Perfil de resistência e sensibilidade de cepas comerciais bacterianas e fúngicas utilizadas em ensaios laboratoriais de atividade antimicrobiana

Abstract

Microorganisms are microscopic beings and therefore cannot be seen with the naked eye. Bacteria, fungi, viruses, microscopic algae, and protozoa play a fundamental role in the life of the planet, since they act in the cycling of nutrients in the atmosphere, besides producing organic compounds of biotechnological importance. However, many microorganisms act as human and animal pathogens causing damage to the health of the population and economic losses. Thus, antimicrobial compounds have been used to combat diseases caused by these pathogens, but each microbial species responds differently to these substances, and increasingly resistant strains to currently available drugs have been observed. In this context, the present study aimed to analyze the resistance and sensitivity profile of commercial bacterial and fungal strains used in laboratory tests in the presence of commercially purchased antimicrobial substances. In addition, the antimicrobial activity of endophytic fungal metabolites isolated from Amazonian plants was evaluated against the strains that were resistant to commercially antimicrobials. Agar diffusion methodology was used to check the resistance and sensitivity profile of commercial bacterial and fungal strains against different commercial antimicrobials. Endophytic fungi deposited at the Microbiological Collection Center of UEA were cultivated in a liquid medium for metabolite production. After mycelium separation, the liquid medium was extracted with ethyl acetate. The fungal extracts were used in antimicrobial activity assays against the standard strains that proved to be resistant to at least three of the commercial antimicrobials. Ii was possible to observe that three pathogenic bacteria (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) and two pathogenic fungi (Candida albicans and Candida tropicalis) showed to be resistant against commercial drugs. The other microorganisms The tests with the extracts of endophytic fungi isolated from Amazonian plants Aspergillus niger MgF2, Phyllosticta fallopiae Ag2-5, Fusarium continuum Ag4-5B, Alternaria sp. C26, Aspergillus niger MgRE231, and Piper hispidum Ph174 did not show activity to inhibit the growth of the commercial-resistant strains. In our study, it was possible to know the resistance and sensitivity profile of the standard strains used in antimicrobial activity tests against commercial antimicrobials. Keywords: microbial resistance, antimicrobials, microorganisms.