Frequency and pattern of common primary headache among depressed patients at tertiary care centre, Karachi.

BACKGROUND

Bata-lactam antibiotics are the most commonly used antibiotics which usually cause serious IgE-mediated allergic reactions. Of all bata-lactam antibiotics, penicillins have so far been the best-studied, but the studies of cephalosporins and their cross-reactivity with penicillins are rare. We sought to evaluate the IgE response in vitro and estimate cross-reactivity between penicillins and cephalosporins in patients allergic to penicillins.

METHODS

We studied 87 control subjects and 420 subjects allergic to penicillins. Radioallergosorbent test (RAST) was performed to detect eight types of specific-penicillin IgE and eleven types of specific-cephalosporin IgE. The cross-reactivity and different molecules recognition by IgE were studied with a radioallergosorbent inhibition test.

RESULTS

Of 420 patients allergic to penicillins, 95 patients (22.62%) showed specific-cephalosporin IgE positive, 73 patients (17.38%) showed IgEs positive to both penicillins and cephalosporins. In specific-penicillin IgE positive group, the positive rate of specific-cephalosporin IgE was significantly higher than in specific-penicillin IgE negative group (27.14% vs. 14.57%, p < 0.01). In urticaria group, the positive rate of specific-cephalosporin IgE was significantly higher than in other symptoms group (30.65% vs. 8.11%, p < 0.05). The analysis of drugs which have the same or similar side-chains showed that benzylpenicillanyl-IgE (BPA-IgE), ampicillanyl-IgE (APA-IgE), amoxicillanyl-IgE (AXA-IgE) were respectively related to cephalothanyl-IgE (CLA-IgE), cephalexanyl-IgE (CEXA-IgE), cephalexanyl-IgE (CEXA-IgE)in sera of penicillin-allergic patients we studied, and compared with patients who had negative amoxicillin-IgE, the positive rates of specific-ampicillin IgE and specific-cephalexin IgE were significantly higher in patients who had positive amoxicillin-IgE (14.43% vs. 3.72%, 14.00% vs. 2.96%, p < 0.01). Radioallergosorbent test and radioallergosorbent inhibition test confirmed that both nuclear structure and R1 side-chain contribute to IgE recognition.

CONCLUSIONS

There exists cross-reactivity between cephalosporins and penicillins; patients allergic to several penicillins are more likely to develop allergic reaction to cephalosporins; due to sensitization to the similar structural characteristics (nuclear and R1 side-chain), penicillin-allergic patients may develop cross-allergic reactions with not only first-generation but also third-generation cephalosporins.