Penicillin and Beta-Lactam Hypersensitivity

Urticaria-Like Hypersensitivity Reaction Following Botulinum Toxin Injection: A Case Report of Possible Interaction with β-Lactam Antibiotics

Botulinum toxin serotype A (BTX-A) is commonly used for treating facial dynamic wrinkles. The clinical safety of BTX-A has been proven, and it has few side effects; despite this, BTX-A has the potential to cause an allergic reaction. This case raises concerns about a possible interaction between botulinum toxin serotype A (CBTX-A) and β-lactam antibiotics, contributing to the limited literature on hypersensitivity reactions. Herein, we described the case of a 35-year-old woman who was injected with Chinese botulinum toxin serotype A (CBTX-A) to treat crow's feet. The treatment was performed after the patient had taken cefprozil for an upper respiratory tract infection. Subsequently, the patient developed urticaria-like symptoms that completely resolved within 24 hours after administration of antihistamines. This case emphasises the need for careful medication history review before botulinum toxin administration, especially in patients receiving β-lactam antibiotics, as hypersensitivity reactions may occur.

Patterns of antimicrobial use among hospitalized Veterans with and without a penicillin-class allergy

Objective

To explore the progress that the Veterans Health Administration has made to minimize the impact of the penicillin (PCN) allergy label, we determined the proportion of Veterans who reported a PCN-class allergy at the time of hospitalization and described antibiotic use in hospitalizations with and without a PCN-class allergy.

Design

Cross-sectional study.

Participants

National sample of 6,541,299 acute care admissions between 2011 and 2022.

Methods

We calculated the prevalence of PCN-class allergies on admission and used Poisson regression to compare patterns of antibiotic use between hospitalizations with and without a PCN-class allergy.

Results

The prevalence of PCN-class allergies on admission decreased from 12.99% to 11.20%. Use of cefazolin and non-pseudomonal third-generation cephalosporins increased regardless of PCN-class allergy status ("PCN-class allergy only" +11.46%, "No antibiotic allergy" +4.92%). The prevalence ratio (PR) for antibiotic use in hospitalizations with a PCN-class allergy compared to hospitalizations without antibiotic allergies, decreased for anti-Methicillin Resistant Staphylococcus aureus agents (1.26 [1.25, 1.28] to 1.15 [1.13, 1.17]), carbapenems (1.59 [1.54, 1.65] to 1.47 [1.41, 1.53]), and aztreonam (23.89 [22.45, 25.43] to 17.57 [15.90, 19.42]); and increased for fluoroquinolones (1.58 [1.56, 1.60] to 2.15 [2.09, 2.20]).

Conclusions

Prevalence of PCN-class allergies is declining and narrow-spectrum βL use is rising among hospitalized Veterans. Prescribing differences are decreasing between hospitalizations with and without a reported PCN-class allergy, except for aminoglycosides, clindamycin, and fluoroquinolones. These findings can serve to identify areas of focus for future analyses or interventions related to the impact of the PCN allergy label on antibiotic selection.

Removing penicillin allergy label in a hospitalized adolescent with a remote penicillin and recent cephalosporin allergy

Background: β-Lactam antibiotics are widely used with increased utilization in hospitalized patients. Of this population, as high as 10-20% report an allergy to β-lactam antibiotics but <5% are at risk of developing clinically significant immunoglobulin E- or T-lymphocyte-mediated reactions. Most of the time, these reported allergies are present during an illness with no previous inquiry of their validity, which makes investigation and possible removal of this allergy label a challenge. Methods: We report a 16-year-old boy who presented with 1 week of night sweats, chills, headaches, and fatigue, followed by 1 day of fever and right knee swelling and who was diagnosed with septic bursitis. Due to concern of a penicillin allergy label, the patient was started on a cefepime infusion. Five minutes into the infusion, the patient reported puffy eyes and itchy throat, followed by a witnessed cascading flat nonpruritic erythematous rash from head to shoulders. This rash went away in 3 minutes after stopping the infusion and the patient being given 50 mg of intravenous diphenhydramine and 10 mg of oral dexamethasone. He was subsequently diagnosed with a cefepime allergy. Results: Allergy/immunology was the speciality consulted, and, by using a screening questionnaire, the patient's reported penicillin allergy was determined to be low risk. Subsequent 1-step oral challenge was the key to providing the patient with the necessary antibiotic course to resolve his infection. Conclusion: Multiple reported antibiotic allergies lead to poor antibiotic stewardship that causes impactful health and financial burden on the patient and health-care system. It is thus important to have an evidence-based systematic approach to de-label penicillin antibiotic allergy labels to reduce these potential harms.

Diagnosis and selection of alternative antibiotics in beta-lactams hypersensitivity reactions: Current recommendations and challenges

Beta-lactam (BLM) antibiotics, including amino-penicillin and cephalosporins, are typically the first-choice treatment for bacterial infections. However, adverse reactions to these antibiotics are frequently reported, causing non-allergist physicians to select alternative broad-spectrum antibiotics that can have harmful consequences. Patients with unclear histories of hypersensitivity reactions to BLMs should undergo an allergy workup to establish a firm diagnosis, particularly when different drugs are prescribed simultaneously. However, finding the safest, most precise, and cost-effective methods for confirming BLMs hypersensitivity and selecting the most appropriate alternative BLM is uncertain, particularly in severe delayed reactions. This review aims to provide data and recommendations on the availability and validity of skin tests (STs), drug provocation test (DPT) protocols, based on the latest published literature and guideline. To make the process more practical, we focused on cross-reactivity between BLMs and diagnostic tests. There are two main novel aspects of this document: 1) For T-cell-mediated reactions, patient stratification into high, moderate, and low-risk groups based on the mortality and morbidity of adverse drug reactions. 2) For IgE-mediated reactions, stratification of individuals with isolated limited urticarial without anaphylaxis in a low-risk group and removal of the extensive limitation.

Administration of β-lactam antibiotics to patients with reported penicillin allergy in the emergency department

BACKGROUND

β-lactam antibiotics are amongst the most commonly prescribed medications in the Emergency Department (ED) due to their role in empiric sepsis therapy; however, inferior therapeutic options are often utilized due to a reported allergy; penicillin (PCN) being most frequent. In the United States, 10% of the population endorses an allergic reaction to PCN while <1% experience IgE-mediated reactions. This study aimed to evaluate the frequency and outcome of patients in the ED whose PCN allergies were challenged with β-lactam antibiotics.

METHODS

We conducted a retrospective chart review of patients in the ED at an academic medical center aged ≥18, and who received a β-lactam despite a reported PCN allergy between January 2015 and December 2019. Patients who did not receive a β-lactam or did not report a PCN allergy prior to administration were excluded. The primary outcome was the frequency of IgE-mediated reactions in response to β-lactam administration. A secondary outcome assessed the frequency of continuation of β-lactams upon admission from the ED.

RESULTS

819 patients were included (66% female) with prior reported PCN reactions: hives (22.5%), rash (15.4%), swelling (6.2%), anaphylaxis (3.5%), other (12.1%), or undocumented on medical electronic record (40.3%). No patients experienced an IgE-mediated reaction to the β-lactam administered in the ED. Previously reported allergies had no effect on the continuation of β-lactams when admitted or discharged (OR: 1, 95% CI: 0.7-1.44). Patients who had a history of an IgE-mediated penicillin allergy were frequently continued (77%) on a β-lactam after leaving the ED via admission or discharge.

CONCLUSION

β-lactam administration in patients with previously reported PCN allergies did not result in any IgE-mediated reactions nor in an increase in adverse reactions. Our data contributes to the body of evidence that supports the administration of β-lactams to patients with documented PCN allergies.

Deep cervical abscesses in children: efficacy of the cefotaxime-rifampicin combination

The objective is to determine whether a medical treatment, the combination of cefotaxime and rifampicin, is effective in avoiding surgery for managing deep cervical abscesses in children and to determine prognostic factors in the efficacy of this medical treatment. This is a retrospective analysis of all patients under 18 presenting with para- or retro-pharyngeal abscess over the period 2010-2020 in two hospitals' pediatric otorhinolaryngology departments. One hundred six records were included. Multivariate analyses were performed to study the relationship between the prescription of the Cefotaxime-rifampicin protocol at the onset of the management and the use of surgery and to evaluate the prognostic factors of its efficacy. The 53 patients who received the cefotaxime-rifampicin protocol as first-line treatment (vs. 53 patients receiving a different protocol) required surgery less frequently: 7.5% versus 32.1%, validated by a Kaplan-Meier survival curve and a Cox model analysis adjusted for age and abscess size (Hazard Ratio = 0.21). This good outcome of the cefotaxime-rifampicin protocol was not demonstrated when it was instituted as a second-line treatment after the failure of a different protocol. An abscess larger than 32 mm at hospitalization was significantly associated with more frequent use of surgery in multivariate analysis adjusted for age and sex (Hazard Ratio = 8.5).    Conclusions: The cefotaxime-rifampicin protocol appears to be an effective first-line treatment in managing non-complicated deep cervical abscesses in children. What is Known: • Nowadays, medical treatment is preferred for managing deep neck abscesses in children. There has yet to be a consensus on the antibiotic therapy to be proposed. • Staphylococcus aureus and streptococci are the most frequent causative organisms. What is New: • The cefotaxime-rifampicin protocol introduced at first intention is effective, with only 7.5% of patients requiring drainage surgery. • The only risk factor for failure of the medical treatment is the initial size of the abscess.

Documented Penicillin Allergies Should Not Preclude Use of Preoperative Cefazolin in Hip and Knee Arthroplasty

INTRODUCTION

Perioperative cefazolin administration for total joint arthroplasty is a first-line antibiotic recommended by the American Academy of Orthopaedic Surgeons (AAOS) guidelines for the prevention of periprosthetic joint infections (PJIs). We aim to analyze the clinical viability of giving patients with a documented penicillin allergy (PA) a perioperative full-strength cefazolin "test dose" under anesthesia.

METHODS

This is a retrospective chart review of 2,451 total joint arthroplasties from a high-volume arthroplasty orthopaedic surgeon over a 5-year period from January 2013 through December 2017. This surgeon routinely gave patients with a documented PA a full-strength cefazolin test dose while under anesthesia instead of administrating a second-line antibiotic. The primary outcomes examined were allergic reaction and postoperative infection.

RESULTS

Cefazolin was given to 87.1% of all patients (1,990) and 46.0% of patients with a PA (143). The total rate of allergic reactions among all patients was 0.5% (11). Only one patient with a documented PA who received cefazolin had an allergic reaction. The reaction was not severe and did not require any additional treatment. In patients who had no reported allergies and received cefazolin, 0.3% (6) had an allergic reaction. There was no statistically significant difference in the rate of allergic reaction when comparing patients with and without a PA (P = 0.95). Patients receiving cefazolin had an overall PJI rate of 2.9% (57) versus those patients receiving antibiotics other than cefazolin who sustained a 5.5% PJI rate (16), which was statistically significant (P = 0.02).

CONCLUSION

This study found that utilization of a full-strength test dose of cefazolin in patients with a documented PA is a feasible, safe, and effective way of increasing the rate of cefazolin administration and thus mitigating the risk of PJIs.

Antibiotic oral provocation challenge in children

AIM

The main objective of this study was to see how many of the children, with a suspected antibiotic allergy, developed an allergic or adverse reaction to a drug provocation test.

METHODS

Data on children that had undergone a drug provocation test for a suspected antibiotic allergy were compiled retrospectively for the period from 2007-2018. The median age at the first provocation was 2.25 years (1.5-5.7). Standardised questionnaires, the children's parents had answered before the provocation, were used to evaluate the originally suspected allergic reaction, previous health, atopic diseases and family history.

RESULTS

Ninety-two (6.4%) of the 1440 children showed a possible mild allergic reaction. Sixty-four of the 92 children underwent a second drug provocation test 1-2 years later. At that time, only eleven developed a positive- or a possible-delayed reaction.

CONCLUSION

An immediate moderate or severe allergic reaction was excluded in all cases of suspected antibiotic allergy in this study. Our study indicates that an oral drug provocation test is safe. It may be appropriate to wait for 6 months or more after the initial event of ADR before these tests are performed. A second oral provocation 1-2 years after the first one shows that ADRs are outgrown in most children.

Outcomes in hospitalised patients with sepsis, severe sepsis or septic shock and reported penicillin allergy: a retrospective cohort study

OBJECTIVE

To determine outcomes in hospitalised patients with sepsis and reported penicillin allergy (PcnA).

DESIGN

Observational retrospective cohort study using data from electronic health records.

SETTING

A large single health system with 11 hospitals of small, medium and large sizes including a 630-bed tertiary care teaching hospital.

PARTICIPANTS

Patients (n=5238) ≥18 years of age, hospitalised with sepsis, severe sepsis or septic shock between 1 January 2016 and 31 December 2018, received antibacterial agents, and had documented PcnA status. Patients <18 years of age at admission were excluded.

OUTCOME MEASURES

Primary outcomes evaluated were inpatient mortality and 30-day mortality posthospital discharge. Secondary outcomes were hospital length of stay, 30-day readmissions, duration of antibiotic use, rate of Clostridium difficile infection and total cost of care.

RESULTS

There was no difference in outcomes including inpatient or 30-day mortality, hospital length of stay, in-hospital antibiotic duration, C. difficile infection, total cost of care and 30-day readmission rate between patients labelled with a PcnA vs patients who did not report PcnA (non-PcnA).

CONCLUSION

In this retrospective single health system study, there was no difference in key outcomes including inpatient or 30-day mortality in patients admitted with sepsis and reported PcnA compared with patients who reported no PcnA.

Reactions of cisplatin and oxaliplatin with penicillin G: implications for drug inactivation and biological activity

Determination of the toxicity of compounds toward cancer cells is a frequent procedure in drug discovery. For metal complexes, which are often reactive prodrugs, care has to be taken to consider reactions with components of the cell culture medium that might change the speciation of the metal complex before it is taken up by the cells. Here, we consider possible reactions between the clinical platinum drugs cisplatin and oxaliplatin with penicillin G, an antibiotic added routinely to cell culture media to prevent bacterial contamination. Platinum has a high affinity for ligands with sulfur donors. Penicillin G is an unstable thioether that degrades in a range of pathways. Nuclear magnetic resonance (NMR) and UV-Vis absorption spectroscopic studies show that reactions with cisplatin can occur within minutes to hours at 310 K, but more slowly with oxaliplatin. The identities of the Pt- adducts were investigated by mass spectrometry. The marked effect on cytotoxicity of co-incubation of cisplatin with penicillin G was demonstrated for the HeLa human cervical cancer cell line. These studies highlight the possibility that reactions with penicillin G might influence the cytotoxic activity of metal complexes determined in culture media.

Is Penicillin Allergy a Risk Factor for Surgical Site Infection After Oral and Maxillofacial Surgery?

PURPOSE

The selection of perioperative antibiotics for prevention of surgical site infection (SSI) is often limited by the presence of a reported penicillin allergy. The purpose of this study was to determine if oral and maxillofacial surgery patients who report allergy to penicillin are at an increased risk of developing SSI.

METHODS

A retrospective cohort study was performed of patients who underwent oral and maxillofacial surgical procedures in the operating room setting at a single institution between 2011 and 2018. The following categories of procedures were investigated: dentoalveolar, orthognathic, orthognathic with third molar extraction, pathology and reconstruction, and temporomandibular joint. The primary predictor and outcome variables were reported penicillin allergy and surgical site infection, respectively. Bivariate and multiple logistic regression analysis were performed. P < .05 was considered to be significant.

RESULTS

The cohort was composed of 2,058 patients of which 318 (15.5%) reported allergy to penicillin. Beta-lactam antibiotics were administered less frequently to penicillin allergic patients perioperatively compared with those without penicillin allergy (7.9 vs 97.1%, P < .001), while clindamycin was more commonly administered (76.4 vs 2.5%, P < .001). Clindamycin was associated with a higher SSI rate compared with beta-lactam antibiotics (5.6 vs 1.4%, P < .001). Penicillin allergy was significantly associated with SSI at an adjusted odds ratio of 2.61 (95% CI 1.51 to 4.49, P = .001). After holding perioperative antibiotic usage equal between the 2 groups, penicillin allergy per se was no longer associated with SSI (P = .901), suggesting that the outcome was mediated by antibiotic selection.

CONCLUSIONS

Penicillin allergy was associated with development of SSI due to receipt of non-beta-lactam antibiotics as perioperative prophylaxis. Formal allergy evaluation should be considered for patients with putative penicillin allergy.

Allergy to penicillin and betalactam antibiotics

Betalactams are the most frequent cause of hypersensitivity reactions to drugs mediated by a specific immune mechanism. Immediate reactions occur within 1 to 6 hours after betalactam administration, and are generally IgE-mediated. They clinically translate into urticaria, angioedema and anaphylaxis. Non-immediate or delayed reactions occur after 1 hour of administration. These are the most common reactions and are usually mediated by T cells. The most frequent type is the maculopapular or morbilliform exanthematous eruption. Most individuals who report allergies to penicillin and betalactams can tolerate this group of antibiotics. To make diagnosis, a detailed medical history is essential to verify whether it was an immediate or non-immediate reaction. Thereafter, in vivo and/or in vitro tests for investigation may be performed. The challenging test is considered the gold standard method for diagnosis of betalactam hypersensitivity. The first approach when suspecting a reaction to betalactam is to discontinue exposure to the drug, and the only specific treatment is desensitization, which has very precise indications. The misdiagnosis of penicillin allergy affects the health system, since the "penicillin allergy" label is associated with increased bacterial resistance, higher rate of therapeutic failure, prolonged hospitalizations, readmissions, and increased costs. Thus, it is essential to develop strategies to assist the prescription of antibiotics in patients identified with a label of "betalactam allergy" at hospitals, and to enhance education of patients and their caregivers, as well as of non-specialist physicians.

Betalactam hypersensitivity: The importance of delabelling in primary care

PATIENTS AND METHODS

An allergy work-up was performed on adult patients with a history of a penicillin allergy seen by primary medical care in Monastir (Tunisia) between July 2016 and February 2018. Patients with negative skin tests were challenged with amoxicillin. Patients who were delabelled were contacted by phone after 6 months to determine outcomes after any therapeutic penicillin-class antibiotic intake.

RESULTS

A total of 39 patients were evaluated and 33 (84.6%) were delabelled. Five patients were penicillin skin-test positive and one was oral challenge positive. We succeeded in contacting 33 delabelled patients at 6 months. Twenty-two patients tolerated a subsequent therapeutic course of amoxicillin, eight patients did not retake penicillin due to a lack of therapeutic indication, and three patients refused an indicated penicillin use fearful of another reaction.

CONCLUSION

This study highlights the importance of allergy work-up in the diagnosis of beta-lactam hypersensitivity. Most patients were excessively labelled as beta-lactam allergic and this mislabelling could increase healthcare costs and lead to the development of drug resistance by the use of wide-spectrum antibiotics.

Alleged Allergy to Penicillin and Isolation Issues: Toward New Practices for French Navy?

INTRODUCTION

According to the literature, 8% of the population claim to have an allergy to penicillin. Allergy tests show that 90% of these patients tolerate this molecule. Physicians working in the French Navy are faced with situations of real isolation and only have a limited number of antibiotics on board, the majority of which are penicillins. They must anticipate the risks linked to the prescription of antibiotics before the mission. However, there is no French recommendation, either military or civilian, intended for general practitioners clarifying the management and allergy assessments of patients alleging a history of allergy to penicillin. This study is the first to evaluate the professional practices of French military practitioners taking care of these patients. The main objective was to evaluate the proportion of sailors who reported an allergy to penicillin and who have never been referred for a consultation with an allergist, by studying the medical files of all the submariners working on the submersible ballistic nuclear submarines squadron in Brest. The secondary objective was to compare these data with the practices of Navy doctors by means of questionnaires.

MATERIAL AND METHODS

Our work is composed of two parts: monocentric study of the digital and paper medical files of Brest submariners (n = 814) looking for allergist consultation reports in cases alleging an allergy to penicillin, then comparison with a multicentric collection of all Navy doctors' practices collected by an anonymized questionnaire (n = 37 out of 53 practicing at the time of the study).

RESULTS

Forty-seven subjects out of 814 alleged an allergy to penicillin (5.8%). Among them, only 12 (25.5%) had undergone allergy tests, of which 3 (6.4%) were confirmed to be allergic, with no cross-reaction between β-lactam antibiotics. Yet, according to the questionnaire, 25 doctors (67%) report referring their patients to an allergist and 16 (43%) report having had difficulties at sea in connection with the prescription of antibiotics for these patients.

CONCLUSIONS

A study of medical records shows that the allergic risk is not anticipated for 74.5% of patients labeled allergic, despite the difficulties encountered at sea. Standardization of practices within the French Navy is necessary to avoid the prescription of second-line antibiotics, less effective and sometimes unavailable on board, and to improve patient safety in isolation situations. In agreement with French military allergists, we propose, in this article, guidelines for a systematic exploration of allegations of allergy to penicillin in the French Navy.

Immune thrombocytopenia induced by beta-lactam antibiotics: Cross-reactions of responsible antibodies with other beta-lactam drugs

BACKGROUND

Beta-lactam antibiotics are a relatively common cause of immune thrombocytopenia. Because the many beta-lactam drugs now in clinical use have structural similarities, when a patient experiences this complication the question of whether an alternative member of this drug family can safely be used often arises but there are little data available to guide this decision.

STUDY DESIGN AND METHODS

Drug-dependent, platelet-reactive antibodies from 32 patients who experienced thrombocytopenia while being treated with a beta-lactam drug of the penam (piperacillin, etc.) or cephem (ceftriaxone etc.) groups were studied for serologic cross-reactivity with other drugs from these families using flow cytometry. Cross-reactions observed were analyzed for correlations with structural features of the drugs tested.

RESULTS

Among 14 antibodies specific for penam drugs, five "strong" cross-reactions with other penam drugs were found. Among 18 antibodies specific for cephem drugs, 8 "strong cross-reactions were identified. Antibodies induced by penam drugs did not cross-react strongly with cephem drugs and vice versa. A strong correlation between cross-reactions and similar or identical R1 side groups of the beta-lactams studied was observed.

DISCUSSION

The findings suggest that patients who experience immune thrombocytopenia while being treated with a beta-lactam of the penam group can safely be treated with a cephem drug and vice versa. If a patient is to be switched to another beta lactam within the same group, the likelihood of serologic cross-reactivity can be minimized by choosing an agent with a distinctly different R1 side group.

β-Lactam Allergy and Cross-Reactivity: A Clinician's Guide to Selecting an Alternative Antibiotic

β-Lactams which include penicillins, cephalosporins, carbapenems, and monobactams are the most common antibiotic classes reported to cause allergic reactions to drugs. This review is mainly about published studies assessing the cross-reactivity among β-lactams in penicillin- or cephalosporin-allergic subjects by carrying out diagnostic tests with alternative β-lactams and, if appropriate, graded challenges. Several studies demonstrated that cross-reactivity connected with the β-lactam ring, causing positive responses to allergy tests with all β-lactams, is infrequent in subjects with an IgE-mediated allergy and anecdotal in those with a T-cell-mediated allergy. Identities or similarities of β-lactam side-chain structures are mainly responsible for cross-reactivity among these antibiotics. For example, in aminopenicillin-allergic subjects, cross-reactivity with aminocephalosporins could possibly be over 30%. On the other hand, in a few prospective studies of penicillin-allergic individuals, less than 1% of cases show a cross-reactivity between penicillins and both aztreonam and carbapenems. Particular patterns of allergy-test positivity observed in some studies that assessed cross-reactivity among β-lactams seem to indicate that prior exposures may be responsible for coexisting sensitivities. Therefore, pre-treatment skin tests with the related β-lactams are suggested before administering them via graded challenges to β-lactam-allergic patients who need alternative β-lactams.

Inappropriate Use of Aztreonam

BACKGROUND

Aztreonam is not a preferred empiric antibiotic because of variable susceptibilities compared with alternative agents. In addition, it has no Gram-positive activity, necessitating coadministration with vancomycin when used empirically, and is more costly when compared with other Gram-negative active agents. Aztreonam is often given to patients with a reported penicillin allergy without further investigation into the reaction or other relevant allergy information.

STUDY QUESTION

How frequently is aztreonam being used inappropriately?

STUDY DESIGN

We conducted a retrospective chart review at an academic medical center to assess the appropriateness of our aztreonam use.

MEASURES AND OUTCOMES

Our primary outcome was frequency of appropriate aztreonam use, based on a true IgE-mediated allergy reported for each patient. We evaluated whether the patients had tolerated a beta-lactam in the past, and what the reported allergic reaction was.

RESULTS

We included 165 patients and found that 46.7% of our aztreonam use was inappropriate, based on previous use of a beta-lactam, or no documentation of an IgE-mediated response. Of the patients with a documented beta-lactam allergy, 63 (38.2%) patients had no allergy manifestation listed, and 37 (22.4%) patients had a non-IgE-mediated allergy manifestation. Of the total population, 61 (37%) patients had tolerated a beta-lactam in the past.

CONCLUSIONS

Aztreonam should be avoided, except in the case of a true IgE-mediated allergic reaction. Our goal was to reduce the inappropriate use of aztreonam at our institution by one or more of the following: educating providers, reviewing aztreonam orders, requiring answering of order questions, or requiring an indication for use. Penicillin skin testing and desensitization are options as well.

Penicillin Allergy Delabeling Can Decrease Antibiotic Resistance, Reduce Costs, and Optimize Patient Outcomes

Background

Antibiotics are one of the most frequently prescribed medications. Among all classes of antibiotics, penicillins are prescribed due to their clinical efficacy, cost-effectiveness, and general safety. Unfortunately, penicillins also are the most common drug allergy listed in patient medical records. Increasing evidence shows that > 90% of patients labeled with a penicillin allergy are not allergic to penicillins and associated β-lactams. The health care consequences of penicillin allergy in the setting of military medicine and readiness are important to consider.

Observations

In the US, 8 to 10% of the population and up to 15% of hospitalized patients have a documented penicillin allergy, limiting the use of these effective antibiotics. When treating a patient with a penicillin allergy, many clinicians avoid prescribing all β-lactam antibiotics and stay away from cephalosporins due to the concern for potential cross-reactivity. The cost of treating those with a documented penicillin allergy is greater than the cost for those who can receive penicillin, as treatment with broad-spectrum antibiotics often results in longer hospitalizations with increased rates of adverse effects (AEs). Despite preventive programs such as vaccinations, hygiene measures, and prophylactic antibiotics, military personnel are at increased risk for infections due to the military's mobile nature and crowded living situations.

Conclusions

Many patients report an allergy to penicillin, but only a small portion have a true immune-mediated allergy. Given the clinical, public health, and economic costs associated with a penicillin allergy label, evaluation and clearance of penicillin allergies improves clinical outcomes, decreases AEs from higher risk alternative broad-spectrum antibiotics, and prevents the spread of antibiotic resistance. In military personnel, penicillin delabeling improves readiness with optimal antibiotic options and avoidance of unnecessary risks, expediting return to full duty.

[Update on perioperative hypersensitivity reactions: joint document from the Brazilian Society of Anesthesiology (SBA) and Brazilian Association of Allergy and Immunology (ASBAI) - Part II: etiology and diagnosis]

This second joint document, written by experts from the Brazilian Association of Allergy and Immunology (ASBAI) and Brazilian Society of Anesthesiology (SBA) concerned with perioperative anaphylaxis, aims to review the pathophysiological reaction mechanisms, triggering agents (in adults and children), and the approach for diagnosis during and after an episode of anaphylaxis. As anaphylaxis assessment is extensive, the identification of medications, antiseptics and other substances used at each setting, the comprehensive data documentation, and the use of standardized nomenclature are key points for obtaining more consistent epidemiological information on perioperative anaphylaxis.

Update on perioperative hypersensitivity reactions: joint document from the Brazilian Society of Anesthesiology (SBA) and Brazilian Association of Allergy and Immunology (ASBAI) - Part II: etiology and diagnosis

This second joint document, written by experts from the Brazilian Association of Allergy and Immunology (ASBAI) and Brazilian Society of Anesthesiology (SBA) concerned with perioperative anaphylaxis, aims to review the pathophysiological reaction mechanisms, triggering agents (in adults and children), and the approach for diagnosis during and after an episode of anaphylaxis. As anaphylaxis assessment is extensive, the identification of medications, antiseptics and other substances used at each setting, the comprehensive data documentation, and the use of standardized nomenclature are key points for obtaining more consistent epidemiological information on perioperative anaphylaxis.

Neo-antigens for the serological diagnosis of IgE-mediated drug allergic reactions to antibiotics cephalosporin, carbapenem and monobactam

New antigens deriving from -lloyl and -llanyl, major and minor determinants, respectively, were produced for β-lactam antibiotics cefuroxime, cefotaxime, ceftriaxone, meropenem and aztreonam. Twenty β-lactam antigens were produced using human serum albumin and histone H1 as carrier proteins. Antigens were tested by multiplex in vitro immunoassays and evaluated based on the detection of specific IgG and IgE in the serum samples. Both major and minor determinants were appropriate antigens for detecting specific anti-β-lactam IgG in immunised rabbit sera. In a cohort of 37 allergic patients, we observed that only the minor determinants (-llanyl antigens) were suitable for determining specific anti-β-lactam IgE antibodies with high sensitivity (< 0.01 IU/mL; 24 ng/L) and specificity (100%). These findings reveal that not only the haptenisation of β-lactam antibiotics renders improved molecular recognition events when the 4-member β-lactam ring remains unmodified, but also may contribute to develop promising minor antigens suitable for detecting specific IgE-mediated allergic reactions. This will facilitate the development of sensitive and selective multiplexed in vitro tests for drug-allergy diagnoses to antibiotics cephalosporin, carbapenem and monobactam.

Perioperative Clindamycin Use in Penicillin Allergic Patients Is Associated With a Higher Risk of Infection After Shoulder Arthroplasty

BACKGROUND

This study determines whether infection rates differ between prophylactic antibiotic use for patients with or without penicillin allergy before shoulder arthroplasty surgery.

METHODS

Seven thousand one hundred forty primary shoulder arthroplasties operated between 2005 and 2016 were identified. We compared deep surgical site infection risk of patients who received perioperative vancomycin alone (6.2%, N = 444) or clindamycin alone (7.1%, N = 508) for penicillin allergy versus patients who received cefazolin alone without penicillin allergy (86.7%, N = 6,188).

RESULTS

Seventy deep infections (1.2% 5-year cumulative incidence) were observed. The most common organism was Cutibacterium acnes (39.4%, N = 27). Compared with patients treated with cefazolin, infection risk was not different for those treated with vancomycin (hazard ratio = 1.17, 95% confidence interval 0.42 to 3.30, P = 0.8), but a higher risk of infection was identified for those treated with clindamycin alone (hazard ratio = 3.45, 95% confidence interval 1.84 to 6.47, P < 0.001).

CONCLUSION

A higher risk of postoperative infection is found after prophylactic use of intravenous clindamycin antibiotic after shoulder arthroplasty. Vancomycin is preferred over clindamycin for patients with penicillin allergy.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Penicillin Allergy…Maybe Not? The Military Relevance for Penicillin Testing and De-labeling

INTRODUCTION

Penicillin allergy is the most common drug allergy reported. About 8-10% of individuals in the USA have a documented penicillin allergy, yet 90% are not truly allergic to penicillin. A penicillin allergy "label" results in increased antibiotic-related adverse reactions and increased health care costs, thus impacting the overall "readiness" of the military.

MATERIALS AND METHODS

A review of the current literature and approaches to penicillin allergy and "de-labeling" a patient who reports penicillin allergy was conducted and future strategies to identify and assess military beneficiaries were outlined. Military allergists had a formal discussion at the Tri-service Military Allergy Immunology Assembly regarding the state of penicillin allergy testing in military allergy clinics.

RESULTS

A PubMed search yielded 5,775 results for "penicillin allergy" and 484 results for "penicillin allergy testing." There were two formalized penicillin testing programs in the military treatment facilities. In 2017, the military trained nearly 165,000 new recruits. If 5-10% reported a penicillin allergy and 90% were de-labeled, that would yield a $15-30 million cost savings annually. Further, de-labeling of the 9.4 million active duty, beneficiaries and retirees with a 90% success rate could result in even greater savings for the military health care system.

CONCLUSION

A penicillin allergy label is a risk to military readiness secondary to associated increases in the length of hospitalizations and emergency department and medical visits. Penicillin de-labeling is a simple intervention that can improve readiness, significantly decrease health care costs and prevent antibiotic resistance, as well as antibiotic-associated adverse events. The military allergist should be "front and center" providing expertise guidance and leadership for clinic and hospital-based penicillin de-labeling efforts which are nested within the antibiotic stewardship programs.

An update on allergy and anaphylaxis in pediatric anesthesia

Childhood allergy is common, and increasing. Many children are incorrectly labeled as having allergy or adverse drug reactions. This can pose a dilemma for anesthetists and lead to a change in practice or drug selection. We review the pathophysiology of hypersensitivity reactions and the implications for anesthesia of food allergy, atopy, and family history of allergy in children. The epidemiology of anaphylaxis is discussed. We discuss the common triggers of perioperative anaphylaxis in children and explore emerging triggers including chlorhexidine and sugammadex. Accurate data on pediatric perioperative anaphylaxis is limited worldwide, with marked geographic variation. This highlights the need for accurate local, district and/or nationwide incident reporting. The clinical features, diagnosis, and management of anaphylaxis under anesthesia are discussed. We review the process of expert allergy testing following a suspected case of anaphylaxis to guide future safe anesthesia administration. The preoperative consultation is an opportunity for referral for allergy testing to allow de-labeling. This has the potential for improved antibiotic stewardship and more effective treatment with first-line therapeutic agents.

Risk of Adverse Reactions to Oral Antibiotics Prescribed by Dentists

Dentists prescribe a large portion of all oral antibiotics, and these are associated with a risk of adverse drug reactions (ADRs). The aim of this study was to quantify the risk of ADRs associated with oral antibiotics commonly prescribed by dentists. NHS Digital Prescribing data and Yellow Card Drug Analysis data for 2010 to 2017 were abstracted to quantify dental antibiotic prescribing in England, and the rate and types of ADRs associated with them. During the period of study, the mean number of actively practicing dentists in England was 23,624. Amoxicillin accounted for 64.8% of dental antibiotic prescribing and had the lowest reported rate of fatal ADRs (0.1/million prescriptions) and overall ADRs (21.5/million prescriptions). Indeed, amoxicillin was respectively 6 and 3 times less likely to cause an ADR than the other penicillins, penicillin V and amoxicillin + clavulanic acid, and appears to be very safe in patients with no history of penicillin allergy. In contrast, clindamycin, which is often used in patients with penicillin allergy, had the highest rate of fatal (2.9/million prescriptions) and overall (337.3/million prescriptions) ADRs, with Clostridiodes (formerly Clostridium) difficile infections pivotal to its ADR profile. Other amoxicillin alternatives, clarithromycin and metronidazole, while significantly worse than amoxicillin, were 3 and nearly 5 times less likely to cause an ADR than clindamycin. Ranked from least to most likely to cause an ADR, antibiotics most commonly prescribed were as follows: amoxicillin < cephalosporins < erythromycin < tetracyclines < azithromycin < metronidazole < amoxicillin + clavulanic acid < clarithromycin < penicillin V < clindamycin. This study confirmed the high level of safety associated with use of amoxicillin by dentists and the significantly worse rates of fatal and nonfatal ADRs associated with other penicillins and alternatives to amoxicillin for those who are penicillin allergic. In particular, clindamycin had the highest rate of fatal and nonfatal ADRs of any of the antibiotics commonly prescribed by dentists.

Antibiotic Hypersensitivity Mechanisms

Antibiotics are commonly prescribed to treat a variety of bacterial infections. As with all medications, hypersensitivity reactions may occur and clinicians should be able to recognize them accurately and recommend appropriate management. Antibiotic related hypersensitivity reactions may be one of four different types: Type I reactions, which are IgE mediated and may lead to anaphylaxis; Type II reactions that are antibody-mediated and may result in thrombocytopenia, neutropenia, or hemolytic anemia; Type III reaction that involves an immune complex formation such as vasculitis; and Type IV reactions that consist of four subtypes and typically include a rash of varying level of severity with or without systemic signs and symptoms. Herein, we describe the mechanisms of different types of allergic reactions to commonly prescribed antibiotics and offer recommendations for management. Further, we briefly refer to antibiotic reactions that mimic hypersensitivity reactions but are not immune mediated, such as pseudoallergies and serum sickness-like reactions.

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

BACKGROUND

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

The safety of treatment options for acute bacterial skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin-structure infections (ABSSSI) may develop in both in-patients and out-patients, possibly with a severe clinical presentation. Since most phase 3 randomized clinical trials have shown non-inferiority in efficacy across different agents, considerations regarding their different safety profiles inevitably play a crucial role in the everyday choice about which of them should be employed for the treatment of ABSSSI.

AREAS COVERED

In this review, the authors discuss the safety profile of different treatment options for ABSSSI.

EXPERT OPINION

The spread of methicillin-resistant Staphylococcus aureus (MRSA) in the last decades has inevitably influenced the therapeutic approach to ABSSSI. Adequate knowledge of the peculiar toxicity profile of each drug active against MRSA is essential for guiding, monitoring and managing adverse events, in turn reducing any unfavorable impact of toxicity on patients' outcomes. In the next five years, potential toxicity will play a critical role in establishing the best available therapy for each specific patient, together with consideration regarding the possibility of avoiding hospitalization or allowing a switch from intravenous to oral therapy and early discharge.

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.

The Limited Value of Prolonged Drug Challenges in Nonimmediate Amoxicillin (Clavulanic Acid) Hypersensitivity

BACKGROUND

Misdiagnosis of amoxicillin (clavulanic acid) (AX(/CL)) hypersensitivity has serious consequences. A drug challenge (DC) is the final diagnostic to affirm or infirm AX(/CL) hypersensitivity. However, uncertainties remain whether a prolonged drug challenge (pDC) should benefit the diagnosis of a nonimmediate AX(/CL) hypersensitivity.

OBJECTIVE

To assess the added value of a standardized 7-day pDC in the diagnosis of nonimmediate or unclear penicillin hypersensitivity.

METHODS

A total of 132 patients with a history of a nonimmediate hypersensitivity reaction or an unclear reaction to AX(/CL) or an undefined penicillin with a negative diagnostic workup including a single-day DC (DC) with AX(/CL) were selected. In all these patients, an additional pDC with AX(/CL) was planned. Thirteen patients started the pDC immediately after the DC. To ensure that hypersensitivity symptoms manifesting during the pDC course do not result from the DC, in the remaining 119 patients, the pDC was scheduled after a washout of 1 week.

RESULTS

A total of 128 patients (12 without washout, 116 with washout) completed the pDC. Three patients reacted with a mild maculopapular exanthema. However, the value of a pDC was evidenced in only 1 patient who reacted during her pDC after an uneventful washout. In 2 patients pDC was cancelled because they reacted during the washout.

CONCLUSIONS

A pDC is of limited added value to the diagnostic algorithms of nonimmediate hypersensitivity reaction or unclear hypersensitivity reactions to AX(/CL). In our hands, the traditionally recommended diagnostic algorithm that offers a 1-day DC as a final diagnostic in patients with negative workup for AX(/CL) is appropriate.

Current and emerging pharmacotherapy for the treatment of infections following open-heart surgery

INTRODUCTION

Patients undergoing open-heart surgery may suffer from postoperative complications, including severe infections. Antimicrobials to treat infectious complications in this population should be selected thoughtfully, taking into account three different and fundamental issues: (i) the site of infection; (ii) the suspected or proven causative agent and its susceptibility pattern; and (iii) the risk of suboptimal pharmacokinetic characteristics and potential toxicity of the chosen drug/s.

AREAS COVERED

The present narrative review summarizes the current and future antimicrobial options for the treatment of infections developing after open-heart surgery.

EXPERT OPINION

The pharmacological treatment of infections developing in cardiac surgery patients poses peculiar challenges, including the need for an active empirical therapy for severe events such as bloodstream infections, deep sternal wound infections, or early-onset postoperative prosthetic endocarditis. In addition, the risk for multidrug-resistant pathogens should also be taken into account in endemic areas. A multidisciplinary evaluation on a patient-by-patient basis, deeply involving infectious diseases specialists and cardiothoracic surgeons, remains essential for appropriately balancing both short-term and long-term risks and benefits of any possible surgical reintervention in combination with adequate pharmacotherapy.

A practical management of children with antibiotic allergy

About 10% of the parents reported that their children are allergic to one drug and the betalactam antibiotics are the most frequently suspected. Even if most of the adverse events following antibiotic prescriptions to children are considered allergic, after a full allergy work-up only a few of the suspected reactions are confirmed. For this reason, many children are incorrectly labelled as "allergic" and this represents an important challenge for the choice of the antibiotic therapy in these "labelled" children, who are frequently improperly deprived of narrow-spectrum antibiotics because considered as allergic. When an allergic reaction is suspected a precise diagnosis and a choice of a safe and effective alternative is essential for the future antibiotic option. In the light of this, the main aim of this paper is to try to provide a practical approach to managing the individuals who have reported adverse reactions to antibiotics.

Proper Cut-off Levels of Serum Specific IgE to Cefaclor for Patients with Cefaclor Allergy

PURPOSE

Cefaclor, a second-generation oral cephalosporin, is known to cause IgE-mediated hypersensitivity. Assays of serum-specific IgE (sIgE) to cefaclor are commercially available via the ImmunoCAP system (Thermo Fisher Scientific). While serum levels of sIgE >0.35 kU/L are considered indicative of an allergy, some patients with cefaclor allergy show low serum IgE levels. This study aimed to evaluate the proper cut-off levels of sIgE in the diagnosis of immediate hypersensitivity to cefaclor.

MATERIALS AND METHODS

A total of 269 patients with drug allergy history, who underwent assays of sIgE to cefaclor at Ajou University hospital and Dong-A University Hospital, were reviewed retrospectively. Among them, 193 patients exhibited cefaclor-induced immediate hypersensitivity with certain or probable causality of an adverse drug reaction according to the WHO-UMC (the World Health Organization-the Uppsala Monitoring Centre) algorithm, and 76 controls showed delayed hypersensitivity reactions to non-antibiotics.

RESULTS

In total, 126 of the 193 patients (65.3%) experienced anaphylaxis; they had higher serum sIgE levels than patients with immediate hypersensitivity who did not experience anaphylaxis (6.36±12.39 kU/L vs. 4.28±13.61 kU/L, p<0.001). The best cut-off value for cefaclor-induced immediate hypersensitivity was 0.11 kU/L, with sensitivity of 80.2% and specificity of 81.6%. A cut-off value of 0.44 kU/L showed the best sensitivity (75.4%) and specificity (65.7%) for differentiating anaphylaxis from immediate hypersensitivity reactions.

CONCLUSION

Patients with cefaclor anaphylaxis exhibit high serum IgE levels. A cut-off value of 0.11 kU/L of sIgE to cefaclor is proper for identifying patients with cefaclor allergy, and 0.44 kU/L may be useful to detect anaphylaxis.

Management of Pediatric Acute Hematogenous Osteomyelitis, Part I: Antimicrobial Stewardship Approach and Review of Therapies for Methicillin-Susceptible Staphylococcus aureus, Streptococcus pyogenes, and Kingella kingae

Acute hematogenous osteomyelitis (AHO), often occurring in young children, is the most frequently diagnosed type of osteomyelitis in pediatric patients. Optimizing antibiotics is essential as delays to receipt of appropriate therapy can lead to chronic osteomyelitis, as well as impairments in bone growth and development. Antimicrobial stewardship programs (ASPs) are in a key position to help improve the care of patients with AHO as they contain a pharmacist with expertise in antibiotic drug selection, optimization of dosing, and microbiologic test review. A literature search of the MEDLINE database was conducted from initiation through January 2018. Articles selected for the review focus on pathogen identification, pharmacokinetics and pharmacodynamics, efficacy and safety in children, transition from intravenous to oral therapy, duration of treatment, and antimicrobial stewardship interventions. This review will highlight the potential roles ASPs can have in improving the management of AHO in pediatric patients. These roles include the creation of clinical pathways, improving testing algorithms, antibiotic choice and dosing, intravenous to oral transitions, duration of treatment, and therapy monitoring. Overall, patients are most effectively treated by focusing treatments on age, presentation, local sensitivities, and directed therapy with pathogen identification.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Crystal structures of two (Z)-2-(4-oxo-1,3-thia-zolidin-2-yl-idene)acetamides

The crystal structures of two (oxo­thia­zolidin-2-yl­idene)acetamides, namely (Z)-2-[2-(morpholin-4-yl)-2-oxo­ethyl­idene]thia­zolidin-4-one and (Z)-N-(4-meth­oxy­phen­yl)-2-(4-oxo­thia­zolidin-2-yl­idene)acetamide are described and compared with a related structure.

The crystal structures of two (oxo­thia­zolidin-2-yl­idene)acetamides, namely (Z)-2-[2-(morpholin-4-yl)-2-oxo­ethyl­idene]thia­zolidin-4-one, C₉H₁₂N₂O₃S, (I), and (Z)-N-(4-meth­oxy­phen­yl)-2-(4-oxo­thia­zolidin-2-yl­idene)acetamide, C₁₂H₁₂N₂O₃S, (II), are described and compared with a related structure. The Z conformation was observed for both the compounds. In (I), the morpholin-4-yl ring has a chair conformation and its mean plane is inclined to the thia­zolidine ring mean plane by 37.12 (12)°. In (II), the benzene ring is inclined to the mean plane of the thia­zolidine ring by 20.34 (14)°. In the crystal of (I), mol­ecules are linked by N—H⋯O hydrogen bonds, forming C(6) chains along the b-axis direction. The edge-to-edge arrangement of the mol­ecules results in short C—H⋯O and C—H⋯S inter­actions, which consolidate the chain into a ribbon-like structure. In the crystal of (II), two N—H⋯O hydrogen bonds result in the formation of C(8) chains along the b-axis direction and C(6) chains along the c-axis direction. The combination of these inter­actions leads to the formation of layers parallel to the bc plane, enclosing R₄⁴(28) rings involving four mol­ecules.