Which of the following is the predominant flora of the mouth?: (A) Streptococcus mutans, (B) Lactobacillus, (C) Staphylococcus epidermidis, (D) E.coli
Answer is A. The eruption of teeth at 6 to 9 months of age leads to colonization by organisms such as Streptococcus mutans and S. sanguis, both a-hemolytic streptococci. An edentulous person loses a-hemolytic streptococci as normal flora. The predominant bacteria on the skin surface are S. epidermidis and Propionibacterium, an anaerobic diphtheroid.