{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T20:13:14Z","timestamp":1789589594735,"version":"build-2803163510"},"reference-count":16,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2025,3,16]],"date-time":"2025-03-16T00:00:00Z","timestamp":1742083200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Contact Dermatitis"],"published-print":{"date-parts":[[2025,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Introduction<\/jats:title><jats:p>Patients with non\u2010immediate hypersensitivity to beta\u2010lactam antibiotics (\u03b2L) often avoid all \u03b2L, with limitations for future therapy.<\/jats:p><\/jats:sec><jats:sec><jats:title>Objectives<\/jats:title><jats:p>Assess cross\u2010reactivity between \u03b2L in non\u2010immediate cutaneous adverse drug reactions (ni\u2010CADRs).<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Retrospective analysis (2000\u20132022) of patients with suspected ni\u2010CADR with \u03b2L as a possible culprit who underwent patch testing (PT) with an extended antibiotic series (10% pet., Chemotechnique Diagnostics or prepared in\u2010house) according to European Society of Contact Dermatitis (ESCD) recommendations. Fisher exact test was used with a significance of 0.05 corrected for multiple testing; positive associations were quantified with odds ratio (OR) with 95% confidence interval (CI).<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Four hundred and fourteen patients (270 female\/144 male; age 52\u2009\u00b1\u200919\u2009years) were included, mostly with maculopapular exanthema (367; 89%), drug reaction with eosinophilia and systemic symptoms (DRESS) (22; 5%) and acute generalised exanthematous pustulosis (AGEP) (12; 3%). Eighty\u2010six patients (21%) had positive results to at least one drug. Fifty\u2010eight patients (14%) had 110 positive results to \u03b2L, mostly amoxicillin (33). Co\u2010reactivity within penicillins was almost universal, including piperacillin with other penicillins (<jats:italic>p<\/jats:italic>\u2009=\u20090.007; OR 25; CI 3\u201356). There was co\u2010reactivity to aminopenicillins and aminocephalosporins (<jats:italic>p<\/jats:italic>\u2009=\u20090.006; OR 33; CI 4\u201374) and within the cephalosporin subclass, including between aminocephalosporins and non\u2010aminocephalosporins. Within carbapenems, 1 patient reacted to meropenem and ertapenem, with no extension to imipenem, as confirmed with a provocation test. Two patients reacted both to ceftriaxone and meropenem (<jats:italic>p<\/jats:italic>\u2009=\u20090.013; OR: 68; CI:15\u2013612).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>PT is useful to confirm a probable culprit in ni\u2010CADR to \u03b2L. Co\u2010reactivity, interpreted mostly as cross\u2010reactivity, occurred within cephalosporin and, particularly, with penicillin subclasses, including between piperacillin\u2010tazobactam and remaining penicillins, which has seldom been described. There was no association between penicillins and cephalosporins as a whole, except between aminopenicillins and aminocephalosporins, attributable to a similar lateral chain amino group. We found an unexpected association between meropenem and ceftriaxone, probably a concomitant sensitization.<\/jats:p><\/jats:sec>","DOI":"10.1111\/cod.14767","type":"journal-article","created":{"date-parts":[[2025,3,16]],"date-time":"2025-03-16T23:09:06Z","timestamp":1742166546000},"page":"298-304","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Decoding Beta\u2010Lactam Cross\u2010Reactivity \u2013 Longitudinal Patch Testing From 2000 to 2022"],"prefix":"10.1111","volume":"93","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2642-1773","authenticated-orcid":false,"given":"Jo\u00e3o Nuno Barbosa","family":"Soares","sequence":"first","affiliation":[{"name":"Dermatology University Hospital, Coimbra Local Health Unit  Coimbra Portugal"},{"name":"Faculty of Medicine University of Coimbra  Coimbra Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andr\u00e9 Apar\u00edcio","family":"Martins","sequence":"additional","affiliation":[{"name":"Dermatology University Hospital, Coimbra Local Health Unit  Coimbra Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ana Carolina","family":"Figueiredo","sequence":"additional","affiliation":[{"name":"Dermatology University Hospital, Coimbra Local Health Unit  Coimbra Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andr\u00e9 Castro","family":"Pinho","sequence":"additional","affiliation":[{"name":"Dermatology University Hospital, Coimbra Local Health Unit  Coimbra Portugal"},{"name":"Faculty of Medicine University of Coimbra  Coimbra Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Francisco","family":"Caramelo","sequence":"additional","affiliation":[{"name":"Faculty of Medicine University of Coimbra  Coimbra Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6842-1360","authenticated-orcid":false,"given":"Margarida","family":"Gon\u00e7alo","sequence":"additional","affiliation":[{"name":"Dermatology University Hospital, Coimbra Local Health Unit  Coimbra Portugal"},{"name":"Faculty of Medicine University of Coimbra  Coimbra 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