Research Article | 01 May 2026

Microencapsulated Syzygium aromaticum essential oil enhances β-lactam efficacy against multidrug-resistant Staphylococcus aureus

Ellem Cristina Gomes Damascena1 ORCID , Eliane Macedo Sobrinho Santos2 ORCID , Carolina Magalhães Caires Carvalho1 ORCID , Charles Martins Aguilar1 ORCID , Cintya Neves de Souza1 ORCID , Francine Souza Alves da Fonseca1 ORCID , Ivan Pires De Oliveira1 ORCID , Adriana Fróes Do Nascimento Souto1, Hércules Otacílio Santos2 ORCID , and Anna Christina de Almeida1 ORCID Show more

1. Institute of Agricultural Sciences, Federal University of Minas Gerais, Montes Claros, Minas Gerais, Brazil.

2. Campus Araçuaí, Federal Institute of Northern Minas Gerais, Araçuaí, Minas Gerais, Brazil.

Corresponding author: Anna Christina de Almeida (aca2006@ica.ufmg.br)

Received: 2025-07-04, , Accepted: 03-12-2025 Published: 2026-05-01

INTERNATIONAL JOURNAL OF ONE HEALTH | pg no. 106-119 | Vol. 12, Issue 1 | DOI: 10.14202/IJOH.2026.106-119
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Abstract

          
Background and Aim: Antimicrobial resistance (AMR) is a major One Health concern, especially in dairy production systems where multidrug-resistant (MDR) Staphylococcus aureus limits mastitis control. Essential oils (EOs), such as Syzygium aromaticum EO, possess strong antimicrobial properties, but their volatility restricts stability. Microencapsulation enhances EO stability and functional performance. This study aimed to evaluate the antimicrobial effect of microencapsulated S. aromaticum EO (OESAM) combined with β-lactam antibiotics against MDR S. aureus. Additionally, bioinformatic analysis was used to explore the potential role of whey protein isolate (WPI) used in the microcapsule wall material in modulating antimicrobial action.
Materials and Methods: OESAM was prepared via complex coacervation using WPI and gum arabic as wall materials. Ten MDR S. aureus isolates from bovine mastitis were tested for minimum inhibitory concentrations (MICs) of OESAM, oxacillin, and meropenem using broth microdilution. Synergy was evaluated using the Checkerboard method and interpreted through the fractional inhibitory concentration index (FICI). A protein–protein interaction network was generated in STRING database to investigate molecular pathways potentially affected by amino acids in WPI.
Results: Microencapsulation produced stable microcapsules with a yield of 39.11%. The addition of OESAM significantly reduced the MICs of oxacillin and meropenem (p < 0.05), resulting in antimicrobial dose reductions of up to 2.7-fold. Synergistic and additive effects predominated among the isolates. These outcomes were further supported by their FICI values, which confirmed potentiation between OESAM and β-lactams. Bioinformatic analysis identified three major functional clusters: tryptophan biosynthesis, siderophore biosynthesis, and phosphorelay signal transduction, suggesting that amino acids present in WPI may interfere with metabolic and regulatory pathways of S. aureus, enhancing antimicrobial effectiveness.
Conclusion: OESAM substantially enhances β-lactam efficacy against MDR S. aureus, offering a promising strategy for reducing antimicrobial doses and combating resistance in veterinary practice. Microencapsulation improves EO stability and enables controlled-release, thereby enhancing antimicrobial activity. Further in vivo validation, toxicity assessment, and formulation development are recommended to facilitate practical applications in mastitis control and broader AMR mitigation.

         
Keywords: antimicrobial resistance, Staphylococcus aureus, fractional inhibitory concentration index, mastitis, microencapsulation, One Health, Synergy, Syzygium aromaticum, whey protein isolate.