CHAPTER XIV 



BACILLUS OF INFLUENZA, KOCH-WEEK'S BACILLUS, AND 

 BOKDET-GENGOU BACILLUS 



The bacillus of influenza occurs- in the mouth or throat of some healthy 

 persons, in the saliva and sputum of influenza patients and in the droplets of 

 mucus expelled with the breath. Outside the body, when dried, it dies in a 

 few hours. 



Morphology. The influenza bacillus is very small, 0.3 to 1.5 ju. 



Though usually rod-shaped, occasionally they resemble pneumococci, except 

 that no capsule is possessed by the influenza bacillus. 



Arrangement is irregular. 



Bacillus influenza is non-motile and Gram negative. 



Growth. The bacillus of influenza or Pfeiffer's bacillus is an obligate 

 aerobic organism that grows at temperatures between 26C. and 42C., best at 

 37C. It requires the presence of hemoglobin for cultivation, does not grow on 

 plain bouillon, agar or gelatin, poorly on blood-serum bouillon or serum-hemo- 

 globin bouillon. Blood-smeared agar is the best medium for its growth. On 

 this medium at 37C., discrete colonies develop in 18 to 24 hours. Many of 

 them are only visible when examined microscopically, some are pin-point size. 

 They are round, dewdrop-like, do not coalesce and cultures die out in about a 

 week unless transplanted. Growth is enhanced by cultivation in symbiosis with 

 staphylococcus aureus and colonies pin-point to pin-head in size develop. 

 Spores are not formed. 



Resistance. The bacillus of influenza is very perishable outside the body. 

 In sputum it may survive for several weeks, but usually it dies in several days. 

 Drying kills it in a day or two, iooC. in hot-air sterilizer kills it in less than ^ 

 hour. Moist heat at 5oC. kills in less than % hour. Chemical germicides in 

 very weak solutions rapidly destroy it. 



Toxin. The influenza bacillus produces an intracellular toxin. 



Agglutinins are not found in the blood of infected patients and experi- 

 mentally, agglutinin production is irregular, not constant, and never very strong. 



Complement fixation tests are not employed in the identification of this 

 organism. 



Pathogenesis. The influenza bacillus is the exciting cause of some cases of 

 coryza and influenza, occasionally it is the cause of pneumqnia and meningitis. 

 Bacillus of influenza infections occur sporadically, in epidemics and pandemics. 

 In some cases the organism is present in the blood stream. 



Guinea-pigs are immune to this organism. Rabbits and white mice die of 

 septicemia following massive intraperitoneal inoculations. The pathogenicity 



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