amplification was found to be impaired with 0.8% for 24 h or 0.4% for 72 h. Upon electroporation, E. coli DH5α ultracompetent cells were unable to acquire the plasmids extracted from the bacterins after inactivation procedure. Formaldehyde-treated bacterins were incubated with other viable strains of E. coli, leading to no detectable gene transfer. CONCLUSIONS: We found that this compound is effective as an inactivation agent. Here we demonstrate the biosafety involving antibiotic resistance gene of recombinant E. coli vaccines allowing to industrial production and animal application.
Assuntos
Escherichia coli/genética , Formaldeído/farmacologia , Resistência a Canamicina/efeitos dos fármacos , Plasmídeos/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Vacinas contra Escherichia coli/efeitos adversos , Vacinas contra Escherichia coli/genética , Transferência Genética Horizontal/efeitos dos fármacos , Plasmídeos/genética , Vacinas de Produtos Inativados , Vacinas SintéticasRESUMO
Staphylococcus nepalensis is a commensal bacterium from the oral microbiota of domestic cats, with a still obscure clinical importance. In this work, we analysed the ability of feline strains of S. nepalensis to transfer antimicrobial resistance genes to Staphylococcus aureus isolated from humans through plasmids. To this end, we first analysed all publicly available genomes from cat staphylococci using computational methods to build a pan-resistome. Genes that encode resistance to erythromycin, gentamicin, mupirocin and tetracycline, common to human and cat staphylococci and previously described to be located in mobile genetic elements, were chosen for the next analyses. We studied 15 strains of S. nepalensis, which were shown to be genetically different by GTG5-PCR. As observed by disc diffusion, resistance to tetracycline was widespread (80â%), followed by resistance to erythromycin (40â%), gentamicin (27â%) and mupirocin (7â%). The strains were positive for several antimicrobial resistance genes and more than half of them harboured plasmids. The loss of plasmids and resistance genes in some strains were induced by stress with SDS. Through conjugation experiments, we observed that these plasmids can be transferred to S. aureus, thus increasing its potential to resist drug therapy. Our findings show that S. nepalensis, an underestimated inhabitant of the cat microbiota, can be a reservoir of antimicrobial resistance genes for S. aureus and, like many other staphylococci, be an overlooked and silent threat to their animal hosts and humans living with them.
Assuntos
Reservatórios de Doenças/veterinária , Farmacorresistência Bacteriana/genética , Transferência Genética Horizontal , Staphylococcus/fisiologia , Animais , Animais Domésticos , Antibacterianos/farmacologia , Gatos , Reservatórios de Doenças/microbiologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Genes Bacterianos , Variação Genética , Testes de Sensibilidade Microbiana , Plasmídeos/efeitos dos fármacos , Plasmídeos/genética , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/veterinária , Staphylococcus/efeitos dos fármacos , Staphylococcus/genética , Staphylococcus/isolamento & purificação , Staphylococcus aureus/genéticaRESUMO
The use of pesticides has been increasing due to the great agricultural production worldwide. The pesticides are used to eradicate pests and weeds; however, these compounds are classified as toxic to non-target organisms. Atrazine and diuron are herbicides widely used to control grassy and broadleaf weeds and weed control in agricultural crops and non-crop areas. Heavy metals are also important environmental contaminants that affect the ecological system. This study aimed to investigate the presence of herbicides-degrading genes and heavy metal resistance genes in bacterial isolates from two different soil samples from two Brazilian regions and to determine the genetic location of these genes. In this study, two isolates were obtained and identified as Escherichia fergusonii and Bacillus sp. Both isolates presented atzA, atzB, atzC, atzD, atzE, atzF, puhA, and copA genes and two plasmids each, being the major with ~ 60 Kb and a smaller with ~ 3.2 Kb. Both isolates presented the atzA-F genes inside the larger plasmid, while the puhA and copA genes were detected in the smaller plasmid. Digestion reactions were performed and showed that the ~ 60-Kb plasmid presented the same restriction profile using different restriction enzymes, suggesting that this plasmid harboring the complete degradation pathway to atrazine was found in both isolates. These results suggest the dispersion of these plasmids and the multi-herbicide degradation potential in both isolates to atrazine and diuron, which are widely used in different culture types worldwide.
Assuntos
Atrazina/metabolismo , Bacillus/genética , Bacillus/metabolismo , Diurona/metabolismo , Escherichia/genética , Escherichia/metabolismo , Herbicidas/metabolismo , Metais Pesados/toxicidade , Plasmídeos/genética , Bacillus/isolamento & purificação , Biodegradação Ambiental , Brasil , Farmacorresistência Bacteriana/genética , Monitoramento Ambiental , Escherichia/isolamento & purificação , Plasmídeos/efeitos dos fármacos , Microbiologia do SoloRESUMO
Due to their antimicrobial properties, copper nanoparticles (CuNPs) have been proposed to be used in agriculture for pest control. Pesticides removal is mainly done by microorganisms, whose genes usually are found in conjugative catabolic plasmids (CCP). The aim of this work was to evaluate if CuNPs at subinhibitory concentrations modify the conjugation frequency (CF) of two CCP (pJP4 and pADP1). CuNPs were characterized by scanning electron microscopy with an X-ray detector, dynamic light scattering and X-ray diffraction. Mating assays were done in LB broth supplemented with CuNPs (10, 20, 50 and 100⯵gâ¯mL-1) or equivalent concentrations of CuSO4. Interestingly, we observed that in LB, Cu+2 release from CuNPs is fast as evaluated by atomic absorption spectrophotometry. Donor and recipient strains were able to grow in all copper concentrations assayed, but CF of mating pairs was reduced to 10% in the presence of copper at 20 or 50⯵g Cu mL-1 compared to control. Thus, our results indicated that both copper forms, CuNPs or CuSO4, negatively affected the transfer of catabolic plasmids by conjugation. Since dissemination of degradative genes by conjugation contribute to degradation of pesticides by microorganisms, this work improves our understanding of the risks of using copper in agriculture soils, which could affect the biodegradative potential of microbial communities.
Assuntos
Anti-Infecciosos/toxicidade , Conjugação Genética/efeitos dos fármacos , Cobre/toxicidade , Nanopartículas Metálicas/toxicidade , Microbiota/efeitos dos fármacos , Plasmídeos/efeitos dos fármacos , Microbiologia do Solo , Biodegradação Ambiental , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Microbiota/genética , Microscopia Eletrônica de Varredura , Microbiologia do Solo/normas , Difração de Raios XRESUMO
OBJECTIVE: We describe an IncX4 pHC891/16mcr plasmid carrying mcr-1 in a colistin-resistant and carbapenem-susceptible E. coli isolate (HC891/16), ST156, which caused a blood infection in a Brazilian patient with gallbladder adenocarcinoma. METHODS: Strain HC891/16 was subjected to whole genome sequencing using the MiSeq Platform (Illumina, Inc., USA). Assembly was performed using Mira and ABACAS. RESULTS: The isolates showed resistance only to ciprofloxacin, ampicillin and cefoxitin, and whole-genome sequencing revealed the presence of aac(6')Ib-cr and blaTEM1. CONCLUSION: Our findings warn of the possible silent dissemination of colistin resistance by carbapenem-susceptible mcr-1 producers, as colistin susceptibility is commonly tested only among carbapenem-resistant isolates.
Assuntos
Antibacterianos/farmacologia , Bacteriemia/tratamento farmacológico , Carbapenêmicos/farmacologia , Colistina/farmacologia , Proteínas de Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Idoso , Brasil , Farmacorresistência Bacteriana Múltipla , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/tratamento farmacológico , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/isolamento & purificação , Feminino , Humanos , Testes de Sensibilidade Microbiana , Plasmídeos/efeitos dos fármacosRESUMO
OBJECTIVE: We describe an IncX4 pHC891/16mcr plasmid carrying mcr-1 in a colistin-resistant and carbapenem-susceptible E. coli isolate (HC891/16), ST156, which caused a blood infection in a Brazilian patient with gallbladder adenocarcinoma. METHODS: Strain HC891/16 was subjected to whole genome sequencing using the MiSeq Platform (Illumina, Inc., USA). Assembly was performed using Mira and ABACAS. RESULTS: The isolates showed resistance only to ciprofloxacin, ampicillin and cefoxitin, and whole-genome sequencing revealed the presence of aac(6')Ib-cr and blaTEM1. CONCLUSION: Our findings warn of the possible silent dissemination of colistin resistance by carbapenem-susceptible mcr-1 producers, as colistin susceptibility is commonly tested only among carbapenem-resistant isolates.
Assuntos
Humanos , Feminino , Idoso , Carbapenêmicos/farmacologia , Bacteriemia/tratamento farmacológico , Colistina/farmacologia , Proteínas de Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Antibacterianos/farmacologia , Plasmídeos/efeitos dos fármacos , Brasil , Testes de Sensibilidade Microbiana , Proteínas de Escherichia coli/isolamento & purificação , Proteínas de Escherichia coli/genética , Farmacorresistência Bacteriana Múltipla , Escherichia coli/isolamento & purificação , Escherichia coli/genética , Infecções por Escherichia coli/tratamento farmacológicoRESUMO
A molecular survey was conducted in Cochabamba, Bolivia, to characterize the mechanism involved in the resistance to clinically relevant antibiotics. Extended Spectrum β-lactamase encoding genes and plasmid-mediated quinolone resistance (PMQR) markers were investigated in a total of 101 oxyimino-cephalosporin-resistant enterobacteria recovered from different health centers during four months (2012-2013). CTX-M enzymes were detected in all isolates, being the CTX-M-1 group the most prevalent (88.1%). The presence of blaOXA-1 was detected in 76.4% of these isolates. A high quinolone resistance rate was observed among the included isolates. The aac(6′)-Ib-cr gene was the most frequent PMQR identified (83.0%). Furthermore, 6 isolates harbored the qnrB gene. Interestingly, qepA1 (6) and oqxAB (1), were detected in 7 Escherichia coli, being the latter the first to be reported in Bolivia. This study constitutes the first molecular survey on resistance markers in clinical enterobacterial isolates in Cochabamba, Bolivia, contributing to the regional knowledge of the epidemiological situation. The molecular epidemiology observed herein resembles the scene reported in South America.
Se llevó a cabo un relevamiento molecular de la resistencia a antibióticos de importancia clínica en aislamientos recuperados en Cochabamba, Bolivia. Se estudiaron los genes codificantes de β-lactamasas de espectro extendido y de resistencia a quinolonas de localización plasmídica (PMQR) en un total de 101 aislamientos de enterobacterias resistentes a oximinocefalosporinas recuperados en distintos centros de salud, durante 4 meses (2012-2013). En todos ellos se detectó la presencia de cefotaximasas, las CTX-M grupo 1 fueron las más prevalentes (88,1%). La presencia de blaOXA-1 se detectó en el 76,4% de estos aislamientos. Se observó una elevada proporción de aislamientos resistentes a quinolonas. El gen aac(6′)-Ib-cr fue el determinante PMQR más frecuentemente identificado (83%). Además, 6 aislamientos resultaron ser portadores de qnrB. Por otro lado, cabe remarcar que 7 Escherichia coli presentaron qepA1 (6) y oqxAB (1); se documenta así por primera vez la presencia de oqxAB en Bolivia. Este estudio constituye el primer relevamiento de marcadores de resistencia en aislamientos clínicos de enterobacterias en Cochabamba, Bolivia; de este modo se contribuye al conocimiento regional de la situación epidemiológica, la cual presenta un escenario similar al observado en el resto de Latinoamérica.
Assuntos
Plasmídeos/efeitos dos fármacos , beta-Lactamases/efeitos dos fármacos , Resistência Microbiana a Medicamentos , Quinolonas/farmacologia , Enterobacteriaceae/isolamento & purificação , Bolívia/epidemiologia , Enterobacteriaceae/efeitos dos fármacosRESUMO
Wastewater treatment plants (WWTPs) harbor bacteria and antimicrobial resistance genes, favoring gene exchange events and resistance dissemination. Here, a culture-based and metagenomic survey of qnrA, qnrB, qnrS, and aac(6')-Ib genes from raw sewage (RS) and activated sludge (AS) of a full-scale municipal WWTP was performed. A total of 96 bacterial isolates were recovered from nalidixic acid-enrichment cultures. Bacteria harboring the aac(6')-Ib gene predominated in RS, whereas qnrS-positive isolates were specific to AS. Novel qnrS- and aac(6')-Ib-cr positive species were identified: Morganella morganii, Providencia rettgeri, and Pseudomonas guangdongensis (qnrS), and Alcaligenes faecalis and P. rettgeri (aac(6')-Ib-cr). Analysis of qnrS and aac(6')-Ib sequences from isolates and clone libraries suggested that the diversity of qnrS is wider than that of aac(6')-Ib. A large number of amino acid mutations were observed in the QnrS and AAC(6')-Ib proteins at previously undetected positions, whose structural implications are not clear. An accumulation of mutations at the C72, Q73, L74, A75 and M76 positions of QnrS, and D181 of AAC(6')-Ib might be important for resistance. These findings add significant information on bacteria harboring qnrS and aac(6')-Ib genes, and the presence of novel mutations that may eventually emerge in clinical isolates.
Assuntos
Escherichia coli/isolamento & purificação , Esgotos , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Fluoroquinolonas , Testes de Sensibilidade Microbiana , Mutação , Plasmídeos/efeitos dos fármacos , QuinolonasRESUMO
A colistin-resistant Escherichia coli strain was recovered from a patient with a diabetic foot infection in Brazil. Whole-genome analysis revealed that the E. coli isolate belonged to the widespread sequence type (ST) 101 and harbored the mcr-1 gene on an IncX4 plasmid that was highly similar to mcr-1-bearing IncX4 plasmids that were recently identified in Enterobacteriaceae from food, animal, and human samples recovered on different continents. These results suggest that self-transmissible IncX4-type plasmids may represent promiscuous plasmids contributing to the intercontinental spread of the mcr-1 gene.
Assuntos
Colistina/farmacologia , Farmacorresistência Bacteriana/genética , Proteínas de Escherichia coli/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Idoso , Brasil , Farmacorresistência Bacteriana/efeitos dos fármacos , Escherichia coli/genética , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/microbiologia , Humanos , Masculino , Testes de Sensibilidade Microbiana , Plasmídeos/efeitos dos fármacos , Plasmídeos/genéticaRESUMO
The ubiquitin-proteasome system (UPS) is a specific, non-lysosomal pathway responsible for the controlled degradation of abnormal and short-half-life proteins. Despite its relevance in cell homeostasis, information regarding control of the UPS component gene expression is lacking. Data from a recent study suggest that the aryl hydrocarbon receptor (AHR), a ligand-dependent transcription factor, might control the expression of several genes encoding for UPS proteins. Here, we showed that activation of AHR by TCDD and ß-naphthoflavone (ß-NF) results in Ubcm4 gene induction accompanied by an increase in protein levels. UbcM4 is an ubiquitin-conjugating enzyme or E2 protein that in association with ubiquitin ligase enzymes or E3 ligases promotes the ubiquitination and 26S proteasome-mediated degradation of different proteins, including p53, c-Myc, and c-Fos. We also present data demonstrating increased c-Fos ubiquitination and proteasomal degradation through the AHR-mediated induction of UbcM4 expression. The present study shows that AHR modulates the degradation of proteins involved in cell cycle control, consistent with previous reports demonstrating an essential role of the AHR in cell cycle regulation.
Assuntos
Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fos/metabolismo , Receptores de Hidrocarboneto Arílico/efeitos dos fármacos , Enzimas de Conjugação de Ubiquitina/biossíntese , Ubiquitinação/efeitos dos fármacos , Linhagem Celular , Expressão Gênica/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Humanos , Plasmídeos/efeitos dos fármacos , Dibenzodioxinas Policloradas/farmacologia , Proteínas Proto-Oncogênicas c-fos/efeitos dos fármacos , Transfecção , Enzimas de Conjugação de Ubiquitina/efeitos dos fármacos , Enzimas de Conjugação de Ubiquitina/genética , beta-Naftoflavona/farmacologiaRESUMO
Antibiotic resistance, especially due to ß-lactamases, has become one of the main obstacles in the correct treatment of Salmonella infections; furthermore, antibiotic resistance determines a gain of function that may encompass a biological cost, or fitness reduction, to the resistant bacteria. The aim of this work was to determine in vitro if the production of the class B ß-lactamase VIM-2 determined a fitness cost for Salmonella enterica serovar Typhimurium. To that end the gene blaVIM-2 was cloned into the virulent strain S. Typhimurium SL1344, using both the tightly regulated pBAD22 vector and the natural plasmid pST12, for inducible and constitutive expression, respectively. Fitness studies were performed by means of motility, growth rate, invasiveness in epithelial cells, and plasmid stability. The expression of blaVIM-2 was accompanied by alterations in micro- and macroscopic morphology and reduced growth rate and motility, as well as diminished invasiveness in epithelial cells. These results suggest that VIM-2 production entails a substantial fitness cost for S. Typhimurium, which in turn may account for the extremely low number of reports of metallo-ß-lactamase-producing Salmonella spp.
Assuntos
Farmacorresistência Bacteriana Múltipla/genética , Aptidão Genética/genética , Infecções por Salmonella/tratamento farmacológico , Salmonella typhimurium/patogenicidade , beta-Lactamases/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Células CACO-2 , Linhagem Celular , Clonagem Molecular , Células Epiteliais/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Plasmídeos/efeitos dos fármacos , Plasmídeos/genética , Infecções por Salmonella/microbiologia , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , beta-Lactamases/biossínteseRESUMO
Aquatic environments often receive wastewater containing pollutants such as antibiotics and heavy metals from hospital sewage, as well as contaminants from soil. The presence of these pollutants can increase the rate of exchange of resistant genes between environmental and pathogenic bacteria, which can make the treatment of various types of bacterial infections in humans and animals difficult, in addition to causing environmental problems such as ecological risk. In this study, two tetracycline-resistant Pseudomonas aeruginosa (EW32 and EW33), isolated from aquatic environments close to industries and a hospital in southeastern Brazil, were investigated regarding the possible association between tetracycline and heavy metal resistance. The isolate EW32 presented a conjugative plasmid with coresistance to tetracycline and copper, reinforcing the concern that antibiotic resistance by acquisition of plasmids can be induced by the selective pressure of heavy metals in the environment.
Assuntos
Antibacterianos/análise , Metais Pesados/análise , Poluentes Químicos da Água/análise , Antibacterianos/toxicidade , Brasil , Farmacorresistência Bacteriana/genética , Humanos , Metais Pesados/toxicidade , Plasmídeos/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/isolamento & purificação , Medição de Risco , Esgotos/química , Esgotos/microbiologia , Águas Residuárias/química , Poluentes Químicos da Água/toxicidadeRESUMO
Pharmacological doses of ascorbate were evaluated for its ability to potentiate the toxicity of sodium orthovanadate (Na(3)VO(4)) in tumor cells. Cytotoxicity, inhibition of cell proliferation, generation of ROS and DNA fragmentation were assessed in T24 cells. Na(3)VO(4) was cytotoxic against T24 cells (EC(50)=5.8 µM at 24 h), but in the presence of ascorbate (100 µM) the EC(50) fell to 3.3 µM. Na(3)VO(4) plus ascorbate caused a strong inhibition of cell proliferation (up to 20%) and increased the generation of ROS (4-fold). Na(3)VO(4) did not directly cleave plasmid DNA, at this aspect no synergism was found occurring between Na(3)VO(4) and ascorbate once the resulting action of the combination was no greater than that of both substances administered separately. Cells from Ehrlich ascites carcinoma-bearing mice were used to determine the activity of antioxidant enzymes, the extent of the oxidative damage and the type of cell death. Na(3)VO(4) alone, or combined with ascorbate, increased catalase activity, but only Na(3)VO(4) plus ascorbate increased superoxide dismutase activity (up to 4-fold). Oxidative damage on proteins and lipids was higher due to the treatment done with Na(3)VO(4) plus ascorbate (2-3-fold). Ascorbate potentiated apoptosis in tumor cells from mice treated with Na(3)VO(4). The results indicate that pharmacological doses of ascorbate enhance the generation of ROS induced by Na(3)VO(4) in tumor cells causing inhibition of proliferation and apoptosis. Apoptosis induced by orthovanadate and ascorbate is closer related to inhibition on Bcl-xL and activation of Bax. Our data apparently rule out a mechanism of cell demise p53-dependent or related to Cdk2 impairment.
Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Ácido Ascórbico/farmacologia , Proliferação de Células/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Vanadatos/farmacologia , Animais , Linhagem Celular Tumoral , DNA/efeitos dos fármacos , Fragmentação do DNA , Sinergismo Farmacológico , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Plasmídeos/efeitos dos fármacos , Proteína X Associada a bcl-2/agonistas , Proteína bcl-X/antagonistas & inibidoresRESUMO
Coutarea hexandra is a species commonly known in Brazil as quina, and its bark is used in folk medicine. In this study, we assess the mutagenic and DNA-damaging effects of ethanol extracts from C. hexandra stem bark (SCH) and leaves (LCH) by employing the Ames test on the TA98 and TA100 strains of Salmonella typhimurium in addition to a plasmid treatment test. Furthermore, we performed a phytochemical analysis by TLC and HPLC, a quantification of the phenolic constituents and an assessment of the antioxidative activity. SCH and LCH showed mutagenic action in the Ames test for TA98 strains after metabolic activation. LCH also showed mutagenicity for the TA100 strain after metabolic activation. The findings from the plasmid treatment test did not indicate any DNA-damaging activity for either of the extracts with the tested dosages. SCH showed greater flavonoid content and greater antioxidative potential in relation to LCH. This study suggests that caution is advisable in the use of this plant. However, in vivo studies should be conducted to confirm these data.
Assuntos
Antioxidantes/toxicidade , Dano ao DNA , Mutagênicos/toxicidade , Extratos Vegetais/toxicidade , Plasmídeos/efeitos dos fármacos , Rubiaceae , Salmonella typhimurium/efeitos dos fármacos , Antioxidantes/química , Antioxidantes/isolamento & purificação , Compostos de Bifenilo/química , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Etanol/química , Flavonoides/análise , Flavonoides/toxicidade , Testes de Mutagenicidade , Mutagênicos/química , Mutagênicos/isolamento & purificação , Picratos/química , Casca de Planta , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Folhas de Planta , Plantas Medicinais , Proantocianidinas/análise , Proantocianidinas/toxicidade , Medição de Risco , Rubiaceae/química , Salmonella typhimurium/genética , Solventes/químicaRESUMO
When mosses are exposed to increased quantities of ultraviolet (UV) radiation, they produce more secondary metabolites. Antarctica moss Sanionia uncinata (Hedw.) Loeske has presented high carotenoid contents in response to an increase in UVB radiation. This moss has been recommended as a potential source of antioxidants. In the present work, the protective and enhancing effects of aqueous (AE) and hydroalcoholic (HE) extracts of S. uncinata on the cleavage of supercoiled DNA were evaluated through topological modifications, quantified by densitometry after agarose gel electrophoresis. Total phenolic contents reached 5.89 mg/g. Our data demonstrated that the extract does not induce DNA cleavage. Furthermore, both extracts showed antioxidant activity that protected the DNA against cleavage induced by (i) O(2)(â¢-), 89% (AE) and 94% (HE) (P<0.05), and (ii) (.)OH, 17% (AE) and 18% (HE). However, the extracts intensified cleavage induced by Fenton-like reactions: (i) Cu(2+)/H(2)O(2), 94% (AE) and 100% (HE) (P<0.05), and (ii) SnCl(2), 62% (AE) and 56% (HE). DNA damages seem to follow different ways: (i) in the presence of Fenton-like reactions could be via reactive oxygen species generation and (ii) with HE/Cu(2+) could have also been triggered by other mechanisms.
Assuntos
Antioxidantes/farmacologia , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Espécies Reativas de Oxigênio/metabolismo , Clivagem do DNA/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Plasmídeos/efeitos dos fármacos , Plasmídeos/genéticaRESUMO
A new complex of the oxovanadium(IV) cation with the flavolignan silibinin has been synthesized and characterized. Vanadium compounds show interesting biological and pharmacological properties and some of them display antitumoral actions. Flavonoids are part of a larger group of antioxidant compounds called polyphenols which may inhibit the proliferation and growth of cancer cells. The antioxidant and antitumoral effects of silibinin and its oxovanadium(IV) complex were investigated. Silibinin acted as a very strong antioxidant and its complexation with oxovanadium(IV) improved this behavior. Besides, the generation of reactive oxygen species (ROS) by this compound was favored in tumoral (UMR106) cells and correlated with the deleterious behavior in the proliferation of this cell line. Conversely, silibinin did not exert any effect on the proliferation of normal osteoblasts (MC3T3E1). The cytotoxic action and ROS generation of the oxovanadium(IV) complex was more effective in tumoral cells. This behavior was not consistent with cleaving DNA of plasmid DNA pA1 because no significant cleaving activity was observed in both cases. These results suggest that the main deleterious mechanisms may take place through cytotoxic effects more than genotoxic actions. A comparison with our own findings on the behavior of other flavonoids and their vanadyl(IV) complex has also been performed.
Assuntos
Antineoplásicos/farmacologia , Antioxidantes/farmacologia , Clivagem do DNA/efeitos dos fármacos , Compostos Organometálicos/farmacologia , Silimarina/farmacologia , Vanadatos/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Antioxidantes/síntese química , Antioxidantes/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Espectroscopia de Ressonância de Spin Eletrônica , Estrutura Molecular , Compostos Organometálicos/síntese química , Compostos Organometálicos/química , Plasmídeos/efeitos dos fármacos , Ratos , Espécies Reativas de Oxigênio/metabolismo , Silibina , Silimarina/química , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Relação Estrutura-Atividade , Vanadatos/químicaRESUMO
Refractory and relapsed leukemia is a major problem during cancer therapy, which is due to the aberrant activation of Wnt/β-catenin signaling pathway. Activation of this pathway is promoted by wingless (Wnt) proteins and induces co-activator β-catenin binding to lymphoid enhancer factor (LEF)/T-cell factor protein (TCF). To provide a convenient system for the screening of anti-Wnt/β-catenin agents, we designed a bi-functional pGL4-TOP reporter plasmid that contained 3X β-catenin/LEF/TCF binding sites and a selectable marker. After transfection and hygromycin B selection, HEK 293-TOP and Jurkat-TOP stable clones were established. The luciferase activity in the stable clone was enhanced by the recombinant Wnt-3A (rWnt-3A; 100-400 ng/mL) and GSK3β inhibitor (2’Z,3’E)-6-bromoindirubin-3’-oxime (BIO; 5 µM) but was inhibited by aspirin (5 mM). Using this reporter model, we found that norcantharidin (NCTD; 100 µM) reduced 80 percent of rWnt-3A-induced luciferase activity. Furthermore, 50 µM NCTD inhibited 38 percent of BIO-induced luciferase activity in Jurkat-TOP stable cells. Employing ³H-thymidine uptake assay and Western blot analysis, we confirmed that NCTD (50 µM) significantly inhibited proliferation of Jurkat cells by 64 percent, which are the dominant β-catenin signaling cells and decreased β-catenin protein in a concentration-dependent manner. Thus, we established a stable HEK 293-TOP clone and successfully used it to identify the Wnt/β-catenin signaling inhibitor NCTD.