CHAPTER XXII. 



HEMOGLOBINOPHILIC BACILLI: KOCH-WEEKS, 

 MORAX-AXENFELD AND DUCREY BACILLI. 



BACILLUS INFLUENZA. 



BACILLUS INFLUENZA was isolated in pure culture and described by 

 Pfeiffer. 1 



Morphology. It is an extremely small bacillus, one of the smallest 

 known, measuring from 0.2 to 0.3 micron in diameter and from 0.5 

 to 1 micron in length. The ends are rounded and it occurs singly or 

 in pairs, rarely in short chains. The organism is non-motile, and no 

 flagella have been demonstrated. Spores and capsules are not pro- 

 duced. Ordinary anilin dyes do not color the organism readily, 

 but Pfeiffer 2 has shown that dilute carbol-fuchsin 3 stains it readily. 

 StaineoTwith methylene blue or dilute carbol-fuchsin, the ends of the 

 bacilli are colored somewhat more deeply than the centre, suggesting 

 a bipolar distribution of the cytoplasm similar to that exhibited by 

 the bacteria of the hemorrhagic septicemia group. The organism is 

 Gram-negative. 



Isolation and Culture. Bacillus influenzse is an obligately hemoglo- 

 binophilic organism; it does not grow outside the body in the absence 

 of hemoglobin, although the amount of this substance required to 

 encourage development may be so small in amount that it is invisible 

 to the eye. 4 The organism may be isolated from bronchial mucus 

 by Pfeiffer's method. The mucus is washed several times with sterile 

 water to remove extraneous bacteria, then spread upon blood agar 

 plates. Human, pigeon or rabbit blood added to neutral plain agar 

 creates a favorable medium for the bacillus. The colonies which 

 appear after twenty-four to forty-eight hours' incubation at 37 C. 

 are very minute, clear and colorless. They may require a lens for 

 their recognition. The hemoglobin is not visibly changed in appear- 

 ance and no hemolysis occurs. Massive cultures of influenza bacilli 



1 Deutsch. med. Wchnschr., 1892, No. 2. 



2 Ztschr. f. Hyg., 1893, xiii, 357. 



3 One part carbol-fuchsin, 9 parts water. 



*Ghon and Preyss, Centralbl. f. Bakt., 1902, xxxii, 90; 1904, xxxv, 531. 



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