Hypersensitivity to trimethoprim

Abstract

We present two patients who experienced life-threatening immediate reactions and one patient who developed generalized urticaria following oral administration of trimethoprim (TMP) and sulfamethoxazole (SMX) combination. Skin prick tests with TMP were positive in the three patients. No patients reacted to skin prick tests with SMX. No significant levels of IgE antibodies to TMP were found by RAST in the serum of the patients. Normal subjects used as controls did not react to any of these tests. Single-blind, placebo-controlled oral challenges were positive with TMP and negative with SMX in all patients. These results suggest that the three patients developed type I hypersensitivity reactions to TMP. In our patients skin prick tests with TMP were useful in TMP hypersensitivity diagnosis.

Recognising Antibacterial Hypersensitivity In Children

“…[3] However, there have been occasional reports of skin test positivity in patients with serious immediate hypersensitivity [37][38][39][40] macrolides, [41,42] rifampicin (rifampin), [43] rifamycin, [44] sulfamethoxazole [45] and trimethoprim. [46][47][48] Thus, it could be worthwhile to perform skin tests with non-β-lactam antibacterials even though, because of the rarity of these reactions, they are not standardised or validated.…”

“…Assays are currently available for benzylpenicillin (penicillin G), phenoxymethylpenicillin (penicillin V), ampicillin, amoxicillin and cefaclor. However, over the last 10 years experiments have detected positive titres of IgE specific for cephalosporins, [58][59][60][61] sulfonamides, [45,62,63] trimethoprim [46][47][48]64,65] and erythromycin [41] in individuals with histories of immediate reactions. These findings do not always confirm skin test results.…”

Anaphylaxis to trimethoprim: An under‐appreciated risk in acute medical care

“…In another study, cotrimoxazole use resulted in two anaphylactic cases and one generalized urticarial reaction. In all three, skin‐prick and rechallenge testing to trimethoprim were positive whilst negative to the sulphamethoxazole component 18 …”

Anaphylactic reactions associated with trimethoprim

“…In another report three case‐histories were described, two of patients with anaphylactic reactions, and one with generalized urticaria after use of cotrimoxazole, who had positive skin‐prick tests and rechallenge‐tests to trimethoprim, and negative skin prick and intradermal tests and rechallenge tests to sulphamethoxazole. No significant levels of specific IgE to trimethoprim could be detected [ 11]. One other report discussed a patient with an anaphylactic reaction to cotrimoxazole, who had a positive skin‐prick test and specific IgE with a positive RAST‐inhibition to trimethoprim, while skin‐prick and intradermal tests to sulphamethoxazole were negative and no IgE against sulphamethoxazole could be found [ 12].…”