Sputum sample is taken for diagnosis of URIs and LRIs. Option 1 Viridians Streptococci Gram-positive cocci in sho chains, Catalase negative and bile resistant Viridans streptococci are pa of a normal oral flora. cause of dental caries and subacute bacterial endocarditis. Option 2 Pneumococcus Gram-positive cocci in pairs, catalase negative and bile soluble form a-hemolytic colonies (Greenish colonies) on blood agar and optochin sensitive . responsible for the majority of community-acquired pneumonia. Gram staining of sputum = S. pneumoniae (gram positive diplococci with capsule) Optochin sensitivity = Pneumococcus on Blood agar showing a- Hemolysis (Paial hemolysis) with sensitivity to optochin disk. Option 3 S. aureus Gram-positive cocci in clusters, catalase positive coagulase positive Option 4 Brucella Gram-negative coccobacilli catalase positive and oxidase positive