A method of desensitization of allergy due to streptomycin with prednisone.

Lowell’ gave the incidence of allergy to streptomycin as 10 per cent. This high incidence is due to administration of the drug for long periods in tuberculosis. Most of the allergic reactions were not serious. There was no way of knowing whether a patient allergic to streptomycin could react again on re-administration. It might be assumed that he would. Houghton2 in England and Chakravarty3 in this country described two individual methods of desensitizing streptomycin allergy by ACTH and cortisone. This presentation discusses the method by which four patients who were allergic to streptomycin could tolerate this drug after desensitization with prednisone. When streptomycin with paraaminosalicylic acid (PAS) and/or isoniazid were given it was difficult to determine which of the drugs was causing allergy. For this purpose, an intradermal skin test with 10 mg. of streptomycin in 0.1 ml. of normal saline was given in one forearm. If there was induration of 5 to 10 mm. in diameter, the reaction was read as 1+, if 11 to 20 mm., it was 2+ and if more than 20 mm. or necrosis, it was 3+. If induration was less than 5 mm., it was read as doubtful and if no induration, but only erythema, it was considered negative. The skin test generally became positive within 12 to 24 (occasionally 48) hours. Simultaneously, with the streptomycin skin test in one forearm, purified protein derivative (PPD) No. 1 was given in the other. Generally, both streptomycin skin test and PPD tests were positive in allergic cases. Prednisone was started after the skin tests were known. The dosage varied in some cases, but the following dosage schedule was followed: For one week 50 mg. of prednisone was given orally each day. This was given in three divided doses. Then streptomycin skin test and the first dose of purified protein derivative No. 1 were repeated. Usually either