Optochin

Optochin (or ethylhydrocupreine) is a chemical used in cell culture techniques for the presumptive identification of Streptococcus pneumoniae, which is optochin-sensitive, from other alpha-hemolytic streptococci such as Streptococcus viridans which are resistant. A common mnemonic is "OVRPS" (Optochin - Viridans Resistant, Pneumoniae Sensitive). Or "VROPS" (Viridans Resistant Optochin, Pneumoniae Sensitive)