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

representing A total of 450 commercial eggs (Balady of farm hens and ducks)
150 eggs for each were collected randomly from Assiut city markets, different
groceries, supermarkets and farmer's houses. Every 5 eggs represent one
sample. Shell surfaces, shell surfaces mixed with shell membranes and egg
contents were examined for the isolation of some pathogens of public health
importance including Staph. aureus, E. coli, Salmonella spp., Listeria spp.,
Aeromonas spp., Yersinia enterocolitica and Erysipelothrix spp. An
experimental part was applied to evaluate the best method used for cooking
of eggs at different temperatures for different times to determine the safety
of eggs for consumption. The obtained results of isolation revealed that Staph.
aureus recorded the highest percentage of contamination among all the
isolated pathogens specially from shell surfaces of all types of eggs.
Commercial Balady hen eggs were the best type and advised to be consumed.
Staph. aureus recovered from 23.3 , 13.3 and 10% of shell surfaces, shell
mixed with shell membranes and egg contents, respectively while, E. coli, S.
paratyphi, S. enteritidis, Y. enterocolitica and Erysipelothrix organisms were
failed to be detected in the examined Balady hen egg samples. Commercial
farm hen eggs came secondary to Balady hen eggs. Staph. aureus isolated
from both shell surfaces and egg contents with percentages of 23.3% and
13.3% from the shell mixed with shell membranes. S. enteritidis recorded high
rate of isolation from egg parts 16.7, 10 and 10%, respectively. E. coli, some of
Aeromonas spp. and Y. enterocolitica could be isolated from some egg parts
examined. S. paratyphi, S. gallinarium, Listeria spp. and Erysipelothrix spp.
failed to be detected from farm hen egg samples examined. Highest rate of
contamination was observed in commercial duck eggs. Staph. aureus was
recoverd from shell surfaces, shell mixed with shell membranes and egg
contents in 36.7, 30 and 33.3%, respectively. E. coli also recorded in high
percentages of infection in shell and shell mixed with shell membranes (13.3
and 10%, respectively). Moreover, varying percentages of contamination by
Salmonella, Listeria and Aeromonas spp. were recorded in different parts of
duck egg samples examined, in addition to Y. enterocolitica which could be
Assiut Vet. Med. J. Vol. 54 No. 117 April 2008
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isolated from shell, shell mixed with shell membranes and egg contents in 10,
3.3 and 6.7 %, respectively. On the other hand, Erysipelothrix spp. failed to be
detected in all examined duck egg samples. Concerning the experimental part,
results showed that cooking of eggs by Omelet method at 163oC for 25
minutes is the best since non of the test organisms used could be detected.
Secondary, was the open frying method where S. enteritidis destroyed after 1
minute, and complete destruction of Staph. aureus and E. coli after 12
minutes. Boiling procedure for 7 and 12 minutes were adequate to destroy
Staph. aureus and S. enteritidis, respectively, while, E. coli still be alive. The
economic and public health importance of some pathogens that affect the
human health through consumption of eggs were discussed. Likewise,
suggestive measures for improving the quality of produced eggs and the
suitable procedure to cook eggs are given.