540 . PATHOGENIC MICROORGANISMS 



be stored at room temperature and transplantations done at intervals 

 not longer than four or five days. 



Biology. The bacillus is aerobic, growing in broth-blood mixtures 

 only upon the surface, hardly at all in agar stab cultures, and not at all 

 under completely anaerobic conditions. 



As it does not form spores, it is exceedingly sensitive to heat, desicca- 

 tion, and disinfectants. 1 Heating to 60 C. kills the bacilli in a few min- 

 utes. In dried sputum they die within one or two hours. They are 

 easily killed even by the weaker antiseptics. Upon culture media the 

 bacilli, if not transplanted, die within a week or less, the time depend- 

 ing to some extent upon the medium used. 



Pathogenicity. The relationship between the clinical disease known 

 as influenza or grippe and the Pfeiffer bacillus has been definitely estab- 

 lished by numerous investigators. 2 During epidemics, the bacilli are 

 found with much regularity in the nasal passages and bronchial secre- 

 tions of those afflicted with the malady. The organs most frequently 

 attacked in man are the upper respiratory passages and lungs. Here 

 the disease most frequently takes the form of a broncho- or lobular 

 pneumonia, and sections of the lung tissue of those who have died of the 

 infection show innumerable bacilli upon and within the mucosa of the 

 bronchioles. [Thin sections are stained for one-half to one hour in 

 dilute carbol fuchsin and are then dehydrated in slightly acid alcohol 

 (alcohol absolute J i, glacial acetic acid gtt. i-ij).] 



Clinically, influenzal broncho-pneumonias are not essentially dif- 

 ferent from those due to other microorganisms, and it must always 

 be left to the bacteriological examination to make the positive 

 diagnosis. Pulmonary influenzal infection is not infrequently followed 

 by abscess or gangrene of the lung, and occasionally develops into a 

 chronic interstitial process. The bacilli have also been found in the 

 middle ear, 3 in the meninges, 4 and in the brain and spinal cord. Bacilli 

 in the circulating blood have never been satisfactorily demonstrated, 

 although the general characters of the symptoms would suggest a septi- 

 cemia. The short incubation period 5 of the disease was involuntarily 

 determined by Kretz, who fell ill twenty-four hours after accidentally 

 breaking an agar plate of a pure culture which he was photographing. 



The bacilli are said to remain in the bronchial secretions of conval- 



l Kruse, in Fltigge, "Die Mikroorg.," Leipzig, 1896. 



2 Weichselbaum, Wien. klin. Woch., 32, 1892; Baumler, Munch, med. Woch., 

 1894; Huber, loc. cit. 



3 Kossell, Charite-Annalen, 1893. 4 Pfuhl, Berl. klin. Woch., xxxix, 1892. 

 5 Quoted from Tedesco, Cent. f. Bakt., xliii, 1907. 



