Sugars and salts will tie up moisture. This means that the moisture is not available for microorganisms to use for growth. Syrups and honey are examples of foods which appear to have a lot of moisture but do not spoil without refrigeration because their moisture is bound by the high sugar concentration. Another example is catsup, which is high moisture but also contains enough acid to be safe at room temperature. Certain foods are involved repeatedly in cases of foodborne diseases.
Microorganisms are abundant in nature and the cause of most food-borne illness.
Bacteria are usually found on all agricultural and fishery products. Another major source of bacteria is people and animals including pets. In essence, the micro-organisms are almost everywhere. These microorganisms do not increase in size but increase in numbers. Limited numbers in food are not enough to cause illness.