Brazilian Propolis in the Context of Pathogens Associated with Neonatal Infections: An Antibacterial and Antiviral...

Neonatal infections remain a major global health challenge because of antimicrobial resistance, biofilm-associated persistence, and limited antiviral therapies. This study evaluated the antimicrobial, antibiofilm, in vivo efficacy, and antiviral activities of Brazilian red propolis (BRP) and Brazilian green propolis from the "Caatinga" biome (BGP-C) against pathogens associated with neonatal infections. Antimicrobial activity was determined by broth microdilution, whereas antibiofilm activity was assessed through biofilm biomass and metabolic activity inhibition and structural alterations were evaluated by fluorescence microscopy, and scanning electron microscopy. In vivo efficacy was assessed in a Caenorhabditis elegans infection model, and antiviral activity was investigated against Zika virus (ZIKV, PE243 strain). Both extracts exhibited antibacterial activity, mainly against Gram-positive bacteria, with minimum inhibitory concentrations of 6.25-400 µg/mL and minimum bactericidal concentrations of 25 to >400 µg/mL. MBIC₅₀ and IC₅₀ values ranged from 1.56-400 µg/mL and 0.64-163 µg/mL, respectively. Microscopy findings suggested reduced cell viability and compromised membrane integrity, together with biofilm disorganization. BRP consistently increased nematode survival across the infection models in which it was tested, whereas BGP-C showed no consistent protective effect. Under non-cytotoxic conditions, BRP and BGP-C reduced ZIKV infectivity by approximately 34% and 40%, respectively. These findings support the antimicrobial and antiviral potential of both extracts, while BRP demonstrated more consistent in vivo efficacy.