Microbial contamination in foods can come from many sources and the sanitary and hygiene conditions that prevail in food handling facilities can influence the microbial quality of food made there. Modern food processing plants incorporate many design features while setting up their production facilities with stainless equipment, contamination proof surfaces,"clean in place" (CIP) sanitation system, use of highly effective bactericidal and virucidal chemical agents, etc to ensure prime manufacturing conditions. But traditional food handling units find it very difficult to modernize their facilities due to investment constraints and they can pose some concerns to safety monitoring agencies as reflected by the recent report from the USDA sources.
"The microbial survey carried out by USDA's Agriculture Research Service (ARS) said that plywood nest run carts used to carry eggs can contain Enterobacteriaceae, a bacterial family that includes the human pathogens Salmonella and Shigella. These microbes are known to contaminate the shell egg processing environment, said the body, adding their presence in high levels in processing plants "can signal inadequate sanitation".
Of course egg is a highly nutritious food and has high potential for attracting pathogenic organisms with devastating consequences. Many traditional smaller poultry farms use primitive contraptions, a hang over from the past but their number may be low and as such the risks posed by them may not be serious. Probably USDA may ban use of such carts considering the present safety concerns faced by the American consumer.