Allergy to penicillin: fable or fact?

The role of in vitro testing in pharmacovigilance for ß-lactam-induced serum sickness-like reaction: A pilot study

Background: Current pharmacovigilance (PV) methods for detection of adverse drug reactions (ADRs) fail to capture rare immune-mediated drug hypersensitivity reactions (DHRs) due to their scarcity and the lack of clear diagnostic criteria. Drug-induced serum sickness-like reactions (SSLRs) are rare type of DHRs that occur in susceptible patients 1–3 weeks after exposure to the culprit drug with ß-lactam antibiotics being the most associated drugs. The diagnosis of drug induced SSLR is difficult due to the lack of safe and reliable diagnostic tests for identifying the culprit drug. The lymphocyte toxicity assay (LTA) is an in vitro test used as a diagnostic tool for drug hypersensitivity reactions (DHRs).

Objective: To evaluate the role of the LTA test for diagnosing and capturing SSLR due to ß-lactam antibiotics in a cohort of patients.

Methods: Patients were recruited from patients referred to the Drug Hypersensitivity Clinic at Clinic at London Health Science Centre with suspicion of drug allergy. Twenty patients (10 males and 10 females) were selected to be tested to confirm diagnosis. Demographic data was collected form the patents and blood samples were withdrawn from all patients and from 20 healthy controls. The LTA test was performed on all subjects and data is expressed as percentage increase in cell death compared to control (vehicle without the drug).

Results: In the result of LTA tests performed on samples from the selected 20 patients. There was a significant (p < 0.05) concentration-dependent increase in cell death in cells isolated from patients as compared to cells from healthy controls when incubated with the drug in the presence of phenobarbitone-induced rat liver microsomes.

Conclusion: Giving its safety and good predictive value the LTA test has very strong potential to be a useful diagnostic tool for ß-lactam-induced SSLR. The test procedure is relatively simple and not overly costly. Further studies including other drug classes are needed to evaluate the utility of the LTA test for SSLR due to other drugs.

Perinatal outcome and long-term infectious hospitalizations of offspring born to women with known drug allergy

PROBLEM

Maternal drug allergy has been associated with altered immune status and an inflammatory environment, which may affect the risk of future infectious diseases in the offspring.

OBJECTIVES

We aimed to evaluate perinatal outcomes and long-term infectious hospitalization in the offspring of women with documented drug allergy.

METHOD OF STUDY

The study was conducted at the Soroka University Medical Center, a tertiary medical center. For perinatal outcomes, generalized estimation equation (GEE) models were used controlling for maternal age, maternal diabetes mellitus, smoking, and hypertensive disorders. The study groups were followed until 18 years of age for infectious-related hospitalizations. A Kaplan-Meier survival-curve was used to compare cumulative incidence of long-term infectious hospitalizations. A Cox proportional hazards model was conducted to control for confounders.

RESULTS

During the study period, 243,682 deliveries met the inclusion criteria, of which 9,756 (4.0%) occurred in women with documented drug allergy. Using GEE, maternal drug allergy was found to be a significant independent risk factor for hypertensive disorders, diabetes mellitus, intra-uterine growth restriction (IUGR) and preterm delivery. Offspring also had significantly higher rates of long-term infectious hospitalizations. Kaplan-Meier survival-curves demonstrated significantly higher cumulative incidence rates of infectious hospitalization (log rank p<0. 001). In a Cox proportional hazards model, being born to a mother with documented a drug allergy was independently associated with infectious hospitalization of the offspring in the long-term.

CONCLUSIONS

Maternal documented drug allergy is independently associated with adverse perinatal outcome such as IUGR and preterm delivery and increased risk of long- term infectious hospitalization of the offspring. This article is protected by copyright. All rights reserved.

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.

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.

Reported Knowledge and Management of Potential Penicillin Allergy in Children

BACKGROUND

Pediatric emergency medicine (PEM) and primary care provider (PCP) providers are the most likely physicians to initially label a child as allergic to penicillin. Differences in knowledge and management of reported penicillin allergy between these 2 groups have not been well characterized.

METHODS

A cross-sectional, 20-question survey was administered to PEM and PCPs to ascertain differential knowledge and management of penicillin allergy. Knowledge regarding high- and low-risk symptoms for true allergy and extent of history taking regarding allergy were compared between the 2 groups using t tests, Chi-square, and Wilcoxon tests.

RESULTS

In total, 182 PEM and 54 PCPs completed the survey. PEM and PCPs reported that 74.1 ± 19.5% and 69.0 ± 23.8% of patients with remote low-risk symptoms of allergy could tolerate penicillin without an allergic reaction. PEM and PCPs incorrectly identified low-risk symptoms of allergy as high-risk, including vomiting with medication administration and delayed skin rash. PCPs took more detailed allergy histories when compared with PEM providers. In total, 143 (78.5%) of PEM providers and 51 (94.4%) PCPs were interested in using a penicillin allergy questionnaire to segregate children into high- or low-risk categories.

CONCLUSIONS

Most pediatric providers believe that children with a remote history of low-risk allergy symptoms could tolerate penicillin without an allergic reaction; however, this is infrequently acted upon. Both PEM and PCP providers were likely to classify low-risk symptoms as high-risk and infrequently referred children for further detailed allergy assessment. Both groups were receptive to decision support measures to facilitate improved penicillin allergy classification and labeling and support antibiotic appropriateness in their patients.

Antibiotic Use After Removal of Penicillin Allergy Label

BACKGROUND

Penicillin allergy is commonly reported in the pediatric emergency department. We previously performed 3-tier penicillin allergy testing on children with low-risk symptoms, and 100% tolerated a penicillin challenge without an allergic reaction. We hypothesized that no serious allergic reactions would occur after re-exposure to penicillin and that prescription practices would change after testing.

METHODS

We performed a follow-up case series of 100 children whose test results were negative for penicillin allergy. Research staff administered a brief follow-up phone survey to the parent and primary care provider of each patient tested. We combined the survey data and summarized baseline patient characteristics and questionnaire responses. We then completed a 3-tier economic analysis from the prescription information gathered from surveys in which cost savings, cost avoidance, and potential cost savings were calculated.

RESULTS

A total of 46 prescriptions in 36 patients were reported by the primary care provider and/or parents within the year after patients were tested for penicillin allergy. Twenty-six (58%) of the prescriptions filled were penicillin derivatives. One (4%) child developed a rash 24 hours after starting the medication; no child developed a serious adverse reaction after being given a penicillin challenge. We found that the cost savings of delabeling patients as penicillin allergic was $1368.13, the cost avoidance was $1812.00, and the total potential cost savings for the pediatric emergency department population was $192 223.00.

CONCLUSIONS

Children with low-risk penicillin allergy symptoms whose test results were negative for penicillin allergy tolerated a penicillin challenge without a severe allergic reaction developing. Delabeling children changed prescription behavior and led to actual health care savings.

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.

Allergy Testing in Children With Low-Risk Penicillin Allergy Symptoms

BACKGROUND

Penicillin allergy is commonly reported in the pediatric emergency department (ED). True penicillin allergy is rare, yet the diagnosis results from the denial of first-line antibiotics. We hypothesize that all children presenting to the pediatric ED with symptoms deemed to be low-risk for immunoglobulin E-mediated hypersensitivity will return negative results for true penicillin allergy.

METHODS

Parents of children aged 4 to 18 years old presenting to the pediatric ED with a history of parent-reported penicillin allergy completed an allergy questionnaire. A prespecified 100 children categorized as low-risk on the basis of reported symptoms completed penicillin allergy testing by using a standard 3-tier testing process. The percent of children with negative allergy testing results was calculated with a 95% confidence interval.

RESULTS

Five hundred ninety-seven parents completed the questionnaire describing their child's reported allergy symptoms. Three hundred two (51%) children had low-risk symptoms and were eligible for testing. Of those, 100 children were tested for penicillin allergy. The median (interquartile range) age at testing was 9 years (5-12). The median (interquartile range) age at allergy diagnosis was 1 year (9 months-3 years). Rash (97 [97%]) and itching (63 [63%]) were the most commonly reported allergy symptoms. Overall, 100 children (100%; 95% confidence interval 96.4%-100%) were found to have negative results for penicillin allergy and had their labeled penicillin allergy removed from their medical record.

CONCLUSIONS

All children categorized as low-risk by our penicillin allergy questionnaire were found to have negative results for true penicillin allergy. The utilization of this questionnaire in the pediatric ED may facilitate increased use of first-line penicillin antibiotics.

Parent-Reported Penicillin Allergy Symptoms in the Pediatric Emergency Department

OBJECTIVE

Children often present to the pediatric emergency department (ED) with a reported penicillin allergy. The true incidence of pediatric penicillin allergy is low, and patients may be inappropriately denied first-line antibiotics. We hypothesized that more than 70% of reported penicillin allergies in the pediatric ED are low risk for true allergy.

METHODS

Parents of children presenting to the pediatric ED with parent-reported penicillin allergy completed an allergy questionnaire. The questionnaire included age at allergy diagnosis, symptoms of allergy, and time to allergic reaction from first dose. The allergy symptoms were dichotomized into high and low risk in consultation with a pediatric allergist before questionnaire implementation.

RESULTS

A total of 605 parents were approached; 500 (82.6%) completed the survey. The median (interquartile range) age of the children at diagnosis was 1 year (7 months, 2 years); 75% were diagnosed before their third birthday. Overall, 380 (76%) (95% confidence interval 72.3, 79.7) children had exclusively low-risk symptoms. The most commonly reported symptoms were rash (466, 92.8%) and itching (203, 40.6%). Of the 120 children with one or more high-risk symptom, facial swelling (50, 10%) was the most common. Overall, 354 children (71%) were diagnosed after their first exposure to penicillin. Symptom onset within 24 hours of medication administration occurred in 274 children (54.8%).

CONCLUSIONS

Seventy-six percent of patients with parent-reported penicillin allergy have symptoms unlikely to be consistent with true allergy. Determination of true penicillin allergy in patients with low-risk symptoms may permit the increased use of first-line penicillin antibiotics.

Prophylactic Antibiotic Choice and Risk of Surgical Site Infection After Hysterectomy

OBJECTIVE

To evaluate associations between prophylactic preoperative antibiotic choice and surgical site infection rates after hysterectomy.

METHODS

A retrospective cohort study was performed of patients in the Michigan Surgical Quality Collaborative undergoing hysterectomy from July 2012 to February 2015. The primary outcome was a composite outcome of any surgical site infection (superficial surgical site infections or combined deep organ space surgical site infections). Preoperative antibiotics were categorized based on the recommendations set forth by the American College of Obstetricians and Gynecologists and the Surgical Care Improvement Project. Patients receiving a recommended antibiotic regimen were categorized into those receiving β-lactam antibiotics and those receiving alternatives to β-lactam antibiotics. Patients receiving nonrecommended antibiotics were categorized into those receiving overtreatment (excluded from further analysis) and those receiving nonstandard antibiotics. Multivariable logistic regression models were developed to estimate the independent effect of antibiotic choice. Propensity score matching analysis was performed to validate the results.

RESULTS

The study included 21,358 hysterectomies. The overall rate of any surgical site infection was 2.06% (n=441). Unadjusted rates of "any surgical site infection" were 1.8%, 3.1%, and 3.7% for β-lactam, β-lactam alternatives, and nonstandard groups, respectively. After adjusting for patient and operative factors within clusters of hospitals, compared with the β-lactam antibiotics (reference group), the risk of "any surgical site infection" was higher for the group receiving β-lactam alternatives (odds ratio [OR] 1.7, confidence interval [CI] 1.27-2.07) or the nonstandard antibiotics (OR 2.0, CI 1.31-3.1).

CONCLUSION

Compared with women receiving β-lactam antibiotic regimens, there is a higher risk of surgical site infection after hysterectomy among those receiving a recommended β-lactam alternative or nonstandard regimen.

Documenting Penicillin Allergy: The Impact of Inconsistency

BACKGROUND

Allergy documentation is frequently inconsistent and incomplete. The impact of this variability on subsequent treatment is not well described.

OBJECTIVE

To determine how allergy documentation affects subsequent antibiotic choice.

DESIGN

Retrospective, cohort study.

PARTICIPANTS

232,616 adult patients seen by 199 primary care providers (PCPs) between January 1, 2009 and January 1, 2014 at an academic medical system.

MAIN MEASURES

Inter-physician variation in beta-lactam allergy documentation; antibiotic treatment following beta-lactam allergy documentation.

KEY RESULTS

15.6% of patients had a reported beta-lactam allergy. Of those patients, 39.8% had a specific allergen identified and 22.7% had allergic reaction characteristics documented. Variation between PCPs was greater than would be expected by chance (all p<0.001) in the percentage of their patients with a documented beta-lactam allergy (7.9% to 24.8%), identification of a specific allergen (e.g. amoxicillin as opposed to "penicillins") (24.0% to 58.2%) and documentation of the reaction characteristics (5.4% to 51.9%). After beta-lactam allergy documentation, patients were less likely to receive penicillins (Relative Risk [RR] 0.16 [95% Confidence Interval: 0.15-0.17]) and cephalosporins (RR 0.28 [95% CI 0.27-0.30]) and more likely to receive fluoroquinolones (RR 1.5 [95% CI 1.5-1.6]), clindamycin (RR 3.8 [95% CI 3.6-4.0]) and vancomycin (RR 5.0 [95% CI 4.3-5.8]). Among patients with beta-lactam allergy, rechallenge was more likely when a specific allergen was identified (RR 1.6 [95% CI 1.5-1.8]) and when reaction characteristics were documented (RR 2.0 [95% CI 1.8-2.2]).

CONCLUSIONS

Provider documentation of beta-lactam allergy is highly variable, and details of the allergy are infrequently documented. Classification of a patient as beta-lactam allergic and incomplete documentation regarding the details of the allergy lead to beta-lactam avoidance and use of other antimicrobial agents, behaviors that may adversely impact care quality and cost.

Utility of penicillin allergy testing in patients presenting with a history of penicillin allergy

Background

Current statistics show that approximately 10% of patients claim to be allergic to penicillin yet only 10% of these have demonstrable allergy. The most appropriate and cost-effective antibiotics are sometimes withheld on the basis of patient history of drug allergy.

Objective

Investigation of IgE hypersensitivity and delayed hypersensitivity in patients with a history of penicillin allergy to a teaching hospital allergy clinic.

Methods

Patients underwent skin prick and intradermal testing (IDT) with major and minor penicillin determinants. Those with negative skin tests were administered a three-day oral challenge. Demographic and clinical details about the reactions were noted.

Results

One hundred twenty eight patients underwent testing, of these, one hundred and ten had self-reported histories of penicillin allergy and eighteen were referred because of other antibiotic allergies. Seventeen patients with self-reported penicillin allergy had either positive skin tests or oral challenge results, corresponding to 15% of patients having proven allergy. None reacted on skin prick testing, four reacted to IDT, thirteen reacted to oral challenge (five immediate and eight delayed). Analysis of clinical histories showed that patients with a well-defined history of allergy and a history of anaphylaxis were more likely to have a positive test compared to patients with vague histories. Skin testing proved to be less sensitive than oral challenge.

Conclusion

A minority of patients presenting with a history of penicillin allergy have evidence of immune-mediated hypersensitivity (17/110, 15%) in this study. Of these, eight out of seventeen (47%) had delayed reactions, demonstrating the usefulness and discriminating power of objective testing, which must include three-day oral challenge. Discriminating factors for immune-mediated allergy from patient history were a clear description of the original reaction and a history of anaphylaxis. Negative allergy testing enables the use of penicillin as first-line treatment when necessary and this can significantly reduce costs of antibiotics.

Is drug allergy less prevalent than previously assumed? A 5-year analysis

BACKGROUND

Rashes are a frequent conundrum in clinical practice as they may be reactive, drug induced or disease specific. Identification of the culprit drug is important as re-exposure may be harmful or even life-threatening and unnecessary avoidance of 'innocent' drugs leads to limitations of treatment options.

OBJECTIVE

To objectify the cause of suspected cutaneous drug reactions in a large patient population.

METHOD

Over 5years (2006-10), 612 patients with suspected cutaneous drug reactions were evaluated. Histology was assessed. About 200 patients were invited for complete work-up with skin tests (prick/intracutaneous testing and scratch/patch as indicated) and, if necessary, lymphocyte transformation tests (LTT). In special cases, drug provocation tests were conducted.

RESULTS

A total number of 141 cases with suspected drug reaction underwent full work-up (age 6-86years; 75% female, 25% male). In 107 cases (76%) a drug was identified whereas 34 (24%) were reactive rashes or had other causes. Mostly, cutaneous drug reactions were maculopapular rashes, urticaria/angio-oedema; less frequently, acute generalized exanthematous pustulosis, drug reaction with eosinophilia and systemic symptoms, systemic drug-related intertriginous and flexural exanthema, toxic epidermal necrolysis and fixed drug eruptions were present. Of all the cutaneous drug reactions investigated, 39·8% were caused by antibiotics, 21·2% by anti-inflammatories, 7·6% by contrast media and 31·4% by others (oral antidiabetics, antimycotics, antipsychotics, antiepileptics and others).

CONCLUSION

Clinical assessment overestimates the role of drug allergies in cutaneous reactions. Assessment of suspected drug reactions can be greatly improved by thorough evaluation including dermatological and allergological work-up with skin testing and assays such as LTT.

Impact of an antimicrobial allergy label in the medical record on clinical outcomes in hospitalized patients

STUDY OBJECTIVE

To determine the impact of having an antimicrobial allergy label in the medical record on clinical outcomes in hospitalized patients.

DESIGN

Retrospective cohort study.

SETTING

Urban academic teaching hospital.

PATIENTS

A total of 11,872 adults admitted to nonsurgical patient care wards who received at least one antimicrobial between August 1, 2007, and July 31, 2008; of these patients, 1324 (11.2%) had an antimicrobial allergy label and 10,548 (88.8%) did not have an allergy label documented in the medical record.

MEASUREMENTS AND MAIN RESULTS

The following clinical outcomes were compared in patients with allergy labels versus patients without allergy labels: length of stay, admission to the intensive care unit (ICU), number of antimicrobials received during hospitalization, readmission within 4 weeks of hospital discharge, and death during hospitalization. Presence of an allergy label in the medical record was associated with increased length of stay, a higher ICU admission rate, receipt of more than one antimicrobial, and a higher mortality rate during the hospitalization. Logistic regression models were used to assess the association of allergy label with these outcomes while adjusting for covariates (age group, sex, surgery during hospitalization, and season of admission); multiple regression was used to model the association of allergy label with length of stay. On average, length of stay was 1.21 days (unadjusted) and 1.16 days (adjusted for covariates) longer in patients with allergy labels. The likelihood of an ICU admission were 1.4 times (adjusted odds ratio [OR] 1.42, 95% confidence interval [CI] 1.21-1.67) higher in patients with allergy labels. Presence of an allergy label was also associated with receipt of more than one antibiotic during the hospitalization (crude OR 1.61, 95% CI 1.43-1.81) and a 1.6-fold higher risk of dying during the hospitalization (crude OR 1.56, 95% CI 1.20-2.04). Presence of an allergy label was not associated with an increased risk of readmission within 4 weeks of discharge (adjusted OR 0.71, 95% CI 0.63-0.80).

CONCLUSION

Presence of an allergy label in the medical record was associated with increased length of hospital stay and worse clinical outcomes compared with no allergy label in hospitalized patients treated with antimicrobials.

The use of cephalosporins in penicillin-allergic patients: a literature review

BACKGROUND

The practice of avoiding cephalosporin administration to penicillin-allergic patients persists despite the low rate of cross reactions between both groups of antibiotics.

OBJECTIVE

The purpose of this literature review is to evaluate the published evidence regarding the commonly held belief that patients with a history of an allergic reaction to penicillin have a significantly increased risk of an allergic reaction to cephalosporins.

MATERIALS AND METHODS

Articles were identified through a computerized search of MEDLINE from 1950 to the present using the search terms "penicillin$," "cephalosporin$," "allerg$," "hypersensitivity," and "cross-react$." All articles were reviewed, and additional sources cited in them were added to the literature review.

RESULTS

Penicillins have a cross allergy with first-generation cephalosporins (odds ratio 4.8; confidence interval 3.7-6.2) and a negligible cross allergy with second-generation cephalosporins (odds ratio 1.1; confidence interval 0.6-2.1). Laboratory and cohort studies confirm that the R1 side chain is responsible for this cross reactivity. Overall cross reactivity between penicillins and cephalosporins is lower than previously reported, though there is a strong association between amoxicillin and ampicillin with first- and second-generation cephalosporins that share a similar R1 side chain.

CONCLUSIONS

Although a myth persists that approximately 10% of patients with a history of penicillin allergy will have an allergic reaction if given a cephalosporin, the overall cross-reactivity rate is approximately 1% when using first-generation cephalosporins or cephalosporins with similar R1 side chains. However, a single study reported the prevalence of cross reactivity with cefadroxil as high as 27%. For penicillin-allergic patients, the use of third- or fourth-generation cephalosporins or cephalosporins with dissimilar side chains than the offending penicillin carries a negligible risk of cross allergy.

The use of penicillin skin testing to assess the prevalence of penicillin allergy in an emergency department setting

STUDY OBJECTIVE

Patient-reported penicillin allergies are often unreliable and can result in unnecessary changes in antibiotic therapy. Although penicillin allergy skin testing is commonly performed in allergy clinics, it has not been used in emergency departments (EDs) to verify self-reported allergies. We hypothesize that ED-based testing is possible and that the false-positive rate of patients with self-reported penicillin allergy are greater than 90%.

METHODS

This prospective observational cohort study enrolled a convenience sample of ED patients with a self-reported penicillin allergy. Patients were enrolled by one of 2 emergency physicians who performed skin prick and intracutaneous tests with penicillin major and minor determinants. The total testing time was 30 minutes. The proportion of false-positive self-reported allergies was computed with 95% confidence intervals (CIs) by using the score method.

RESULTS

A total of 150 patients (mean age 42 years; SD 16 years; 46% men; 47% black) were enrolled. The false-positive rate for self-reported penicillin allergy was 137 of 150 (91.3%; 95% CI 85.3% to 95.1%). There were no adverse reactions associated with penicillin skin testing. Compared with patients with a false-positive penicillin allergy result (confirmed by negative penicillin skin testing result), patients reporting a true penicillin allergy confirmed by positive penicillin skin test results tended to be more frequently men (61.5% versus 44.5%; Delta 17.0%; 95% CI -13.5% to 42%), black (69.2% versus 44.5%; Delta 24.7%; 95% CI -6.9% to 46.8%), and have no family history of drug allergy (7.7% versus 17.5%; Delta9.8%; 95% CI -20.9% to 20.4%), but self-reported other drug allergies more frequently (61.5% versus 38.7%; Delta 22.9%; 95% CI -7.7% to 47.5%).

CONCLUSION

Penicillin skin testing is feasible in the ED setting. A substantial number of patients who self-report a penicillin allergy do not exhibit immunoglobulin E-mediated sensitization to penicillin major and minor determinants. Penicillin testing in the ED may allow the use of more appropriate antibiotics for patients presenting with a history of penicillin allergy.

Skin testing and oral penicillin challenge in patients with a history of remote penicillin allergy

BACKGROUND

Penicillin administration is usually contraindicated in penicillin-allergic patients with positive skin test results.

OBJECTIVE

To examine whether penicillin oral challenge for patients with a history of remote non-life-threatening allergic reaction to penicillin can be well tolerated irrespective of skin test results.

METHODS

In a prospective open-label trial, 8,702 individuals were screened between November 1998 and January 2000. Of 687 patients with a non-life-threatening allergic reaction to penicillin, occurring longer than 3 years earlier, 169 were enrolled. Regardless of the response to penicillin skin testing, patients received the usual 1-day dosage of penicillin and amoxicillin, on 2 separate occasions. Two to 6 years later, a follow-up was conducted to assess the outcomes of further penicillin administration.

RESULTS

A total of 272 combined skin tests and oral challenges were performed on 169 patients. Among 137 challenges with a positive skin test result and 135 patients with a negative skin test result, 9 (6.6%) and 5 (3.7%) (P = .29), respectively, developed a mild rash to oral challenge. At follow-up, 2 to 6 years afterward, 3 of 55 patients (5.5%) who were given a full treatment course of penicillin developed a mild skin eruption.

CONCLUSIONS

Positive penicillin skin test results for patients with a remote history of non-life-threatening allergic reaction to penicillin were not associated with a greater prevalence of adverse reactions to oral challenge with penicillin than negative results. Because skin testing is considered the gold standard and the safest method for predicting tolerance to penicillin administration, oral penicillin challenge may be used as a diagnostic method only in these specific patients when skin testing is not feasible.

Aminopenicillin-induced exanthema allows treatment with certain cephalosporins or phenoxymethyl penicillin

OBJECTIVES

Aminopenicillin-induced exanthema poses a problem in the management of infectious diseases. Due to theoretically possible immunological cross-reactivity, all beta-lactam drugs, i.e. penicillins, penicillin derivatives and cephalosporins, are usually avoided. The available alternative antibiotics (macrolides, quinolones and glycopeptides) may be less effective, have more side effects, and their use increases medical costs. Moreover, their use contributes to the increasing bacterial resistance to antibiotics. The aim of the study is to demonstrate that patients with aminopenicillin-induced exanthema may receive specific beta-lactams for future antibiotic therapy.

METHODS

Skin testing followed by oral challenges to identify beta-lactams that are tolerated by patients despite confirmed delayed-type non-immunoglobulin E (IgE)-mediated allergic hypersensitivity to aminopenicillins.

RESULTS

Sixty-nine out of 71 patients (97.2%) with non-IgE-mediated allergic hypersensitivity to aminopenicillins tolerate cephalosporins without an aminobenzyl side chain such as cefpodoxime or cefixime and 51 patients (71.8%) also tolerate phenoxymethyl penicillin.

CONCLUSIONS

The majority of patients with non-IgE-mediated allergic hypersensitivity to aminopenicillins do not cross-react to certain cephalosporins or phenoxymethyl penicillin. Skin and drug challenge tests can be helpful to determine individual cross-reactivity.

Antibiotic selection in the penicillin-allergic patient

Clinicians should be familiar with which antibiotics are safe to use for different types of penicillin-allergic reactions. Clinically, it is convenient to divide patients with penicillin allergy into three categories: those with unknown or possible reactions to penicillin, those with a drug fever or rash, and those with hives or anaphylactic reactions. Beta-lactam antibiotics may be used safely for patients with unknown/possible penicillin allergy and drug fever or rash. Penicillins or beta-lactams should not be used for patients with hives or anaphylactic reactions. For all patients, clinicians should consider antimicrobial therapy with an antibiotic that does not cross-react with penicillins or beta-lactams. This article reviews how clinicians should select antimicrobials in penicillin-allergic patients.

A review of evidence supporting the American Academy of Pediatrics recommendation for prescribing cephalosporin antibiotics for penicillin-allergic patients

The American Academy of Pediatrics, evidence-based guidelines endorse the use of cephalosporin antibiotics for patients with reported allergies to penicillin, for the treatment of acute bacterial sinusitis and acute otitis media. Many physicians, however, remain reluctant to prescribe such agents. Although such concern is understandable, lack of consistent data regarding exactly what constitutes an initial penicillin-allergic reaction and subsequent cross-sensitivity to cephalosporins may be preventing many patients from receiving optimal antibiotic therapy. This article reviews evidence in support of the American Academy of Pediatrics recommendation. Included is an examination of the types and incidence of reactions to penicillins and cephalosporins; the frequency of cross-reactivity between these 2 groups of agents; experimental and clinical studies that suggest that side chain-specific antibodies predominate in the immune response to cephalosporins, thereby explaining the lack of cross-sensitivity between most cephalosporins and penicillins; the role of skin testing; and the risks of anaphylaxis. Specific recommendations for the treatment of patients on the basis of their responses to previously prescribed agents are summarized.

Is it safe to use carbapenems in patients with a history of allergy to penicillin?

OBJECTIVES

The purpose of this retrospective study was to ascertain the clinical safety of administering carbapenems, namely imipenem/cilastatin and meropenem, in patients with a history of penicillin allergy compared with administering carbapenems in patients with no reported penicillin allergy. Carbapenems are similar in chemical structure to the penicillins and therefore are associated with a risk for allergic cross-hypersensitivity. Carbapenems are commonly avoided in patients with a reported penicillin allergy on the basis of a potential cross-hypersensitivity with penicillin, however, very few studies have been conducted describing the incidence of cross-hypersensitivity between penicillin and carbapenems.

METHODS

A retrospective review was conducted in a total of 266 patients who were administered either imipenem/cilastatin or meropenem. The patients were admitted to the Cleveland Clinic Health System--Eastern Region Hospitals during the years 2001 and 2002.

RESULTS

Fifteen of the 163 patients (9.2%) with reported penicillin allergy developed a hypersensitivity reaction to meropenem or imipenem/cilastatin whereas 3.9% of the 103 patients without penicillin allergy developed a hypersensitivity reaction to meropenem or imipenem/cilastatin. These results are not statistically significant.

CONCLUSIONS

Based on this study and other similar studies, the true incidence of cross-hypersensitivity reactions between penicillin and carbapenems may be lower than previously reported. Carbapenem use may be reasonable for penicillin allergic patients if caution is exercised.

Documented allergies of patients with cancer

The purpose of this study was to determine and quantify the types of allergies that occur in patients with cancer. The study sample consisted of computer-generated pharmacy records of 4510 inpatients from two oncology inpatient units over a 1-year period from a large urban hospital in the USA. Compliance with computer entry was monitored in order to ensure data accuracy. Results of the study indicate that the percentages of stated allergies for persons with cancer might be higher than those for overall populations. The top four medication allergies were penicillin, sulpha, codeine and contrast media. The top four food allergies were milk, eggs, chocolate and strawberries and the top four environmental allergies were bee stings, chemical sprays, dust and mould.

The economic burden of antibiotic treatment of penicillin-allergic patients in internal medicine wards of a general tertiary care hospital

BACKGROUND

Penicillin allergy poses a major problem in the management of infectious diseases.

OBJECTIVE

We estimated the costs and usage of antibiotic treatment of 'penicillin-allergic' patients in comparison to non-allergic patients in a tertiary care hospital.

MATERIALS AND METHODS

The study was based on the records of 118 randomly chosen in-hospital patients labelled as being 'allergic to penicillin' and who were treated with antibiotics. The antibiotic selection and cost of the patients with alleged penicillin allergy were compared to 118 matched patients without an antibiotic allergy (controls).

RESULTS

During in-hospital treatment, the mean antibiotic cost for penicillin-allergic patients was 63% higher than the cost for the controls. In addition, there was a 38% higher cost of the recommended anti-microbial treatment regimen to be followed upon discharge by the former compared to the latter.

CONCLUSIONS

Penicillin-allergic patients were more likely to receive broader spectrum antibiotics compared to the non-allergic ones. Since many of the patients who are labelled as being 'allergic to penicillin' are, in fact, not allergic to it, inaccurate reporting of penicillin allergies may have costly economic and epidemiologic repercussions in addition to more toxic effects which can occur when choosing alternative drugs in case of penicillin allergy.

A pilot study of penicillin skin testing in patients with a history of penicillin allergy admitted to a medical ICU

BACKGROUND

Penicillin skin testing is an accurate method to determine whether a person with a history of penicillin allergy is at risk of having an immediate reaction to penicillin. A patient with a negative reaction to a skin test may be able to use a penicillin compound safely, which could reduce the use of broad-spectrum antibiotics in this patient population.

METHODS

We prospectively studied all patients with histories of penicillin allergy who were admitted to a medical ICU during a 3-month period and who received antibiotics. Skin testing was performed with benzylpenicilloyl polylysine and penicillin G. We determined the incidence of true allergy, the percentage of patients in whom antibiotic coverage was modified, and the safety of the test.

RESULTS

Two hundred fifty-seven patients were admitted to the medical ICU of The Cleveland Clinic Foundation during the study period. Twenty-four patients (9%), labeled as penicillin allergic and receiving antibiotics, were enrolled. Three patients (13%, 3 of 21) gave histories of type I reaction to penicillin and were not skin tested. Twenty patients (95%, 20 of 21) had negative skin test reactions to penicillin and positive skin test reactions to histamine control. One patient (4%, 1 of 21) with negative skin test reactions to both penicillin and histamine control had a test dose challenge with piperacillin that was well tolerated. There were no adverse events. Antibiotic coverage was changed in 10 patients (48%) as a result of skin testing.

CONCLUSION

Most patients with histories of allergy to penicillin have negative reactions to skin tests and may receive penicillin safely. Penicillin skin testing can be utilized as a safe and effective strategy to reduce the use of broad-spectrum antibiotics.

Early management of meningococcal disease

Meningococcal disease is increasing in incidence in many countries, and effective vaccines for serogroup B strains will not be available for at least 5 to 10 years. In the interim, it is attention to principles of good clinical practice, particularly in the early management of the disease, that have the potential to reduce by half the current case fatality rate of approximately 10%. As discussed in this article, those principles include increased awareness, understanding of the disease and its early symptoms by parents and healthcare professionals, and careful attention to the patient before admission and during the hospital stay.

Clinical use of antibiotics in dental practice

Inappropriate use of antibiotics by clinicians leads to development of antibiotic resistance. For the most part, antibiotics are prescribed in dental practice for prophylactic and therapeutic reasons. Prophylactic antibiotics are prescribed to prevent diseases caused by members of the oral flora introduced to distant sites in a host at risk or introduced to a local compromised site in a host at risk. In most cases, prophylaxis is used for prevention of endocarditis. Therapeutic antibiotics are prescribed, in most cases, to treat diseases of hard and soft tissues in the oral cavity after local debridement has failed. Antibiotics used for prophylaxis must: (1) be active against the major pathogens; and (2) achieve a tissue loading dose before the bacteria are introduced. Antibiotics used for therapy are required in cases where the infection is already present and thus the agent must reach the site of infection at a high enough level for a long enough time to produce the desired effect. For an exogenous agent the goal is to eliminate the agent from the site of infection. In the case of an endogenous agent the antibiotic must suppress the organism at the site of infection. Recent evidence underscores the important role of antibiotics in the treatment and prevention of diseases initiated in the oral cavity that have the potential to spread to distant organs in the body.

A review of pharmacotherapeutics for prosthetic dentistry: Part II

STATEMENT OF PROBLEM

Successful preoperative and postoperative care often depends on systemically administered drugs. The competent and successful practitioner must therefore have a strong background in basic pharmacology, be knowledgeable of pharmacotherapeutics, and keep abreast of the latest advances in medicinal agents.

PURPOSE

The purpose of this article is to review pharmacologic properties of prototype and new drugs that are primarily used to allay anxiety and pain or reduce inflammation and infection. This information should enable clinicians to improve clinical outcomes and make a more knowledgeable assessment and comparison of standard drugs with recently released drugs.

Patients' knowledge about their drug allergies

OBJECTIVE

To investigate the nature and accuracy of information carried by patients about their drug allergies.

SUBJECTS

2500 new adult patients.

SETTING

Accident and emergency department of a tertiary referral centre.

METHODS

Patients were questioned about drug allergies. Where they claimed allergies, general practitioners were contacted for corroboration.

RESULTS

242 patients (9.7%) claimed 276 allergies; 32 different drugs were implicated. Penicillin was implicated most often (151 patients); 38 patients could not remember what they were allergic to; 21 described severe reactions, but four could not remember the drugs involved. Only seven patients carried evidence of their allergies. General practitioners were contacted about 240 of the drug allergies; only 114 were confirmed as described.

CONCLUSIONS

Many patients who believe themselves to have drug allergies are poorly informed about them. Emergency prescribing for these patients may risk anaphylaxis. The future acceptance of "Smart cards"would reduce this risk. In the meantime, patients with drug allergies should be strongly encouraged to carry evidence of their allergies.

Psychiatry in the allergy clinic: the nature and management of patients with non-allergic symptoms

Patients with multiple unexplained somatic symptoms attributed to allergy frequently present to physicians and often the physician fails to find evidence for allergic or immunological mechanisms underlying the presenting symptoms. This article discusses the social and cultural background to this disorder. We then consider current explanatory models for symptoms and finally, we consider appropriate management, starting with the initial consultation, the identification of psychiatric disorders when present, and concluding with suggestions for subsequent treatment and guidance on appropriate referral.

An approach to some dilemmas and complications of office oral surgery

This article reviews an eclectic collection of problems. There is no particular reason why any one of them was chosen other than that they are more likely to occur in the course of practice than some other complications such as an oro-antral fistula or trauma to the lingual nerve or tissue emphysema. These latter and some other predicaments were discussed in the course of the talks given by the author at the 28th Australian Dental Congress in March 1995. The problems discussed in this paper are: 1. Dentoalveolar abscess anaesthesia. 2. Inability to obtain effective anaesthesia. The complications: 1. Post-extraction haemorrhage. 2. Syncope. 3. Postoperative infection.

Radioallergosorbent testing for penicillin allergy in family practice

OBJECTIVES

To determine (a) the prevalence of patients supposedly allergic to penicillin who have a positive radioallergosorbent test (RAST) result for penicillin G or V and (b) the predictive power of family physicians' clinical judgement that a patient who is supposedly allergic to penicillin will have a positive RAST result.

DESIGN

Prospective multicentre cross-sectional observational study.

SETTING

Eleven primary care practices in Newfoundland; 10 were in a rural setting.

PATIENTS

Of 110 consecutive adult patients with a supposed allergy to penicillin 97 agreed to participate in the study; 92 underwent RAST.

INTERVENTIONS

Patients helped physicians complete a questionnaire and had a venous blood sample taken for the RAST. Physicians examined the clinical history and judged whether the patient was likely to have a positive RAST result.

MEAN OUTCOME MEASURES

Rates of positive and negative RAST results for penicillin V and G.

RESULTS

Of the 92 patients 8 had a positive RAST result and 84 a negative one. The positive predictive power of a "good" clinical history (e.g., urticaria, swollen eyes, tongue or lips, or an anaphylactic reaction witnessed by a physician) was low (10%); the negative predictive power of a "poor" clinical history (e.g., nausea, vomiting, diarrhea, fever, nonspecific rash or fainting) was 92%.

CONCLUSIONS

Less than 10% of primary care patients with a supposed allergy to penicillin will have a positive RAST result. In addition, physicians' predictions of allergy in such patients are imprecise.

Immunopharmacology and adverse drug reactions

Adverse drug reactions are common and troublesome complications of contemporary pharmacotherapy. Adverse drug reactions are frequently, and often incorrectly, referred to as "allergy". Although there are multiple mechanisms for adverse drug reactions, adverse drug reactions mediated by the immune system account for a disproportionate number of fatal and serious adverse reactions, and constitute a major clinical problem for patients and physicians. The immune system has evolved in multicellular organisms as a defence against infection. Interactions between drugs and the immune system occur as inadvertent consequences of the protective function of the immune system, with drug molecules or drug-carrier haptens being recognized as "non-self" by the immune system. The classical mechanisms for drug hypersensitivity described by Gell and Coombs (Types 1 to 4) include IgE-mediated, cytotoxic, immune complex-mediated and delayed mechanism. These mechanisms provide elegant models for drug-immune interactions that can provide mechanistic explanations for events such as urticaria associated with penicillins. However, these mechanisms do not account for many of the immunologically mediated adverse reactions commonly encountered in clinical practice. Over the last two decades, there has been an increasing awareness of the importance of reactive drug metabolites and drug-protein interactions in the initiation of immunologic events mediating adverse drug reactions. Reactive drug metabolites may produce direct and profound effects on various functions of the immune system. Although some adverse reactions mediated by the immune system occur with equal frequency among adults and children, some of these reactions appear to be markedly more common among children than adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Meningococcal infections: reducing the case fatality rate by giving penicillin before admission to hospital

OBJECTIVE

To determine whether parenteral penicillin given before admission to hospital reduces the case fatality rate in patients with meningococcal disease.

DESIGN

Retrospective analysis of 46 consecutive patients admitted to hospital with meningococcal disease from January 1986 to March 1991.

SETTING

District general hospital.

MAIN OUTCOME MEASURE

Hospital case fatality rate.

RESULTS

None of the 13 patients given parenteral penicillin by the referring doctor before admission died, compared with eight deaths (24%) in 33 patients admitted without such treatment.

CONCLUSION

Parenteral penicillin given before admission probably contributed to a reduction in the case fatality rate from meningococcal disease, and primary care physicians should be encouraged to give such treatment immediately on suspicion of the diagnosis before transferring the patient to hospital. Public health physicians are well placed to inform and alert general practitioners of the potential benefit of this action.

Early treatment with parenteral penicillin in meningococcal disease

OBJECTIVE

To measure the effect of parenteral antibiotics given before admission to hospital on mortality and on bacteriological investigations in meningococcal disease.

DESIGN

Retrospective review of hospital notes and laboratory and public health medicine department records.

SETTING

Three health districts in south west England.

SUBJECTS

Patients with meningococcal disease in Gloucester district presenting between 1 January 1982 and 31 December 1991 (n = 190); patients with meningococcal disease in Plymouth (n = 118) and Bath (n = 73) districts presenting between 1 January 1988 and 31 December 1991 (total = 381).

MAIN OUTCOME MEASURE

Number of deaths from meningococcal disease.

RESULTS

Parenteral antibiotic given by general practitioners was associated with a substantial reduction in mortality (from 9% to 5%; relative risk 0.6, 95% confidence interval 0.2 to 1.5); patients with a rash were more likely to be given parenteral antibiotics, and mortality was further reduced (from 12% to 5%; 0.5, 0.2 to 1.4). In a district where such treatment was regularly encouraged its use increased from 5% to 40% of cases over 10 years (p = 0.00001). Treatment with parenteral antibiotics before admission made isolation of meningococci from blood and cerebrospinal fluid less likely but did not affect nasopharyngeal cultures.

CONCLUSIONS

General practitioners should carry benzylpenicillin in their emergency bags at all times and should administer it promptly, preferably intravenously, whenever meningococcal disease is suspected, unless the patient has had an anaphylactic reaction to penicillin. Specimens for culture should include a nasopharyngeal swab.