Two Iowa egg farms linked to a salmonella outbreak that has sickened thousands failed to follow their own safety plans, allowing rodents and other animals into poultry houses, U.S. Food and Drug Administration inspectors found.

The latest details come days after the FDA pinpointed a bacteria found in chicken feed at the two farms as a probable source of the outbreak, which prompted the recall of more than a half billion eggs.

During inspections conducted on August 19-26, officials found rodent holes and leaking manure at several locations run by Hillandale Farms of Iowa, and non-chicken feathers and live mice and flies at houses owned by Wright County Egg, according to reports posted on the FDA website.

The agency has asked the companies -- which the Centers for Disease Control and Prevention believe could be the source of about 1,470 reported salmonella-related illnesses -- to correct the problems, which violate the egg producers' safety plans.

Julie DeYoung, a spokeswoman for Hillandale Farms, said several of the reported problems have already been corrected and others had already been identified by the company. Wright County Egg could not be reached for comment.

Inspectors also observed employees failing to change protective clothing and clean equipment and found insufficient documentation at some plants.

The FDA does not announce enforcement actions before taking them, but could consider injunctions or criminal prosecutions, said Michael Taylor, FDA's deputy commissioner for foods.

We've made these observations because they are significant deviations from what should be happening, Taylor said.

FDA officials also said inspectors found salmonella in a water sample collected from a Hillandale Farms plant.

The sample came from spent egg-wash water, or water used to wash the exterior of eggs traveling down conveyor belts to the packing facility, said Jeff Farrar, FDA's associate commissioner for food protection.

DeYoung said eggs at Hillandale are also rinsed with water containing chlorine as an additional step to kill bacteria.

The massive recall came weeks after a new FDA rule tightening safety rules for egg producers and renewed calls for the Senate to pass legislation that would toughen the FDA's food regulation authority.

Infrequent inspections are not sufficient to force companies to comply with safety rules, Caroline Smith DeWaal, of advocacy group The Center for Science in the Public Interest, said in a statement on Monday, citing violations at a peanut facility linked to salmonella last year.

The massive recall came weeks after a new FDA rule tightening safety rules for egg producers and renewed legislators' calls for the Senate to pass legislation that would toughen the FDA's food-regulation authority.

The outbreak could be linked to almost 2,400 reported cases of salmonella-related illnesses around the country since May 1, although CDC officials have said about 930 cases are reported each year during that time.

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