BACTERIOLOGICAL QUALITY AND ANTIBIOGRAM OF ISOLATES FROM HAMBURGER

ABSTRACT

The bacteriological quality and antibiogram of isolates of public health importance from twenty (20) samples of Hamburgers was investigated. The bacteriological quality of the burger samples were performed using standard microbiological method. The mean bacterial load of the samples from the different locations revealed that the counts were within the range of 4.1x105cfu/g to 6.4x105cfu/g. It was observed that the hamburger samples had the following prevalence; Escherichia coli (35%), Salmonella (13%) and Staphylococcus aureus (65%). For the E. coli isolates, 100% were resistant to ceftazidime, 100% to Augmentin and 71.4% to ceftriaxone. All the E. coli isolates were sensitive to Ciprofloxacin and Gentamicin. The results showed that the resistance of S. aureus isolates to Gentamicin, Augmentin, Ceftriaxone and Nitrofurantoin were 23.1%, 84.6%, 46.1% and 38.5% respectively. Percentage susceptibility levels of the S. aureus isolates to ofloxacin and nitrofurantoin were 76.9% and 61.5%, respectively. Multidrug resistant strains of S. aureus as well as the other isolates obtained in this study poses a risk factor for the public health. The results indicate that hamburgers could be a reservoir of E. coli. Since this strain is a food-borne pathogen, inspection of meat products for this bacterium is recommended.

TABLE OF CONTENTS

Title Page

Certification

Dedication

Acknowledgements

Table of Contents

List of Tables

List of Figures

Abstract

Chapter One: Introduction

1.0           Introduction                                                                                                               1

1.1       Aim and Objectives                                                                                                   4

Chapter Two                                                 

2.0       Literature Review                                                                                                      5      

2.1       Overview of Hamburgers                                                                                          5

2.2       History of Hamburger                                                                                               5

2.3       Nutritional Attributes of Hamburgers                                                                              7

2.3.1    Preparation and Storage of Burger                                                                                     7

2.4       Microorganisms found in Meat                                                                                          8

2.4.1    Listeria monocytogenes                                                                                             8

2.4.2    Salmonella                                                                                                                        10

2.4.3    Escherichia coli                                                                                                       11

2.4.4    Staphylococcus aureus                                                                                            12

2.5       Contamination during Handling and Processing                                                          13

2.5.1    Meat as Source of Contamination of Burgers                                                        15

2.6       Consequences of Food-Borne Diseases from Microorganisms                               19

2.7    Studies on Isolation of Microorganisms from Burgers                          21

2.8       Antimicrobial Resistance                                                                                      23

2.8.1     Transmission between Human and Animal due to Indirect Pathways                24

2.8.2     Direct Pathways                                                                                                                 24

2.8.3    Food-borne Transmission                                                                                        25

2.9       Ensuring Food Safety of a Hamburger                                                                    26

Chapter Three

3.0       Materials and Methods                                                                                            27

3.1       Sample Collection                                                                                                   27

3.2       Sterilization of Equipments                                                                                     27

3.2.1    Culture Media Preparation                                                                                      27

3.3       Isolation, Enumeration and Identification                                                               27

3.4       Gram staining                                                                                                          28

3.5       Biochemical Tests                                                                                                  29

3.5.1    Catalase Test                                                                                                            29

3.5.2    Indole Production Test                                                                                            29

3.5.3    Citrate Utilization Test                                                                                            29

3.5.4    Hydrogen Sulfide Production Test                                                                          30

3.5.5    Methyl Red Test                                                                                                      30

3.5.6    Voges-Proskauer test                                                                                               30

3.5.7    Urease Test                                                                                                              30

3.6       Antibiotics Susceptibility testing                                                                            30

Chapter Four

4.0       Results                                                                                                                     32

Chapter Five

5.0       Discussion and Conclusion                                                                                     41

5.1       Discussion                                                                                                                41

5.2       Conclusion                                                                                                               44

References                                                                                                              45

LIST OF TABLES

LIST OF FIGURES

CHAPTER ONE

1.0     INTRODUCTION

Food poisoning and food safety have become very topical subjects, eliciting a great deal of public concern to many people all over the world. This is a result of emerging foodborne pathogens that continue to cause outbreaks of food borne diseases in different countries (WHO, 2013). A wide variety of diseases are caused by eating food contaminated with pathogenic microorganisms or their products; by no means all these diseases can be classed as food poisoning. Foodborne disease outbreaks have heightened the awareness of foodborne pathogens as a public health problem around the world (Koutsoumanis et al., 2008).

Food security is a complex issue, where animal proteins such as meats, meat products, fish and fishery products are generally regarded as a high risk commodity to infection and toxication (Yousef et al., 2008). These food borne infections and the consequent illnesses are some of the major international challenges that lead to high mortality and economic loss (Adak et al., 2005). In the industrialized world, food borne infection cause considerable illnesses that heavily affect healthcare systems (Adak et al., 2005; Clarence et al., 2009). Safe food is a major global public health concern and is a basic human right (Ercolini et al., 2006). Foodborne illnesses (with symptoms of diarrhea and vomiting) are often not considered serious health threats in most developing nations and typically go unreported (Olesen and Jespersen, 2010). The lack of effective surveillance systems is the main reason for underreporting and the consequent inaccurate estimation of the burden associated with foodborne diseases.

Fecal contamination of raw and cooked meats, sandwiches and other foods has been identified as the cause of foodborne illness in many parts of the world (Koutsoumanis et al., 2008). A wide spectrum of pathogenic microorganisms (Salmonella, Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Shigella) has been identified in contaminated food products (mostly meat, dairy products, fish, and rice).

Beef burgers are important and popular food items of highly nutritious and highly desirable foods for human being, on the other hand, they are considered as an ideal culture medium for growth of many organisms because of the high moisture, the high percentage of nitrogenous compounds, plentiful supply of minerals, some fermentable carbohydrates (glycogen) and of a favorable pH for most microorganisms resulting in their spoilage, economic losses, foodborne infections in human and health risk (Pennacchia et al., 2011).

The quality of meat product used in making the hamburgers may be compromised as they may be contaminated during processing from the hands of workers, workers clothes, knives, the hide, the gut or from the environment and transportation resulting in an inferior or even unfit quality for human consumption. The most important bacterial pathogens in beef meat and meat products that are responsible for food-borne infections include E. coli, Salmonellae, coagulase positive S. aureus and Pseudomonas.

Pelczar et al. (2006) reported the prevalence of Campylobacter spp., Staphylococcus spp., Escherichia coli, Salmonella spp., Yersinia spp. and Listeria on meat, sea foods, beef burger sandwiches, poultry products and on the hands of food workers (Pelczar et al., 2006).

Food spoilage is defined as any change that makes a product unacceptable for human consumption. It can result from different causes involving physical-chemical and biochemical changes and also microbial growth and activity. In particular, microbial growth and activity are the most important causes of reduction of quality and shelf life of foods. Food borne diseases are diseases resulting from ingestion of bacteria, toxins and also cells produced by microorganisms present in food (Clarence et al., 2009). The intensity of the signs and symptoms may vary with the amount of contaminated food ingested and susceptibility of the individuals to the toxin.

Meat and meat products are sometimes contaminated with germs after leaving the manufacture plant and during handling (Stagniitta et al., 2006). Hygiene conditions are poor when foods are produced in non-industrial establishments, mainly due to insufficient monitoring during processing. These contaminated food ends up infecting or intoxicating children, elderly and immunosupressed individuals who are highly susceptible (Stagnitta et al., 2006). Meat is an important source of protein and a valuable commodity in resource-poor communities (Datt et al., 2003; Garcia, 2007). However, while meat is a rich nutrient source, it can also be a potential vehicle of human foodborne illnesses (FAO/WHO, 2013). Inappropriate slaughtering and retail operation can compromise food safety and more so, in densely populated areas like informal settlements (Garcia, 2007). Slaughtering process is frequently unhygienic and this makes meat to be easily contaminated. Meat products from such condition often deteriorate rapidly and pose a health hazard (Datt et al., 2003; FAO/WHO, 2013).

The spoilage of meat can occur as strong off-odours and off-flavours, discoloration, superficial slime, uncontrolled acidification, putrefaction and presence of fluorescence (Nychas et al., 2008).  Wide ranges of microorganisms from different sources can be transferred onto meat at different moments of the production: before the slaughter, during slaughter and post mortem. Before the slaughter, the contamination is usually due to intestinal microorganisms and it happens if the animal is much stressed or under ill health. During the slaughter it is caused by environmental and intestinal bacteria, conveyed by contaminated tools, operators and delayed evisceration. The post mortem contamination is due to environmental microorganisms and usually affects the surface of meat (Volonterio, 2005).

Since the first use of antimicrobial agents for the treatment of bacterial infections, the problem of acquired resistance has been notified. In both veterinary and human medicine, the prevalence of resistant strains rises year after year. This could be a public health risk, especially when there is transmission of antimicrobial resistance from one species to another and in particular to human.

1.1       Aims and Objectives

i.               To isolate and identify bacteria of public health importance on the hamburgers.

ii.              To determine the bacteriological load on hamburgers from different fast foods and supermarkets

iii.            To ascertain the antibiotic susceptibility profile of the organisms isolated from hamburgers.

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