Characterization and Evaluation of Layered Bi2WO6 Nanosheets as a New Antibacterial Agent.

Background: Pathogenic microorganisms are causing increasing cases of mortality and morbidity, along with alarming rates of ineffectiveness as a result of acquired antimicrobial resistance. Bi2WO6 showed good potential to be used as an antibacterial substance when exposed to visible light. This study demonstrates for the first time the dimension-dependent antibacterial activity of layered Bi2WO6 nanosheets. Materials and methods: The synthesized layered Bi2WO6 nanosheets were prepared by the hydrothermal method and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman and Fourier transform infrared spectroscopy (FTIR). Antibacterial and antibiotic-modulation activities were performed in triplicate by the microdilution method associated with visible light irradiation (LEDs). Results: Bi2WO6 nanosheets were effective against all types of bacteria tested, with MIC values of 256 µg/mL against Escherichia coli standard and resistant strains, and 256 µg/mL and 32 µg/mL against Staphylococcus aureus standard and resistant strains, respectively. Two-dimensional (2D) Bi2WO6 nanosheets showed antibacterial efficiency against both strains studied without the presence of light. Conclusions: Layered Bi2WO6 nanosheets revealed dimension-dependent antibacterial activity of the Bi2WO6 system.

Infections due to Phialemonium species: case report and review.

Abstract Infections caused by rarely encountered fungal pathogens have increased in recent decades. The present study describes a disseminated infection caused by Phialemonium curvatum, and reviews the literature in an effort to summarize prior experiences with this unusual pathogen. The clinical and microbiological characteristics of a new case due to Phialemonium are presented. The case is analysed with 19 other which have appeared in the literature since 1986. Ten cases were sporadic infections, while the others were associated with three small outbreaks. In all but our patient the skin's natural barrier was compromised (15/20 [75%]) and immunosuppression was a factor in the majority of cases (14/20 [70%]). Dissemination was noted in 83% (5/6) of the immunocompetent patients and in 57% (8/14) of immunocompromised patients. Endocarditis was the most frequent form of infection (8/20 [40%]). Blood cultures were positive in 92% (12/13) of those with disseminated disease. The mortality rate was 54% (7/13) among those with disseminated infections, but fatal outcomes were not observed in patients receiving treatment with itraconazole, voriconazole or posaconazole. The in vitro susceptibility of Phialemonium indicated a more consistent level of activity for voriconazole and posaconazole. Although infections usually occur when there is a breakdown in the skin the skin barrier or host defences are weakened, our case points out that infections due to Phialemonium species may occur in patients without these risk factors. The most frequent form of Phialemonium infections is endovascular, often with endocarditis and positive blood cultures, associated with high mortality rates. Treatment with the new triazoles is associated with improved survival.

¿Es necesario retrasar o suspender la cirugía en el caso de una posible bacteriuria asintomática? ¿Y una cirugía con implantes en ortopedia? / Is it necessary to delay or to put off surgery in the case of possible asymptomatic bacteriuria and orthopaedic surgery with implants?

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Autoxidation studies of extracellular hemoglobin of Glossoscolex paulistus at pH 9: cyanide and hydroxyl effect.

The complex oligomeric assembly of the hemoglobin subunits may influence the autoxidation rate. To understand this relation, the rate of autoxidation was studied at pH 9.0, where the Glossoscolex paulistus Hemoglobin (GpHb) dissociates. At alkaline pH, this hemoglobin is dissociated into monomers, trimers and tetramers, allowing the study of the integral protein and monomer subunit autoxidation on independent experiments. The autoxidation rate was evaluated in the presence and absence of cyanide (CN(-)), a strong field ligand to the ferric ion. The oxidation kinetic was monitored using the UV-vis absorption at 415 nm, and resulted in: i) bi-exponential kinetics for the whole hemoglobin (indicating a fast and a slow oxidative process) and ii) mono-exponential for the monomer (indicating a single process). To understand the specific characteristics of each autoxidation process, Arrhenius plots allowed the determination of the activation energy. The experimental results indicate for the whole hemoglobin in the absence of CN(-) an activation energy of 150 +/- 10 kJ mol(-1) for the fast and the slow processes. Under the same conditions the monomer displayed an activation energy of 160 +/- 10 kJ mol(-1), very close to the value obtained for the integral protein. The pseudo-second order rate constant for the whole protein autoxidation by CN(-) showed two different behaviors characterized by a rate constant k(CN1)' = 0.11 +/- 0.02 s(-1) mol(-1) L for CN(-) concentrations lower than 0.012 mol L(-1); and k(CN1)" = 0.76 +/- 0.04 s(-1) mol(-1) L at higher concentrations for the fast process, while the slow process remain constant with k(CN2) = 0.033 +/- 0.002 s(-1) mol(-1) L. The monomer has a characteristic rate constant of 0.041 +/- 0.002 s(-1) mol(-1) L for all cyanide concentrations. Comparing the results for the slow process of the whole hemoglobin and the oxidation of the monomer, it is possible to infer that the slow process has a strong contribution of the monomer in the whole hemoglobin kinetic. Moreover, as disulfide linkers sustain the trimer assembly, cooperativity may explain the higher kinetic constant for this subunit.

Abdomen agudo causado por Anisakis simplex / Acute abdomen due to Anisakis simplex

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Esquistosomiasis urinaria, a propósito de un caso importado en el Ecuador

Reportamos aquí un caso confirmado parasitológicamente de esquistosomiasis urinaria, causado por Schistosoma haematobium, en un hombre inglés de 29 años que posiblemente adquireió el parásito durante sus viajes a Egipto o Malawi hace tres meses. Hasta donde conocemos este es el primer caso confirmado en el país. Su importancia radica en el hecho de que el Ecuador es un país ecológicamente megadiverso por lo tanto turístico, rico en flora y fauna, siendo posible la introducción de enfermedades transmitidas por vectores desde otras altitudes. Además, este caso alerta la posibilidad de diagnósticos y manejos de patologías exóticas no conocidas en el Ecuador.