The growing resistance to conventional antimicrobials represents a global public health challenge, encouraging the search for effective and safe therapies. In this context, essential oils have stood out due to their antimicrobial activity, with reduced microbial resistance during their use against pathogens. This study aimed to evaluate the antimicrobial activity of Cordia verbenacea essential oil (EO) against clinically relevant pathogens.

The antimicrobial activity was assessed through Minimum Inhibitory Concentration (MIC) and Minimum Microbicidal Concentration (MMC) assays of the EO. The microbial strains included Acinetobacter baumannii (ATCC 19606); Candida albicans (INCQS 40175); Candida tropicalis (ATCC 750); Enterococcus faecalis (ATCC 51299); Enterococcus faecium (ATCC 6569); Klebsiella pneumoniae (ATCC 700603 and BAA 2814); Pseudomonas aeruginosa(INCQS 2742); Staphylococcus aureus (ATCC 29213 and ATCC 33591); Streptococcus mutans (ATCC 25175); Streptococcus oralis (ATCC 10557). MIC and MMC values were determined by the broth microdilution method in Mueller-Hinton broth (MH), following CLSI (2022) guidelines, with visual evaluation of microbial growth and confirmation of microbicidal activity on Brain Heart Infusion (BHI) agar. Tested concentrations ranged from 30 to 0.23 mg/mL, and bacterial and fungal inocula were standardized by McFarland scale at 0.5 × 10⁵ CFU/well and 0.5 × 10³ CFU/well, respectively, with incubation under conditions specific for each microorganism.

After MIC testing, it was observed that the EO showed inhibitory activity at 30 mg/mL for S. aureus (ATCC 33591), 25 ± 8.66 mg/mL for E. faecium, 20 ± 8.66 mg/mL for A. baumannii and C. tropicalis, 15 mg/mL for C. albicansand S. aureus (ATCC 29213), 15 ± 7.5 mg/mL for E. faecalis, 0.5 ± 0.42 mg/mL for S. mutans, and greater than 30 mg/mL for the remaining strains. The MMC assay showed that its activity was microbiostatic.

The EO demonstrated inhibitory activity at concentrations ranging from 30 to 0.5 mg/mL against the tested microorganisms, but no activity against K. pneumoniae and P. aeruginosa at the tested concentrations. Thus, EO represents a promising natural alternative for the control of clinically relevant pathogens, especially in light of the advance of microbial resistance.