The role of skin tests with polyethylene glycol and polysorbate 80 in the vaccination campaign for COVID-19: results from an Italian multicenter survey.

Summary: Background. International guidelines suggested skin tests with Polyethylene-glycol (PEG) and polysorbate 80 (PS-80), to investigate a possible hypersensitivity to these excipients either to identify subjects at risk of developing allergic reactions to Covid-19 vaccines, or in patients with suspected IgE mediated hypersensitivity reactions (HR) to the Covid-19 vaccine. The main purpose of this study was to investigate the prevalence of PEG and PS sensitization in patients with a clinical history of HR to drugs containing PEG/PS and in patients with a suspected Covid-19 vaccine immediate HR. Methods. This was a multicenter retrospective study conducted by allergists belonging to 20 Italian medical centers. Skin testing was performed in 531 patients with either a clinical history of suspected hypersensitivity reaction (HR) to drugs containing PEG and/or PS-80 (group 1:362 patient) or a suspected HR to Covid-19 vaccines (group 2: 169 patient), as suggested by the AAIITO/SIAAIC guidelines for the "management of patients at risk of allergic reactions to Covid-19 vaccines" [1]. Results. 10/362 (0.02%) had positive skin test to one or both excipients in group 1, 12/169 (7.1%) in group 2 (p less than 0.01). In group 2 HRs to Covid-19 vaccines were immediate in 10/12 of cases and anaphylaxis occurred in 4/12 of patients. Conclusions. The positivity of skin test with PEG and or PS before vaccination is extremely rare and mostly replaceable by an accurate clinical history. Sensitization to PEG and PS has to be investigated in patients with a previous immediate HR to a Covid-19 vaccine, in particular in patients with anaphylaxis.

Sensitization to Gibberellin-Regulated Protein (Peamaclein) Among Italian Cypress Pollen–Sensitized Patients

Background: Peach gibberellin-regulated protein (peamaclein) has recently emerged as a relevant food allergen in cypress pollen–hypersensitive patients.Objective: We investigated monosensitization to peamaclein among Italian cypress pollen–allergic patients.Patients: A total of 835 cypress pollen–hypersensitive patients from 28 Italian allergy centers underwent a thorough work-up to determine food-allergic reactions and performed skin prick testing with a commercial peach extract containing peamaclein. IgE to rPru p 3 was measured in peach reactors, and those with negative results were enrolled as potentially monosensitized to peamaclein. IgE reactivity to rPru p 7 was evaluated using immunoblot and an experimental ImmunoCAP with rPru p 7.Results: Skin prick tests were positive to peach in 163 patients (19.5%); however, 127 (77.9%) were excluded because they reacted to Pru p 3. Twenty-four patients (14.7%) corresponding to 2.8% of the entire study population) were considered potentially monosensitized to peamaclein. No geographic preference was observed. Seventeen of the 24 patients (70.8%) had a history of food allergy, mainly to peach (n=15). Additional offending foods included other Rosaceae, citrus fruits, fig, melon, tree nuts, and kiwi. On peach immunoblot, only 3 of 18 putative peamaclein–allergic patients reacted to a band at about 7 kDa; an additional 4 patients reacted at about 50-60 kDa. Ten of 18 patients (56%) had a positive result for Pru p 7 on ImmunoCAP.Conclusion: Allergy and sensitization to peamaclein seem rare in Italy. Most patients react to peach, although other Rosaceae fruits and several citrus fruits may also be offending foods. Peach and cypress pollen probably also share cross-reacting allergens other than peamaclein (AU)

Antecedentes: La proteína del melocotón regulada por giberelina (peamacleina) ha sido descrita recientemente con alérgeno alimentarioen los pacientes con alergia al polen de ciprés.Objetivo: Determinar la presencia de monosensibilización a peamacleina en los pacientes italianos con alergia al polen de ciprés.Pacientes: Se estudiaron 835 pacientes italianos con alergia al polen de ciprés, provenientes de 28 centros hospitalarios. En todos ellosse realizó historia clínica dirigida a detectar alergia alimentaria así como prick test con extractos comerciales de melocotón que conteníanpeamacleína. En los pacientes sensibilizados a melocotón se determinó IgE específica a Pru p 3 y aquellos con resultado negativo seclasificaron como potencialmente monosensibilizados a peamacleina. Se realizó determinación de IgE específica a Pru p 7 medianteimmunoblot e ImmunoCAP con Pru p 7.Resultados: El prick test con melocotón fue positivo en 163 pacientes (19,5%), pero 127 de estos pacientes fueron excluidos por estarsensibilizados a Pru p 3. 24 pacientes (14,7%), que correspondían al 2,8% de la población global, fueron considerados como potencialmentemonosensibilizados a peamacleína. La distribución de estos pacientes no seguía ningún patrón geográfico. 17/24 (70,8%) tenían historiade alergia alimentaria, en la mayoría de los casos a melocotón (n=15). Los pacientes también referían síntomas con otros alimentoscomo otras frutas rosáceas, cítricos, higo, melón, frutos secos y kiwi. Solo 3/18 pacientes presentaban en el immunoblot una banda dealrededor de 7 kDa; otros 4 pacientes reconocían una banda de 50-60 kDa. 10/18 presentaron positividad en el ImmunoCAP a Pru p 7.Conclusión: En Italia, la alergia o sensibilización a peamacleina es baja. La mayor parte de los pacientes reaccionan con el melocotón,aunque otras frutas rosáceas y cítricos también desencadenan síntomas

Evaluation of two commercial peach extracts for skin prick testing in the diagnosis of hypersensitivity to lipid transfer protein. A multicenter study.

Summary: The clinical usefulness of two commercial peach extracts for SPT (by Lofarma SpA and ALK-Abellò, respectively) was compared in a multicenter study carried out in Italy. Peach allergic patients were tested with the two extracts in parallel and underwent the detection of IgE specific for all three peach allergens currently available (Pru p1, Pru p3, and Pru p4, respectively). The two extracts were almost identical in terms of sensitivity and specificity, being able to detect virtually all patients sensitized to stable peach allergens (lipid transfer protein (LTP) and, presumably, peamaclein) but scoring negative in patients exclusively sensitive to labile allergens (either PR-10 and/or profilin). Thus, the two extracts represent an excellent tool to carry out a preliminary component-resolved diagnosis of peach allergy at the first patient visit.

Sensitization to Gibberellin-Regulated Protein (Peamaclein) Among Italian Cypress Pollen-Sensitized Patients.

BACKGROUND AND OBJECTIVES: Peach gibberellin-regulated protein (peamaclein) has recently emerged as a relevant food allergen in cypress pollen-hypersensitive patients. Objective: We investigated monosensitization to peamaclein among Italian cypress pollen-allergic patients. MATERIAL AND METHODS: A total of 835 cypress pollen-hypersensitive patients from 28 Italian allergy centers underwent a thorough work-up to determine food-allergic reactions and performed skin prick testing with a commercial peach extract containing peamaclein. IgE to rPru p 3 was measured in peach reactors, and those with negative results were enrolled as potentially monosensitized to peamaclein. IgE reactivity to rPru p 7 was evaluated using immunoblot and an experimental ImmunoCAP with rPru p 7. RESULTS: Skin prick tests were positive to peach in 163 patients (19.5%); however, 127 (77.9%) were excluded because they reacted to Pru p 3. Twenty-four patients (14.7%) corresponding to 2.8% of the entire study population) were considered potentially monosensitized to peamaclein. No geographic preference was observed. Seventeen of the 24 patients (70.8%) had a history of food allergy, mainly to peach (n=15). Additional offending foods included other Rosaceae, citrus fruits, fig, melon, tree nuts, and kiwi. On peach immunoblot, only 3 of 18 putative peamaclein-allergic patients reacted to a band at about 7 kDa; an additional 4 patients reacted at about 50-60 kDa. Ten of 18 patients (56%) had a positive result for Pru p 7 on ImmunoCAP. CONCLUSION: Allergy and sensitization to peamaclein seem rare in Italy. Most patients react to peach, although other Rosaceae fruits and several citrus fruits may also be offending foods. Peach and cypress pollen probably also share cross-reacting allergens other than peamaclein.

LTP allergy/sensitization in a pediatric population

Plant lipid transfer proteins (LTPs) are widespread plant food allergens, highly resistant to food processing and to the gastrointestinal environment, which have been described as the most common food allergens in the Mediterranean area. LTP allergy is widely described in adults, but it represents an emerging allergen also in the pediatric population. Little is known about the real prevalence and the clinical features of this allergy in children and it still often remains underdiagnosed in these patients. An early identification and a deeper knowledge of this allergy in childhood can avoid severe systemic reactions and improve the child's quality of life. Pediatricians should always consider the possibility of LTP involvement in cases of plant-derived food allergy

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Adverse reaction to Ficus Carica: reported case of a possible cross-reactivity with Der p1.

BACKGROUND: Ficus carica is an edible fruit, belonging to the Moraceae family, rarely described as cause of food allergy. We describe the first case of fig allergy that occurred as a cross-reactivity between fig and Derp 1. CASE PRESENTATION: We present a case of a 10-years-old-girl, with a history of no-seasonal mild intermittent rhinitis, who experienced an immediate reaction after ingestion of a fresh fig. Skin prick tests (SPT) with commercial extracts of food, airborne allergens, latex and panallergens (profilin, PR-10 and lipid transfer protein) were performed. SPT revealed a sensitization only for dermatophagoides farina and dermatophagoides pteronyssinus which was then confirmed with by specific IgE assay (UniCAP, Phadia, Uppsala, Sweden). We also carried out a positive SPT with a commercial fig allergen (Lofarma, Milan, Italy) and prick-by-prick (PBP) both with skin and pulp of green raw and cooked fig. Fig specific serum IgE levels were 1.08 U/ml and specific IgE for rDer p1 was 16.20 U/ml (total serum IgE = 377 U/ml). In contrast specific IgE levels for latex, LTP, profilin, PR-10 and pollen allergens were negative. CONCLUSION: The ficin, the major fig allergen, belongs to cysteine protease family like Der p 1. The symptoms presented by our patient could be related to a cross reactivity between these two proteins which present a structural homology.

LTP allergy/sensitization in a pediatric population.

Plant lipid transfer proteins (LTPs) are widespread plant food allergens, highly resistant to food processing and to the gastrointestinal environment, which have been described as the most common food allergens in the Mediterranean area. LTP allergy is widely described in adults, but it represents an emerging allergen also in the pediatric population. Little is known about the real prevalence and the clinical features of this allergy in children and it still often remains underdiagnosed in these patients. An early identification and a deeper knowledge of this allergy in childhood can avoid severe systemic reactions and improve the child's quality of life. Pediatricians should always consider the possibility of LTP involvement in cases of plant-derived food allergy.

House dust mite allergy and shrimp allergy: a complex interaction.

Summary: Background and Objective. Sensitization and allergy to shrimp among Italian house dust mite allergic patients are not well defined and were investigated in a large multicenter study. Methods. Shrimp sensitization and allergy were assessed in 526 house dust mite (HDM)-allergic patients submitted to the detection of IgE to Der p 10 and 100 atopic control not sensitized to HDM. Results. Shrimp allergy occurred in 9% of patients (vs 0% of 100 atopic controls not sensitized to HDM; p minor 0.001). Shrimp-allergic patients were less frequently hypersensitive to airborne allergens other than HDM than crustacean-tolerant subjects (35% vs 58.8%; p minor 0.005). Only 51% of tropomyosin-sensitized patients had shrimp allergy, and these showed significantly higher Der p 10 IgE levels than shrimp-tolerant ones (mean 22.2 KU/l vs 6.2 KU/l; p minor 0.05). Altogether 53% of shrimp-allergic patients did not react against tropomyosin. Conclusions. Shrimp allergy seems to occur uniquely in association with hypersensitivity to HDM allergens and tropomyosin is the main shrimp allergen but not a major one, at least in Italy. Along with tropomyosin-specific IgE levels, monosensitization to HDM seems to represent a risk factor for the development of shrimp allergy among HDM allergic patients.

Cross-reactivity and Tolerability of Ertapenem in Patients With IgE-Mediated Hypersensitivity to ß-Lactams.

BACKGROUND AND OBJECTIVE: Administration of carbapenems to ß-lactam-allergic patients has always been considered potentially harmful because of a 47.4% rate of cross-reactivity to imipenem reported in a single study. Nevertheless, recent studies have shown that the rate of cross-reactivity of imipenem and meropenem with penicillins is lower than 1%. The aim of this study was to evaluate the possibility of using ertapenem in patients with an established IgE-mediated ß-lactam allergy. PATIENTS AND METHODS: We studied all participants who came to our allergy unit and had a clinical history of immediate hypersensitivity reactions to ß-lactams. The inclusion criteria were a positive skin test result to at least 1 ß-lactam molecule and/or positive specific IgE (when available). All participants underwent immediate-type skin tests with several ß-lactam molecules including ertapenem. Challenges with intravenous ertapenem were performed on 2 different days in patients with negative skin test results. RESULTS: We examined 49 patients with a clinical history of immediate reactions to ß-lactams. All the patients had positive skin tests and/or positive specific IgE to at least 1 ß-lactam reagent and negative carbapenem skin tests. Thirty-six patients agreed to undergo the challenges and 35 tolerated the full dose of ertapenem. CONCLUSIONS: The practice of avoiding carbapenems in patients with ß-lactam allergy should be abandoned considering the very low rate of cross-reactivity. ß-Lactam-allergic patients who need ertapenem therapy should undergo skin tests and, if negative, a graded challenge to assess tolerability.

Cross-reactivity and tolerability of Ertapenem in patients with IgE-mediated hypersensitivy to Beta-lactams

Background and Objective: Administration of carbapenems to β-lactam-allergic patients has always been considered potentially harmful because of a 47.4% rate of cross-reactivity to imipenem reported in a single study. Nevertheless, recent studies have shown that the rate of cross-reactivity of imipenem and meropenem with penicillins is lower than 1%. The aim of this study was to evaluate the possibility of using ertapenem in patients with an established IgE-mediated β-lactam allergy. Patients and Methods: We studied all participants who came to our allergy unit and had a clinical history of immediate hypersensitivity reactions to β-lactams. The inclusion criteria were a positive skin test result to at least 1 β-lactam molecule and/or positive specific IgE (when available). All participants underwent immediate-type skin tests with several β-lactam molecules including ertapenem. Challenges with intravenous ertapenem were performed on 2 different days in patients with negative skin test results. Results: We examined 49 patients with a clinical history of immediate reactions to β-lactams. All the patients had positive skin tests and/or positive specific IgE to at least 1 β-lactam reagent and negative carbapenem skin tests. Thirty-six patients agreed to undergo the challenges and 35 tolerated the full dose of ertapenem. Conclusions: The practice of avoiding carbapenems in patients with β-lactam allergy should be abandoned considering the very low rate of cross-reactivity. β-Lactam-allergic patients who need ertapenem therapy should undergo skin tests and, if negative, a graded challenge to assess tolerability (AU)

Introducción y Objetivo: Siempre se ha considerado peligrosa la administración de carbapenems a pacientes alérgicos a betalactámicos por la presencia de reactividad cruzada en el 47,4% de los casos descrita en un estudio previo. Sin embargo, estudios recientes han mostrado que la reactividad cruzada de imipenem y meropenem con penicilinas es inferior al 1%. El objetivo de este estudio es valorar el uso de ertapenem en pacientes diagnosticado de alergia IgE mediada a betalactámicos. Pacientes y Métodos: Se incluyeron todos los pacientes que acudieron a nuestra unidad de Alergia con historia clínica de alergia inmediata a betalactámicos. Los criterios de inclusión fueron prueba cutánea positiva con al menos un betalactámico y/o IgE específica positiva (cuando estuviese disponible). Se realizaron pruebas cutáneas con betalactámicos, incluyendo ertapenem, con lectura inmediata en todos los pacientes. Se realizaron pruebas de provocación endovenosas con ertapenem en los pacientes con pruebas cutáneas negativas frente al mismo en dos días diferentes. Resultados: Se incluyeron 49 pacientes con historia clínica de alergia inmediata a betalactámicos. Todos los pacientes tenían pruebas cutáneas positivas y/o IgE específica positiva al menos a uno de los betalactámicos así como prueba cutánea negativa con carbapenémicos. Treinta y seis pacientes aceptaron la realización de pruebas de provocación con ertapenem que fueron tolerados por treinta y cinco de dichos pacientes. Conclusión: El hecho de recomendar evitar carbapenems en pacientes con alergia a betalactámicos debería ser abandonado, dada la baja reactividad cruzada que presentan. En los pacientes con alergia a betalactámicos que necesiten ertapenem se deberían realizar pruebas cutáneas con el fármaco y en caso de ser negativas, realizar un test de exposición progresiva para confirmar su tolerancia (AU)

Cross-reactivity and tolerability of cephalosporins in patients with cell-mediated allergy to penicillins.

BACKGROUND AND OBJECTIVE: 13-Lactams are the most commonly used antibiotics but they can cause hypersensitivity reactions. We sought to estimate cross-reactivity and tolerability of cephalosporins in patients with cell-mediated allergy to penicillins. METHODS: We studied 97 patients with a clinical history of nonimmediate reactions to a penicillin and a positive patch test result to at least 1 of the penicillins tested. All patients also underwent patch testing with several cephalosporins. Patients with a negative patch test to a cephalosporin underwent test dosing in order to assess tolerability. RESULTS: We recorded 129 reactions. The most commonly involved drugs were aminopenicillins, and the most widely reported symptoms were delayed urticaria and maculopapular exanthema. Seventeen patients had positive patch test results for cephalosporins, mostly for cephalexin (n=10), cefaclor (n=9), and cefuroxime axetil (n=5). All the patients-except 4 who experienced an exanthema after the challenge test with cephalexin-tolerated a therapeutic dose of the cephalosporin tested without any adverse effects. CONCLUSIONS: Our data show that cross-reactivity between penicillins and cephalosporins may be as high as 10.9% for first-generation cephalosporins and 1.1% for third-generation cephalosporins, possibly due to the involvement of similar side chains. Patch tests are a useful diagnostic tool to assess cross-reactivity, but a graded challenge is mandatory because a negative patch test does not always mean tolerability.

Cross-reactivity and tolerability of cephalosporins in patients with cell-mediated allergy to penicillins

Background and objective: b-Lactams are the most commonly used antibiotics but they can cause hypersensitivity reactions. We sought to estimate cross-reactivity and tolerability of cephalosporins in patients with cell-mediated allergy to penicillins. Methods: We studied 97 patients with a clinical history of nonimmediate reactions to a penicillin and a positive patch test result to at least 1 of the penicillins tested. All patients also underwent patch testing with several cephalosporins. Patients with a negative patch test to a cephalosporin underwent test dosing in order to assess tolerability. Results: We recorded 129 reactions. The most commonly involved drugs were aminopenicillins, and the most widely reported symptoms were delayed urticaria and maculopapular exanthema. Seventeen patients had positive patch test results for cephalosporins, mostly for cephalexin (n=10), cefaclor (n=9), and cefuroxime axetil (n = 5). All the patients-except 4 who experienced an exanthema after the challenge test with cephalexin—tolerated a therapeutic dose of the cephalosporin tested without any adverse effects. Conclusions: Our data show that cross-reactivity between penicillins and cephalosporins may be as high as 10.9% for first-generation cephalosporins and 1.1% for third-generation cephalosporins, possibly due to the involvement of similar side chains. Patch tests are a useful diagnostic tool to assess cross-reactivity, but a graded challenge is mandatory because a negative patch test does not always mean tolerability (AU)

Introducción y objetivo: Los antibióticos betalactámicos son los más comúnmente utilizados y pueden ser responsables del desarrollo de reacciones de hipersensibilidad. Este estudio pretende estimar la reactividad cruzada y la tolerancia a las cefalosporinas en pacientes con alergia mediada por células a penicilinas. Métodos: Estudiamos 97 pacientes con historia clínica de reacciones no inmediatas a penicilina y que habían tenido una prueba de parche positiva al menos frente a una de las penicilinas testadas. También se realizó parche frente a alguna cefalosporina en todos ellos. Los pacientes con negatividad en esta prueba se sometieron a la prueba de tolerancia. Resultados: Se recopilaron 129 reacciones, la mayoría de los medicamentos implicados fueron aminopenicilinas, siendo los síntomas más frecuentes la urticaria de aparición tardía y el exantema máculo-papular. Diecisiete pacientes arrojaron resultados positivos en la prueba del parche a cefalosporinas, cefalexina (10 casos), ceflacor (9) y acetil-cefuroxima (5). Todos los pacientes excepto 4 (los cuales tuvieron un eccema tras la provocación con cefalexina), toleraron la dosis terapéutica de la cefalosporina probada sin ningún efecto dañino. Conclusiones: Según nuestros resultados, la reactividad cruzada entre penicilinas y cefalosporinas es de 10,9% para las cefalosporinas de primera generación y de 1,1% para las de tercera generación. Esto puede ser debido a las cadenas similares implicadas. La prueba del parche es una herramienta diagnóstica útil para evaluar la reactividad cruzada, pero necesita una provocación gradual, dado que una prueba del parche negativa no implica tolerancia (AU)

Gene expression profiling of patients with latex and/or vegetable food allergy.

BACKGROUND: The prevalence of individuals allergic to latex, exhibiting cross-hypersensitivity with plant-derived food has been frequently reported as the so-called latex-fruit syndrome. Nonetheless, molecular mechanisms underlying allergy to latex and/or fruit are poorly understood. AIM: The aims of this study were to identify candidate genes that may be associated with the pathogenesis of allergy to latex and/or vegetable food, and to assess if similar molecular pathways are involved in both types of hypersensitivity. MATERIALS AND METHODS: DNA microarray analysis was performed to screen the molecular profiles of peripheral blood mononuclear cells isolated from patients with allergy to latex, to fruit, or with latex-fruit syndrome, and from control healthy subjects. RESULTS: Molecular profiling identified an overlapping dataset of genes commonly regulated in all the atopic patients enrolled in this study, suggesting that similar molecular mechanisms are involved in the pathogenesis of allergy to the fruit and/or latex. Several regulators of the innate and acquired immunity reported to polarize the immunological response towards a Th2-mediated immune response were overexpressed in the patients. Evidences suggested that the expression of T-regulatory cells might be defective in allergic patients, as a consequence of a dysregulation of some inflammatory cytokines. Finally, several transcription factors that may be responsible for the Th1/Th2 imbalance were modulated in allergic patients. CONCLUSIONS: This study identified relevant genes that may help to elucidate the molecular mechanisms underlying allergic disease. Knowledges of critical targets, along with transcription factors regulating gene activity may facilitate the development of new therapeutic options.

The clinical meaning of positive latex sIgE in patients with food/pollen adverse reactions.

Natural rubber latex allergy (NRL-A) is an international problem of public health. About 50-60% of NRL-A patients may present adverse reactions after ingestion of cross-reacting vegetable foods. This condition, called "Latex-fruit Syndrome", is a matter of research. The aim of our study is to distinguish between clinical/subclinical latex-fruit syndrome and cross-sensitization to latex and food/pollen allergens on the basis of latex recombinant allergens. We studied 51 patients with food hypersensitivity and serological evidence of NRL sensitization. The subjects underwent an accurate allergological evaluation (skin prick test with latex, food and pollen extracts, specific IgE to latex and recombinant allergens, challenge provocation tests). The patients were divided in two groups: group A) 34 patients with clinical and serological latex and fruit/vegetable allergies; group B) 17 patients allergic to fruits/vegetables and/or pollens, with serological, but not clinical NRL-A. All the latex challenge tests resulted positive in group A patients and only two patients of group B presented positive cutaneous challenge tests. Moreover, specific IgE-antibodies were detected to rHev b 5, to rHev b 6.01, to rHev b 6.02 and to rHev b 8 (and other profilins) of group A patients, while in group B we observed a monosensitization to Hev b8, probably linked to a cross-sensitization to pollens and foods. At the present state of knowledge, we need a multi-parametric approach based on a combination of clinical history, diagnostic tests (CRD) and latex challenge tests to make diagnosis of latex-fruit syndrome.

Profilin desensitization in two patients with plant-derived food allergy.

Profilins are "panallergens", responsible for many cross-reactivities between inhalant, latex and plant-derived food allergens. We evaluated the effectiveness and the safety of sublingual desensitization treatment (SLIT) in two patients with allergic respiratory and food diseases. Skin prick tests, IgE and IgG4 assays to pollens, some plant-derived foods, profilin, non-lipid specific transfer protein and PR 10 proteins were performed. The patients also underwent double-blind placebo-controlled challenge (DBPCFC) with the culprit foods and profilin and then a SLIT with it. Both the patients had positive SPT, specific IgE and DBPCFCs with profilin and some vegetables referred in anamnesis. They therefore underwent SLIT with profilin extract. At the end of treatment, the patients had negative DBPCFCs with culprit foods and a decrease of specific IgE levels for profilin and vegetable foods. Profilin desensitization allowed our patients to manage their diet without restriction, eating several foods previously not tolerated.

Tolerability of aztreonam in patients with cell-mediated allergy to ß-lactams.

BACKGROUND: Cross-reactivity between aztreonam and ß-lactams is poor, but tolerability of aztreonam has been assessed in a few groups of patients suffering from IgE-mediated allergy to ß-lactams. The aim of this study was to assess the cross-reactivity of aztreonam with other ß-lactams and its tolerability in patients with cell-mediated allergy to these drugs. METHODS: We studied 78 patients with cell-mediated allergy to ß-lactams who underwent skin prick, immediate and delayed-reading intradermal tests as well as patch tests with penicilloyl-polylysine, minor determinant mixture, semi-synthetic penicillins, cephalosporins, aztreonam and imipenem. Patients with negative allergy testing with aztreonam underwent an intramuscular test dosing and were observed for 3 h. RESULTS: Our patients experienced 94 non-immediate reactions; delayed-onset urticaria (34 cases), maculopapular exanthema (13 cases), urticaria/angioedema (15 cases) and itching erythema (13 cases) were the most reported symptoms. Amoxicillin (35 cases), ampicillin (28 cases) and bacampicillin (18 cases) were the most involved drugs. All patients had a positive patch test and/or a positive delayed-reading intradermal test to at least 1 ß-lactam antibiotic and none had a positive patch or delayed-reading intradermal test to aztreonam. Then, 65 patients underwent intramuscular test dosing with aztroenam, and none of them had a clinical reaction. CONCLUSIONS: Our data confirm the lack of cross-reactivity between ß-lactams and aztreonam in patients with cell-mediated allergy to these drugs. Delayed-reading intradermal tests and patch tests with aztreonam represent a simple and rapid diagnostic tool to establish tolerability in ß-lactam-allergic patients.