ISOLATION AND IDENTIFICATION OF BACTERIA FROM FOOD VENDORS

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 contaminantswere 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 generalformula 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 canthen 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 smallamounts, 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 thekidney). 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 provideinformation concerning the quality of the raw food, and the sanitary conditions under which the food is processed (Michael et al; 2004).

ISOLATION AND IDENTIFICATION OF BACTERIA FROM FOOD VENDORS