6l8 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



Coccus forms sometimes appear and even short threads when grown on certain media; 

 e.g., potato. It decolorizes by Gram's method and is not easily stained by the aniline 

 dyes. This bacterium grows fairly well between 25 and 42 on potato, glycerin 

 agar, or blood serum. The guinea pig gives a reliable diagnosis by inoculation, giving 

 a diagnostic reaction in four or five days. Diagnosis may also be confirmed by the 

 agglutination test in dilution from i to 10 to i to 50 in from twenty minutes to three 

 hours (Moore) and by the complement fixation test. Satisfactorily stained in tissue sec- 

 tion by Kuehn's carbol-methylene blue. Its growth is limited at an upper range of about 

 42 and the culture is killed at 55 in about five minutes. Bact. mallei is difficult to 

 isolate by culture methods being a slow grower and easily lost beside faster growing 

 organisms. It can be better isolated by guinea-pig inoculation. In growth it is both 

 aerobic and aenasrobic. 



FIG. 106. Bacterium mallei. From pure culture on glycerin agar. Xiooo. (From 



Migula.) 



The virus escapes from the body in various ways. Elimination is 

 most common in morbid discharges from the nose, pharynx, trachea, and 

 in pus from farcy buds and abscesses. 



Bact. mallei may spread directly from the diseased animal to the sus- 

 ceptible animal, or the dissemination may be by way of intermediate 

 objects; e.g., troughs, feed boxes, water pails, etc., and perhaps also by 

 inhalation. 



In man, infection occurs usually by inoculation. Cases produced in 

 this way occasionally appear among laboratory workers. 



Bact. mallei is to be regarded as purely parasitic and limited in its 

 natural activities to the animal body. 



Bact. mallei is easily destroyed by a variety of unfavorable conditions. 

 It is destroyed by drying in fifteen to twenty days and is easily killed by 

 heat or antiseptics. 



