Bacillus Influenzae, Pfeiffer (1892). 

 influenza; la grippe (Fr.). 



Origin. — In the greenish-yellow, purulent sputum of the disease; 

 present in masses in the nasal and bronchial -secretions; rarely in the 

 blood. In the early stage they are free, whereas later on they are in- 

 cluded within pus cells. 



Form. — Extremely small, rather plump rods; usually in pairs, very 

 rarely in threads. Involutions may be present in old cultures. Branch- 

 ing forms observed. The pseudo-influenza bacillus forms decidedly 

 larger rods which have a marked tendency to form threads. 



Motility. — It has no motion. 



Sporulation. — This has not been observed. It is very sensitiveto 

 desiccation. 



Anii.in dyes. — Stain with some dificulty. Loffler's methylene blue 

 and carbolic fiichsin are useful. Gram's method is not applicable. At 

 times, a bi-polar stain may be observed. 



Growth. — Is slight and requires a special medium (see below) and 

 the body temperature. Moreover, the culture should be transplanted 

 every 3 or 4 days. No growth on ordinary agar or serum. It is favored 

 by association with staphylococci. The addition of deflbrinated blood 

 to agar at 100° yields a good medium (Voges). 



Plates. — The colonies on agar-blood appear as isolated, minute, glassy drops which, 

 under the microscope, appear colorless and nom^eneous. Later on, the middle of the col- 

 ony may show a yellowisn or brownish color. They remain discrete and are usually so 

 small that a lens may be necessary to reveal them. 



Stab culture. — Very slight growth along the puncture in hSmatogen-agar. 



Streak culture. — Isolated, dew-like colonies on agar-blood. Vitality may persist for 

 2-3 weeks. 



Bouillon. — Blood must be added to the medium whichj moreover, must be shallow. 

 Delicate white jloccules form. The cultures retain their vitality for 2-3 weeks. In sterile 

 tap-water it dies out in about 24 hours. 



Oxygen requirements. — It appears to be anobligative aerobe. 



Temperature.— Ojitimum at 37°. May grow at 26 to 42°. 



Attenuation. — It is readily destroyed by mere desiccation, and is 

 even more sensitive in this respect than the cholera vibrio. ' 



Immunity. — Has not been established in guinea-pigs even after 

 prolonged treatment with living and dead cultures. 



Pathogenesis. — The effects on animals are not very characteris- 

 tic. Dead or living cultures injected intravenously in rabbits produce 

 fever, weakness and, at times, death; subcutaneously they induce ab- 

 scesses. Mice and guinea-pigs are less susceptible. Monkeys react 

 with a fever. The disease is primarily one of the respiratory pass- 

 ages from whence toxic products are absorbed. A somewhat similar 

 organism, Bacillus conjv/nctivitidis, is found in a catarrhal eye disease. 

 The latter is present in large numbers in the pus cells and can be 

 cultivated on agar-blood medium (Diplo-bacillus of Weeks). 



Diagnosis.— In the early stage a microscopical examination will 

 show large numbers of the characteristic rods. Otherwise it is neces- 

 sary to isolate the organism. This is done as follows: Agar is poured 

 into Petri dishes and allowed to solidify. Some human or rabbit 

 blood {Chap. XIV) is then spread over the surface of the plate. Fin- 

 ally the material itself, from a fresh acute case, is rubbed up in ster- 

 ile bouillon and is streaked over the plates, thus prepared, which are 

 then set aside at 37°. Obviously inclined agar tubes may be also em- 

 ployed. The material should also be streaked over the surface of 

 plain agar in which case failure to obtain growth would confirm the 

 nature of that which developed on agar-blood. 



360 



