Physician antimicrobial prescribing and patient outcomes on general medical wards: a multicentre retrospective cohort study.

BACKGROUND: Variability in antimicrobial prescribing may indicate an opportunity for improvement in antimicrobial use. We sought to measure physician-level antimicrobial prescribing in adult general medical wards, assess the contribution of patient-level factors to antimicrobial prescribing and evaluate the association between antimicrobial prescribing and clinical outcomes. METHODS: Using the General Medicine Inpatient Initiative (GEMINI) database, we conducted a retrospective cohort study of physician-level volume and spectrum of antimicrobial prescribing in adult general medical wards in 4 academic teaching hospitals in Toronto, Ontario, between April 2010 and December 2019. We stratified physicians into quartiles by hospital site based on volume of antimicrobial prescribing (days of therapy per 100 patient-days and antimicrobial-free days) and antibacterial spectrum (modified spectrum score). The modified spectrum score assigns a value to each antibacterial agent based on the breadth of coverage. We assessed patient-level differences among physician quartiles using age, sex, Laboratory-based Acute Physiology Score, discharge diagnosis and Charlson Comorbidity Index. We evaluated the association of clinical outcomes (in-hospital 30-day mortality, length of stay, intensive care unit [ICU] transfer and hospital readmission) with antimicrobial volume and spectrum using multilevel modelling. RESULTS: The cohort consisted of 124 physicians responsible for 124 158 hospital admissions. The median physician-level volume of antimicrobial prescribing was 56.1 (interquartile range 51.7-67.5) days of therapy per 100 patient-days. We did not find any differences in baseline patient characteristics by physician prescribing quartile. The difference in mean prescribing between quartile 4 and quartile 1 was 15.8 days of therapy per 100 patient-days (95% confidence interval [CI] 9.6-22.0), representing 30% higher antimicrobial prescribing in the fourth quartile than the first quartile. Patient in-hospital deaths, length of stay, ICU transfer and hospital readmission did not differ by physician quartile. In-hospital mortality was higher among patients cared for by prescribers with higher modified spectrum scores (odds ratio 1.13, 95% CI 1.04-1.24). INTERPRETATION: We found that physician-level variability in antimicrobial prescribing was not associated with differences in patient characteristics or outcomes in academic general medicine wards. These findings provide support for considering the lowest quartile of physician antimicrobial prescribing within each hospital as a target for antimicrobial stewardship.

Vancomycin Therapeutic Drug Monitoring: A Cross-Sectional Survey of Canadian Hospitals.

Background: Little is known about the current landscape of vancomycin therapeutic drug monitoring (TDM) in Canadian hospitals, which operate within publicly funded health care systems. Objectives: To determine current TDM practices for vancomycin and associated challenges and to gather perceptions about TDM based on area under the concentration-time curve (AUC) in Canadian hospitals. Methods: An electronic survey was distributed to hospital pharmacists in spring 2021 through multiple national and provincial antimicrobial stewardship, public health, and pharmacy organizations. The survey gathered data about hospital characteristics, TDM methods, inclusion criteria for patient selection, pharmacokinetic and pharmacodynamic targets, vancomycin susceptibility testing and reporting, and perceived barriers and challenges. Results: In total, 120 pharmacists from 10 of the 13 provincial and territorial jurisdictions in Canada, representing 12.5% of Canadian acute care hospitals (n = 962), completed at least 90% of survey questions. The predominant TDM method was trough-based (107/119, 89.9%); another 10.1% of respondents (12/119) reported performing AUC-based TDM (with or without trough-based TDM), and 17.9% (19/106) of those not already using AUC-based TDM were considering implementing it within 1 to 2 years. Among hospitals performing trough-based TDM, 60.5% (66/109) targeted trough levels between 15 and 20 mg/L for serious infections with methicillin-resistant Staphylococcus aureus. One-quarter of the respondents using this method (27/109, 24.8%) agreed that trough-based TDM was of uncertain benefit, and about one-third (33/109, 30.3%) were neutral on this question. Multiple challenges were identified for trough-based TDM, including sub- or supra-therapeutic concentrations and collection of specimens at inappropriate times. Overall, 40.5% (47/116) of respondents agreed that AUC-based TDM was likely safer than trough-based TDM, whereas 23.3% (27/116) agreed that AUC-based TDM was likely more effective. Conclusions: This survey represents a first step in developing evidence-based, standardized best practices for vancomycin TDM that are uniquely suited to the Canadian health care system.

Contexte: On connaît peu de choses sur le paysage actuel du suivi thérapeutique pharmacologique (STP) de la vancomycine dans les hôpitaux canadiens, dont les activités s'inscrivent dans le cadre des systèmes de soins de santé financés par les deniers publics. Objectifs: Déterminer les pratiques actuelles de STP de la vancomycine et les défis associés et recueillir les perceptions concernant le STP sur la base de l'aire sous la courbe de la concentration en fonction du temps (ASC) dans les hôpitaux canadiens. Méthodes: Un sondage a été distribué électroniquement aux pharmaciens d'hôpitaux au printemps 2021 par plusieurs organismes nationaux et provinciaux de gestion de l'utilisation des antimicrobiens, de santé publique et de pharmacie. Le sondage a permis de rassembler des données concernant les caractéristiques des hôpitaux, les méthodes de STP, les critères d'inclusion pour la sélection des patients, les objectifs pharmacocinétiques et pharmacodynamiques, les tests de sensibilité à la vancomycine et les rapports des résultats, ainsi que les obstacles et les défis perçus. Résultats: Au total, 120 pharmaciens de 10 des 13 provinces et territoires du Canada, représentant 12,5 % des hôpitaux canadiens de soins actifs (n = 962), ont répondu à au moins 90 % des questions du sondage. La méthode de STP prédominante utilisée était celle de la concentration minimale (107/119, 89,9 %); un autre 10,1 % des répondants (12/119) ont déclaré effectuer un STP basé sur l'ASC (avec ou sans STP basé sur la concentration minimale), et 17,9 % (19/106) de ceux qui n'effectuaient pas déjà le STP basé sur l'ASC envisageaient de le mettre en œuvre d'ici 1 à 2 ans. Parmi les hôpitaux pratiquant le STP basé sur la concentration minimale, 60,5 % (66/109) ciblaient des concentrations minimales entre 15 et 20 mg/L pour les infections graves à Staphylococcus aureus résistant à la méthicilline. Un quart des répondants qui utilisaient cette méthode (27/109, 24,8 %) convenaient que les avantages du STP basé sur la concentration minimale étaient incertains, et environ un tiers (33/109, 30,3 %) étaient neutres. De multiples défis ont été identifiés pour le STP basé sur la concentration minimale, notamment des concentrations sous-ou supra-thérapeutiques et la collecte d'échantillons à des moments inappropriés. Dans l'ensemble, 40,5 % (47/116) des répondants convenaient que le STP basé sur l'ASC était probablement plus sûr que le STP basé sur la concentration minimale, tandis que 23,3 % (27/116) convenaient que le STP basé sur l'ASC était probablement plus efficace. Conclusions: Ce sondage représente une première étape dans l'élaboration de pratiques exemplaires normalisées et fondées sur des données probantes pour le STP de la vancomycine qui sont particulièrement adaptées au système de santé canadien.

Cardiovascular Event Reporting in Modern Cancer Radiation Therapy Trials.

PURPOSE: Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in cancer survivors, particularly after chest radiation therapy (RT). However, the extent to which CVD events are consistently reported in contemporary prospective trials is unknown. METHODS AND MATERIALS: From 10 high-impact RT, oncology, and medicine journals, we identified all latter phase trials from 2000 to 2019 enrolling patients with breast, lung, lymphoma, mesothelioma, or esophageal cancer wherein chest-RT was delivered. The primary outcome was the report of major adverse cardiac events (MACEs), defined as incident myocardial infarction, heart failure, coronary revascularization, arrhythmia, stroke, or CVD death across treatment arms. The secondary outcome was the report of any CVD event. Multivariable regression was used to identify factors associated with CVD reporting. Pooled annualized incidence rates of MACEs across RT trials were compared with contemporary population rates using relative risks (RRs). RESULTS: The 108 trials that met criteria enrolled 59,070 patients (mean age, 58.0 ± 10.2 years; 46.0% female), with 273,587 person-years of available follow-up. During a median follow-up of 48 months, 468 MACEs were reported (including 96 heart failures, 75 acute coronary syndrome, 1 revascularization, 94 arrhythmias, 28 strokes, and 20 CVD deaths; 307 occurred in the intervention arms vs 144 in the control arms; RR, 1.96; P < .001). Altogether, 50.0% of trials did not report MACEs, and 37.0% did not report any CVD. The overall weighted-trial incidence was 376 events per 100,000 person-years compared with 1408 events per 100,000 person-years in similar nontrial patients (RR, 0.27; P < .001). There were no RT factors associated with CVD reporting. CONCLUSION: In contemporary chest RT-based clinical trials, reported CVD rates were lower than expected population rates.

Adrenocortical Carcinoma Discovered with Point-of-care Ultrasound.

CASE PRESENTATION: A 34-year-old woman presented to the emergency department with bilateral lower extremity edema and shortness of breath. She had been seen by her primary care provider. Lab work and a follow-up with endocrinology had been unrevealing. Using point-of-care ultrasound we identified a cystic mass in the right upper quadrant prompting further imaging. DISCUSSION: Abdominal and pelvic computed tomography confirmed a mass in the right posterior liver, which was later identified as an adrenocortical carcinoma. Ultrasound is an important diagnostic tool in the setting of lower extremity edema and can be used to assess for heart failure, liver failure, obstructive nephropathy, venous thrombosis, and soft tissue infection. In this case, ultrasound helped expedite the diagnosis and treatment of a rare malignancy.

Community pharmacist prescribing of antimicrobials: A systematic review from an antimicrobial stewardship perspective.

BACKGROUND: Pharmacist prescribing authority is expanding, while antimicrobial resistance is an increasing global concern. We sought to synthesize the evidence for antimicrobial prescribing by community pharmacists to identify opportunities to advance antimicrobial stewardship in this setting. METHODS: We conducted a systematic review to characterize the existing literature on community pharmacist prescribing of systemic antimicrobials. We searched MEDLINE, EMBASE and International Pharmaceutical Abstracts for English-language articles published between 1999 and June 20, 2019, as well as hand-searched reference lists of included articles and incorporated expert suggestions. RESULTS: Of 3793 articles identified, 14 met inclusion criteria. Pharmacists are most often prescribing for uncomplicated urinary tract infection (UTI), acute pharyngitis and cold sores using independent and supplementary prescribing models. This was associated with high rates of clinical improvement (4 studies), low rates of retreatment and adverse effects (3 studies) and decreased health care utilization (7 studies). Patients were highly satisfied (8 studies) and accessed care sooner or more easily (7 studies). Seven studies incorporated antimicrobial stewardship into study design, and there was overlap between study outcomes and those relevant to outpatient antimicrobial stewardship. Pharmacist intervention reduced unnecessary prescribing for acute pharyngitis (2 studies) and increased the appropriateness of prescribing for UTI (3 studies). CONCLUSION: There is growing evidence to support the role of community pharmacists in antimicrobial prescribing. Future research should explore additional opportunities for pharmacist antimicrobial prescribing and ways to further integrate advanced antimicrobial stewardship strategies in the community setting. Can Pharm J (Ott) 2021;154:xx-xx.

Development and evaluation of a primary care antimicrobial stewardship program (PC-ASP) in Toronto, Ontario, Canada.

Background: Effective community-based antimicrobial stewardship programs (ASPs) are needed because 90% of antimicrobials are prescribed in the community. A primary care ASP (PC-ASP) was evaluated for its effectiveness in lowering antibiotic prescriptions for six common infections. Methods: A multi-faceted educational program was assessed using a before-and-after design in four primary care clinics from 2015 through 2017. The primary outcome was the difference between control and intervention clinics in total antibiotic prescriptions for six common infections before and after the intervention. Secondary outcomes included changes in condition-specific antibiotic use, delayed antibiotic prescriptions, prescriptions exceeding 7 days duration, use of recommended antibiotics, and emergency department visits or hospitalizations within 30 days. Multi-method models adjusting for demographics, case mix, and clustering by physician were used to estimate treatment effects. Results: Total antibiotic prescriptions in control and intervention clinics did not differ (difference in differences = 1.7%; 95% CI -12.5% to 15.9%), nor did use of delayed prescriptions (-5.2%; 95% CI -24.2% to 13.8%). Prescriptions for longer than 7 days were significantly reduced (-21.3%; 95% CI -42.5% to -0.1%). However, only 781 of 1,777 encounters (44.0%) involved providers who completed the ASP education. Where providers completed the education, delayed prescriptions increased 17.7% (p = 0.06), and prescriptions exceeding 7 days duration declined (-27%; 95% CI -48.3% to -5.6%). Subsequent emergency department visits and hospitalizations did not increase. Conclusions: PC-ASP effectiveness on antibiotic use was variable. Shorter prescription durations and increased use of delayed prescriptions were adopted by engaged primary care providers.

Historique: Des programmes de gestion antimicrobienne (PGA) communautaires efficaces doivent exister, parce que 90 % des antimicrobiens sont prescrits dans la communauté. Des chercheurs ont évalué un PGA en première ligne (PGA-PL) afin d'en déterminer l'efficacité à réduire les prescriptions d'antibiotiques pour six infections courantes. Méthodologie: Les chercheurs ont évalué un programme de formation polyvalent au moyen d'une méthodologie avant-après dans quatre cliniques de soins de première ligne entre 2015 et 2017. Le résultat clinique primaire était la différence entre les cliniques de contrôle et d'intervention pour ce qui est du total de prescriptions antibiotiques contre six infections courantes avant et après l'intervention. Les résultats cliniques secondaires incluaient des modifications à l'utilisation des antibiotiques propres au trouble de santé, le report des prescriptions d'antibiotiques, des prescriptions de plus de sept jours, l'utilisation des antibiotiques recommandés et les visites à l'urgence ou les hospitalisations dans les 30 jours. Les chercheurs ont utilisé des méthodes multimodèles tenant compte de la démographie, du mélange de cas et du regroupement par médecin pour évaluer l'effet des traitements. Résultats: Les prescriptions totales d'antibiotiques dans les cliniques de contrôle et d'intervention ne différaient pas (différences des différences = 1,7 %; IC à 95 %, ­12,5 % à 15,9 %), ni l'utilisation de prescriptions reportées (­5,2 %; IC à 95 %, ­24,2 % à 13,8 %). Les prescriptions de plus de sept jours étaient très peu courantes (­21,3 %; IC à 95 %, ­42,5 % à ­0,1 %). Cependant, seulement 781 des 1 777 rencontres (44,0 %) avaient eu lieu avec des dispensateurs qui avaient suivi la formation sur le PGA. Lorsque les dispensateurs avaient suivi la formation, les reports de prescriptions augmentaient de 17,7 % (p = 0,06) et les prescriptions de plus de sept jours diminuaient (­27 %; IC à 95 %, ­48,3 % à ­5,6 %). Les visites subséquentes à l'urgence et les hospitalisations n'ont pas augmenté. Conclusions: L'efficacité du PGA-PL pour l'utilisation d'antibiotiques était variable. Les dispensateurs de soins de première ligne qui y avaient participé préparaient des prescriptions de moins longue durée et reportaient davantage leurs prescriptions.

Barriers and facilitators to the uptake of an antimicrobial stewardship program in primary care: A qualitative study.

The overuse of antimicrobials in primary care can be linked to an increased risk of antimicrobial-resistant bacteria for individual patients. Although there are promising signs of the benefits associated with Antimicrobial Stewardship Programs (ASPs) in hospitals and long-term care settings, there is limited knowledge in primary care settings and how to implement ASPs in these settings is unclear. In this context, a qualitative study was undertaken to explore the perceptions of primary care prescribers of the usefulness, feasibility, and experiences associated with the implementation of a pilot community-focused ASP intervention in three primary care clinics. Qualitative interviews were conducted with primary care clinicians, including local ASP champions, prescribers, and other primary health care team members, while they participated in an ASP initiative within one of three primary care clinics. An iterative conventional content analyses approach was used to analyze the transcribed interviews. Themes emerged around the key enablers and barriers associated with ASP implementation. Study findings point to key insights relevant to the scalability of community ASP activities with primary care providers.

Nudging In MicroBiology Laboratory Evaluation (NIMBLE): A scoping review.

BACKGROUND: Nudging in microbiology is an antimicrobial stewardship strategy to influence decision making through the strategic reporting of microbiology results while preserving prescriber autonomy. The purpose of this scoping review was to identify the evidence that demonstrates the effectiveness of nudging strategies in susceptibility result reporting to improve antimicrobial use. METHODS: A search for studies in Ovid MEDLINE, Embase, PsycINFO, and All EBM Reviews was conducted. All simulated and vignette studies were excluded. Two independent reviewers were used throughout screening and data extraction. RESULTS: Of a total of 1,346 citations screened, 15 relevant studies were identified. Study types included pre- and postintervention (n = 10), retrospective cohort (n = 4), and a randomized controlled trial (n = 1). Most studies were performed in acute-care settings (n = 13), and the remainder were in primary care (n = 2). Most studies used a strategy to alter the default antibiotic choices on the antibiotic report. All studies reported at least 1 outcome of antimicrobial use: utilization (n = 9), appropriateness (n = 7), de-escalation (n = 2), and cost (n = 1). Moreover, 12 studies reported an overall benefit in antimicrobial use outcomes associated with nudging, and 4 studies evaluated the association of nudging strategy with subsequent antimicrobial resistance, with 2 studies noting overall improvement. CONCLUSIONS: The number of heterogeneous studies evaluating the impact of applying nudging strategies to susceptibility result reports is small; however, most strategies do show promise in altering prescriber's antibiotic selection. Selective and cascade reporting of targeted agents in a hospital setting represent the majority of current research. Gaps and opportunities for future research identified from our scoping review include performing prospective randomized controlled trials and evaluating other approaches aside from selective reporting.

Long-Term Effects of Phased Implementation of Antimicrobial Stewardship in Academic ICUs: 2007-2015.

OBJECTIVES: Antimicrobial stewardship is advocated to reduce antimicrobial resistance in ICUs by reducing unnecessary antimicrobial consumption. Evidence has been limited to short, single-center studies. We evaluated whether antimicrobial stewardship in ICUs could reduce antimicrobial consumption and costs. DESIGN: We conducted a phased, multisite cohort study of a quality improvement initiative. SETTING: Antimicrobial stewardship was implemented in four academic ICUs in Toronto, Canada beginning in February 2009 and ending in July 2012. PATIENTS: All patients admitted to each ICU from January 1, 2007, to December 31, 2015, were included. INTERVENTIONS: Antimicrobial stewardship was delivered using in-person coaching by pharmacists and physicians three to five times weekly, and supplemented with unit-based performance reports. Total monthly antimicrobial consumption (measured by defined daily doses/100 patient-days) and costs (Canadian dollars/100 patient-days) before and after antimicrobial stewardship implementation were measured. MEASUREMENTS AND MAIN RESULTS: A total of 239,123 patient-days (57,195 patients) were analyzed, with 148,832 patient-days following introduction of antimicrobial stewardship. Antibacterial use decreased from 120.90 to 110.50 defined daily dose/100 patient-days following introduction of antimicrobial stewardship (adjusted intervention effect -12.12 defined daily dose/100 patient-days; 95% CI, -16.75 to -7.49; p < 0.001) and total antifungal use decreased from 30.53 to 27.37 defined daily doses/100 patient-days (adjusted intervention effect -3.16 defined daily dose/100 patient-days; 95% CI, -8.33 to 0.04; p = 0.05). Monthly antimicrobial costs decreased from $3195.56 to $1998.59 (adjusted intervention effect -$642.35; 95% CI, -$905.85 to -$378.84; p < 0.001) and total antifungal costs were unchanged from $1771.86 to $2027.54 (adjusted intervention effect -$355.27; 95% CI, -$837.88 to $127.33; p = 0.15). Mortality remained unchanged, with no consistent effects on antimicrobial resistance and candidemia. CONCLUSIONS: Antimicrobial stewardship in ICUs with coaching plus audit and feedback is associated with sustained improvements in antimicrobial consumption and cost. ICUs with high antimicrobial consumption or expenditure should consider implementing antimicrobial stewardship programs.

Sepsis now a priority: a quality improvement initiative for early sepsis recognition and care.

OBJECTIVE: To develop a triage-based screening algorithm and treatment order-sets aimed at improving the quality of care of all patients with sepsis presenting to our emergency department (ED). DESIGN: Retrospective cohort study conducted during a pre-intervention period from 1 April 2010 to 31 March 2011 and a post-intervention period from 1 September 2014 to 30 April 2015. SETTING: A large teaching hospital located in Toronto, Ontario, Canada with a 35-bed ED. PARTICIPANTS: All patients meeting pre-specified sepsis criteria during the ED encounter. MAIN OUTCOME MEASURES: Process of care measures included time to assessment by emergency physician, lactate measurement, blood culture collection, fluid and antibiotic administration. Intensive care unit (ICU) outcomes including admissions, length of stay (LOS) and deaths were reviewed. RESULTS: There were 346 patients pre-intervention, and 270 patients post-intervention. We significantly improved all process measures including mean time to antibiotics by 60 min (P = 0.003) and proportion of patients receiving fluid resuscitation (64.7% vs. 94.4%, P < 0.001). There was no significant difference in the number of patients admitted to ICU (P = 0.14). The median ICU LOS was shorter in the post-intervention group [2.0 days (interquartile range (IQR) 1.0-4.5 days) vs. 5.0 days (IQR 1.5-10.8 days), P = 0.04], and there was no difference in in-hospital mortality between groups (P = 0.27). CONCLUSIONS: We have demonstrated that a triage-based sepsis screening tool results in expedited and consistent delivery of care, with a significant improvement in initial resuscitation measures.

Development and Assessment of a Physician-Specific Antimicrobial Usage and Spectrum Feedback Tool.

Individualized data are required but difficult to obtain for effective antimicrobial stewardship audit and feedback. We developed a summative tool to evaluate consumption (days of therapy per 100 patient-days) and spectrum of antimicrobials that was also acceptable to individual clinicians.

Evaluation of the reproducibility of the Naranjo Adverse Drug Reaction Probability Scale score in published case reports.

STUDY OBJECTIVE: To assess the reproducibility of Naranjo Adverse Drug Reaction Probability Scale (APS) scores in published case reports. DESIGN: Reliability analysis. MEASUREMENTS AND MAIN RESULTS: Randomly selected case reports using the APS were identified from the Web of Science database. The APS scores were blinded from the case reports, and scores were then independently calculated by four raters, using the APS. The percentage of exact agreement between raters' and the published APS scores was calculated for all case reports. Categorical scores were compared by using a weighted κ statistic. For numerical scores, descriptive statistics were computed by using raw and absolute difference scores. Twenty-four case reports were independently scored by four raters. Exact agreement between all raters' scores and the published APS scores was found in five (21%) of the 24 reports. Agreement between individual rater's scores and the published categorical score ranged from 42% to 79%. Weighted κ ranged from 0.12 to 0.61, corresponding to strengths of agreement between poor and good. Difference in scoring by raters resulted in 18% and 27% of case reports being reclassified into higher and lower than reported APS categories, respectively. CONCLUSION: Exact agreement between raters' scores and the published APS score was infrequent. We recommend that authors of case reports include all pertinent details of the case and that journals ensure the robustness of the causality assessment during peer review.

(234)U/(238)U signatures associated with uranium ore bodies: part 1 Ranger 3.

The Ranger 3 ore body is an early Proterozoic U ore body in the Alligator Rivers U province, Northern Territory, Australia. It has surface expression with a redox front located between 30 and 50 m below the surface. The ground water U concentration and (234)U/(238)U AR signature in the top 10 m of the weathered zone are reported for 357 samples collected over 4 wet seasons, at 5 depths, along a transect in-line with the hydraulic gradient and along the centre line of the ore body and its associated dispersion halo. The results show that the weathered zone displays a general U isotope feature for this type of ore body with the (234)U/(238)U AR for the ground water and amorphous phase of the solid matrix being less than 1. The ground water (234)U/(238)U AR is independent of the annual monsoonal climate and depth within the range surface to 10 m. In the vicinity of the U ore body the ground water (234)U/(238)U AR is 0.75 and is very similar to the (234)U/(238)U AR of the amorphous phase of the solid (0.76). The (234)U/(238)U ARs of the amorphous phase and ground water rise and separate to values of 0.88 and 1.02 at the end of the transect. The rise and separation in (234)U/(238)U AR are interpreted as evidence that the source of the U in the ground water is from the water-soluble sub-phase of the amorphous phase and that the ground water flow is too fast to allow the processes occurring across the solid-water interface to reach chemical equilibrium. The data set is a robust characterisation of the coarse and fine detail of the (234)U/(238)U AR signature in the weathered zone of U ore bodies.

(234)U/(238)U signatures associated with uranium ore bodies: part 2 Manyingee.

The Manyingee ore body is a roll-front U ore body located at depth in the Cretaceous sandstone sediments of a Proterozoic palaeo valley. It is located in a confined aquifer. The aquifer is recharged 4 km upstream by the Ashburton River. Groundwater samples were collected at and up to 4.7 km downstream of the ore body. The ground water (234)U/(238)U activity ratios (AR) were elevated to 1.86 in the vicinity of the ore body and then declined to 1.06 over the 4.7 km transect. The elevated (234)U/(238)U ARs are attributed to selective leaching of (234)U sites by oxidising waters, with α recoil as a necessary precursor to produce activated (234)U sites. Direct ejection into another phase following α recoil is considered to be a minor contributor to (234)U -(238)U disequilibrium in this environment. The profile is considered to be typical of the (234)U/(238)U AR profile at and down gradient of the redox front of a U ore body.