I Q2 BACTERIA 



ton, or a stick, is rubbed over the false membrane, or throat, and 

 then over the serum; the latter is incubated, and the culture ex- 

 amined after eight or twelve hours, by staining with Loffler's blue. 

 If curved, clubbed, irregularly stained bacilli are found, especially 

 if they contain dark polar granules, and are generally uneven in 

 size and bizarre, it may be safely considered that they are diphtheria 

 bacilli. Gram's stain may be needed to confirm the diagnosis 

 occasionally, or it may be necessary to inoculate guinea pigs. 



PSEUDO-DIPHTHERIA BACILLUS. 



CorynebacteriumPseudo-diphtheriticum. 



Pseudo-diphtheria Bacillus. (Hoffmann.) 



Morphology and Stains. This bacillus resembles the diph- 

 theria bacillus. The rods, however, are shorter and thicker; other- 

 wise, it stains like the true bacillus, but not by Neisser's method. 



Culture. On glycerine agar the growth becomes diffuse, 

 spreading from the line of inoculation in a grayish-yellowish pasty 

 expanse. It grows well on gelatine. In bouillon it forms a 

 denser and more luxuriant growth than the true bacillus. 



Habitat. It is found in healthy throats and conjunctivas. 



Pathogenesis. It is non-pathogenic for guinea pigs. It can 

 produce abscesses, nasal sinusitis and otitis media, and even endo- 

 carditis in man. 



Diagnosis. It can be differentiated from the true bacillus by 



1. Being non-pathogenic. 



2. Not exhibiting polar granules with Neisser's stain. 



3. Not producing acids in certain carbohydrate media. 

 Bacillus xerosis is a pseudo- diphtheria organism found on the 



normal conjunctiva. It is not thought to possess any virulence. 



TUBERCLE BACILLUS. 



Mycobacterium Tuberculosis. 



Bacillus tuberculosis. (Fig. 68.) 

 Tubercle bacillus. 



