Browsing by Author "Dias, Carla"
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- Antagonistic activities of Kefirgel and Kefirgel products against Staphylococcus aureus isolated from diabetic ulcersPublication . Zenão, S.; Aires, Alfredo; Dias, Carla; Saavedra, Maria José; Fernandes, ConceiçãoDiabetic foot ulcers are often complicated by infection and among pathogens the Gram-positive Staphylococcus aureus is the most common isolated. Also concomitantly, the high prevalence of methicillin-resistant S. aureus (MRSA) was significant impact on successful treatment of infected foot ulcers. In this context, the purpose of the present study was to evaluate the antibacterial properties of Kefigel®, a natural product composed by nettle (Urtica dioica L), lavender (Lavandula angustifolia Mill) and kefir grains, which have been reported as to having antibacterial activity against several diseases. Here, antibacterial effect of Kefigel® and its components were investigated against 20 S. aureus isolates (10 MSSA and 10 MRSA) collected from several diabetic foot ulcers. To assess antibacterial activity, the disk diffusion assay method, minimum inhibitory concentration (MIC), minimal bacterial activity and effects on specific growth rate, were applied. Results showed that by diffusion method, only etanolic extracts of nettle and lavender showed antibacterial activity and their effects were mainly bacteriostatic. Compared to the antibiotic gentamicin, the nettle and lavender extracts showed an efficacy between 50 and 100% relative to the antibiotic. Generally, the MRSA isolates sowed higher inhibition halos comparing MSSA isolates. In turns, Kefigel® (40mg.mL-1) affects the specific growth rate of S. aureus isolates, since after incubation for 9h almost MSSA isolates growth were inhibited. A bactericide effect was observed only against one isolates MRSA. These findings indicate a potential use of Kefigel® as a natural product having an effective effect against Staphylococus aureus. The topical use of this product for prevention of diabetic foot ulcers infections can be useful, however further investigation will be made, namely tests with high Kefigel® concentrations and synergetic effects with antibiotics.
- Antibacterial potential of Urtica dioica and Lavandula angustifolia extracts against methicillin resistant Staphylococcus aureus isolated from diabetic foot ulcersPublication . Zenão, S.; Aires, Alfredo; Dias, Carla; Saavedra, Maria José; Fernandes, ConceiçãoDespite the antibacterial potential of plant extracts against several bacterial infections, until now, no major studies have been published about the effect of lavender and nettle leaves against methicillin-sensitive and methicillin-resistant strains of Staphylococcus aureus (MSSA and MRSA, respectively). Thus, the authors studied their antibacterial potential against MSSA and MRSA from diabetic foot ulcers in order to find alternatives to the systematic use of antibiotics. Phenolic acids, flavonoids, flavones and flavonols were extracted from lavender and nettle leaves and characterized by HPLC-DAD/Vis. Disc diffusion assay and minimum inhibitory concentration (MIC) were used to assess their antibacterial activity. A direct association between the high content of hydroxycinnamic acids (chlorogenic acid, caffeic acid, rosmarinic acid) and flavonoids (quercetin) and decreasing bacterial growth activity was noted. The fact that lavender and nettle are rich in hydroxycinnamic acids and quercetin seems to explain the high antibacterial potential of these plant and the differences between them.
- Antibacterial screening of active ethanolic fractions of Urtia dioica L. against pathogenic bacteria from gastrointestinal and respiratory tractPublication . Aires, Alfredo; Dias, Carla; Zenão, S.; Rosa, Eduardo; Fernandes, Conceição; Saavedra, Maria JoséMedicinal plants are largely explored source of drug repository. Although a huge number of antibiotics are available for treatment of microbial infections, development of resistance mechanism against antibiotics is nowadays a major health concern. Therefore the needs of discover new antimicrobial compounds with high safety index is always recurrent and medicinal plants have great potential for providing novel drug leads with novel mechanism of action. Historically, this plants have always been a source of inspiration for new drug compounds. In this context we evaluate the antimicrobial potential of various extracts (produced by a partial purification in a silica gel column) of Urtica dioica L (stinging nettle) (Urticaceae) collected from Vila Real region (Portugal), against 10 different bacteria isolates collected from clinical patients (gastrointestinal segments and respiratory tract), namely 4 Gram positive [2 Staphylococcus aureus (MRSA), Staphylococus aureus (MSSA), Staphylococcus saprophyticus, and Enterococcus faecalis]and 5 Gram negative[Salmonella thyphi, Echerichia coli, Klebsiela pneumoniae, Pseudomonas aeruginosa and Proteus mirabilis]. The current study represents the investigation of antimicrobial activity of U. dioica from four fractions (Hexane, Ethyl-acetate, ethanol and water) that were prepared using sequential fractionating method by column chromatography. The antibacterial activity was assessed by disk diffusion and minimum inhibitory concentration methods. The phytochemical composition of U. dioica fractions were assessed by HPLC-UV-DAD. Our results showed that only ethanolic fractions had antibacterial activity but only in S. aureus (MRSA and MSSA), S. saprophyticus and E. faecallis isolates. Thus, only the Gram positives were affected by U.doica extracts. The inhibition zone diameter halos ranges from 0 to 23 mm and the minimum inhibitory concentration (MIC) were6.25 mg.mL-1 for MRSA isolates and 0.78 mg.mL-1 for S. saprophyticus and E. faecalis. Our results show a direct association between the antibacterial activities and high content of phytochemicals detected in the ethanolic fractions particularly with phenolic acids (chlorogenic and ferulic acids) and flavonols (rutin, isoquercetin and quercetin isomers). Our observations suggest the importance of ethnomedicinal use of U. dioica, which could be used by the pharmaceutical industry as source of a natural antimicrobial agents and antioxidant compounds.
- Effects of olive leaf on gut microflora of broiler poultryPublication . Mourão, José L.; Pereira, Ermelinda; Pinheiro, Victor; Dias, Carla; Freitas, Eliana; Pereira, Vânia; Saavedra, Maria JoséIn 2006 European Union bans the use of antibiotics as growth promoters (AGP) in animal feed. Due to the fact that the use of antibiotics as growth promoters has been banned intensive research has focused on the development of alternative strategies with the aim of maintenance of animal health and performance. Some studies showed that olive leaves have specific organic compounds with antimicrobial activities. The objective of the present essay is to evaluate the effects of olive leaf (OL) diet incorporation on intestinal microflora of broiler poultries. The three experimental treatments were as follow: control treatment (0FO); 10FO (10 g/kg of olive leaf); 20FO (20 g/kg of olive leaf). The basal diet (control treatment) was a typical corn and soybean meal-based diet and was formulated according to the recommendation of NRC (1994). One hundred and forty-seven day old male feather sexed broiler chicks (Ross 350) were allocated randomly in 21 pens (7 birds/pen). The chicks were given feed and water ad libitum throughout the experimental period (0 to 21 days of age). At 21 days of age, 2 birds of each pen randomly selected were removed and a total of 60 birds were slaughtered to collect the ileal and caecal contents counting of microbial population (total coliforms and Escherichia coli). The results showed a lower total coliforms and E. coli counts in ileum contents than in cecal contents. The addition of olive leaf in basal diet did not affect the population of coliforms and E. coli in ileum and cecal contents.
- Susceptibilidade a antibióticos em isolados bacterianos do ambiente em lares de 3ª idadePublication . Amaro, Andreia Inês Alves; Saavedra, Maria José; Dias, Carla; Fernandes, ConceiçãoO envelhecimento populacional traz um número vasto de implicações que incluem, entre outras, condições de baixa imunidade e por isso maior risco de infecções. Algumas situações podem contribuir para aumentar esse risco, nomeadamente má ventilação, aglomerado populacional, condições de humidade e fraca higienização. O tratamento das infecções passa pela administração criteriosa de antibióticos. A identificação de espécies e estirpes é de grande importância, assim como a indicação adequada dos antibióticos. Nesse sentido, o Sistema Europeu de Vigilância da Resistência Antimicrobiana (EARSS) alerta para o desenvolvimento de bactérias resistentes aos antibióticos com consequências importantes na redução da eficácia dos mesmos. Assim, o objectivo geral deste trabalho foi o de isolar e caracterizar estirpes bacterianas de Gram positivo provenientes de isolados ambientais em Lares de 3ª idade, bem como descrever o seu perfil de resistência a diversos grupos de antibióticos. Como complemento, estudou-se também a sua susceptibilidade a dois tipos de desinfectantes comummente utilizados.