Browsing by Author "Martins, Anabela"
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- Ação antimicrobiana de extratos fenólicos de cogumelos silvestres contra Neisseria gonorrhoeaePublication . Alves, Maria José; Marques, Azucena; Ferreira, Isabel C. F. R.; Martins, Anabela; Pintado, ManuelaInfeções pelo gonococo e por clamídia estão entre as doenças sexualmente transmissíveis mais comuns causadas por bactérias no mundo. Por outro lado, tem-se verificado um aumento de resistência da Neisseria gonorrhoeae aos diferentes antimicrobianos usados no mercado, sendo desta forma urgente a descoberta de novas soluções antimicrobianas no combate a esta infeção. Assim, o objetivo do presente trabalho foi avaliar a atividade antimicrobiana de extratos e respetivos compostos fenólicos puros de nove espécies de cogumelos silvestres, provenientes do Nordeste de Portugal, contra Neisseria gonorrhoeae obtida de exsudados da uretra no CHTMAD – Centro Hospitalar de Trás-os-Montes e Alto Douro. Para a determinação das concentrações mínimas inibitórias (CMI) de crescimento recorreu-se ao método da microdiluição e ao ensaio colorimétrico com cloreto de p-iodonitrotetrazólio (INT). De um modo geral, todos os extratos apresentaram atividade antimicrobiana sobre a Neisseria gonorrhoeae, e alguns compostos parecem apresentar boa atividade antimicrobiana para esta bactéria, tornando-se pertinente estudar o mecanismo de ação destes compostos na inibição da bactéria bem como a sua toxicidade celular no sentido de avaliar possíveis aplicações clínicas na terapêutica e mesmo na prevenção da gonorreia.
- Extratos de cogumelos silvestres potenciam a ação de antibióticos contra bactérias multi- resistentesPublication . Lourenço, Inês; Alves, Maria José; Martins, Anabela; Pintado, ManuelaO principal objetivo deste estudo foi avaliar a capacidade de extratos obtidos a partir de cogumelos silvestres (Russula delica, Leucopaxilus giganteus, Mycena rosea, Fistulina hepatica e Sarcodon imbricatum) potenciarem o efeito de antibióticos comumente utilizados, de forma a diminuir as doses terapêuticas utilizadas, contribuindo assim para a redução das resistências bacterianas. Os extratos de cogumelos foram testados em diferentes bactérias multirresistentes (Escherichia coli, Escherichia coli produtora de β-lactamases e Satphylococcus aureus resistentes à meticilina (MRSA)) combinadas com antibióticos conhecidos (penicilina, ampicilina, amoxicilina/ácido clavulânico, cefoxitina, ciprofloxacina, cotrimoxazol e levofloxacina). O método utlizado foi o de microdiluição em placa, possibilitando assim, determinar a concentração mínima inibitória do crescimento bacteriano. Os resultados obtidos mostraram maiores sinergismos extratos-antibióticos em MRSA do que em E. coli. Os extratos de Mycena rosea e Fistulina hepatica foram os que revelaram mais efeitos sinérgicos para MRSA. A eficiência do extrato de Russula delica contra E. coli 1 (resistente à ampicilina, ciprofloxacina e trimetoprim/sulfasoxazole) e E. coli 2 (resistente à amoxicilina/ácido clavulânico e ampicilina) foi superior à do extrato de Leucopaxillus giganteus; no entanto, este demonstrou maiores efeitos sinérgicos contra E. coli produtora de β-lactamases.
- A review on antifungal activity of mushroom (basidiomycetes) extracts and isolated compoundsPublication . Alves, Maria José; Ferreira, Isabel C. F. R.; Dias, Joana; Teixeira, Vânia; Martins, Anabela; Pintado, ManuelaThe present review reports the antifungal activity of mushroom extracts and isolated compounds including high (e. g. peptides and proteins) and low (e. g. sesquiterpenes and other terpenes, steroids, organic acids, acylcyclopentenediones and quinolines) molecular weight compounds. Most of the studies available on literature focused on screening of antifungal activity of mushroom extracts, rather than of isolated compounds. Data indicate that mushroom extracts are mainly tested against different Candida species, while mushroom compounds are mostly tested upon other fungi. Therefore, the potential of these compounds might be more useful in food industry than in clinics. Oudemansiella canarii and Agaricus bisporus methanolic extracts proved to be the most active mushroom extracts against Candida spp. Grifolin, isolated from Albatrellus dispansus, seemed to be the most active compound against phytopathogenic fungi. Further studies should be performed in order to better understand the mechanism of action of this and other antifungal compounds as well as safety issues.
- A review on antimicrobial activity of mushroom (basidiomycetes) extracts and isolated compoundsPublication . Alves, Maria José; Ferreira, Isabel C. F. R.; Dias, Joana; Teixeira, Vânia; Martins, Anabela; Pintado, ManuelaDespite the huge diversity of antibacterial compounds, bacterial resistance to first-choice antibiotics has been drastically increasing. Moreover, the association between multiresistant microorganisms and nosocomial infections highlight the problem, and the urgent need for solutions. Natural resources have been exploited in the last years and among them, mushrooms could be an alternative source of new antimicrobials. In this review, we present an overview of the antimicrobial properties of mushroom extracts and highlight some of the active compounds identified, including low- and high-molecular weight (LMW and HMW, respectively) compounds. LMW compounds are mainly secondary metabolites, such as sesquiterpenes and other terpenes, steroids, anthraquinones, benzoic acid derivatives, and quinolines, but also primary metabolites such as oxalic acid. HMW compounds are mainly peptides and proteins. Data available from the literature indicate a higher antimicrobial activity of mushroom extracts against gram-positive bacteria. Among all the mushrooms, Lentinus edodes is the most studied species and seems to have a broad antimicrobial action against both grampostive and gram-negative bacteria. Plectasin peptide, obtained from Pseudoplectania nigrella, is the isolated compound with the highest antimicrobial activity against gram-positive bacteria, while 2-aminoquinoline, isolated from Leucopaxillus albissimus, presents the highest antimicrobial activity against gram-negative bacteria.
- Screening of the antimicrobial activity of wild mushrooms phenolic extracts against clinical isolatesPublication . Alves, Maria; Ferreira, Isabel; Martins, Anabela; Pintado, ManuelaAntimicrobial drugs have long been used for prophylactic and therapeutic purposes; however the drug-resistant bacterial strains have been creating serious treatment problems. This situation has forced the search of new antimicrobial substances effective against pathogenic microorganisms resistant to conventional treatments. Natural resources have been tested and among them mushrooms could be an alternative. This work aimed to screen the antimicrobial activity of phenolic extracts of 13 edible mushroom species, collected in Bragança, against several clinical isolates obtained in Hospital Center of Trás-os-Montes and Alto Douro, Portugal. Microdilution method was used to determine the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC). MIC results showed that Russula delica and Fistula hepática extracts inhibited the growth of Gram negative (Escherichia coli, Pasteurella multocida, Morganella morganni, isolated from urine) and Gram positive (Staphylococcus aureus, MRSA- isolated from wound exudates, Enterococcus faecalis, Listeria monocytogenes- isolated from blood culture, Streptococcus agalactiae and Streptococcus pyogenes- isolated from vaginal swab)bacteria. A bactericide effect of both extracts was observed in Gram positive bacteria (L. monocytogenes, S. agalactiae and S. pyogenes); regarding Gram negative bacteria, a total inhibition effect was observed for P. multocida at the highest concentration tested (20 mg/ml). Lepista nuda extract exhibited a bactericide effect upon P. multocida at 5 mg/ml, and inhibited Proteus mirabilis (isolated from urine) at 20 mg/ml. Ramaria botrytus extract did not present activity against Gram-negative bacteria; nevertheless, it showed activity against E. faecalis , being bactericide for S. agalactiae and S. pyogenes. Moreover, this was the extract with the highest activity against L. monocytogenes with MBC of 10 mg/ml. Leucopaxillus giganteus extract inhibited the growth of E. coli and P. mirabilis, being bactericide for P. multocida, L. monocytogenes, S. pyogenes and S. agalactiae. Among all the studied mushrooms, Agaricus arvensis seemed to present the lowest antimicrobial activity against all the tested bacteria. The extracts are chemically characterized and the individual/combined phenolic compounds will be submitted to antimicrobial assays in order to identify compounds responsible for the mushrooms bioactivity.
- Susceptibility to biofilm formation by clinical isolates from patients with urinary tract infection: development of a multifactorial predictive modelPublication . Alves, Maria José; Barreira, João C.M.; Ferreira, Isabel C.F.R.; Martins, Anabela; Pintado, M. E.Implantable medical devices help enhancing therapeutic results, saving human lives and improving life quality of patients. However, these devices can be readily colonized by bacteria and fungi, since the presence of a foreign body will reduce the number of microorganisms necessary to produce an infection (Guggenbichler et al., 2011). Accordingly, the aim of this study was to evaluate a group of biofilm producing bacteria isolated from patients with urinary tract infections, identifying the main factors contributing to biofilm formation. It was also intended to evaluate the association of these factors with biofilm formation, in order to understand their contribution as predictors for biofilm onset, allowing an earlier and more effective selection of the required antibiotic treatment. Biofilm detection was done by the tube adherence method. The investigation of the biofilm production was performed measuring its adherence to borosilicate test tubes following a previous methodology (Christensen et al., 1985) with minor changes. Among the 156 isolates, 58 (37.2%) were biofilm producers. The patient’s genre (p=0.022), together with bacterial species (p 0.001), were the factors with highest influence for biofilm production. In fact, some of the isolated bacteria were biofilm producer in all cases. The assayed factors (age, gender, hospital unit, bacteria and catheterization) were used to build a predictive model in order to anticipate biofilm occurrence immediately after bacterial identification. In this way, it is possible to select a more effective antibiotic (among the susceptibility options suggested by the antibiogram) against biofilm producing bacteria, avoiding the need to change antibiotics due to acquired resistance during the treatment. Regarding resistance profile among bacterial isolates, the β-lactamic antibiotics presented the highest cases/percentages: ampicillin (32/55.2%), cephalothin (30/ 51.7%), amoxicillin/clavulanic acid (22/37.9%), although the carbapenemic group still represent a good therapeutic option (2/3.4%). Quinolones (nucleic acid synthesis inhibitors) also showed high resistance percentages. Furthermore, biofilm production clearly increases bacterial resistance. Actually, almost half of biofilm producing bacteria showed resistance against at least three different species.
- Synergistic effects between wild mushroom extracts and standard antibiotics against multi-resistant bacteriaPublication . Alves, Maria José; Ferreira, Isabel C. F. R.; Martins, Anabela; Pintado, M. E.
- Wild mushroom extracts as inhibitors of bacterial biofilm formationPublication . Alves, Maria José; Ferreira, Isabel C. F. R.; Lourenço, Inês; Costa, Eduardo; Martins, Anabela; Pintado, ManuelaMicroorganisms can colonize a wide variety of medical devices, putting patients in risk for local and systemic infectious complications, including local-site infections, catheter-related bloodstream infections, and endocarditis. These microorganisms are able to grow adhered to almost every surface, forming architecturally complex communities termed biofilms. The use of natural products has been extremely successful in the discovery of new medicine, and mushrooms could be a source of natural antimicrobials. The present study reports the capacity of wild mushroom extracts to inhibit in vitro biofilm formation by multi-resistant bacteria. Four Gram-negative bacteria biofilm producers (Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, and Acinetobacter baumannii) isolated from urine were used to verify the activity of Russula delica, Fistulina hepatica, Mycena rosea, Leucopaxilus giganteus, and Lepista nuda extracts. The results obtained showed that all tested mushroom extracts presented some extent of inhibition of biofilm production.Pseudomonas aeruginosa was the microorganism with the highest capacity of biofilm production, being also the most susceptible to the extracts inhibition capacity (equal or higher than 50%). Among the five tested extracts against E. coli, Leucopaxillus giganteus (47.8%) and Mycenas rosea (44.8%) presented the highest inhibition of biofilm formation. The extracts exhibiting the highest inhibitory effect upon P. mirabilis biofilm formation were Sarcodon imbricatus (45.4%) and Russula delica (53.1%). Acinetobacter baumannii was the microorganism with the lowest susceptibility to mushroom extracts inhibitory effect on biofilm production (highest inhibition—almost 29%, by Russula delica extract). This is a pioneer study since, as far as we know, there are no reports on the inhibition of biofilm production by the studied mushroom extracts and in particular against multi-resistant clinical isolates; nevertheless, other studies are required to elucidate the mechanism of action.