132 

 BACILLUS TUBERCULOSIS. Koch. (1882). 



TUBERCLE BACILLUS. 



Origin. In tuberculosis of mammals. Lupus vulgaris. The 

 bacillus, present in chicken tuberculosis is distinct from that in 

 mammals. 



Form. Very narrow, rather long rods which are smaller than 

 the diameter of a red blood cell. The ends are distinctly rounded 

 and the bacillus itself may be straight or more frequently is slightly 

 bent or nicked. Occurs usually single but may form short threads 

 of 3-6 cells. In the sputum, tissues, etc., is" frequently found in 

 small bunches. 



Motility. Has no motion. 



Sporulation. Frequently shows a number of bright bodies 

 within the cell, but these cannot be considered as true spores. 

 .The bacillus itself possesses a relatively high power of resistance to 

 heat, desiccation, acids, putref action, etc. 



Anilm Dyes Stains very slowly and difficultly with simple 

 anilin dyes; readily with hot carbolic-fuchsine, or anilin-water 

 fuchsiue or gentian violet. When once stained it is difficult to 

 decolor, whereas ordinary bacteria do so readily. Specimens from 

 sputum and tissues can therefore be readily double stained dis- 

 tinction from all known bacteria, except the leprosy bacillus. Can 

 be stained by Gram's method. 



Growth. Takes place very slowly, requiring usually several 

 weeks to become clearly visible. Furthermore, a special tempera- 

 ture, at or near that of the body, and special media as blood-serum 

 or glycerine-agar, etc., are necessary. 



Plntes .No growth has been obtained on plates. Colonies can be readily 

 obtained by making successive streaks on glycerine-agar or blood-serum. 

 Colonies obtained direct from the sputum are round, white, opaque, and raised, 

 resembling colonies of white yeast. On subsequent culture the colonies are 

 dry, grayish scales. Under the microscope they appear as interwoven, 

 twisted strands of threads. 



Stick Cultures. Can be obtained on glycerine-agav. Growth restricted 

 to the upper part of the tube. It spreads over the surface as a thick, raised 

 plaque which at first is white, but later becomes yellowish. 



Streak Cultures.- On glycerine agar or blood-serum eventually develops 

 an abundant dry, granular, raised growth, which at first is grayish, but later 

 takes on a light yellow tinge. Similar growths develop on potatoes. 



Jiouill on. Grows well, especia'ly on the surface in bouillon which con- 

 tains the usual amount of glycerine, 5-6 per cent. Such bouillon cultures, 

 filtered and concentrated, constitute the so-called tuberculin. 



Oxygen requirements. Free access of oxygen necessary for 

 growth. Is a facultative anaerobe (FHAENKEL). 



Temperature. The optimum is about 37-39C. Slight varia- 

 tions above or below this stop the growth. It cannot, therefore, 

 grow at ordinary temperatures. 



Behavior to Gelatin. No growth. 



Attenuation. Slight attenuation probably does result with 

 age, but otherwise it has not been positively demonstrated. 



Pathogeneais. Man, monkeys, cattle', guinea-pigs, field mice, 

 rabbits, and cats are susceptible. White mice, rats, and dogs are 

 somewhat insusceptible. Chickens are immune. Inoculation of 

 pure cultures produces in susceptible animals tuberculosis. The 

 formation of tubercles and of giant cells. The bacilli may be very 

 abundant, at other times are scarce and difficult to find. 



Infection Takes place most frequently along the respiratory 

 tract Inhalation tuberculosis. May occur tlirough wounds Inocu- 

 lation tuberculosis, and also through food Intestinal tuberculosis. 

 Placental infection. 



