Update on the evaluation of hypersensitivity reactions to betalactams

Diagnosis and management of immediate hypersensitivity reactions to cephalosporins

Cephalosporins can cause a range of hypersensitivity reactions, including IgE-mediated, immediate reactions. Cephalosporin allergy has been reported with use of a specific cephalosporin, as a cross-reaction between different cephalosporins or as a cross-reaction to other β-lactam antibiotics. Unlike penicillins, the exact allergenic determinants of cephalosporins are less well understood and thus, standardized diagnostic skin testing is not available. Nevertheless, skin testing with diluted solutions of cephalosporins can be valuable in confirming IgE-mediated hypersensitivity reactions. In vitro tests are in development using recent technological advances and can be used as complementary tests. However, they are not commonly used because of their reduced sensitivity and limited availability. In selected cases of inconclusive results in both skin tests and IgE assays, a graded challenge or induction of drug tolerance with the implicated cephalosporin should be performed.

Immunologic evaluation of patients with cefotetan-induced anaphylaxis

Cefotetan is a commonly prescribed second-generation cephalosporin that acts against a wide range of bacteria. However, cefotetan-induced hypersensitivity has rarely been reported. We report 2 cases of cefotetan-induced anaphylaxis with immunologic evaluation. The first case was a 70-year-old asthmatic woman who had dyspnea and hypotension during administration of cefotetan, in which high serum-specific IgE to cefotetan-human serum albumin (HSA) conjugate was detected by enzyme-linked immunosorbent assay. The second case was a 63-year-old asthmatic woman who complained of chest tightness and dyspnea during cefotetan infusion, in which high serum-specific IgG1 and IgG4 with no serum specific IgE to cefotetan-HSA conjugate was detected. The basophil activation test using basophils from the patient showed a significant up-regulation of CD63 with the addition of anti-IgG4 antibody compared with that in non-atopic healthy controls. In conclusion, cefotetan can induce anaphylaxis, which may involve both IgE- and IgG4-mediated responses in the pathogenic mechanism.

Natural evolution of skin-test sensitivity in patients with IgE-mediated hypersensitivity to cephalosporins

There are studies demonstrating that skin-test sensitivity to penicillins can decrease over time and that allergic patients may lose sensitivity if the responsible compounds are avoided. With regard to subjects with IgE-mediated hypersensitivity to cephalosporins, however, such studies are lacking. We evaluated prospectively in a 5-year follow-up 72 cephalosporin-allergic patients. After the first evaluation, patients were classified into two groups according to their patterns of allergologic-test positivity: to both penicillins and cephalosporins (group A), or only to cephalosporins (group B). Skin tests and serum-specific IgE assays were repeated 1 year later and, in case of persistent positivity, 3 and 5 years after the first allergologic examination. Seven (43.7%) of the 16 subjects of group A and 38 (67.8%) of the 56 patients of group B became negative; one was lost to follow-up. Patients of group B became negative sooner and more frequently than group A subjects.

Antibiotic allergy

Although allergy to β-lactam and non-β-lactam antibiotics is commonly claimed, true allergy to these drugs is often absent. Reactions to antibiotics can be classified according to the interval between the last administration of the drug and the onset of symptoms, but except for immediate reactions occurring within an hour of exposure, which are almost always either IgE-mediated or due to direct stimulation of mast cells, reactions occurring later than 1 hour probably have multiple mechanisms, including being IgE-mediated or involving cell-mediated reactions. The latter are likely caused by drug-specific T lymphocytes. The diagnosis of antibiotic allergy can be difficult.

Skin testing only with penicillin G in children with a history of penicillin allergy

BACKGROUND

The absence of commercially available penicilloyl-polylysine (PPL) for most of the last decade severely hampered the practice of penicillin allergy evaluation because skin testing without PPL is reported to have a poor negative predictive value (NPV).

OBJECTIVE

To determine the safety and NPV of skin testing without PPL using only penicillin G followed by a 3-dose graded challenge to the incriminated penicillin in children with a history of penicillin allergy.

METHODS

Patients evaluated for a history of penicillin allergy at the CHU Sainte-Justine Allergy Clinic between December 2006 and December 2009 were skin tested only with penicillin G and underwent a 3-dose graded challenge to the culprit penicillin if the skin test result was negative.

RESULTS

Among 563 patients skin tested to penicillin G, 185 (33%) had a positive skin test result. These patients had a shorter interval between the initial reaction and skin testing compared with patients with a negative skin test result (P = .03). A total of 375 of 378 patients (99%) with a negative skin test result were challenged and 18 (4.8%) reacted, translating into a NPV of 95.2% (95% confidence interval [CI], 92.5%-97.1%). Three of 17 patients with a history of anaphylaxis and a negative skin test result reacted to challenge (NPV, 82.4%; 95% CI, 59.0-93.8%). All challenge reactions were mild and resolved promptly with treatment.

CONCLUSION

Among children with a history of penicillin allergy, skin testing only with penicillin G followed by a 3-dose graded challenge to the incriminated penicillin is safe and yields a good NPV. This approach could be useful when PPL is unavailable.

Skin testing and patch testing in non-IgE-mediated drug allergy

Drug skin tests can reproduce delayed hypersensitivity to drugs and entail a moderate reexposure of patients to offending drugs. Drug patch tests (DPTs) and prick tests can be done with any commercialized form of a drug. In non-severe delayed non-IgE-mediated reactions to drugs, intradermal tests (IDT) with delayed readings have a greater value, but their techniques lack standardization. A negative drug skin test does not exclude the responsibility of a drug, and the drug must be rechallenged in non-severe cases. DPTs are useful in maculopapular rashes, flexural exanthemas, and if done in situ, also in fixed drug eruption. Their best indication is in acute generalized exanthematous pustulosis or drug reaction with eosinophilia and systemic symptoms (DRESS). They should be carried out cautiously, following strict guidelines. Prick tests have a low value but they can sometimes be positive on delayed readings. In non-severe delayed reactions to drugs, intradermal tests with delayed readings are the most sensitive skin tests especially for beta-lactam antibiotics, radiocontrast media, heparins but also some biological agents. The value of patch testing varies according to the implicated drug and the non-immediate adverse drug reaction. In DRESS, DPTs have a good value in testing carbamazepine or proton pump inhibitors but remain negative in testing with allopurinol or salazopyrin. In toxic epidermal necrolysis, DPTs are safe but positive in only 9 to 23 % of the reported cases.

Antimicrobial stewardship's new weapon? A review of antibiotic allergy and pathways to 'de-labeling'

PURPOSE OF REVIEW

The continued emergence of multiresistant pathogens and widespread antimicrobial use has led to a greater emphasis on antimicrobial stewardship programs. Concurrently, an increased awareness of the rising number of antibiotic allergy labels and impact on antimicrobial use has surfaced. The integration of antibiotic allergy de-labeling and antimicrobial stewardship programs may be a pathway worthy of further focus and investigation.

RECENT FINDINGS

Recent literature has evaluated the efficacy of antibiotic allergy management (historical de-labeling, in-vitro testing, skin prick testing, intradermal testing, and oral challenges) and impact of antibiotic allergy labels on patient outcome. The importance of true and perceived antibiotic allergy cross-reactivity in the setting of β-lactam allergies has been highlighted. The impact of dedicated antibiotic allergy de-labeling clinics, inpatient antibiotic allergy testing, and integrated antimicrobial stewardship programs has been recently appraised.

SUMMARY

More recent literature supports that appropriate antibiotic allergy in-vitro and in-vivo testing and subsequent antibiotic allergy de-labeling, particularly in regard to β-lactams, can decrease broad-spectrum antibiotic use, costs, patient length of stay, and mortality. Integration of antibiotic allergy management into the decision support systems of inpatient and outpatient antimicrobial stewardship programs represents an important opportunity to further improve measured outcomes from antibiotic utilization.

Penicillin allergy evaluation: experience from a drug allergy clinic in an Arabian Gulf Country, Kuwait

BACKGROUND

Hypersensitivity to penicillin has been studied worldwide, but data regarding patterns of sensitization in Arabian Gulf countries are scarce.

OBJECTIVE

To describe the patterns of penicillin hypersensitivity during a 6-year study in Kuwait in terms of demographics, type of the culprit drug, in vivo and in vitro allergy testing.

METHODS

One hundred and twenty-four patients referred to the drug allergy clinic for penicillin allergy were fully evaluated by skin prick and intradermal testing. Drug provocation test was done on patients with negative results.

RESULTS

A total of 124 patients were evaluated for penicillin allergy. Mean age was 37.8 (standard deviation, 12.7) years, range from 8 to 74 years. Thirty-nine male (31.5%) and 85 female patients (68.5%) were included. Diagnosis of penicillin allergy was confirmed in 46 patients (37.1%). Among the 44 confirmed allergic patients by skin evaluation we had 15 (34.1%) positive skin prick test, and 29 (65.9%) positive intradermal testing. Among patients with positive skin testing, 47.7% were positive to major determinant benzylpenicilloyl poly-L-lysine, 20.4% to minor determinant mixture, 50.0% to penicillin G and 40.9% to ampicillin; 13.6% of patients were positive to amoxicillin by skin prick test. One patient had a positive radioallergosorbent test and one had a positive challenge test.

CONCLUSION

Penicillin allergy is a common problem with an incidence of about one third in our study subjects.

Antibiotic allergies in children and adults: from clinical symptoms to skin testing diagnosis

Hypersensitivity reactions to β-lactam and non-β-lactam antibiotics are commonly reported. They can be classified as immediate or nonimmediate according to the time interval between the last drug administration and their onset. Immediate reactions occur within 1 hour after the last drug administration and are manifested clinically by urticaria and/or angioedema, rhinitis, bronchospasm, and anaphylactic shock; they may be mediated by specific IgE-antibodies. Nonimmediate reactions occur more than 1 hour after the last drug administration. The most common manifestations are maculopapular exanthems; specific T lymphocytes may be involved in this type of manifestation. The diagnostic evaluation of hypersensitivity reactions to antibiotics is usually complex. The patient's history is fundamental; the allergic examination is based mainly on in vivo tests selected on the basis of the clinical features and the type of reaction, immediate or nonimmediate. Immediate reactions can be assessed by immediate-reading skin tests and, in selected cases, drug provocation tests. Nonimmediate reactions can be assessed by delayed-reading skin tests, patch tests, and drug provocation tests. However, skin tests have been well validated mainly for β-lactams but less for other classes of antibiotics.

International Consensus on drug allergy

When drug reactions resembling allergy occur, they are called drug hypersensitivity reactions (DHRs) before showing the evidence of either drug-specific antibodies or T cells. DHRs may be allergic or nonallergic in nature, with drug allergies being immunologically mediated DHRs. These reactions are typically unpredictable. They can be life-threatening, may require or prolong hospitalization, and may necessitate changes in subsequent therapy. Both underdiagnosis (due to under-reporting) and overdiagnosis (due to an overuse of the term ‘allergy’) are common. A definitive diagnosis of such reactions is required in order to institute adequate treatment options and proper preventive measures. Misclassification based solely on the DHR history without further testing may affect treatment options, result in adverse consequences, and lead to the use of more-expensive or less-effective drugs, in contrast to patients who had undergone a complete drug allergy workup. Several guidelines and/or consensus documents on general or specific drug class-induced DHRs are available to support the medical decision process. The use of standardized systematic approaches for the diagnosis and management of DHRs carries the potential to improve outcomes and should thus be disseminated and implemented. Consequently, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the European Academy of Allergy and Clinical Immunology (EAACI), the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), and the World Allergy Organization (WAO), has decided to issue an International CONsensus (ICON) on drug allergy. The purpose of this document is to highlight the key messages that are common to many of the existing guidelines, while critically reviewing and commenting on any differences and deficiencies of evidence, thus providing a comprehensive reference document for the diagnosis and management of DHRs.

Study of protein haptenation by amoxicillin through the use of a biotinylated antibiotic

Allergic reactions towards β-lactam antibiotics pose an important clinical problem. The ability of small molecules, such as a β-lactams, to bind covalently to proteins, in a process known as haptenation, is considered necessary for induction of a specific immunological response. Identification of the proteins modified by β-lactams and elucidation of the relevance of this process in allergic reactions requires sensitive tools. Here we describe the preparation and characterization of a biotinylated amoxicillin analog (AX-B) as a tool for the study of protein haptenation by amoxicillin (AX). AX-B, obtained by the inclusion of a biotin moiety at the lateral chain of AX, showed a chemical reactivity identical to AX. Covalent modification of proteins by AX-B was reduced by excess AX and vice versa, suggesting competition for binding to the same targets. From an immunological point of view, AX and AX-B behaved similarly in RAST inhibition studies with sera of patients with non-selective allergy towards β-lactams, whereas, as expected, competition by AX-B was poorer with sera of AX-selective patients, which recognize AX lateral chain. Use of AX-B followed by biotin detection allowed the observation of human serum albumin (HSA) modification by concentrations 100-fold lower that when using AX followed by immunological detection. Incubation of human serum with AX-B led to the haptenation of all of the previously identified major AX targets. In addition, some new targets could be detected. Interestingly, AX-B allowed the detection of intracellular protein adducts, which showed a cell type-specific pattern. This opens the possibility of following the formation and fate of AX-B adducts in cells. Thus, AX-B may constitute a valuable tool for the identification of AX targets with high sensitivity as well as for the elucidation of the mechanisms involved in allergy towards β-lactams.

Contributions of pharmacogenetics and transcriptomics to the understanding of the hypersensitivity drug reactions

Hypersensitivity drug reactions (HDRs) represent a large and important health problem, affecting many patients and leading to a variety of clinical entities, some of which can be life-threatening. The culprit drugs include commonly used medications including antibiotics and NSAIDs. Nontherapeutical agents, such as contrast media, are also involved. Because the pathophysiological mechanisms are not well known and the current diagnostic procedures are somewhat insufficient, new approaches are needed for understanding the complexity of HDRs. Histochemical and molecular biology studies have enabled us to classify these reactions more precisely. Pharmacogenetics has led to the identification of several genes, involved mainly in T-cell-dependent responses, with a number of markers being replicated in different studies. These markers are now being considered as potential targets for reducing the number of HDRs. Transcriptomic approaches have also been used to investigate HDRs by identifying genes that show different patterns of expression in a number of clinical entities. This information can be of value for further elucidation of the mechanisms involved. Although first studies were performed using RT-PCR analysis to monitor the acute phase of the reaction, nowadays high-density expression platforms represent a more integrative way for providing a complete view of gene expression. By combining a detailed and precise clinical description with information obtained by these approaches, we will obtain a better understanding and management of patients with HDRs.

Diagnostic evaluation of hypersensitivity reactions to beta-lactam antibiotics in a large population of children

INTRODUCTION

Hypersensitivity reactions to beta-lactams (BLs) are often reported in children, with amoxicillin and, to a lesser extent, cephalosporins being the most frequent drugs involved. Although many of these children are considered to be allergic, a careful evaluation only confirms a low percentage.

OBJECTIVES

To analyse the clinical data, sensitization profile and diagnostic methods used in a large group of children with a clinical history of hypersensitivity reactions to BLs.

METHODS

The study included children aged 1-14 yr with symptoms suggestive of hypersensitivity to BLs from January 2006-December 2012. Diagnosis was confirmed from a clinical history, specific IgE determination, skin testing and, if necessary, a drug provocation test (DPT).

RESULTS

Of a total of 783 patients studied, only 62 (7.92%) were confirmed as being allergic, 9 (14.52%) with immediate and 53 (85.48%) with non-immediate reactions. In those with immediate reactions, 2 (22.22%) were diagnosed by in vitro test, 2 (22.22%) by skin testing and 5 (55.56%) by DPT; in those with non-immediate reactions, 2 (3.77%) were diagnosed by skin testing and 51 (96.23%) by DPT. In all cases, DPT was positive to the culprit drug (29 AX-CLV, 26 AX, 1 cefixime and 1 cefaclor), and the most usual symptoms were exanthema in 43 cases, urticaria in 12, urticaria-angio-oedema in 1 and erythema in 1 case.

CONCLUSION

After an allergological work-up, over 90% of the children evaluated were finally confirmed as tolerant to BLs. Most reactions were of the non-immediate type, and DPT was an essential tool for diagnosis.

Hypersensitivity reactions to beta-lactams

Beta-lactam antibiotics (BLs) are the most frequent cause of hypersensitivity reactions mediated by specific immunological mechanisms, with two main types, IgE reactions or T-cell-dependent responses. From a practical point of view, these reactions can be classified into immediate, for those appearing within 1 h after drug intake, and non-immediate, for those appearing at least 1 h after and usually within 24 h of BL administration. The clinical symptoms differ according to this classification. Urticaria and anaphylaxis are the most frequently recorded symptoms in immediate reactions and maculopapular exanthema and delayed urticaria in non-immediate reactions. Although the exact diagnostic approach differs depending on the underlying mechanism, it is based on the performance of skin testing, laboratory tests, and drug provocation tests.T cells are a key factor in all types of hypersensitivity reactions to BLs, regulating both IgE production or acting as effector cells, with a different profile of cytokine production. A Th1 pattern is observed in both CD4(+) and CD8(+) peripheral T cells in non-immediate reactions, whereas a Th2 pattern is expressed in CD4(+) T cells in immediate reactions.

Activation of the TCR complex by small chemical compounds

Small chemical compounds and certain metal ions can activate T cells, resulting in drug hypersensitivity reactions that are a main problem in pharmacology. Mostly, the drugs generate new antigenic epitopes on peptide-major histocompatibility complex (MHC) molecules that are recognized by the T-cell antigen receptor (TCR). In this review we discuss the molecular mechanisms of how the drugs alter self-peptide-MHC, so that neo-antigens are produced. This includes (1) haptens covalently bound to peptides presented by MHC, (2) metal ions and drugs that non-covalently bridge self-pMHC to the TCR, and (3) drugs that allow self-peptides to be presented by MHCs that otherwise are not presented. We also briefly discuss how a second signal-next to the TCR-that naïve T cells require to become activated is generated in the drug hypersensitivity reactions.

Late-onset bolus intravenous beta-lactam antibiotic adverse reaction: short-lived symptoms during drug administration and associated laboratory abnormalities

BACKGROUND

In the 1970s, there were 2 reports of a late-onset adverse reaction during bolus infusions of benzyl penicillin, characterized by short-lived symptoms, most commonly abdominal pain. The mechanism is not known. We set out to further characterize this reaction.

METHODS

We conducted a prospective observational study of all adult patients receiving bolus intravenous (IV) beta-lactam antibiotics under the care of our Outpatient IV Antibiotic Service from 1 August 2007 to 31 January 2010, focusing on those who developed infusion-related symptoms.

RESULTS

During the 30-month study, 11 of the 163 patients (7%) treated with bolus IV beta-lactam antibiotics developed a late-onset infusion-related adverse reaction. Six of 30 patients (20%) treated with benzyl penicillin developed this adverse reaction compared to 5 of 133 (4%) treated with any other beta-lactam antibiotic (p = 0.006). The median duration of beta-lactam antibiotic before reaction onset was 25 days. Abdominal pain occurred in 9 patients (82%), fever in 3 (27%), and rash in 5 (45%). Seven patients (64%) developed a combination of thrombocytopenia, neutropenia, and/or lymphopenia and 6 (55%), elevated liver enzymes.

CONCLUSIONS

This adverse reaction, occurring late during prolonged IV bolus beta-lactam treatment, is most often characterized by short-lived abdominal pain occurring at the time of infusion and is more common in patients receiving benzyl penicillin. It is frequently associated with cytopenias and elevated liver enzymes. It may have both immunological and non-immunological mechanisms.

Recent applications of basophil activation tests in the diagnosis of drug hypersensitivity

Immediate-type drug hypersensitivity is an increasingly significant clinical issue; however, the diagnosis is frequently hindered due to lack of safe and precise diagnostic tests. Flow cytometry-assisted basophil activation test is a safe in vitro diagnostic tool for assessing basophil activation upon allergen stimulation. In this review, we have summarized current literature on the diagnostic utilities, new indications, and methodological aspects of the basophil activation test for the diagnosis of drug hypersensitivity.

Synergistic effect between amoxicillin and TLR ligands on dendritic cells from amoxicillin-delayed allergic patients

Amoxicillin, a low-molecular-weight compound, is able to interact with dendritic cells inducing semi-maturation in vitro. Specific antigens and TLR ligands can synergistically interact with dendritic cells (DC), leading to complete maturation and more efficient T-cell stimulation. The aim of the study was to evaluate the synergistic effect of amoxicillin and the TLR2, 4 and 7/8 agonists (PAM, LPS and R848, respectively) in TLR expression, DC maturation and specific T-cell response in patients with delayed-type hypersensitivity (DTH) reactions to amoxicillin. Monocyte-derived DC from 15 patients with DTH to amoxicillin and 15 controls were cultured with amoxicillin in the presence or absence of TLR2, 4 and 7/8 agonists (PAM, LPS and R848, respectively). We studied TLR1-9 gene expression by RT-qPCR, and DC maturation, lymphocyte proliferation and cytokine production by flow cytometry. DC from both patients and controls expressed all TLRs except TLR9. The amoxicillin plus TLR2/4 or TLR7/8 ligands showed significant differences, mainly in patients: AX+PAM+LPS induced a decrease in TLR2 and AX+R848 in TLR2, 4, 7 and 8 mRNA levels. AX+PAM+LPS significantly increased the percentage of maturation in patients (75%) vs. controls (40%) (p=0.036) and T-cell proliferation (80.7% vs. 27.3% of cases; p=0.001). Moreover, the combinations AX+PAM+LPS and AX+R848 produced a significant increase in IL-12p70 during both DC maturation and T-cell proliferation. These results indicate that in amoxicillin-induced maculopapular exanthema, the presence of different TLR agonists could be critical for the induction of the innate and adaptive immune responses and this should be taken into account when evaluating allergic reactions to these drugs.

Diagnosis of penicillin allergy revisited: the value of case history, skin testing, specific IgE and prolonged challenge

BACKGROUND

Skin testing in duplicate, correlation between case history of immediate and nonimmediate reactions and challenge outcome and prolonged oral treatment with penicillin in the diagnostic evaluation of allergic reactions to β-lactam antibiotics, mimicking real-life situations, have only been addressed in few studies.

METHODS

A total of 342 patients suspected of having β-lactam allergy were investigated according to the European Network for Drug Allergy (ENDA) guidelines and patients found to be negative in the ENDA program were supplemented with a 7-day oral treatment with penicillin. Skin testing with penicillins was performed in duplicate. Patients with case histories of reactions to other β-lactams were also subsequently challenged with the culprit drug.

RESULTS

Nineteen patients were IgE-sensitized to penicillin. Then, intracutaneous tests (ICTs) were performed, in which 35 patients tested positive for allergy, 21 with delayed and 14 with immediate reactions. Only three patients tested positive for the major (PPL) and/or minor (MDM) penicillin determinants, all being positive for penicillin G in ICT. The remaining 291 patients were challenged with penicillin: 10 tested positive in single-dose challenge and 23 tested positive in the 7-day challenge. A total of 17 of 78 patients with a negative penicillin challenge tested positive during challenges with other β-lactams. We found no correlation between case histories of immediate and nonimmediate reactions and reaction time during challenge.

CONCLUSION

The data suggest that case history is often insufficient to discriminate between immediate reactors and nonimmediate reactors. A 7-day challenge with the culprit β-lactam may yield more positive reactions than the accepted one- or 2-day challenge. Interpretation of skin testing should be made with caution.

Identification and frequency of circulating CD4(+) T lymphocytes specific to Benzylpenicillin in healthy donors

BACKGROUND

Drug hypersensitivity is known to rely on a drug-specific T-cell response. Amplitude of antigen-specific T-cell response is partly controlled by the size of the antigen-specific naïve CD4(+) T-cell repertoire, but estimate of this repertoire has never been investigated for allergenic drugs. The purpose of this study was to evaluate the frequency of benzylpenicillin-specific CD4(+) T lymphocytes in healthy donors.

METHODS

Co-cultures were established with CD4(+) T lymphocytes from healthy donors and mature autologous dendritic cells loaded with benzylpenicillin coupled to human serum albumin. CD4(+) T lymphocytes were stimulated once a week for 4 weeks with benzylpenicillin coupled to human serum albumin. The CD4(+) T-cell response was measured using an interferon-γ ELISPOT assay. Frequency of benzylpenicillin-specific naive CD4(+) T lymphocytes was then calculated using the Poisson distribution law.

RESULTS

Results showed the presence of benzylpenicillin-specific CD4(+) T lymphocytes in 9 of 10 tested healthy donors irrespective of their HLA typing, with a mean frequency of 0.29 cells per million of CD4(+) T cells. Experiments performed on naive (CD45RA(+) ) and on memory (CD45RO(+) ) CD4(+) T lymphocytes showed that these benzylpenicillin-specific CD4(+) T lymphocytes belonged to the naive T-cell subpopulation.

CONCLUSION

This study showed for the first time the existence of naive CD4(+) T lymphocytes specific to benzylpenicillin in healthy donors.

Skin test concentrations for systemically administered drugs -- an ENDA/EAACI Drug Allergy Interest Group position paper

Skin tests are of paramount importance for the evaluation of drug hypersensitivity reactions. Drug skin tests are often not carried out because of lack of concise information on specific test concentrations. The diagnosis of drug allergy is often based on history alone, which is an unreliable indicator of true hypersensitivity.To promote and standardize reproducible skin testing with safe and nonirritant drug concentrations in the clinical practice, the European Network and European Academy of Allergy and Clinical Immunology (EAACI) Interest Group on Drug Allergy has performed a literature search on skin test drug concentration in MEDLINE and EMBASE, reviewed and evaluated the literature in five languages using the GRADE system for quality of evidence and strength of recommendation. Where the literature is poor, we have taken into consideration the collective experience of the group.We recommend drug concentration for skin testing aiming to achieve a specificity of at least 95%. It has been possible to recommend specific drug concentration for betalactam antibiotics, perioperative drugs, heparins, platinum salts and radiocontrast media. For many other drugs, there is insufficient evidence to recommend appropriate drug concentration. There is urgent need for multicentre studies designed to establish and validate drug skin test concentration using standard protocols. For most drugs, sensitivity of skin testing is higher in immediate hypersensitivity compared to nonimmediate hypersensitivity.

Determining safe alternatives for multidrug hypersensitive patients with the alternative triple antibiotic-analgesic test

BACKGROUND

Drug provocation tests (DPTs) need technical equipment, staff and time. There are very few allergy centres performing DPTs in Turkey. Therefore many patients are referred to these centres. One day triple-double antibiotic or non-steroidal anti-inflammatory drug (NSAID) oral DPT for determining safe alternatives is safe, cost-effective and time saving compared to conventional one day one drug oral DPT. Our aim was to investigate the safety of antibiotic-NSAID oral DPT performed on the same day to find safe alternatives in multidrug hypersensitive patients.

METHODS

Forty-two patients who had been diagnosed as having both antibiotic and NSAID hypersensitivity were enrolled to the study between 15 November and 15 July 2010. The reactions were urticaria and/or angio-oedema not including laryngeal oedema for all patients. Two antibiotics-one NSAID or two NSAIDs-one antibiotic triple test have been performed on the same day to study patients (n=22), while the control group (n=20) had taken drugs on three separate days.

RESULTS

Only two patients had positive reactions during triple test and two patients had adverse reactions; one had gastric pain, one had nausea. Three patients in the control group had positive reactions. There were no significant differences between the two groups in frequency of adverse and allergic drug reactions (p>0.05). Sixty days were spent for the tests of the control group with only 28 days for the study population.

CONCLUSION

Triple test performed with antibiotic and NSAID on the same day for determining safe alternatives for multidrug hypersensitive patients reporting non-life-threatening allergic reactions seems to be safe and time-saving.

Skin testing for Beta-lactam antibiotics: impact of the availability of a major determinant

Beta-lactam antibiotics are very effective agents for a variety of infections. In patients with beta-lactam allergy, these drugs are withheld due to fear of subsequent allergic reactions. Therefore, increasing their exposure to broad spectrum antibiotics, which are more costly, have greater side effects, and increase the risk of developing resistant organisms. Up to 90 % of patients with a proposed beta-lactam sensitivity can tolerate beta lactam agents after appropriate evaluation. Skin testing to beta-lactam agents is the gold standard in evaluating patients with type I, immediate hypersensitivity reactions. The robust negative predictive value of this test has yet to be surpassed by any other testing modality currently available.

Drug provocation tests: up-date and novel approaches

Summary

Drug provocation tests (DPTs) are often needed when evaluating patients with suspected drug hypersensitivity reactions. General considerations on DPTs, with regard to indications, contraindications, methods, limitations and interpretations have been thoroughly addressed and various protocols are published. However, the field of drug allergy is changing and DPTs make no exception. Novel (or sometimes, simply renewed) approaches arise, awaiting to be either validated or refuted in larger studies in the future. Instead of covering the whole topic of DPTs, this paper will address these recent and challenging aspects.

Testing children for allergies: why, how, who and when: an updated statement of the European Academy of Allergy and Clinical Immunology (EAACI) Section on Pediatrics and the EAACI-Clemens von Pirquet Foundation

Allergic diseases are common in childhood and can cause a significant morbidity and impaired quality-of-life of the children and their families. Adequate allergy testing is the prerequisite for optimal care, including allergen avoidance, pharmacotherapy and immunotherapy. Children with persisting or recurrent or severe symptoms suggestive for allergy should undergo an appropriate diagnostic work-up, irrespective of their age. Adequate allergy testing may also allow defining allergic trigger in common symptoms. We provide here evidence-based guidance on when and how to test for allergy in children based on common presenting symptoms suggestive of allergic diseases.

Treatment of patients with a history of penicillin allergy in a large tertiary-care academic hospital

BACKGROUND

Prescribing antibiotics to patients with a history of penicillin allergy is common in clinical practice. Opting for non-beta-lactam antibiotics has its inconveniences and is often unnecessary, because most of these patients are in fact not allergic.

OBJECTIVE

This study aimed to determine how physicians in a large Canadian tertiary-care academic hospital without allergists on staff treat patients with a history of penicillin allergy.

METHODS

A retrospective study was conducted during a 1-year period among all patients hospitalized in the intensive care unit, coronary care unit, and internal medicine wards. Files of patients with a record of penicillin allergy were reviewed to assess the need for antibiotics during their hospitalization and the decision-making process underlying the choice of antibiotic. The additional costs of alternative antibiotics were calculated.

RESULTS

The files of 1738 patients admitted over a 1-year period were hand reviewed. A history of penicillin allergy was found in 172 patients (9.9%). The allergic reaction was described in only 30% of cases and left unmentioned in 20.7%. Beta-lactam antibiotics were used on 56 occasions despite a history of penicillin allergy. The use of alternative antibiotics in place of the beta-lactam standard of care carried an additional cost of $15,672 Canadian.

CONCLUSION

Alleged penicillin allergy is common among hospitalized patients and leads to substantial additional costs. Poor documentation of penicillin allergy likely reflects a lack of knowledge on this issue in the medical community, which impairs optimal treatment of these patients. Increased education on this matter is needed, and allergists on staff could be part of the solution.

Desensitization to antibiotics in children

Drug hypersensitivity reactions can occur to almost all drugs and antibiotics are among the most common cause for this kind of reactions. Drug hypersensitivity may affect any organ or system, and manifestations range widely in clinical severity from mild pruritus to anaphylaxis. In most cases, the suspected drug is avoided in the future. In case of infection, there is usually a safe antibiotic alternative. Nonetheless, in some cases, no alternative treatment exists for optimal therapy. Under these circumstances, desensitization may be performed. Drug desensitization is defined as the induction of a temporary state of tolerance to a drug which can only be maintained by continuous administration of the medication responsible for the hypersensitivity reaction. Desensitization is mainly performed in IgE-mediated reactions. Increasing doses of the implicated drug are administered over a short period of time, until the therapeutic dose is achieved and tolerated. Very few studies confined to children are found in literature. Most of them are case reports. In general, the proposed desensitization schemes are similar to those used in adults differing only in the final dose administered. The purpose of this study is to review desensitization to antibiotics in children presenting and discussing three clinical practical cases of desensitization in this age group.

Diagnosing multiple drug hypersensitivity in children

BACKGROUND

Multiple drug hypersensitivity (MDH) has been defined as a hypersensitivity to two or more chemically different drugs. Two types of MDH have been reported: the first one, which develops to different drugs administered simultaneously and the second type, in which sensitizations develop sequentially. In children, studies which diagnose MDH on the basis of positive allergologic tests to 2 or more chemically different drugs are lacking.

METHODS

We conducted a prospective study evaluating children with histories of MDH by skin tests, patch tests, serum-specific IgE assays, and drug provocation tests.

RESULTS

A MDH was diagnosed in 7 (2.5%) of the 279 children evaluated who completed the study. The responsible drugs were β-lactams (penicillins and cephalosporins) in 5 episodes, ibuprofen and anticonvulsants in 3, and erythromycin, fentanyl, methylprednisolone, and cotrimoxazole in 1. Sensitivity to 2 chemically different drugs was diagnosed in 6 children and to 3 drugs in 1 child. Two of the 7 children presented the first type of MDH, whereas 5 displayed the second one.

CONCLUSIONS

MDH can occur in children, even to drugs other than antibiotics. It is crucial to evaluate children with histories of MDH using both in vivo and in vitro allergologic tests, including challenges. In fact, such approach allows the physician to confirm the diagnosis of MDH in a small percentage of children with histories of MDH, as well as to rule it out in the great majority of them.

Definitions and mechanisms of drug hypersensitivity

Adverse drug reactions are a difficult problem faced by clinicians in everyday practice. The mechanisms of drug hypersensitivity are not well understood. This is reflected by difficulties in their classification, which is mainly based upon the current knowledge of immunologic and nonimmunologic mechanisms, onset of symptoms (immediate or nonimmediate) and morphology. For the individual patient, the correct diagnosis and classification is important because strict avoidance of the offending drug might be of vital importance. Considerable experience is required to guide management, to interpret results of investigations and to undertake drug challenges. This article summarizes the current knowledge regarding definitions and mechanisms. However, the field of drug hypersensitivity is rapidly expanding. Modern drugs such as biological agents bare hypersensitivity risks that are potentially mediated by, so far, unknown mechanisms.

IgE and chemotherapy

The nexus of chemotherapeutic intervention and the immunomodulation of IgE-related phenomena are not well understood. The relationship bears importance in better understanding the causal and/or resultant effects of one on the other and their collective role in the management and sequelae of the cancer patient. This review discusses the relationship of chemotherapy on immunoglobulins with a focus on IgE and other related biological processes including hypersensitivity reactions and proposes models toward effective management of the cancer patient in this regard.

Fatal adverse effects of injected ceftriaxone sodium in China

PURPOSE

The incidence of adverse reactions to ceftriaxone, which is widely used in China, has gradually increased, with an associated increase in patient fatality. An analysis of the reported data from articles published in China highlights the importance and extent of this growing public health problem.

METHODS

We identified previously reported cases of adverse effects to ceftriaxone sodium by searching the Chinese Medical Text Database System for reports published between January 2002 and December 2009. The references cited in the articles were examined for additional reports.

RESULTS

A total of 17 articles were identified that cited fatal adverse reactions in 22 cases. Most patients had been treated for upper respiratory tract infection and bronchitis and had no reported history of ceftriaxone allergy. Of the patients, 77% were treated with ceftriaxone without undergoing intradermal testing, and 36% were not offered any information on intradermal testing. Concomitant intravenous medications were prescribed in 7 cases, and an overdose of ceftriaxone sodium was prescribed for two patients. The delay between drug administration and the onset of adverse drug reactions occurred within 30 min in 72.7% of the patients. Of the deaths, 73% occurred on the first day of treatment.

CONCLUSIONS

The fatal adverse events associated with ceftriaxone occurred because of inappropriate drug usage, drug overdoses, careless medical personnel, poor medical conditions, and possibly poor drug quality. Although some deaths may be unavoidable, the risks can be minimized by the appropriate administration of ceftriaxone and further consultation with the Chinese medical profession and research.

Comprehensive allergy work-up is mandatory in cystic fibrosis patients who report a history suggestive of drug allergy to beta-lactam antibiotics

BACKGROUND

In the general population, reports on suspected ß-lactam hypersensitivity are common. After a drug allergy work-up at best 20% of the selected patients are positive. However, these considerations have not been explored in cystic fibrosis patients for whom antibiotics are even more crucial.

METHODS

The study, part of the Drug Allergy and Hypersensitivity (DAHD) cohort, was performed in the regional cystic fibrosis center of Montpellier, France. After identifying patients with a clinical history suggestive of drug allergy to ß-lactams, a complete drug allergy work-up, was carried out according to the EAACI recommendations.

RESULTS

Among the 171 patients involved, 23 reported clinical manifestations potentially compatible with a drug allergy to ß-lactams. After performing the complete drug-allergy work-up, 7 were considered as drug hypersensitive (3 had positive skin tests, 1 a positive provocation test, 3 declined the tests). Excluding the latter 3 patients with incomplete drug allergy work-up, the rate of proven drug allergy was 2.3%.

CONCLUSIONS

Drug allergy to ß-lactams in cystic fibrosis patients is of importance. A full drug allergy work-up is mandatory in case of suspicion, because ß-lactam responsibility is often ruled out.

The association between DRESS and the diminished numbers of peripheral B lymphocytes and natural killer cells

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a drug-induced, severe multiorgan system reaction whose exact pathogenesis remains unknown. This study aimed at evaluating specific changes in peripheral blood lymphocyte subtypes associated with DRESS during antibiotic treatment. We analyzed six patients with DRESS. A complete blood count and peripheral blood lymphocytes immunophenotyping were carried out at symptom onset and at follow-up visits. Acute-phase reactants and liver enzymes were measured in all patients. Other tests - viral serology, serum immunoglobulin levels, and skin tests were performed when possible. B-cell counts were low in all patients at the onset of DRESS, and natural killer (NK) cells were low in all cases except one. During recovery, B-cell numbers were within a normal range in five patients. In one, there was even a 10-fold increase in B-cell counts, although the level was mildly low after 3 months. NK-cell numbers were within a normal range in three patients. The mean numbers of B cells and NK cells were significantly higher in the second samples compared to the values on admission. Serum IgA and IgM levels were low in one patient. The drug provocation test was positive with cefotaxime in one patient. Viral serology, performed on five patients, was negative. A decrease in B-cell and NK-cell counts was the most consistent finding associated with the onset of antibiotic-induced DRESS in our patients. This immunologic alteration might be a useful predictor of DRESS development.