Salmonella enterica serovar Typhimurium (ST) remains a major infectious agent in the USA, with an increasing antibiotic resistance pattern, which requires the development of novel antimicrobials capable of controlling ST. Polyphenolic compounds found in plant extracts are strong candidates as alternative antimicrobials, particularly phenolic acids such as gallic acid (GA), protocatechuic acid (PA) and vanillic acid (VA). This study evaluates the effectiveness of these compounds in inhibiting ST growth while determining changes to the outer membrane through fluorescent dye uptake and scanning electron microscopy (SEM), in addition to measuring alterations to virulence genes with qRT-PCR. Results showed antimicrobial potential for all compounds, significantly inhibiting the detectable growth of ST. Fluorescent spectrophotometry and microscopy detected an increase in relative fluorescent intensity (RFI) and red-colored bacteria over time, suggesting membrane permeabilization. SEM revealed severe morphological defects at the polar ends of bacteria treated with GA and PA, while VA-treated bacteria were found to be mid-division. Relative gene expression showed significant downregulation in master regulator hilA and invH after GA and PA treatments, while fliC was upregulated in VA. Results suggest that GA, PA and VA have antimicrobial potential that warrants further research into their mechanism of action and the interactions that lead to ST death.

<p>La metritis, enfermedad que causa una baja fertilidad en alpacas fue caracterizada en 80 alpacas vacías. Lesiones histopatológicas del endometrio, cultivo de bacterias, niveles de opsoninas, y la efectividad del <em>Bacillus subtilis</em> como probiótico fue evaluado. La presencia de exudado en las glándulas endometriales, presencia de linfocitos, macrófagos, células plasmáticas, fibrocitos, fibroblastos y tejido periglandular a nivel estrato compacto indicaron una inflamación crónica. En los cultivos bacteriológicos se aislaron Arcanobacterium pyogenes. Inmunoglobulina G como indicador de opsonización fue 1576 mg/dL en alpacas metrìticas y 166 mg/dL en alpacas sanas (P&lt;0.05). Bacillus subtilis fue 90% eficiente en el tratamiento de metritis.</p><p> </p>