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 sensitive to 

 desiccation. 



ANILIN DYES. Stain with some difficulty. Loffler's methylene blue 

 and carbolic fuchsin 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 defibrinated 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 homogeneous. Later on, the middle of the col- 

 ony may show a yellowish 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 hamatogen-agar. 



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

 2-3 weeks. 



Somllon.'Blood must be added to the medium which, moreover, must be shallow. 

 Delicate white floccules 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. Optimum 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 conjunctivitidis, 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. 



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