RESUMEN
Bacteria are an old concern to human health, as they are responsible for nosocomial infections, and the number of antibiotic-resistant microorganisms keeps growing. Copper is known for its intrinsic biocidal properties, and therefore, it is a promising material to combat infections when added to surfaces. However, its biocidal properties in the presence of light illumination have not been fully explored, especially regarding the use of microsized particles since nanoparticles have taken over all fields of research and subjugated microparticles despite them being abundant and less expensive. Thus, the present work studied the bactericidal properties of metallic copper particles, in microscale (CuMPs) and nanoscale (CuNPs), in the absence of light and under white LED light illumination. The minimum bactericidal concentration (MBC) of CuMPs against Staphylococcus aureus that achieved a 6-log reduction was 5.0 and 2.5 mg mL-1 for assays conducted in the absence of light and under light illumination, respectively. Similar behavior was observed against Escherichia coli. The bactericidal activity under illumination provided a percentage increase in log reduction values of 65.2% for S. aureus and 166.7% for E. coli when compared to the assays under dark. This assay reproduced the testing CuNPs, which showed superior bactericidal activity since the concentration of 2.5 mg mL-1 promoted a 6-log reduction of both bacteria even under dark. Its superior bactericidal activity, which overcame the effect of illumination, was expected once the nanoscale facilitated the interaction of copper within the surface of bacteria. The results from MBC were supported by fluorescence microscopy and atomic absorption spectroscopy. Therefore, CuMPs and CuNPs proved to have size- and dose-dependent biocidal activity. However, we have shown that CuMPs photoactivity is competitive compared to that of CuNPs, allowing their application as a self-cleaning material for disinfection processes assisted by conventional light sources without additives to contain the spread of pathogens.
Asunto(s)
Cobre , Staphylococcus aureus , Humanos , Cobre/farmacología , Cobre/química , Escherichia coli , Iluminación , Antibacterianos/farmacología , Antibacterianos/química , BacteriasRESUMEN
OBJETIVO: O estudo descreve a mortalidade por acidente de trabalho em Mato Grosso do Sul no ano de 2004. MÉTODO: Foi realizada análise de dados secundários das Declarações de Óbitos registradas em 2004. Do total de registros, foram identificados 88 como acidentes de trabalho e 57 óbitos sugestivos. Foram observadas as variáveis socio-demográficas, atividades econômicas e distribuição espacial. RESULTADOS: Constatou-se predomínio dos óbitos na população masculina, jovem, branca e com baixa escolaridade. Entre as principais ocupações atingidas está a dos motoristas, trabalhadores rurais e da construção civil. A maior ocorrência de registros foi em Dourados e Campo Grande. Os óbitos de trabalhadores no estado têm ocorrência similar ao do país em geral. CONCLUSÕES: Foram notificados apenas acidentes típicos, não houve registro de mortes ocorridas por doenças relacionadas ao trabalho que poderiam ter o campo correspondente preenchido. Recomenda-se a alteração dos termos do atestado de óbito substituindo o texto atual "acidente de trabalho" por "óbitos relacionados ao trabalho" de modo a introduzir no registro de óbito também as mortes resultantes de doenças do trabalho.
OBJECTIVE: This study describes mortalities due to work accidents in Mato Grosso do Sul State, using death certificates for 2004. METHOD: Of the total registered, 88 were identified as work accidents and 57 were suggestive of this fact. Socio-demographic aspects, economic activities and spatial distribution were observed as variables. RESULTS: It was found that the mortalities were predominantly in the population of young, white males of little schooling. Among the principal activities involved are motorists, rural, and civil construction workers. The accidents occurred mainly in the cities of Dourados and Campo Grande. CONCLUSIONS: It was concluded that in this State the mortality of workers is similar to that of the country: under-registration is important, and only typical accidents were notified. It is recommended that an alteration be made in the terms of the death certificate, substituting the present term "work accident" with death related to work so as to introduce in the register those deaths resulting from diseases related to work.