Atividade antibacteriana e antibiofilme da Lippia grata frente a isolados clínicos de Pseudomonas aeruginosa
In the search for new possibilities of control against biofilms, studies involving the medical use of natural products have grown considerably in recent years, becoming a relevant field of research. Thus, natural antimicrobials present as an effective and economical alternative and their antimicr...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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Brasil
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/28269 |
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| Resumo: | In the search for new possibilities of control against biofilms, studies involving the
medical use of natural products have grown considerably in recent years, becoming a
relevant field of research. Thus, natural antimicrobials present as an effective and
economical alternative and their antimicrobial activity has already been proven in several
studies carried out in countries that have a diversified flora, such as Brazil. Motivated by
the search for new therapeutic strategies and considering the increasing bacterial
resistance, this work had as objective to evaluate the antibacterial activity and antibiofilm
of the extract and essential oil of Lippia grata against clinical isolates of Pseudomonas
aeruginosa. For this purpose, 44 P. aeruginosa isolates from different clinical samples
were used. The essential oil was extracted by hydrodistillation process and characterized
by gas chromatography associated with mass spectrometry. The antimicrobial
susceptibility profile was evaluated using the Kirby-Bauer technique and the cut off points
were established according to the Clinical and Laboratory Standards Institute (CLSI)
guidelines. The antibacterial activity of the extract and essential oil was evaluated by the
microdilution technique in broth, in which the MIC’s were determined using 2,3,5-
triphenyltetrazolium chloride (CTT) as a bacterial metabolism developer and the MBC’s
by means of growth analysis of the content of the few in Mueller-Hinton agar. The
determination of biofilm formation was performed using violet crystal and based on the
optical density produced by biofilms, the strains were classified as non-producing, weak
producing, moderate producing and strong producing. The antibiofilm activity of the plant
extract of Lippia grata was evaluated in the 25 isolates of Pseudomonas aeruginosa that
had a strong or moderate Biofilm production. In the chemical characterization of L. grata
essential oil, four main components were identified: carvacrol (51.4%) as major
constituent, thymol (15.6%), ρ-cymene (12.2%) and γ-terpinene (4%). Among the
antimicrobials tested, aztreonam showed the highest percentage of resistance (47.85),
followed by imipenem and levofloxacin, both with 41.0%, meropenem (36.4%),
piperacillin/tazobactam (35.0%), ceftazidime (34.1%), ciprofloxacin (31.9%) cefepime
(29.6%) and gentamicin (20.5%). The L. grata extract showed antimicrobial activity in
100% of the isolates tested at 50 mg / mL (MIC90 and MBC90). The concentration of 25
mg / mL (MIC50) showed inhibitory activity in 56.8% of the isolates and bactericidal
activity in 43.1% of the isolates. The essential oil of L. grata presented antimicrobial
activity in 100% of the tested isolates in the concentrations between 50 mg/mL and 6,25
mg/mL (MIC90). Concentrations of 3.12 mg/mL (MIC50) and 1.56 mg/mL showed
inhibitory activity in 70.4% and 27.2% of the isolates, respectively. None of the
concentrations tested for essential oil presented bactericidal activity on the tested
isolates. Regarding biofilm production, 18 (40.9%) isolates were classified as poor biofilm
producers, 18 (40.9%) as moderate producers, 7 (15.9%) as strong producers and only
1 (2.2%) did not produce biofilm. The 25 isolates with moderate or strong biofilm
production treated with the L. grata plant extract presented reduction in the formation
and consolidated biofilm. It is concluded with these results that L. grata presented
antimicrobial activity and antibiofilm, being configured as a promising alternative to
combat pathogenic microorganisms, particularly Pseudomonas aeruginosa. |
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