ABSTRACT

This study was carried to determine the occurrence of Staphylococcus aureus and Escherichia coli in yoghurt and ice cream and also to determine their susceptibility to antibiotics and the total viable count of the bacteria. Fifty (50) samples of yoghurt and fifty (50) samples of ice cream was analyzed for total viable counts which ranged from 1.4 x10⁶ CFU/ml - 2.0 x 10⁷ CFU/ml for Staphylococcus aureus  and the viable count of Escherichia coli  was ranged from 1.4 x10² CFU/ml - 2.0 x 10² CFU/ml. Staphylococcus aureus and Escherichia coli was isolated in a good number of the samples. Other organisms isolated are; Streptococcus spp, Staphylococcus epidermidis and Lactobacillus species. Their susceptibility of antimicrobials was carried out  to test for the sensitive and resistance drugs of the isolates. Some were resistance while some were sensitive to the antibiotics used. Escherichia coli isolates were resistant to Streptomycin, Tetracyclin and Sulfomethaxade and were sensitive to Ampicillin, Chlorophenicol, Gentamycin, Kanamycin and Amoxicillin. While Staphylococcus aureus isolates were resistant to Cloxacillin, Tetracyclin and Chloramphenicol and sensitive to other antibiotics. These isolates of pathogens from yoghurts and ice cream samples analyzed, poses a health risk to the consumers and these results indicates unhygienic conditions of food handlers and inadequate control during processing. Personal hygiene and processing industries should be adhered in order to avoid outbreak of yoghurt or ice cream drinks that have been contaminated.

TABLE OF CONTENTS

Title  page                                                                                                                  

Certification                                                                                                                i

Dedication                                                                                                                  ii

Acknowledgements                                                                                                    iii

Table of contents                                                                                                        iv

List of tables                                                                                                               vii

Abstract                                                                                                                       viiii

CHAPTER ONE

INTRODUCTION                                                                                                     1

1.1 Background of the Study                                                                                      1

1.2       Yoghurt and Ice cream                                                                                   3

1.2.1    Yoghurt                                                                                                           3

1.2.2    Ice Cream                                                                                                        4

1.3       Nutritional Value of Yoghurt                                                                         5

1.4       Essential Nutrients of yoghurts and ice cream                                               6

1.5       Yoghurt and Health                                                                                        8

1.6       Milk                                                                                                                 9

1.7       Fermentation                                                                                                   11

1.8      Drug Resistance                                                                                               12

CHAPTER TWO

LITERATURE REVIEW                                                                                          15

2.1       Qualities of milk used in yoghurt and ice cream preparation                         15

2.2       Pathogenic of Microorganisms in the Milk                                                    15

2.3       Significance of microorganisms in milk                                                         17

2.4       Spoilage of microorganisms in the milk                                                         17

2.5       Characteristics of Staphylococcus aureus and E.coli                                     18

2.6       Microorganisms in Milk                                                                                 20

CHAPTER THREE

METHODOLOGY                                                                                                    24

3.1    Materials and methods                                                                                      24

3.2    Preparation of the media                                                                                    24

3.2.1 Preparation of the Samples                                                                                24

3.2.2  Isolation and Enumeration of S.aureus and E.coli and Total Viable Counts   25

3.2.3  Characteristics and Morphological Identification                                            25

3.2.4   Gram Stain Test                                                                                               25

3.3      Coagulase Test                                                                                                 26

3.3.1   Catalase Test                                                                                                    26

3.3.2   Oxidase Test                                                                                                    27

3.3.3  Antimicrobial Susceptibility Test                                                                     27

CHAPTER FOUR

Result                                                                                                                          28

CHAPTER  FIVE

5.1   Discussion                                                                                                           34

5.2   Recommendation                                                                                                36

5.4   Conclusion                                                                                                          37

References