B. Heterofermentative, producing considerable amounts of carbon dioxide, ethanol and acetic acid as well as lactic acid from carbohydrates. Genus IV. Leuconostoc, p. 531. II. Strictly anaerobic (one species becomes aerotolerant with repeated transfers). Genus V. Peptostreptococcus , p. 533. Genus I. Diplococcus Weichselbaum, 1886.* (Wiener med. Jahrb., 82, 1886, 483.) Dip.Io.coc'cus. Gr. adj. diplous double; Gr. noun coccus a grain, berry; M.L. mas.n. Diplococcus paired coccus. Cells usually in pairs, sometimes in chains. Young cells Gram-positive. Parasites, some- times growing poorl}^ or not at all on artificial media. Fermentative powers usually high, most strains producing acid from glucose, lactose, sucrose and inulin. The organisms in this genus are soluble in a 10 per cent bile solution. The type species is Diplococcus pneumoniae Weichselbaum. 1. Diplococcus pneumoniae Weichsel- baum, 1886. (Microbe septicemique du salive, Pasteur, Chamberland and Roux, Compt. rend. Acad. Sci., Paris, 92, 1881, 159; Micrococcus of rabbit septicemia, Sternberg, National Board of Health Bull., Washington, 2, 1881, 781; Coccus lanceole, Talamon, Communication k la Society ana- tom. de Paris, 58, 1883, 475; Weichselbaum, Wiener med. Jahrb., 82, 1886, 485; Pneu- moniemikrococcus or Pneumococcus, Fran- kel, Ztschr. f. klin. Medizin, 10, 1886, 402.) pneu.mo'ni.ae. Gr. noun pneumon the lungs; M.L. fem.n. pneumonia pneumonia; M.L. gen. noun pneumoniae of pneumonia. Common name: Pneumococcus. The organisms occur as oval or spherical forms typically in pairs, occasionally singly or in short chains, 0.5 to 1.25 microns. The distal ends of each pair of organisms tend to be pointed or lancet-shaped. Encapsu- lated. Non-motile. Young cells are Gram- positive. Gelatin stab: Filiform or beaded growth. No liquefaction. Infusion agar colonies: Small, trans- parent, grayish, entire. Elevation high, convex, glistening, mucoid to watery. On blood agar the colonies are elevated at the center with concentric elevations and depressions. Hemolysis usually slight but often marked in anaerobic culture; met- hemaglobin formation with green zone around colony. Beef heart infusion broth: Uniform tur- bidity with variable amount of sediment. Addition of glucose, serum, whole blood or ascitic fluid enhances growth. Meat extract media: Growth irregular, usually poor if any. Inulin serum water: Usually acid with coagulation. Litmus milk: Usually acid with coagula- tion. Potato: No growth. Whole bile or 10 per cent solutions of sodium taurocholate or sodium glycocholate added to actively growing broth cultures will dissolve the organisms. It is customary to use from 0.1 to 0.5 ml of bile for each 0.5 ml of culture. Aerobic, facultative. Optimum temperature, 37° C. Usually no growth between 18° and 22° C. Optimum initial pH, 7.8. Source: Sputum, blood and exudates in pneumonia; cerebrospinal fluid in menin- gitis; mastoiditis; otitis media; peritonitis; empyema; pericarditis; endocarditis; ar- thritis; saliva and secretions of respiratory tract in normal persons. Commonest cause of lobar pneumonia. Habitat : The respiratory tract of man and animals.
- Revised by Prof. E. G. D. Murray, McGill University, Montreal, P.Q., Canada, Sep-
tember, 1938; further revision by Lt. Col. Elliott S. Robinson, M.C., Washington, D. C, January, 1944.
