I don't think manure would do it. I've eaten loads of veggies in my life that were (home)grown with manure, and I'm not the most thorough washer around. I don't wash mushrooms, for example, because the water spoils them. You could rub them a bit I guess, but frankly, cooking kills most things. O'course, you should be able to eat tomatoes raw/fresh and not worry about salmonella - and you say it was in spinach too? I was pretty sure it was a bacteria that only liked raw meat...