PUBLIC HEALTH HAZARDS OF SOME BACTERIAL PATHOGENS ASSOCIATED WITH CONSUMPTION OF EGGS AND STUDYING THE BEST COOKING METHODS FOR THEIR DESTRUCTION

Abstract

A total of 450 commercial eggs (Balady of farm hens and ducks), representing 150 eggs each, were randomly collected from markets, groceries, supermarkets and farmer's houses in Assiut City, Egypt [date not given]. Five eggs represent one sample. Shell surfaces, shell surfaces mixed with shell membranes and egg contents were examined for Staphylococcus aureus, Escherichia coli, Salmonella spp., Listeria spp., Aeromonas spp., Yersinia enterocolitica and Erysipelothrix spp. The best method for cooking eggs at different temperatures was also determined. Staph. aureus was the only microorganism isolated in Balady hen egg samples. It was recovered from 23.3, 13.3 and 10{%} of the shell surfaces, shell mixed with shell membranes and egg contents, respectively. In commercial farm hen eggs, Staph. aureus was isolated from both shell surface (23.3{%}) and egg contents (13.3{%}). S. enteritidis showed high rate of isolation from egg parts at 16.7, 10 and 10{%}, respectively. E. coli, Aeromonas spp. and Y. enterocolitica were also isolated. The highest rate of microbial contamination was observed in commercial duck eggs. Staph. aureus was recovered from shell surfaces (36.7{%}), shell mixed with shell membranes (30{%}) and egg contents (33.3{%}). E. coli was isolated in the shell (13.3{%}) and shell mixed with shell membranes (10{%}). Moreover, varying percentages of contamination by Salmonella, Listeria and Aeromonas spp. were recorded in different parts of duck egg. In addition, Y. enterocolitica was isolated from the shell (10{%}), shell mixed with shell membranes (3.3{%}) and egg contents (6.7{%}). The best method for cooking eggs was by Omelet method at 163°C for 25 min, which killed all the organisms tested. This was followed by open frying method where S. enteritidis was destroyed after 1 min. Staph. aureus and E. coli were completely destroyed after 12 min. Boiling for 7 and 12 minutes were adequate to destroy Staph. aureus and S. enteritidis, respectively, while, E. coli was able to survive. The economic and public health importance of some pathogens that affect human health through consumption of eggs are discussed. Measures to improve the quality of produced eggs and cook eggs to destroy microbial contaminants are also presented.