Consumer Reports has been measuring contamination in store-bought chickens since 1998. For the latest analysis, the had an outside lab test 382 chickens bought last spring from more than 100 supermarkets, gourmet- and natural-food stores, and mass merchandisers in 22 states. They tested three top brands—Foster Farms, Perdue, and Tyson—as well as 30 nonorganic store brands, nine organic store brands, and nine organic name brands. Five of the organic brands were labeled "air-chilled" (a slaughterhouse process in which carcasses are refrigerated and may be misted, rather than dunked in cold chlorinated water).

Among the findings:

1.  Campylobacter was in 62 percent of the chickens, salmonella was in 14 percent, and both bacteria were in 9 percent. Only 34 percent of the birds were clear of both pathogens. That’s double the percentage of clean birds we found in our 2007 report but far less than the 51 percent in our 2003 report.

2.  Among the cleanest overall were air-chilled broilers. About 40 percent harbored one or both pathogens. Eight Bell & Evans organic broilers, which are air chilled, were free of both, but our sample was too small to determine that all Bell & Evans broilers would be.

3.  Store-brand organic chickens had no salmonella at all, showing that it’s possible for chicken to arrive in stores without that bacterium riding along. But as our tests showed, banishing one bug doesn’t mean banishing both: 57 percent of those birds harbored campylobacter.

4.  The cleanest name-brand chickens were Perdue’s: 56 percent were free of both pathogens. This is the first time since we began testing chicken that one major brand has fared significantly better than others across the board.

5.  Most contaminated were Tyson and Foster Farms chickens. More than 80 percent tested positive for one or both pathogens.

6.  Among all brands and types of broilers tested, 68 percent of the salmonella and 60 percent of the campylobacter organisms we analyzed showed resistance to one or more antibiotics.

This video is also worth a watch: