"What if the patient has a severe reaction, and it is my fault?" A qualitative study exploring factors for sustainable implementation of penicillin allergy delabelling.

BACKGROUND: Penicillin allergy delabelling (PAD), the process of evaluating penicillin allergy labels, is a key target in antibiotic stewardship, but uptake of the procedure outside clinical studies is limited. We aimed to explore factors that need to be addressed to sustainably implement a clinical pathway for PAD. METHODS: We conducted a qualitative study based on semi-structured interviews with focus groups consisting of a purposive sample of twenty-five nurses and physicians working in four different hospitals in Western Norway. Systematic text condensation was applied for analysis. RESULTS: Psychological safety was reported as crucial for clinicians to perform PAD. A narrative of uncertainty and anticipated negative outcomes were negatively associated with PAD performance. Education, guidelines, and colleague- and leadership support could together create psychological safety and empower health personnel to perform PAD. Key factors for sustainable implementation of PAD were facilitating the informant's profound motivation for providing optimal health care and for reducing antimicrobial resistance. Informants were motivated by the prospect of a simplified PAD procedure. We identified three main needs for implementation of PAD: (1) creating psychological safety; (2) utilising clinicians' inherent motivation and (3) optimal organisational structures. CONCLUSION: A planned implementation of PAD must acknowledge clinicians' need for psychological safety and aid reassurance through training, leadership, and guidelines. To implement PAD as an everyday practice it must be minimally disruptive and provide a contextually adaptive logistic chain. Also, the clinician's motivation for providing the best possible healthcare should be utilised to aid implementation. The results of this study will aid sustainable implementation of PAD in Norway. ETHICS: The study was approved by the Western Norway Regional Committee for Medical Research Ethics (Study No:199210).

Knowledge of antimicrobial stewardship and the Access, Watch and Reserve (AWaRe) classification of antibiotics among frontline healthcare professionals in Akwa Ibom State, Nigeria: a cross-sectional study.

BACKGROUND: Antimicrobial stewardship (AMS) aims to improve antibiotic use while reducing resistance and its consequences. There is a paucity of data on the availability of AMS programmes in southern Nigeria. Further, there is no data on Nigerian healthcare professionals' knowledge of the WHO 'Access, Watch and Reserve' (AWaRe) classification of antibiotics. This study sought to assess knowledge of AMS and the AWaRe classification of antibiotics among frontline healthcare professionals in Akwa Ibom State, Nigeria. METHODS: This was a cross-sectional survey of 417 healthcare professionals, comprising medical doctors, pharmacists and nurses, across 17 public hospitals in Akwa Ibom State, Nigeria. A paper-based self-completion questionnaire was used to collect data from the participants during working hours between September and November 2023. Statistical analysis was done using SPSS version 25.0, with p < 0.05 indicating statistical significance. RESULTS: Four hundred and seventeen out of the 500 healthcare professionals approached agreed to participate, giving an 83.4% response rate. Most of the participants were female (62.1%) and nurses (46.3%). Approximately 57% of participants were familiar with the term antibiotic/antimicrobial stewardship, however, only 46.5% selected the correct description of AMS. Majority (53.0%) did not know if AMS programme was available in their hospitals. 79% of participants did not know about AWaRe classification of antibiotics. Among the 87 (20.9%) who knew, 28.7% correctly identified antibiotics into the AWaRe groups from a given list. Only profession significantly predicted knowledge of AMS and awareness of the AWaRe classification of antibiotics (p < 0.001). Pharmacists were more likely to define AMS correctly than medical doctors (odds ratio [OR] = 2.02, 95% confidence interval [CI] = 1.16-3.52, p = 0.012), whereas nurses were less likely to be aware of the WHO AWaRe classification of antibiotics than medical doctors (OR = 0.36, 95% CI = 0.18-0.72, p = 0.004). CONCLUSIONS: There was a notable knowledge deficit in both AMS and the AWaRe classification of antibiotics among participants in this study. This highlights the need for educational interventions targeted at the different cadres of healthcare professionals on the role of AMS programmes in reducing antimicrobial resistance and its consequences.

Surveillance of antimicrobial utilization in Africa: a systematic review and meta-analysis of prescription rates, indications, and quality of use from point prevalence surveys.

BACKGROUND: Antimicrobial resistance (AMR) is a global public health concern that is fueled by the overuse of antimicrobial agents. Low- and middle-income countries, including those in Africa,. Point prevalence surveys (PPS) have been recognized as valuable tools for assessing antimicrobial utilization and guiding quality improvement initiatives. This systematic review and meta-analysis aimed to evaluate the prescription rates, indications, and quality of antimicrobial use in African health facilities. METHODS: A comprehensive search was conducted in multiple databases, including PubMed, Scopus, Embase, Hinari (Research4Life) and Google Scholar. Studies reporting the point prevalence of antimicrobial prescription or use in healthcare settings using validated PPS tools were included. The quality of the studies was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. A random-effects meta-analysis was conducted to combine the estimates. Heterogeneity was evaluated using Q statistics, I² statistics, meta-regression, and sensitivity analysis. Publication bias was assessed using a funnel plot and Egger's regression test, with a p-value of < 0.05 indicating the presence of bias. RESULTS: Out of 1790 potential studies identified, 32 articles were included in the meta-analysis. The pooled prescription rate in acute care hospitals was 60%, with significant heterogeneity (I2 = 99%, p < 0.001). Therapeutic prescriptions constituted 62% of all the prescribed antimicrobials. Prescription quality varied: documentation of reasons in notes was 64%, targeted therapy was 10%, and parenteral prescriptions were 65%, with guideline compliance at 48%. Hospital-acquired infections comprised 20% of all prescriptions. Subgroup analyses revealed regional disparities in antimicrobial prescription prevalence, with Western Africa showing a prevalence of 65% and 44% in Southern Africa. Publication bias adjustment estimated the prescription rate at 54.8%, with sensitivity analysis confirming minor variances among studies. CONCLUSION: This systematic review and meta-analysis provide valuable insights into antimicrobial utilization in African health facilities. The findings highlight the need for improved antimicrobial stewardship and infection control programs to address the high prevalence of irrational antimicrobial prescribing. The study emphasizes the importance of conducting regular surveillance through PPS to gather reliable data on antimicrobial usage, inform policy development, and monitor the effectiveness of interventions aimed at mitigating AMR.

Hospitalised patients as stewards of their own antibiotic therapy: a qualitative analysis informing the strategic design of interventions to encourage shared decision-making in tertiary hospital settings in Singapore.

Background: Shared decision-making (SDM) on antibiotic therapy may improve antibiotic use in tertiary hospitals, but hospitalised patients are apprehensive about being involved in it. Understanding the facilitators and barriers to SDM can inform the design and implementation of interventions to empower these patients to engage in SDM on their antibiotic therapies. Methods: We conducted qualitative interviews with 23 adult patients purposively sampled with maximum variation from the three largest tertiary-care hospitals in Singapore (April 2019─October 2020). Thematic analysis was conducted using the Theoretical Domains Framework and Capability, Opportunity, Motivation, Behaviour (COM-B) model to identify areas for intervention. Results: Hospitalised patients lacked comprehensive knowledge of their antibiotic therapies and the majority did not have the skills to actively query their doctors about them. There was a lack of opportunities to meet and interact with doctors, and patients were less motivated to engage in SDM if they had a self-perceived paternalistic relationship with doctors, trusted their doctors to provide the best treatment, and had self-perceived poor knowledge to engage in SDM. To empower these patients, they should first be educated with antibiotic knowledge. Highlighting potential side effects of antibiotics could motivate them to ask questions about their antibiotic therapies. Environment restructuring, as facilitated by nurses and visual cues to nudge conversations, could create opportunities for interactions and motivating patients into SDM on their antibiotic therapies. Conclusion: Education and environmental restructuring should be explored to empower hospitalised patients to engage in SDM on their antibiotic therapies.

Antibiotic consumption in hospitals in humanitarian settings in Afghanistan, Bangladesh, Democratic Republic of Congo, Ethiopia and South Sudan.

BACKGROUND: Antimicrobial resistance is of great global public health concern. In order to address the paucity of antibiotic consumption data and antimicrobial resistance surveillance systems in hospitals in humanitarian settings, we estimated antibiotic consumption in six hospitals with the aim of developing recommendations for improvements in antimicrobial stewardship programs. METHODS: Six hospitals supported by Médecins sans Frontières were included in the study: Boost-Afghanistan, Kutupalong-Bangladesh, Baraka and Mweso-Democratic Republic of Congo, Kule-Ethiopia, and Bentiu-South Sudan. Data for 36,984 inpatients and antibiotic consumption data were collected from 2018 to 2020. Antibiotics were categorized per World Health Organization Access Watch Reserve classification. Total antibiotic consumption was measured by Defined Daily Doses (DDDs)/1000 bed-days. RESULTS: Average antibiotic consumption in all hospitals was 2745 DDDs/1000 bed-days. Boost hospital had the highest antibiotic consumption (4157 DDDs/1000 bed-days) and Bentiu the lowest (1598 DDDs/1000 bed-days). In all hospitals, Access antibiotics were mostly used (69.7%), followed by Watch antibiotics (30.1%). The most consumed antibiotics were amoxicillin (23.5%), amoxicillin and clavulanic acid (14%), and metronidazole (13.2%). Across all projects, mean annual antibiotic consumption reduced by 22.3% during the study period, mainly driven by the reduction in Boost hospital in Afghanistan. CONCLUSIONS: This was the first study to assess antibiotic consumption by DDD metric in hospitals in humanitarian settings. Antibiotic consumption in project hospitals was higher than those reported from non-humanitarian settings. Routine systematic antibiotic consumption monitoring systems should be implemented in hospitals, accompanied by prescribing audits and point-prevalence surveys, to inform about the volume and appropriateness of antibiotic use and to support antimicrobial stewardship efforts in humanitarian settings.

Quality improvement initiative to reduce URI-associated antibiotic prescriptions among adult primary care providers.

IMPORTANCE: Despite evidence that most upper respiratory infections (URIs) are due to viruses, antibiotics are frequently prescribed for this indication in the outpatient setting. Antibiotic stewardship strategies are needed to reduce adverse patient outcomes and staggering healthcare costs due to resistant infections that ensue from inappropriate prescriptions. OBJECTIVE: To determine if individual provider scorecards detailing antibiotic prescribing rates paired with educational resources reduce inappropriate antibiotic use for URIs in the outpatient primary care setting. DESIGN, SETTING AND PARTICIPANTS: This quality improvement project investigated the number of URI-coded office visits in the primary care setting over three consecutive influenza seasons, which resulted in an antibiotic prescription in Cooper University Healthcare's 14 primary care offices. We compared provider's individual prescribing patterns to their peers' average and created a scorecard that was shared with each provider over a series of intervention phases. Data were collected from a preintervention period (November 2017-February 2018), and two postintervention phases, phase I (November 2018-February 2019) and phase II (November 2019-February 2020). INTERVENTION: A personalised, digital scorecard containing antibiotic-prescribing data for URI-coded visits from the prior influenza season was emailed to each primary care provider. Prior to the subsequent influenza season, prescribers received their updated prescribing rates as well as peer-to-peer comparisons. In both phases, the scorecard was attached to an email with antimicrobial stewardship educational materials. MAIN OUTCOMES AND MEASURES: The primary outcome was a reduction in the number of inappropriate antibiotic prescriptions for URI-related diagnoses. The diagnoses were organised into five broad coding categories, including bronchitis, sinusitis, sore throat excluding strep, influenza and tonsillitis excluding strep.

In adult inpatients with pneumonia, CPOE-based vs. routine stewardship reduced extended-spectrum antibiotic use.

SOURCE CITATION: Gohil SK, Septimus E, Kleinman K, et al. Stewardship prompts to improve antibiotic selection for pneumonia: the INSPIRE randomized clinical trial. JAMA. 2024;331:2007-2017. 38639729.

In adult inpatients with a UTI, CPOE-based vs. routine stewardship reduced extended-spectrum antibiotic use.

SOURCE CITATION: Gohil SK, Septimus E, Kleinman K, et al. Stewardship prompts to improve antibiotic selection for urinary tract infection: the INSPIRE randomized clinical trial. JAMA. 2024;331:2018-2028. 38639723.

Biomarker guided antibiotic stewardship in community acquired pneumonia: A randomized controlled trial.

BACKGROUND: In community-acquired pneumonia (CAP), the role of biomarkers to shorten duration of antibiotic treatment has not been firmly established. We assessed the effectiveness of active feedback of treatment algorithms based on procalcitonin (PCT) and C-reactive protein (CRP), compared to standard care, on the duration of antibiotic treatment in patients hospitalized with community-acquired pneumonia (CAP) in non-ICU wards. METHODS AND FINDINGS: We performed a randomised, open label, parallel group, multi-centre trial in 3 Dutch teaching hospitals. Treatment was guided by a PCT algorithm, CRP algorithm or standard care. Participants were recruited by a member of the study team and randomised at day 2-3 of admission in a 1:1:1 ratio. Treatment was discontinued upon predefined thresholds of biomarkers that were assessed on admission, day 4 and days 5-7 if indicated. The primary outcome was total days on antibiotic treatment until day 30. In total 468 participants were included in this study. The median days on antibiotics (IQR) was 7 (IQR 7-10) in the control group, 4 (IQR 3-7) in the CRP group (rate ratio (RR) of 0.70, 95% CI 0.61-0.82 compared to standard care; p <0.001), and 5.5 (IQR 3-9) in the PCT group (RR of 0.78, 95% CI 0.68-0.89 compared to standard care; p <0.001). New antibiotics within the first 30 days were prescribed to 24, 23 and 35 patients in standard care, CRP and PCT groups, respectively. The hazard ratio for a new prescription in patients in the PCT group compared to standard care 1.63 (CI 0.97-2.75; p = 0.06). No difference in time to clinical stability or length of stay was found. CONCLUSIONS: A strategy of feedback of CRP-guided and PCT-guided treatment algorithms reduced the number of days on antibiotic in the first 30 days after hospital admission in non-ICU wards for CAP. The study was not powered to determine safety of shortening duration of antibiotic treatment. (NCT01964495).

Information Platform for Antibiotics.

Antibiotic stewardship is continuously evolving to incorporate results from novel research, clinical findings, and specialist recommendations. Numerous dedicated information sources, including web-based solutions, are available to keep medical practitioners informed. However, the provided information is often extensive, requiring users to extract the relevant facts. This study aimed to deliver an information platform that provides references, links, and information in a straightforward and engaging manner. Implementing a high-fidelity prototype prioritized medical and patient-oriented functionalities, structured around questions and quizzes. Additionally, the platform offers access to professional references, such as official healthcare guidelines and scientific articles. The development process adhered to design principles and included user testing with established usability measures (SUS, Nielsen's heuristics), resulting in satisfactory scores from IT experts and somewhat lower scores from users. Although designed to cater to a broader range of users, more work is needed to improve usability for the general public.

Community use of oral antibiotics transiently reprofiles the intestinal microbiome in young Bangladeshi children.

Antibiotics may alter the gut microbiome, and this is one of the mechanisms by which antimicrobial resistance may be promoted. Suboptimal antimicrobial stewardship in Asia has been linked to antimicrobial resistance. We aim to examine the relationship between oral antibiotic use and composition and antimicrobial resistance in the gut microbiome in 1093 Bangladeshi infants. We leverage a trial of 8-month-old infants in rural Bangladesh: 61% of children were cumulatively exposed to antibiotics (most commonly cephalosporins and macrolides) over the 12-month study period, including 47% in the first 3 months of the study, usually for fever or respiratory infection. 16S rRNA amplicon sequencing in 11-month-old infants reveals that alpha diversity of the intestinal microbiome is reduced in children who received antibiotics within the previous 7 days; these samples also exhibit enrichment for Enterococcus and Escherichia/Shigella genera. No effect is seen in children who received antibiotics earlier. Using shotgun metagenomics, overall abundance of antimicrobial resistance genes declines over time. Enrichment for an Enterococcus-related antimicrobial resistance gene is observed in children receiving antibiotics within the previous 7 days, but not earlier. Presence of antimicrobial resistance genes is correlated to microbiome composition. In Bangladeshi children, community use of antibiotics transiently reprofiles the gut microbiome.

Coverage of policies to improve antimicrobial stewardship in human medicine in low and middle income countries: results from the Global Survey of Experts on Antimicrobial Resistance.

BACKGROUND: Antimicrobial resistance (AMR) constitutes a major threat to global health. While antimicrobial misuse or overuse is one of the main drivers for AMR, little is known about the extent to which antibiotic misuse is due to a lack of national government-led efforts to enforce rational use in low and middle-income countries (LMICs). METHODS: To assess antimicrobial stewardship and national implementation measures currently in place for optimizing antimicrobial use and for slowing the spread of AMR, we invited public health experts from 138 LMICs to participate in a Global Survey of Experts on Antimicrobial Resistance (GSEAR). Key coverage measures, as reported by experts, were compared across countries and also juxtaposed with estimates collected in the 2020-21 World Health Organization-organized Tripartite AMR Country Self-Assessment Survey (TrACSS). RESULTS: A total of 352 completed surveys from 118 LMICs were analysed. Experts in 67% of the surveyed countries reported a national action plan (NAP) on AMR, 64% reported legislative policies on antimicrobial use, 58% reported national training programs for health professionals, and 10% reported national monitoring systems for antimicrobials. 51% of LMICs had specific targeted policies to limit the sale and use of protected or reserve antibiotics. While 72% of LMICs had prescription requirements for accessing antibiotics, getting antibiotics without a prescription was reported to be possible in practice in 74% of LMICs. On average, country efforts reported in TrACSS were substantially higher than those seen in GSEAR. CONCLUSIONS: In many LMICs, despite the existence of policies aimed at slowing down the spread of AMR, there are still significant gaps in their implementation and enforcement. Increased national efforts in the areas of enforcement and monitoring of antibiotic use as well as regular monitoring of national efforts are urgently needed to reduce inappropriate antibiotic use in LMICs and to slow the spread of AMR globally.

Antimicrobial Stewardship of Oral Third-Generation Cephalosporins in Community Pharmacy: A Single-Center Quasi-Experimental Study.

Proper use of antimicrobials in hospital and outpatient settings is critical for minimizing the occurrence of antimicrobial resistance. Some hospitals have intervened in the inappropriate use of third-generation oral cephalosporins. However, there have been no such studies in community pharmacy settings. This study aimed to investigate how the use of oral third-generation cephalosporins in community pharmacies affects the amount of antimicrobials used. Patients who visited Nakanomaru Pharmacy after being prescribed antimicrobials at target medical institutions between February 2021 and January 2023 were identified. The number of oral antimicrobials used, duration of use, number of prescriptions, patient age and sex, and infectious diseases in the target patients before and after the intervention for the proper use of oral third-generation cephalosporins were retrospectively investigated based on the patients' medication history and prescription receipts. Through efforts to ensure the proper use of oral third-generation cephalosporins, the amount of oral third-generation cephalosporins used has decreased, and the use of penicillins and oral first-generation cephalosporins has increased. There was no increase in the antimicrobial change or relapse rates associated with treatment failure before and after the initiation of appropriate antimicrobial use. By working toward the proper use of oral third-generation cephalosporins in community pharmacies, we were able to reduce the doses of oral third-generation cephalosporins without compromising their therapeutic efficacy. We believe that recommending the selection of narrow-spectrum antimicrobials based on these guidelines will contribute to their proper use.

Multiple impacts of the COVID-19 pandemic and antimicrobial stewardship on antimicrobial resistance in nosocomial infections: an interrupted time series analysis.

Objectives: The emergency response to the COVID-19 pandemic may disrupt hospital management activities of antimicrobial resistance (AMR). This study aimed to determine the changing AMR trend over the period in China when stringent COVID-19 response measures were implemented. Methods: This retrospective study was conducted in a designated hospital for COVID-19 patients in Guangzhou, China from April 2018 to September 2021. The prevalence of 13 antimicrobial-resistant bacteria was compared before and after the COVID-19 responses through Chi-square tests. Interrupted time series (ITS) models on the weekly prevalence of AMR were established to determine the changing trend. Controlled ITS models were performed to compare the differences between subgroups. Results: A total of 10,134 isolates over 1,265 days were collected. And antimicrobial-resistant strains presented in 38.6% of the testing isolates. The weekly AMR prevalence decreased by 0.29 percentage point (95% CI [0.05-0.80]) after antimicrobial stewardship (AMS) policy, despite an increase in the prevalence of penicillin-resistant Streptococcus pneumoniae (from 0/43 to 15/43, p < 0.001), carbapenem-resistant Escherichia coli (from 20/1254 to 41/1184, p = 0.005), and carbapenem-resistant Klebsiella pneumoniae (from 93/889 to 114/828, p = 0.042). And the changing trend did not vary by gender (male vs. female), age (<65 vs. ≥65 years), service setting (outpatient vs. inpatient), care unit (ICU vs. non-ICU), the primary site of infection (Lung vs. others), and Gram type of bacteria (positive vs. negative). Conclusion: The response to COVID-19 did not lead to an increase in overall AMR; however, it appears that management strategy on the prudent use of antimicrobials likely contributed to a sizable long-term drop. The frequency of several multidrug-resistant bacteria continues to increase after the COVID-19 epidemic. It is crucial to continue to monitor AMR when COVID-19 cases have surged in China after the relaxation of restriction measures.

Antibiotic Use in the Surgical Intensive Care Unit.

Judicious use of antibiotics in the critically ill starts with the evaluation for suspected infection, including close consideration of the patient's history. If infection is present or strongly suspected, empiric antibiotics should be promptly initiated and selected based on the source of infection, patient factors, and local resistance patterns. If the surgeon decides source control is indicated, they must determine the optimal approach and timing. As soon as culture and sensitivity data are available, de-escalation to narrower spectrum agents is essential to decrease the risks of antibiotic toxicity and resistance. Importantly, surgeons should participate in antibiotic stewardship in their patients.

Nurturing Tomorrow's Antibiotic Stewards: An Innovative School Campaign to Combat Antimicrobial Resistance in Delhi.

SUMMARY: Antimicrobials are lifesaving medicines, but their misuse drives antimicrobial resistance. Schools, as educational hubs wield transformative potential in fostering responsible antimicrobial behavior among students and the broader community. An online campaign targeted Delhi schools, training teachers as master trainers who, in turn, educated 359,940 students. Significant pre- to post-test score improvements were observed among teachers (6.98-8.14; P < 0.01) and students (5.20-6.56; P < 0.01). The campaign received excellent feedback (85%), with 966 students participating in the "IDEAthon" competition. While a single session improved knowledge, continuous engagement and activities are imperative for sustained behavioral change in antibiotic usage.

Effectiveness of pharmacist-led antimicrobial stewardship programs in perioperative settings: A systematic review and meta-analysis.

OBJECTIVE: We sought to characterize and evaluate the effectiveness of pharmacist-led AMS interventions in improving antimicrobial use and subsequent surgical site infections (SSI) in perioperative settings. METHODS: A systematic review and meta-analysis was conducted by searching PubMed, Embase and CINAHL. Two independent reviewers extracted the data using the Descriptive Elements of Pharmacist Intervention Characterization Tool and undertook quality assessment using the Crowe Critical Appraisal. A meta-analysis was conducted using a random-effect model. RESULTS: Eleven studies were included in this review. Pharmacists were found to have various roles in AMS, including educational sessions, ward rounds, audits and feedback, and guidelines development. The discussion of interventions lacked details on the development. A meta-analysis revealed that pharmacist-led AMS programs in perioperative settings was associated with a significant improvement in antibiotic selection (OR 4.29; 95 % CI 2.52-7.30), administration time (OR 4.93; 95 % CI 2.05-11.84), duration (OR 5.27; 95 % CI 1.58-17.55), and SSI (OR 0.51; 95 % CI 0.34-0.77). CONCLUSION: Pharmacist-led AMS programs were effective in improving antimicrobial prescribing while reducing SSI; however most studies were of moderate quality. Studies lacked the utilization of theory to develop interventions, therefore, it is not clear whether theory-derived interventions are more effective than those without a theoretical element. High-quality, multicomponent, theory-derived, interventional studies using appropriate methodology and standardized data collection, are needed.

Importance of underlying mechanisms for interpreting relative risk of Clostridioides difficile infection among antibiotic-exposed patients in healthcare facilities.

Clostridioides difficile infection (CDI) is a significant public health threat, associated with antibiotic-induced disruption of the normally protective gastrointestinal microbiota. CDI is thought to occur in two stages: acquisition of asymptomatic colonization from ingesting C. difficile bacteria followed by progression to symptomatic CDI caused by toxins produced during C. difficile overgrowth. The degree to which disruptive antibiotic exposure increases susceptibility at each stage is uncertain, which might contribute to divergent published projections of the impact of hospital antibiotic stewardship interventions on CDI. Here, we model C. difficile transmission and CDI among hospital inpatients, including exposure to high-CDI-risk antibiotics and their effects on each stage of CDI epidemiology. We derive the mathematical relationship, using a deterministic model, between those parameters and observed equilibrium levels of colonization, CDI, and risk ratio of CDI among certain antibiotic-exposed patients relative to patients with no recent antibiotic exposure. We then quantify the sensitivity of projected antibiotic stewardship intervention impacts to alternate assumptions. We find that two key parameters, the antibiotic effects on susceptibility to colonization and to CDI progression, are not identifiable given the data frequently available. Furthermore, the effects of antibiotic stewardship interventions are sensitive to their assumed values. Thus, discrepancies between different projections of antibiotic stewardship interventions may be largely due to model assumptions. Data supporting improved quantification of mechanistic antibiotic effects on CDI epidemiology are needed to understand stewardship effects better.