IMMEDIATE ALLERGIC REACTIONS TO AMOXICILLIN

A large group of patients with suspected allergic reactions to beta-la ctam antibiotics was evaluated. A detailed clinical history, together with skin tests, RAST (radioallergosorbent test), and controlled chall enge tests, was used to establish whether patients allergic to beta-la ctam antibiotics had selective immediate allergic responses to amoxici llin (AX) or were cross-reacting with other penicillin derivatives. Sk in tests were performed with benzylpenicilloyl-poly-L-lysine (BPO-PLL) , benzylpenicilloate, benzylpenicillin (PG), ampicillin (AMP), and AX. RAST for BPO-PLL and AX-PLL was done. When both skin test and RAST fo r BPO were negative, single-blind, placebo-controlled challenge tests were done to ensure tolerance of PG or sensitivity to AX. A total of 1 77 patients were diagnosed as allergic to beta-lactam antibiotics. We selected the 54 (30.5%) cases of immediate AX allergy with good tolera nce of PG. Anaphylaxis was seen in 37 patients (69%), the other 17 (31 %) having urticaria and/or angioedema. All the patients were skin test negative to BPO; 49 of 51 (96%) were also negative to MDM, and 44 of 46 (96%) to PG. Skin tests with AX were positive in 34 (63%) patients. RAST was positive for AX in 22 patients (41%) and to BPO in just 5 (9 0%). None of the sera with negative RAST for AX were positive to BPO. Challenge tests with AX were performed in 23 subjects (43%) to establi sh the diagnosis of immediate allergic reaction to AX, and in 15 cases (28%) both skin test and RAST for AX were negative. PG was well toler ated by all 54 patients. We describe the largest group of AX-allergic patients who have tolerated PG reported so far. Diagnosis of these pat ients can be achieved only if specific AX-related reagents are employe d. Further studies are necessary to determine the exact extent of this problem and to improve the efficacy of diagnostic methods.