Resistência aos metais pesados em bactérias de importância médica isoladas de ambientes aquáticos no Brasil: uma revisão sistemática
Some heavy metals are essential for extremely important metabolic reactions and are also required as trace elements by various organisms. Others heavy metals have no biological role and are harmful, even at very low concentrations. Thus, bacteria that demonstrate the ability to survive toxic concent...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/43163 |
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| Resumo: | Some heavy metals are essential for extremely important metabolic reactions and are also required as trace elements by various organisms. Others heavy metals have no biological role and are harmful, even at very low concentrations. Thus, bacteria that demonstrate the ability to survive toxic concentrations of heavy metals were isolated from different sources. Many of these organisms have specific genetic mechanisms of resistance to these metals. In the environment, heavy metals may select such resistant variants in a manner similar to the selection of antibiotic resistant strains. Undoubtedly, the association of metal and antimicrobial resistance in a single bacterial strain is relatively common, since both resistance genes are often located in the same genetic elements. Thus, this work aims to discuss the resistance to heavy metals in bacteria of medical importance isolated from aquatic environments in Brazil, taking into account the isolation sites, the main heavy metals reported, the genes involved in the resistance, the genera and species and the main mechanisms of resistance present. This is a systematic literature review based upon specialized literature, through consultation of scientific articles, master's dissertations and doctoral thesis published and selected through search in the LILACS, SciELO and PubMed databases. After using the inclusion and exclusion criteria, five articles and a master's thesis were selected. Most of the publications (50%) were found in LILACS, with a higher prevalence for works carried out in the Southeast region (50%), and in freshwater environments (50%). Gram-negative bacteria were reported in all studies and the Escherichia coli species was the most prevalent (66.8%). Bacterial strains resistant to the following elements were also isolated: Cadmium (16.7%), Mercury (83.5%), Zinc (33.3%), Chromium (33.3%), Nickel (50%) and Silver (16.7%). The most prevalent resistance gene was merA (33.3%), which encodes the mercury reductase enzyme responsible for the conversion of the mercuric ion (Hg2+) to volatile metallic mercury. It was found that future studies on resistance to heavy metals in other aquatic environments still need to be carried out in Brazil, especially in environments that receive effluents from industries, hospitals, sewers, etc., due to the importance given to sanitary medical issues related to the disposal of contaminated effluents by heavy metals and the correlation between resistance to heavy metals and antimicrobials in aquatic bacteria. |
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