It depends to some degree on the amount and duration of use.
If a soil has had fresh animal feces in it, you will want to dig it up to mix the feces well to dilute it in the soil.(Remove, with gloves, any clumps of solids). If the cat has used the site for a long time, you may need to remove the top foot of the soil and exchange it with soil from another area of your yard that doesn't have the feces or buy fresh soil. When growing vegetables, organic growers need to wait 90 days after applying manures to the soil before planting veggies to ensure no harmful bacteria will get on the produce. You don't have as much risk of the harmful bacteria getting on the produce if you grow vegetables that are taller and well removed from the soil (i.e. avoid crops like lettuce that will get soil splashed on them). You can also mulch around plants with 3-4 layers of newspapers, overlapping, and mulch on top of that, in order to prevent soil from splashing upwards. Chicken wire laid over a garden bed helps to keep cats off the soil. Once the plants are in the ground and growing you could put the wire around the base of the plants and on bare soil.