The bacteria responsible for causing nursing bottle caries are:

Streptococcus mutans is an important pathogen in the development of dental caries. The microorganisms are usually not detectable in the mouths of infants until the later stage of incisor emergence. The main source of S. mutans is usually the mother. Other microorganisms like Lactobacillus, Veillonella are also responsible for the nursing bottle dental caries.