Policy interventions and competing management paradigms shape the long-term distribution of forest harvesting across the landscape.

Industrial economic models of natural resource management often incentivize the sequential harvesting of resources based on profitability, disproportionately targeting the higher-value elements of the environment. In fisheries, this issue is framed as a problem of "fishing down the food chain" when these elements represent different trophic levels or sequential depletion more generally. Harvesting that focuses on high grading the most profitable, productive, and accessible components of environmental gradients is also thought to occur in the forestry sector. Such a paradigm is inconsistent with a stewardship ethic, entrenched in the forestry literature, that seeks to maintain or enhance forest condition over time. We ask 1) how these conflicting paradigms have influenced patterns of forest harvesting over time and 2) whether more recent conservation-oriented policies influenced these historical harvesting patterns. We use detailed harvest data over a 47-y period and aggregated time series data that span over a century on the central coast of British Columbia, Canada to assess temporal changes in how logging is distributed among various classes of site productivity and terrain accessibility, corresponding to timber value. Most of this record shows a distinct trend of harvesting shifting over time to less productive stands, with some evidence of harvesting occurring in increasingly less accessible forests. However, stewardship-oriented policy changes enacted in the mid-1990s appear to have strongly affected these trends. This illustrates both a profit-maximizing tendency to log down the value chain when choices are unconstrained and the potential of policy choices to impose a greater stewardship ethic on harvesting behavior.

Building the future of ID: A call to action for quality improvement research and measurement.

Quality is central to value-based care and measurement is essential for assessing performance and understanding improvement over time. Both value-based care and methods for quality measurement are evolving. Infectious Diseases has been less engaged than other specialties in quality measure development, and Infectious Diseases providers must seize the opportunity to engage with quality measure development and research. Antimicrobial stewardship programs are an ideal starting point for Infectious Diseases-related quality measure development; antimicrobial stewardship program interventions and best practices are Infectious Diseases-specific, measurable, and impactful, yet grossly undercompensated. Herein, we provide a scheme for prioritizing research focused on development of Infectious Diseases-specific quality measures. Maturation of quality measurement research in Infectious Diseases, beginning with an initial focus on stewardship-related conditions then expanding to non-stewardship topics, will allow Infectious Diseases to take control of its future in value-based care, and promote the growth of Infectious Diseases through greater recognition of its value.

Applications of machine learning on electronic health record data to combat antibiotic resistance.

There is growing excitement about the clinical use of artificial intelligence and machine learning technologies. Advancements in computing and the accessibility of machine learning frameworks enable researchers to easily train predictive models using electronic health record data. However, there are several practical factors that must be considered when employing machine learning on electronic health record data. We provide a primer on machine learning and approaches commonly taken to address these challenges. To illustrate how these approaches have been applied to address antimicrobial resistance, we review the use of electronic health record data to construct machine learning models for predicting pathogen carriage or infection, optimizing empiric therapy, and aiding antimicrobial stewardship tasks. Machine learning shows promise in promoting the appropriate use of antimicrobials, although clinical deployment is limited. We conclude by describing potential dangers of, and barriers to, implementation of machine learning models in the clinic.

Review: Diagnostic Potential for Collaborative Pharyngitis Biomarkers.

Pharyngitis is an inflammatory condition of the pharynx and/or tonsils commonly seen in both children and adults. Viruses and bacteria represent the most common encountered etiologic agents-yeast/fungi and parasites are infrequently implicated. Some of these are predominantly observed in unique populations (eg, immunocompromised or unvaccinated individuals). This manuscript (part 3 of 3) summarizes the current state of biomarker diagnostic testing and highlights the expanding role they will likely play in the expedited diagnosis and management of patients with acute pharyngitis. Biomarkers, in conjunction with rapid antigen and/or nucleic acid amplification testing, will likely become the standard of care to accurately diagnose the etiologic agent(s) of pharyngitis. This novel testing paradigm has the potential to guide appropriate patient management and antibiotic stewardship by accurately determining if the cause of pharyngitis is due to a viral or bacterial etiology.

Impact of Metagenomic Next-Generation Sequencing of Bronchoalveolar Lavage Fluid on Antimicrobial Stewardship in Patients With Lower Respiratory Tract Infections: A Retrospective Cohort Study.

BACKGROUND: The impact of metagenomic next-generation sequencing (mNGS) on antimicrobial stewardship in patients with lower respiratory tract infections (LRTIs) is still unknown. METHODS: This retrospective cohort study included patients who had LRTIs diagnosed and underwent bronchoalveolar lavage between September 2019 and December 2020. Patients who underwent both mNGS and conventional microbiologic tests were classified as the mNGS group, while those with conventional tests only were included as a control group. A 1:1 propensity score match for baseline variables was conducted, after which changes in antimicrobial stewardship between the 2 groups were assessed. RESULTS: A total of 681 patients who had an initial diagnosis of LRTIs and underwent bronchoalveolar lavage were evaluated; 306 patients were finally included, with 153 in each group. mNGS was associated with lower rates of antibiotic escalation than in the control group (adjusted odds ratio, 0.466 [95% confidence interval, .237-.919]; P = .02), but there was no association with antibiotic de-escalation. Compared with the control group, more patients discontinued the use of antivirals in the mNGS group. CONCLUSIONS: The use of mNGS was associated with lower rates of antibiotic escalation and may facilitate the cessation of antivirals, but not contribute to antibiotic de-escalation in patients with LRTIs.

Antibiotics on Demand: Advances in Asynchronous Telemedicine Call for Increased Antibiotic Surveillance.

The rapid growth of telehealth services has brought about direct-to-consumer telemedicine platforms, enabling patients to request antibiotics online without a virtual or face-to-face consultation. While telemedicine aims to enhance accessibility, this trend raises significant concerns regarding appropriate antimicrobial use and patient safety. In this viewpoint, we share our first-hand experience with 2 direct-to-consumer platforms, where we intentionally sought inappropriate antibiotic prescriptions for nonspecific symptoms strongly indicative of a viral upper respiratory infection. Despite the lack of clear necessity, requested antibiotic prescriptions were readily transmitted to our local pharmacy following a simple monetary transaction. The effortless acquisition of patient-selected antibiotics online, devoid of personal interactions or consultations, underscores the urgent imperative for intensified antimicrobial stewardship initiatives led by state and national public health organizations in telehealth settings. By augmenting oversight and regulation, we can ensure the responsible and judicious use of antibiotics, safeguard patient well-being, and preserve the efficacy of these vital medications.

Development of an Electronic Clinical Surveillance Measure for Unnecessary Rapid Antibiotic Administration in Suspected Sepsis.

BACKGROUND: Substantial efforts focus on monitoring and reducing delays in antibiotic treatment for sepsis, but little has been done to characterize the balancing measure of sepsis overtreatment. We aimed to establish preliminary validity and usefulness of electronic health record (EHR) data-derived criteria for sepsis overtreatment surveillance (SEP-OS). METHODS: We evaluated adults with potential sepsis (≥2 Systemic Inflammatory Response Syndrome criteria within 6 hours of arrival) presenting to the emergency department of 12 hospitals, excluding patients with shock. We defined SEP-OS as the proportion of patients receiving rapid IV antibiotics (≤3 hours) who did not ultimately meet the Centers for Disease Control Adult Sepsis Event "true sepsis" definition. We evaluated the frequency and characteristics of patients meeting overtreatment criteria and outcomes associated with sepsis overtreatment. RESULTS: Of 113 764 eligible patients, the prevalence of sepsis overtreatment was 22.5%. The measure met prespecified criteria for reliability, content, construct, and criterion validity. Patients classified by the SEP-OS overtreatment criteria had higher median antibiotic days (4 days [IQR, 2-5] vs 1 day [1-2]; P < .01), longer median length of stay (4 days [2-6] vs 3 days [2-5]; P < .01), higher hospital mortality (2.4% vs 2.1%; P = .01), and higher frequency of Clostridium difficile infection within 6 months of hospital discharge (P < .01) compared with "true negative" cases. CONCLUSIONS: We developed a novel, valid EHR metric for clinical surveillance of sepsis overtreatment. Applying this metric to a large cohort of potential sepsis patients revealed a high rate of overtreatment and provides a useful tool to inform sepsis quality-improvement targets.

Individualized Antibiotic Plans as a Quality Improvement Initiative to Reduce Carbapenem Use for Hematopoietic Cell Transplant Patients at a Freestanding Pediatric Hospital.

BACKGROUND: Providers must balance effective empiric therapy against toxicity risks and collateral damage when selecting antibiotic therapy for patients receiving hematopoietic cell transplant (HCT). Antimicrobial stewardship interventions during HCT are often challenging due to concern for undertreating potential infections. METHODS: In an effort to decrease unnecessary carbapenem exposure for patients undergoing HCT at our pediatric center, we implemented individualized antibiotic plans (IAPs) to provide recommendations for preengraftment neutropenia prophylaxis, empiric treatment of febrile neutropenia, and empiric treatment for hemodynamic instability. We compared monthly antibiotic days of therapy (DOT) adjusted per 1000 patient-days for carbapenems, antipseudomonal cephalosporins, and all antibiotics during two 3-year periods immediately before and after the implementation of IAPs to measure the impact of IAP on prescribing behavior. Bloodstream infection (BSIs) and Clostridioides difficile (CD) positivity test rates were also compared between cohorts. Last, providers were surveyed to assess their experience of using IAPs in antibiotic decision making. RESULTS: Overall antibiotic use decreased after the implementation of IAPs (monthly reduction of 19.6 DOT/1000 patient-days; P = .004), with carbapenems showing a continuing decline after IAP implementation. BSI and CD positivity rates were unchanged. More than 90% of providers found IAPs to be either extremely or very valuable for their practice. CONCLUSIONS: Implementation of IAPs in this high-risk HCT population led to reduction in overall antibiotic use without increase in rate of BSI or CD test positivity. The program was well received by providers.

Antibiotic Prescribing Patterns for Respiratory Tract Illnesses Following the Conclusion of an Education and Feedback Intervention in Primary Care.

BACKGROUND: A study previously conducted in primary care practices found that implementation of an educational session and peer comparison feedback was associated with reduced antibiotic prescribing for respiratory tract diagnoses (RTDs). Here, we assess the long-term effects of this intervention on antibiotic prescribing following cessation of feedback. METHODS: RTD encounters were grouped into tiers based on antibiotic prescribing appropriateness: tier 1, almost always indicated; tier 2, possibly indicated; and tier 3, rarely indicated. A χ2 test was used to compare prescribing between 3 time periods: pre-intervention, intervention, and post-intervention (14 months following cessation of feedback). A mixed-effects multivariable logistic regression analysis was performed to assess the association between period and prescribing. RESULTS: We analyzed 260 900 RTD encounters from 29 practices. Antibiotic prescribing was more frequent in the post-intervention period than in the intervention period (28.9% vs 23.0%, P < .001) but remained lower than the 35.2% pre-intervention rate (P < .001). In multivariable analysis, the odds of prescribing were higher in the post-intervention period than the intervention period for tier 2 (odds ratio [OR], 1.19; 95% confidence interval [CI]: 1.10-1.30; P < .05) and tier 3 (OR, 1.20; 95% CI: 1.12-1.30) indications but was lower compared to the pre-intervention period for each tier (OR, 0.66; 95% CI: 0.59-0.73 tier 2; OR, 0.68; 95% CI: 0.61-0.75 tier 3). CONCLUSIONS: The intervention effects appeared to last beyond the intervention period. However, without ongoing provider feedback, there was a trend toward increased prescribing. Future studies are needed to determine optimal strategies to sustain intervention effects.

State-of-the-Art Review: Use of Antimicrobials at the End of Life.

Navigating antibiotics at the end of life is a challenge for infectious disease (ID) physicians who remain deeply committed to providing patient-centered care and engaging in shared decision making. ID physicians, who often see patients in both inpatient and outpatient settings and maintain continuity of care for patients with refractory or recurrent infections, are ideally situated to provide guidance that aligns with patients' goals and values. Complex communication skills, including navigating difficult emotions around end-of-life care, can be used to better direct shared decision making and assist with antibiotic stewardship.

Changes in the Appropriateness of US Outpatient Antibiotic Prescribing After the COVID-19 Outbreak: An Interrupted Time Series Analysis of 2016-2021 Data.

BACKGROUND: No national study has evaluated changes in the appropriateness of US outpatient antibiotic prescribing across all conditions and age groups after the coronavirus disease 2019 (COVID-19) outbreak in March 2020. METHODS: This was an interrupted time series analysis of Optum's de-identified Clinformatics Data Mart Database, a national commercial and Medicare Advantage claims database. Analyses included prescriptions for antibiotics dispensed to children and adults enrolled during each month during 2017-2021. For each prescription, we applied our previously developed antibiotic appropriateness classification scheme to International Classification of Diseases, Tenth Revision, Clinical Modification diagnosis codes on medical claims occurring on or during the 3 days prior to dispensing. Outcomes included the monthly proportion of antibiotic prescriptions that were inappropriate and the monthly proportion of enrollees with ≥1 inappropriate prescription. Using segmented regression models, we assessed for level and slope changes in outcomes in March 2020. RESULTS: Analyses included 37 566 581 enrollees, of whom 19 154 059 (51.0%) were female. The proportion of enrollees with ≥1 inappropriate prescription decreased in March 2020 (level decrease: -0.80 percentage points [95% confidence interval {CI}, -1.09% to -.51%]) and subsequently increased (slope increase: 0.02 percentage points per month [95% CI, .01%-.03%]), partly because overall antibiotic dispensing rebounded and partly because the proportion of antibiotic prescriptions that were inappropriate increased (slope increase: 0.11 percentage points per month [95% CI, .04%-.18%]). In December 2021, the proportion of enrollees with ≥1 inappropriate prescription equaled the corresponding proportion in December 2019. CONCLUSIONS: Despite an initial decline, the proportion of enrollees exposed to inappropriate antibiotics returned to baseline levels by December 2021. Findings underscore the continued importance of outpatient antibiotic stewardship initiatives.

Performance of Urinalysis Parameters in Predicting Urinary Tract Infection: Does One Size Fit All?

In a multihospital cohort study of 3392 patients, positive urinalysis parameters had poor positive predictive value for diagnosing urinary tract infection (UTI). Combined urinalysis parameters (pyuria or nitrite) performed better than pyuria alone for ruling out UTI. However, performance of all urinalysis parameters was poor in older women.

Drivers of Geographic Patterns in Outpatient Antibiotic Prescribing in the United States.

In a retrospective, ecological analysis of US medical claims, visit rates explained more of the geographic variation in outpatient antibiotic prescribing rates than per-visit prescribing. Efforts to reduce antibiotic use may benefit from addressing the factors that drive higher rates of outpatient visits, in addition to continued focus on stewardship.

The Use of Long-term Antibiotics for Suppression of Bacterial Infections.

Suppressive antibiotic therapy is prescribed when a patient has an infection that is presumed to be incurable by a defined course of therapy or source control. The cohort receiving suppressive antibiotic therapy is typically highly comorbid and the infections often involve retained prosthetic material. In part due to a lack of clear guidelines regarding the use of suppressive antibiotics, and in part due to the complex nature of the infections in question, patients are often prescribed suppressive antibiotics for extremely long, if not indefinite, courses. The risks of prolonged antibiotic exposure in this context are not fully characterized, but they include adverse drug effects ranging from mild to severe, the development of antibiotic-resistant organisms, and perturbations of the gastrointestinal microbiome. In this narrative review we present the available evidence for the use of suppressive antibiotic therapy in 4 common indications, examine the gaps in the current literature, and explore the known and potential risks of this therapy. We also make suggestions for improving the quality of evidence in future studies, particularly by highlighting the need for a standardized term to describe the use of long courses of antibiotics to suppress hard-to-treat infections.

The Effect of COVID-19 Vaccination on Outpatient Antibiotic Prescribing in Older Adults: A Self-Controlled Risk-Interval Study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) vaccination has been associated with reduced outpatient antibiotic prescribing among older adults with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We assessed the impact of COVID-19 vaccination on outpatient antibiotic prescribing in the broader population of older adults, regardless of SARS-CoV-2 infection status. METHODS: We included adults aged ≥65 years who received their first, second, and/or third COVID-19 vaccine dose from December 2020 to December 2022. We used a self-controlled risk-interval design and included cases who received an antibiotic prescription 2-6 weeks before vaccination (pre-vaccination or control interval) or after vaccination (post-vaccination or risk interval). We used conditional logistic regression to estimate the odds of being prescribed (1) any antibiotic, (2) a typical "respiratory" infection antibiotic, or (3) a typical "urinary tract" infection antibiotic (negative control) in the post-vaccination interval versus the pre-vaccination interval. We accounted for temporal changes in antibiotic prescribing using background monthly antibiotic prescribing counts. RESULTS: 469 923 vaccine doses met inclusion criteria. The odds of receiving any antibiotic or a respiratory antibiotic prescription were lower in the post-vaccination versus pre-vaccination interval (aOR, .973; 95% CI, .968-.978; aOR, .961; 95% CI, .953-.968, respectively). There was no association between vaccination and urinary antibiotic prescriptions (aOR, .996; 95% CI, .987-1.006). Periods with high (>10%) versus low (<5%) SARS-CoV-2 test positivity demonstrated greater reductions in antibiotic prescribing (aOR, .875; 95% CI, .845-.905; aOR, .996; 95% CI, .989-1.003, respectively). CONCLUSIONS: COVID-19 vaccination was associated with reduced outpatient antibiotic prescribing in older adults, especially during periods of high SARS-CoV-2 circulation.

Impact of the COVID-19 Pandemic on Inpatient Antibiotic Use in the United States, January 2019 Through July 2022.

Antimicrobial use data reported to the National Healthcare Safety Network's Antimicrobial Use and Resistance Module between January 2019 and July 2022 were analyzed to assess the impact of the COVID-19 pandemic on inpatient antimicrobial use.

Raising AWaRe-ness of Antimicrobial Stewardship Challenges in Pediatric Emergency Care: Results from the PERFORM Study Assessing Consistency and Appropriateness of Antibiotic Prescribing Across Europe.

BACKGROUND: Optimization of antimicrobial stewardship is key to tackling antimicrobial resistance, which is exacerbated by overprescription of antibiotics in pediatric emergency departments (EDs). We described patterns of empiric antibiotic use in European EDs and characterized appropriateness and consistency of prescribing. METHODS: Between August 2016 and December 2019, febrile children attending EDs in 9 European countries with suspected infection were recruited into the PERFORM (Personalised Risk Assessment in Febrile Illness to Optimise Real-Life Management) study. Empiric systemic antibiotic use was determined in view of assigned final "bacterial" or "viral" phenotype. Antibiotics were classified according to the World Health Organization (WHO) AWaRe classification. RESULTS: Of 2130 febrile episodes (excluding children with nonbacterial/nonviral phenotypes), 1549 (72.7%) were assigned a bacterial and 581 (27.3%) a viral phenotype. A total of 1318 of 1549 episodes (85.1%) with a bacterial and 269 of 581 (46.3%) with a viral phenotype received empiric systemic antibiotics (in the first 2 days of admission). Of those, the majority (87.8% in the bacterial and 87.0% in the viral group) received parenteral antibiotics. The top 3 antibiotics prescribed were third-generation cephalosporins, penicillins, and penicillin/ß-lactamase inhibitor combinations. Of those treated with empiric systemic antibiotics in the viral group, 216 of 269 (80.3%) received ≥1 antibiotic in the "Watch" category. CONCLUSIONS: Differentiating bacterial from viral etiology in febrile illness on initial ED presentation remains challenging, resulting in a substantial overprescription of antibiotics. A significant proportion of patients with a viral phenotype received systemic antibiotics, predominantly classified as WHO Watch. Rapid and accurate point-of-care tests in the ED differentiating between bacterial and viral etiology could significantly improve antimicrobial stewardship.

Emulating a Target Trial of Shorter Compared to Longer Course of Antibiotic Therapy for Gram-Negative Bacteremia.

BACKGROUND: Despite the availability of antimicrobial therapies, gram-negative bacteremia remains a significant cause of morbidity and mortality on a global level. Recent randomized controlled trials support shorter antibiotic treatment duration for individuals with uncomplicated gram-negative bacteremia. The target trial framework using the cloning approach utilizes real-world data but eliminates the issue of immortal time bias seen in observational studies by emulating the analysis of randomized trials with full adherence. METHOD: A hypothetical target trial allocating individuals with gram-negative bacteremia to either short antibiotic treatment duration (5-7 days) or longer antibiotic treatment duration (8-14 days) was specified and emulated using the cloning, censoring, and weighting approach. The primary outcome was 90-day all-cause mortality. Secondary outcome was a composite endpoint of clinical and microbiological relapse. The emulated trial included individuals from four hospitals in Copenhagen from 2018 through 2021. RESULTS: In sum, 1040 individuals were included. The median age of the cohort was 76 years, the majority were male (54%), had community-acquired gram-negative bacteremia (86%), urinary tract infection as the source of the infection (78%), and Escherichia coli as the pathogen of the infection (73%). The adjusted 90-day risk difference in all-cause mortality was 1.3% (95% confidence interval [CI]: -.7, 3.3), and the risk ratio was 1.12 (95% CI: .89, 1.37). The adjusted 90-day risk difference in relapse was 0.7% (95% CI: -2.3, 3.8), and the risk ratio was 1.07 (95% CI: .71, 1.45). CONCLUSIONS: We found comparative outcomes for shorter treatment duration compared to longer treatment duration in patients with gram-negative bacteremia.

A Novel Risk-Adjusted Metric to Compare Hospitals on Their Antibiotic Prescribing at Hospital Discharge.

BACKGROUND: Antibiotic overuse at hospital discharge is common, but there is no metric to evaluate hospital performance at this transition of care. We built a risk-adjusted metric for comparing hospitals on their overall post-discharge antibiotic use. METHODS: This was a retrospective study across all acute-care admissions within the Veterans Health Administration during 2018-2021. For patients discharged to home, we collected data on antibiotics and relevant covariates. We built a zero-inflated, negative, binomial mixed model with 2 random intercepts for each hospital to predict post-discharge antibiotic exposure and length of therapy (LOT). Data were split into training and testing sets to evaluate model performance using absolute error. Hospital performance was determined by the predicted random intercepts. RESULTS: 1 804 300 patient-admissions across 129 hospitals were included. Antibiotics were prescribed to 41.5% while hospitalized and 19.5% at discharge. Median LOT among those prescribed post-discharge antibiotics was 7 (IQR, 4-10) days. The predictive model detected post-discharge antibiotic use with fidelity, including accurate identification of any exposure (area under the precision-recall curve = 0.97) and reliable prediction of post-discharge LOT (mean absolute error = 1.48). Based on this model, 39 (30.2%) hospitals prescribed antibiotics less often than expected at discharge and used shorter LOT than expected. Twenty-eight (21.7%) hospitals prescribed antibiotics more often at discharge and used longer LOT. CONCLUSIONS: A model using electronically available data was able to predict antibiotic use prescribed at hospital discharge and showed that some hospitals were more successful in reducing antibiotic overuse at this transition of care. This metric may help hospitals identify opportunities for improved antibiotic stewardship at discharge.

Comparative safety of different antibiotic regimens for the treatment of outpatient community-acquired pneumonia among otherwise healthy adults.

BACKGROUND: Evidence is limited about the comparative safety of antibiotic regimens for treatment of community-acquired pneumonia (CAP). We compared the risk of adverse drug events (ADEs) associated with antibiotic regimens for CAP treatment among otherwise healthy, non-elderly adults. METHODS: We conducted an active comparator new-user cohort study (2007-2019) of commercially-insured adults 18-64 years diagnosed with outpatient CAP, evaluated via chest x-ray, and dispensed a same-day CAP-related oral antibiotic regimen. ADE follow-up duration ranged from 2-90 days (e.g., renal failure [14 days]). We estimated risk differences [RD] per 100 treatment episodes and risk ratios using propensity score weighted Kaplan-Meier functions. Ankle/knee sprain and influenza vaccination were considered as negative control outcomes. RESULTS: Of 145,137 otherwise healthy CAP patients without comorbidities, 52% received narrow-spectrum regimens (44% macrolide, 8% doxycycline) and 48% received broad-spectrum regimens (39% fluoroquinolone, 7% ß-lactam, 3% ß-lactam + macrolide). Compared to macrolide monotherapy, each broad-spectrum antibiotic regimen was associated with increased risk of several ADEs (e.g., ß-lactam: nausea/vomiting/abdominal pain [RD per 100, 0.32; 95% CI, 0.10-0.57]; non-Clostridioides difficile diarrhea [RD per 100, 0.46; 95% CI, 0.25-0.68]; vulvovaginal candidiasis/vaginitis [RD per 100, 0.36; 95% CI, 0.09-0.69]). Narrow-spectrum antibiotic regimens largely conferred similar risk of ADEs. We generally observed similar risks of each negative control outcome, indicating minimal confounding. CONCLUSIONS: Broad-spectrum antibiotics were associated with increased risk of ADEs among otherwise healthy adults treated for CAP in the outpatient setting. Antimicrobial stewardship is needed to promote judicious use of broad-spectrum antibiotics and ultimately decrease antibiotic-related ADEs.