## 1 Introduction  
Methicillin-resistant _Staphylococcus aureus_ (MRSA) infections and related clinical complications are on the increase. MRSA is a highly adaptive human pathogen causing benign skin and soft tissue infections, as well as life-threatening endocarditis and toxic shock syndrome (TSS) [1]. As a major nosocomial pathogen, it is implicated in both hospital- and community-acquired staphylococcal infections that are difficult to treat and control, due to a multifactorial combination of toxin-mediated virulence, invasiveness, and antibiotic resistance [2]. There has been a widespread increase in the resistance of _S. aureus_ to antibiotics over the past decade, and this has posed a great challenge for the development of effective therapeutics against this opportunistic pathogen [2].  
Antibiotic resistance in _Staphylococcus aureus_ is associated with staphylococcal cassette chromosome \(mcc\) (SCC\(mcc\)), known to encode for the \(mccA\) gene, which confers resistance to methicillin and other beta-lactam antibiotics [1]. The occurrence of resistance within and across different antibacterial classes has reinforced the urgent need for the discovery of new and potent compounds aiming at novel cellular metabolic functions hitherto not targeted by current antibacterial agents [2].  
According to a 2007 CDC report, the rate of mortality and morbidity due to MRSA in the U.S.A is on the increase. As such, the significance of this organism and its infections in relation to public health should not be underestimated [3]. Therefore, there is a significant need for more research into natural plant-based biodiversity to provide an alternative source of more efficacious antimicrobial secondary metabolites against this pathogen [2]. The current strategy for novel antibacterial discovery from natural products involves screening and expression analysis of promising targets against _S. aureus_. These targets encompass multifarious functionalities, including fatty acid metabolism, peptidoglycan and protein biosynthesis, cell division, DNA replication, and biosynthesis [4].  
Plants and plant-derived natural products are sources of secondary metabolites such as terpenoids, pentacyclic triterpenoids, flavonoids, and glycosides that have shown promising anti-staphylococcal activities [2, 5, 6, 7, 8]. Eugenol, a phenylpropanol, is found abundantly in the essential oils of species such as _Syzygium aromaticum_, _Cinnamomv zylanicum_, _Myristia fragrans_, _Ocimum basilicum_, _Illicium verum_, _Melissa officinalis_, _Anethum gravelens_, and _Laurus noblils_[9]. Eugenol is used in perfumes, flavourings, essential oils, and in medicines as a local antiseptic and anaesthetic. Previous studies have shown that eugenol has antimicrobial, antioxidant, anti-inflammatory, anti-carminative, and antispasmodic activities, and kills certain human colon cancer cell lines in vitro [10]. Similar studies on other plant-derived compounds showing anti-staphylococcal activities have been reported. In a preliminary study, betulinaldehyde has been reported to exhibit antibacterial activity against _S. aureus_, with an MIC value of 512 mg/mL. This compound potentiates the activity of the cell wall inhibitors methicillin, vancomycin [11], berberine chloride [12], cryptotanshinone [13], and rhein [14].  
Therefore, this study had the objective of ascertaining the transcriptional profile of genes expressed due to exposure of MRSA to subinhibitory concentrations of eugenol, and of fully understanding its possible mechanisms of action. Additionally, the genes upregulated when challenged with eugenol may also be explored as potential novel drug targets for the development of other therapeutics that synergise with eugenol in combating MRSA infections.