Streptococcus pneumoniae laboratory tests

Overview
Depending on the nature of infection, an appropriate sample is collected for laboratory identification. Pneumococci are typically gram positive, cocci, seen in pairs or chains. When cultured on blood agar plates with added optochin antibiotic disk, they show alpha-hemolytic colonies and a clear zone of inhibition around the disk meaning they're sensitive to the antibiotic. Pneumococci are also bile soluble. Just like other streptococci, it's catalase negative. Quellung test to identify specific capsular polysaccharides may also be done.