Jacob and Helmbold1 isolated a gram-negative, anaerobic bacillus from twenty-five of twenty-eight patients with lichen planus. Semisolid dextrose-serum agar containing cubes of human tissue was the medium used. They stated that the serum must be inactivated at from 56 to 60 C. for a number of hours. The bacillus was not found in the skin of normal subjects or in that of a number of patients with other papular diseases, who were used as controls. Inoculation of human skin with the bacillus produced in a few instances lesions which clinically and histologically resembled lichen planus. Those authors described the bacillus as being somewhat polymorphic but resembling organisms of the colon-typhoid groups.
I should like to question the statement of resemblance to the colon-typhoid group, since organisms of that class are not anaerobic and since they grow freely on common mediums. Nevertheless, the results obtained by these authors were deemed
POSTMA C. EXPERIMENTS IN THE CULTURE OF THE ORGANISM OF LICHEN PLANUS BY JACOB AND HELMBOLD'S METHOD. Arch Derm Syphilol. 1937;36(4):836–837. doi:10.1001/archderm.1937.01480040153011
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