Skin Reactions with B. Typhosus Filtrate.

Abstract

For several years we have been studying skin reactions produced by a variety of bacterial filtrates in healthy persons, and in patients with different diseases. The recent typhoid epidemic in Montreal seemed to offer an unusual opportunity for further observations on the result of skin reactions with typhoid filtrates in typhoid fever patients. Through the courtesy of Dr. Ralph Lynch, of the Montreal General Hospital, observations were made on skin reactions of 22 typhoid patients in different stages of the disease. Intracutaneous tests with typhoid filtrates were also observed in other groups; for example, those who had no history of typhoid fever or of antityphoid vaccination, vaccinated persons, patients with other diseases, and 4 typhoid patients in Chicago.

After preliminary tests, the following technic was adopted: The typhoid bacillus employed in the test was the Rawling's strain. The medium used for the bacterial culture was a sugar-free, beef infusion broth 1% peptone, pH 7.4, to which was added 0.1% dextrose; the inoculated broth was incubated for 72 hours; then filtered through a Berkefeld filter and cultured for sterility. One:100 dilution, and in most instances 1:500 dilution in 0.1 cc. amount was injected intradermally in skin of forearm. Uninoculated broth, incubated and filtered in similar manner to the inoculated broth was used for control skin tests. Positive skin reactions appeared within 18 to 24 hours and persisted for at least 48 hours. A strongly positive skin reaction had an elevated, dark red, indurated center at least 2 cm. in diameter, frequently surrounded by a less definite halo of 2 to 3 cm. The severe reactions lasted from 48 hours to a week, then became pigmented, and frequently there was a slight desquamation. In only 2 instances were there systemic reactions.