Bacteriological Quality and Occurrence of Escherichia Coli and Staphylococcus Aureus in Ice Cream Sold in Zaria Metropolis, Nigeria.
ABSTRACT
A cross-sectional study was conducted to determine the bacteriological quality and occurrence of Escherichia coli and Staphylococcus aureus in ice cream sold to consumers by supermarkets and street vendors in Zaria metropolis.
240 samples of industrially and locally produced ice creams were examined for the total aerobic and coliform counts as well as contamination with Staphylococcus aureus and Escherichia coli species using standard methods.
The isolated S. aureus and E. coli were further subjected to antimicrobial susceptibility testing by the disk diffusion method. Overall, the mean total counts (TAPC) per ml of industrial and locally produced ice cream were 1.14 x 107
and 2.015 x107 respectively which were statistically significantly different (P<0.05) and the mean counts for coliforms (TCC) per ml for industrial ice cream and local ice cream were 5.69 x 103 and 4.73 x 103 respectively .
Of the total of 240 samples, comprising 111 industrially produced and 129 local ice cream samples, 19 (8.0%) were positive for Staphylococcus aureus and 5 (2.0%) were positive for Escherichia coli; 5(26.3%) of the Staphylococcus aureus isolates were from industrially produced ice cream while 14 (73.6%) were from locally made ice cream .
TABLE OF CONTENTS
Cover Page…………………………………………………………………………………………………………. i
Title Page…………………………………………………………………………………………………………….. ii
Declaration…………………………………………………………………………………………………………. iii
Certification………………………………………………………………………………………………………… iv
Acknowledgement………………………………………………………………………………………………… v
Abstract………………………………………………………………………………………………………………. vi
Table of Contents……………………………………………………………………………………………………. viii
List of Tables………………………………………………………………………………………………………….. xii
List of Appendices……………………………………………………………………………………………………. xiii
CHAPTER ONE: INTRODUCTION……………………………………………………………………………………….. xii
- The Genera Staphylococcus and Species Escherichia Coli……………………………….. 1
- Statement of Research Problem……………………………………………………………………… 2
- Justification………………………………………………………………………………………………….. 3
- Aim of the …………………………………………………………………………………………… 4
- Objectives of the Study………………………………………………………………………………….. 4
- Research Questions……………………………………………………………………………………….. 5
CHAPTER TWO: LITERATURE REVIEW……………………………………………………………………………… 6
- Definition of the Genus Staphylococcus…………………………………………………………… 6
- Genome …………………………………………………………………………………. 6
- Natural habitats of Staphylococcus species………………………………………………………. 6
- Reservoirs of ………………………………………………………………………….. 7
- Pathogenic members of the genus …………………………………………… 7
- aureus infection in Man……………………………………………………………………………… 7
- Isolation and identification of aureus……………………………………………………….. 10
- Epidemiology of aureus…………………………………………………………………………… 10
- Virulence factors of aureus……………………………………………………………………….. 13
- Toxins……………………………………………………………………………………………………… 12
2.1.8.2. Pyrogenic toxin superantigens (PTSAgs)……………………………………………………. 13
- Exfoliative toxins (EF toxins)…………………………………………………………………….. 13
- Other toxins…………………………………………………………………………………………….. 14
- Prevalence and occurrence of aureus in food……………………………………………… 14
- Treatment of aureus infection and antibiotics resistance…………………………… 15
- Phage therapy…………………………………………………………………………………………… 16
- Mechanisms of antibiotic resistance by aureus………………………………………….. 17
- Molecular Epidemiology of Staphylococcus aureus………………………………………… 19
- Typing Methods For MRSA…………………………………………………………………………. 18
- Diagnosis of MRSA………………………………………………………………………………………. 21
- Molecular typing methods for MRSA……………………………………………………………. 22
2.4.2. Treatment of S. aureus and MRSA……………………………………………………………… 22
- Prevention and control of MRSA infection…………………………………………………….. 24
- Control of MRSA infection in humans…………………………………………………………. 24
- Screening programs………………………………………………………………………………….. 25
- Surface sanitization…………………………………………………………………………………. 25
- Hand washing………………………………………………………………………………………….. 25
- Decolonization…………………………………………………………………………………………. 26
- Control and prevention of MRSA infection in animals…………………………………….. 26
2.4.4.5 The therapeautic animal handlers……………………………………………………………… 26
- Escherichia coli……………………………………………………………………………………………. 28
- Escherichia coli………………………………………………………………………………………….. 28
- Escherichia coli O157:H7…………………………………………………………………………… 30
- History of Escherichia coli O157:H7…………………………………………………………….. 31
- Geographic distribution and outbreak data of coli O157:H7…………………………. 33
- Reservoir and sources of coli O157:H7 infection………………………………………… 34
- Symptoms and effects of coli O157:H7 infection………………………………………… 36
- Treatment and cure of infection……………………………………………………………………. 37
- Prevention and Control of coli O157:H7 Infections……………………………………. 38
CHAPTER THREE: MATERIALS AND METHODS………………………………………………………. 40
- Materials……………………………………………………………………………………………………… 40
- Study Site…………………………………………………………………………………………………….. 40
- Study Design………………………………………………………………………………………………… 41
- Sample Size………………………………………………………………………………………………….. 41
- Isolation of Staphylococcus aureus and Escherichia Coli from Ice cream in Zaria 42
- Sample collection and handling…………………………………………………………………….. 42
- Sample preparation……………………………………………………………………………………… 42
- Determination of total aerobic plate …………………………………………………….. 42
- Total coliform …………………………………………………………………………………. 43
- Isolation procedure for Staphylococcus aureus……………………………………………….. 43
- Isolation procedure for Escherichia coli…………………………………………………………. 43
- Identification of Staphylococcus and coli species………………………………………… 43
- Conventional biochemical test for Staphylococcus and coli…………………………. 44
- Catalase ……………………………………………………………………………………………. 44
- Coagulase test………………………………………………………………………………………….. 44
- Sugar fermentation test……………………………………………………………………………… 45
- Pigmentation test on Mannitol Salt Agar (MSA)…………………………………………… 45
- Identification of aureus and E.coli isolates based on conventional biochemical tests.
………………………………………………………………………………………………………………………….45
- Micobact testing of Staphylococcus and coli species…………………………………… 46
- Determination of the Susceptibility of aureus and E.coli to Commonly Used Antimicrobial Agents……………………………………………………………………………………….. 47
- Statistical Analysis……………………………………………………………………………………….. 47
- RESULTS…………………………………………………………………………………………………… 49
- Results of Bacteriological Quality of Industrial and Locally Produced ice creams Sold in Zaria……….. 49
- Results of TAPC of industrial and local ice creams………………………………………….. 49
- Results of TCC of industrial and local ice creams……………………………………………. 51
- Frequency and Percentage Occurrence of aureus and E. coli in Ice cream Sold in Zaria…………….52
- Absence of coli O157:H7……………………………………………………………………………. 54
- Multiple Antibiotic Resistance Index of aureus Isolates from Ice creams Isolated in Zaria……….. 57
INTRODUCTION
1.1 Background of the Study
Ice cream is a frozen dairy food made by freezing a processed mix. The mix is composed of a combination of milk products (condensed milk, milk powder and cream), sugar, emulsifiers, stabilizers, flavouring and colouring agents ( Kocak et al.,1998).
Ice cream is a palatable, nutritive and healthy food. It is undoubtedly one of the most popular and favourite food products in Nigeria among children and adults especially during hot season. Several brands of ice cream with a variety of flavours are being marketed in Nigeria.
Carbohydrate solutions give the sensation of sweetness and control the frozen and melting characteristics of ice cream. Ice cream mix properties depend primarily on lipid and protein quantities. The small quantities of emulsifier and hydrocolloid act as stabilizers of oil-in- water emulsions.
For flavouring, natural flavours may be used such as real fruit, cocoa, coffee, ginger and vanilla. All these allow great variations in ice cream flavour, taste and way of structure formation (Vica et al., 2010).
As food, ice cream is a very nourishing product, with a great energy value due to its rich content in carbohydrates, lipids and proteins. It also contains vitamins (especially vitamin A and B) and mineral salts especially calcium and phosphorus salts.
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