PREVALENCE AND ANTIBIOTIC SUSCEPTIBILITY PROFILE OF Bacillus cereus ISOLATED FROM MILK CURD SOLD IN SOME SELECTED AREAS IN OGUN STATE, NIGERIA.

The antibiotic susceptibility of Bacillus cereus isolated from ten (10) wara samples collected from Ago-Iwoye Market, Ijebu-ode Market and Paapa Sango Market was investigated using standard microbiological methods. Isolation of Bacillus cereus was done by the spread plate method using selective agar Polymyxin B and Nutrient agar. The total aerobic plate counts and total coliform counts were determined by the spread plate method on Nutrient Agar and MacConkey Agar respectively. The antimicrobial susceptibility of the isolated Bacillus cereus to antibiotics was determined by the disk diffusion method.All the ten (10) wara samples were positive for Bacillus cereus and a total of 14 Bacilluscereus were isolated. The total aerobic plate count had a mean of 5.67 x 10⁶ which ranged from 2.01 x 10⁷ to 8.8 x 10⁶cfu/g. Total coliform counts had a mean of 3.1 x 10⁶ and ranged from 1.0 x 10⁷ to 8.4 x 10⁷ cfu/g.All Bacillus cereus were found to be resistant to three (3) or more of the eight antibiotics used. The antibiotics that shows the highest resistance in percentage was Augmentin (100%), Tetracycline (100%), Amoxicillin (100%), Cotrimycin (100%). Bacillus cereus were susceptible to Ofloxacin (70%), Nitrofurantoin (40%), Nalidixic acid (20%) and Gentamycin (32%).The study therefore recommended that handler and consumers of soft cheese should maintain proper hygiene in order to avoid high numbers of Bacillus cereus at the stage of consumption. Soft cheese should be eaten soon after production, or kept hot (above 63°C) or cooled rapidly and kept below 7-8°C (ideally below 4°C), preferably for a short time.

TABLE OF CONTENTS

CHAPTER ONE: INTRODUCTION

1.1       Introduction

1.2       Background to the study

1.3       Objective of the study

1.4       Significance of the study

CHAPTER TWO: LITERATURE REVIEW

2.1       Soft cheese “wara”

2.2       Bacillus cereus

2.2.1    Taxonomy of the Bacillus cereus group

2.2.2    Occurrence

2.2.3    Morphological and biochemical characteristics

2.3       Foodborne poisoning caused by Bacillus cereus                                           

2.3.1    Virulence factors of Bacillus cereus linked to foodborne poisoning

2.3.1.1 Emetic foodborne intoxication

2.3.1.2 Diarrhoeal foodborne infection

2.4       Specific control measures

2.4.1    Effect of temperature on growth

2.4.2    Effect of pH on growth

2.4.3    Effect of water activity on growth

2.4.4    Effect of sodium chlorine

2.4.5    Effect of modified atmosphere packaging

2.4.6    Effect of heating

2.4.7    Effect of other processes

2.5       Bacillus cereus sensitivity to antibiotics

CHAPTER THREE: MATERIALS AND METHODS

3.1       Sample collection

3.2       Sterilization and aseptic techniques

3.3       Instrument and glassware

3.4       Media used

3.5       Isolation of Bacillus Cereus

3.5.1    Sample preparation

3.5.2    Total aerobic plate Count

2.5.3    Total Coliform Count

3.5.4    Selective Isolation of Bacillus cereus                                                            

3.5.5    Purification of Isolates

3.6       Identification of Bacillus cereus isolates

3.6.1    Morphological characteristics

3.6.2    Microscopic examination

3.6.3    Biochemical tests

3.7       Antibiotic susceptibility

CHAPTER FOUR: RESULTS

4.1       Total aerobic plate count

4.2       Total coliform count

4.3       Identification of isolates

4.4       Antibiotics sensitivity test

CHAPTER FIVE:      DISCUSSION, CONCLUSIONAND RECOMMENDATIONS

5.1       Discussion

5.2       Conclusion

5.3       Recommendations

REFERENCES

Appendix I

Appendix II

Appendix III