148 MEDICAL BACTERIOLOGY 



Resistance. In moist state bacillus mallei is killed in i hour at 8oC., in 

 the Arnold steam sterilizer and autoclave it is destroyed in i or 2 minutes. 

 Thorough drying rapidly attenuates and soon kills it. In the hot-air sterilizer 

 it is killed within i hour at i2oC. At room temperature, 5 per cent, phenol 

 solution kills it in less than 15 minutes; 1:1000 bichloride of mercury in less 

 than 45 minutes. Complete exposure to direct sunlight will kill it in several 

 days. This bacillus has been found alive and virulent after remaining 60 days 

 in a water trough. 



Toxin. Bacillus mallei produces an intracellular toxin, mallein, obtained 

 the same as tuberculin, and employed in the diagnosis of glanders in animals, 

 the same as tuberculin is employed in the diagnosis of tuberculosis in cattle; 

 with this exception at present mallein is usually dropped on the eye, not 

 injected subcutaneously. There is no extracellular toxin production. 



Pathogenesis. Infection in man is usually through an abrasion of the 

 skin, a nodule developing at the atrium of infection is rapidly surrounded by a 

 zone of intense inflammation. High fever, severe malaise, a general papular 

 eruption that becomes pustular frequently occurs in severe acute cases which 

 are often fatal in 2 or 3 weeks. 



Less acute cases and those terminating in recovery may not develop a 

 generalized eruption. Infections running a chronic course in man are marked 

 by enlargement of the lymphatic glands and vessels and are often fatal. 



Rabbits and guinea-pigs are susceptible to inoculation. 



Diagnosis. Laboratory diagnosis is based on microscopical and cultural 

 studies of the exudate from open lesions, or of fluid aspirated from enlarged 

 glands, or excised glands emulsified with normal salt solution, and the result 

 of guinea-pig inoculation. 



The exudate from open lesions usually contains organisms in addition to the 

 Glanders bacillus, and should be thoroughly cleansed and covered with a moist 

 aseptic dressing for several hours before specimen is removed for examination. 

 Suspected material is planted on potato medium. 



When inoculation test is to be made, exudates and superficial tissue apt to 

 be contaminated with other organisms are injected subcutaneously into a guinea- 

 pig. When nodules develop or the pig dies, under strict aseptic precautions, 

 a nodule is excised, placed in a glass mortar with several times its volume of 

 normal salt solution and emulsified. One or 2 cc. of this emulsion is injected 

 into the peritoneal cavity of a male guinea-pig. 



Subcutaneous nodules removed from patients are emulsified and injected 

 directly into the peritoneal cavity of a male guinea-pig. 



When injected this way, in pure culture, into male guinea-pigs, bacillus 

 mallei, frequently, but not always, causes a severe orchitis with enlargement 

 and suppuration. 



