Med. Weter. 69 (6), 374-377, 2013

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Gondek M., Szkucik K., Bełkot Z.:
Presence of pathogenic microorganisms on the surface of eggs from different hen-housing systems
The purpose of the research was to determine the presence and frequency of pathogenic microorganisms of the genera Salmonella, Listeria, and Campylobacter, and of coagulase-positive staphylococci on the surface of consumer eggs from different hen-housing systems. The research material consisted of 120 eggs, comprising 30 eggs from each of four farms using different housing systems: the battery system, the deep-litter system, the free-range system, and the organic system. The eggs were collected into sterile bags in the henhouse directly after being laid, before being marked. The presence of microorganisms was established in accordance with Polskie Normy (Polish Standards). No Salmonella rods were detected on eggs from any of the four hen-housing systems. Microorganisms of the genus Campylobacter were found on 4 eggs (13.13%) from the deep-litter housing system and on 3 eggs (10%) from the free-range system. Only on the eggs from the battery system, no bacteria of the genus Listeria were detected. These bacteria were found on 3 eggs (10%) from the deep-litter system, but the presence of L. monocytogenes was confirmed on only one of the three eggs. In the case of the eggs from the free-range system, bacteria of the genus Listeria were present on 15 eggs (50%), 3 of which (10%) were polluted with L. monocytogenes. The same microorganisms were also detected on 14 eggs (46.7%) from the organic system, but none of them were L. monocytoges. All eggs examined, irrespective of the housing system, were polluted with coagulase-negative staphylococci, whereas coagulase-positive staphylococci were detected on a single egg from the free-range housing system only. The research demonstrated that human pathogens can be found on the surface of consumer eggs from any housing system. The housing system has a statistically significant influence on the degree of pollution with these microorganisms. The battery system, in which only coagulase-negative staphylococci were found, appears to be the safest in terms of the pollution of eggs with pathogenic microflora. The possibility of eggs being polluted with human pathogens makes it highly advisable for consumers to wash eggs directly before use.
Key words: eggs, laying hen, Salmonella, Listeria, Campylobacter, Staphylococcus.