BACTERIA IN SEPTIC WOUNDS 513 



and sometimes B. proteus, B. coli, B. pyocyaneus , etc. 

 The complete bacteriological study of such a wound may 

 therefore prove a very complicated matter. 



Among the numerous anaerobic organisms which can 

 be obtained from the wound or tissues in cases of gas 

 gangrene, only three play a predominant role in its 

 causation, viz. B. perfringens, the Vibrion septique and 

 B. cedematiens . Any one of these three organisms may by 

 itself cause gas gangrene, or any two of them, or all three, 

 may be the agents in some cases. In exceptional instances 

 B. fallax, B. aerofetidus, B. sporogenes and, possibly, 

 B. histolyticus may cause a condition of gas gangrene, 

 which is, however, relatively benign. 



In addition to these specific forms, other anaerobes and 

 aerobes are frequently associated with them, notably 

 B. putrificus (anaerobe) and B. coli, B. proteus, B. pyo- 

 cyaneus, streptococci and staphylococci (aerobes). These 

 may play a part in the causation of gas gangrene by 

 weakening the resistance of the tissues and paving the 

 way for the activity of the specific forms. B. coli and 

 B. proteus have both been incriminated as causes of gas 

 gangrene, but Weinberg and Seguin state that they have 

 never met with them alone. 



Fleming has shown that the aerobic forms may have 

 an important effect in determining anaerobic invasion, 

 either by exhausting the oxygen and thus facilitating 

 anaerobic growth, or by altering the serous exudation 

 in the wound and converting it into a pabulum well 

 adapted for the multiplication of the " sero-saprophytic " 

 anaerobes. 



All the organisms named are present in the soil, 

 particularly if manured, and the class of wounds 

 under consideration derives its infections from this 

 source. 



As regards the incidence of the gas gangrene organisms, 



M.B. 33 



