Is there any chance that ongoing genetic modification has made them more susceptible to picking up/carrying salmonella?
Before this idea is poo-pooed - why have we not had such cases before? We have been eating tomatoes of all varieties for hundreds of years and only now where genetically modified strains are becoming more and more available does this problem arise.

Take a moment and think about it. If we continually tamper with the genetic make up of the food we eat it is only going to be so long before disease and defects start to affect us.

GM crops may enable farmers to grow food where they couldn't before, or make them more drought tolerant or make the fruits bigger and more uniform, blahdy blahdy blah, but at what cost to the consumer - should we be tampering with nature so much?

You are what you eat.