BACILLUS PYOCYANEUS 413 
Prophylaxis in man consists essentially in preventing contact infec- 
tion with diseased animals or infected material, and particular care 
in preventing the inhalation of dust from hides or wool or cattle or 
sheep from countries where the disease is prevalent; this applies par- 
ticularly to South American, Moroccan and Russian hides and wool. 
BACILLUS PYOCYANEUS. 
Historical.— Surgeons for many years have noticed that occasional 
suppurating wounds discharge pus which stains bandages a green or 
green-blue color. Gessard^ demonstrated the specific organism, B. 
pyocyaneus, in pure culture and described it in considerable detail. 
Somewhat later Charrin^ studied the pathogenesis of the organism for 
rabbits (maladie pyocyanique) , setting forth clearly the importance 
of the bacillus as a disease-producing microorganism. 
Morphology.— B. pyocyaneus is a moderate-sized organism with 
rounded ends, usually occurring singly or in pairs, less commonly in 
short chains. The dimensions vary considerably even in the same 
culture; the diameter averages about 0.6 micron, although some 
bacilli measure but 0.3 micron and others as much as 1 micron. The 
length varies betwen 1.5 and 4 microns, the average being about 2 
microns. The organism is actively motile, and possesses a terminal 
polar flagellum (monotrichic flagellation). Capsules and spores have 
not been obser^•ed. Ordinary anilin dyes color the bacillus with mod- 
erate intensity, and it is Gram-negative, although the gentian violet 
is somewhat less readily removed by alcohol than from a majority 
of Gram-negative bacilli, as B. coli for example. 
Isolation and Culture.— The organism grows readily and rapidly 
upon ordinary artificial media, producing the characteristic pigments 
in the presence of oxygen. The colonies on agar are round and measure 
from 1 to 3 mm. in diameter after eighteen to twenty-four hours' 
incubation at 37° C, The growth spreads rapidly, and the pigment 
which becomes visible within eighteen hours dissolves in the medium 
imparting a blue-green color to it. Gelatin colonies are not charac- 
teristic in outline, but rapidly liquefy the medium, which becomes 
green. A turbidity is visible within eight hours in broth and a pellicle 
usually forms on the surface. A viscous, gray-brown sediment collects 
at the bottom of the tube, and an ammoniacal odor is noticeable even 
within twenty-four hours. The medium, particularly the upper layers 
in contact with oxygen, becomes blue-green. Milk is coagulated, 
the coagulum being slimy, and eventually partly or even completely 
dissolved; the medium, at first yellowish, becomes green, then blue, 
particularly in the upper layers. 
B. pyocyaneus is aerobic, facultatively anaerobic. The optimum 
temperature is 37° to 38° C; development is sluggish below 18° C. 
and practically ceases at 43° to 44° C. 
1 These de Paris, 1882, 2 La maladie pyocyanique, Paris, 1889. 
