ABSTRACT

This study was to determine the bactericidal effects of Garlic (Allium sativum) on Staphylococcus aureus, Streptococcus spp. Escherichia coli and Salmonella spp. The fresh Garlic (Allium sativum), in bulbs forms were obtained from Ahieke Market. The test organisms used in this research consisted of two Gram-positive and two Gram-negative bacteria isolates obtained from stool, sputum samples, and skin swabs. The test organisms used included; Escherichia coli, Staphylococcus aureus, Salmonella species and Streptococcus species. Three (3) solvents (hot water, cold water and methanol) were used to get a comparative result. Agar well diffusion method was used to determine the bactericidal effects of the Garlic (Allium sativum) on the test organisms. The methanolic extract of Garlic (Allium sativum) was found to exhibit high degrees of antibacterial activities against the test isolates. This was shown by the clear zones of inhibition produced by the methanolic extract on the test microorganisms. The highest in-vitro antibacterial activity is 16mm which was exhibited by the methanolic extract at the highest concentration of 200mg/ml against Staphylococcus aureus followed by Salmonella species 14(200mg/ml), while no antibacterial activity (0.0mm) was exhibited by the Methanolic extract at the lowest concentration of 50mg/ml against all the test organisms. It was also observed in this study that the Garlic (Allium sativum) extract had both a bacteristatic and bactericidal activity when tested in vitro using methanolic preparation of garlic extract. Therefore, garlic may be used successfully for treating food poisoning causative agent like Staphylococcus aureus. It may be effective on other microbes on gram positive and gram-negative bacteria, so that further in vivo and in vitro studies are necessary. The standard antibiotics (Ciprofloxacin and Chloramphenicol) used as control inhibited the test bacteria and fungi respectively; it had higher inhibitory activity compared to the Garlic (Allium sativum) extracts. More importantly, there is need for detailed scientific study of traditional medical practices to ensure that valuable therapeutic knowledge of some plants is preserved and also to provide scientific evidence for their efficacies.

TABLE OF CONTENTS

Title Page     i

Certification iii

Dedication iv

Acknowledgement v

Table of Contents vi

List of Tables vii

Abstract ix

CHAPTER ONE

1.0 Introduction 1

1.1 Background of Study 1

1.2 Aim of Study 2

1.3 Specific Objectives 2

CHAPTER TWO

2.0 Literature Review 3

2.1 Brief Description of Garlic (Allium sativum) 3

2.2 Brief History of Garlic (Allium sativum) 3

2.3 Chemical Constituents of Garlic (Allium sativum) 4

2.4 Medicinal Values of Garlic (Allium sativum) 5

2.4.1 Treatment Cardiovascular Disease 5

2.4.2 Reduces High Blood Pressure/Hypertension 6

2.4.4 Natural Blood Thinner 6

2.4.5 Prevents Diabetes 7

2.5 Antimicrobial Properties of Garlic (Allium sativum) 7

2.5.1 Antiviral Effect 8

2.5.2 Antibacterial Effect 8

2.5.3 Adverse Effects of Garlic 9

2.6 Classification of Phytochemicals 9

2.6.1 Tannins 9

2.6.2 Flavonoids 10

2.6.3 Organic Acids 10

2.6.4 Phenols 10

2.6.5 Nitrogenous Compounds 10

2.6.6 Terpenoids 11

2.7 Biology and Pathogenecity of Test Organisms 11

2.7.1 Salmonella 11

2.7.2 Staphylococcus aureus 12

2.7.2.1 Source and Transmission of Staphylococcus aureus 12

2.7.2.2 Diseases Caused by Staphylococcus aureus 13

2.7.3 Escherichia coli 13

2.7.3.1 Diseases Caused by Escherichia coli O157: H7 14

2.7.4 Streptococcus spp 14

2.7.4.1 Streptococcus pneumonia 15

CHAPTER THREE

3.0 Materials and Methods 17

3.1 Sources of Materials 17

3.2 Sterilization of Materials 17

3.3 Media Used 17

3.4 Preparation of Garlic Extracts 17

3.4.1 Preparation of Different Concentration of Extract 18

3.4.1.1 Cold Water Extract 18

3.4.1.2 Hot Water Extract 18

3.4.1.3 Methanol Extract 18

3.4.3 Media Preparation 18

3.4.4 Agar Well Diffusion Method 18

3.5 Determination of Antibacterial Activity 19

3.6 Determination of Minimum Inhibitory Concentration (MIC) 19

3.6.1 Agar Well Diffusion Method 19

3.6.2 Disc Diffusion Method 20

3.7 Determination of Minimum Bactericidal Concentration (MBC) 21

CHAPTER FOUR

4.0 Results 21

CHAPTER FIVE

5.0 Discussion, Conclusion and Recommendation 27

5.1 Discussion 27

5.2 Conclusion 29

5.3 Recommendations 30

References