ABSTRACT 

The upsurge in the prevalence of side effects of many synthetic antimicrobial agents and incidence of multidrug resistant bacteria has spurred scientists on the research for plant based antimicrobial of therapeutic potentials. Azadirachta indica and Psidium guajava present such potential of high medicinal value. These plants are used in Nigeria traditionally as condiments and for treatment of various ailments such dental plague . The phytochemical composition of Azadirachta indica and Psidium guajava showed the presence of Tannin, Alkaloid, Saponin and Flavonoid. Aqueous and ethanol extracts of Azadirachta indica and Psidium guajava leaves were screened for antibacterial activity against Candida albican and Streptococcus mutans. Both extracts were found to exhibit selective inhibition against the isolates. The diameter zones of inhibition exhibited by the extracts were between 2 ± 0.01 – 10 ± 0.10 mm. The Minimum Inhibitory Concentration (MIC) determined by the agar diffusion method was between 10.00 and 2.50 mg/ml-1. Ethanol extracts showed more `inhibitory effect compared to the aqueous extracts. Results obtained show that the extracts of Azadirachta indica and Psidium guajava possess some level of antibacterial activities against Steptococcus mutans and Candida albicans.

TABLE OF CONTENTS

Title Page i

Certification ii

Dedication iii

Acknowledgements iv

Table of Contents v

Lists of Tables vii

Abstract viii

CHAPTER ONE

1.0 Introduction  1

1.1  Aims and Objectives 4

1.2  Objectives 4

CHAPTER TWO

2.0 Literature Review 5

2.1 Dogoyaro/Neem (Azadirachta indica) 5

2.2 Phytochemicals of Azadirachta indica 8

2.3 Antimicrobial Activity 9

2.4 Antibacterial and Anti-Fungal Activities 10

2.5 Guava (Psidium guajavaLinn.) 10

2.6 Streptococcus mutans 14

2.7 Candida albicans 15

CHAPTER THREE

3.0      Materials and Methods 17

3.1 Collection of Samples 17

3.2  Media Used 17

3.3 Sterilization 17

3.4 Collection of Test Organisms 17

3.5 Isolation and Identification of Bacteria and Fungi 17

3.6 Preparations of Plant Extracts 18

3.7 Phytochemical Analysis 18

3.7.1 Test for alkaloid 18

3.7.2 Test for flavonoid 19

3.7.3 Determination of saponins 19

3.7.4 Test for tannin 20

3.8 Antibiotic Sensitivity Testing 20

3.8.1 Agar diffusion method 20

3.9 Determination of Minimum Inhibitory Concentration (MIC) 20

CHAPTER FOUR

4.0  Results 22

CHAPTER FIVE 

5.0       Discussion Conclusion Recommendation 27

5.1 Discussion 27

5.2 Conclusion 28

5.3 Recommendation 28

References 29