An Open-Label, Randomized Trial Comparing Fidaxomicin With Oral Vancomycin for the Treatment of Clostridioides difficile Infection in Hospitalized Patients Receiving Concomitant Antibiotics for Concurrent Infections.

BACKGROUND: Recurrent Clostridioides difficile infection (rCDI) occurs frequently, and concomitant antibiotic (CA) during the initial episode for treatment of non-CDI is a major risk factor. We sought to address the comparative efficacy of fidaxomicin versus vancomycin in the setting of CA during the initial CDI episode. METHODS: We conducted a randomized, controlled, open-label trial at 2 hospitals in Ann Arbor, Michigan. We consecutively consented and enrolled hospitalized patients ≥18 years old with diarrhea, a positive test for C. difficile, and ≥1 qualifying CA. Complicated CDI, CDI treatment for >24 hours prior to enrollment, and planned long-term (>12 weeks) CA use were notable exclusions. Clinical cure was defined as resolution of diarrhea for 2 consecutive days maintained until 2 days after therapy, and rCDI as recurrent diarrhea with positive testing ≤30 days after initial treatment. Patients were randomized to fidaxomicin or vancomycin. RESULTS: Baseline characteristics were similar in the 2 groups of 144 patients. Rates of clinical cure (73% vs 62.9%, P = .195) and rCDI (3.3% vs 4.0%; P > .99) were similar for fidaxomicin and vancomycin in the intention-to-treat and per-protocol cohorts, respectively. Only 4 patients developed rCDI. CONCLUSIONS: In this study of patients with CDI receiving CA, a numerically higher proportion were cured with fidaxomicin versus vancomycin, but this result did not reach statistical significance. Overall recurrence was lower than anticipated in both arms compared with previous studies that did not extend duration of CDI treatment during CA. CLINICAL TRIALS REGISTRATION: www.clinicaltrials.gov (NCT02692651).

Development of Patient Safety Measures to Identify Inappropriate Diagnosis of Common Infections.

BACKGROUND: Inappropriate diagnosis of infections results in antibiotic overuse and may delay diagnosis of underlying conditions. Here we describe the development and characteristics of 2 safety measures of inappropriate diagnosis of urinary tract infection (UTI) and community-acquired pneumonia (CAP), the most common inpatient infections on general medicine services. METHODS: Measures were developed from guidelines and literature and adapted based on data from patients hospitalized with UTI and CAP in 49 Michigan hospitals and feedback from end-users, a technical expert panel (TEP), and a patient focus group. Each measure was assessed for reliability, validity, feasibility, and usability. RESULTS: Two measures, now endorsed by the National Quality Forum (NQF), were developed. Measure reliability (derived from 24 483 patients) was excellent (0.90 for UTI; 0.91 for CAP). Both measures had strong validity demonstrated through (a) face validity by hospital users, the TEPs, and patient focus group, (b) implicit case review (ĸ 0.72 for UTI; ĸ 0.72 for CAP), and (c) rare case misclassification (4% for UTI; 0% for CAP) due to data errors (<2% for UTI; 6.3% for CAP). Measure implementation through hospital peer comparison in Michigan hospitals (2017 to 2020) demonstrated significant decreases in inappropriate diagnosis of UTI and CAP (37% and 32%, respectively, P < .001), supporting usability. CONCLUSIONS: We developed highly reliable, valid, and usable measures of inappropriate diagnosis of UTI and CAP for hospitalized patients. Hospitals seeking to improve diagnostic safety, antibiotic use, and patient care should consider using these measures to reduce inappropriate diagnosis of CAP and UTI.

Excellence in Antibiotic Stewardship: A mixed methods study comparing High, Medium, and Low Performing Hospitals.

BACKGROUND: Despite antibiotic stewardship programs existing in most acute care hospitals, there continues to be variation in appropriate antibiotic use. While existing research examines individual prescriber behavior, contextual reasons for variation are poorly understood. METHODS: We conducted an explanatory, sequential mixed methods study of a purposeful sample of 7 hospitals with varying discharge antibiotic overuse. For each hospital, we conducted surveys, document analysis, and semi-structured interviews with antibiotic stewardship and clinical stakeholders. Data were analyzed separately and mixed during the interpretation phase, where each hospital was examined as a case, with findings organized across cases using a strengths, weaknesses, opportunities, and threats framework to identify factors accounting for differences in antibiotic overuse across hospitals. RESULTS: Surveys included 85 respondents. Interviews included 90 respondents (31 hospitalists, 33 clinical pharmacists, 14 stewardship leaders, 12 hospital leaders). On surveys, clinical pharmacists at hospitals with lower antibiotic overuse were more likely to report feeling: respected by hospitalist colleagues (p=0.001), considered valuable team members (p=0.001), comfortable recommending antibiotic changes (p=0.02). Based on mixed-methods analysis, hospitals with low antibiotic overuse had four distinguishing characteristics: a) robust knowledge of and access to antibiotic stewardship guidance, b) high quality clinical pharmacist-physician relationships, c) tools and infrastructure to support stewardship, and d) highly engaged Infectious Diseases physicians who advocated stewardship principles. CONCLUSION: This mixed-method study demonstrates the importance of organizational context for high performance in stewardship and suggests improving antimicrobial stewardship requires attention to knowledge, interactions, and relationships between clinical teams and infrastructure that supports stewardship and team interactions.

Antibiotic Stewardship Strategies and Their Association With Antibiotic Overuse After Hospital Discharge: An Analysis of the Reducing Overuse of Antibiotics at Discharge (Road) Home Framework.

BACKGROUND: Strategies to optimize antibiotic prescribing at discharge are not well understood. METHODS: In fall 2019, we surveyed 39 Michigan hospitals on their antibiotic stewardship strategies. The association of reported strategies with discharge antibiotic overuse (unnecessary, excess, suboptimal fluoroquinolones) for community-acquired pneumonia (CAP) and urinary tract infection (UTI) was evaluated in 2 ways: (1) all strategies assumed equal weight and (2) strategies were weighted based on the ROAD (Reducing Overuse of Antibiotics at Discharge) Home Framework (ie, Tier 1-Critical infrastructure, Tier 2-Broad inpatient interventions, Tier 3-Discharge-specific strategies) with Tier 3 strategies receiving the highest weight. RESULTS: Between 1 July 2017 and 30 July 2019, 39 hospitals with 20 444 patients (56.5% CAP; 43.5% UTI) were included. Survey response was 100%. Hospitals reported a median (interquartile range [IQR]) 12 (9-14) of 34 possible stewardship strategies. On analyses of individual stewardship strategies, the Tier 3 intervention, review of antibiotics prior to discharge, was the only strategy consistently associated with lower antibiotic overuse at discharge (adjusted incident rate ratio [aIRR] 0.543, 95% confidence interval [CI]: .335-.878). On multivariable analysis, weighting by ROAD Home tier predicted antibiotic overuse at discharge for both CAP and UTI. For diseases combined, having more weighted strategies was associated with lower antibiotic overuse at discharge (aIRR 0.957, 95% CI: .927-.987, per weighted intervention); discharge-specific stewardship strategies were associated with a 12.4% relative decrease in antibiotic overuse days at discharge. CONCLUSIONS: The more stewardship strategies a hospital reported, the lower its antibiotic overuse at discharge. However, Tier 3, or discharge-specific strategies, appeared to have the largest effect on antibiotic prescribing at discharge.

A Statewide Collaborative Quality Initiative to Improve Antibiotic Duration and Outcomes in Patients Hospitalized With Uncomplicated Community-Acquired Pneumonia.

BACKGROUND: Community-acquired pneumonia (CAP) is a common cause for hospitalization and antibiotic overuse. We aimed to improve antibiotic duration for CAP across 41 hospitals participating in the Michigan Hospital Medicine Safety Consortium (HMS). METHODS: This prospective collaborative quality initiative included patients hospitalized with uncomplicated CAP who qualified for a 5-day antibiotic duration. Between 23 February 2017 and 5 February 2020, HMS targeted appropriate 5-day antibiotic treatment through benchmarking, sharing best practices, and pay-for-performance incentives. Changes in outcomes, including appropriate receipt of 5 ± 1-day antibiotic treatment and 30-day postdischarge composite adverse events (ie, deaths, readmissions, urgent visits, and antibiotic-associated adverse events), were assessed over time (per 3-month quarter), using logistic regression and controlling for hospital clustering. RESULTS: A total of 41 hospitals and 6553 patients were included. The percentage of patients treated with an appropriate 5 ±â€…1-day duration increased from 22.1% (predicted probability, 20.9% [95% confidence interval: 17.2%-25.0%]) to 45.9% (predicted probability, 43.9% [36.8%-51.2%]; adjusted odds ratio [aOR] per quarter, 1.10 [1.07-1.14]). Thirty-day composite adverse events occurred in 18.5% of patients (1166 of 6319) and decreased over time (aOR per quarter, 0.98 [95% confidence interval: .96-.99]) owing to a decrease in antibiotic-associated adverse events (aOR per quarter, 0.91 [.87-.95]). CONCLUSIONS: Across diverse hospitals, HMS participation was associated with more appropriate use of short-course therapy and fewer adverse events in hospitalized patients with uncomplicated CAP. Establishment of national or regional collaborative quality initiatives with data collection and benchmarking, sharing of best practices, and pay-for-performance incentives may improve antibiotic use and outcomes for patients hospitalized with uncomplicated CAP.

Empiric Antibacterial Therapy and Community-onset Bacterial Coinfection in Patients Hospitalized With Coronavirus Disease 2019 (COVID-19): A Multi-hospital Cohort Study.

BACKGROUND: Antibacterials may be initiated out of concern for bacterial coinfection in coronavirus disease 2019 (COVID-19). We determined prevalence and predictors of empiric antibacterial therapy and community-onset bacterial coinfections in hospitalized patients with COVID-19. METHODS: A randomly sampled cohort of 1705 patients hospitalized with COVID-19 in 38 Michigan hospitals between 3/13/2020 and 6/18/2020. Data were collected on early (within 2 days of hospitalization) empiric antibacterial therapy and community-onset bacterial coinfections (positive microbiologic test ≤3 days). Poisson generalized estimating equation models were used to assess predictors. RESULTS: Of 1705 patients with COVID-19, 56.6% were prescribed early empiric antibacterial therapy; 3.5% (59/1705) had a confirmed community-onset bacterial infection. Across hospitals, early empiric antibacterial use varied from 27% to 84%. Patients were more likely to receive early empiric antibacterial therapy if they were older (adjusted rate ratio [ARR]: 1.04 [1.00-1.08] per 10 years); had a lower body mass index (ARR: 0.99 [0.99-1.00] per kg/m2), more severe illness (eg, severe sepsis; ARR: 1.16 [1.07-1.27]), a lobar infiltrate (ARR: 1.21 [1.04-1.42]); or were admitted to a for-profit hospital (ARR: 1.30 [1.15-1.47]). Over time, COVID-19 test turnaround time (returned ≤1 day in March [54.2%, 461/850] vs April [85.2%, 628/737], P < .001) and empiric antibacterial use (ARR: 0.71 [0.63-0.81] April vs March) decreased. CONCLUSIONS: The prevalence of confirmed community-onset bacterial coinfections was low. Despite this, half of patients received early empiric antibacterial therapy. Antibacterial use varied widely by hospital. Reducing COVID-19 test turnaround time and supporting stewardship could improve antibacterial use.

Antibiotic Overuse After Hospital Discharge: A Multi-hospital Cohort Study.

BACKGROUND: Antibiotics are commonly prescribed to patients as they leave the hospital. We aimed to create a comprehensive metric to characterize antibiotic overuse after discharge among hospitalized patients treated for pneumonia or urinary tract infection (UTI), and to determine whether overuse varied across hospitals and conditions. METHODS: In a retrospective cohort study of hospitalized patients treated for pneumonia or UTI in 46 hospitals between 1 July 2017-30 July 2019, we quantified the proportion of patients discharged with antibiotic overuse, defined as unnecessary antibiotic use, excess antibiotic duration, or suboptimal fluoroquinolone use. Using linear regression, we assessed hospital-level associations between antibiotic overuse after discharge in patients treated for pneumonia versus a UTI. RESULTS: Of 21 825 patients treated for infection (12 445 with pneumonia; 9380 with a UTI), nearly half (49.1%) had antibiotic overuse after discharge (56.9% with pneumonia; 38.7% with a UTI). For pneumonia, 63.1% of overuse days after discharge were due to excess duration; for UTIs, 43.9% were due to treatment of asymptomatic bacteriuria. The percentage of patients discharged with antibiotic overuse varied 5-fold among hospitals (from 15.9% [95% confidence interval, 8.7%-24.6%] to 80.6% [95% confidence interval, 69.4%-88.1%]) and was strongly correlated between conditions (regression coefficient = 0.85; P < .001). CONCLUSIONS: Antibiotic overuse after discharge was common and varied widely between hospitals. Antibiotic overuse after discharge was associated between conditions, suggesting that the prescribing culture, physician behavior, or organizational processes contribute to overprescribing at discharge. Multifaceted efforts focusing on all 3 types of overuse and multiple conditions should be considered to improve antibiotic prescribing at discharge.

Tocilizumab for Treatment of Mechanically Ventilated Patients With COVID-19.

BACKGROUND: Severe coronavirus disease 2019 (COVID-19) can manifest in rapid decompensation and respiratory failure with elevated inflammatory markers, consistent with cytokine release syndrome for which IL-6 blockade is an approved treatment. METHODS: We assessed effectiveness and safety of IL-6 blockade with tocilizumab in a single-center cohort of patients with COVID-19 requiring mechanical ventilation. The primary endpoint was survival probability postintubation; secondary analyses included an ordinal illness severity scale integrating superinfections. Outcomes in patients who received tocilizumab compared with tocilizumab-untreated controls were evaluated using multivariable Cox regression with propensity score inverse probability of treatment weighting (IPTW). RESULTS: 154 patients were included, of whom 78 received tocilizumab and 76 did not. Median follow-up was 47 days (range, 28-67). Baseline characteristics were similar between groups, although tocilizumab-treated patients were younger (mean: 55 vs 60 years), less likely to have chronic pulmonary disease (10% vs 28%), and had lower D-dimer values at time of intubation (median: 2.4 vs 6.5 mg/dL). In IPTW-adjusted models, tocilizumab was associated with a 45% reduction in hazard of death (HR, .55; 95% CI, .33-.90) and improved status on the ordinal outcome scale [OR per 1-level increase, .58; .36-.94). Although tocilizumab was associated with an increased proportion of patients with superinfections (54% vs 26%; P < .001), there was no difference in 28-day case fatality rate among tocilizumab-treated patients with versus without superinfection (22% vs 15%; P = .42). Staphylococcus aureus accounted for ~50% of bacterial pneumonia. CONCLUSIONS: In this cohort of mechanically ventilated COVID-19 patients, tocilizumab was associated with lower mortality despite higher superinfection occurrence.

Utility of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening in patients with acute myeloid leukemia (AML).

BACKGROUND: Current literature has demonstrated the utility of the MRSA nasal screen as a de-escalation tool to decrease unnecessary anti-MRSA antibiotic therapy. However, data on the applicability of this test in patients with hematologic malignancy is lacking. METHODS: This is a single-center, retrospective cohort study of patients with acute myeloid leukemia (AML) with or without a history of hematopoietic cell transplant (HCT), with pneumonia and MRSA nasal screening with respiratory cultures obtained. The primary outcome was to determine the negative predictive value (NPV) of the MRSA nasal screen for MRSA pneumonia. Secondary outcomes included sensitivity, specificity, positive predictive value (PPV) of the MRSA nasal screen and prevalence of MRSA pneumonia. RESULTS: Of 98 patients with AML and pneumonia, the prevalence of MRSA pneumonia was 4.1% with confirmed positive MRSA respiratory cultures observed in 4 patient cases. In patients with confirmed MRSA pneumonia, 3 had positive MRSA nasal screens while 1 had a false negative result, possibly due to a long lag time (21 days) between MRSA nasal screen and pneumonia diagnosis. Overall, the MRSA nasal screen demonstrated 75% sensitivity and 100% specificity, with a PPV of 100% and a NPV of 98.9%. CONCLUSIONS: Given the low prevalence, empiric use of anti-MRSA therapy in those AML and HCT patients with pneumonia may not be warranted in clinically stable patients. For patients in whom empiric anti-MRSA antibiotics are initiated, nasal screening for MRSA may be utilized to de-escalate anti-MRSA antibiotics in patients with AML with or without HCT.

Clinical Implications of Microbiologic Treatment Failure in the Setting of Clinical Cure of Bacterial Pneumonia.

BACKGROUND: Microbiologic cure is a common outcome in pneumonia clinical trials, but its clinical significance is incompletely understood. METHODS: We conducted a retrospective cohort study of adult patients hospitalized with bacterial pneumonia who achieved clinical cure. Rates of recurrent pneumonia and death were compared between patients with persistent growth of the index pathogen at the time of clinical cure (microbiologic failure) and those with pathogen eradication (microbiologic cure). RESULTS: Among 441 patients, 237 experienced microbiologic cure and 204 experienced microbiologic failure. Prevalences of comorbidities, ventilator dependence, and severity of acute illness were similar between groups. Patients with microbiologic failure experienced significantly higher rates of recurrent pneumonia or death following clinical cure than patients with microbiologic cure, controlling for comorbid conditions, severity of acute illness, appropriateness of empiric antibiotics, intensive care unit placement, tracheostomy dependence, and immunocompromised status (90-day multivariable adjusted odds ratio [OR], 1.56; 95% confidence interval [CI], 1.04-2.35). This association was observed among patients with pneumonias caused by Staphylococcus aureus (90-day multivariable adjusted OR, 3.69; 95% CI, 1.73-7.90). A trend was observed among pneumonias caused by nonfermenting gram-negative bacilli, but not Enterobacteriaceae or other pathogens. CONCLUSIONS: Microbiologic treatment failure was independently associated with recurrent pneumonia or death among patients with bacterial pneumonia following clinical cure. Microbiologic cure merits further study as a metric to guide therapeutic interventions for patients with bacterial pneumonia.

Current Epidemiology, Etiology, and Burden of Acute Skin Infections in the United States.

The US burden of acute skin infections is substantial. While Staphylococcus aureus and Streptococcus spp. are the most common causes, gram-negative bacteria and mixed infections can occur in some settings. These mixed infections are more likely to result in inappropriate empiric antibiotic therapy. Important challenges remain in diagnosing and treating acute skin infections.

Outpatient Treatment for COVID-19.

This JAMA Patient Page describes current medications available for outpatient treatment of COVID-19 (nirmatrelvir-ritonavir, remdesivir, and molnupiravir), their effectiveness, and how to obtain them.

A case of Q fever after liver transplantation.

Coxiella burnetii, the causative agent of Q fever, is a zoonosis that causes both acute and chronic disease in humans. Few cases have been reported in solid organ transplant recipients, and this case highlights the need to include Q fever in the differential diagnosis for fever of unknown origin in solid organ transplant hosts.

Intrahost Evolution of Methicillin-Resistant Staphylococcus aureus USA300 Among Individuals With Reoccurring Skin and Soft-Tissue Infections.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) USA300 is the leading cause of MRSA infections in the United States and has caused an epidemic of skin and soft-tissue infections. Recurrent infections with USA300 MRSA are common, yet intrahost evolution during persistence on an individual has not been studied. This gap hinders the ability to clinically manage recurrent infections and reconstruct transmission networks. METHODS: To characterize bacterial intrahost evolution, we examined the clinical courses of 4 subjects with 3-6 recurrent USA300 MRSA infections, using patient clinical data, including antibiotic exposure history, and whole-genome sequencing and phylogenetic analysis of all available MRSA isolates (n = 29). RESULTS: Among sequential isolates, we found variability in diversity, accumulation of mutations, and mobile genetic elements. Selection for antimicrobial-resistant populations was observed through both an increase in the number of plasmids conferring multidrug resistance and strain replacement by a resistant population. Two of 4 subjects had strain replacement with a genetically distinct USA300 MRSA population. DISCUSSIONS: During a 5-year period in 4 subjects, we identified development of antimicrobial resistance, intrahost evolution, and strain replacement among isolates from patients with recurrent MRSA infections. This calls into question the efficacy of decolonization to prevent recurrent infections and highlights the adaptive potential of USA300 and the need for effective sampling.

Repeated Blood Cultures in Pediatric Febrile Neutropenia: Would Following the Guidelines Alter the Outcome?

BACKGROUND: The Infectious Diseases Society of America (IDSA) guidelines recommend collecting blood cultures for the first 3 days of febrile neutropenia (FN) in the clinically stable oncology patient with persistent fevers. Nonetheless, many physicians send daily blood cultures beyond 3 days, and the impact of that practice is uncertain. PROCEDURE: We reviewed pediatric FN episodes from July 2009 to May 2014 at University of Chicago Comer Children's Hospital. For each positive culture, we determined if it was a pathogen or a contaminant. We reviewed episode and patient demographics to identify risk factors for subsequent positive blood cultures in the setting of an initially negative culture. RESULTS: We identified 381 episodes of FN in 162 patients. Of those, 87 had a positive blood culture on day 1 (21.0% incidence of bacteremia). Of 294 episodes with a negative blood culture on day 1, six (2.04%, 95% confidence interval [CI] 0.42-3.67) had a positive culture after day 3. Of those, three were pathogens (1.02%, 95%CI -0.14 to 2.18), and only one was found in a hemodynamically stable patient (0.34%, 95%CI -0.33 to 1.01) with new mucositis. In the other two patients, Escherichia coli was isolated from blood cultures after day 10 in the setting of significant hemodynamic changes. Risk factor analysis performed in stable patients yielded nonsignificant results. CONCLUSIONS: Of 294 FN episodes with an initial negative blood culture, only one episode of bacteremia occurred without hemodynamic changes past day 3, supporting the IDSA guidelines to discontinue blood cultures in stable FN patients after day 3.

Candida dubliniensis Pneumonia: A Case Report and Review of Literature.

Candida dubliniensis is an uncommon species of Candida which has been implicated in fungal pneumonia only very rarely. We present the case of a 75-year-old man with laryngeal cancer undergoing chemotherapy on broad-spectrum antibiotics and tuberculosis therapy with blood and endotracheal cultures positive for C. dubliniensis. Subsequent autopsy was performed with postmortem lung cultures positive for C. dubliniensis and lung histopathology demonstrating an invasive fungal infection. Molecular analysis of the lung tissue confirmed the identity of the fungi as C. dubliniensis. Since its discovery as a pathogen in the oral cavities of HIV-positive patients, C. dubliniensis has been identified in a wide spectrum of clinical scenarios and anatomic locations but manifests only rarely as pneumonia. This report represents a novel case of C. dubliniensis pneumonia confirmed by culture, histopathology, and molecular identification.

Inappropriate Diagnosis of Pneumonia Among Hospitalized Adults.

Importance: Little is known about incidence of, risk factors for, and harms associated with inappropriate diagnosis of community-acquired pneumonia (CAP). Objective: To characterize inappropriate diagnosis of CAP in hospitalized patients. Design, Setting, and Participants: This prospective cohort study, including medical record review and patient telephone calls, took place across 48 Michigan hospitals. Trained abstractors retrospectively assessed hospitalized patients treated for CAP between July 1, 2017, and March 31, 2020. Patients were eligible for inclusion if they were adults admitted to general care with a discharge diagnostic code of pneumonia who received antibiotics on day 1 or 2 of hospitalization. Data were analyzed from February to December 2023. Main Outcomes and Measures: Inappropriate diagnosis of CAP was defined using a National Quality Forum-endorsed metric as CAP-directed antibiotic therapy in patients with fewer than 2 signs or symptoms of CAP or negative chest imaging. Risk factors for inappropriate diagnosis were assessed and, for those inappropriately diagnosed, 30-day composite outcomes (mortality, readmission, emergency department visit, Clostridioides difficile infection, and antibiotic-associated adverse events) were documented and stratified by full course (>3 days) vs brief (≤3 days) antibiotic treatment using generalized estimating equation models adjusting for confounders and propensity for treatment. Results: Of the 17 290 hospitalized patients treated for CAP, 2079 (12.0%) met criteria for inappropriate diagnosis (median [IQR] age, 71.8 [60.1-82.8] years; 1045 [50.3%] female), of whom 1821 (87.6%) received full antibiotic courses. Compared with patients with CAP, patients inappropriately diagnosed were older (adjusted odds ratio [AOR], 1.08; 95% CI, 1.05-1.11 per decade) and more likely to have dementia (AOR, 1.79; 95% CI, 1.55-2.08) or altered mental status on presentation (AOR, 1.75; 95% CI, 1.39-2.19). Among those inappropriately diagnosed, 30-day composite outcomes for full vs brief treatment did not differ (25.8% vs 25.6%; AOR, 0.98; 95% CI, 0.79-1.23). Full vs brief duration of antibiotic treatment among patients was associated with antibiotic-associated adverse events (31 of 1821 [2.1%] vs 1 of 258 [0.4%]; P = .03). Conclusions and Relevance: In this cohort study, inappropriate diagnosis of CAP among hospitalized adults was common, particularly among older adults, those with dementia, and those presenting with altered mental status. Full-course antibiotic treatment of those inappropriately diagnosed with CAP may be harmful.