Diplococcus Pneumoniae is a minute, slightly lancet-shaped, non-motile, non-liquefying, optionally anaerobic diplococcus. Usually occurs in pairs, surrounded by a capsule that is not present when the organism is grown on culture medium.

Is found in the sputum of lobar pneumonia, in the exudate of meningitis, and sometimes in the saliva of healthy people. Is the common cause of croupous pneumonia, but is also found in inflammations of the serous membranes.

Stains

Ordinary methods and Gram's.

Fig. 83. - Gonococci in Urethral Pus (McFarland).

Culture

Grows best at 370 C, but has a range from 240 to 420 C. Will grow upon all culture media except potato. Gelatin plates (15 per cent, gelatin) give colonies that are small, round, circumscribed white points. On agar-agar the growth is almost invisible.