Antimicrobial consumption in an acute NHS Trust during the COVID-19 pandemic: intervention time series analysis

Objective

To determine the impact of the COVID-19 pandemic on antimicrobial consumption and trends of therapeutic drugs for COVID-19 treatments, including corticosteroids, remdesivir and monoclonal antibodies (tocilizumab) from April 2017 to September 2022 in a secondary care NHS Trust in England.

Methods

A retrospective intervention time series analysis was conducted for April 2017 to September 2022 at the Mid Yorkshire Teaching NHS Trust. Data were retrieved from the pharmacy dispensing system as defined daily doses (DDDs) monthly and reported per 1000 occupied bed days (OBDs). Antimicrobial consumption and COVID-19 treatment options were measured. DDDs were calculated according to the classification of antimicrobials for systemic use (J01) and for other drugs classification. Trends for antimicrobial consumption and other therapeutic drugs for treating COVID-19 were also determined in each wave in England.

Results

During the pandemic: total antibiotic consumption decreased from 826.4 to 728.2 DDDs per 1000 OBDs (P = 0.0067); piperacillin/tazobactam use increased (P < 0.0001) and ciprofloxacin use decreased (P < 0.0001); there were no changes in Access, Watch, Reserve antibiotic use, and the proportion of antifungal consumption was consistent throughout the study. The use of total antibiotics (P = 0.024), levofloxacin (P = 0.0007), piperacillin/tazobactam (P = 0.0015) and co-amoxiclav (P = 0.0198) increased during wave one. Consumption of COVID-19 treatment drugs was highest during wave two, with 624.3 DDDs per 1000 OBDs for dexamethasone (P = 0.4441), 6.8 DDDs per 1000 OBDs for remdesivir (P < 0.0001) and 35.01 DDDs per 1000 OBDs for tocilizumab (P = 0.2544).

Discussion

This study determined the consumption of antimicrobials trends before and during the pandemic. The individual wave antimicrobial consumption indicates maximum consumption in the first wave, advocating for antimicrobial stewardship and preparedness for future pandemics.

Exploring drivers and challenges influencing antibiotic prescribing in outpatient settings and possible mitigation strategies in the United Arab Emirates: a qualitative study

Objectives

Healthcare institutions implement antimicrobial stewardship (AMS) programmes to optimize the use of antibiotics. The focus is often on inpatient rather than outpatient settings. We aimed to explore perceptions of AMS stakeholders on effective interventions for appropriate antibiotic use in outpatient settings, and the role of clinical pharmacists in the AMS multidisciplinary team.

Methods

A qualitative semi-structured interview study using thematic analysis by two researchers independently. Participants that practice AMS programmes were recruited from healthcare facilities in the United Arab Emirates (UAE). Interviews were conducted face to face or online and transcribed verbatim.

Results

Four themes emerged: (i) Perceived factors leading to unnecessary or inappropriate antibiotic prescribing and their impact on patients and the community; (ii) current outpatient AMS activities and perceived barriers and facilitators for their sustainability; (iii) suggested outpatient AMS strategies to be implemented in outpatient settings; and (iv) perceived future AMS implementation barriers and suggested mitigation strategies.

Conclusions

Several AMS interventions, together with the presence of a clinical pharmacist, may be effective in improving antibiotic use in UAE outpatient settings. Future research should investigate the most appropriate AMS strategy considering barriers and possible mitigation strategies to ensure sustainability.

Feasibility, Effectiveness and Safety of Elastomeric Pumps for Delivery of Antibiotics to Adult Hospital Inpatients-A Systematic Review

Elastomeric infusion pumps (EMPs) have been implemented in many fields, including analgesia, chemotherapy and cardiology. Their application in antimicrobials is mainly limited to the outpatient setting, but with a need to optimise inpatient antimicrobial treatment, the use of EMPs presents a potential option. This review aimed to identify if the use of EMPs within an inpatient setting is feasible, effective and safe for antimicrobial use. Criteria for inclusion were human studies that involved the treatment of an infection with intravenous antimicrobial agents via an EMP. A search strategy was developed covering both the indexed and grey literature, with all study designs included. The review found 1 eligible study enrolling 6 patients. There was strong patient preference for EMPs (6/6), and daily tasks were easily completed whilst attached to the EMP. Nurses (5/5) also preffered the pumps, and the majority reported them as easy to use. The review has identified the need for further research in the area. Evidence for the use of EMPs to administer antibiotics in the inpatient setting is scarce, and more work is needed to understand the advantages to patients, to healthcare workers and from an antimicrobial stewardship perspective. Potential disadvantages that may put patients at risk also need investigating.

Identification of antibiotic consumption targets for the management of Clostridioides difficile infection in hospitals- a threshold logistic modelling approach

BACKGROUND

This study aims to demonstrate the utility of a threshold logistic approach to identifying thresholds for specific antibiotic use associated with Clostridioides difficile infection (CDI) in an English teaching hospital.

METHODS

A combined approach of nonlinear modeling and logistic regression, named threshold logistic, was used to identify thresholds and risk scores in hospital-level antibiotic use associated with hospital-onset, healthcare-associated (HOHA) CDI cases.

RESULTS

Using a threshold logistic regression approach, an incidence greater than 0.2645 cases/1000 occupied bed-days (OBD; 85th percentile) was determined as the cutoff rate to define a critical (high) incidence rate of HOHA CDI. Fluoroquinolones and piperacillin-tazobactam were found to have thresholds at 84.8 and 54 defined daily doses (DDD)/1000 OBD, respectively. Analysis of data allowed calculating risk scores for HOHA CDI incidence rates exceeding the 85th percentile, i.e. entering critical incidence level. The threshold-logistic model also facilitated performing 'what-if scenarios' on future values of fluoroquinolones and piperacillin-tazobactam use to understand how HOHA CDI incidence rates may be affected.

CONCLUSION

Using threshold logistic analysis, critical incidence levels and antibiotic use targets to control HOHA CDI were determined. Threshold logistic models can be used to inform and enhance the effective design and implementation of antimicrobial stewardship programs.

Exploring Thresholds and Interaction Effects Among Antibiotic Usage, Covariates, and their Effect on Antibiotic Resistance using an Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae Case

BACKGROUND

This study was aimed to explore thresholds with interaction effects among antibiotic usage, covariates (alcohol-based hand rub (ABHR)), and their effect on extended-spectrum β-lactamase - producing Klebsiella pneumoniae (ESBL-producing K. pneumoniae) in hospitalized patients.

METHODS

Multivariate Adaptive Regression Splines models were used. These considered second order interactions among antibiotic use and ABHR in addition to potential thresholds that further improve explained variance in the ESBL-producing K. pneumoniae response. The study involved collecting monthly hospital-level data for January 2017- December 2021. Results: Analysis of the main effects showed that third-generation cephalosporins above 2.00 DDD/100 occupied bed days (OBD) generally increased ESBL-producing K. pneumoniae incidence (cases/100 OBD). Levels of ABHR above 6.61 L/100 OBD were shown to generally decrease ESBL-producing K. pneumoniae incidence. Second order interactions revealed that when third-generation cephalosporin use was greater than 3.71 DDD/100 OBD, and ABHR was greater than 6.6 L/100 OBD (same as main effect threshold), ABHR partially lost effectiveness in its ability to reduce ESBL-producing K. pneumoniae incidence. This demonstrates the importance of not exceeding the identified thresholds of 3.71 DDD/100 OBD for third-generation cephalosporin use.

CONCLUSION

The Interaction model increased effectiveness to explain variation of ESBL-producing K. pneumoniae incidence rates while showing the importance of exploring interactions when modeling the relationship between antibiotic use, covariates (ABHR), and resistance in hospitals. The main-effect thresholds in third-generation cephalosporins and ABHR, and the identified interaction between third generation cephalosporins and ABHR, can inform effective hospital antimicrobial stewardship.

Public knowledge of antibiotics, self-medication, and household disposal practices in Jordan

BACKGROUND

This study aimed to assess public understanding of antibiotics, self-medication, and drug disposal practices.

METHODS

A cross-sectional self-administered online survey was undertaken in Jordan.

RESULTS

The study was completed by 1,105 participants. When asked about their knowledge of antibiotics, rational antibiotic use, and disposal practices, 16% percent believed they should discontinue antibiotics once they felt better, and 12% agreed to take the same antibiotics prescribed to others for the same illness. Self-medication with antibiotics was practiced by 44% of the participants. Prior experience, healthcare costs, and pharmacy location were all major determinants of self-medication. Only 6.4% of unneeded antibiotics were returned to the pharmacy, 60% were kept at home, and 26.6% were disposed of at home. Almost half of those who kept the antibiotics said they would use them again, and one-third said they would give them to friends and family. Respondents who had used antibiotics within the previous 6 months (p = 0.052) and relied on medication leaflets (p = 0.031) and physician recommendations (p = 0.001) were less likely to self-medicate with antibiotics.

CONCLUSIONS

The study highlighted areas of inappropriate use of antibiotics, self-medication and the improper antibiotic disposal that can inform antimicrobial stewardship.

P02 Novel pharmacy roles strengthen the multidisciplinary hospital infection team

Background

Pharmacists have an essential role to play in the NHS Long Term Plan. Hospital pharmacy departments need to develop novel roles to strengthen teams and improve patient care. In September 2017, Mid Yorkshire Hospitals NHS Trust appointed a consultant antimicrobial pharmacist along with an administrative apprentice to strengthen pharmacy and infection leadership and support the delivery of the antimicrobial resistance national targets. From January 2018 to June 2020, the infection team worked with locums but no substantive consultant microbiologists.

Objectives

To describe the benefits of developing novel pharmacy roles to strengthen an infection multidisciplinary team

Methods

A shortage of consultant microbiologists provided opportunities to develop and enhance other infection roles. These included one year of funding from Pathology for a Band 6 Specialist Pharmacy Technician. The role was subsequently funded by the Adult Community Services team to support the home intravenous antibiotic service. Senior support was provided by the Pathology Group Manager, Head of Infection Prevention and Control and Director of Pharmacy. The apprenticeship levy supported a Level 4 Data analyst qualification to develop the pharmacy administrator role. Two other infection roles were developed: Advanced Clinical Practitioner and Trainee Clinical Scientist, both of which could not be sustained for lack of adequate consultant microbiologist resources for clinical supervision within the team.

Results

The Specialist Pharmacy Technician coordinates the home intravenous antibiotic service. Clinical responsibility remains with the discharging consultant medical officer. The antimicrobial pharmacy team led the introduction of antibiotic elastomeric pumps for home use, saving 2500 inpatient bed days. Patient and staff feedback on the novel pharmacy roles has been positive. Band 5 Pharmacy Data Analyst – Antimicrobials responsibilities include clinical trial participation, data collection and analysis including ward level working, reporting and coordination of the audit programme. The role has enabled contribution to national research studies, including Antibiotic Review Kit (ARK-Hospital) and Procalcitonin: Evaluation of Antibiotic Use in COVID-19 Hospitalised Patients (PEACH). Through a new strategy, consultant microbiologist workforce has progressively grown back to three full time equivalents and a 4th post advertised, enabling an increase in participation in ward rounds, multidisciplinary team meetings, antimicrobial stewardship, infection prevention & control, Director of Infection Prevention and Control role and leading NIHR research trials. The consultant pharmacist remains in post as a senior leader, and also has a Trust role as Director of Innovation. This change provided funding for an increase from Band 3 to Band 5 data analyst, promotion of a senior Band 7 pharmacist to a Band 8a advanced clinical pharmacist, and conversion of a part time Band 7 pharmacist to a full-time role.

Discussion

An innovative approach to development of pharmacy, data, nurse and scientist roles has strengthened the infection service in a regional hospital and community services Trust. Pharmacy-led team meetings are now routine in the Trust allowing for more efficient use of consultant microbiologist time.

Conclusions

Potential future roles are further administrative support, pharmacy assistant, clinical nurse specialist – antimicrobials, and antimicrobial pharmacy team leader.

COVID-19 Mixed Impact on Hospital Antimicrobial Stewardship Activities: A Qualitative Study in UK-Based Hospitals

Antimicrobial resistance (AMR) is a well-known global threat due to the subsequent increase in antimicrobial usage. Several antimicrobial stewardship (AMS) strategies have been implemented to curb irrational prescribing and reduce the AMR burden. However, since the beginning of the COVID-19 pandemic, it has enormously impacted the healthcare system and jeopardized public health, causing millions of deaths globally. Our semi-structured qualitative study aimed to explore the impact of COVID-19 on AMS activities in the UK hospitals. Seventeen interviews were conducted with health care professionals who were part of AMS teams (consultant medical microbiologists, infectious disease consultants, antimicrobial pharmacists). Interviews were audio-recorded and transcribed. An inductive thematic framework was adopted to analyse and create the themes. After agreement of the hierarchical framework definition, all transcripts were coded accordingly. Four main themes and 15 sub-themes were identified. These main themes were: (1) AMS activities or strategies before and during the pandemic; (2) challenges to implementing AMS activities before and during the pandemic; (3) information from public authorities on AMS during the pandemic; and (4) new AMS activities/strategies adopted during the pandemic. Staff vacancies, redeploying of AMS staff to other duties and meeting the burden related to the COVID-19 and lack of resources were the most frequently identified contributing factors to withheld AMS activities during the pandemic. However, modifications to the hybrid working environment, i.e., remote or flexible working, allowed for resumption of AMS activities including virtual ward rounds, virtual meetings and other activities. Further research needs to assess the impact of the hybrid delivery system on AMS activities.

Exploring Antimicrobial Stewardship Influential Interventions on Improving Antibiotic Utilization in Outpatient and Inpatient Settings: A Systematic Review and Meta-Analysis

Antimicrobial stewardship interventions are targeted efforts by healthcare organizations to optimize antimicrobial use in clinical practice. The study aimed to explore effective interventions in improving antimicrobial use in hospitals. Literature was systemically searched for interventional studies through PubMed, CINAHL, and Scopus databases that were published in the period between January 2010 to April 2022. A random-effects model was used to pool and evaluate data from eligible studies that reported antimicrobial stewardship (AMS) interventions in outpatient and inpatient settings. Pooled estimates presented as proportions and standardized mean differences. Forty-eight articles were included in this review: 32 in inpatient and 16 in outpatient settings. Seventeen interventions have been identified, and eight outcomes have been targeted. AMS interventions improved clinical, microbiological, and cost outcomes in most studies. When comparing non-intervention with intervention groups using meta-analysis, there was an insignificant reduction in length of stay (MD: -0.99; 95% CI: -2.38, 0.39) and a significant reduction in antibiotics' days of therapy (MD: -2.73; 95% CI: -3.92, -1.54). There were noticeable reductions in readmissions, mortality rates, and antibiotic prescriptions post antimicrobial stewardship multi-disciplinary team (AMS-MDT) interventions. Studies that involved a pharmacist as part of the AMS-MDT showed more significant improvement in measured outcomes than the studies that did not involve a pharmacist.

A Threshold Logistic Modelling Approach for Identifying Thresholds between Antibiotic Use and Methicillin-Resistant Staphylococcus aureus Incidence Rates in Hospitals

The aim of this study was to demonstrate the utility of threshold logistic modelling, an innovative approach in identifying thresholds and risk scores in the context of population antibiotic use associated with methicillin-resistant Staphylococcus aureus (MRSA) incidence rates in hospitals. The study also aimed to assess the impact of exceeding those thresholds that resulted in increased MRSA rates. The study was undertaken in a 700-bed hospital in England between January 2015 and December 2021 (84 monthly observations). By employing the threshold logistic modelling approach, we: (i) determined the cut-off percentile value of MRSA incidence that defines a critical level of MRSA; (ii) identified thresholds for fluoroquinolone and co-amoxiclav use that would accelerate MRSA incidence rates and increase the probability of reaching critical incidence levels; (iii) enabled a better understanding of the effect of antibiotic use on the probability of reaching a critical level of resistant pathogen incidence; (iv) developed a near real-time performance monitoring feedback system; (v) provided risk scores and alert signals for antibiotic use, with the ability to inform hospital policies, and control MRSA incidence; and (vi) provided recommendations and an example for the management of pathogen incidence in hospitals. Threshold logistic models can help hospitals determine quantitative targets for antibiotic usage and can also inform effective antimicrobial stewardship to control resistance in hospitals. Studies should work toward implementing and evaluating the proposed approach prospectively, with the aim of determining the best counter-measures to mitigate the risk of increased resistant pathogen incidence in hospitals.

Antimicrobial consumption in hospitalised COVID-19 patients: a systematic review and meta-analysis

Introduction

Despite COVID-19 being a viral illness, antibiotic use has been more prevalent. In addition, co-infection (3.5%) and secondary infection (14.3%) were relatively low in hospitalised patients with COVID-19. A major concern is the increased risk of antimicrobial resistance (AMR) due to inappropriate antibiotic consumption (1).

Aim

This review aims to evaluate antimicrobial consumption (excluding repurposed drugs such as remdesivir) in hospitals and determine the prevalence of COVID-19 patients who received antibiotic therapy using meta-analysis.

Methods

The review was conducted according to PRISMA guidelines (2). The two investigators independently developed and applied eligibility criteria to examine original articles. Studies were eligible for inclusion if they met the following criteria: (i) original research studies with a minimum sample of 50 patients; (ii) focussed on antibiotic consumption (AMC); (iii) patients with COVID-19 or consumption amid COVID-19 pandemic; (iv) any age group or gender; and (v) reported in the English language. The included articles were retrieved from MEDLINE, CINAHL, WHO COVID-19 databases, including studies published in EMBASE, Scopus, WHO-COVID, and LILACS between December 2019 to July 2021. The modified version of Newcastle-Ottawa Scale (NOS) was used to measure biases in included studies after the consensus by both authors. The random-effects model was used to estimate the pooled prevalence or proportion of AMC among hospitalized COVID-19 patients.

Results

A total of 34 studies conducted among hospitalised COVID-19 patients were included. The extracted studies presented AMC in defined daily doses (DDD) or frequency and percentages. Azithromycin was the most frequently prescribed antibiotic in almost all studies. The meta-analysis that examined overall AMC using data from 25 studies (17 studies from high income countries and eight from low-middle income countires) revealed 69% (95% CI:63%-74%) of hospitalized COVID-19 received at least one course of antibiotics. The sub-group analysis of studies from high income countries (HICs) revealed 59% (95% CI: 51%-66%) consumed antibiotics compared with 89% (95% CI: 82% to 94%) among hospitalised COVID-19 patients in low-middle income countries (LMICs).

Conclusion

This review highlights the trend of antibiotic consumption in hospitalised COVID-19 patients. A significant rise in antibiotic consumption was observed in LMICs and increased antibiotic consumption in the first few months of the COVID-19 pandemic in HIC. The review outcomes emphasised the importance of rational and judicious use of antimicrobial therapy as well as to strenghting the antimicrobial stewardship policies and activities, particularly during a global pandemic. The limitation of the review undertaken was not identified incidence of co-infection and don’t include studies on reported AMC in immunocompromised patients.

References

(1) Rawson TM, Ming D, Ahmad R, Moore LSP, Holmes AH. Antimicrobial use, drug-resistant infections and COVID-19. Nature reviews Microbiology. 2020;18(8):409-10.

(2) Beller EM, Glasziou PP, Altman DG, Hopewell S, Bastian H, Chalmers I, et al. PRISMA for Abstracts: Reporting Systematic Reviews in Journal and Conference Abstracts. PLOS Medicine. 2013;10(4):e1001419.

P14 Procalcitonin evaluation of antibiotic use in COVID-19 hospitalized patients during the first wave of COVID-19: the PEACH study

Background

A minority of patients presenting to hospital with COVID-19 have bacterial coinfection. Procalcitonin testing may help identify patients for whom antibiotics should be prescribed or withheld. The PEACH study describes the use of procalcitonin in English and Welsh hospitals during the first wave of the COVID-19 pandemic to help diagnose bacterial infections and guide antibiotic treatment. There is a lack of clear evidence to support its use in lung infections, which means in some hospitals, clinicians have used the procalcitonin test to guide antibiotic decisions in COVID-19, whilst in other hospitals, they have not. Our study is analysing data from hospitals that did and did not use procalcitonin testing during the first wave of the COVID-19 pandemic. It will determine whether and how procalcitonin testing should be used in the NHS in future waves of COVID-19 to protect patients from antibiotic overuse.

Methods

To assess whether the use of PCT testing, to guide antibiotic prescribing, safely reduced antibiotic use among patients who were hospitalized with COVID-19 during the first wave of the pandemic, we are answering this question through three different, and complimentary, work streams (WS), each with discrete work packages (WP): (i) Work Stream 1: utilization of PCT testing to guide antibiotic prescribing during the first wave of COVID-19 pandemic; (ii) Work Stream 2: patient-level impact of PCT testing on antibiotic exposure and clinical outcome (main work stream currently in analysis); and (iii) Work Stream 3: health economics analysis of PCT testing to guide antibiotics in COVID-19.

Results

Our first publication from Work Stream 1 (Antibiotics 2021, 10: 516) used a web-based survey to gather data from antimicrobial leads about the use of procalcitonin testing. Responses were received from 148/151 (98%) eligible hospitals. During the first wave of the COVID-19 pandemic, there was widespread introduction and expansion of PCT use in NHS hospitals. The number of hospitals using PCT in emergency/acute admissions rose from 17 (11%) to 74/146 (50.7%) and use in ICU increased from 70 (47.6%) to 124/147 (84.4%). This increase happened predominantly in March and April 2020, preceding NICE guidance. Approximately half of hospitals used PCT as a single test to guide decisions to discontinue antibiotics and half used repeated measurements. There was marked variation in the thresholds used for empirical antibiotic cessation and guidance about interpretation of values.

Conclusions

Procalcitonin testing has been widely adopted in the NHS during the COVID-19 pandemic in an unevidenced, heterogeneous way and in conflict with relevant NICE guidance. Further research is needed urgently that assesses the impact of this change on antibiotic prescribing and patient safety. Work Stream 2 is ongoing, and results will be published once available.

Pharmacists’ Knowledge, Attitudes, Behaviors and Information Sources on Antibiotic Use and Resistance in Jordan

Antimicrobial resistance (AMR) is a serious healthcare problem that affects public health globally. Appropriate understanding and knowledge of prudent antimicrobial use and resistance, along with providing evidence-based information sources, are needed for informed antibiotic prescribing practices. This study aimed to assess the knowledge, opportunity, motivation, behavior of pharmacists and their information sources regarding antibiotic use and resistance in Jordan. An online cross-sectional questionnaire was developed and administered to pharmacists during the period of July–September 2021. The survey is an adapted version of the validated European Centre for Disease Prevention and Control (ECDC) survey for antibiotic use and resistance. Pharmacists from all sectors (n = 384), of whom 276 (71.9%) were community pharmacists, completed an online questionnaire. While respondents scored highly (>87%) on knowledge on effective use, unnecessary use, and associated side effects of antibiotics, lower scores were recorded for knowledge on the spread of antibiotic resistance (52.9%). Pharmacists support easy access to guidelines on managing infections in 56% of cases, and easy access to materials advising prudent antibiotic use and resistance in 39.8% of cases. One-third of respondents (37.0%) reported no knowledge of any initiatives on antibiotic awareness and resistance. Pharmacists were aware (13.3%), unaware (36.2%), or unsure (50.5%) of the existence of a national antibiotic resistance action plan. Pharmacists indicated an interest in receiving more information on resistance to antibiotics (55.2%), medical conditions for which antibiotics are used (53.1%), how to use antibiotics (45.1%), prescribing of antibiotics (34.4%), and links between the health of humans, animals, and the environment (28.6%). Findings can inform antimicrobial stewardship with required interventions to improve antibiotic use.

Antimicrobial consumption in patients with COVID-19: a systematic review and meta-analysis

INTRODUCTION

Since the onset of the pandemic, prescribing antimicrobials has become a common practice to treat patients infected with COVID-19.

AREAS COVERED

A systematic literature search was performed in the electronic databases MEDLINE, CINAHL, WHO COVID-19 database, including EMBASE, Scopus, WHO-COVID, LILACS, and Google Scholar to identify original articles published up to 31 July 2021. A random-effects model was used to estimate the pooled prevalence or proportion of antimicrobial consumption among COVID-19 patients.

EXPERT OPINION

We identified 43 original articles, 33 studies from high-income countries, six from upper-middle-income countries, and four from lower-middle-income countries. Most of the studies presented data from hospital or secondary health-care settings (n = 34). Included studies measured antimicrobial consumption as Daily Defined Doses (DDD) or day of therapy (DOT) or percentage. A total of 19 studies measured antimicrobial consumption as DDDs or DOT. Meta-analysis revealed an overall high antimicrobial consumption of 68% (95% CI: 60% to 75%). The subgroup analysis found a lower consumption in high-income countries (58%, 95% CI: 48% to 67%), compared with lower and middle-income countries (89%, 95% CI: 82% to 94%). High antimicrobial consumption found in COVID-19 patients demands implementation of appropriate antimicrobial stewardship interventions.

Use of Procalcitonin during the First Wave of COVID-19 in the Acute NHS Hospitals: A Retrospective Observational Study

A minority of patients presenting to hospital with COVID-19 have bacterial co-infection. Procalcitonin testing may help identify patients for whom antibiotics should be prescribed or withheld. This study describes the use of procalcitonin in English and Welsh hospitals during the first wave of the COVID-19 pandemic. A web-based survey of antimicrobial leads gathered data about the use of procalcitonin testing. Responses were received from 148/151 (98%) eligible hospitals. During the first wave of the COVID-19 pandemic, there was widespread introduction and expansion of PCT use in NHS hospitals. The number of hospitals using PCT in emergency/acute admissions rose from 17 (11%) to 74/146 (50.7%) and use in Intensive Care Units (ICU) increased from 70 (47.6%) to 124/147 (84.4%). This increase happened predominantly in March and April 2020, preceding NICE guidance. Approximately half of hospitals used PCT as a single test to guide decisions to discontinue antibiotics and half used repeated measurements. There was marked variation in the thresholds used for empiric antibiotic cessation and guidance about interpretation of values. Procalcitonin testing has been widely adopted in the NHS during the COVID-19 pandemic in an unevidenced, heterogeneous way and in conflict with relevant NICE guidance. Further research is needed urgently that assesses the impact of this change on antibiotic prescribing and patient safety.

Outcomes of multisite antimicrobial stewardship programme implementation with a shared clinical decision support system

Background

Studies evaluating antimicrobial stewardship programmes (ASPs) supported by computerized clinical decision support systems (CDSSs) have predominantly been conducted in single site metropolitan hospitals.

Objectives

To examine outcomes of multisite ASP implementation supported by a centrally deployed CDSS.

Methods

An interrupted time series study was conducted across five hospitals in New South Wales, Australia, from 2010 to 2014. Outcomes analysed were: effect of the intervention on targeted antimicrobial use, antimicrobial costs and healthcare-associated Clostridium difficile infection (HCA-CDI) rates. Infection-related length of stay (LOS) and standardized mortality ratios (SMRs) were also assessed.

Results

Post-intervention, antimicrobials targeted for increased use rose from 223 to 293 defined daily doses (DDDs)/1000 occupied bed days (OBDs)/month (+32%, P  <   0.01). Conversely, antimicrobials targeted for decreased use fell from 254 to 196 DDDs/1000 OBDs/month (-23%; P  <   0.01). These effects diminished over time. Antimicrobial costs decreased initially (-AUD$64551/month; P  <   0.01), then increased (+AUD$7273/month; P  <   0.01). HCA-CDI rates decreased post-intervention (-0.2 cases/10 000 OBDs/month; P  <   0.01). Proportional LOS reductions for key infections (respiratory from 4.8 to 4.3 days, P  <   0.01; septicaemia 6.8 to 6.1 days, P  <   0.01) were similar to background LOS reductions (2.1 to 1.9 days). Similarly, infection-related SMRs (observed/expected deaths) decreased (respiratory from 1.1 to 0.75; septicaemia 1.25 to 0.8; background rate 1.19 to 0.90.

Conclusions

Implementation of a collaborative multisite ASP supported by a centrally deployed CDSS was associated with changes in targeted antimicrobial use, decreased antimicrobial costs, decreased HCA-CDI rates, and no observable increase in LOS or mortality. Ongoing targeted interventions are suggested to promote sustainability.

Impact of an antimicrobial stewardship intervention on appropriateness of prescribing for community-acquired pneumonia in an Australian regional hospital

Community-acquired pneumonia (CAP) is the second commonest indication for antibiotic use in Australian hospitals and is therefore a frequent target for antimicrobial stewardship. A single-centre prospective study was conducted in a regional referral hospital comparing management of adult patients with CAP before and after an educational intervention. We demonstrated a reduction in duration of therapy and reduced inappropriate use of ceftriaxone-based regimens for non-severe CAP.

Discontinuation of peri-operative gentamicin use for indwelling urinary catheter manipulation in orthopaedic surgery

BACKGROUND

Gentamicin has historically been used prior to insertion and removal of indwelling urinary catheters (IDCs) around elective joint replacement surgery to prevent infection; however, this indication is not recognized in the Australian Therapeutic Guidelines: Antibiotic and the paradigm for safe use of gentamicin has shifted.

METHODS

The antimicrobial stewardship team of a 500 bed tertiary regional hospital performed a retrospective clinical study of gentamicin IDC prophylaxis around total hip and knee arthroplasties. Results were presented to the orthopaedic surgeons. A literature review identified no guidelines to support gentamicin prophylaxis and only a very low risk of bacteraemia associated with IDC insertion/removal in patients with established bacteriuria. Consensus was reached with the surgeons to discontinue this practice. Subsequent prospective data collection was commenced to determine effectiveness, with weekly feedback to the Department Head of Orthopaedics.

RESULTS

Data from 137 operations pre-intervention (6 months) were compared with 205 operations post-intervention (12 months). The median patient age was 72 years in both groups. Following the intervention, reductions in gentamicin use were demonstrated for IDC insertion (59/137 (42%) to 4/205 (2%), P < 0.01) and removal (39/137 (28%) to 6/205 (3%), P < 0.01). No gentamicin use was observed during the final 40 weeks of the post-intervention period. There were no significant differences between the groups for pre-operative bacteriuria, surgical site infections or acute kidney injury.

CONCLUSION

A collaborative approach using quality improvement methodology can lead to an evidence-based reappraisal of established practice. Regular rolling audits and timely feedback were useful in sustaining change.

Reconstruction of the temporomandibular joint by the transfer of the free vascularised second metatarsal

We present our experience of a series of patients who presented for salvage reconstruction of the temporomandibular joint (TMJ) for relief of pain. Reconstruction was achieved by transfer of the free vascularised second metatarsal. This technique has been used for a total of seven TMJ reconstructions in five patients. We describe the surgical anatomy, technique and results during the last 18 years. One joint failed but the other six surviving joints continue to provide adequate pain-free function. We advocate this technique for autogenous salvage reconstruction in joints that have been previously operated on unsuccessfully.

Castleman's disease presenting as a midline neck mass

We report the case of a 13-year-old girl who presented with a painless midline submental mass. Excision biopsy confirmed Castleman's disease of the hyaline-vascular type. This unusual condition needs to be considered in the differential diagnosis of masses arising in the neck.

Repair of secondary aortoesophageal fistula by endoluminal stent-grafting

PURPOSE

To describe a case of secondary aortoesophageal fistula that was treated with an endoluminal stent-graft.

CASE REPORT

A 58-year-old woman presented with hematemesis and melena. In 1974 she had an interposition graft repair of an aortic transection sustained during a traffic accident. At the examination in 1998, angiography demonstrated a mechanical disruption of the proximal anastomosis forming an aortoesophageal fistula. A 28-mm x 3.75-cm AneuRx stent-graft was introduced via a right femoral arteriotomy and deployed across the defect. Follow-up CT scans at 18 months showed exclusion of the false aneurysm with no evidence of infection; the patient remains well at >2 years after stent-graft implantation.

CONCLUSIONS

Endoluminal repair can be successful in achieving a satisfactory midterm outcome in cases of secondary aortoesophageal fistula.

Multiple aneurysms associated with congenital rubella

We describe the case of a woman with congenital rubella who presented with backache. Plain abdominal X-ray revealed calcification of a superior mesenteric artery aneurysm. Intra-arterial digital subtraction angiography demonstrated multiple aneurysms of the arteries to the upper and lower limbs and the viscera. We have not found another report in the literature of the association of congenital rubella with multiple aneurysms.

A phase I/II study of vinorelbine, doxorubicin, and methotrexate with leucovorin rescue as first-line treatment for metastatic breast cancer

PURPOSE

This study was performed to determine the maximum tolerated dose (MTD) and toxicity of vinorelbine when used in combination with doxorubicin and methotrexate with leucovorin rescue in women with metastatic breast cancer.

METHODS

Enrolled in the study were 23 women with metastatic breast cancer who had not received prior chemotherapy for metastatic disease. Patients treated at the first dose level received vinorelbine 20 mg/m2 on day 1, doxorubicin 40 mg/m2 on day 1, methotrexate 100 mg/m2 on day 1 and leucovorin 20 mg orally every 6 h for six doses beginning on day 2. Treatment was repeated every 21 days. The vinorelbine dose was escalated by 5 mg/m2 for patients treated at subsequent dose levels. The MTD was defined as the dose level at which fewer than one-third of patients enrolled experienced dose-limiting toxicity (DLT). When the MTD of vinorelbine had been determined, the doxorubicin dose was then escalated by 10 mg/m2 with the vinorelbine dose held at its MTD.

RESULTS

total of 98 courses of treatment (median of 4 per patient, range 2-8) were administered. The MTD of this regimen was found to be vinorelbine 25 mg/m2, doxorubicin 40 mg/m2, and methotrexate 100 mg/m2 with leucovorin rescue. At higher doses of vinorelbine, neutropenia, fatigue, arm pain, malaise, nausea and vomiting were dose-limiting. Higher doses of doxorubicin resulted in universal dose limiting neutropenia, and frequent nonhematologic DLT consisting of arm pain, malaise, stomatitis, nausea and vomiting. Amongst the 20 patients with measurable disease, there were 3 complete responses (15%, 95% confidence interval 3%-38%), 5 partial responses (25%, 95% confidence interval 9%-49%) and an overall response rate of 40% (95% confidence interval 19%-64%). The median survival was estimated to be 25 months from the start of chemotherapy.

CONCLUSIONS

Vinorelbine at 25 mg/m2 can be safely administered with doxorubicin at 40 mg/m2 and methotrexate at 100 mg/m2 with leucovorin rescue. Response rates observed with this regimen suggest that this combination of chemotherapeutic agents may not be more effective than the combination of vinorelbine and doxorubicin.

Inhibition of PAF-induced human platelet aggregation by antithrombotic nipecotomides

Nipecotamides (piperidine-3-carboxamides) are potent inhibitors of platelet aggregation induced by a variety of agonists in vitro and in vivo. The inhibitory effects of six structural types of nipecotamides on human platelet aggregation induced by platelet-activating factor (PAF) in vitro, are studied. Evaluation of 15 racemates and stereoisomers of two nipecotamides showed that bis-nipecotoyl alkanes were more active than their mono congeners. Mono- and bis-nipecotoyl decanes were more potent than the corresponding hexanes. Lipophilicity was found to play a significant role in the antiplatelet activity of these compounds. The stereoselectivity in the PAF-antagonist potential of nipecotamides was less pronounced than that resulting from their action on ADP- or collagen-induced aggregation. Oxidation of the two benzylic carbon atoms of alpha, alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene.2HBr (A-1) to form 1,4-bis[3-N,N-diethylcarbamoyl) piperidino]benzenedicarboxamide (A-40K), which has a second set of carbonyl oxygens but lacks basic N atoms, resulted in a remarkable loss of ADP-antagonist potency while retaining PAF-antagonist activity. It is suggested that in addition to their membrane effects, nipecotamides act at other sites, including the PAF receptor. Double reciprocal plots of PAF binding to gel-filtered platelets (GFP) in the presence and absence of a typical nipecotamide (A-1C) were indicative of competitive inhibition (Ki = 19.28 microM). Scatchard analysis of 3H-PAF binding to GFP suggested the presence of high, intermediate (I) and low affinity binding sites, of which the I site gave a KD/app of 0.332 nM with an estimated 564 sites/platelet. Key interactions of nipecotamides with the PAF receptor appear to be the following (i) electrostatic interactions of the two amide oxygens with a primary set of electropositive areas spaced at 5-7 A, (ii) in the case of appropriate compounds, electrostatic interactions of the two amide oxygens spaced at 10-12 A with corresponding secondary receptor sites carrying positive electrostatic potential, (iii) a hydrophobic moiety fitting into a hydrophobic pocket in the receptor, and (iv) the cationic piperidine N+ (at pH 7.4) interacting with a counterion, probably aspartic acid.

Design and synthesis of piperidine-3-carboxamides as human platelet aggregation inhibitors

A detailed structure-activity analysis was carried out using eight 1-alkyl(aralkyl)nipecotamides (type 5), 33 bis-nipecotamidoalkanes and aralkanes (type 6), and 7 N,N'-bis(nipecotoyl)-piperazines (type 7) as inhibitors of human platelet aggregation. Steric factors played an important role in determining the activity of type 5 compounds possessing an an appropriate degree of hydrophobic character. Types 6 and 7 compounds were more potent than the corresponding type 5 molecules. Hydrophobic character appeared to influence the activity of type 6 compounds. A 3-substituent on the piperidine ring was necessary for antiplatelet activity; the substituent should be preferably an amide with its C attached directly to the ring. 3,5-Disubstitution and 2-substitution led to a decline in activity. Optimal activity was attained when the two nipecotoyl ring N atoms were connected by an aralkyl group, and separated by approximately 7 A. It is suggested that van der Waals forces and pi interactions may govern the inhibitor-platelet interaction. The most potent type 6 inhibitor was alpha,alpha'-bis[3-(N-ethyl-N-butylcarbamoyl)piperidino]-p-xylene (6i). The most potent type 5 compound was 1-decyl-3-(N,N-diethylcarbamoyl)piperidine (5a). Any substitution on the piperazine ring of type 7 compounds led to a decline in activity, the most active analog being N,N'-bis(1-decylnipecotoyl)piperazine (7a). It is suggested that nipecotamides interact with anionic platelet sites located 7 A from each other and connected by a hydrophobic well.

Synergistic antiplatelet effects of a nipecotamide A-1C and low dose aspirin

1. The effects of an antithrombotic nipecotamide, A-1, and aspirin were examined separately and in combination, on human platelet aggregation in vitro and on collagen+epinephrine-induced thromboembolic death of mice in vivo. 2. Concurrent addition of the two agents to a platelet suspension resulted in a supraadditive inhibition. Racemic A-1 and its meso diastereomer A-1C behaved similarly in this respect. The IC50 value of rac. A-1 declined from 46.25 to 18.4 microM in the presence of aspirin. 3. In vivo, concurrent administration of A-1C and aspirin produced significant potentiation of antithrombotic activity. A 2-fold reduction in the ED50 of A-1C occurred when it was coadministered with aspirin to mice; also, the toxicity reduced slightly, increasing the therapeutic index by a factor of 2.2. 4. The design and synthesis of new compounds possessing the structural features of the two molecules appears to provide superior antithrombotic agents.

Inhibition of agonist-induced rise in platelet Ca2+ by antithrombotic nipecotamides

The effects of three structural types of nipecotamides and their stereoisomers on collagen-induced aggregation and intraplatelet ionized calcium ([Ca2+]i) rise in human platelets were evaluated using aequorin as the [Ca2+]i indicator. The orders of potencies of racemic nipecotamides were different when collagen was the agonist compared with those obtained using ADP. It is suggested that in addition to their earlier hypothesized interactions with platelet anionic phospholipids of the plasma and organelle membranes, nipecotamides may, in addition, act at other receptor sites. In general, the inhibition of collagen-induced aggregation paralleled their inhibitory effects on the rise of [Ca2+]i. The compounds were stereoselective in inhibiting aggregation as well as [Ca2+]i rise. The meso diastereomers of I and II were more potent than the corresponding enantiomeric pairs. A single [Ca2+]i peak was noticed when the incubate contained 1.0 mM extracellular calcium [Ca2+]o. On the other hand a biphasic [Ca2+]i rise was noticed when the nominally Ca(2+)-free buffer contained 75 microM ethylene glycol tetraacetate (EGTA). The first peak corresponded with platelet shape change, suggesting Ca2+ discharge from internal stores, and the second, with aggregation. The second peak may reflect either Ca2+ flux across the plasma membrane or aequorin leak from internal cellular locations or from the canicular system. Inhibition of the rise in intraplatelet Ca2+ appears to be associated with the platelet aggregation-inhibitory actions of nipecotamides.

Enantioselective antiplatelet actions of nipecotamides

Two synthetic racemic nipecotamides, 1-decyl-3-(N,N- diethylcarbamoyl)piperidine hydrobromide (1) and alpha, alpha'-bis[3-(N-benzyl-N-methylcarbamoyl)piperidino]-p-xylene dihydrobromide (2) were resolved on a chiral alpha 1-acid glycoprotein semipreparative HPLC column. Thus, rac.1 was resolved into two enantiomers 1A-(+) and 1B-(-); rac.2 was separated into the optical antipodes 2A-(-) and 2C-(+), and the meso diastereomer 2B-(0). Also on a preparative scale, 97% pure 2C was obtained via diastereomeric salt formation using dibenzoyl-L-(-)-tartaric acid. The individual isomers were evaluated for their platelet aggregation inhibitory potency. In inhibiting ADP-induced aggregation of human platelets in vitro, 1B-(-) was 4 times more potent than its optical antipode 1A-(+), and 2C-(+) was 6 times as active as 2A-(-); the meso diastereomer 2B-(0) had intermediate activity. With collagen as the 1B-(-) was twice as active as 1A-(+), and 2C-(+), the most active compound in this series (IC50 = 0.96 microM), was 10 times more potent than its antipode 2A-(-). Again, the meso diastereomer 2B-(0) had intermediate activity. These results demonstrate the enantioselective antiplatelet actions of mono- and bis- nipecotamide derivatives.

In vitro and in vivo activities of the novel antiplatelet agent alpha,alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene dihydrobromide

In an effort to develop compounds with high antithrombotic activity and minimal toxicity, our laboratory has synthesized a number of nipecotamides. The effectiveness of one of these compounds, alpha,alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene dihydrobromide (A-1), in inhibiting both in vitro and in vivo platelet aggregation is reported here, along with its acute toxicity. The IC50 of A-1 in in vitro ADP- and PAF-induced platelet aggregation was 44.5 microM and 21.2 microM, respectively. Suppression of intraplatelet [Ca2+] is suggested as a likely mediator of the aggregation-inhibitory properties of A-1, since both the release of cytosolic Ca2+ and the influx of extracellular Ca2+ were decreased. The ED50 of A-1 in protecting mice against thromboembolism induced by a collagen-epinephrine challenge was 164 mumol/kg. The measurement of the acute toxicity of this compound as the LD50 was 691 mumol/kg, with the therapeutic index being 4.2. These data indicate that compounds in this family hold promise as clinically effective antithrombotic agents.

Molecular determinants of the platelet aggregation inhibitory activity of carbamoylpiperidines

A series of alpha,alpha'-bis[3-(N,N-dialkylcarbamoyl)piperidino]-p- xylenes were synthesized and tested for their inhibitory activity on ADP-induced aggregation of human platelets. A parabolic curve was obtained when log 1/C (activity) was plotted against log P (octanol/water partition coefficient). Using this as a model, a new analogue, alpha,alpha'-bis-[3-(N-methyl-N-butylcarbamoyl)piperidino]-p-xylen e (3g), was synthesized with a predicted IC50 of 25 microM. When this compound was subsequently evaluated, the IC50 was 22.1 +/- 5.5 microM, demonstrating the applicability of this model. The amide oxygen of the carbamoyl substituent appeared necessary for activity. Thus, for example, when the amide carbonyl group of 3a (IC50 = 44.5 microM) was reduced to CH2, the resulting compound 4 had a dramatically reduced activity, IC50 = 1565 microM. Compound 3a was resolved into (+) and (-) enantiomers and a meso (0) diastereomer using fractional crystallization, diastereomeric tartrate formation, and chiral HPLC. Compared to (-)-3a, the (+) isomer was 15 times more potent when ADP was the agonist and 19 times more active when collagen was used as the agonist. Molecular modeling of R,R- and S,S-3a using the SYBYL program was used to examine their interactions with phosphatidylinositol (PI). There was a better fit between PI and the R,R-3a with the energy of interaction being 17.6 kcal/mol less than that of the S,S-3a/PI complex. Although the absolute stereochemistry of individual enantiomers is not known, this study shows that R,R-3a interacts more favorably with PI than does S,S-3a and that (+)-3a is a more potent inhibitor of human platelet aggregation than (-)-3a. It is postulated that because of their lipophilicity, these compounds penetrate the platelet membrane and are then protonated at the pH of the cytosol. The protonated N then neutralizes the anionic charge on the membrane phosphoinositides, thereby rendering them less susceptible to hydrolysis by phospholipase C. Thus, the determinant parameters for optimum antiplatelet activity in 3-carbamoylpiperidines are (1) the amide carbonyl, (2) appropriate stereochemistry of the 3-substituent and (3) a log P value of about 4.5.

Cytosolic ionized calcium in human platelets: the influence of collagen and a novel antiplatelet agent

Two phases of calcium mobilization were observed when aequorin-loaded human platelets, suspended in a nominally calcium-free medium containing 0.1 mM EGTA, were stimulated with collagen. The first phase coincided with platelet shape change, and the second phase corresponded to aggregation. On the other hand, only one [Ca2+]i peak was found in systems containing 1.0 mM Ca, or 1.0 or 2.0 mM EGTA. A novel antiplatelet compound alpha,alpha'-bis [3-(N,N-diethylcarbamoyl)piperidino]-p-xylene dihydrobromide, inhibited both [Ca2+]i peaks. It is suggested that inhibition of the mobilization of intraplatelet calcium stores as well as the blocking of transmembrane calcium flux may be responsible for the platelet aggregation-inhibitory action of this compound.

The effect of carbamoylpiperidine and nipecotoylpiperazine analogs on ADP-stimulated human thrombocyte aggregation and platelet factor 3 availability

There is a striking congruence between the inhibitory effects of three synthetic entities on ADP-induced (i) human blood platelet aggregation and (ii) platelet factor 3 availability as evidenced by prolonged 'Stypven time'. The pronounced parallel between each compound's potency in inhibiting aggregation (e.g. IA 48.9 +/- 1.3, S.E., %; n = 16) and in impeding platelet factor 3 availability (e.g. IPF-3av 42.3 +/- 2.5, S.E., %; n = 12), determined concurrently in platelet-rich plasma of four different donors, further substantiates that the antiplatelet activity of our carbamoylpiperidine and nipecotoylpiperazine congeners is exerted through their interaction with anionic phospholipids.

Some novel inhibitors of platelet aggregation: acute toxicity in mice and its relationship to in vitro efficacy and toxicity. II. Nipecotoylaminoalkane and nipecotoylpiperazine congeners

Four closely related nipecotoyl congeners are employed as molecular probes to evaluate the effects of systematic molecular changes upon lethal potency of the compounds. The in vivo toxicities, effected by changes in molecular structure, are compared to their in vitro concentrations inhibiting ADP-induced aggregation and epinephrine-induced primary aggregation of human blood platelets and their toxicities to mouse fibroblasts (L-929 cells) in culture. To assist in the selection of compounds which offer the greatest promise as therapeutic agents for further evaluation and to guide future development of optimal molecular structures, a ratio of acute ip LD50 (mumol/kg) [Tm] to concentration inhibiting 50% ADP-induced platelet aggregation (mumol/liter) [A] is calculated for each compound. These ratios range from 2.41 to 24.92 for the four compounds included in this study.

Relationships between chemical structure and inhibition of epinephrine-induced human blood platelet aggregation

The effect of structural features in a series of carbamoylpiperidine and nipecotoylpiperazine congeners on epinephrine-induced aggregation of human blood platelets is examined. Epinephrine-induced primary aggregation is effectively inhibited by the nipecotoylpiperazine derivatives (culminating at an IPA50 of 11.9 microM). While among nipecotoylpiperazine as well as carbamoylpiperidine congeners there are potent inhibitors of ADP-stimulated platelet function (cresting at an IA50 of 12.4 and 11.4 microM, respectively), the carbamoylpiperidine analogs are much less active (e.g., IPA50 of 298.1), or practically inactive, in impeding epinephrine-induced primary aggregation (PA).

Relationships between chemical structure and inhibition of ADP-stimulated human thrombocyte release of serotonin and platelet factor 4

The inhibitory potencies of carbamoylpiperidinoalkane and N-alkylnipecotoylpiperazine derivatives on ADP-stimulated human blood platelet aggregation, serotonin (5-HT) release and platelet factor 4 (PF-4) release were evaluated. The procedure was designed to allow concurrent determination of all three sets of values. Most compounds were more than twice as potent in blocking PF-4 (X = 91 +/- 1 (S.E., n = 7)%) compared to their inhibition of 5-HT (X = 38 +/- 1(S.E., n = 6)%) release; the one compound which failed to meet these criteria was still decidedly more powerful in impeding PF-4 than 5-HT release. Since the compounds' platelet aggregation-inhibitory values were within the same range as their 5-HT release-blocking potencies, but had a strikingly greater impact in arresting PF-4 release, it is suggested that the platelet plasma membrane and the lining enveloping the dense bodies may share certain commonalities, while the sheathing encasing the alpha-granules may differ from both in a tangible manner.