426 HEMOGLOBINOPHILIC BACILLI 



blood agar. The organism is often referred to as the Streptobacillus 

 of Ducrey. 



Morphology. The bacillus of Ducrey is a small bacillus, measuring 

 about 0.5 micron in diameter and from 1 to 2 microns in length. It 

 occurs characteristically both in chancroids and in culture in chains 

 of considerable length. Frequently these streptobacilli are found in 

 dense masses. The organism stains with ordinary anilin dyes; usually 

 the stain is more intense at the ends of the rod, the centre being nearly 

 devoid of color. This gives the organism a diplococcoid appearance. 

 It is Gram-negative. 



Isolation and Culture. The Ducrey bacillus does not grow upon 

 ordinary media, but cultures may be obtained by the method of 

 Davis, 1 which consists essentially in sterilizing the skin over an 

 unbroken bubo and aspirating the contents with a hypodermic needle 

 which has been maintained at body temperature. 2 The material is 

 introduced directly upon the surface of blood agar. 3 If the ulcers or 

 buboes have opened, they may be cleaned with sterile gauze, dried, 

 then painted with tincture of iodin and covered with sterile gauze. 

 Inoculations upon blood agar are made from the pus which collects 

 under the gauze within twenty-four hours. 



The colonies are usually visible after twenty-four hours' incubation 

 at 37 C. They appear as raised, shining, grayish droplets with a 

 pearly lustre. They die out rapidly at room temperature, but may be 

 kept alive at body temperature for some days. The colonies are 

 removed from the medium with some difficulty, for they tend to slip 

 away from the platinum needle. Subcultures tend to increase some- 

 what in luxuriance of growth, and by frequent transfer the organism 

 may be kept alive for weeks provided the growths are maintained at 

 37 C. 



The bacillus of Ducrey is an aerobic organism which is not resistant 

 to drying. The pus becomes non-infective after one or two days' 

 desiccation. Weak antiseptics quickly destroy it. 



The products of growth are unknown. 



Pathogenesis. It is non-pathogenic for ordinary laboratory animals. 

 Tomasczewski 4 claims to have reproduced a chancroid in a monkey 



1 Jour. Med. Research, 1893, ix, 401. 



2 Both the syringe and the blood agar should be warmed to body temperature before 

 use, because the organism rapidly loses its viability at room temperature. 



3 Blood agar for this purpose is prepared by adding defibrinated human or rabbit 

 blood to agar; the medium is heated to 56-60 C. for thirty minutes to destroy natural 

 bactericidal substances, and incubated for twenty-four hours to insure sterility. 



4 Deutsch. med. Wchnschr., 1903, No. 26. 



