XVI. 



BACTERIA IN INFECTIOUS DISEASES. 



IN the present chapter we shall give a brief account of the re- 

 searches which have been made relating to the presence of bacteria 

 in various infectious diseases of man and the lower animals, and in 

 localized infections which have been supposed, on more or less satis- 

 factory evidence, to be due to their presence. For convenience of 

 reference we shall arrange these diseases in alphabetical order. 



ABSCESSES. 



The bacteria principally concerned in the causation of acute abscesses are : 

 Staphylococcus pyogenes aureus (No. 1), Staphylococcus pyogenes albus 

 (No. 2), and Streptococcus pyogenes (No. 5). For details, see Sec. IV. The 

 following species have also been found in acute abscesses, sometimes in 

 pure culture : Staphylococcus pyogenes citreus (No. 3), Micrococcus tetra- 

 genus (No. 18), Micrococcus pneumonia) crouposje (No. 8), Bacillus coli 

 communis (No. 89), Bacillus typhi abdominalis (No. 46), Bacillus pyogenes 

 fcetidus (No. 72) obtained from an abscess near the anus by Passet, Bacil- 

 lus pyogenes fcetidus liquefaciens, from a brain abscess following otitis media, 

 by Lanz. Passet also found in two abscesses out of thirty-three examined a 

 micrococcus named by him Micrococcus cereus albus, and in a single case 

 his Micrococcus cereus flavus. 



Recent researches show that next to the micrococci mentioned above as 

 commonly found in the pus of acute abscesses (Nos. 1, 2, 5). The micrococ- 

 cus of croupous pneumonia, the colon bacillus, and the bacillus of typhoid 

 fever are most frequently present the last mentioned in abscesses follow- 

 ing typhoid fever. In the so-called "cold" abscesses, due to tubercular in- 

 fection of glands, the tubercle bacillus is usually the only microorganism 

 present. 



See also Bubo, Mastitis, Otitis Media. 



ACNE. 



Hodara (1894) finds in the pustules of acne a small bacillus (No. 175) which 

 he believes to be the cause of the disease. It is said to be found at the base 

 and central portion of the comedones, while cocci and flask-shaped bacilli 

 are found in the superficial portion. In pseudo-acne pustules this bacillus 

 was not found. 



ACNE CONTAGIOSA OF HORSES. 



Dieckerhoff and Grawitz believe the cause of ' * acne contagiosa " in horses 

 to be a bacillus described by them (No. 141). 



