Colonies on Peptone Yeast Extract Agar (PYEA) are convex or umbonate, entire, matt,
buff colored, 1 mm in diameter, and difficult to emulsify. Growth temperature 23-42 ºC.
Can grow in pH 5.5-9.0. Hemolytic on horse blood. Serum liquefaction is negative.
Growth occurs on vitamin-free Casamino acids, peptone, yeast extract, and chocolate
agars. No growth occurs on Sabouraud dextrose agar, Czapek Dox agar, or PYEA
containing 40% bile, 0.1% potassium tellurite, or 10% NaCl.
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Phylum Proteobacteria, Class Betaproteobacteria, Order Neisseriales, Family Neisseriaceae, Genus Morococcus, Morococcus
cerebrosus
Long et al. 1981 - type species of the genus.
Gram-negative cocci, < 1 μm in diameter, grouped in tightly packed, mulberry-like
aggregates of 10
-20 cells, with adjacent sides often flattened. Nonmotile.
Endospores are not formed. Capsule is produced in sucrose-containing media.
Ecological niche unknown; originally isolated from a human brain abscess in Australia.
Susceptible to kanamycin (30 μg / disk), gentamicin (10 μg), streptomycin (10 μg), penicillin G (10 U), ampicillin (2 μg), erythromycin
(15 μg), nalidixic acid (30 μg), chloramphenicol (10 μg), and tetracycline (10 yg). Resistant to cloxacillin (5 μg) and methicillin
(5 μg).
Isolated from a human brain absces.
Pathogenic to mice (mice inoculated subcutaneously developed pyogenic lesions of varying sizes at the sites of inoculation and
showed lymph node involvement that persisted for more than 7 days).
  1. Long (P.A.), Sly (L.I.), Pham (A.V.) and Davis (G.H.G.): Characterization of Morococcus cerebrosus gen. nov., sp. nov. and
    comparison with Neisseria mucosa. Int. J. Syst. Bacteriol., 1981, 31, 294-301.
Positive results for catalase, DN-ase, H2S production from cysteine, iodine test, methyl red test, nitrate reduction to nitrite (and gas),
ornithine decarboxylase, oxidase, acid production from: fructose, glucose, maltose & sucrose.

Negative results for
arginine decarboxylase, casein hydrolysis, esculin hydrolysis, gelatin hydrolysis, glutamic acid decarboxylase,  
indole production, lecithinase, lysine decarboxylase, phosphatase, phenylalanine deaminase, starch hydrolysis, Tween 80
hydrolysis, urease,
acid production from: adonitol, arabinol, arabinose, cellobiose, dextrin, dulcitol, ethanol, erythritol, galactose,
glycerol, inositol,
inulin, lactose, mannose, melibiose, melezitose, mannitol, raffinose, rhamnose, ribose, salicin, sorbitol, sorbose,
starch, trehalose
& xylose. Citrate and malonate are not oxidized.
Morococcus cerebrosus
(c) Costin Stoica
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