Which microorganism is known to initiate the process of dental caries?

Streptococcus mutans is recognized as the primary microorganism involved in the initiation of dental caries, commonly referred to as tooth decay. This bacterium is particularly adept at adhering to the tooth surface and forming dental plaque. It metabolizes sugars from the diet, producing acid as a byproduct. This acid can then demineralize the enamel of the teeth, which is the first step in the development of dental caries.

In contrast, the other microorganisms listed are not primarily associated with the initiation of dental caries. Escherichia coli is mainly found in the intestines and is not a significant contributor to dental decay. Lactobacillus casei is more involved in the progression or later stages of caries rather than its initiation, while Staphylococcus aureus is typically associated with skin infections and other systemic illnesses rather than dental health. Therefore, the role of Streptococcus mutans is critical as it initiates the carious process, highlighting its importance in dental pathology.