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Biofilmes polimicrobianos em águas ornamentais, potenciais riscos para a saúde pública e estratégias de prevenção
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Abstract(s)
As águas ornamentais podem funcionar como reservatórios de microrganismos patogénicos, constituindo um risco para a saúde pública. Este trabalho tem, como principal objetivo, avaliar a capacidade de produção de biofilmes in vitro, por bactérias potencialmente patogénicas para o Homem, isoladas de águas ornamentais.
As bactérias do estudo pertencem aos géneros Escherichia, Pseudomonas, Aeromonas e Klebsiella e foram caraterizadas segundo o crescimento a diferentes temperaturas, o tempo de geração, a temperatura ótima de crescimento e a capacidade de produção de biofilmes. A última foi determinada pelo método de cristal violeta, para bactérias isoladas ou em consórcios binários, de isolados do mesmo mês de colheita (co-existentes no ambiente) ou de meses distintos. Adicionalmente, foram comparados, qualitativa e estatisticamente, os resultados do método de cristal violeta (método convencional) e de impedância elétrica (método inovador), na determinação do efeito de Aeromonas spp., ou do seu sobrenadante, em biofilmes de Klebsiella pneumoniae.
A maioria dos isolados demonstrou crescimento a todas as temperaturas (5, 25, 37 e 45 ºC) e todos cresceram preferencialmente a 25 e 37 ºC, tendo apresentado tempos de geração inferiores a 88,8 minutos. Quanto à capacidade de formação de biofilme, 25 % dos isolados foram classificados como não produtores ou produtores fracos, 40 % como produtores moderados e 10 % como fortes produtores de biofilme. Em biofilmes binários, 90 % das interações entre bactérias co-existentes no ambiente foram competitivas, contudo, existiu uma maior competição em co-culturas de isolados de meses distintos de colheita. Na comparação entre os dois métodos, a análise qualitativa e a análise estatística apresentaram relações distintas (direta e inversa, respetivamente).
Em suma, estes resultados sugeriram que 75 % dos isolados apresentaram capacidade para produzir biofilmes in vitro, o que amplia o risco de infeções no Homem. É, assim, crucial, a tomada de medidas de controlo dos biofilmes no ambiente.
The ornamental waters can act as reservoirs of pathogenic microorganisms and constitute a risk to public health. The main objective of this work is to evaluate the capacity of in vitro biofilm production by bacteria potentially pathogenic to humans, isolated from ornamental waters. The bacteria of the study belong to the genera Escherichia, Pseudomonas, Aeromonas and Klebsiella and were characterized according to growth at different temperatures, generation time, the optimal temperature of growth and the ability of biofilm production. The latter was determined by the crystal violet method, for bacteria isolated or in binary consortia, from the same month of harvest (co-existing in the environment) or from different months. Adittionally, the results of the violet crystal method (conventional method) and the electrical impedance method (innovative method) were compared qualitatively and statistically for the determination of the effect of Aeromonas spp. or its supernatant on Klebsiella pneumoniae biofilms. Most of the isolates grew at all temperatures (5, 25, 37 and 45 °C) and all grew preferentially at 25 and 37 °C, with generation times of less than 88,8 minutes. As for the biofilm formation ability, 25 % of the isolates were classified as non-producers or weak producers, 40 % as moderate producers and 10 % as strong biofilm producers. In binary biofilms, 90 % of the interactions between bacteria co-existing in the environment were competitive, however, there was a higher competition in co-cultures of isolates from distinct months of harvest. In the comparison between the two methods, qualitative and statistical analysis showed distinct relationships (direct and inverse, respectively). In summary, these results suggested that 75 % of the isolates had the ability to produce biofilms in vitro, which can increases the risk of human infections. It is therefore crucial to take measures to control biofilms in the environment.
The ornamental waters can act as reservoirs of pathogenic microorganisms and constitute a risk to public health. The main objective of this work is to evaluate the capacity of in vitro biofilm production by bacteria potentially pathogenic to humans, isolated from ornamental waters. The bacteria of the study belong to the genera Escherichia, Pseudomonas, Aeromonas and Klebsiella and were characterized according to growth at different temperatures, generation time, the optimal temperature of growth and the ability of biofilm production. The latter was determined by the crystal violet method, for bacteria isolated or in binary consortia, from the same month of harvest (co-existing in the environment) or from different months. Adittionally, the results of the violet crystal method (conventional method) and the electrical impedance method (innovative method) were compared qualitatively and statistically for the determination of the effect of Aeromonas spp. or its supernatant on Klebsiella pneumoniae biofilms. Most of the isolates grew at all temperatures (5, 25, 37 and 45 °C) and all grew preferentially at 25 and 37 °C, with generation times of less than 88,8 minutes. As for the biofilm formation ability, 25 % of the isolates were classified as non-producers or weak producers, 40 % as moderate producers and 10 % as strong biofilm producers. In binary biofilms, 90 % of the interactions between bacteria co-existing in the environment were competitive, however, there was a higher competition in co-cultures of isolates from distinct months of harvest. In the comparison between the two methods, qualitative and statistical analysis showed distinct relationships (direct and inverse, respectively). In summary, these results suggested that 75 % of the isolates had the ability to produce biofilms in vitro, which can increases the risk of human infections. It is therefore crucial to take measures to control biofilms in the environment.
Description
Dissertação de mestrado em Engenharia do Ambiente (Engenharia Sanitária), apresentada à Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, 2019
Keywords
Águas Ornamentais Bactérias Patogénicas Biofilmes Infeções Saúde pública Ornamental Waters Água e Solo Biofilms Pathogenic Bacteria Infections Public health