Penicillins hypersensitivity reactions, cross-reactivity with

As with the penicillins, hypersensitivity reactions are the most common systemic adverse events caused by cephalosporins. Maculopapular rash, urticaria, fever, bron-chospasm,and anaphylaxis have been associated with the use of cephalosporins.Because the molecular structure of the penicillins and the first-generation cephalosporins are similar, there is a risk in patients who are aUergic to penicillin to manifest aUergic cross-reactions when prescribed any of this gronp of cephalosporins. In contrast, the risk of cross-reactivity between the penicUUns and the second-, third-, and fonrth-generation cephalosporins has been overestimated, and patients with a previons aUergic... 

Hypersensitity reaction in patients with hypersensitivity reactions to penicillins, the incidence of cross-reactivity to carbapenems is 50%. 

The cephalosporins generally cause few side effects (80,132,219—221). Thrombophlebitis occurs as a result of intravenous administration of all cephalosporins. Hypersensitivity reactions related to the cephalosporins are the most common side effects observed, but these are less common than found with the penicillins. Clinically only about 5—10% of patients with allergic reactions to the penicillins manifest the same reactions to the cephalosporins, and data would contradict any tme cross-reactivity to cephalosporins in patients who have previously reacted to penicillin (80,132,219). 

Allergy Cephalosporins cause a range of allergic reactions from skin rashes to anaphylactic shock. These reactions occur less frequently with cephalosporins than with penicillins. Complete cross-hypersensitivity between different cephalosporins should be assumed. Cross-reactivity between penicillins and cephalosporins is incomplete (5-10%), so penicillin-allergic patients are sometimes treated successfully with a cephalosporin. However, patients with a history of anaphylaxis to penicillins should not be treated with a cephalosporin. 

Each of the dmgs listed has activity against some gram-negative bacilli. All penicillins should be avoided in patients with a history of allergic reactions to any individual penicillin drug. Cephalosporins should also be avoided in patients who have had anaphylaxis or other severe hypersensitivity reactions following use of a penicillin. There is no cross-reactivity between the penicillins and aztreonam. The answer is (B). 

The question of tolerability of penicillins, monobactams, and carbapenems in patients with IgE hypersensitivity to cephalosporins was recently assessed in 98 subjects by serum IgE antibody assays, challenge tests, and skin testing with penicillin reagents, aztreonam, imipenem-cilastatin, and meropenem. Approximately 25 % of cephalosporin-allergic subjects were positive to penicillins, while 3.1,2, and 1 % showed positive results to aztreonam, imipenem, and meropenem, respectively. A reaction to a cephalosporin with a similar or identical side chain to penicillin was a sigifificant predictor of cross-reactivity. For skin testing, the following concentrations were used ampicillin and amoxicillin 1 and 20 mg/ml cephalosporins 2 mg/ml aztreonam 2 mg/ml imipenem-cilastatin 0.5 mg/ml and meropenem 1 mg/ml. 

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