Citation: Elangovan, S.; Mudgil, P. Antibacterial Properties of Eucalyptus globulus Essential Oil against MRSA: A Systematic Review. Antibiotics 2023, 12, 474. https://doi.org/10.3390/ antibiotics12030474 Academic Editor: Melissa M. Cadelis Received: 8 February 2023 Revised: 22 February 2023 Accepted: 24 February 2023 Published: 27 February 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). antibiotics Systematic Review Antibacterial Properties of Eucalyptus globulus Essential Oil against MRSA: A Systematic Review Shakthi Elangovan and Poonam Mudgil * School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia * Correspondence: p.mudgil@westernsydney.edu.au; Tel.: +61-2-46203945 Abstract: Antimicrobial resistance is a huge threat against the public health sphere and is a major cause of global mortality and morbidity. Antibiotic misuse and overuse have led to the development of many resistant bacterial strains. One particular bacterium of concern is methicillin-resistant Staphylococcus aureus (MRSA), which is the most common resistant bacteria in humans. Antibiotic development has been unable to keep up with the rapid evolution of antibiotic-resistant organisms, and there is an urgent need to identify alternative agents to combat this problem. The purpose of this systematic review is to explore the literature on the antibacterial properties of Eucalyptus globulus essential oil against MRSA. The articles used in this review were obtained through a systematic search of the literature across four databases, with the timeline being between 2002 and 2022. Twenty studies were included in this review, which used various methods to investigate the antibacterial properties of E. globulus essential oil, alone or in combination with other agents, against MRSA. The findings suggest that E. globulus essential oil has antibacterial properties against MRSA, which can be enhanced when used in combination with other agents, such as other essential oils and antibiotics. Keywords: methicillin-resistant Staphylococcus aureus; MRSA; Staphylococcus aureus; antibiotics; antimicrobial resistance; eucalyptus oil; eucalyptus essential oil; E. globulus essential oil 1. Introduction Antibiotic resistance is a phenomenon in which bacteria are able to evade antibiotics via various mechanisms, including neutralisation of the drug, excreting the drug, modifying structural components to prevent the drug from acting on the cell and DNA transfer between bacteria [1,2]. Drivers of this resistance include overuse and misuse of antibiotics in clinical and agricultural settings [1,3]. When antibiotics are used, they act on drug- sensitive bacteria, eradicating them and leaving behind resistant bacteria, which reproduce and proliferate [3]. Since the advent of modern antibiotics in the 1940s, bacteria have developed resistance to almost all available antibiotics and pose a huge threat to public health [3]. It is a major cause of global mortality and is classified by the World Health Organisation (WHO) as being in the top ten threats to global health [4]. Methicillin-resistant Staphylococcus aureus (MRSA) was first described in 1961 and, since then, it has become the most common resistant strain of bacteria in healthcare [2,5]. MRSA causes a wide range of infections, with the most common sites being the skin and subcutaneous tissue, followed by sites, including, but not limited to, the meninges, endocardium and bone [5,6]. The first three decades of MRSA cases were predominantly in those who had contact with hospitals, but in the 1990s, infections began to emerge in community settings in those that had no healthcare contact, presenting a major problem to the public health sphere. Management of MRSA depends on the specific disease and involves strict infection preven- tion methods and antibiotic administration. In the hospital setting, intravenous vancomycin is often the drug of choice, with daptomycin being a suitable alternative. However, cases of Antibiotics 2023, 12, 474. https://doi.org/10.3390/antibiotics12030474 https://www.mdpi.com/journal/antibiotics