Poisoning caused by Staph-infected foods. This is a dangerous infection that can randomly turn out mild or potentially fatal, even among a group of people who have eaten the same infected food. The first symptoms will be stomach cramps, vomiting, or diarrhea. As the infection progresses, blood pressure will inevitably fall, and intense and life-threatening dehydration will occur. Food poisoning is caused by Streptococcus aureus, and generally affects meat, dairy and poultry products that are either raw, badly cooked, or which have been allowed to spoil slightly.