Clinical history as a predictor of penicillin skin test outcome

Frequency of severe reactions following penicillin drug provocation tests: A Bayesian meta-analysis

BACKGROUND

Patients with a penicillin allergy label tend to have worse clinical outcomes and increased healthcare use. Drug provocation tests (DPT) are the gold-standard in the diagnostic workup of penicillin allergy, but safety concerns may hinder their performance. We aimed to assess the frequency of severe reactions following a DPT in patients with reported allergy to penicillins or other β-lactams.

METHODS

We performed a systematic review, searching MEDLINE, Scopus, and Web of Science. We included primary studies assessing participants with a penicillin allergy label who underwent a DPT. We performed a Bayesian meta-analysis to estimate the pooled frequency of severe reactions to penicillin DPTs. Sources of heterogeneity were explored by subgroup and metaregression analyses.

RESULTS

We included 112 primary studies which included a total of 26,595 participants. The pooled frequency of severe reactions was estimated at 0.06% (95% credible interval [95% CrI] = 0.01%-0.13%; I2  = 57.9%). Most severe reactions (80/93; 86.0%) consisted of anaphylaxis. Compared to studies where the index reaction was immediate, we observed a lower frequency of severe reactions for studies assessing non-immediate index reactions (OR = 0.05; 95% CrI = 0-0.31). Patients reporting anaphylaxis as their index reaction were found to be at increased risk of developing severe reactions (OR = 13.5; 95% CrI = 7.7-21.5; I2  = 0.3%). Performance of direct DPTs in low-risk patients or testing with the suspected culprit drug were not associated with clinically relevant increased risk of severe reactions.

CONCLUSIONS

In patients with a penicillin allergy label, severe reactions resulting from DPTs are rare. Therefore, except for patients with potentially life-threatening index reactions or patients with positive skin tests-who were mostly not assessed in this analysis -, the safety of DPTs supports their performance in the diagnostic assessment of penicillin allergy.

β-lactam exposure outcome among patients with a documented allergy to penicillins post-implementation of a new electronic medical record system and alerting rules

BACKGROUND

Recent studies suggest that type I hypersensitivity cross-reactivity between β-lactam antibiotics is due to side chain similarity and not the common β-lactam ring. As a result, the prescriber-alerting rules of an electronic medical record (EMR) system were adjusted to only flag prescribers when prescribing penicillins or β-lactams with similar side chains (viz, cephalexin, cefadroxil, and cefoxitin) to patients with a documented allergy to penicillins. This study was conducted to assess and confirm the safety of the adjusted alerting rules; the primary outcome was the prevalence of anaphylaxis on β-lactam re-exposure.

METHODS

Retrospective chart review was conducted for patients who, under the reformed alerting rules, received a β-lactam antibiotic post-documentation of an allergy to penicillins in their EMR from April 2018 to July 2019 at a 268-bed community hospital. Given the volume of eligible patients, a 25% sample was randomly selected for review from initiation of the β-lactam antibiotic up to 30 days post-exposure to determine the prevalence of anaphylaxis.

RESULTS

Of the 325 charts reviewed, 300 patients (92.3%) received a β-lactam antibiotic with a different side chain than penicillins (not alerted on prescribing). Chart review of these 300 patients confirmed no reports of anaphylaxis secondary to β-lactam exposure (0%), and two patients developed non-anaphylactic delayed reactions (rash).

CONCLUSIONS

There were no reports of immediate life-threatening anaphylaxis under the reformed alerting rules, despite 25 patients (7.7%) receiving an alerted drug, such as piperacillin-tazobactam. The reformed alerting rules better reflect current literature and reduce the risk of prescriber-alerting fatigue without compromising patient safety. The occurrence of delayed reactions reinforced the need to monitor for these reactions on β-lactam antibiotic prescribing.

Clinical history in suspected cases of immediate allergy to beta-lactam

Background

Mislabeling patients as allergic to beta lactams poses an increased risk of morbidity, healthcare costs, and even mortality. This study aimed to define the accuracy of medical history, taken by a specialist, in diagnosing immediate reaction to beta lactams.

Methods

All patients labeled as allergic to beta lactam were interviewed by a specialist in allergy and clinical immunology and defined as suspected of having a history of immediate or non-immediate reaction. When indicated, skin tests to major and minor determinants and oral graded challenge to the culprit drug were performed.

Results

A total of 909 patients were evaluated. A total of 798 (87.7%) were labeled as allergic to penicillin. In 108 (11.9%) cases, the allergist suspected an immediate reaction based on clinical history. Skin test or challenge proven diagnosis of IgE-mediated allergy to beta lactam were significantly more prevalent in the group with an allergist's suspicion of an immediate allergy (23.1% vs. 5%, p < 0.01). The sensitivity and negative predictive values of an anamnesis of immediate reaction were high (0.9 and 0.95, respectively), but the specificity and positive predictive value were low (0.37 and 0.23, respectively).

Conclusion

Medical history taken by an allergist can exclude immediate hypersensitivity reaction, but it is not specific enough to confirm the diagnosis. Skin testing and graded challenge in suspected cases of immediate hypersensitivity reaction are indicated.

β-Lactam allergy testing and delabeling-Experiences and lessons from Singapore

Background

β‐Lactam allergy is over‐reported and this leads to greater healthcare costs. Allergy testing has inherent risks, yet patients who test negative may continue avoiding β‐lactams.

Objective

To evaluate the safety and diagnostic value of β‐lactams allergy testing locally and usage of antibiotics following negative testing.

Methods

We performed a retrospective medical record review and follow‐up survey of patients who underwent β‐lactam testing between 2010 and 2016 at the National Skin Centre, Singapore.

Results

We reviewed the records of 166 patients, with a total of 173 β‐lactam allergy labels. Eighty (46.2%) labels were to penicillin, 75 (43.1%) to amoxicillin/amoxicillin‐clavulanic acid, 11 (6.4%) to cephalexin, and 5 (2.9%) to others. Skin tests were performed in 142 patients and drug provocation tests (DPTs) in 141 patients. Eleven (6.6%) patients defaulted DPTs after skin testing. Out of 166 patients, 22 (13.3%) patients were proven allergic by either skin tests (16) or DPTs (6). Patients who tested positive had nonsevere reactions.

Out of 155 patients who were conclusively evaluated, 133 (85.8%) were not allergic. Of these patients, 30 (22.6%) used the tested β‐lactam subsequently, with one reporting a mild reaction. Fifty‐one (38.3%) patients were uncontactable or uncertain if they consumed a β‐lactam since testing negative. Fifty‐two (39.1%) patients had no re‐exposure (35 had no indication, 17 were fearful of reactions).

Conclusion

Drug allergy testing was safe and removed inappropriate labels.

Clinical Implication

Allergy testing is efficacious, but fears of subsequent rechallenge should be addressed to maximize the effectiveness of allergy delabeling.

Accuracy of penicillin allergy diagnostic tests: A systematic review and meta-analysis

BACKGROUND

Having a penicillin allergy label associates with a higher risk for antibiotic resistance and increased health care use.

OBJECTIVE

We sought to assess the accuracy of skin tests and specific IgE quantification in the diagnostic evaluation of patients reporting a penicillin/β-lactam allergy.

METHODS

We performed a systematic review and diagnostic accuracy meta-analysis, searching on MEDLINE, Scopus, and Web of Science. We included studies conducted in patients reporting a penicillin allergy and in whom skin tests and/or specific IgE quantification were performed and compared with drug challenge results. We quantitatively assessed the accuracy of diagnostic tests with bivariate random-effects meta-analyses. Meta-regression and subgroup analyses were performed to explore causes of heterogeneity. Studies' quality was evaluated using QUADAS-2 criteria.

RESULTS

We included 105 primary studies, assessing 31,761 participants. Twenty-seven studies were assessed by bivariate meta-analysis. Skin tests had a summary sensitivity of 30.7% (95% CI, 18.9%-45.9%) and a specificity of 96.8% (95% CI, 94.2%-98.3%), with a partial area under the summary receiver-operating characteristic curve of 0.686 (I² = 38.2%). Similar results were observed for subanalyses restricted to patients reporting nonimmediate maculopapular exanthema or urticaria/angioedema. Specific IgE had a summary sensitivity of 19.3% (95% CI, 12.0%-29.4%) and a specificity of 97.4% (95% CI, 95.2%-98.6%), with a partial area under the summary receiver-operating characteristic curve of 0.420 (I² = 8.5%). Projected predictive values mainly reflect the low frequency of true penicillin allergy.

CONCLUSIONS

Skin tests and specific IgE quantification appear to have low sensitivity and high specificity. Because current evidence is insufficient for assessing the role of these tests in stratifying patients for delabeling, we identified key requirements needed for future studies.

A Closer Look at Penicillin Allergy History: Systematic Review and Meta-Analysis of Tolerance to Drug Challenge

BACKGROUND

True allergy to penicillin is rare, despite the high frequency with which it is reported. While most patients reporting penicillin allergy are not prone to anaphylaxis, it is not currently known what percentage of these patients will tolerate dose challenges of penicillin-based antibiotics. This review aims to determine the rate of tolerance in patients reporting penicillin allergy when challenged with penicillin-based antibiotics.

METHODS

We searched MedLine, Embase, and Cochrane Library for publications with English language translations between the years 2000 and 2017. We included randomized controlled trials, quasi-experimental, and observational studies of participants reporting penicillin allergy who received at least one systemic dose of a penicillin in the form of a drug challenge. At least 2 independent reviewers extracted data from included studies and assessed the quality of each included study. To generate primary outcome data, we calculated a summary estimate rate of penicillin tolerance from a pooled proportion of participants receiving penicillin with no adverse effects.

RESULTS

Initial literature search yielded 2945 studies, of which 23 studies were ultimately included in our review; 5056 study participants with reported history of penicillin allergy were challenged with a penicillin. After weighting for study sample size, a pooled average of 94.4% (95% confidence interval, 93.7%-95%) of participants tolerated the dose challenge without any adverse reaction.

CONCLUSION

Misrepresented penicillin allergy drives unnecessary use of alternative antibiotics, which may be less effective, more toxic, and more expensive than using penicillin. In addressing the problem of penicillin allergy over-diagnosis, evaluation should go beyond risk for type 1 hypersensitivity. Our data suggest that 94.4% of 5056 participants with reported penicillin allergy determined to be clinically appropriate for allergy evaluation tolerated repeat administration of penicillin-based antibiotics without any adverse reactions. This review generates meaningful information useful to clinical predictive analytics, in evaluating and managing patients with a reported history of penicillin allergy.

A novel whole blood based method for lymphocyte transformation test in drug allergies

Drug allergies pose a great deal of danger for the patients. It hinders effective treatment procedures in hospitalized patients. Moreover, it complicates the symptoms due to the allergic reactions of the immune system. Allergic reactions may arise against any medication including antibiotics and chemotherapeutics. Therefore, it is crucial to assess the sensitization pattern of the patients to culprit drug(s) before retreatment with the same or similar drug, or in order to confirm/exclude a suspected drug hypersensitivity reaction. In vivo and in vitro tests are performed in the evaluation of patients. Current methods of in vitro drug allergy evaluations rely on time consuming and expensive methods. Ficoll separation of peripheral blood mononuclear cells, their activation with stimulants in the presence of the drug of interest, CD69 or CD25 or BrdU or radioactive thymidine analysis of the cells after a couple of days of incubation is an excessively elaborate work and also uneconomical. Moreover, it requires a great deal of expertise to interpret the results. Here, we are reporting a new whole blood based lymphocyte transformation test method that does not require ficoll separation, CD69, CD25, BrdU and radioactive thymidine analysis. Thanks to the color change in the whole blood itself one can easily determine the allergic reaction to a certain drug. This new method is less time consuming, more economical and easy to apply.

Anaphylaxis for Internists: Definition, Evaluation, and Management, with a Focus on Commonly Encountered Problems

Anaphylaxis is an acute systemic allergic reaction that can be life threatening. In adults, the most common causes of anaphylaxis are foods, drugs, and insect stings. This article reviews the definition, classification, evaluation, differential diagnosis, prognosis, complications, and management of anaphylaxis. Tailored for internists, the article focuses on anaphylactic medication allergies. It provides a guide to optimally evaluate and manage patients with antibiotic allergy using a simple, rapid risk stratification technique, graded antibiotic challenge (test dose), and/or allergist-guided drug desensitization. It also reviews other causes of anaphylaxis that internists are likely to encounter, and an approach to their management.

De-labeling of β-lactam allergy reduces intraoperative time and optimizes choice in antibiotic prophylaxis

BACKGROUND

Suspected penicillin allergic individuals receive suboptimal non-β-lactams for intraoperative prophylaxis which may prolong operations and have negative clinical outcomes. We therefore studied if β-lactam de-labeling optimized choice of prophylactic antibiotics and improved intraoperative time efficiency.

METHODS

A multistep approach was used. It included a risk assessment tool by an allergist, β-lactam skin testing and oral provocation. To determine the value of de-labeling, we appraised intraoperative antibiotic choices and correlated them with time to first incision.

RESULTS

A total of 194 patients were evaluated preoperatively. Four patients were diagnosed β-lactam allergic on skin testing. Of the remaining 190 skin test negative patients, 146 were β-lactam challenged. Only 5% reacted and were considered β-lactam allergic. Cefazolin became the perioperative antibiotic of choice for 77% of patients requiring antibiotic prophylaxis. Only 5 confirmed β-lactam allergic patients received intraoperative vancomycin. Patients avoiding use of vancomycin saved an average of 22 minutes in operative time. Of the 44 patients not having a β-lactam challenge, 36 received antibiotics and 18 (50%) of these were prescribed intraoperative cefazolin.

CONCLUSION

Using this three step process, almost all of those claiming penicillin allergy were de-labeled. In most patients that were drug challenged, β-lactam antibiotics became the perioperative drug of choice. In cases where oral challenge was not used in the assessment only 50% were given a β-lactam. The reduced use of vancomycin minimized delays in initiation of incision time, thus improving operative efficiency. Ultimately, randomized controlled studies are required to objectively determine the effectiveness of this approach.

A clinical decision-making algorithm for penicillin allergy

BACKGROUND

About 10% of subjects report suspected penicillin allergy, but 85-90% of these patients are not truly allergic and could safely receive beta-lactam antibiotics Objective: To design and validate a clinical decision-making algorithm, based on anamnesis (chronology, severity, and duration of the suspected allergic reactions) and reaching a 100% sensitivity and negative predictive value, to assess allergy risk related to a penicillin prescription in general practise.

STUDY DESIGN AND METHODS

All patients were included prospectively and explorated based on ENDA/EAACI recommendations. Results of penicillin allergy work-up (gold standard) were compared with results of the algorithm.

RESULTS

Allergological work-up diagnosed penicillin hypersensitivity in 41/259 patients (15.8%) [95% CI: 11.5-20.3]. Three of these patients were diagnosed as having immediate-type hypersensitivity to penicillin, but had been misdiagnosed as low risk patients using the clinical algorithm. Thus, the sensitivity and negative predictive value of the algorithm were 92.7% [95% CI: 80.1-98.5] and 96.3% [95% CI: 89.6-99.2], respectively, and the probability that a patient with true penicillin allergy had been misclassified was 3.7% [95% CI: 0.8-10.4].

CONCLUSIONS

Although the risk of misclassification is low, we cannot recommend the use of this algorithm in general practice. However, the algorithm can be useful in emergency situations in hospital settings. Key messages True penicillin allergy is considerably lower than alleged penicillin allergy (15.8%; 41 of the 259 patients with suspected penicillin allergy). A clinical algorithm based on the patient's clinical history of the supposed allergic event to penicillin misclassified 3/41 (3.7%) truly allergic patients.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

Association between chronic urticaria and self-reported penicillin allergy

BACKGROUND

Penicillin allergy is the most commonly reported drug allergy and often presents with cutaneous symptoms. Other common diagnoses, such as chronic urticaria, may be falsely attributed to penicillin allergy. Because chronic urticaria is fairly common in the general population, evaluation of its prevalence in patients with self-reported penicillin allergy was of interest. Similarly, the prevalence of self-reported penicillin allergy in patients with chronic urticaria is not well known and also becomes interesting in light of the high prevalence of self-reported penicillin allergy in the general population.

OBJECTIVES

To determine the prevalence of self-reported penicillin allergy in patients with chronic urticaria and the prevalence of chronic urticaria in patients with self-reported penicillin allergy.

METHODS

This was a retrospective medical record review of 11,143 patients completed using the electronic health record of the University of Pennsylvania Allergy and Immunology clinic.

RESULTS

The prevalence of self-reported penicillin allergy in patients with chronic urticaria was found to be approximately 3 times greater than in the general population. The prevalence of chronic urticaria in patients with self-reported penicillin allergy was also found to be approximately 3 times greater than in the population.

CONCLUSION

This link between chronic urticaria and self-reported penicillin allergy highlights the need for clinicians to inquire about self-reported penicillin allergy in patients with chronic urticaria and to consider penicillin skin testing. Furthermore, patients who report penicillin allergy might actually have chronic urticaria, indicating the importance of inquiring about chronic urticaria symptoms in patients with self-reported penicillin allergy.

Immediate-type hypersensitivity drug reactions

Hypersensitivity reactions including anaphylaxis have been reported for nearly all classes of therapeutic reagents and these reactions can occur within minutes to hours of exposure. These reactions are unpredictable, not directly related to dose or the pharmacological action of the drug and have a relatively high mortality risk. This review will focus on the clinical presentation, immune mechanisms, diagnosis and prevention of the most serious form of immediate onset drug hypersensitivity reaction, anaphylaxis. The incidence of drug-induced anaphylaxis deaths appears to be increasing and our understanding of the multiple and complex reasons for the unpredictable nature of anaphylaxis to drugs is also expanding. This review highlights the importance of enhancing our understanding of the biology of the patient (i.e. immune response, genetics) as well as the pharmacology and chemistry of the drug when investigating, diagnosing and treating drug hypersensitivity. Misdiagnosis of drug hypersensitivity leads to substantial patient risk and cost. Although oral provocation is often considered the gold standard of diagnosis, it can pose a potential risk to the patient. There is an urgent need to improve and standardize diagnostic testing and desensitization protocols as other diagnostic tests currently available for assessment of immediate drug allergy are not highly predictive.

Management of allergy to penicillins and other beta-lactams

The Standards of Care Committee of the British Society for Allergy and Clinical Immunology (BSACI) and an expert panel have prepared this guidance for the management of immediate and non-immediate allergic reactions to penicillins and other beta-lactams. The guideline is intended for UK specialists in both adult and paediatric allergy and for other clinicians practising allergy in secondary and tertiary care. The recommendations are evidence based, but where evidence is lacking, the panel reached consensus. During the development of the guideline, all BSACI members were consulted using a Web-based process and all comments carefully considered. Included in the guideline are epidemiology of allergic reactions to beta-lactams, molecular structure, formulations available in the UK and a description of known beta-lactam antigenic determinants. Sections on the value and limitations of clinical history, skin testing and laboratory investigations for both penicillins and cephalosporins are included. Cross-reactivity between penicillins and cephalosporins is discussed in detail. Recommendations on oral provocation and desensitization procedures have been made. Guidance for beta-lactam allergy in children is given in a separate section. An algorithm to help the clinician in the diagnosis of patients with a history of penicillin allergy has also been included.

Beta-Lactam Hypersensitivity and Cross-Reactivity

Penicillin is the most frequently reported cause of drug allergy, and cross-reactivity of penicillins with other beta-lactam antibiotics is an area of debate. This review evaluates the available data on immunoglobulin E-mediated penicillin hypersensitivity and cross-reactivity with cephalosporin, carbapenem, and monobactam antibiotics. A MEDLINE search was conducted from 1950 to October 2013, and selected references from review articles were also evaluated. There is a wide variety in reported incidences of cross-reactivity between penicillins and cephalosporins or carbapenems, with early retrospective studies suggesting up to 41.7% and 47.4% cross-reactivity, respectively. Conversely, the use of monobactam antibiotics is frequently employed in the case of a penicillin allergy, as prescribers believe that there is no cross-reactivity between the 2 drug classes. More recent prospective studies suggest that the rates of cross-reactivity with cephalosporins and carbapenems are <5% and <1%, respectively. Similarities in penicillin and cephalosporin side chains may play a role in cross-reactivity between these classes. Cross-reactivity with monobactams is essentially negligible; however, there are some clinical data to support an interaction between ceftazidime and aztreonam, due to the similarity of their side chains. The data reviewed suggest that avoidance of other beta-lactams in patients with type 1 hypersensitivity to penicillins should be reconsidered.

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.

Penicillin skin testing in cardiac surgery

BACKGROUND

Penicillin is the most commonly reported allergy in cardiac surgical patients and a history of penicillin allergy frequently results in the use of vancomycin for antibiotic prophylaxis. However, clinical history is unreliable and true allergy is rare. Penicillin allergy testing has the potential to reduce vancomycin use and indirectly the potential for selection of vancomycin-resistant organisms, a national priority.

METHODS

After the publication of the 2007 Society of Thoracic Surgeons practice guideline report, we initiated a penicillin allergy testing service for cardiac surgical patients in 2009. We sought to determine the true incidence of penicillin allergy in the tested population, whether testing availability reduced vancomycin use in those tested, and if vancomycin use was reduced in the entire cardiac surgical population as a whole.

RESULTS

A total of 276 patients were skin tested for allergy to penicillin or cephalosporin. Testing recommended no penicillin use in 13.8% of those tested giving a true penicillin allergy incidence of 0.9%. Only 24 of the 276 patients tested (9%) received vancomycin. However, given the small percentage of the total population that underwent allergy testing, the overall use of vancomycin in the cardiac surgery practice was not reduced in the posttesting period.

CONCLUSIONS

The true rate of contraindication to penicillin in a cardiac surgical population is very low. Penicillin allergy testing can reduce vancomycin use in the tested population, but better means of conducting the testing and making the results available are necessary to reduce unnecessary vancomycin use in a broader cardiac surgical population.

Desensitization in patients with beta-lactam drug allergy

BACKGROUND

Patients with a history of beta-lactam antibiotic allergy are often admitted to the hospital with severe or life-threatening infections requiring beta-lactam antibiotics. Strict avoidance of beta lactams to such patients may prevent them from getting adequate coverage and can lead to an increase in the use of alternative antibiotics, which can predispose to antibiotic resistance. Past studies revealed a lower incidence of pen allergy then patients' histories suggest. Fortunately today, there are three options for patients presenting with a history of beta-lactam allergy. Penicillin skin testing, beta-lactam challenge or beta-lactam desensitization. Recently Pre Pen has been FDA re-approved and when combined with Pen G is a valid way to determine if patients are able to tolerate beta-lactam antibiotic. When these agents are not available one must decide about desensitization or challenge. When a patient has a positive penicillin skin test, desensitization or beta-lactam avoidance are the only options. This paper reviews the safety of beta-lactam desensitization.

OBJECTIVE

To perform a chart review on patients desensitised with beta lactam to determine if desensitizations can be performed safely without minimal complications.

METHODS

A retrospective chart review was performed on allergy and immunology inpatient consultations for beta-lactam desensitization between September 2003 and August 2006 at the Cedars-Sinai Medical Centre in Los Angeles. Patient data and outcomes of desensitization were analysed.

RESULTS

A total of 13 intravenous desensitizations were performed on 12 patients. The patients consisted of eight females and four males with an average age of 65 years. Age range was 36-92 years old. All 13 intravenous desensitizations were completed without complications. No patient required a slower rate of desensitization or discontinuance of the desensitization. Patients were able to tolerate the initial therapeutic dose of their beta-lactam antibiotic and were then able to complete full therapeutic courses of their antibiotic.

CONCLUSION

Beta-lactam antibiotic sensitivity continues to present a challenging problem for physicians. Patients with drug resistant infections who are unable to obtain skin testing or who test positive to skin tests may need either a challenge or desensitization. Desensitization, saved for those with a convincing beta-lactam hypersensitivity history is often the choice of last resort given the associated cost and risk of anaphylaxis. However, once desensitization is complete, patients are usually able to tolerate full doses of antibiotics for full treatment length with minimal side effects.

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.

Antibiotic skin testing accompanied by provocative challenges in children is a useful clinical tool

Background

Diagnostic testing to antibiotics other than to penicillin has not been widely available, making the diagnosis of antibiotic allergy difficult and often erroneous. There is often reluctance in performing challenges to antibiotics when standardized testing is lacking. However, while the immunogenic determinants are not known for most antibiotics, a skin reaction at a non-irritating concentration (NIC) may mean that antibodies to the native form are present in the circulation. While the NIC’s for many non penicillin antibiotics have been determined in adults, the use of these concentrations for skin testing pediatric subjects prior to provocative challenge has not been done. Our objective was to determine if we could successfully uncover the true nature of antibiotic allergy in children using these concentrations for testing.

Methods

Children were included between 2003–2009 upon being referred to the Drug and Adverse Reaction/Toxicology (DART) clinic of the Hospital for Sick Children in Toronto, Ontario Canada. The referral needed to demonstrate that clinical care was being compromised by the limitation in antibiotic options or there was a significant medical condition for which the label of antibiotic allergy may prove detrimental. Patients were not seen if there was a suggestion of serum like sickness, Stevens Johnson Syndrome or Toxic Epidermal Necrolysis. Patients were excluded from testing if there was objective evidence of anaphylaxis. All other patients were consented to receive testing and/or challenges. A retrospective chart review was then performed of the results.

Results

We were able to exclude an antibiotic allergy in the majority of our patients who had a negative intradermal test result and were then challenged (>90%). Only one patient was challenged with a positive intradermal test to Cotrimoxazole because of a questionable history and this patient failed the provocative challenge. While we did not challenge more patients with positive testing, we did note that 10/11 (91%) patients with positive intradermal testing had some aspect of a Type 1 reaction in their history.

Conclusions

Through testing with NIC’s of various antibiotics in children and providing provocative challenges based on negative skin testing results, we were able to advance the medical care of the majority of our patients by increasing their antibiotic options in order to successfully treat future infections. While challenging patients with positive testing was not deemed ethically appropriate at this stage of our study, it would be a useful future step to reaching statistical validity of testing to these antibiotics.

Group B Streptococcus prophylaxis in patients who report a penicillin allergy: a follow-up study

OBJECTIVE

The purpose of this study was to compare adherence to the 2002 Centers for Disease Control (CDC) guidelines for the prevention of perinatal group B Streptococcus (GBS) disease in patients who are allergic to penicillin during the years 2004-2006 and 2008.

STUDY DESIGN

Previous data from our institution revealed suboptimal adherence to the 2002 CDC guidelines for GBS prophylaxis among women who are allergic to penicillin. These data caused the hospital to implement a series of interventions. The original cohort (2004-2006) was compared with a cohort of women who delivered between April 2008 and January 2009 (n = 74) to determine whether the proportion of women who had antimicrobial sensitivity testing and who had received an appropriate antibiotic had improved.

RESULTS

In 2008, 76% (95% confidence interval, 66-84%) of GBS-positive women who are allergic to penicillin received an appropriate antibiotic (compared with 16.2% in 2004-2006; P < .001). Antimicrobial sensitivity testing was performed in 79.4% of cases (95% confidence interval, 68-87%), compared with 11.4% in 2004-2006 (P < .001).

CONCLUSION

With directed intervention, adherence to the 2002 CDC guidelines for GBS prophylaxis in women who are allergic to penicillin improved dramatically.

Penicillin skin testing in the evaluation and management of penicillin allergy

OBJECTIVE

to review the role of penicillin skin testing in the evaluation and management of penicillin allergy mediated by IgE.

DATA SOURCES

PubMed and OVID search of English-language articles regarding penicillin allergy, penicillin allergy testing, and management of penicillin allergy.

STUDY SELECTION

articles pertinent to the subject matter were selected and reviewed.

RESULTS

the major determinant (benzylpenicillin polylysine) detects the greatest number of penicillin allergic patients during skin testing, and the minor determinants of penicillin increase the sensitivity of penicillin skin testing. Penicillin skin testing to the major and minor determinants was found to have a negative predictive value of 97% to 99%. The incidence of systemic adverse reaction to penicillin skin testing is less than 1%.

CONCLUSION

a detailed history of the prior reaction to penicillin is an integral part of the evaluation, but it is not accurate in predicting a positive penicillin skin test result. A patient with a negative penicillin skin test result to the major and minor determinants is at a low risk of an immediate-type hypersensitivity reaction to penicillin. Patients with a positive skin test result should undergo desensitization to penicillin or an alternative antibiotic should be considered.

Benzylpenicillin skin testing is still important in diagnosing immediate hypersensitivity reactions to penicillins

BACKGROUND

The fact that both Hollister-Stier and Allergopharma ceased the production of penicilloyl-polylysine (PPL) and minor determinant mixture (MDM) in 2004 is severely hampering the diagnosis of beta-lactam hypersensitivity and may produce negative consequences.

OBJECTIVE

To assess the contribution of skin testing with benzylpenicillin to the diagnosis of immunoglobulin E-mediated hypersensitivity to penicillins, in order to determine how much such testing could compensate for PPL and MDM unavailability.

METHODS

We selected patients with histories of immediate reactions to penicillins and positive results to skin tests for one or more penicillin reagents (PPL, MDM, or benzylpenicillin), one or more semi-synthetic penicillins (ampicillin, amoxicillin, or piperacillin), or both.

RESULTS

A total of 300 patients were selected, 105 in the French center and 195 in the Italian centers. Amoxicillin and ampicillin were the main responsible drugs. The most common clinical manifestation was anaphylaxis. The reagents most frequently positive to skin tests were amoxicillin (188, 62.7%), ampicillin (151, 50.3%), and benzylpenicillin (111, 37.0%). Among the 300 subjects, 113 (37.7%) were positive only to semi-synthetic penicillins, 109 (36.3%) to both semi-synthetic penicillins and the classic penicillin reagents, and 78 (26.0%) only to the latter. In the last group, 64 (21.3% of the 300 subjects) were positive only to PPL and/or MDM and 14 (4.7%) to benzylpenicillin, of whom 8 (2.7%) were positive only to the latter.

CONCLUSIONS

Skin testing with benzylpenicillin can partially compensate for PPL and MDM unavailability. Moreover, it can slightly increase the allergologic workup's sensitivity and therefore reduce the number of potentially dangerous challenges.

Intrapartum group B streptococci prophylaxis in patients reporting a penicillin allergy

OBJECTIVE

To examine adherence to the 2002 Centers for Disease Control and Prevention (CDC) guidelines for group B streptococci (GBS) prophylaxis in patients who reported a penicillin allergy.

METHODS

This is a retrospective cohort study of GBS-positive, penicillin-allergic obstetric patients who delivered at our institution from 2004 through 2005 (N=233). Medical records were analyzed for type of delivery, gestational age at delivery, antimicrobial sensitivity testing, and antibiotics administered. Antimicrobial sensitivity testing and appropriate prophylactic antibiotic choice were analyzed. "Appropriate antibiotic choice" was defined using the 2002 CDC guidelines for GBS prophylaxis. Women with either a scheduled cesarean delivery or a preterm delivery were excluded from analyses. Data were analyzed using Stata 9.0.

RESULTS

Overall, 95% (95% confidence interval [CI] 91-97%) of GBS-positive, penicillin-allergic women received antibiotic prophylaxis and only 16% (95% CI 11-21%) of patients received an appropriate antibiotic. The majority of women who were given antibiotics received clindamycin (83%, 95% CI 77-87%); however, antimicrobial sensitivity testing was performed in only 11% (95% CI 9-17%) of patients. More women received an appropriate antibiotic in 2005 than in 2004 (20% compared with 11%, P=0.11). Although the study was underpowered to evaluate the magnitude of increase, the overall prevalence of appropriate antibiotic administration in 2005 was still only 20% (95% CI 13-28%).

CONCLUSION

Adherence to the 2002 CDC guidelines for GBS prophylaxis in penicillin-allergic women is far from optimal. Improvements are necessary in obtaining antimicrobial sensitivity testing and choosing an appropriate antibiotic for GBS-positive women with a reported penicillin allergy.

LEVEL OF EVIDENCE

II.

Recent advances in the diagnosis of drug allergy

PURPOSE OF REVIEW

The present review addresses the most recent literature regarding the diagnosis of drug hypersensitivity reactions, which can be classified as immediate or nonimmediate according to the time interval between the last drug administration and the onset. Immediate reactions occur within 1 h; nonimmediate ones occur after more than 1 h.

RECENT FINDINGS

Clinical and immunological studies suggest that type-I (IgE-mediated) and type-IV (cell-mediated) pathogenic mechanisms are involved in most immediate and nonimmediate reactions, respectively. New diagnostic tools, such as the basophil activation test and the lymphocyte activation test, have been developed and are under validation.

SUMMARY

In diagnosis, the patient's history is fundamental; the allergologic examination includes in-vivo and in-vitro tests selected on the basis of the clinical features. Prick, patch, and intradermal tests are the most readily available forms of allergy testing. Determination of specific IgE levels is still the most common in-vitro method for diagnosing immediate reactions. The sensitivity of allergologic tests is not 100%; in selected cases, therefore, provocation tests are necessary. The routine use of the basophil activation test and the lymphocyte activation test could increase the sensitivity of diagnostic work-ups, thus reducing the need for drug provocation tests.

Anaphylactic and anaphylactoid causes of angioedema

Anaphylactic and anaphylactoid (pseudoallergic) reactions can be expected to occur with greater frequency as the number of immunomodulators are employed. The immune system will become sensitized to these new therapeutic agents or there may be first-dose reactions depending on the pathogenetic mechanism involved. Physicians should review their office or procedure room emergency preparedness protocols and medications. The lack of penicillin major and minor determinants for penicillin testing has made management of penicillin and cephalosporin allergic patients more complicated. In the absence of skin-testing materials, test-challenges will be necessary and performed with less comfort because of not knowing the current level of immunologic sensitization to penicillin. The indication for readministration of any incriminated medication/therapeutic agent should be reviewed. Often, there are not suitable alternatives. Various approaches have been presented to permit safer readministration of essential medications or diagnostic agents to prevent episodes of anaphylaxis or upper airway angioedema.