A team from the University of Georgia, Ohio State University and North Carolina State University tested 300 organic and 400 conventional samples, which included floor droppings, feed sample and drinking water. The scientists concluded that the organic broiler (chickens raised for meat) farms had a 4.3% rate of salmonella prevalence, while the conventional farms rate was nearly seven times that at 28.8%.
Tom Philpott of Grist.com took a look at the study and explained that "39.7 percent of the salmonella found in the conventional birds had resistance to no fewer than six different antibiotics. None of the salmonella from the organic birds showed antibiotic resistance."
Philpott noted that the rules on organic chickens are somewhat subject to interpretation, but at the very least they must not be given any antibiotics or other "animal drugs," nor can there be any "animal slaughter byproducts" in the feed. Beyond that, organic standards may vary.