ABSTRACT

The present study aimed at comparing the microbiota of stool of healthy persons and the microbiota of the diarrhoeic stool of patients with gastrointestinal tract infection. A total of 50 stool samples were used for the study, of which 30 were diarrhoeic stool samples of patients being diagnosed of gastroenteritis in Abia State University Teaching Hospital (ABSUTH), Aba while the remaining were 20 formed stool samples collected from healthy individuals in Michael Okpara University of Agriculture Umudike, (MOUAU). All the stool samples were cultured on Salmonella-Shigella agar and the growths were identified using biochemical tests and by Gram staining. The biochemical results and Gram staining results showed that all the isolates from the stool samples were Salmonella and Shigella spp. Out of the 50 stool samples collected 14(28%) were positive for bacteria growth, 13(26%) of the growth were observed in the diarrhoeic stool samples of the patients, of which 9(18%) were Salmonella spp and 4(8%) were Shigella spp while the remaining 1(2%) growth was observed in the formed stool samples and the growth were only Salmonella species. The antimicrobial testing showed that the Salmonella and Shigella isolates were very sensitive to Ciprofloxacin and Ofloxacin with 70% and 100% sensitivity for Ciprofloxacin, and 60% and 75% for Ofloxacin but showed high resistances to Ceftriaxone, Augmentin and Ampicillin wit . The present study indicates that Salmonella spp and Shigella spp are more prevalent in the diarrhoeic stool of patients than in the microbiota of stool of healthy individuals which shows that they are responsible for gastrointestinal tract infection. The study also indicates that Ciprofloxacin and Ofloxacin can be used as first line therapies for Salmonella and Shigella gastroenteritis.

TABLE OF CONTENTS

Title Page i

Certification ii

Dedication iii

Acknowledgements iv

List of Tables viii

List of Figures ix

Abstract              x

CHAPTER ONE: INTRODUCTION

1.1 Background to the study    1

1.2 Significance of the study    3

1.3 Limitations of the study    3

1.4 Justification of the study    4

1.5 General aim of the study    4

1.5.1 Specific aim of the study                4

CHAPTER TWO: LITERATURE REVIEW

2.1 General overview of Gastrointestinal tract infections    5

2.1.1 Pathogens associated with Gastrointestinal tract infections    6

2.2 Salmonella as a Gastro enteric pathogen    6

2.2.1 History of Salmonella    6

2.2.2 Taxonomy and Nomenclature of Salmonella    7

2.2.3 Epidemiology of Salmonella    8

2.2.4 Pathogenesis of Salmonella    8

2.2.5 Isolation of Salmonella from stool samples   11

2.2.6 Sources of Salmonella   12

2.3 Shigella as a Gastro enteric pathogen   13

2.3.1 History of Shigella                             13

2.3.2 Epidemiology of Shigella                                       13

2.3.3 Pathogenesis of Shigella                                       15

2.3.4 Isolation of Shigella from stool samples               17

2.4 Characterization of Salmonella and Shigella spp   17

2.4.1 Cultural characteristics of Salmonella spp                             17

2.4.2 Biochemical characteristics of Salmonella                           17

2.4.3 Cultural characteristics of Shigella spp               18

2.4.4 Biochemical characteristics of Shigella spp    18

2.5 Antibiogram study of Salmonella and Shigella spp                19

2.5.1 Antibiogram study of Salmonella                  19

2.5.2 Antibiogram study of Shigella    19

CHAPTER THREE: MATERIALS AND METHODS

3.1 Description of study area    20

3.2 Sample collection and study design                20

3.2.1 Study design    20

3.3 Media and Media preparation    21

3.4 Isolation and Identification of bacteria from the stool of healthy individuals             22

3.4.1 Inoculation and Incubation of stool samples    22

3.5 Isolation and Identification of Bacteria from diarrheic stool samples of patients        22

3.5.1 Inoculation and incubation of the stool samples                 22

3.6 Characterization of Bacteria isolates from the two groups                 23

3.6.1 Gram staining     23

3.6.2 Triple sugar iron test     23

3.6.3 Citrate test                 24

3.6.4 Urea test     24

3.6.5 Motility-Indole-Ornithine test     24

3.6.6 Lysine Iron agar test     25

3.6.7 Methyl Red test     25

3.6.8 Voges Proskeaur test     25

3.7 Antimicrobial Susceptibility test     26

CHAPTER FOUR: RESULT 

4.1 Result                         27-36

CHAPTER FIVE: DISCUSSION, CONCLUSION AND RECOMMENDATION

5.1 Discussion                 37

5.2 Conclusion                                                                                                                     41

5.3 Recommendation                                                                                                           41

 References

Appendixes