ABSTRACT

The increasing prevalence of multidrug-resistant (MDR) Staphylococcus aureus poses a significant threat to global health. This study investigated the antimicrobial activity of Rosmarinus officinalis (Rosemary) extracts against MDR S. aureus. The results showed that Rosemary extracts exhibited significant antimicrobial activity, with minimum inhibitory concentration (MIC) values ranging from 1.0-2.1 cm. The antimicrobial activity of Rosemary extracts was attributed to the presence of phytochemical compounds such as carnosic acid, rosmarinic acid, camphor, borneol, and bornyl acetate. These findings suggest that Rosemary extracts may be a useful adjunct to existing antibiotics in combating MDR S. aureus infections. Further research is needed to explore the potential clinical applications of Rosemary extracts as antimicrobial agents

CHAPTER ONE                                                   

INTRODUCTION

• Background

The global rise of antibiotic resistance particularly among multi-drug resistant (MDR) bacteria, poses a significant threat to public health, undermining the effectiveness of conventional antimicrobial therapies (WHO, 2014). The overuse and misuse of antibiotics have accelerated the development of MDR bacteria, making it challenging to treat infections effectively (CDC, 2020). Antibiotics are often prescribed unnecessarily or inappropriately, contributing to the selection and spread of resistant bacteria. MDR bacteria, defined as microorganism resistant to multiple classes of antibiotics, are rapidly diminishing the effectiveness of conventional antimicrobial treatments, leading to prolonged illness, increased mortality rates, and higher healthcare costs (Laxminarayan et al., 2013; Magiorakos et el., 2012). MDR bacteria possess complex mechanisms that enable them to evade the effects of antibiotics (Blair et al., 2015). These mechanisms include; Efflux pumps, enzymatic inactivation, target modification, and biofilm formation.

The increase prevalence of MDR bacteria presents a formidable challenge to modern healthcare systems worldwide. These organisms include, strains of Staphylococcus aureus (MRSA), Echerichia coli (ESBL-producing strains), Acinetobacter baumannii (carbapenem-resistant strains). Have developed mechanisms to resist multiple classes of antibiotics, rendering common infections difficult, if not impossible, to treat (Munita & Arias, 2016). The rise in MDR infections has been linked to factors such as overuse and misuse of antibiotics, as well as inadequate infection control practices (Blair et al., 2015). This situation necessitates the development of new antimicrobial strategies that can bypass current resistance mechanisms. The development of novel antimicrobial agents is crucial to combat the growing threat of MDR bacterial (Coates et al.,2011). Ideally, these agents should; target novel mechanisms by exploiting vulnerabilities in bacterial cells that have not been targeted by existing antibiotics. Be effective against MDR bacterial be demonstrating activity against bacterial that are resistant to multiple antibiotics and have a low risk of resistance development.

As the effectiveness of traditional antibiotics wanes, there is an urgent need to explore alternative therapeutic options, including plants based antimicrobials (Cragg & Newman, 2013). Plants have been used for centuries in traditional medicine to treat various ailments, and many have been found to possess antimicrobial properties. Plants derived antimicrobials have been a subject of interest in recent years due to their potential to provide novel solutions to the problem of antibiotic resistance (Cowan, 1999). Plants have evolved complex defense mechanisms to protect themselves against microbial pathogens, and many of these mechanisms involve the production of antimicrobial compounds. Among the many plants with reported medicinal properties, Rosmarinus officinalis L., commonly known as Rosemary, has gained considerable attention. Rosemary plant (Rosmarinus officinalis) is a medicinal plant that has been used for centuries to treat various ailments, including digestive issues, respiratory problems, and skin infections (Kamatou et al., 2013).

This aromatic evergreen shrub, belonging to the Lamiaceae family, is native to the Mediterranean region and has a long history of traditional use in various cultures for culinary, cosmetic, and medicinal purposes (Raskovic et al., 2011). The phytochemical composition of Rosemary plant is particularly noteworthy for its diverse array of bioactive compounds, including: Phenolic Diterpenes, Carnosic acid and carnosol as prominent phenolic diterpenes in Rosemary plant, known for their potent antioxidant and anti-inflammatory activities (Britic et al., 2015; Ozcan, 2008). Phenolic Acids; rosmarinic acid is a major phenolic acid found in rosemary plant and is recognized for its antioxidant, anti-inflammatory, and antiviral activities (Petersen & Simmonds, 2003). Essential Oils; rosemary essential oil is a complex mixture of volatile compounds, including 1.8-cineole, camphor, alpha-pinene, and beta-pinene (Dorman & Deans, 2000). Flavonoids; Rosemary also contains various flavonoids such as luteolin and apigenin, which contribute to its overall antioxidant and anti-inflammatory activities (De Sousa et al., 2015).

Rosemary has been reported to possess antimicrobial activity against a range of microorganisms, including bacteria, fungi, and viruses (Sahu et al., 2013). While some studies have shown that extracts and essential oils possess in vitro antibacterial activity against various bacterial pathogens including some MDR strains (de Oliveira et al., 2019; Daglia et al., 2019), nvestigating the pharmacological and antimicrobial activity of rosemary against MDR bacteria.

1.2.Problem Statement

MDR bacteria are microorganisms that have developed resistance to multiple classes of antibiotics, making infections difficult to treat (Magiorakos et al., 2012). These organisms are significant cause of morbidity and mortality globally, particularly in hospital settings (Laxminarayan et al., 2013). The mechanisms of resistance are varied and include enzymatic inactivation of antibiotic target sites, and increased efflux of drugs from bacterial cells (Blair et al., 2015). The growing prevalence of MDR bacteria emphasizes the urgent need for novel antimicrobial compounds with different mechanisms of action to tackle this crisis (Munita & Arias, 2013). This study therefore sought to investigate the pharmacological and antimicrobial properties of Rosmarinus officinalis (Rosemary plant) on MDR bacterial like Staphylococcus aureus.

1.3. Research Questions

1. What are the pharmacological properties of Rosmarinus officinalis?
2. Does Rosemarinus officinalis exhibit antimicrobial activity against MDR bacteria?
3. What is the Minimum Inhibitory Concentration (MIC) of Rosmarinus officinalis against MDR bacteria?

1.3. Research Objectives

1.3.1. General Objective

To investigat the antimicrobial properties of Rosmarinus officinalis (Rosemary plant) on MDR bacteria in vitro.

1.3.2. Specific Objectives

1. Rosemary extract preparation and culturing of MDR bacteria (Staphylococcus aureus).
2. To investigate the pharmacological and antimicrobial activity of Rosmarinus officinalis against MDR bacteria in vitro.
3. To determine the MIC of Rosmarinus officinalis against MDR.