Philip Brasher of the Des Moines Register reports that the salmonella-in-Wright and Hillandale-eggs outbreak that has sickened at least 1,470 in the U.S. left officials at Costco Wholesale Corp. scratching their heads. How had inspectors for Costco, who looked over the northeast Iowa farm where the chain bought eggs, not noticed the rodent holes in the henhouses?

Craig Wilson, who oversees food safety for Costco, said, "There are a lot of guys going, ‘Hey, wait a minute. They’re finding stuff and our guys were there and they didn’t see it.’ "

Critics – and I was one of them — say many food-safety audits are designed to tell companies paying for them what they want to hear. The defunct Peanut Corp. of America had a glowing food safety audit from an outside firm before a 2008 salmonella outbreak in peanut butter that killed nine people and sickened more than 700.

U.S. Department of Agriculture inspectors also missed the problems at Hillandale as well as at Wright County Egg, a producer that recalled 380 million eggs and supplied Hillandale with hens and feed.

The USDA employees, whose main job is to grade eggs on their condition and catch defects, don’t check henhouses or look into farms’ salmonella-prevention programs, a job the USDA leaves to the Food and Drug Administration.

The USDA employees do inspect conditions in packing facilities for companies that request and pay for the service. The packing facilities at Hillandale in West Union and at four more farms operated by Wright County Egg had all been audited by the USDA in 2009 or this year and received stellar marks – grades of 97 to 99 percent.

Several customers of R.W. Sauder Inc., an egg producer in Pennsylvania, have told the company they plan to add salmonella-prevention measures to their egg specifications, said Paul Sauder, the firm’s president. Those buyers include a large supermarket chain and food service company, whom Sauder declined to name.

Buyers "had the perception that as long as the eggs were USDA-inspected, all eggs were equal. There is renewed awareness now," he said.

Salmonella in eggs is not new.