ANTIMICROBIAL AND ANTIBIOFILM ACTIVITY OF COMBINED CHAMOMILE AND CASHEW EXTRACTS ON MULTI-RESISTANT STRAINS OF Pseudomonas aeruginosa

• Grant number: 25/03993-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: April 30, 2026
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Vanessa Marques Meccatti Domiciano
• Grantee: Pablo de Oliveira
• Host Institution: Instituto de Ciência e Tecnologia (ICT). Universidade Estadual Paulista (UNESP). Campus de São José dos Campos. São José dos Campos , SP, Brazil

Abstract

There is currently a high incidence of multidrug-resistant bacteria (MDRs) in hospital environments, a global alert situation. Among the critical priority bacteria listed by the WHO (World Health Organization) in 2024, Pseudomonas aeruginosa is in the second group, of high priority, for the development of new treatments. Among the treatment alternatives, phytotherapy has shown promising antimicrobial potential. Treatment alternatives are necessary, in which phytotherapy and the capacity for synergistic action between plants consist of an excellent strategy on the rise in modern pharmacology to slow down the process of microbial resistance. The objectives of the work will be: to obtain and perform phytochemical analysis of the hydroalcoholic extracts of chamomile (Matricaria recutita L.) and cashew (Anacardium occidentale L.); to analyze the antimicrobial activity of the isolated and combined extracts on planktonic cultures of multidrug-resistant P. aeruginosa; to evaluate the antibiofilm action of the combination of extracts, compared to chlorhexidine gluconate. For phytochemical analysis, the following will be evaluated: soluble solids content, antioxidant activity, quantification of total flavonoids and phenols and the chemical characterization of the extracts through High Performance Liquid Chromatography (HPLC). The antimicrobial activity will be analyzed by the broth microdilution test (CLSI M7-A9) to determine the minimum inhibitory concentration (MIC) and the minimum microbicidal concentration (MMC), with the combination being performed by the checkerboard method. The effective synergistic and/or additive concentrations will be analyzed in monotypic biofilms of P. aeruginosa in two methods: prevention and eradication, under combined treatment of extracts for a contact time of 5 and 30 minutes and the viability quantified by the colorimetric MTT test. The data will be analyzed by Anova one-way and Tukey or Kruskal Walis and Dunn considering the level of significance (p < 0.05), according to the normality test.