Phytochemical Composition and In Vitro Antibacterial Activity of the Essential Oil from Lippia grata Schauer (Verbenaceae) against Staphylococcus spp. from Caprine Mastitis

Staphylococcus spp. are the primary pathogens responsible for caprine mastitis. These bacteria can form biofilms, hindering treatment and compromising milk production. In this context, plant-based natural products derived from Lippia grata Schauer have emerged as a potential alternative for treatment. This study aimed to evaluate the antibacterial and antibiofilm properties of the essential oil (EO) of L. grata against Staphylococcus spp. isolated from caprine mastitis. The EO was obtained by hydrodistillation, and its chemical constituents were identified by gas chromatography coupled with mass spectrometry. Fourteen clinical isolates of Staphylococcus spp. and two standard strains were tested. Antibacterial activity was assessed using broth microdilution. Biofilm production and the interference capacity of the EO were evaluated using a microplate adherence assay. The EO of L. grata yielded 5.47%, with carvacrol (78%), thymol (7.1%), and p-cymene (3.16%) as the main constituents. It exhibited inhibitory and bactericidal effects at concentrations ranging from 256 to 512 μg mL^–1. All isolates formed biofilms, and the EO reduced biofilm formation in two isolates classified as moderate and strong producers. Additionally, it disrupted pre-established biofilms in all isolates. Therefore, the EO of L. grata exhibits antimicrobial and antibiofilm activities and represents a promising alternative for treating caprine mastitis, particularly in infections involving biofilm formation.