Used in the selective isolation of Streptococcus mutans. TYCSB Agar is devised by Gold et al. (1) as a selective medium for Streptococcus mutans with bacitracin and sucrose. Streptococcusmutans is facultatively anaerobic, Gram-positive coccus-shaped bacterium commonly found in the human oral cavity. It is the primary causative agent of dental cavities (2). Conditions in the oral cavity are diverse and complex, frequently changing from one extreme to another. Thus, to survive in the oral cavity, S. mutans must tolerate rapidly harsh environmental fluctuations and exposure to various antimicrobial agents to survive (3). Tryptone and yeast extract in the medium provide nutrients essential for the growth of Streptococci. Sodium sulfite, sodium acetate, disodium phosphate, and sodium bicarbonate are sources of ions that simulate metabolism.