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Cross-reactivity seen in patients with hypersensitivity to penicillin

Patients with a positive reaction to aminopenicillins may also have a reaction to aminocephalosporins such as cefuroxime, ceftriaxone, and aztreonam, according to recent research.

“Our study demonstrated a rate of cross-reactivity between penicillins and aminocephalosporins of around 20%, as well as the absence of cross-reactivity between penicillins and cefuroxime, ceftriaxone, and aztreonam in all subjects with a T-cell–mediated hypersensitivity to penicillins, almost exclusively aminopenicillins,” Antonino Romano, MD, from the Allergy Unit at the Complesso Integrato Columbus in Rome, and colleagues wrote in their study. “Therefore these subjects could be treated with cefuroxime, ceftriaxone, and aztreonam.”

Romano and colleagues prospectively evaluated 214 participants with 308 non-immediate reactions to a minimum of one penicillin reagent as measured through positive patch tests or a delayed-reading skin test response, according to the abstract. Participants underwent cross-reactivity testing for aztreonam, cephalexin, cefaclor, cefadroxil, cefuroxime and ceftriaxone, with participants displaying a negative reaction receiving challenges for alternative β-lactams.

They found all patients tolerated the challenges and had negative reactions to aztreonam, ceftriaxone and cefuroxime, according to the abstract. There were 40 of 214 participants (18.7%) who had a positive skin test to a minimum of 1 aminocephalosporin; of the patients with negative responses (174 participants), the researchers noted 1 participant had a positive reaction to cefaclor out of 170 participants who underwent challenges.

“Nevertheless, until further studies confirm our data, in patients with such hypersensitivity who need these alternative β-lactams, we recommend pretreatment skin tests,” Romano and colleagues wrote. “Considering that only one of our challenged patients had a cutaneous reaction and only at the full dose of cefaclor, graded challenges are not required when aztreonam and cephalosporins (eg, especially cefuroxime and ceftriaxone), which have side chains different from those of penicillins, are administered to patients with penicillin allergy who have negative pretreatment skin test responses to these alternative b-lactams.” – by Jeff Craven

Disclosure: The researchers report no relevant financial disclosures.