**Identifying Streptococcus pneumoniae Using the Optochin Susceptibility Test** *S. pneumoniae* is a major cause of respiratory tract infections, and distinguishing it from other alpha-hemolytic streptococci is crucial in clinical diagnostics. The Optochin test offers a quick and reliable way to do that. In the video, I show: - Isolation of alpha-hemolytic colonies on blood agar - Placement of the Optochin disk - Key points for proper incubation **Why this matters:** Early and accurate identific