CHAPTER VII.^ 



STUDY AND IDENTIFICATION OF BACTERIA. MYCO- 

 BACTERIA AND CORYNEBACTERIA. KEY AND NOTES. 



Key for Bacilli. Having branching characteristics, as shown by 

 parallelism, branching, curving forms, V-shapes, clubbing at ends, 

 segmental staining, etc. 



Acid-fast. Mycobacterium. { 



I. Grow rapidly on ordinary media at room temperature. 



Examples: Timothy grass bacillus of Moeller (B. phlei). 



Mist bacillus. Butter bacilli as reported by (i) Rabino- 

 witsch and (2) Petri. 



II. Only grow at about incubator temperature. Scanty growth or none at all 

 on ordinary media. Media of preference are: (a) solidified blood- serum, 

 (b) glycerin agar and (c) glycerin potato. 



1. Cultures fairly moist, luxuriant and flat. Op. temp. 43 C. 

 a. Bacillus of avian tuberculosis. 



2. Cultures scanty, wrinkled and dry. Appear in 10 to 14 days. Op 

 temp. 38 C. Bacilli longer, narrower and more beaded. 



a. Bacillus of human tuberculosis. 



Cultures as above, but even more scanty. Bacilli shorter, thicker, 

 more even in staining and more regular in size. 



b. Bovine tubercle bacilli. 



3. Very difficult to cultivate (Czaplewski). 

 Smegma bacilli of various animals. 



III. Noncultivable (at present). 



i. B. leprae. Found chiefly in nasal mucus and in juice from lepra tuber- 

 cles. Less often in nerve leprosy. 



Nonacid-fast. Corvnebac.eriun, { %?%?** ^ 



I. Do not stain by Gram's method. 



i. B. mallei (Glanders). Characteristic culture is that on potato. 

 Growth-like layer of honey by third day. Becomes darker in color, 

 until on eighth day is reddish-brown or opaque with greenish-yellow 

 margin. 



II. Gram positive. 



1. Very luxuriant growth on ordinary media. Colonies often yellow to 

 brownish. B. pseudodiphtheriae. Shorter, thicker and stain uniformly. 



2. Moderate growth on ordinary media. B. diphtherias. Best media are 

 blood-serum (LofSer's) or glycerin agar. Has metachromatic granules 

 at poles. 



3. Scanty and slow growth on nutrient media. B. xerosis. 



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