Cephalosporins: A Focus on Side Chains and β-Lactam Cross-Reactivity

Cephalosporins are among the most commonly prescribed antibiotic classes due to their wide clinical utility and general tolerability, with approximately 1-3% of the population reporting a cephalosporin allergy. However, clinicians may avoid the use of cephalosporins in patients with reported penicillin allergies despite the low potential for cross-reactivity. The misdiagnosis of β-lactam allergies and misunderstanding of cross-reactivity among β-lactams, including within the cephalosporin class, often leads to use of broader spectrum antibiotics with poor safety and efficacy profiles and represents a serious obstacle for antimicrobial stewardship. Risk factors for cephalosporin allergies are broad and include female sex, advanced age, and a history of another antibiotic or penicillin allergy; however, cephalosporins are readily tolerated even among individuals with true immediate-type allergies to penicillins. Cephalosporin cross-reactivity potential is related to the structural R1 side chain, and clinicians should be cognizant of R1 side chain similarities when prescribing alternate β-lactams in allergic individuals or when new cephalosporins are brought to market. Clinicians should consider the low likelihood of true cephalosporin allergy when clinically indicated. The purpose of this review is to provide an overview of the role of cephalosporins in clinical practice, and to highlight the incidence of, risk factors for, and cross-reactivity of cephalosporins with other antibiotics.

Point-of-Care β-Lactam Allergy Skin Testing by Antimicrobial Stewardship Programs: A Pragmatic Multicenter Prospective Evaluation

Background

β-lactam allergy skin testing (BLAST) is recommended by antimicrobial stewardship program (ASP) guidelines, yet few studies have systematically evaluated its impact when delivered at point of care.

Methods

We conducted a pragmatic multicenter prospective evaluation of the use of point-of-care BLAST by ASPs. In staggered 3-month intervals, ASP teams at 3 hospitals received training by allergists to offer BLAST for eligible patients with infectious diseases receiving nonpreferred therapy due to severity of their reported allergy. The primary outcome was the proportion of patients receiving the preferred β-lactam therapy.

Results

Of 827 patients with reported β-lactam allergy over 15 months, β-lactam therapy was preferred among 632 (76%). During baseline periods, 50% (124/246) received preferred β-lactam therapy based on history, compared with 60% (232/386) during the intervention periods (P = .02), which improved further to 81% (313/386) upon provision of BLAST (P < .001) without any increase in incidence of adverse drug reactions (4% vs 3%; P = .4). After adjusting for patient variables and the correlation between hospitals, the intervention period was associated with a 4.5-fold greater odds of receiving preferred β-lactam therapy (95% confidence interval, 2.4-8.2; P < .0001).

Conclusions

The use of BLAST at the point of care across 3 hospital ASPs resulted in greater use of preferred β-lactam therapy without increasing the risk of adverse drug reactions. Longer-term studies are needed to better assess the safety and clinical impact of this ASP intervention.

Comparing Direct Challenge to Penicillin Skin Testing for the Outpatient Evaluation of Penicillin Allergy: A Randomized Controlled Trial

BACKGROUND

Direct challenge (DC) may be a safe and effective alternative to penicillin skin testing (PST) in low-risk patients.

OBJECTIVE

To complete a prospective, randomized, controlled trial comparing PST followed by a challenge to amoxicillin versus a 2-step DC to amoxicillin without preceding skin testing in a predefined low-risk patient population.

METHODS

Penicillin allergy histories were reviewed in patients presenting to an outpatient allergy/immunology practice from April 2018 to August 2018. Patients 5 years or older with a cutaneous-only or unknown reaction (>1 year ago for those aged 5-17 years, >10 years ago for those 18 years or older) were randomized 1:1 to PST or 2-step DC. All children younger than 5 years underwent DC, and patients with extracutaneous reaction histories underwent PST. All groups were monitored 30 minutes after administration of amoxicillin.

RESULTS

Penicillin allergy was reported in 363 of 2465 (14.7%) patients, of which 185 consented to further evaluation. Thirteen patients younger than 5 years underwent DC; all were negative. Thirteen patients with angioedema and/or extracutaneous symptoms underwent PST; 2 of 13 patients had positive PST result. A total of 159 patients were randomized to DC (49.7%) or PST (50.3%). PST result was negative in 70 of 80 (87.5%) patients. All 70 patients had a negative amoxicillin challenge. DC was negative in 76 of 79 (96.2%) patients; positive DC reactions were minor. Average time for patients undergoing PST was 72.7 ± 5.3 minutes and for patients undergoing DC was 66.7 ± 4.8 minutes.

CONCLUSIONS

In low-risk patients, DC provided a safe and effective alternative to PST in delabeling penicillin allergy. Compared with PST, DC may also take less time, cost less money, and lead to fewer penicillin allergy evaluations with false-positive results.

The Slow-Motion Catastrophe of Antimicrobial Resistance and Practical Interventions for All Prescribers

All medical and surgical specialties depend on the pool of effective antibiotics that continues to evaporate because of the increasing prevalence of drug-resistant bacteria. Antimicrobial-resistant infections kill 700,000 patients every year. By 2050, they are projected to cause 10 million deaths per year at a cumulative global cost of $100 trillion. Professional societies and international health agencies, including the United Nations, have declared escalating antimicrobial resistance as one of the gravest and most urgent threats to global public health and issued calls for action. The propensity of bacteria to mobilize and share genetic resistance determinants across species and genera, record levels of conflict-driven human population displacement, and the dearth of new antibiotics and rapid diagnostic tests, along with climate change and the epidemic of opioid addiction, exacerbate the antimicrobial resistance crisis. The predominant cause of antibiotic resistance is exposure to antibiotics through appropriate and inappropriate use. Mindfulness, nudging by peers, and adjuncts and alternatives to antibiotics, such as phage therapies, microbiome-based therapies, and novel medical informatics applications, could help reduce antibiotic use. This article describes the antimicrobial resistance crisis and highlights points in the continuum of care in which clinicians can readily implement practical, no-cost changes to minimize antibiotic exposure.

Self-reported beta-lactam intolerance: not a class effect, dangerous to patients, and rarely allergy

Introduction: About 8% of the United States population carries an unconfirmed penicillin 'allergy' in their medical record. Many physicians needlessly avoid other beta-lactam use in individuals with unconfirmed penicillin allergies. There is a significantly increased risk of developing serious antibiotic-resistant infections, and increased morbidity and mortality in those who report penicillin allergy. Areas covered: Within this study, we reviewed the relevant literature on self-reported beta-lactam allergy. We discuss how the myth of serious allergy to penicillin developed and then discuss and in detail clinically significant immunologically mediated hypersensitivity reactions. Following this discussion, we delineate the risks of not using a beta-lactam when it is the drug of choice and then discuss the epidemiology of beta-lactam-associated anaphylaxis, serious cutaneous adverse reactions, and serious systemic immunologically mediated reactions. Following these topics, we further discuss the consensus current best practices to de-label patients with reported penicillin allergy. Expert opinion: An unconfirmed allergy to penicillin offers considerable harm to patients. Many patients have low-risk allergy symptoms to penicillin who could likely tolerate the medication without having an allergic reaction. The current best practices to de-label reported penicillin allergy is the utilization of a single dose oral challenge, with 1 h of observation, in low-risk patients.

Clinical Data on Daptomycin plus Ceftaroline versus Standard of Care Monotherapy in the Treatment of Methicillin-Resistant Staphylococcus aureus Bacteremia

Vancomycin (VAN) and daptomycin (DAP) are approved as a monotherapy for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. A regimen of daptomycin plus ceftaroline (DAP+CPT) has shown promise in published case series of MRSA salvage therapy, but no comparative data exist to compare up-front DAP+CPT head-to-head therapy versus standard monotherapy as an initial treatment. In a pilot study, we evaluated 40 adult patients who were randomized to receive 6 to 8 mg/kg of body weight per day of DAP and 600 mg intravenous (i.v.) CPT every 8 h (q8h) (n = 17) or standard monotherapy (n = 23) with vancomycin (VAN; dosed to achieve serum trough concentrations of 15 to 20 mg/liter; n = 21) or 6 to 8 mg/kg/day DAP (n = 2). Serum drawn on the first day of bacteremia was sent to a reference laboratory post hoc for measurement of interleukin-10 (IL-10) concentrations and correlation to in-hospital mortality. Sources of bacteremia, median Pitt bacteremia scores, Charlson comorbidity indices, and median IL-10 serum concentrations were similar in both groups. Although the study was initially designed to examine bacteremia duration, we observed an unanticipated in-hospital mortality difference of 0% (0/17) for combination therapy and 26% (6/23) for monotherapy (P = 0.029), causing us to halt the study. Among patients with an IL-10 concentration of >5 pg/ml, 0% (0/14) died in the DAP+CPT group versus 26% (5/19) in the monotherapy group (P = 0.057). Here, we share the full results of this preliminary (but aborted) assessment of early DAP+CPT therapy versus standard monotherapy in MRSA bacteremia, hoping to encourage a more definitive clinical trial of its potential benefits against this leading cause of infection-associated mortality. (The clinical study discussed in this paper has been registered at ClinicalTrials.gov under identifier NCT02660346.).

Impact of Reported β-Lactam Allergy on Management of Methicillin-Sensitive Staphylococcus aureus Bloodstream Infections

BACKGROUND

Antistaphylococcal β-lactams antibiotics are the preferred treatment for methicillin-sensitive Staphylococcus aureus (MSSA) infections. Patient-reported β-lactam allergies may complicate antibiotic decision-making and delay optimal therapy, with potential implications on patient outcomes.

OBJECTIVE

To determine the impact of reported β-lactam allergies on the receipt of optimal therapy and outcomes for MSSA bloodstream infections (BSI).

METHODS

Retrospective, matched cohort of MSSA BSI patients with and without a reported β-lactam allergy. The primary end point was receipt of optimal therapy, defined as an antistaphylococcal β-lactam.

RESULTS

Two hundred twelve patients were included: 53 with reported β-lactam allergy and 159 without β-lactam allergy. Commonly reported β-lactam allergies were 26 (49%) immune-mediated reaction and 8 (15%) intolerance, with 19 (36%) having no documented reaction. Optimal antibiotics were given to 135 patients without a β-lactam allergy and 37 patients with a reported β-lactam allergy (85% vs 70%, P = .015). Among reported β-lactam allergy patients, those without a documented reaction were less likely to receive optimal therapy (47% vs 79%, P = .042). Reported β-lactam allergy was not associated with clinical response (P = .61) or MSSA-related mortality (P = .83). When adjusting for immunosuppression, variables independently associated with optimal therapy were β-lactam allergy (adjusted odds ratio [adjOR], 0.3; 95% confidence interval [CI], 0.1-0.6) and infectious diseases consultation (adjOR, 6.1; 95%CI, 2.7-13.9). Optimal antibiotic use was associated with decreased all-cause 90-day mortality (adjOR, 0.23; 95%CI, 0.09-0.54).

CONCLUSIONS

Patients with reported β-lactam allergies, particularly those without a documented reaction, were less likely to receive optimal antibiotics for MSSA BSI. Patient outcomes may be improved with enhanced quality of allergy history and routine infectious disease consultation.

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.

Integrating bedside nurses into antibiotic stewardship: A practical approach

Nurses view patient safety as an essential component of their work and have reported a general interest in embracing an antibiotic steward role. However, antibiotic stewardship (AS) functions have not been formally integrated into nursing practice despite nurses' daily involvement in clinical activities that impact antibiotic decisions (e.g., obtaining specimens for cultures, blood drawing for therapeutic drug monitoring). Recommendations to expand AS programs to include bedside nurses are generating support at a national level, yet a practical guidance on how nurses can be involved in AS activities is lacking. In this review, we provide a framework identifying selected practices where nurses can improve antibiotic prescribing practices through appropriate obtainment of Clostridioides difficile tests, appropriate urine culturing practices, optimal antibiotic administration, accurate and detailed documentation of penicillin allergy histories and through the prompting of antibiotic time outs. We identify reported barriers to engagement of nurses in AS and offer potential solutions that include patient safety principles and quality improvement strategies that can be used to mitigate participation barriers. This review will assist AS leaders interested in advancing the contributions of nurses into their AS programs by discussing education, communication, improvement models, and workflow integration enhancements that strengthen systems to support nurses as valued partners in AS efforts.

Evaluation and Management of Penicillin Allergy: A Review

IMPORTANCE

β-Lactam antibiotics are among the safest and most effective antibiotics. Many patients report allergies to these drugs that limit their use, resulting in the use of broad-spectrum antibiotics that increase the risk for antimicrobial resistance and adverse events.

OBSERVATIONS

Approximately 10% of the US population has reported allergies to the β-lactam agent penicillin, with higher rates reported by older and hospitalized patients. Although many patients report that they are allergic to penicillin, clinically significant IgE-mediated or T lymphocyte-mediated penicillin hypersensitivity is uncommon (<5%). Currently, the rate of IgE-mediated penicillin allergies is decreasing, potentially due to a decreased use of parenteral penicillins, and because severe anaphylactic reactions to oral amoxicillin are rare. IgE-mediated penicillin allergy wanes over time, with 80% of patients becoming tolerant after a decade. Cross-reactivity between penicillin and cephalosporin drugs occurs in about 2% of cases, less than the 8% reported previously. Some patients have a medical history that suggests they are at a low risk for developing an allergic reaction to penicillin. Low-risk histories include patients having isolated nonallergic symptoms, such as gastrointestinal symptoms, or patients solely with a family history of a penicillin allergy, symptoms of pruritus without rash, or remote (>10 years) unknown reactions without features suggestive of an IgE-mediated reaction. A moderate-risk history includes urticaria or other pruritic rashes and reactions with features of IgE-mediated reactions. A high-risk history includes patients who have had anaphylaxis, positive penicillin skin testing, recurrent penicillin reactions, or hypersensitivities to multiple β-lactam antibiotics. The goals of antimicrobial stewardship are undermined when reported allergy to penicillin leads to the use of broad-spectrum antibiotics that increase the risk for antimicrobial resistance, including increased risk of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. Broad-spectrum antimicrobial agents also increase the risk of developing Clostridium difficile (also known as Clostridioides difficile) infection. Direct amoxicillin challenge is appropriate for patients with low-risk allergy histories. Moderate-risk patients can be evaluated with penicillin skin testing, which carries a negative predictive value that exceeds 95% and approaches 100% when combined with amoxicillin challenge. Clinicians performing penicillin allergy evaluation need to identify what methods are supported by their available resources.

CONCLUSIONS AND RELEVANCE

Many patients report they are allergic to penicillin but few have clinically significant reactions. Evaluation of penicillin allergy before deciding not to use penicillin or other β-lactam antibiotics is an important tool for antimicrobial stewardship.

Antibiotic allergy

Antibiotics are the commonest cause of life-threatening immune-mediated drug reactions that are considered off-target, including anaphylaxis, and organ-specific and severe cutaneous adverse reactions. However, many antibiotic reactions documented as allergies were unknown or not remembered by the patient, cutaneous reactions unrelated to drug hypersensitivity, drug-infection interactions, or drug intolerances. Although such reactions pose negligible risk to patients, they currently represent a global threat to public health. Antibiotic allergy labels result in displacement of first-line therapies for antibiotic prophylaxis and treatment. A penicillin allergy label, in particular, is associated with increased use of broad-spectrum and non-β-lactam antibiotics, which results in increased adverse events and antibiotic resistance. Most patients labelled as allergic to penicillins are not allergic when appropriately stratified for risk, tested, and re-challenged. Given the public health importance of penicillin allergy, this Review provides a global update on antibiotic allergy epidemiology, classification, mechanisms, and management.

Antibiotic allergy labels in hospitalized and critically ill adults: A review of current impacts of inaccurate labelling

Antibiotic allergy labels (AALs) are reported by approximately 20% of hospitalized patients, yet over 85% will be negative on formal allergy testing. Hospitalized patients with an AAL have inferior patient outcomes, increased colonization with multidrug-resistant organisms and frequently receive inappropriate antimicrobials. Hospitalized populations have been well studied but, to date, the impact of AALs on patients with critical illness remains less well defined. We review the prevalence and impact of AALs on hospitalized patients, including those in in critical care.

Strategies for Antimicrobial Stewardship in Solid Organ Transplant Recipients

Complications of antimicrobial therapy, such as multidrug-resistant organisms and Clostridium difficile, commonly affect solid-organ transplant recipients and have been associated with graft loss and mortality. Although opportunities are abundant, antimicrobial stewardship practices guiding appropriate therapy have been infrequently reported in transplant patients. A patient-centered, multidisciplinary structure, using established antimicrobial optimization principles, is needed to create nuanced approaches to protect patients and antimicrobials and improve outcomes.

The Safety and Efficacy of an Oral Penicillin Challenge Program in Cancer Patients: A Multicenter Pilot Study

Antibiotic allergies are reported by up to 1 in 4 cancer patients, almost 50% of which are considered low risk and precede the cancer diagnosis. We demonstrate the successful and safe implementation of a pilot oral penicillin challenge program for cancer patients with low-risk penicillin allergies, increasing the use of penicillin and narrow-spectrum beta-lactams post-testing.

Appropriateness of Beta-Lactam Allergy Record Updates After an Allergy Service Consult

BACKGROUND

Many patients with a self-reported penicillin allergy go on to tolerate beta-lactam antibiotics. Allergy specialists may be consulted to determine the nature and extent of the allergy. However, electronic allergy records must be appropriately updated such that recommendations are carried forward.

OBJECTIVE

To determine the percentage of patients who have their electronic allergy record updated after an allergy service consult (ASC).

METHODS

This was a retrospective study of patients with at least 1 documented beta-lactam allergy and had an ASC during (inpatient) or prior to (outpatient) hospital admission at Northwestern Memorial Hospital and Prentice Women's Hospital in Chicago, Illinois.

RESULTS

Within the study period, a total of 26 526 patients were identified as having a documented antibiotic allergy, with 21 657 patients (81.6% of patients with allergies) having a listed beta-lactam allergy. Of these patients, 1689 (7.8%) patients were identified as having an ASC during or prior to admission, with 598 patients meeting inclusion criteria. Changes in the allergy record were recommended by the ASC for 62% (n = 371) of patients; however, the allergy record was updated after the ASC in 74.9% (n = 278) of patients.

CONCLUSION

ASC recommendations to delabel a patient as beta-lactam allergic must result in updating the allergy record in order to optimize future treatment. Given the low proportion of allergy-labeled patients tested, programs outside formal ASCs should be considered.

Hospitalizations in Children with a Penicillin Allergy Label: An Assessment of Healthcare Impact

BACKGROUND

Beta-lactam allergy is overdiagnosed. Diagnosis of penicillin allergy has been associated with a greater use of hospital resources and an increased risk of antibiotic-resistant infections, although this issue remains poorly studied in children. We aimed to compare patient characteristics and use of hospital resources in hospitalized children with and without a record of penicillin allergy.

METHODS

We identified all hospitalizations in children labelled as being allergic to penicillin in a database containing all hospitalizations in Portuguese public hospitals between 2000 and 2014, and compared these with a similar number of age-, sex-, and main diagnosis-matched hospitalizations without a penicillin allergy label. Comparisons were made for length of hospital stay, comorbidities (Charlson Comorbidity Index), in-hospital mortality, and hospitalization costs.

RESULTS

We identified 1,718 hospitalizations corresponding to children labelled as penicillin-allergic. Compared with patients without such a label, these children had longer hospital stays (mean 5 vs. 4 days, p = 0.03) and a higher comorbidity index (mean 0.11 vs. 0.09, p < 0.001). Hospitalization costs were also higher (EUR 2,071 vs. 1,798), but the difference was not significant (p = 0.12).

CONCLUSIONS

Hospitalizations of children labelled as allergic to penicillin are associated with longer hospital stays, more comorbidities, and a tendency towards higher hospitalization costs. An accurate diagnosis of penicillin allergy based on clinical history and confirmatory tests is therefore essential in all paediatric patients.

The Use of Telemedicine for Penicillin Allergy Skin Testing

BACKGROUND

Penicillin skin testing (PST) is increasingly used as a tool to evaluate penicillin allergy in patients with a reported history. The limited availability of allergists, however, may be an impeding factor.

OBJECTIVE

We sought to assess the clinical utility of telemedicine to facilitate PST.

METHODS

Penicillin-allergic inpatients receiving systemic antibiotics were prospectively identified between April and August 2017. Qualifying patients underwent PST performed by a trained allergy/immunology physician assistant (PA). On completion of PST, a telemedicine consultation, through the use of real-time interactive video conferencing (Microsoft Lync 2013, Redmond, Wash), was performed remotely by an allergist. Patients were surveyed regarding their satisfaction with the telemedicine experience.

RESULTS

Fifty patients consented to PST through a telemedicine consultation. The average total time to complete a consultation was 128 minutes (standard deviation [SD] ± 33). Of this, the average PA travel time was 46 minutes (36%) with the remaining time spent on clinical services (82 minutes, 64%). The average physician telemedicine time per patient was 5 minutes (SD ± 2). Patients rated their experience as an average of 4.5 on a scale of 1 (highly unsatisfied) to 5 (highly satisfied). Of the 46 PST-negative patients, 33 were transitioned to a β-lactam antibiotic that reduced the use of vancomycin, metronidazole, aztreonam, aminoglycosides, and clindamycin (P < .05). More than $30,000 was saved throughout the study period.

CONCLUSIONS

Telemedicine is an effective and novel approach to facilitate PST in the inpatient setting and carries a high degree of patient satisfaction. This method has the potential to optimize and improve access to allergy/immunology resources.

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.

Optimizing preoperative prophylaxis in patients with reported β-lactam allergy: a novel extension of antimicrobial stewardship

Background

Use of alternative second-line antibiotics is associated with adverse events in patients reporting β-lactam allergy. In the perioperative setting, we hypothesized that structured allergy histories, without the use of skin testing, can reduce alternative prophylactic antibiotic use.

Objectives

Assess the impact of structured allergy histories on patients with self-reported β-lactam allergy (SRBA) undergoing elective surgical procedures.

Methods

Structured allergy histories were performed by a pharmacist and reviewed with an infectious diseases physician. Patients were deemed safe to proceed with cefazolin prophylaxis if they did not describe a history of type I-mediated or severe reaction. Antibiotic prophylaxis orders (with approval by the surgical team) were scheduled into the computerized order entry system to be given prior to first incision of the operation.

Results

Of the 485 patients with SRBA that underwent structured allergy histories, 117 (24.1%) reported a type I-mediated allergy history; 267 (55.1%) patients received cefazolin prophylaxis and none subsequently experienced an adverse reaction. After intervention implementation, the overall use of alternative antibiotic prophylaxis at Michael Garron Hospital (Toronto, Canada) among those with SRBA decreased from 81.9% to 55.9%. This drop was associated with the number of monthly assessments (P < 0.001) in a regression analysis.

Conclusions

Using a simple structured history and the principles of prospective audit and feedback, we were able to increase the use of cefazolin perioperative prophylaxis without any serious adverse events and in the absence of skin testing or diagnostic challenges.

Antibiotic Allergy in Pediatrics

The overlabeling of pediatric antibiotic allergy represents a huge burden in society. Given that up to 10% of the US population is labeled as penicillin allergic, it can be estimated that at least 5 million children in this country are labeled with penicillin allergy. We now understand that most of the cutaneous symptoms that are interpreted as drug allergy are likely viral induced or due to a drug-virus interaction, and they usually do not represent a long-lasting, drug-specific, adaptive immune response to the antibiotic that a child received. Because most antibiotic allergy labels acquired in childhood are carried into adulthood, the overlabeling of antibiotic allergy is a liability that leads to unnecessary long-term health care risks, costs, and antibiotic resistance. Fortunately, awareness of this growing burden is increasing and leading to more emphasis on antibiotic allergy delabeling strategies in the adult population. There is growing literature that is used to support the safe and efficacious use of tools such as skin testing and drug challenge to evaluate and manage children with antibiotic allergy labels. In addition, there is an increasing understanding of antibiotic reactivity within classes and side-chain reactions. In summary, a better overall understanding of the current tools available for the diagnosis and management of adverse drug reactions is likely to change how pediatric primary care providers evaluate and treat patients with such diagnoses and prevent the unnecessary avoidance of antibiotics, particularly penicillins.

Addressing Inpatient Beta-Lactam Allergies: A Multihospital Implementation

Addressing inaccurate penicillin allergies is encouraged as part of antibiotic stewardship in the inpatient setting. However, implementing interventions targeted at the 10% to 15% of inpatients reporting a previous penicillin allergy can pose substantial logistic challenges. We implemented a computerized guideline for patients with reported beta-lactam allergy at 5 hospitals within a single health care system in the Boston area. In this article, we describe our implementation roadmap, including both successes achieved and challenges faced. We explain key implementation steps, including assembling a team, stakeholder engagement, developing or selecting an approach, spreading the change, establishing measures, and measuring impact. The objective was to detail the lessons learned while empowering others to be part of this important, multidisciplinary work to improve the care of patients with reported beta-lactam allergies.

The Cost of Self-Reported Penicillin Allergy: A Systematic Review

BACKGROUND

Patients who report a penicillin (PCN) allergy receive suboptimal antibiotic therapy compared with patients not reporting an allergy. However, a majority of patients who report PCN allergy are not truly allergic on confirmatory testing. Ruling out PCN allergy by testing may improve clinical and economic outcomes for patients with reported allergies requiring antibiotic therapy.

OBJECTIVE

The objective of this study was to summarize clinical and economic outcomes associated with PCN allergy and provide recommendations for future cost-effectiveness analyses for PCN allergy testing.

METHODS

A literature search was conducted using SCOPUS, EMBASE, and PubMed, including all articles published any date through April 25, 2017 (PROSPERO Registration number 42017064112). A total of 1518 abstracts were found during the initial search with 96 duplicates, for a total of 1422 articles for screening. Thirty articles were included for qualitative synthesis and full data extraction.

RESULTS

The majority of the studies included had an observational design focusing on inpatient admissions. The most frequently measured outcome in the context of PCN allergy was optimizing antibiotic therapy. Patients with PCN allergy were found to have direct drug costs during inpatient admission ranging from no difference to an additional $609/patient compared with patients without PCN allergy. Outpatient prescription costs were estimated from $14 to $193/patient higher for PCN allergic patients. Total inpatient costs were less for patients without PCN allergy with average savings from $1145 to $4254/patient.

CONCLUSIONS

Evaluations of clinical and economic outcomes of PCN allergy are primarily observational and focus on inpatient populations. Long-term relationships between PCN allergy and clinical and economic outcomes are unknown.

Confronting the Challenge of Beta-Lactam Allergies: A Quasi-Experimental Study Assessing Impact of Pharmacy-Led Interventions

OBJECTIVE

To improve allergy history documentation and increase the use of beta-lactams when appropriate in patients with a reported beta-lactam allergy.

METHODS

This pre-post study was conducted at a 167-bed tertiary care community hospital and evaluated multidisciplinary interventions on allergy documentation and antibiotic selection. Interventions included education, creation of local practice guidelines, and modified practices for pharmacists and pharmacy technicians. Inpatients with a reported beta-lactam allergy receiving at least 1 antibiotic for >24 hours were included; first admissions were assessed. Primary outcomes were documentation of reaction type and percentage of patients receiving non-beta-lactam therapy. Secondary outcomes included documentation of previously tolerated beta-lactams, modification of non-beta-lactam therapy, discharge antibiotics, and adverse reactions.

RESULTS

A total of 179 patients were included, 91 preintervention and 88 postintervention. No significant differences were observed between the before versus after groups in the percentage of patients with documentation of reaction type (90.1% vs 89.8%, P = .940) or the overall percentage of patients receiving non-beta-lactams (86.8% vs 84.1%, P = .605). However, significantly more patients in the after phase had documentation of previously tolerated beta-lactams (8.8% vs 28.4%, P = .001), and among patients receiving a non-beta-lactam, a greater percentage was subsequently switched to a beta-lactam (11.4% vs 25.7%, P = .022). One allergic reaction was documented during the study, which occurred in the before phase.

CONCLUSION

Multidisciplinary education and local guideline implementation led by pharmacists may improve allergy documentation and antibiotic selection in patients with reported beta-lactam allergies.

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.

The Cost of Penicillin Allergy Evaluation

BACKGROUND

Unverified penicillin allergy leads to adverse downstream clinical and economic sequelae. Penicillin allergy evaluation can be used to identify true, IgE-mediated allergy.

OBJECTIVE

To estimate the cost of penicillin allergy evaluation using time-driven activity-based costing (TDABC).

METHODS

We implemented TDABC throughout the care pathway for 30 outpatients presenting for penicillin allergy evaluation. The base-case evaluation included penicillin skin testing and a 1-step amoxicillin drug challenge, performed by an allergist. We varied assumptions about the provider type, clinical setting, procedure type, and personnel timing.

RESULTS

The base-case penicillin allergy evaluation costs $220 in 2016 US dollars: $98 for personnel, $119 for consumables, and $3 for space. In sensitivity analyses, lower cost estimates were achieved when only a drug challenge was performed (ie, no skin test, $84) and a nurse practitioner provider was used ($170). Adjusting for the probability of anaphylaxis did not result in a changed estimate ($220); although other analyses led to modest changes in the TDABC estimate ($214-$246), higher estimates were identified with changing to a low-demand practice setting ($268), a 50% increase in personnel times ($269), and including clinician documentation time ($288). In a least/most costly scenario analyses, the lowest TDABC estimate was $40 and the highest was $537.

CONCLUSIONS

Using TDABC, penicillin allergy evaluation costs $220; even with varied assumptions adjusting for operational challenges, clinical setting, and expanded testing, penicillin allergy evaluation still costs only about $540. This modest investment may be offset for patients treated with costly alternative antibiotics that also may result in adverse consequences.

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.

The intensive care medicine research agenda on multidrug-resistant bacteria, antibiotics, and stewardship

PURPOSE

To concisely describe the current standards of care, major recent advances, common beliefs that have been contradicted by recent trials, areas of uncertainty, and clinical studies that need to be performed over the next decade and their expected outcomes with regard to the management of multidrug-resistant (MDR) bacteria, antibiotic use, and antimicrobial stewardship in the intensive care unit (ICU) setting.

METHODS

Narrative review based on a systematic analysis of the medical literature, national and international guidelines, and expert opinion.

RESULTS

The prevalence of infection of critically ill patients by MDR bacteria is rapidly evolving. Clinical studies aimed at improving understanding of the changing patterns of these infections in ICUs are urgently needed. Ideal antibiotic utilization is another area of uncertainty requiring additional investigations aimed at better understanding of dose optimization, duration of therapy, use of combination treatment, aerosolized antibiotics, and the integration of rapid diagnostics as a guide for treatment. Moreover, there is an imperative need to develop non-antibiotic approaches for the prevention and treatment of MDR infections in the ICU. Finally, clinical research aimed at demonstrating the beneficial impact of antimicrobial stewardship in the ICU setting is essential.

CONCLUSIONS

These and other fundamental questions need to be addressed over the next decade in order to better understand how to prevent, diagnose, and treat MDR bacterial infections. Clinical studies described in this research agenda provide a template and set priorities for investigations that should be performed in this field.

Significant Publications on Infectious Diseases Pharmacotherapy in 2016

PURPOSE

This is a summary of the most important articles on infectious diseases (ID) pharmacotherapy published in peer-reviewed literature in 2016 as selected by clinical pharmacists with ID expertise.

SUMMARY

The Houston Infectious Diseases Network (HIDN) was asked to identify articles published in peer-reviewed literature in 2016 that were believed to contribute significantly to ID pharmacotherapy, including human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS). A list of 46 articles on general ID pharmacotherapy and 8 articles on HIV/AIDS were nominated. Members of the Society of Infectious Diseases Pharmacists (SIDP) were surveyed to select 10 general ID articles believed to have made a significant impact on general ID pharmacotherapy and 1 article most significant to HIV/AIDS pharmacotherapy. Of 445 SIDP members surveyed, 212 (47.6%) and 95 (21.3%) members voted for general ID pharmacotherapy- and HIV/AIDS-related articles, respectively. The 11 highest-ranked papers (10 general ID-related articles and 1 HIV/AIDS-related article) are summarized here.

CONCLUSION

With the large number of ID-related articles published each year, it can be challenging to stay current with the most relevant ID publications. This review of significant publications in 2016 may provide a starting point for that process.

Antimicrobial Stewardship Approaches in the Intensive Care Unit

Antimicrobial stewardship programs aim to monitor, improve, and measure responsible antibiotic use. The intensive care unit (ICU), with its critically ill patients and prevalence of multiple drug-resistant pathogens, presents unique challenges. This article reviews approaches to stewardship with application to the ICU, including the value of diagnostics, principles of empirical and definitive therapy, and measures of effectiveness. There is good evidence that antimicrobial stewardship results in more appropriate antimicrobial use, shorter therapy durations, and lower resistance rates. Data demonstrating hard clinical outcomes, such as adverse events and mortality, are more limited but encouraging; further studies are needed.

Impact of an Integrated Antibiotic Allergy Testing Program on Antimicrobial Stewardship: A Multicenter Evaluation

Background

Despite the high prevalence of patient-reported antibiotic allergy (so-called antibiotic allergy labels [AALs]) and their impact on antibiotic prescribing, incorporation of antibiotic allergy testing (AAT) into antimicrobial stewardship (AMS) programs (AAT-AMS) is not widespread. We aimed to evaluate the impact of an AAT-AMS program on AAL prevalence, antibiotic usage, and appropriateness of prescribing.

Methods

AAT-AMS was implemented at two large Australian hospitals during a 14-month period beginning May 2015. Baseline demographics, AAL history, age-adjusted Charlson comorbidity index, infection history, and antibiotic usage for 12 months prior to testing (pre-AAT-AMS) and 3 months following testing (post-AAT-AMS) were recorded for each participant. Study outcomes included the proportion of patients who were "de-labeled" of their AAL, spectrum of antibiotic courses pre- and post-AAT-AMS, and antibiotic appropriateness (using standard definitions).

Results

From the 118 antibiotic allergy-tested patients, 226 AALs were reported (mean, 1.91/patient), with 53.6% involving 1 or more penicillin class drug. AAT-AMS allowed AAL de-labeling in 98 (83%) patients-56% (55/98) with all AALs removed. Post-AAT, prescribing of narrow-spectrum penicillins was more likely (adjusted odds ratio [aOR], 2.81, 95% confidence interval [CI], 1.45-5.42), as was narrow-spectrum β-lactams (aOR, 3.54; 95% CI, 1.98-6.33), and appropriate antibiotics (aOR, 12.27; 95% CI, 5.00-30.09); and less likely for restricted antibiotics (aOR, 0.16; 95% CI, .09-.29), after adjusting for indication, Charlson comorbidity index, and care setting.

Conclusions

An integrated AAT-AMS program was effective in both de-labeling of AALs and promotion of improved antibiotic usage and appropriateness, supporting the routine incorporation of AAT into AMS programs.

A survey of inpatient practitioner knowledge of penicillin allergy at 2 community teaching hospitals

BACKGROUND

The negative effect of the penicillin allergy label on antibiotic use and patient outcomes has brought to light the need for thorough penicillin allergy assessments and heightened practitioner education.

OBJECTIVE

To evaluate practitioner knowledge of penicillin allergy and the clinical approach to the patients with penicillin allergy.

METHODS

An electronic survey was distributed to attending physicians, residents, pharmacists, nurse practitioners, and physician assistants practicing adult inpatient medicine at 2 community-based teaching hospitals from February to April 2016.

RESULTS

A total of 276 (39%) of 716 practitioners completed surveys were analyzed. Most respondents were attending physicians (45%) with more than 10 years of experience (53%). Approximately half of the respondents indicated that they were unfamiliar with the rate of cross-reactivity between penicillin and cephalosporin (46%), carbapenem (42%), and monobactam (48%) antibiotics. When evaluating the role of penicillin skin testing and temporary induction of drug tolerance in the case vignettes, only 41% and 19% of respondents appropriately considered these options as the leading antibiotic management plan, respectively. Despite acknowledging the need for allergy/immunology consultation in clinical scenarios, 86% of respondents indicated that they never consult an allergist or immunologist or do so only once per year. Overall, pharmacists had a better understanding of the natural history of penicillin allergy and antibiotic cross-reactivity (P < .05).

CONCLUSION

There is an overall limited understanding of the management of patients with a history of penicillin allergy in the hospital setting, where collaborative efforts between allergy and nonallergy health care practitioners are sparse. The expansion of a multidisciplinary approach may optimize antimicrobial prescribing in this subset of patients.

Tackling inpatient penicillin allergies: Assessing tools for antimicrobial stewardship

BACKGROUND

Reported penicillin allergy rarely reflects penicillin intolerance. Failure to address inpatient penicillin allergies results in more broad-spectrum antibiotic use, treatment failures, and adverse drug events.

OBJECTIVE

We aimed to determine the optimal approach to penicillin allergies among medical inpatients.

METHODS

We evaluated internal medicine inpatients reporting penicillin allergy in 3 periods: (1) standard of care (SOC), (2) penicillin skin testing (ST), and (3) computerized guideline application with decision support (APP). The primary outcome was use of a penicillin or cephalosporin, comparing interventions to SOC using multivariable logistic regression.

RESULTS

There were 625 patients: SOC, 148; ST, 278; and APP, 199. Of 278 ST patients, 179 (64%) were skin test eligible; 43 (24%) received testing and none were allergic. In the APP period, there were 292 unique Web site views; 112 users (38%) completed clinical decision support. Although ST period patients did not have increased odds of penicillin or cephalosporin use overall (adjusted odds ratio [aOR] 1.3; 95% CI, 0.8-2.0), we observed significant increased odds of penicillin or cephalosporin use overall in the APP period (aOR, 1.8; 95% CI, 1.1-2.9) and in a per-protocol analysis of the skin tested subset (aOR, 5.7; 95% CI, 2.6-12.5).

CONCLUSIONS

Both APP and ST-when completed-increased the use of penicillin and cephalosporin antibiotics among inpatients reporting penicillin allergy. While the skin tested subset showed an almost 6-fold impact, the computerized guideline significantly increased penicillin or cephalosporin use overall nearly 2-fold and was readily implemented.

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.