1. Staphylococcus aureus Rosenbach, 1884. (Staphylococcus pyogenes aureus Rosen- bach, Mikroorganismen bei den Wund- infektionskrankheiten des Menschen, 1884, 19 ; Staphylococcus pyogenes albus Rosenbach, ibid., 21; Staphylococcus aiireus Rosenbach, ibid., 27; Staphylococcus albus Rosenbach, loc. cit.; Staphylococcus pyogenes citreus Passet, Aetiologie der eiterigen phlegmone des Menschen, Berlin, 1885, 9; Micrococcus aureus Zopf, Die Spaltpilze, 3 Aufl., 1885, 57; Micrococcus pyogenes Lehmann and Neu- mann, Bakt. Diag., 1 Aufl., 2, 1896, 165; Micrococcus citreus Migula, Syst. d. Bakt., S, 1900, 147; Micrococcus albus Buchanan, Veterinary Bact., 1911, 196; Staphylococcus citreus Bergey et al.. Manual, 1st ed., 1923, 55.) au're.us. L. adj. aureus golden. Spheres, 0.8 to 1.0 micron in diameter, occurring singly, in pairs, in short chains and in irregular clumps. Non-motile. Gram- positive. Chromogenesis : Typical Staphylococcus aureus cultures rather readily develop variants that grow as dirty white colonies. Such colonies quite frequently develop strains that again produce the tj'pical orange chromogenesis. On the other hand cultures occur which are white on original isolation. Such colonies usually do not develop orange variants although they are identical in other cultural characters and in their physiological characters with the orange strains. Some designate these white forms as Staphylococcus albus, as did Rosen- bach, and regard them as belonging to a separate species. Passet used the name Staphylococcus pyo- genes citreus for the organisms that produce the yellower (more lemon-colored) colonies. He distinguished these from the darker yellow (more orange-colored) colonies de- scribed by Rosenbach under the name Staphylococcus aureus. Passet secured his Staphylococcus citreus cultures from asepti- cally drawn pus. He reports that the yellow organisms were identical with the orange organisms except for the difference in chro- mogenesis. Later investigators have some- times reported other differences in charac- ters without referring back to Passet's original description, in which no such differ- ences in characters are noted. Gelatin stab: Saccate liquefaction with white to j-ellowish pellicle and white or yel- low to orange sediment. Agar colonies: Circular, smooth, orange to white, glistening, butj^rous, entire. Agar slant: Abundant, opaque, smooth, flat, moist, white to j'ellowish or orange growth. Broth: Turbid, becoming clear; yellowish ring and sediment. Litmus milk: Acid, coagulated. Acid from glucose, lactose, sucrose, man- nitol and glycerol. No acid from raffinose, salicin or inulin. Optically inactive or levo-rotatory lactic acid is produced (Orla- Jensen, The Lactic Acid Bacteria, 1919,81). Acetoin produced from glucose. Starch and esculin not hydrolyzed. Sodium hippurate usually hydrolyzed. Nitrites produced from nitrates. Amino acids are required as a source of nitrogen. Thiamin and nicotinic acid are required for growth. Does not utilize NH4H2PO4 as a source of nitrogen. Ammonia produced from peptone and arginine. Blood agar: Beta hemolysis normally pro- duced. Catalase-positive. Aerobic, facultatively anaerobic. Optimum temperature, 37° C. Grows at 10° and 45° C., these temperatures being very near the minimum and maximum tem- peratures respectively. Very salt tolerant, growing vigorously in media containing 10 per cent NaCl. Certain strains, under favorable condi- tions, produce not only exotoxins (hema- toxin, dermatoxin, lethal toxin, etc.) but also a potent enterotoxin which is a sig- nificant cause of food poisoning (Dolman and Wilson, Jour. Immunology, 35, 1938, 13). Pathogenic. Distinctive characters: Normally coagu- lase-positive (human or rabbit plasma). Ferments both glucose and mannitol under anaerobic conditions.
