RESUMO
The search for coatings that extend the useful life of biomedical devices has been of great interest, and titanium has been of great relevance due to its innocuousness and low reactivity. This study contributes to the investigation of Ti/Ag films in different configurations (monolayer and multilayer) deposited by magnetron sputtering. The sessile droplet technique was applied to study wettability; greater film penetrability was obtained when Ag is the external layer, conferring high efficiency in cell adhesion. The morphological properties were characterized by SEM, which showed porous nuclei on the surface in the Ag coating and crystals embedded in the Ti film. The structural properties were studied by XRD, revealing the presence of TiO2 in the anatase crystalline phase in a proportion of 49.9% and the formation of a silver cubic network centered on the faces. Tafel polarization curves demonstrated improvements in the corrosion current densities of Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti and Ti/Ag compared to the Ag coating, with values of 0.1749, 0.4802, and 2.044 nA.m-2, respectively. Antimicrobial activity was evaluated against the bacteria Pseudomonas aeruginosa and Bacillus subtilis and the yeasts Candida krusei and Candida albicans, revealing that the Ti/Ag and Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti coatings exhibit promise in biomedical material applications.
Assuntos
Materiais Revestidos Biocompatíveis/química , Prata/farmacologia , Titânio/farmacologia , Molhabilidade/efeitos dos fármacos , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/patogenicidade , Candida/efeitos dos fármacos , Candida/patogenicidade , Materiais Revestidos Biocompatíveis/farmacologia , Humanos , Teste de Materiais , Pichia/efeitos dos fármacos , Pichia/patogenicidade , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/patogenicidade , Prata/química , Propriedades de Superfície , Titânio/químicaRESUMO
The assertion made by Wu et al. that aromaticity may have considerable implications for molecular design motivated us to use nucleus-independent chemical shifts (NICS) as an aromaticity criterion to evaluate the antifungal activity of two series of indol-4-ones. A linear regression analysis of NICS and antifungal activity showed that both tested variables were significantly related (p < 0.05); when aromaticity increased, the antifungal activity decreased for series I and increased for series II. To verify the validity of the obtained equations, a new set of 44 benzofuran-4-ones was designed by replacing the nitrogen atom of the five-membered ring with oxygen in indol-4-ones. The NICS(0) and NICS(1) of benzofuran-4-ones were calculated and used to predict their biological activities using the previous equations. A set of 10 benzofuran-4-ones was synthesized and tested in eight human pathogenic fungi, showing the validity of the equations. The minimum inhibitory concentration (MIC) in yeasts was 31.25 µg·mL-1 for Candida glabrata, Candida krusei and Candida guilliermondii with compounds 15-32, 15-15 and 15-1. The MIC for filamentous fungi was 1.95 µg·mL-1 for Aspergillus niger for compounds 15-1, 15-33 and 15-34. The results obtained support the use of NICS in the molecular design of compounds with antifungal activity.
Assuntos
Antifúngicos/farmacologia , Benzofuranos/farmacologia , Fungos/efeitos dos fármacos , Antifúngicos/química , Aspergillus niger/efeitos dos fármacos , Aspergillus niger/patogenicidade , Benzofuranos/química , Candida/efeitos dos fármacos , Candida/patogenicidade , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Pichia/efeitos dos fármacos , Pichia/patogenicidade , Hidrocarbonetos Policíclicos Aromáticos/química , Hidrocarbonetos Policíclicos Aromáticos/farmacologiaRESUMO
Yeasts belonging to the genus Pichia were isolated from glucose syrup samples. Yeasts were identified as P. anomala ( it is now Wickerhamomyces anomala) and P. guilliermondii. These strains did not metabolize the nutritive preservatives, potassium sorbate or sodium benzoate when these were used as the single carbon source. P. anomala grew in culture media containing up to 1200 mg/L of both preservatives. Critical temperature and time of exposure for its inactivation were 60 °C and 3 min, respectively. P. guilliermondii grew in media containing up to 1400 mg/L of both preservatives. Critical temperature and time for inactivation of this Pichia were 80 °C and 2 min. This strain was able to grow in a wide range of temperatures (5 to 30 °C), pH (2.5 to 5.5) and glucose concentrations (200 to 800 g/L). At 5 °C and 800 g/L glucose (osmotic pressure, 0.110 atm), P.guilliermndii grew poorly, with no cell death because of its ability to sporulate. We determined that P. guilliermondii is a potentially contaminating yeast able to develop in a variety of foods, especially those with low pH or with high sugar concentrations (glucose above 400g/L) such as refreshments, juices, syrups and confected fruits and it is resistant to both food preservatives and low temperatures (5°C).
De muestras de jarabe de glucosa fueron aisladas levaduras que pertenecen al género Pichia. Estas fueron identificadas como P.anomala (actualmente Wickerhamomyces anomala) y P. guilliermondii, ambas cepas no metabolizan los conservantes alimenticios, sorbato de potasio o benzoato de sodio, al ser usados como única fuente de carbono. P. anomala desarrolló en medios de cultivo que contenían hasta 1200 mg/L de ambos conservantes. La temperatura y el tiempo crítico de exposición para su inactivación fueron 60 °C y 3 min, respectivamente. P.guilliermondii desarrolló en medios que contienen hasta 1400 mg/l de ambos conservantes. La tº y el tiempo crítico de inactivación fueron 80 °C y 2 min. Esta cepa fue capaz de desarrollar en un amplio rango de temperaturas (5 a 30 °C), pH (2,5 a 5,5) y concentraciones de glucosa (200 a 800 g/L). A 5 °C y glucosa 800 g/L (presión osmótica, 0,110 atm), P. guilliermondii desarrolló pobremente sin que se produzca la muerte celular debido a su capacidad de esporular. Se determinó que P. guilliermondii, es una levadura potencialmente contaminante que puede desarrollarse en una variedad de alimentos, especialmente aquellos con bajo pH o altas concentraciones de azúcar (glucosa, > 400 g/L) como en gaseosas, jugos, jarabes y frutas confitadas, y es resistente a ambos conservantes y bajas tº (5°C).
Assuntos
Níveis Máximos Permitidos , Pichia/isolamento & purificação , Pichia/crescimento & desenvolvimento , Pichia/patogenicidade , Temperatura , LevedurasRESUMO
Pichia anomala es una levadura oportunista emergente, ocasionalmente responsable de graves infecciones hospitalarias en lactantes y niños inmunocomprometidos. En este trabajo describimos la presencia de P. anomala en sangre de 13 niños cateterizados en el Hospital del Niño Jesús de Tucumán (Argentina), en un periodo de 5 años. Estos representan el 9,71 por ciento de 350 muestras de sangre de pacientes pediátricos internados en unidades de terapia intermedia, cuidados intensivos y sala de oncología. P. anomala fue tan frecuente como Candida tropicalis en los hemocultivos examinados en el período en estudio. Teniendo en cuenta que la manipulación frecuente de catéteres y su uso prolongado favorecen el desarrollo de fungemia causadas por esta levadura, creemos imprescindible realizar mayores estudios epidemiológicos para determinar su real importancia clínica.
Pichia anomala is an opportunistic emerging yeast, occasionally responsible for serious hospitalinfections both in lactating babies and in immunocompromised children. We describe herein the presence of P. anomala in the blood of thirteen catherized children which was detected at the Hospital del Niño Jesús de Tucumán (Argentina), within a 5-year period. The above cases represent 9.71 percent out of the 350 blood samplescollected from pediatric patients admitted in intermediate therapy, intensive care and oncology wards.P. anomala was as frequent as Candida tropicalis in the blood cultures under examination during the period ofstudy.Considering that repeated catheter manipulation and prolonged use favour the development of fungaemiacaused by this yeast, we think it is most necessary to carry out further epidemiological studies to assess itsreal clinical significance.
Assuntos
Humanos , Masculino , Feminino , Lactente , Pré-Escolar , Criança , Antifúngicos , Hospedeiro Imunocomprometido , Pichia/isolamento & purificação , Pichia/patogenicidade , Argentina , Fungemia , Fungos/isolamento & purificação , Fungos/classificação , Fungos/patogenicidade , Controle de InfecçõesRESUMO
OBJECTIVE: To report an outbreak of Pichia anomala fungemia that occurred in a Brazilian pediatric intensive care unit (ICU) from October 2002 to January 2004. DESIGN: Unmatched case-control study. METHODS: We randomly selected four control-patients for each case-patient from a list of all patients admitted to the ICU for at least 48 hours during the outbreak. A second control group was composed of all consecutive patients with nosocomial candidemia in the ICU during the outbreak. An environmental study was performed, and genetic relatedness among the clinical isolates was characterized by randomly amplified polymorphic DNA assay. RESULTS: During the study period, 1,046 children were admitted to the pediatric ICU, 17 of whom developed P. anomala fungemia (attack rate, 1.6%). The median age was 1.1 years, and the main underlying conditions were congenital malformations (35.3%) and neoplastic diseases (11.8%). The overall mortality rate was 41.2%. Two patients received no antifungal treatment; all of the others were treated with amphotericin B. On multivariate analysis, only the presence of a central venous catheter was significantly associated with P. anomala fungemia. The yeast was not found on healthcare workers' hands or in the environment. Molecular studies showed that the outbreak was caused by a single strain. The distribution of risk factors was similar between patients with P. anomala fungemia and control-patients with candidemia. CONCLUSIONS: This study highlights the importance of P. anomala as an emerging nosocomial fungal pathogen. Patients with P. anomala fungemia seem to have risk factors in common with those who have candidemia.
Assuntos
Doenças Transmissíveis Emergentes/epidemiologia , Infecção Hospitalar/epidemiologia , Surtos de Doenças/estatística & dados numéricos , Fungemia/epidemiologia , Unidades de Terapia Intensiva Pediátrica , Pichia , Distribuição por Idade , Anfotericina B/uso terapêutico , Antifúngicos/uso terapêutico , Brasil/epidemiologia , Candidíase/epidemiologia , Candidíase/microbiologia , Estudos de Casos e Controles , Cateterismo Venoso Central/efeitos adversos , Doenças Transmissíveis Emergentes/microbiologia , Infecção Hospitalar/microbiologia , DNA Fúngico/análise , DNA Fúngico/genética , Feminino , Fungemia/microbiologia , Mortalidade Hospitalar , Humanos , Lactente , Masculino , Testes de Sensibilidade Microbiana , Análise Multivariada , Pichia/genética , Pichia/isolamento & purificação , Pichia/patogenicidade , Técnica de Amplificação ao Acaso de DNA Polimórfico , Fatores de Risco , Estações do AnoRESUMO
Systemic infections caused by opportunistic fungi have shown an increased frequency in the past 10 years, particularly in immunocompromised patients. Hansenula anomala is an ascosporogenous yeast of the Ascomycetes class found in the skin, throat, and digestive tract transient normal flora. This study was conducted to compare the pathogenicity of H. anomala and Candida albicans in a model of immunocompromised mice. Thirty-eight Swiss mice were divided into two groups as follows: 30 animals received an intraperitoneal (i.p.) injection of cyclophosphamide (200 mg/kg) four days before the induction of infection with H. anomala (1 x 10(6) yeasts/mL), and 8 animals received 100 mg/kg of cyclophosphamide at 3-day intervals during 3 weeks before inoculation of 1 x 10(7) yeasts/mL. All animals were treated with amoxicillin/clavulanic acid (40 mg/kg) four days before induction of infection. A group of mice inoculated with C. albicans (ATCC 64548) served as control. Tissue samples from the lung, spleen, liver, and kidney for histological and mycologic studies were obtained at necropsy. In each animal, the number of viable yeasts per gram of kidney was determined. The organs most frequently infected by H. anomala were the kidneys and the liver (20%), and the lung (10%). However, in conditions of sustained immunosuppression, H. anomala was found in 65.5% of the organs examined. It is concluded that in an experimental model of immunocompromised mice, the pathogenicity of H. anomala was low.