Free-range and organic farming: Eggshell contamination by mesophilic bacteria and unusual pathogens

The high incidence of foodborne illnesses caused by the consumption of eggs in industrialized countries is the main reason we decided to determine the microbial load on the surface of eggshells from free-range and organic farming. The objective was to compare which was better for ensuring the least possible health risk to the consumers, focusing on consumption of raw eggs by immune-compromised people. Bacteria come from the intestine of the animal or subsequent contamination. When eggs are cracked, bacteria from the shell reach the yolk and the albumen, and grow during manipulation and preservation, causing foodborne diseases in consumers. Microorganisms such as Salmonella, Listeria monocytogenes, Campylobacter, Enterobacteriaceae (including E. coli serotype O157: H7), Staphylococcus, Enterococcus, and mesophilic aerobic bacteria, were examined. The presence of bacteria on eggshells depends on hygienic conditions of the farming and packaging industries. Hygienic measures, such as strict cleaning and disinfection of surfaces in contact with eggs in packaging industries, would be a protective factor to minimize the contamination of eggshells. The total absence of pathogens demonstrates the relevance for human consumption of eggs coming from both free-range and organic farms, though YOPI (young, old, pregnant, or immune-compromised) people preferably should cook eggs in which bacteria contaminating the outer surface are killed.