Dissertação
Atividade do óleo de Cymbopogon flexuosus livre e nanoestruturado frente a micobactérias de crescimento rápido
Fecha
2018-02-28Autor
Rossi, Grazielle Guidolin
Institución
Resumen
Rapidly Growing Mycobacteria (RGM) are emerging pathogens responsible for various
human infections, although they are often considered only as contaminants or colonizers. The
formation of biofilms by these microorganisms causes great concern for public health, due to
its greater pathogenicity in humans and antimicrobial resistance. Microbial cells within the
biofilm are protected by an autoproduced polymer matrix that delays the diffusion of
antimicrobials, preventing the drug from penetrating the deeper layers and having its effective
action. Thus, it is important to seek effective alternatives against the formation of biofilms. In
this sense, the use of biological products as well as the use of nanostructures have been
studied for the control of formation and development of biofilms. This work had as main
objective to evaluate the action of the essential oil (EO) of Cymbopogon flexuosus free and in
nanoemulsion on strains of RGM, in planktonic and sessile forms. EO was chemically
characterized. The nanoemulsion obtained by the homogenization method under high stirring
was characterized for its stability, surface charge and particle size. The assays of Minimum
Inhibitory Concentration (MIC) and time-kill curve were determined against standard strains
of RGM Mycobacterium abscessus (ATCC 19977), Mycobacterium fortuitum (ATCC 6841)
and Mycobacterium massiliense (ATCC 48898). The ability of the oil and nanoemulsion to
inhibit biofilm formation and to destroy it was evaluated by semi-quantitative macro
technique. In the susceptibility test of the microorganisms in planktonic form, the
nanoemulsion presented higher microbial activity, with MIC values lower than those
presented by free EO. However, the free EO had bactericidal action, while the nanostructure
had only bacteriostatic action. In the activity evaluation against RGM biofilms, both were
efficient in the destruction of the biofilm already formed, while only the free oil inhibited the
formation of mycobacterial biofilm. The results of this dissertation impact on the discovery of
a new pharmacological formulation, capable of enhancing the effects of EO and impairing the
formation of biofilms. In addition, this work stimulates the research in methodologies that aim
to clarify the influence exerted by the EO and the nanoemulsion on the genetic and
physiological factors associated with the biofilms formation.