ISOLATION AND IDENTIFICATION OF BACTERIA FROM FOOD VENDORS

ISOLATION AND IDENTIFICATION OF BACTERIA FROM FOOD VENDORS

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ABSTRACT

Hawked foods are cheap and easily accessible and have met the food needs of people in many cities and towns of developing countries. This study was aimed at ascertaining the diversity of microbial contaminants in foods hawked in Nsukka town. Seven different food samples of cooked foods hawked in Nsukka were examined for the presence of bacterial and fungal contaminants using streak plate method on sterile nutrient agar plates and SDA plates respectively. The foods included; pigeon pea with yam (ayarayaji), pigeon pea with maize (ayaraya oka), pigeon pea with cocoyam (achicha), bambara nut (okpa), rice and stew, maize meal (igbangwu) and maize meal (agidi jellof). Eighteen species of bacteria were isolated and identified using microbiological and biochemical methods. These were Staphylococcusaureus (n=1), Enterobacter aerogenes (n=1), Shigella dysenteriae (n=1), Bacillus spp. (n=12) and Bacillus megaterium (n=3). Ten species of fungi were also isolated and identified. They include Candida spp. (n=7) and Aspergillus spp. (3). The most predominant isolates were Bacillus spp. and Candida spp. All the bacterial isolates were sensitive to levofloxacin, gentamicin, erythromycin, amoxicillin, streptomycin and chloramphenicol. Six isolates were resistant to ampiclox, followed by rifampicin (5), ciprofloxacin (4), and norfloxacin (1). Staphylococcus auerus., Enterobacter aerogenes and Shigella dysenteriae were sensitive to levofloxacin, ciprofloxacin, norfloxacin, gentamicin, amoxicillin, streptomycin, rifampicin, erythromycin, and chloramphenicol. The fungal isolates were all sensitive to itraconazole. One of the fungal isolates was resistant to ketoconazole, four were resistant to fluconazole and five to griseofulvin. Eighty percent of the isolates were resistant to nystatin. The multiple antibiotic resistance indices were low for all the antimicrobial agents used (antibacterial and antifungal). MAR indices of six of the fungal contaminants were high, indicating that the organisms have originated from environment where antibiotics were often used. The Aspergillus species were examined using Polymerase Chain Reaction (PCR) for resistant gene MDR3 and CYP51. Result showed that the Aspergillus species had the resistant gene MDR3 in them. The result of this study revealed that cooked foods hawked in Nsukka town are contaminated with both bacteria and fungi. These organisms showed sensitivity and resistance activities to the antimicrobial agent used. Ready to eat foods hawked in Nsukka also harbor multidrug resistance food borne bacteria and fungi which might cause public health hazards if these antibiotics resistance organisms are transferred to human.

CHAPTER ONE

INTRODUCTION

1.1     Background of Study

Bacterial are group of microorganism all of which lack a distinct nuclear membrane (and hence are considered more primitive than animal and plant cells) and most of which have a cell wall of unique composition. Most bacterial are unicellular; the cells may be spherical (coccu) rod – shaped (bacillus), spiral (spirillum), comma – shaped (vibrio) or corkscrew-shaped (spierocheate). Generally, they range in size between 0.5 and 5um. (Elizabeth and Martin, 2003).

Food is any substance that people or animal eat or drink or that plants absorb to maintain life and growth. Food is any substance consumed for nutritional support for the body; it is usually of plant or animal origin (Ezeronye, 2007). Food consists of chemical compounds which heterophilic living thing consumes in order to carry out metabolic processed. They are also substances which when introduced to the digestive system under normal circumstances contribute to growth, repair and production of energy (Ezeronye, 2007). Foods are classified into six essential nutrients known as protein, carbohydrate, vitamin mineral, fat and oil, water.

PROTEIN: One of a group of organic compounds of carbon, hydrogen, oxygen and nitrogen (sulphur and phosphorus may also be present). The protein molecule is a complex structure made up of one or more chains of amino acid, which are linked by peptide bonds. Proteins are essential constituents of the body; they form the structural material of muscles, tissues, organs, etc. and are equally important as regulators of function, as enzymes and hormones, proteins are synthesized in the body from their constituent amino acids, which are obtained from the digestion of protein in the diet (Elizabeth and Martin, 2003).

CARBOHYDRATE: One of a large group of compounds, including the sugar and starch, that contain carbon, hydrogen and oxygen and have the general formula CX (H20) Y- Carbohydrates are important as a source of energy: they are manufactured by plants and obtained by animals from the diet, being one of the three main constituent of food. All carbohydrates are eventually broken down in the body to the simple sugar glucose which can then take part in energy producing metabolic processes. Excess carbohydrate, not immediately required by the body is stored in the liver and muscles in the form of glycogen. In plants carbohydrate are important structural materials (e.g. cellulose and storage products (commonly in the form of starch) (Elizabeth and Martin, 2003).

VITAMIN: Any of a group of substances that are required in very small amounts, for healthy growth and development: they cannot be synthesized by the body and are therefore essential constituents of the diet. Vitamins are divided into two groups, according to whether they are soluble in water or fat. The water soluble groups include the vitamin C; the fat soluble vitamins are vitamins A, D, E and K. Lack of sufficient quantities of any of the vitamins in the diet results in specific vitamin deficiency diseased (Elizabeth and Martin, 2003).

FAT: A substance that contains one or more fatty acids (in the form of triglyceride) and is the principal form in which energy is stored by the body (in adipose tissue). It also serves as an insulating material beneath the skin (in the subcutaneous tissue) and around certain organs (including the kidney). Fat is one of the three main constituents of food; it is necessary in the diet to provide an adequate supply of essential fatty acid and from the efficient absorption of fat –soluble vitamins from the intestine. Excessive deposition of fat in the body leads to obesity (Elizabeth and Martin, 2003).

1.2     Statement of Problem

A vendor is a person selling something (en.Wikipedia org/Wiki/vendor). The world Health Organization (WHO) Indicated that food-borne diseases most of which are of microbial origin are perhaps the most widespread problems in the contemporary world and this is responsible for about one third of death worldwide, through infectious conditions with adverse effects can reduce economic productivity. Poor sanitary condition in most of the local markets and the environment being highly polluted and charged with spoilage and pathogenic flora is likely the source of contamination of food items sold by such vendors (Oweghe et al., 2001). It is known that poor hygienic conditions in a food environment may encourage the multiplication of pathogenic organisms in food (Egeonu, 2002). It has been observed that Bacillus cereus and Staphylococcus aureus grow to oxygenic levels in food at 300c (Egeonu, 2003). Therefore microbiological examination of foods and food contact surfaces may provide information concerning the quality of the raw food, and the sanitary conditions under which the food is processed (Michael et al; 2004). Microorganisms live throughout the kitchen and can easily move around by attaching themselves to people easily move around by attaching themselves to people, food and equipment. Bacteria may pass from equipment to food which has not been properly cleaned and sanitized before being used to prepare another food. This implies that the food to be consumed by humans should be pure and free from contamination especially by pathogenic and spoilage microorganisms. Failure to ensure the safety and wholesomeness of the food consumed by the public might lead to some illness. To reduce contamination by microorganisms to a minimum level, and obtain good keeping quality of the products, the raw materials should regularly be monitored and examined.

Food contacts surfaces are a major concern for food service facilities in controlling the spread of food-borne pathogens, surfaces such as bench tops, table, etc. may have bacterial on them from contact with people, raw foods, dirty equipment or other things such as cartons that have been stored on the floor. If the bench tops are not properly cleaned, any food on them will be contaminated by the bacterial (Kamil, 2005).

1.3     Research Objectives

The overall objective of this work is to access selected foods sold by vendors in Nsukka town, Enugu for bacterial contamination. The specific objectives are however given as;

1. To isolate and identify bacterial species associated with food contamination.

2. To determine the microbial load of isolated bacteria.

3. To establish the public health implication of consumption of such foods.

1.4     Research Questions

1. What are the bacterial species associated with food contamination?

2. What is the microbial load of isolated bacteria?

3. What is the public health implication of consumption of such foods?

1.5     Significance of Study

Food is very important for the sustenance of the human health. However, the preparation of foods is often associated with inadvertent contamination by microorganisms. Food contamination by antimicrobial resistant organisms has become a serious problem in public health. The emergence of resistant organisms has been observed to be as a result of inappropriate use of antibiotics. Evidence has shown that the use of antibiotics in animal has resulted to resistance food borne pathogens that may be transmitted to humans as food contaminants. This study was designed with a view to ascertain the diversity of bacterial and fungal contaminants in foods hawked. The microbial contaminants are to be isolated, identified, and their susceptibilities to commonly available antibiotics determined. For resistant isolates, the possible resistance gene(s) involved will be identified. The findings will be discussed in relation to the potential public health implications of eating microbial contaminated foods and will be of immense benefit to the public as well as food related organisations.


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