BACTERIOLOGICAL EVALUATION OF UNCOOKED EGGS

ABSTRACT

This study was aimed at isolating and characterizing bacteria associated with uncooked eggs.

Eight egg samples were collected from four randomly selected vendors at different locations. Sterile swab moistened in sterile distilled water, was applied to the egg surface and the swabs were submerged in 5 ml sterile distilled water as shell wash. Also, a sterile scalpel blade was used to make a small hole on the shell through which the egg content was aseptically emptied into a sterile container, and mixed thoroughly. 1 ml of the shell wash and egg contents were inoculated into prepared Nutrient agar, MacConkey agar and Salmonella Shigella agar plates by pour plate method. Heterotrophic, coliform and Salmonella counts in an index of 10³cfu/ml obtained from both the shell wash and egg content samples indicate a heavy contamination of the egg samples. The result revealed that the egg samples harboured four bacterial species which includedStaphylococcus sp., Bacillus sp., Escherichia coli and Salmonella sp., indicating a diversity of bacterial species in uncooked eggs. Salmonella sp., which was isolated from seven of the eight shell samples and three of the egg content samples, is a highly reported pathogenic microorganism for humans. Escherichia coli which was isolated from majority of the samples, especially the shell samples, is considered as one of the most common bacteria causing diarrhoea especially in children and immunosuppressed persons. Staphylococcus sp., which was the most isolated bacteria in the shell samples, was reported as the most dominating microflora in the air of poultry houses. The isolation canalso be attributed to poor handling, as Staphylococcus is a notable human skin flora. Egg should be consumed when properly cooked or fried. If it must be consumed raw, it should be subjected to techniques proven to decontaminate the egg shell surface as well as destroy bacterial cells in the egg content. Egg safety therefore becomes everybody’s responsibility and not just the famers’ or vendors’.