Skin testing to detect penicillin allergy

Penicillin Allergy: Mechanisms, Diagnosis, and Management

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

Impact of antimicrobial stewardship interventions on peripartum antibiotic prescribing in patients with penicillin allergy

BACKGROUND

Beta-lactam antibiotics (eg, penicillins, cephalosporins, and carbapenems) are preferred for group B streptococcus prophylaxis, intra-amniotic infection, and cesarean surgical site infection prophylaxis. Non-beta-lactam alternatives are associated with inferior efficacy and contribute to higher rates of surgical site infection and longer lengths of stay. Most patients who report a penicillin allergy can tolerate penicillins without any adverse reaction. There are low rates of cross-reactivity between penicillins and other beta-lactams, including cephalosporins and carbapenems. Efforts to evaluate penicillin allergy and promote the use of beta-lactams are needed.

OBJECTIVE

This study aimed to evaluate whether an antimicrobial stewardship intervention improved the use of first-line antibiotics for peripartum indications in patients with a reported penicillin allergy, following updates to institutional guidelines.

STUDY DESIGN

This was a retrospective study of adult patients presenting for vaginal or cesarean delivery at 2 hospitals within a healthcare system. Patients received at least 1 dose of antibiotics for a peripartum indication between May 1, 2018, and October 31, 2018 (preintervention group) and May 1, 2020, to October 31, 2020 (postintervention group). The stewardship intervention bundle, which was implemented between March 2019 and April 2020, included updates to institutional antibiotic guidelines, reclassification of severe penicillin allergy, development of obstetrical prophylaxis and treatment order sets, promotion of allergy referral services, and establishment of a physician champion. The primary outcome was the composite rates of patients with reported penicillin allergy who received a preferred antibiotic for a peripartum indication. The secondary measures included maternal and neonatal outcomes.

RESULTS

A total of 192 patients with a history of documented penicillin allergy were evaluated (96 patients in the preintervention group and 96 patients in the postintervention group). Hives were the most commonly reported index symptom in both groups (40/96 [41.7%] vs 39/96 [40.6%]; P=.883). After stewardship interventions, there was a significant increase in the rate of preferred antibiotic use (33/96 [34.3%] vs 81/96 [84.3%]; P<.001). The effect was the greatest in patients with nonsevere allergy (14/76 [18.4%] vs 68/82 [82.9%]; P<.001). There was no difference in the rates of postpartum endometritis, 30-day readmission, 90-day surgical site infection, or neonatal early-onset sepsis between the pre- and postintervention groups. Of note, 1 patient in the postintervention group experienced itching, and another patient developed a rash, both of which resolved with medical management.

CONCLUSION

A comprehensive antibiotic stewardship intervention was associated with a 50% increase in the use of preferred antibiotics for peripartum indications in patients with penicillin allergy. Allergic reactions with first-line beta-lactams were minimal and manageable.

Penicillin allergy delabeling: Opportunities for implementation and dissemination

Although existing as a safety measure to prevent iatrogenic harm, unconfirmed penicillin allergy labels have a negative impact on personal and public health. One downstream effect of unconfirmed penicillin allergy is the continued emergence and transmission of resistant bacteria and their associated health care costs. Recognizing the consequences of inaccurate penicillin allergy labels, professional and public health organizations have started promoting the adoption of proactive penicillin allergy evaluations, with the ultimate goal of removing the penicillin allergy label when the allergy is disproved, also known as penicillin allergy "delabeling." A penicillin allergy evaluation includes a comprehensive allergy history often followed by drug challenge, sometimes with preceding skin testing. Currently, penicillin allergy delabeling is largely carried out by allergy specialists in outpatient settings. Penicillin allergy delabeling is performed on inpatients, albeit rarely, often at the time of need, as a point-of-care procedure. Access to penicillin allergy evaluation services is limited. Recent studies demonstrate the feasibility of expanding penicillin allergy evaluations and delabeling to internists, pediatricians, emergency medicine physicians, infectious diseases specialists, and clinical pharmacists. However, reducing the impact of mislabeled penicillin allergy will require comprehensive efforts and new investments. In this review, we summarize the current practices of penicillin allergy delabeling and discuss expansion opportunities for penicillin allergy delabeling as quality improvement.

The Evolution of Our Understanding of Penicillin Allergy: 1942-2022

This article reviews our evolving understanding of penicillin hypersensitivity at the 80th anniversary of penicillin's clinical introduction. Penicillin breakdown products covalently bond to serum proteins, leading to classic drug hypersensitivity. Penicillin remains the most frequently reported drug "allergy." Adverse reactions were presumed, in retrospect incorrectly, to implicate a risk for anaphylaxis, and therefore skin testing for IgE became the focus. Skin test positivity may wane over time. This insight has led to the radical conclusion that penicillin hypersensitivity may not be "forever." Atopic background, other drug allergies, family history, gender, and race are apparently not risk factors for penicillin hypersensitivity. Confirmed penicillin hypersensitivity has declined since the 1960s, potentially due to "cleaner" penicillin products and lower dose oral, instead of parenteral, use. Avoiding penicillins, without evaluation, caused unanticipated problems that have been appreciated only recently including longer hospital stays, increased cost of care, suboptimal outcomes from serious infections, and greater toxicities and costs with alternative antibiotics. There are personal and public health advantages with broadly implemented penicillin allergy delabeling based on a reaction history-based risk assessment. Limited skin testing followed by an oral challenge, if negative, for higher-risk histories, and direct oral challenges in lower-risk individuals are currently the reference standard tests to confirm current tolerance.

Penicillin Allergy

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

A case of persistent IgE sensitisation almost two decades following ampicillin anaphylaxis

BACKGROUND

Although most immunoglobulin E (IgE)-mediated penicillin allergy wanes with time, sensitisation may occasionally persist for many years. Previous reports on the loss of penicillin-specific IgE sensitisation were based on non-anaphylaxis cases and, although uncommon, persistent sensitisation may still be possible in the minority of cases.

OBJECTIVE

This case highlights that irrespective of the elapsed duration since the index reaction, it is important to remain vigilant when approaching patients with a history of severe reactions.

MATERIAL AND METHODS

We described a case of persistent IgE sensitisation almost two decades following ampicillin anaphylaxis.

RESULTS

A 78-year-old male with a history of perioperative penicillin anaphylaxis in 2003 was referred for allergy workup in 2022 before his knee joint replacement surgery. The patient had strictly avoided all beta-lactams since the index reaction. However, his penicillin-specific sensitisation persisted, evidenced by positive skin tests (with generalised urticaria after intradermal testing) and basophil activation tests.

CONCLUSION

To our knowledge, this was the first case of positive BAT tested around two decades following the index reaction. This case illustrates that a cautious approach may still be warranted in patients with a history of severe reaction to penicillin regardless of the duration since the reported index reaction.

Management of Beta-Lactam Antibiotics Allergy: A Real-Life Study

Beta-lactam allergy is a common problem in everyday medical practice and is recognized as a major public health issue. Carrying this label frequently leads to the avoidance of all beta-lactam antibiotics, favoring the use of other less preferred classes of antibiotics, that are more expensive and associated with more side effects and increased antimicrobial resistance. Therefore, delabeling a beta-lactam allergy is part of antimicrobial stewardship programs. Herein, we retrospectively examined the clinical records of 576 patients who were referred to our center for a label of allergy to beta-lactam antibiotics and were systematically investigated following a standardized algorithm. Our main aim was to evaluate the frequency of confirmed immediate- and delayed-type allergy to commonly prescribed subclasses of beta-lactam antibiotics (penicillin and cephalosporin), as well as the negative predictive value (NPV) and the sensitivity of skin tests. Our secondary aims were to examine the safety of beta-lactam skin testing and drug challenge. We identified that 260 patients reported a history of immediate reactions, 131 of delayed reactions, and 114 of unknown timing or mechanism of reactions. Following assessment and testing, 86 (18.3%) patients had a confirmed allergy to any beta-lactam antibiotics; 63 (13.4%) with an immediate- and 23 (4.9%) with a delayed-type reaction. Most frequently identified confirmed allergy was to penicillins (65 patients), followed by cephalosporins (21 patients). When immediate-type reactions were examined, NPV of skin tests were 96.3% and 100% for penicillins and cephalosporins, respectively. When delayed reactions were considered, NPV were 91.9 and 87.5% for penicillins and cephalosporins, respectively. Evaluation of the safety of skin tests according to the standardized procedure showed that systemic allergic reactions occurred in only 0.7% of skin tests and in 3.1% of drug challenges. Overall, our data indicate that only 18.3% of patients with a beta-lactam allergy label have a confirmed allergy and non-allergic patients can be safely delabeled through allergic workup based on skin tests and drug challenge. This approach supports the policy of saving second-line antibiotics through a standardized allergy workup.

Direct Challenges for the Evaluation of Beta-Lactam Allergy: Evidence and Conditions for Not Performing Skin Testing

In the western world, up to 10% of the general population and more than 15% of hospitalized patients report penicillin allergy. After a comprehensive evaluation, more than 95% of patients who report a penicillin allergy can subsequently tolerate this antibiotic. Traditionally, the most widely accepted protocol to evaluate beta-lactam (BL) allergy consisted of skin testing (ST) followed by a drug provocation test (DPT) in ST-negative patients. DPT is the gold standard for proving or excluding BL allergy and is considered the final and definitive step in the evaluation. Recently, studies have been published that support the use of direct DPTs without preceding ST for both pediatric and adult patients who report a low-risk historical reaction to BLs. However, these studies use various risk-stratification criteria to determine eligibility for a direct DPT. A standardized protocol for DPT is also lacking. In this review, we assess the current literature and evidence for performing direct DPT in the pediatric and adult populations. On the basis of this evidence, we also present risk-based algorithms for the evaluation of BL allergy in pediatric and adult populations based on a description of the historical reaction.

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.

Taking a Rational Approach to a Reported Antibiotic Allergy

Up to 10% of hospitalized patients have an antibiotic allergy label in their medical file, most frequently concerning penicillins. However, the vast majority of reported allergies to antibiotics does not represent a "true" allergy but are due to drug intolerance, idiosyncratic reactions or symptoms of the concurrent infectious disease. Since antibiotic allergy labels result in deviation from first-choice antimicrobial therapy, tackling the issue of incorrect antibiotic allergy labelling, already at young age, is a core element of antibiotic stewardship. In this article, we describe the structured approach to the patient with a presumed antibiotic allergy with emphasis on key elements of allergy-specific history taking and the limited risk of cross-allergic reactions between beta-lactam subclasses.

Skin Testing for Penicillin Allergy: a Review of the Literature

PURPOSE OF REVIEW

Self-reported penicillin allergies are frequently reported, though more than 95% of those are not truly allergic when challenged. These patients are more likely to receive alternative antibiotic regimens resulting in the use of broad-spectrum antibiotics that may be less effective, more toxic, and/or more expensive than preferred agents. Given the significant burden on patient outcomes and the healthcare system, the ability to reconcile an allergy and broaden future antibiotic options is essential.

RECENT FINDINGS

This is a narrative review describing risk stratification for penicillin skin testing, practical advice for implementation, and future directions. A summary of studies within the last 5 years is provided. The trend over the past several years has been to offer oral drug challenges to low-risk patients and skin testing to high-risk patients with a reported penicillin allergy. This review provides support for risk stratification assessment of reported penicillin allergy to optimize antibiotic use and prevent emergence of antimicrobial resistance.

Practical guide for evaluation and management of beta-lactam allergy: position statement from the Canadian Society of Allergy and Clinical Immunology

The vast majority of individuals labelled as allergic are not deemed truly allergic upon appropriate assessment by an allergist. A label of beta-lactam allergy carries important risks for individual and public health. This article provides an overview of beta-lactam allergy, implications of erroneous beta-lactam allergy labels and the impact that can be provided by structured allergy assessment. We provide recommendations on how to stratify risk of beta-lactam allergy, beta lactam challenge protocols as well as management of patients at high risk of beta-lactam allergy.

Characterization of amoxicillin and clavulanic acid specific T-cell clones from patients with immediate drug hypersensitivity

BACKGROUND

Betalactam (BL) antibiotics are the most common cause of drug hypersensitivity. Amoxicillin (AX), which is often prescribed alongside clavulanic acid (Clav), is the most common elicitor. The aim of this study was to determine whether AX and Clav-responsive T-cells are detectable in patients with immediate hypersensitivity to AX-Clav, to assess whether these T-cells display the same specificity as that detected in skin and provocation testing, and to explore T-cell activation pathways.

METHODS

Drug-specific T-cell clones were generated from immediate hypersensitive patients´ blood by serial dilution and repetitive mitogen stimulation. Antigen specificity was assessed by measurement of proliferation and cytokine release. CD4+ /CD8+ phenotype and chemokine receptor expression were analyzed by flow cytometry.

RESULTS

110 AX-specific and 96 Clav-specific T-cell clones were generated from seven patients with positive skin test to either AX or Clav. Proliferation of AX- and Clav-specific clones was dose-dependent, and no cross-reactivity was observed. AX- and Clav-specific clones required antigen-presenting cells to proliferate, and drugs were presented to CD4+ and CD8+ T-cells by MHC class-II and I, respectively. A higher secretion of IL-13 and IL-5 was detected in presence of the culprit drug compared with the alternative drug. Clones expressed CD69, CCR4, CXCR3, and CCR10.

CONCLUSIONS

Our study details the antigen specificity and phenotype of T-cell clones generated from patients with AX-Clav-induced immediate hypersensitivity diagnosed by positive skin test. AX- and Clav-specific clones were generated from patients irrespective of whether AX or Clav was the culprit, although differences in cytokine secretion were observed.

Microchip capillary electrophoresis dairy device using fluorescence spectroscopy for detection of ciprofloxacin in milk samples

Detecting antibiotics in the milk supply chain is crucial to protect humans from allergic reactions, as well as preventing the build-up of antibiotic resistance. The dairy industry has controls in place at processing facilities, but controls on dairy farms are limited to manual devices. Errors in the use of these manual devices can result in severe financial harm to the farms. This illustrates an urgent need for automated methods of detecting antibiotics on a dairy farm, to prevent the shipment of milk containing antibiotics. This work introduces the microchip capillary electrophoresis dairy device, a low-cost system that utilizes microchip capillary electrophoresis as well as fluorescence spectroscopy for the detection of ciprofloxacin contained in milk. The microchip capillary electrophoresis dairy device is operated under antibiotic-absent conditions, with ciprofloxacin not present in a milk sample, and antibiotic-present conditions, with ciprofloxacin present in a milk sample. The response curve for the microchip capillary electrophoresis dairy device is found through experimental operation with varied concentrations of ciprofloxacin. The sensitivity and limit of detection are quantified for the microchip capillary electrophoresis dairy device.

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.

Minor Determinants of Penicillin and Amoxicillin Are Still Key Components of Penicillin Skin Testing

BACKGROUND

The positive rate and pattern of penicillin skin test (PST) has been reported to be decreasing and changing. Previous studies differ about which penicillin component is the dominant component in positive PST result.

OBJECTIVE

To characterize past and current PST patterns to determine whether different determinants in PST have changed over time.

METHODS

A retrospective review of electronic medical records (January 2001-December 2017) was performed for patients who underwent PST. Data were divided into 4 cohorts to see whether trends occurred over time. The cohorts were divided as follows: cohort 1 (2001-2005), cohort 2 (2006-2010), cohort 3 (2011-2015), and cohort 4 (2016-2017).

RESULTS

A total of 30,883 patients underwent PST with the following breakdowns per cohort: cohort 1, 6,536; cohort 2, 10,372; cohort 3, 10,640; and cohort 4, 3,335. Of these, 329 patients (1.0%) had a positive PST result with a wheal of 3 × 3 mm or greater, with 110 in cohort 1, 130 in cohort 2, 67 in cohort 3, and 22 in cohort 4, whereas 170 patients (0.5%) had a positive PST result with a wheal of 5 × 5 mm or greater, with 54 in cohort 1, 72 in cohort 2, 34 in cohort 3, and 10 in cohort 4. When the positive PST rates of cohort 2 (1.25%), cohort 3 (0.6%), and cohort 4 (0.6%) were compared with those of cohort 1 (1.7%), there was a significant decrease in positive PST rates (P = .0278; P < .0001; P < .0001, respectively). When cohort 1 positive rate to benzylpenicillin polylysine among the positive PST (wheal of 3 × 3 mm or greater) was compared with those of the other cohorts (cohorts 2-4), the percent positive of benzylpenicillin polylysine in PST was 27% compared with 21% (P = .38), 34% (P = .5), and 18% (P = .6), respectively. When the positive PST result was defined as a wheal of 5 × 5 mm or greater, the positive rate for benzylpenicillin polylysine in PST increased over time (cohort 2: 22%, P = .8; cohort 3: 32%, P = .3; cohort 4: 40%, P = .264) compared with cohort 1 (19%).

CONCLUSIONS

Positive PST rate is decreasing. We demonstrate that despite benzylpenicillin polylysine solely positive rates remaining relatively stable, the minor penicillin determinants and amoxicillin play an important role in PST and their adoption into standard protocol for routine PST should be considered.

Impact of β-Lactam Allergies on Antimicrobial Selection in an Outpatient Setting

OBJECTIVE

The primary objective of this study was to determine whether patients prescribed nonpreferred antibiotics received appropriate alternative antibiotics.

METHODS

This was a retrospective observational analysis of military veteran patients with a β-lactam allergy treated in an outpatient clinic or emergency department for an infection during a 5-year span. Antibiotic regimens were first stratified as preferred or nonpreferred based on infection-specific guidelines. The nonpreferred regimens were then evaluated for appropriateness based on allergy history and culture and sensitivity reports.

RESULTS

Of 445 fills of antibiotics evaluated, 269 met inclusion criteria, comprising 253 unique infections in 80 patients. Patients received nonpreferred antibiotics for their infection type in 57% of cases. Of the nonpreferred antibiotics, 56% were inappropriate based on guideline-recommended alternatives, allergy history, and culture and sensitivity data. Of the 88 allergies, 97% were historical/self-reported and 48% were cutaneous. In addition, 39% of patients safely received β-lactam antibiotics after documentation of their allergy.

CONCLUSIONS

Patients with documented β-lactam allergies are at high risk of receiving nonpreferred and inappropriate antibiotics, and many reactions likely do not reflect true allergies. These data emphasize the negative impact of the "β-lactam allergy" label and the importance of reassessing allergies.

Antimicrobial stewardship intervention: optimizing antibiotic treatment in hospitalized patients with reported antibiotic allergy

BACKGROUND

Reported antibiotic allergy in hospitalized patients seems to be related to more adverse events, the use of reserve antibiotics and longer hospitalization. Most patients reporting an antibiotic allergy can be de-labelled; as such, an antimicrobial stewardship intervention was set up.

AIM

To determine the impact of reported antibiotic allergy on the antibiotic treatment of hospitalized patients, and prevent unnecessary deviation from the preferred antibiotic treatment by a proactive antimicrobial stewardship intervention.

METHODS

Hospitalized patients reporting an antibiotic allergy were included in an intervention study at a teaching hospital in the Netherlands between March and May 2019. Physicians received training and were provided with a recommendation in the electronic medical record in case the preferred antibiotic treatment was unnecessarily avoided due to the allergy label and the patient was eligible for a drug challenge.

FINDINGS

In total, 492 patients reporting an antibiotic allergy were identified, accounting for 558 hospital admissions. In 93 cases, the antibiotic allergy label interfered with the preferred antibiotic treatment. Sixty-eight of these patients were eligible for a drug challenge, and 42 patients were challenged. In 40 (95%) of these patients, no allergic reaction was observed, and the preferred antibiotic treatment was given. Two (5%) patients developed a non-severe skin reaction after a drug challenge and continued an alternative antibiotic regimen.

CONCLUSION

This antimicrobial stewardship intervention can be used to provide patients with reported antibiotic allergy labels with the preferred antibiotic treatment, and to de-label them after uneventful re-exposure to the antibiotic agent.

Discrepancies Between Patient Self-Reported and Electronic Health Record Documentation of Medication Allergies and Adverse Reactions in the Acute Care Setting: Room for Improvement

Background: Allergy information is commonly transcribed into an electronic health record (EHR) for all patients admitted to acute care hospital units by a licensed health care professional. The allergy history is utilized each time a new inpatient medication is prescribed to identify the patient's risk of having an allergic reaction and/or anaphylaxis. There is potential for negative consequences in cases where the allergy history is incorrectly documented. Objective: The objective of this study was to assess the discordance between documented allergy information in the EHR and verbally reported allergy information from a patient interview. Methods: Prospective, observational, nonrandomized study performed within a 2-month period during the Spring of 2016. The study was performed at a teaching community hospital in Chicago, Illinois. A total of 270 patients were interviewed on the general medicine (n = 216) and headache (n = 54) units regarding their medication allergies and reactions. The outcomes were discordance among EHR-documented and verbally stated medication allergies and reactions. Results: The agreement across all medications and reactions between the EHR and patient self-reported interview was 80.9%. There were 31 reactions (6.7%) that were verbally reported by patients but were not documented in the EHR (omissions) and 57 reactions (12.4%) that were verbally reported but were incorrectly documented in the EHR (incorrect documentations). Only 20 out of the 264 verbally reported reactions (7.5%) met the study definition of anaphylaxis. The highest rate of incorrect documentations occurred with opiate agonists, and the highest rate of omissions occurred with anticonvulsants. EHR documentation was more likely to be incorrect among patients who reported gastrointestinal reactions and was more likely to be correct among patients who reported cutaneous reactions. Conclusion: There was a high rate of discordance amid EHR-documented and verbally stated medication allergies and reactions. Errors among opiate agonists, anticonvulsants, and sulfa drugs were most prevalent.

β-Lactam vs Non-β-Lactam Antibiotics and Surgical Site Infection in Colectomy Patients

BACKGROUND

Surgical site infections (SSIs) represent a significant preventable source of morbidity, mortality, and cost. Prophylactic antibiotics have been shown to decrease SSI rates, and β-lactam antibiotics are recommended by national guidelines. It is currently unclear whether recommended β-lactam and recommended non-β-lactam antibiotic regimens are equivalent with respect to SSI risk reduction in colectomy patients.

STUDY DESIGN

We conducted a retrospective cohort study of SSI rates between prophylactic intravenously administered recommended β-lactam and non-β-lactam in colectomy patients (25 CPT codes) collected by the Michigan Surgical Quality Collaborative from January 2013 to February 2018. Surgical site infection rates were compared as a dichotomous variable (no SSI vs SSI). Mixed-effects regression was used to compare the association between receiving a β-lactam or non-β-lactam antibiotic and likelihood of having an SSI.

RESULTS

Of 9,949 patients, 9,411 (94.6%) received β-lactam antibiotics and 538 (5.4%) received non-β-lactam antibiotics. Overall, there were 622 (6.3%) patients with SSIs. Of the patients receiving β-lactam antibiotics, SSIs developed in 571 (6.1%) compared with 51 (9.5%) patients in the non-β-lactam group. After applying mixed-effects logistic regression, prophylactic treatment with a non-β-lactam regimen was associated with significantly higher odds of surgical site infection (odds ratio 1.65; 95% CI 1.20 to 2.26; p < 0.01).

CONCLUSIONS

Colectomy patients receiving β-lactam antibiotics had a lower likelihood of SSI compared with those receiving non-β-lactam antibiotics, even when antibiotics were compliant with national recommendations. Our findings suggest that surgeons should prescribe β-lactam antibiotics for prophylaxis whenever possible, reserving alternatives for those rare patients with true allergies or clinical indications for non-β-lactam antibiotic prophylaxis.

Penicillin Allergy Evaluation: A Prospective, Multicenter, Open-Label Evaluation of a Comprehensive Penicillin Skin Test Kit

BACKGROUND

Ten percent of the population claims an allergy to penicillin, but 90% of these individuals are not allergic. Patients labeled as penicillin-allergic have higher medical costs, longer hospital stays, are more likely to be treated with broad-spectrum antibiotics, and develop drug-resistant bacterial infections. Most penicillin skin test reagents are not approved by the Food and drug Administration or readily available to evaluate patients labeled penicillin-allergic.

OBJECTIVE

To determine the negative predictive value (NPV) of the Penicillin Skin Test Kit containing the major allergenic determinant (penicilloyl polylysine), a minor determinant mixture (penicillin G, penicilloate, penilloate), and amoxicillin, produced according to Food and Drug Administration standards.

METHODS

This was a prospective, multicenter, open-label investigation of penicillin skin testing using the Penicillin Skin Test Kit. Skin test-negative subjects were challenged with 250 mg amoxicillin, whereas skin test-positive patients were not challenged. The primary end point was NPV of the Penicillin Skin Test Kit, defined as the percentage of subjects with negative skin test results who did not experience an IgE-dependent reaction within 72 hours of amoxicillin challenge.

RESULTS

In total, 455 patients with a history of penicillin allergy underwent skin testing and 63 (13.8%) had 1 or more positive test results; 65% of the positive test results were to the minor determinant mixture and/or amoxicillin alone. In the per protocol group of 373 skin test-negative subjects, 8 developed potential IgE-dependent reactions following oral amoxicillin challenge, translating to an NPV of 97.9% (95% CI, 95.8-99.1; P < .0001). All but 1 of the reactions was mild or moderate, and most subjects who required treatment received only antihistamines.

CONCLUSIONS

The Penicillin Skin Test Kit, containing all relevant penicillin allergenic determinants, demonstrated very high NPV. Removal of a penicillin allergy label in a large majority of currently mislabeled patients has substantial personal and public health implications.

Penicillin minor determinants: History and relevance for current diagnosis

OBJECTIVE

To review the history of the penicillin minor determinants and evaluate their relevance for current diagnosis.

DATA SOURCES

Skin testing to detect immunoglobulin E (IgE) sensitivity to penicillins in patients with a history of penicillin allergy has been the subject of more than 55 years of published research involving tens of thousands of patients.

STUDY SELECTIONS

Selection of data was based on its relevance to the objective of this article.

RESULTS

It was established early on that testing with the major penicilloyl determinant using the polyvalent penicilloyl-polylysine (PPL) is negative in a substantial portion (10% to 64%, including recent increases) of those at risk for immediate hypersensitivity reactions. A variety of minor penicillin determinants are clinically significant in that their use in skin testing is essential to detect all those at risk. In particular, a minor determinant mixture of benzylpenicillin, benzylpenicilloate, and benzylpenilloate, used in conjunction with PPL, has been shown in numerous studies to achieve an average negative predictive value (NPV) of 97.9% in history-positive patients. Benzylpenicillin alone, as the sole minor determinant, leaves many skin test-positive patients undiscovered. Use of amoxicillin as an additional minor determinant reagent appears to identify another 2% to 8% of skin test-positive patients in some populations.

CONCLUSION

IgE skin testing, using both the major and appropriate minor determinants of penicillin, can identify, with a high degree of reliability (NPV ∼97%), penicillin allergy history-positive patients who can receive beta-lactam antibiotics without concern for serious acute allergy, including anaphylaxis. The few false-negative skin tests reported globally are largely confined to minor, self-limited cutaneous reactions.

Improving Aztreonam Stewardship and Cost Through a Penicillin Allergy Testing Clinical Guideline

Background

Patients reporting penicillin allergy often receive unnecessary and costly broad-spectrum alternatives such as aztreonam with negative consequences. Penicillin allergy testing improves antimicrobial therapy but is not broadly used in hospitals due to insufficient testing resources and short-term expenses. We describe a clinical decision support (CDS) tool promoting pharmacist-administered penicillin allergy testing in patients receiving aztreonam and its benefits toward antimicrobial stewardship and costs.

Methods

A CDS tool was incorporated into the electronic medical record, directing providers to order penicillin allergy testing for patients receiving aztreonam. An allergy-trained pharmacist reviewed orders placed through this new guideline and performed skin testing and oral challenges to determine whether these patients could safely take penicillin. Data on tests performed, antibiotic utilization, and cost-savings were compared with patients tested outside the new guideline as part of our institution's standard stewardship program.

Results

The guideline significantly increased penicillin allergy testing among patients receiving aztreonam from 24% to 85% (P < .001) while reducing the median delay between admission and testing completion from 3.31 to 1.05 days (P = 0.008). Patients tested under the guideline saw a 58% increase in penicillin exposure (P = .046). Institutional aztreonam administration declined from 2.54 to 1.47 administrations per 1000 patient-days (P = .016). Average antibiotic costs per patient tested before and after CDS decreased from $1265.81 to $592.08 USD, a 53% savings.

Conclusions

Targeting penicillin allergy testing to patients on aztreonam yields therapeutic and economic benefits during a single admission. This provides a cost-effective model for inpatient testing.

Systematic review of professional liability when prescribing β-lactams for patients with a known penicillin allergy

OBJECTIVE

To describe medical negligence and malpractice cases in which a patient with a known penicillin allergy received a β-lactam and experienced an adverse reaction related to the β-lactam.

DATA SOURCES

Lexis-Nexus, Westlaw, and Google Scholar were searched.

STUDY SELECTIONS

Medical negligence and malpractice cases were eligible for inclusion if they met the following criteria: the plaintiff had a known penicillin allergy, received a β-lactam, and experienced an adverse event. All United States federal and state cases were eligible.

RESULTS

Twenty-seven unique cases met the inclusion criteria. Eighteen cases involved the receipt of a penicillin-based antibiotic; of these cases with a known legal outcome, the plaintiff (patient or representative) prevailed or settled in 3 cases and defendants (providers) prevailed in 7 cases. Seven cases involved the receipt of a cephalosporin; of these cases with a known legal outcome, the plaintiff settled with physicians before trial in 1 case and defendants prevailed in 3 cases. Two cases involved the receipt of a carbapenem. Defendants prevailed in one case and the legal outcome of the other case is unknown. In cases in which the defense successfully moved for summary judgment, judges cited a lack of scientific evidence demonstrating a cephalosporin or carbapenem was contraindicated for a patient with a penicillin allergy.

CONCLUSION

The cases with published legal outcomes found limited professional liability for clinicians who prescribed cephalosporins or carbapenems to a patient with a known penicillin allergy. These results may decrease the litigation fears of practitioners and risk managers within health care systems.

Evaluation of Penicillin Allergy in the Hospitalized Patient: Opportunities for Antimicrobial Stewardship

PURPOSE OF REVIEW

Penicillin allergy is often misdiagnosed and is associated with adverse consequences, but testing is infrequently done in the hospital setting. This article reviews historical and contemporary innovations in inpatient penicillin allergy testing and its impact on antimicrobial stewardship.

RECENT FINDINGS

Adoption of the electronic medical record allows rapid identification of admitted patients carrying a penicillin allergy diagnosis. Collaboration with clinical pharmacists and the development of computerized clinical guidelines facilitates increased testing and appropriate use of penicillin and related β-lactams. Education of patients and their outpatient providers is the key to retaining the benefits of penicillin allergy de-labeling. Penicillin allergy testing is feasible in the hospital and offers tangible benefits towards antimicrobial stewardship. Allergists should take the lead in this endeavor and work towards overcoming personnel limitations by partnering with other health care providers and incorporating technology that improves the efficiency of allergy evaluation.

Penicillin and Beta-Lactam Hypersensitivity

Ten percent of patients report penicillin allergy, but more than 90% of these individuals can tolerate penicillins. Skin testing remains the optimal method for evaluation of possible IgE-mediated penicillin allergy and is recommended by professional societies, as the harms for alternative antibiotics include antimicrobial resistance, prolonged hospitalizations, readmissions, and increased costs. Removal of penicillin allergy leads to decreased utilization of broad-spectrum antibiotics, such as fluoroquinolones and vancomycin. There is minimal allergic cross-reactivity between penicillins and cephalosporins. IgE-mediated allergy to cephalosporins is usually side-chain specific and may warrant graded challenge with cephalosporins containing dissimilar R1 or R2 group side chains.

Risk of Allergic Reactions to Recurrent Intravenous Penicillin Administration in Penicillin Skin Test Negative Patients

BACKGROUND

Patients with a history of penicillin allergy who are found to be skin test negative to penicillin are able to tolerate repeated oral doses of penicillin with low rates of resensitization. However, the resensitization rate after repeated doses of intravenous penicillin is less clear.

OBJECTIVE

We sought to evaluate the risk of allergic reactions to repeated doses of intravenous penicillin in patients who previously reported penicillin allergy and were found to be penicillin skin test and oral challenge negative.

METHODS

A retrospective review was conducted between 2010 and 2016 of adult patients who were treated at our academically affiliated hospitals. Patients included in the review had negative penicillin allergy testing and were treated with 2 or more courses of intravenous penicillins. Charts were evaluated to identify any adverse drug reactions.

RESULTS

Thirty-two patients met our inclusion criteria. The index penicillin-associated reactions ranged from rash to hypotension and were, for the most part, remote as 75% had reported reactions more than 10 years previously. More than 50% of patients received 3 or more courses of intravenous penicillins. The most frequently repeated intravenous penicillin overall was piperacillin/tazobactam. Thirty-two patients received a total of 111 courses of intravenous penicillins and none developed an immediate hypersensitivity reaction.

CONCLUSIONS

In patients who report penicillin allergy and have negative penicillin allergy testing, repeated administration of intravenous penicillin antibiotics appears to be safe. Larger prospective studies should be performed to confirm these observations.

Epidemiology of anaphylaxis at a tertiary care center: A report of 730 cases

BACKGROUND

Recent data reveal that the rate of anaphylaxis is increasing and suggest that idiopathic anaphylaxis may account for most of these cases.

OBJECTIVE

To determine the pattern of anaphylaxis at a tertiary care referral center.

METHODS

A retrospective electronic medical record review spanning 12 years (2002-2013) identified patients with anaphylaxis.

RESULTS

Of the 4,777 records reviewed, 730 patients met our anaphylaxis definition. Median age was 34.0 years; 72.7% were adults, 58.6% were female, and 86.8% were white. Median time to evaluation by an allergist was 8.8 months. Foods were the most common cause (29.9%), followed by Hymenoptera venom (24.6%), idiopathic anaphylaxis (13.7%), and medications (13.3%). The most common foods were peanuts (23.9%), tree nuts (21.6%), shellfish (16.1%), and egg and milk (both 10.1%). The most common cause of anaphylaxis in adults was Hymenoptera venom. The most frequent symptoms were urticaria and/or angioedema, reported in 84.7% of cases. Atopy was present in 43.8%. In 15.4% of cases, anaphylaxis was not the chief reason for the office visit.

CONCLUSION

We found food allergy was the most common overall cause of anaphylaxis, with peanut the most frequent food trigger. Idiopathic anaphylaxis was not the most common cause but accounted for 13.7% of all cases. Approximately 1 in 6 cases of anaphylaxis may be missed if a comprehensive evaluation is not performed.

Allergy test outcomes in patients self-reported as having penicillin allergy: Two-year experience

BACKGROUND

Penicillin allergy is associated with increased antibiotic resistance and health care costs. However, most patients with self-reported penicillin allergy are not truly allergic.

OBJECTIVE

To summarize our experience with allergy tests in patients with a history of penicillin allergy and to compare them with the results of other groups.

METHODS

We retrospectively reviewed all patients with a suspected clinical history of penicillin allergy referred to the Drug Allergy Unit at University College London Hospital between March 2013 and June 2015.

RESULTS

In total, 84 patients were reviewed. The index drugs included: unidentified penicillin (n = 44), amoxicillin (n = 17), amoxicillin-clavulanic acid (n = 13), flucloxacillin (n = 4), and other penicillins (ampicillin, benzylpenicillin, piperacillin-tazobactam; n = 7). Allergy diagnoses were confirmed in 24 patients (28.6%) (16 to penicillin, 3 to flucloxacillin, 5 to clavulanic acid). Twenty-two patients (91.7%) had allergy diagnosed by positive skin test results. Two patients (8.3%) developed IgE-mediated allergic symptoms during oral challenge (although the skin test results were negative). In vitro specific IgE test results for penicilloyl V, penicilloyl G, and amoxicilloyl were positive in 3 of 16 patients (18.8%). Moreover, reactions to cefuroxime were observed in 3 of 15 patients with penicillin allergy (20%). Selective clavulanic acid and flucloxacillin responders tolerated amoxicillin challenge. The interval between the index reaction and evaluation was shorter (P < .001), and the proportion of patients who could recall the name of the culprit drug was higher (P = .009) in the allergic group. Furthermore, histories of anaphylaxis (33.3%), urticaria, and/or angioedema (58.3%) were more common in the allergic group. Unspecified rashes (35.0%) and nonspecific symptoms (28.3%) predominated in the nonallergic group.

CONCLUSION

Only 28.6% of patients with self-reported penicillin allergy were confirmed to be allergic. Importantly, when the index drug is amoxicillin-clavulanic acid or flucloxacillin, the patients may tolerate amoxicillin.

Utility of minor determinants for skin testing in inpatient penicillin allergy evaluation

BACKGROUND

Most patients with a history of penicillin allergy can tolerate penicillin. Skin testing can identify tolerant patients, but not all known allergenic determinants are commercially available. Protocols exist that use only available reagents, but the sensitivity and safety of these protocols, particularly for hospitalized patients, are controversial.

OBJECTIVE

To determine the number of hospitalized patients referred for penicillin skin testing who showed unique positivity to the minor determinants penicilloate and penilloate.

METHODS

A retrospective chart review was conducted of all inpatients who underwent penicillin skin testing at 1 institution. Patients were referred by their treating physician. All patients underwent skin prick testing to benzylpenicilloyl polylysine (major determinant), penicillin G, penicilloate, penilloate (minor determinants), amoxicillin, and positive and negative controls. If the result was negative, then intradermal testing was done with the same penicillin determinants and the negative control. A 4-mm wheal with flare was considered a positive reaction.

RESULTS

Inpatient penicillin skin testing was done in 528 subjects. Any positive test reaction was found in 107 subjects (20%). Three subjects (3%) reacted to penilloate only, 25 (23%) reacted to penicilloate only, 2 (2%) reacted to penicillin G only, and 8 (8%) reacted to amoxicillin only. Sixty-eight subjects (64%) reacted to a compound other than the major determinant.

CONCLUSION

This study found a high rate of exclusively positive skin test reactions to the minor determinants penicilloate and penilloate. Because patients with positive test reactions are at increased risk of reaction to drug challenge, these data support the use of these reagents for penicillin skin testing in hospitalized patients.

Pharmacogenomics of off-target adverse drug reactions

Off-target adverse drug reactions (ADRs) are associated with significant morbidity and costs to the healthcare system, and their occurrence is not predictable based on the known pharmacological action of the drug's therapeutic effect. Off-target ADRs may or may not be associated with immunological memory, although they can manifest with a variety of shared clinical features, including maculopapular exanthema, severe cutaneous adverse reactions (SCARs), angioedema, pruritus and bronchospasm. Discovery of specific genes associated with a particular ADR phenotype is a foundational component of clinical translation into screening programmes for their prevention. In this review, genetic associations of off-target drug-induced ADRs that have a clinical phenotype suggestive of an immunologically mediated process and their mechanisms are highlighted. A significant proportion of these reactions lack immunological memory and current data are informative for these ADRs with regard to disease pathophysiology, therapeutic targets and biomarkers which may identify patients at greatest risk. Although many serious delayed immune-mediated (IM)-ADRs show strong human leukocyte antigen associations, only a small subset have successfully been implemented in screening programmes. More recently, other factors, such as drug metabolism, have been shown to contribute to the risk of the IM-ADR. In the future, pharmacogenomic targets and an understanding of how they interact with drugs to cause ADRs will be applied to drug design and preclinical testing, and this will allow selection of optimal therapy to improve patient safety.

Long-term reproducibility of positive patch test reactions in patients with non-immediate cutaneous adverse drug reactions to antibiotics

BACKGROUND

As in contact allergy, T cell-mediated hypersensitivity in non-immediate (NI) cutaneous adverse drug reactions (CADRs) to antibiotics is considered to be lifelong, but, in this setting, patch tests have rarely been repeated after long time intervals.

OBJECTIVE

To evaluate the long-term reproducibility of positive patch test reactions to antibiotics in patients with NI CADRs.

METHODS

Fifty-six patients with NI CADRs to antibiotics who had relevant positive reactions during patch testing were invited to repeat patch tests with a similar antibiotic series 2-15 years thereafter.

RESULTS

Twenty patients were included (9 males and 11 females; mean age 54.6 years): 18 with maculopapular exanthema, 1 with drug hypersensitivity syndrome, and 1 with acute generalized exanthematous pustulosis. Results were reproducible in 17 of 20 patients after a mean interval of 6.0 years (range 2-14.7 years). Concerning β-lactams, 7 of 8 patients remained positive for aminopenicillins, 4 of 4 for isoxazolyl penicillins, and 1 for cefoxitin. Patch test results were also reproducible for clindamycin in 5 of 7 patients, for vancomycin in 1 patient, and for spiramycin in 1 patient. Reproducibility was not affected by the time interval between tests, sex, or age at testing.

CONCLUSIONS

In the context of NI CADRs, we showed high reproducibility of positive patch test reactions to various antibiotics, even after several years.

Prevalence of beta-lactam allergy: a retrospective chart review of drug allergy assessment in a predominantly pediatric population

Background

Research suggests that 90% of patients labeled beta-lactam allergic are able to tolerate penicillins following further assessment. This study aims to define and describe the frequency of true beta-lactam allergy following allergy patient evaluation in a predominantly pediatric population.

Methods

306 primary care patients referred between January 2010 and June 2015 were assessed for a suspected beta-lactam allergy. Patient demographics, history and test results were extracted from electronic medical records. Testing performed was based on specialist recommendation following review of patient history.

Results

34% of the study participants had intradermal testing. Oral challenge was given to 96.7% of the sample. 96% of patients with a prior history of beta-lactam allergy were advised that they could re-introduce beta-lactam antibiotics following evaluation.

Conclusions

Among patients with a documented beta-lactam allergy or a recent history of a reaction there is a low rate of ‘true’ beta-lactam allergy. Consistent evaluation of beta-lactam antibiotic allergies can reduce rates of broad spectrum antibiotic prescribing, among other harmful consequences.

A Proactive Approach to Penicillin Allergy Testing in Hospitalized Patients

BACKGROUND

Penicillin allergy testing is underutilized in inpatients despite its potential to immediately impact antibiotic treatment. Although most tested patients are able to tolerate penicillin, limited availability and awareness of this tool leads to the use of costly and harmful substitutes.

OBJECTIVE

We established an inpatient service at a large academic hospital to identify and test patients with a history of penicillin allergy with the goals of removing inaccurate diagnoses, reducing the use of beta-lactam alternatives, and educating patients and clinicians about the procedure.

METHODS

Eligible inpatients were flagged daily through the electronic medical record and prioritized via a specialized algorithm. A trained clinical pharmacist performed penicillin skin tests and challenges preemptively or by provider request. Clinical characteristics and antibiotic use were analyzed in tested patients.

RESULTS

A total of 1203 applicable charts were detected by our system leading to 252 direct evaluations over 18 months. Overall, 228 subjects (90.5%) had their penicillin allergy removed. Of these, 223 were cleared via testing and 5 by discovery of prior penicillin tolerance. Among patients testing negative, 85 (38%) subsequently received beta-lactams, preventing 504 inpatient days and 648 outpatient days on alternative agents.

CONCLUSIONS

Penicillin allergy testing using a physician-pharmacist team model effectively removes reported allergies in hospitalized patients. The electronic medical record is a valuable asset for locating and stratifying individuals who benefit most from intervention. Proactive testing substantially reduces unnecessary inpatient and outpatient use of beta-lactam alternatives that may otherwise go unaddressed.

Clinical History-Driven Diagnosis of Allergic Diseases: Utilizing in vitro IgE Testing

This case illustrates the importance of a thorough clinical history in providing an interpretation of previously collected IgE antibody serology as part of a workup for allergic disease. Although a yellow-jacket sting was the allergenic insult that led the patient to the emergency department, nonindicated IgE antibody serology tests were ordered that subsequently required interpretation. This report systematically evaluates the relative significance of previously measured IgE antibody serology responses to 4 major allergen groups (inhalants [aeroallergens], foods, venoms, and drugs) within the context of the patient's history. An algorithm that takes into account the pretest likelihood of disease and diagnostic sensitivity and specificity of the available IgE antibody tests is proposed for decisions about further IgE testing. This case study concludes that selection of testing methods, extract and molecular allergen specificities, and the final interpretation of the results from tests of sensitization such as serological (in vitro) IgE antibody assays requires knowledge of test parameters and clinical judgments based largely on a carefully collected clinical history and physical examination.