SPECIAL FORMS OF CONJUNCTIVAL INFECTION 165 



White Stapltylococci are fairly often mixed with them ; generally 

 they are of very low virulence, and in much smaller numbers 

 than the Diplobacilli. Pnenmococci, Streptococci, and Koch-Weeks 

 bacilli are more rarely found (Hoffmann, Zia, Duane, Hastings, and 

 others). Such cases are mixed infections, and .may not show the 

 peculiar clinical features of the disease. In the case of the last- 

 mentioned an acute catarrh usually occurs. 



If we take cultures daily, the admixed organisms are found to vary 

 greatly in number, and may at times quite disappear. This shows 

 the Diplobacilli to be the true pathogenic agents. If, however, the 

 conjunctivitis, and with it the numbers of the Diplobacilli, subsides, 

 the xerose bacilli and Stapltylococci become more obvious. 



Morphology of the Bacilli in Culture. 



The colonies on Loffler's blood-serum only show for the first or 

 second day Diplobacilli or Streptobacilli of varying size, such as are 

 seen in the pus. A free degeneration of the organisms soon 

 begins, with the formation of 

 variable, sometimes grotesque, 

 and very large involution forms. 

 As soon as the liquefaction of 

 the medium is well advanced, 

 we only see amongst masses of 

 unstained and dead organisms a 

 few double forms, chains, or fila- 

 ments of varying size. At this 

 stage the outlines of the organ- 

 isms stain more intensely than 

 their centres (see Fig. 23). 



On serum agar and in serum 

 bouillon their form and staining 

 are retained longer. 



Eapid decolorization occurs by Gram's stain. The organisms are 

 non-motile, and do not form spores. The same is true of the Petit 

 type. 



Only once did MacNab obtain a slight hypopyon-keratitis with the 

 Morax-Axenfeld bacillus. 



Resistance. 



The Diplobacillus dies out in a few days when on Loffler's serum 

 in the incubator. In the liquefied medium only necrotic forms 



FIG. 23. FORTY-EIGHT-HOUR CULTURE 



ON LOFFLER'S BLOOD-SERUM 



INVOLUTION FORMS. 



