Synthesis of acyl thiourea derivatives of chitosan and their antimicrobial activities in vitro

Three different acyl thiourea derivatives of chitosan (CS) were synthesized and their structures were characterized by FT-IR spectroscopy and elemental analysis. The antimicrobial behaviors of CS and its derivatives against four species of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Sarcina) and four crop-threatening pathogenic fungi (Alternaria solani, Fusarium oxysporum f. sp. vasinfectum, Colletotrichum gloeosporioides (Penz.) Saec, and Phyllisticta zingiberi) were investigated. The results indicated that the antimicrobial activities of the acyl thiourea derivatives are much better than that of the parent CS. The minimum value of MIC and MBC of the derivatives against E coli was 15.62 and 62.49 mu g/mL, respectively. All of the acyl thiourea derivatives had a significant inhibitory effect on the fungi in concentrations of 50 - 500 mu g/mL; the maximum inhibitory index was 66.67%. The antifungal activities of the chloracetyl thiourea derivatives of CS are noticeably higher than the acetyl and benzoyl thiourea derivatives. The degree of grafting of the acyl thiourea group in the derivatives was related to antifungal activity; higher substitution resulted in stronger antifungal activity. (c) 2007 Elsevier Ltd. All rights reserved.

Valve surgery in active infective endocarditis: a simple score to predict in-hospital prognosis

Aims Surgery for infective endocarditis (IE) is associated with high mortality. Our objectives were to describe the experience with surgical treatment for IE in Spain, and to identify predictors of in-hospital mortality. Methods Prospective cohort of 1000 consecutive patients with IE. Data were collected in 26 Spanish hospitals. Results Surgery was performed in 437 patients (43.7%). Patients treated with surgery were younger and predominantly male. They presented fewer comorbid conditions and more often had negative blood cultures and heart failure. In-hospital mortality after surgery was lower than in the medical therapy group (24.3 vs 30.7%, p = 0.02). In patients treated with surgery, endocarditis involved a native valve in 267 patients (61.1%), a prosthetic valve in 122 (27.9%), and a pacemaker lead with no clear further valve involvement in 48 (11.0%). The most common aetiologies were Staphylococcus (186, 42.6%), Streptococcus (97, 22.2%), and Enterococcus (49, 11.2%). The main indications for surgery were heart failure and severe valve regurgitation. A risk score for in-hospital mortality was developed using 7 prognostic variables with a similar predictive value (OR between 1.7 and 2.3): PALSUSE: prosthetic valve, age ≥ 70, large intracardiac destruction, Staphylococcus spp, urgent surgery, sex [female], EuroSCORE ≥ 10. In-hospital mortality ranged from 0% in patients with a PALSUSE score of 0 to 45.4% in patients with PALSUSE score > 3. Conclusions The prognosis of IE surgery is highly variable. The PALSUSE score could help to identify patients with higher in-hospital mortality.

Towards the identification of the common features of bacterial biofilm development

UPNa. Instituto de Agrobiotecnología. Laboratorio de Biofilms Microbianos

RinA controls phage-mediated packaging and transfer of virulence genes in gram-positive bacteria

Phage-mediated transfer of microbial genetic elements plays a crucial role in bacterial life style and evolution. In this study, we identify the RinA family of phage-encoded proteins as activators required for transcription of the late operon in a large group of temperate staphylococcal phages. RinA binds to a tightly regulated promoter region, situated upstream of the terS gene, that controls expression of the morphogenetic and lysis modules of the phage, activating their transcription. As expected, rinA deletion eliminated formation of functional phage particles and significantly decreased the transfer of phage and pathogenicity island encoded virulence factors. A genetic analysis of the late promoter region showed that a fragment of 272 bp contains both the promoter and the region necessary for activation by RinA. In addition, we demonstrated that RinA is the only phage-encoded protein required for the activation of this promoter region. This region was shown to be divergent among different phages. Consequently, phages with divergent promoter regions carried allelic variants of the RinA protein, which specifically recognize its own promoter sequence. Finally, most Gram-postive bacteria carry bacteriophages encoding RinA homologue proteins. Characterization of several of these proteins demonstrated that control by RinA of the phage-mediated packaging and transfer of virulence factor is a conserved mechanism regulating horizontal gene transfer.

Badania spektroskopowe, strukturalna i aktywność przeciwdrobnoustrojowa nowych soli kwasu lasalowego z aminami

Wydział Chemii

Bactérias e as suas redes sociais

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Infeções em Cateteres de Hemodialisados

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Nutraceutical and functional food bioactive peptides in beef

In recent years, the potential to positively modulate human health through dietary approaches has received considerable attention. Bioactive peptides which are released during the hydrolysis or fermentation of food proteins or following digestion may exert beneficial physiological effects in vivo. The aim of this work was to isolate, characterise and evaluate Angiotensin-І-converting enzyme (ACE-І) inhibitory, antimicrobial and antioxidant peptides from the bovine myofibrillar proteins actin and myosin. In order to generate these peptides, the myofibrillar proteins actin and myosin were hydrolysed with digestive enzymes pepsin, trypsin and α-chymotrypsin, or with the industrial thermolysin-like enzyme “Thermoase”, Amano Inc. It was found that each hydrolysate generated contained peptides which possessed ACE inhibitory, antioxidant and antimicrobial activity. The peptides responsible in part for the observed ACE inhibitory, antioxidant and antimicrobial activity of a number of hydrolysates were isolated using the method of RP-HPLC and the bioactive peptides contained within each active fraction was determined using either MALDI-TOF MS/MS or N-terminal peptide sequencing. During the course of this thesis six ACE inhibitory and five antimicrobial peptides were identified. It was determined that the reported antioxidant activity was a direct result of a number of peptides working in synergy with each other. The IC50 values of the six ACE inhibitory peptides ranged in values of 6.85 to 75.7 µM which compare favourably to values previously reported for other food derived ACE inhibitory peptides, particularly the well known milk peptides IPP and VPP, IC50 values of 5 and 9 µM respectively. All five antimicrobial peptides identified in this thesis displayed activity against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Listeria innocua with MIC values ranging from 0.625 to10 mM. The activity of each antimicrobial peptide was strain specific. Furthermore the role and importance of charged amino acids to the activity of antimicrobial peptides was also determined. Generally the removal of charged amino acids from the sequence of antimicrobial peptides resulted in a loss of antimicrobial activity. In conclusion, this thesis revealed that a range of bioactive peptides exhibiting ACE inhibitory, antioxidant and antimicrobial activities were encrypted in bovine myofibrillar proteins that could be released using digestive and industrial enzymes. Finally enzymatic hydrolysates of muscle proteins could potentially be incorporated into functional foods; however, the potential health benefits would need to be proven in human clinical studies.

Integrated analysis of CANVAS 1 and 2: phase 3, multicenter, randomized, double-blind studies to evaluate the safety and efficacy of ceftaroline versus vancomycin plus aztreonam in complicated skin and skin-structure infection.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of complicated skin and skin-structure infection (cSSSI). Increasing antimicrobial resistance in cSSSI has led to a need for new safe and effective therapies. Ceftaroline was evaluated as treatment for cSSSI in 2 identical phase 3 clinical trials, the pooled analysis of which is presented here. The primary objective of each trial was to determine the noninferiority of the clinical cure rate achieved with ceftaroline monotherapy, compared with that achieved with vancomycin plus aztreonam combination therapy, in the clinically evaluable (CE) and modified intent-to-treat (MITT) patient populations. METHODS: Adult patients with cSSSI requiring intravenous therapy received ceftaroline (600 mg every 12 h) or vancomycin plus aztreonam (1 g each every 12 h) for 5-14 days. RESULTS: Of 1378 patients enrolled in both trials, 693 received ceftaroline and 685 received vancomycin plus aztreonam. Baseline characteristics of the treatment groups were comparable. Clinical cure rates were similar for ceftaroline and vancomycin plus aztreonam in the CE (91.6% vs 92.7%) and MITT (85.9% vs 85.5%) populations, respectively, as well as in patients infected with MRSA (93.4% vs 94.3%). The rates of adverse events, discontinuations because of an adverse event, serious adverse events, and death also were similar between treatment groups. CONCLUSIONS: Ceftaroline achieved high clinical cure rates, was efficacious against cSSSI caused by MRSA and other common cSSSI pathogens, and was well tolerated, with a safety profile consistent with the cephalosporin class. Ceftaroline has the potential to provide a monotherapy alternative for the treatment of cSSSI. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT00424190 for CANVAS 1 and NCT00423657 for CANVAS 2.

Suppression of conformational heterogeneity at a protein-protein interface.

Staphylococcal protein A (SpA) is an important virulence factor from Staphylococcus aureus responsible for the bacterium's evasion of the host immune system. SpA includes five small three-helix-bundle domains that can each bind with high affinity to many host proteins such as antibodies. The interaction between a SpA domain and the Fc fragment of IgG was partially elucidated previously in the crystal structure 1FC2. Although informative, the previous structure was not properly folded and left many substantial questions unanswered, such as a detailed description of the tertiary structure of SpA domains in complex with Fc and the structural changes that take place upon binding. Here we report the 2.3-Å structure of a fully folded SpA domain in complex with Fc. Our structure indicates that there are extensive structural rearrangements necessary for binding Fc, including a general reduction in SpA conformational heterogeneity, freezing out of polyrotameric interfacial residues, and displacement of a SpA side chain by an Fc side chain in a molecular-recognition pocket. Such a loss of conformational heterogeneity upon formation of the protein-protein interface may occur when SpA binds its multiple binding partners. Suppression of conformational heterogeneity may be an important structural paradigm in functionally plastic proteins.

Phenolic compounds, antioxidant and antibacterial activities of three Ericaceae from Algeria

Herbs of the Ericaceae family are commonly found in Algeria and used in traditional medicine as anti- septic, diuretic, astringent, depurative, and to treat scalds and wounds. The methanolic extracts of three species, Arbutus unedo L. (A. unedo, leaves), Erica arborea L. (E. arborea, flowered aerial parts), and Erica multiflora L. (E. multiflora, flowered aerial parts), were compared regarding their content in pheno- lic compounds, their antioxidant, and antibacterial activities. A. unedo harbors the highest content in total phenolics and flavonoids, followed by E. arborea E. multiflora. The contents in total phenolics and flavonoids showed a correlation with the measured antioxidant (hydrogen-donating) activities; this was particularly the case for flavonoids content. The A. unedo extract showed antibacterial activity against all the tested strains (Staphylococcus aureus ATCC 6538, S. aureus C100459, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 9027); however, the E. arborea and E. multiflora extracts showed antibacterial activity only against Gram positive bacteria. Some polyphenols were identified in the three herbs by thin-layer chromatography and high-performance liquid chromatography coupled with diode array and mass spectrometry detection; from these, caffeic acid, p-coumaric acid, naringin, quercetin and kaempferol are reported for the first time in E. multiflora.

Ag+- and Zn2+-exchange kinetics and antimicrobial properties of 11 angstrom tobermorites

Ag+- and Zn2+-exchanged zeolites zeolites and clays have been used as coatings and in composites to confer broad-spectrum antimicrobial properties on a range of technical and biomedical materials. 11 angstrom tobermorite is a bioactive layer lattice ion exchanger whose potential as a carrier for Ag+ and Zn2+ ions in antimicrobial formulations has not yet been explored. In view of this, batch Ag+- and Zn2+-exchange kinetics of two structurally distinct synthetic 11 angstrom tobermorites and their subsequent bactericidal action against Staphylococcus aureus and Pseudomonas aeruginosa are reported. During the exchange reactions, Ag+ ions were found to replace labile interlayer cations; whereas, Zn2+ ions also displaced structural Ca2+ ions from the tobermorite lattice. In spite of these different mechanisms, a simple pseudo-second-order model provided a suitable description of both exchange processes (R-2 >= 0.996). The Ag+- and Zn2+-exchanged tobermorite phases exhibited marked bacteriostatic effects against both bacteria, and accordingly, their potential for use as antimicrobial materials for in situ bone tissue regeneration is discussed. (C) 2008 Elsevier Ltd. All rights reserved.

Detection of Emerging and Re-Emerging Pathogens in Surface Waters Close to an Urban Area

Current knowledge about the spread of pathogens in aquatic environments is scarce probably because bacteria, viruses, algae and their toxins tend to occur at low concentrations in water, making them very difficult to measure directly. The purpose of this study was the development and validation of tools to detect pathogens in freshwater systems close to an urban area. In order to evaluate anthropogenic impacts on water microbiological quality, a phylogenetic microarray was developed in the context of the EU project µAQUA to detect simultaneously numerous pathogens and applied to samples from two different locations close to an urban area located upstream and downstream of Rome in the Tiber River. Furthermore, human enteric viruses were also detected. Fifty liters of water were collected and concentrated using a hollow-fiber ultrafiltration approach. The resultant concentrate was further size-fractionated through a series of decreasing pore size filters. RNA was extracted from pooled filters and hybridized to the newly designed microarray to detect pathogenic bacteria, protozoa and toxic cyanobacteria. Diatoms as indicators of the water quality status, were also included in the microarray to evaluate water quality. The microarray results gave positive signals for bacteria, diatoms, cyanobacteria and protozoa. Cross validation of the microarray was performed using standard microbiological methods for the bacteria. The presence of oral-fecal transmitted human enteric-viruses were detected using q-PCR. Significant concentrations of Salmonella, Clostridium, Campylobacter and Staphylococcus as well as Hepatitis E Virus (HEV), noroviruses GI (NoGGI) and GII (NoGII) and human adenovirus 41 (ADV 41) were found in the Mezzocammino site, whereas lower concentrations of other bacteria and only the ADV41 virus was recovered at the Castel Giubileo site. This study revealed that the pollution level in the Tiber River was considerably higher downstream rather than upstream of Rome and the downstream location was contaminated by emerging and re-emerging pathogens.

The Relationship between Hospital Infection Surveillance and Control Activities and Antibiotic Resistant Pathogen Rates

Objective: The purpose of the study was to examine the relationship of surveillance and control activities in Canadian hospitals with rates of nosocomial methicillin-resistant S. aureus (MRSA), C. difficile associated diarrhea (CDAD), and vancomycin-resistant Enterococcus (VRE). Methods: Surveys were sent to Infection Control programs in hospitals that participated in an earlier survey of infection control practices in Canadian acute care hospitals. Results: One hundred and twenty of 145 (82.8%) hospitals responded to the survey. The mean MRSA rate was 2.0 (SD 2.9) per 1,000 admissions, the mean CDAD rate was 3.8 (SD 4.3), and the mean VRE rate was 0.4 (SD 1.5). Multiple stepwise regression analysis found hospitals that reported infection rates by specific risk groups (r = - 0.27, p < 0.01) and that kept attendance records of infection control teaching activities (r = - 0.23, p < 0.01) were associated with lower MRSA rates. Multiple stepwise regression analysis found larger hospitals (r = 0.25, p < 0.01) and hospitals where infection control committees or staff had the direct authority to close a ward or unit to further admissions due to outbreaks (r = 0.22, p < 0.05) were associated with higher CDAD rates. Multiple logistic regression analysis found larger hospitals (OR = 1.6, CI 1.2 - 2.0, p = 0.003) and teaching hospitals (OR = 3.7, CI 1.2 - 11.8, p = 0.02) were associated with the presence of VRE. Hospitals were less likely to have VRE when infection control staff frequently contacted physicians and nurses for reports of new infections (OR = 0.5, CI 0.3 - 0.7, p = 0.02) and there were in-service programs for updating nursing and ancillary staff on current infection control practices (OR = 0.2, CI 0.1 - 0.7, p = 0.01). Conclusions: Surveillance and control activities were associated with MRSA and CDAD rates and the presence of VRE. Surveillance and control activities might be especially beneficial in large and teaching hospitals.

A polysaccharide extracted from sphagnum moss as antifungal agent in archaeological conservation

On the basis of the well-known preservative properties of Sphagnum moss, a potential opportunity to use moss polysaccharides (Sphagnan) in art conservation was tested. Polysaccharides were extracted from the moss (S. palustre spp.) in the amount of 4.1% of the Sphagnum plant dry weight. All lignocelluloses were removed from this extract as a result of the treatment of the moss cellulose with sodium chlorite. The extracted polysaccharide possessed a strong acidic reaction (pH 2.8) and was soluble in water and organic solvents. The extract was tested on laboratory bacterial cultures by the disk-diffusion method. The antibacterial effect was demonstrated for E. coli and P. aeruginosa (both gram-negative) while Staphylococcus aurelus (gram-positive) was shown to be insensitive to Sphagnum polysaccharides. The antifungal effect of Sphagnum extract was tested by the disk-diffusion method on the spores of seventeen fungal species. These fungi were isolated from ethnographic museum objects and from archaeological objects excavated in the Arctic. Twelve of these isolates appeared susceptible to the extract. The inhibiting effect of the extract was also tested by the modified broth-dilution method on the most typical isolate (Aspergillus spp.). In this experiment, in one ml of the nutritious broth, 40µl of 3% solution of polysaccharides in water killed 10,000 fungal spores in 6 hours. The inhibiting effect was not connected to the acidity or osmotic effect of Sphagnum polysaccharides. As an example of the application of Sphagnum polysaccharides in art conservation, they were added as preservative agents to conservation waxes. After three weeks of exposure of microcrystalline wax to test fungi (Aspergillus spp.), 44% of wax was consumed. When, however, ~ 0.1% (w/w) of Sphagnum extract was mixed with wax, the weight loss of wax was only 4% in the same time interval. On the basis of this study it was concluded that Sphagnum moss and Sphagnum products can be recommended for use in art conservation as antifungal agents.