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, how- 

 ever, usually negative.) 



Do not grow on ordinary media. Require blood agar (haemophilia bacteria), serum 

 agar, or blood-serum. 



Minute dew-drop colonies. 



1. Influenza bacillus. Requires blood media. 



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



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

 cultivate. 



4. Morax diplobacillus of conjunctivitis. Grows well and produces little pits 

 of liquefaction in Loffler's blood-serum. 



5. Bordet-Gengou bacillus of whooping-cough. Does not grow on Loffler's 

 serum. Requires blood or ascitic fluid agar. 



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

 chains. 



Grow well on ordinary media. 



I. Cultures in litmus milk. PINK. 



A. Nonmotile. 



Lactis aerogenes group. B. lactis aerogenes. 



Produce gas in glucose, lactose, and saccharose. No liquefaction of gelatin. 

 Short, stubby bacteria, often showing capsules. Intermediate between 

 the colon and Friedlander group. 



B. Motile. 



1. No nliquef action of gelatin. 



a. B. coli group. Coagulation of milk. No subsequent peptonization. 

 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. Haemorrhagic septicaemia group. These are oval bacilli with tendency 

 to bipolar staining. 



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