510 PATHOGENIC MICROORGANISMS 



Gelatin is not liquefied. 

 Milk is coagulated. 



Upon potato, there is a thick yellowish growth. 

 Upon dextrose media, there is acid formation, but no gas. 

 The bacillus forms no indol in pepton solutions. 

 Pathogenicity. Corneal ulcers have been produced by inocula- 

 tion of guinea-pigs. 



/ BACILLUS OF DUCREY 



The soft chancre,- or chancroid, is an acute inflammatory, de- 

 structive lesion which occurs usually upon the genitals or the skin 

 surrounding the genitals. The infection is conveyed from one 

 individual to another by direct contact. It may, however, under 

 conditions of surgical manipulations, be transmitted indirectly by 

 means of dressings, towels, or instruments. 



The lesion begins usually as a small pustule which rapidly 

 ruptures, leaving an irregular ulcer with undermined edges and a 

 necrotic floor which spreads rapidly. It differs clinically from the 

 true or syphilitic chancre in the lack of induration and in its violent 

 inflammatory nature. Usually it leads to lymphatic swellings in the 

 groin which, later, give rise to abscesses, commonly spoken of as 

 "buboes." 



In the discharges from such lesions, Ducrey, 9 in 1889, was able 

 to demonstrate minute bacilli to which he attributed an etiological 

 relationship to the disease, both because of the regularity of their 

 presence in the lesions and the successful transference of the disease 

 by means of pus containing the microorganisms. 



Morphology and Staining. The Ducrey bacillus is an extremely 

 small bacillus, measuring from one to two micra in length and about 

 half a micron in thickness. It has a tendency to appear in short 

 chains and in parallel rows, but many of the microorganisms may 

 be seen irregularly grouped. It is not motile, possesses no flagella, 

 and does not form spores. 



Stained by the ordinary anilin dyes, it has a tendency to take the 

 color irregularly and to appear more deeply stained at the poles. By 

 the Gram method, it is decolorized. In tissue sections, it may be 

 demonstrated by Loeffler's methylene-blue method, and in such 

 preparations has been found within the granulation tissues forming 



* Ducrey, Monatschr. f. prakt. Dermal., 9, 1889. 



