Pneumoccus – cultural characteristics
Pneumoccus bacteria demonstrating capsular swelling using quellung reaction
Pneumoccus grow only in enriched media. (blood agar, glucose broth)
- aerobes, facultative anaerobes
- optimal temperature – 37C (25-42C)
- optimal pH – 7.8 (6.5-8.3)
- increased growth in 5-10% CO2
Blood agar – 18 hours incubation
- small colonies (0.5-1mm)
- glistening
- dome shaped
- surrounded by green ring (alpha hemolysis similar to S.viridans)
Blood agar – prolonged incubation
- flat with raised edges
- central umbonation
- concentric rings formed (carrom coin appearance or Draughtsman appearance)
- mucoid colonies formed with capsule forming strains (types 3,7)
Blood agar – anaerobic conditions
- colonies surrounded by clear ring of hemolysis (beta hemolysis by oxygen labile hemolysin)
Liquid media (glucose broth)
- uniform turbidiy
Other features
- undergo autolysis due to intracellular enzymes
- autolysis increased by surface active agents such bile salts (chenodeoxy cholate), sodium lauryl sulphate
- autolysis not present in heat killed oranisms
