1 68 BACTERIA 



TYPHOID BACILLUS 



Bacterium Typhi. Eberth. 



Bacillus Typhosus 



Typhoid Bacillus (Fig. 46). 



A most important pathogenic organism which causes typhoid 

 fever. 



Morphology and Stains. Generally short plump rods i to 3/4 

 long, and .6 to .8/x broad. Forms long threads in cultures, 

 especially on potatoes. Polar metachromatic 

 bodies are sometimes seen as are unstained 

 areas when alkaline methylene blue is used. 

 The rod is flagellated (peritrichous) ; con- 

 tains no spores; exhibits pleomorphic and 

 involution forms; is actively motile, and 

 stains with all the basic aniline dyes, but 



ella. (Kolle and Vital Resistance. The thermal death- 



Wassermann.) point ig 6Q o c ^ ten tQ fifteen minutes> Re _ 



mains alive in ice for three months; even the temperature of 

 liquid air does not destroy it at once. In distilled water it lives 

 for months, but if other saprophytic bacteria are associated 

 with it, however, it quickly dies. Does not resist drying or 

 chemicals, except carbolic acid, towards which it exhibits a 

 tolerance. Sunlight kills it in an hour. 



Habitat. It never exists in nature, except where water or soil 

 has been contaminated by fasces or urine. It may multiply in 

 potable waters, in milk, and the juices of oysters. 



Chemical Activities. Does not produce proteolytic enzymes; 

 forms H 2 S, but will not ferment the sugars with gas formation. 

 Does not yield indol or nitrites. Produces levorotatory lactic 

 acid. Its toxin is all contained within the bacterial cell (endo- 

 toxins) and is not water-soluble. This toxin is manifested by 

 injecting washed and killed bacilli into animals, or by freezing the 



