A patient presents with signs of pneumonia. The bacterium obtained from sputum was a gram-positive cocci which showed alpha hemolysis on sheep agar. Which of the following test will help to confirm the diagnosis?
S. pneumoniae, however, differs from streptococci in its morphology (by having a specific polysaccharide capsule), bile solubility, and optochin sensitivity.

S. pneumoniae produces an autolytic enzyme amidase, which solubilizes the peptidoglycan of the cell wall; hence in old cultures, typical draughtsman colonies are formed. This autolytic activity can be augmented by surface active agents, such as bile and bile salts.
Bile solubility is a constant feature of pneumococci, and is positive in all the capsulated and some noncapsulated variants.
Pneumococci are catalase and oxidase negative.

Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page:194-95
Bile solubility
Coagulase test
Bacitracin test
CAMP test