This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Dental caries is caused by 
Select and explain. 
A. Streptococcus pyogenes, B. Streptococcus mutans, C. Enterococcus, D. Hemophilus Influenzae
B: Streptococcus mutans
Answer: B: Streptococcus mutans 
Explanation: Streptococcus mutans is an alpha Hemolytic streptococcus which is a pa of the normal flora of the oral cavity. This gram-positive coccus is commonly found in the mouth from where it can spread to cause dental caries or endocarditis in individuals with risk factors(dental extraction in individuals with damaged hea valves). The bacteria has a polysaccharide coat that allows it to stick to teeth and also to the damaged hea valves. It produces acid from sugar in saliva and this promotes erosion of tooth enamel. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 221