Própolis Brasileira Frente a Patógenos Associados às Infecções Neonatais: Abordagem Antibacteriana e Antiviral

Abstract

Neonatal infections represent a major global public health challenge due to high morbidity and mortality, particularly in neonatal intensive care units (NICUs). In this context, bacteria associated with sepsis and biofilm formation, opportunistic yeasts, and viruses such as Zika virus (ZIKV), which causes congenital infections and neurological alterations, stand out as clinically relevant pathogens. Accordingly, this study evaluated the in vitro antimicrobial, antibiofilm, anti–quorum sensing, and antiviral activities of the hydroethanolic extract of Brazilian red propolis (BRP) and the hydromethanolic extract of Caatinga green propolis (BGP-C) against microorganisms associated with neonatal infections. The strains evaluated included Staphylococcus epidermidis (ATCC 12228 and ATCC 14990), Staphylococcus aureus (ATCC 29213), Streptococcus pneumoniae (ATCC 6305), Streptococcus agalactiae (ATCC 13813), Streptococcus pyogenes (ATCC 19015), Enterococcus faecalis (ATCC 29212 and ATCC 51299), Listeria monocytogenes (ATCC 15313), Neisseria gonorrhoeae (ATCC 43069), Escherichia coli (ATCC BAA-198), Enterobacter cloacae (clinical isolate IAL 124), Candida albicans (ATCC 90028), and Zika virus (ZIKV), clinical isolate PE243. Antimicrobial activity was assessed by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC). Antibiofilm activity was analyzed by determining the minimum biofilm inhibitory concentration required to inhibit 50% of biofilm formation (MBIC₅₀) and the concentration that inhibited 50% of biofilm metabolic activity (IC₅₀). Morphological alterations and membrane integrity were investigated by scanning electron microscopy (SEM) and by staining with 4’,6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI). Interference with quorum sensing systems was investigated using the biosensor strain Chromobacterium violaceum CV026. Antiviral activity was evaluated in Vero E6 cells and, additionally, in human trophoblast BeWo cells. Both extracts exhibited activity against Gram-positive bacteria, with MIC values ranging from 6.25 to 400 µg/mL, highlighting Streptococcus pneumoniae and Streptococcus agalactiae (6.25 µg/mL) and Listeria monocytogenes (50 µg/mL), whereas no antibacterial activity was observed against Gram-negative species. For Candida albicans, both extracts exhibited MIC and MFC values of 200 µg/mL. BRP and BGP-C reduced biofilm biomass and metabolic activity, with evidence of impaired cellular integrity and no detectable interference with AHL-dependent quorum sensing. In antiviral assays, BRP and BGP-C reduced ZIKV infectivity by approximately 34% and 40%, respectively, under non-cytotoxic conditions, with dose-dependent antiviral activity observed in BeWo cells. Overall, these findings indicate that BRP and, particularly, BGP-C represent biologically relevant natural sources with in vitro activity against pathogens associated with neonatal infections.