CHAPTER VIII. 



STUDY AND IDENTIFICATION OF BACTERIA. GRAM 

 NEGATIVE BACILLI. KEY AND NOTES. 



KEY to the recognition of nonspore-bearing, nonchromogenic, 

 non-Gram staining, nonbranching bacilli. 



(NOTE. Some books say that the proteus group is Gram positive. 

 It is, however, usually negative.) 



Do not grow on ordinary media. Require blood or serum agar (hemophilic 

 bacteria). Minute dew-drop colonies. 



1. Influenza bacillus. 



2. Koch- Weeks bacillus (conjunctivitis). Serum agar best medium. 



3. Muller's bacillus of trachoma. Like Koch- Weeks bacillus, but easier 

 to cultivate. 



4. Morax diplobacillus of conjunctivitis. Produces little pits of liquefac- 

 tion in serum. 



5. Pseudoinfluenza bacillus (whooping-cough?). 



6. Ducrey's bacillus (soft chancre). Requires almost pure blood. 

 Grow well on ordinary media. 



I. Cultures in litmus milk. PINK. 



A. Nonmotile. 



Lactis aerogenes group. B. lactis aerogenes. 



Produce gas in glucose lactose, or saccharose. No liquefaction of 



gelatin. Short, stubby bacteria. 



B. Motile. 



1. Nonliquef action of gelatin. 



a. B. coli group. Coagulation of milk. No subsequent pep- 

 tonization. Gas in glucose and lactose, none in saccharose. 

 Indol produced. Neutral red reduced. 



2. Liquefaction of gelatin. 



a. B. cloacae group. Gas in glucose, slight in lactose. Slow 

 coagulation of milk. Subsequent peptonization. 



II. Cultures in litmus milk. LILAC. 



A. Nonmotile bacilli. 



i. No gas generated in glucose or lactose bouillon. 



a. Hemorrhagic septicaemia group. These are oval bacilli with 

 tendency to bipolar staining. Examples: B. pestis, B. 

 suisepticus, B. cholera? gallinarum (chicken cholera). 



b. Dysentery gioup. Divided into two classes according as 

 mannite is acted on: 



Those not giving acid nonacid group (Shiga-Kruse) . 

 Those giving acid acid group (Flexner-Strong). 



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