Looks like their feed is a possible culprit...
"Feed found at Wright County Egg in Iowa tested positive for salmonella, FDA officials said at a joint news conference with the Centers for Disease Control and Prevention. Salmonella also was found in walkways and manure at Wright County Egg, as well as in ingredients used in the feed. The samples of the salmonella were a genetic match to the salmonella that has made many people sick, officials said."
http://articles.latimes.com/2010/aug/26/nation/la-na-eggs-fda-20100827
"Feed found at Wright County Egg in Iowa tested positive for salmonella, FDA officials said at a joint news conference with the Centers for Disease Control and Prevention. Salmonella also was found in walkways and manure at Wright County Egg, as well as in ingredients used in the feed. The samples of the salmonella were a genetic match to the salmonella that has made many people sick, officials said."
http://articles.latimes.com/2010/aug/26/nation/la-na-eggs-fda-20100827