Caracterização do microbioma e dos perfis de resistência nos afluentes e efluentes de ETAR

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)

Bacterial vaginosis biofilms: challenges to current therapies and emerging solutions

Bacterial vaginosis (BV) is the most common genital tract infection in women during their reproductive years and it has been associated with serious health complications, such as preterm delivery and acquisition or transmission of several sexually transmitted agents. BV is characterized by a reduction of beneficial lactobacilli and a significant increase in number of anaerobic bacteria, including Gardnerella vaginalis, Atopobium vaginae, Mobiluncus spp., Bacteroides spp. and Prevotella spp.. Being polymicrobial in nature, BV etiology remains unclear. However, it is certain that BV involves the presence of a thick vaginal multi-species biofilm, where G. vaginalis is the predominant species. Similar to what happens in many other biofilm-related infections, standard antibiotics, like metronidazole, are unable to fully eradicate the vaginal biofilm, which can explain the high recurrence rates of BV. Furthermore, antibiotic therapy can also cause a negative impact on the healthy vaginal microflora. These issues sparked the interest in developing alternative therapeutic strategies. This review provides a quick synopsis of the currently approved and available antibiotics for BV treatment while presenting an overview of novel strategies that are being explored for the treatment of this disorder, with special focus on natural compounds that are able to overcome biofilm-associated antibiotic resistance.

Peptaibolin analogues by incorporation of α,α-dialkylglycines: synthesis and study of their membrane permeating ability

Analogues of Peptaibolin, a peptaibol with antibiotic activity, incorporating α,α-dialkylglycines (Deg, Dpg, and Ac6c) at selected positions were synthesised by MW-SPPS and fully characterized. A control analogue incorporating L-alanine was also prepared. The native peptide and the analogues were studied by fluorescence spectroscopy for their membrane permeating activity. Small unilamellar vesicles (SUVs) of egg phosphatidylcholine/ cholesterol (70:30) containing an encapsulated fluorescence probe (6-carboxyfluorescein) were used as membrane models. The assays of carboxyfluorescein release from SUVs upon peptide addition showed that Peptaibolin-Dpg and Peptaibolin-Ac6c are the most active peptides. These results indicate that the structure of the α,α-dialkylglycines is crucial for the membrane permeating ability of these Peptaibolin analogues.

Strategies to combat infections of Acinetobacter baumannii biofilms

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)

Pseudomonas aeruginosa diversification during infection development in cystic fibrosis lungs

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)

Prevalência e susceptibilidade de isolados clínicos de Pseudomonas aeruginosa numa unidade hospitalar de Portugal

Dissertação de mestrado em Bioquímica Aplicada (área de especialização em Biomedicina)

The relevance of bacterial interactions on oral health

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)

Removal of tetracycline from contaminated water by Moringa oleifera seed preparations

The aim of this study was to evaluate tetracycline antibiotic (TA) removal from contaminated water by Moringa oleifera seed preparations. The composition of synthetic water approximate river natural contaminated water and TA simulated its presence as an emerging pollutant. Interactions between TA and protein preparations (extract; fraction and lectin) were also evaluated. TA was determined by solid phase extraction followed by high performance liquid chromatography - mass spectrometry. Moringa extract and flour removed TA from water. Extract removed TA in all concentrations and better removal (40%) was obtained with 40 mg L1; seed flour (particles < 5mm), 1.25 g L1 and 2.50 g L1 removed 28 and 29% of tetracycline, respectively; particles > 5 mm (0.50 g L1) removed 55% of antibiotic. Interactions between TA and seed preparations were assayed by haemagglutinating activity (HA). Specific HA (SHA) of extract (pH 7) was abolished with tetracycline (5 mg L1); fraction (75%) and lectin HA (97%) were inhibited with TA. Extract SHA decreased by 75% at pH 8. Zeta potential (ZP) of extract 700 mg L1 and tetracycline 50 mg L1 , pH range 5 to 8, showed different results. Extract ZP was more negative (10.73 mV to 16.00 mV) than tetracycline ZP (0.27 mV to 20.15 mV); ZP difference was greater in pH 8. The focus of this study was achieved since moringa preparations removed TA from water and compounds interacting with tetracycline involved at least lectin binding sites. This is a natural process, which do not promote environmental damage.

Characterization of an in vitro fed-batch model to obtain cells released from S. epidermidis biofilms

Both dynamic and fed-batch systems have been used for the study of biofilms. Dynamic systems, whose hallmark is the presence of continuous flow, have been considered the most appropriate for the study of the last stage of the biofilm lifecycle: biofilm disassembly. However, fed-batch is still the most used system in the biofilm research field. Hence, we have used a fed-batch system to collect cells released from Staphylococcus epidermidis biofilms, one of the most important etiological agents of medical device-associated biofilm infections. Herein, we showed that using this model it was possible to collect cells released from biofilms formed by 12 different S. epidermidis clinical and commensal isolates. In addition, our data indicated that biofilm disassembly occurred by both passive and active mechanisms, although the last occurred to a lesser extent. Moreover, it was observed that S. epidermidis biofilm-released cells presented higher tolerance to vancomycin and tetracycline, as well as a particular gene expression phenotype when compared with either biofilm or planktonic cells. Using this model, biofilm-released cells phenotype and their interaction with the host immune system could be studied in more detail, which could help providing significant insights into the pathophysiology of biofilm-related infections.

Treatment of persistent rejection with methotrexate in stable patients submitted to heart transplantation

OBJECTIVE:To evaluate the use of methotrexate for the treatment of recurrent rejection in heart transplant recipients. METHODS: We studied 6 patients submitted to heart transplantation that showed rejection grade > or = 3A (ISHLT) in two consecutives endomyocardial biopsy specimens. The dose was 11.26±3.75mg/week. The evaluated data were: ventricular function, endomyocardial biopsy, white cell count and number of rejection episodes before and after methotrexate administration. RESULTS: There was a reduction in the number of rejection episodes (5.17±1.47 before methotrexate; 2.33±1.75 after 6 months and 3.17±2.99 after 12 months of treatment, p=0.0193). The ventricular function was normal with ejection fraction of 76.5±4.80 before and 75.6±4.59 after methotrexate (p=0.4859). One patient did not finish the treatment because he showed signs of rejection associated with severe pericardial effusion. Five patients had a reduction in the white cell count (8,108±23.72 before and 5650±1350 after methotrexate, p=0.0961). One pulmonary infection with complete resolution after antibiotic treatment was observed. CONCLUSION: Methotrexate in low doses is an effective adjunct therapy in the treatment of recurrent rejection after heart transplantation.

Silver nanoparticles to fight Candida coinfection in the oral cavity

[Exert] This chapter is focused on the activity of silver nanoparticles (SN) as an antifungal agent against Candida albicans and Candida glabrata biofilms, which are involved in oral candidosis. A discussion focusing on the influence of the stabilizing agent, diameter of SN on its antibiofilm activity, influence of chemical stability of SN on Candida biofilms, the effect of SN against adhered cells and biofilms, the effect on extracellular matrix composition and structure of Candida biofilms, the combination of SN with conventional antifungal drugs, and the incorporation of SN into denture acrylic resin is incorporated in the present chapter. Because of the resistance of Candida biofilms to conventional drugs and the positive effect of SN against them, these nanoparticles can be used as an alternative antifungal agent (...).

Mediastinitis after cardiac transplantation

OBJECTIVE: Assessment of incidence and behavior of mediastinitis after cardiac transplantation. METHODS: From 1985 to 1999, 214 cardiac transplantations were performed, 12 (5.6%) of the transplanted patients developed confirmed mediastinitis. Patient's ages ranged from 42 to 66 years (mean of 52.3±10.0 years) and 10 (83.3%) patients were males. Seven (58.3%) patients showed sternal stability on palpation, 4 (33.3%) patients had pleural empyema, and 2 (16.7%) patients did not show purulent secretion draining through the wound. RESULTS: Staphylococcus aureus was the infectious agent identified in the wound secretion or in the mediastinum, or both, in 8 (66.7%) patients. Staphylococcus epidermidis was identified in 2 (16.7%) patients, Enterococcus faecalis in 1 (8.3%) patient, and the cause of mediastinitis could not be determined in 1 (8.3%) patient. Surgical treatment was performed on an emergency basis, and the extension of the débridement varied with local conditions. In 2 (16.7%) patients, we chose to leave the surgical wound open and performed daily dressings with granulated sugar. Total sternal resection was performed in only 1 (8.3%) patient. Out of this series, 5 (41.7%) patients died, and the causes of death were related to the infection. Autopsy revealed persistence of mediastinitis in 1 (8.3%) patient. CONCLUSION: Promptness in diagnosing mediastinitis and precocious surgical drainage have changed the natural evolution of this disease. Nevertheless, observance of the basic precepts of prophylaxis of infection is still the best way to treat mediastinitis.

Zeolite-based nanomaterials for the control of opportunistic pathogenic microorganisms

Dissertação de mestrado em Applied Biochemistry (área de especialização em Biomedicine)

Immunologic evaluation in infective endocarditis

OBJECTIVE: To analyze the immune response in peripheral blood of patients with infective endocarditis. METHODS: We studied 10 patients with infective endocarditis, age range from 20 to 50 years-old, males and females, and 20 healthy subjects in the same age range. The diagnosis of the disease was based on the clinical picture, echocardiogram, and hemoculture based upon samples drawn and tested before the treatment started. The were no history of atopy or malnutrition, no autoimmune disease, and they were not using any immunosuppressant or antibiotic medication. RESULTS: The patients with endocarditis had significantly higher T and B lymphocyte, CD4+ and CD8+ cell counts, IgM and IgG serum levels, and C4 component of the complement than the control group; no significant difference concerning serum IgA and neutrophil oxidative metabolism; a significant decrease in C3, chemotaxis, and monocyte phagocytosis;cryoglobulins were detected in 66.6% of patients and they were formed by IgG, IgM, IgA, C3, and C4. CONCLUSION: The patients with infective endocarditis were immunocompetent in most sectors of immune response and, at a certain moment, an autoimmune component may be present.

Control of bovine mastitis: old and recent therapeutic approaches

Mastitis is defined as the inflammatory response resulting of the infection of the udder tissue and it is reported in numerous species, namely in domestic dairy animals. This pathology is the most frequent disease of dairy cattle and can be potentially fatal. Mastitis is an economically important pathology associated with reduced milk production, changes in milk composition and quality, being considered one of the most costly to dairy industry. Therefore, the majority of research in the field has focused on control of bovine mastitis and many efforts are being made for the development of new and effective anti-mastitis drugs. Antibiotic treatment is an established component of mastitis control programs; however, the continuous search for new therapeutic alternatives, effective in the control and treatment of bovine mastitis, is urgent. This review will provide an overview of some conventional and emerging approaches in the management of bovine mastitis infections.