Minocycline Alone and in Combination with Polymyxin B, Meropenem, and Sulbactam against Carbapenem-Susceptible and -Resistant Acinetobacter baumannii in an In Vitro Pharmacodynamic Model.

Acinetobacter baumannii is recognized as an urgent public health threat by the Centers for Disease Control and Prevention (CDC). Current treatment options are scarce, particularly against carbapenem-resistant Acinetobacter baumannii (CRAB). We simulated the impact of minocycline standard (200 mg load + 100 mg Q12h) and high (700 mg load + 350 mg Q12h) doses, polymyxin B (2.5 mg/kg Q12h), sulbactam (1 g Q6h and 9 g/24 h as continuous infusion), and meropenem (intermittent 1 or 2 g Q8h and 6 g/24 h as continuous infusion) alone or in combination against CRAB and non-CRAB isolates by simulating human therapeutic dosing regimens in a 72-h, in vitro pharmacodynamic (IVPD) model. There were no monotherapy regimens that demonstrated bactericidal activity against the tested non-CRAB and CRAB strains. Resistance development was common in monotherapy regimens. Against the CRAB isolate, the triple combination of high-dose minocycline (fAUC/MIC 21.2), polymyxin B (fAUC/MIC 15.6), and continuous-infusion sulbactam (67% T>MIC) was the most consistently active regimen. Against non-CRAB, the triple therapy regimen of high-dose minocycline (fAUC/MIC 84.8) with continuous-infusion meropenem (100% T>MIC) and continuous-infusion sulbactam (83% T>MIC), as well as the double therapy of high-dose minocycline (fAUC/MIC 84.8) with continuous-infusion meropenem (100% T>MIC), resulted in persistently bactericidal activity. In conclusion, triple therapy with high-dose minocycline, continuous-infusion sulbactam, and polymyxin B produced the most significant kill against the carbapenem-resistant Acinetobacter baumannii, with no regrowth and minimal resistance development.

Clinical Outcomes of Patients Treated for Candida auris Infections in a Multisite Health System, Illinois, USA.

Candida auris is an emerging fungal pathogen that is typically resistant to fluconazole and is known to cause healthcare-associated outbreaks. We retrospectively reviewed 28 patients who had >1 positive culture for C. auris within a multisite health system in Illinois, USA, during May 2018-April 2019. Twelve of these patients were treated as inpatients for C. auris infections; 10 (83%) met criteria for clinical success, defined as absence of all-cause mortality, C. auris recurrence, and infection-related readmission at 30 days from the first positive culture. The other 2 patients (17%) died within 30 days. Most patients (92%) were empirically treated with micafungin. Four (14%) of 28 total isolates were resistant to fluconazole, 1 (3.6%) was resistant to amphotericin B, and 1 (3.6%) was resistant to echinocandins. Our findings describe low rates of antifungal resistance and favorable clinical outcomes for most C. auris patients.

Fluoroquinolone versus Beta-Lactam Oral Step-Down Therapy for Uncomplicated Streptococcal Bloodstream Infections.

Fluoroquinolones (FQs) are often preferred as oral step-down therapy for bloodstream infections (BSIs) due to favorable pharmacokinetic parameters; however, they are also associated with serious adverse events. The objective of this study was to compare clinical outcomes for patients who received an oral FQ versus an oral beta-lactam (BL) as step-down therapy for uncomplicated streptococcal BSIs. This multicenter, retrospective cohort study analyzed adult patients who completed therapy with an oral FQ or BL with at least one blood culture positive for a Streptococcus species from 1 January 2014 to 30 June 2019. The primary outcome was clinical success, defined as the lack of all-cause mortality, recurrent BSI with the same organism, and infection-related readmission at 90 days. A multivariable logistic regression model for predictors of clinical failure was conducted. A total of 220 patients were included, with 87 (40%) receiving an FQ and 133 (60%) receiving a BL. Step-down therapy with an oral BL was noninferior to an oral FQ (93.2% versus 92.0%; mean difference, 1.2%; 90% confidence interval [CI], -5.2 to 7.8). No differences were seen in 90-day mortality, 90-day recurrent BSI, 90-day infection-related readmission, or 90-day incidence of Clostridioides difficile-associated diarrhea. Predictors of clinical failure included oral step-down transition before day 3 (odds ratio [OR] = 5.18; 95% CI, 1.21, 22.16) and low-dose oral step-down therapy (OR = 2.74; 95% CI, 0.95, 7.90). Our results suggest that oral step-down therapy for uncomplicated streptococcal BSI with a BL is noninferior to an FQ.

Comparison of emergency department to hospital antibiograms: Influence of patient risk factors on susceptibility.

OBJECTIVES: Traditional antibiograms use local resistance patterns and susceptibility data to guide empiric antimicrobial therapy selection. However, antibiograms are rarely unit-specific and do not account for patient-specific risk factors. METHODS: This retrospective, single-center descriptive study used culture and susceptibility data from January 1 to December 31, 2016 to develop an Emergency Department (ED)-specific antibiogram and compare the antimicrobial susceptibilities of the most commonly identified organisms to the hospital antibiogram. All ED isolates were further stratified by the following risk factors that may influence antimicrobial susceptibility: age, disposition from ED, previous antimicrobial use and/or hospitalization within 30 days, and presenting location (i.e. healthcare facility residence versus community). RESULTS: A total of 2158 isolates from the ED were included: Escherichia coli (n = 1244), Klebsiella pneumoniae (n = 232), Proteus mirabilis (n = 131), Pseudomonas aeruginosa (n = 103), Staphylococcus aureus (n = 303), and Enterococcus faecalis (n = 145). There were no statistically significant differences between the ED and hospital antibiogram (n = 5739) with the exception of Escherichia coli. The hospital antibiogram overestimated Escherichia coli resistance rates for cefazolin (20% vs 15.6%, p = 0.049), ceftriaxone (9.6% vs 6.4%, p < 0.033), and ciprofloxacin (23.7% vs 15.4%, p < 0.006). There were significantly more risk factors present in patients admitted versus discharged from the ED (p < 0.001). Healthcare facility residence had the greatest influence on susceptibility, especially Escherichia coli (81.8% vs 34.9%, p < 0.001) and Proteus mirabilis (75.3% vs 33%, p < 0.001) ciprofloxacin susceptibility. CONCLUSIONS: There were no statistically significant differences between the ED and hospital antibiogram with the exception of Escherichia coli. However, development of an ED-specific antibiogram can aid physicians in prescribing appropriate empiric therapy when risk factors are included.

A Review of Combination Antimicrobial Therapy for Enterococcus faecalis Bloodstream Infections and Infective Endocarditis.

Enterococci, one of the most common causes of hospital-associated infections, are responsible for substantial morbidity and mortality. Enterococcus faecalis, the more common and virulent species, causes serious high-inoculum infections, namely infective endocarditis, that are associated with cardiac surgery and mortality rates that remained unchanged for the last 30 years. The best cures for these infections are observed with combination antibiotic therapy; however, optimal treatment has not been fully elucidated. It is the purpose of this review to highlight treatment options and their limitations, and provide direction for future investigative efforts to aid in the treatment of these severe infections. While ampicillin plus ceftriaxone has emerged as a preferred treatment option, mortality rates continue to be high, and from a safety standpoint, ceftriaxone, unlike other cephalosporins, promotes colonization with vancomycin resistant-enterococci due to high biliary concentrations. More research is needed to improve patient outcomes from this high-mortality disease.

Effect of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Alone versus MALDI-TOF MS Combined with Real-Time Antimicrobial Stewardship Interventions on Time to Optimal Antimicrobial Therapy in Patients with Positive Blood Cultures.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) decreases the time to organism identification and improves clinical and financial outcomes. The purpose of this study was to evaluate the impact of MALDI-TOF MS alone versus MALDI-TOF MS combined with real-time, pharmacist-driven, antimicrobial stewardship (AMS) intervention on patient outcomes. This single-center, pre-post, quasiexperimental study evaluated hospitalized patients with positive blood cultures identified via MALDI-TOF MS combined with prospective AMS intervention compared to a control cohort with MALDI-TOF MS identification without AMS intervention. AMS intervention included: real-time MALDI-TOF MS pharmacist notification and prospective AMS provider feedback. The primary outcome was the time to optimal therapy (TTOT). A total of 252 blood cultures, 126 in each group, were included in the final analysis. MALDI-TOF MS plus AMS intervention significantly reduced the overall TTOT (75.17 versus 43.06 h; P < 0.001), the Gram-positive contaminant TTOT (48.21 versus 11.75 h; P < 0.001), the Gram-negative infection (GNI) TTOT (71.83 versus 35.98 h; P < 0.001), and the overall hospital length of stay (LOS; 15.03 versus 9.02 days; P = 0.021). The TTOT for Gram-positive infection (GPI) was improved (64.04 versus 41.61 h; P = 0.082). For GPI, the hospital LOS (14.64 versus 10.31 days; P = 0.002) and length of antimicrobial therapy 24.30 versus 18.97 days; P = 0.018) were reduced. For GNI, the time to microbiologic clearance (51.13 versus 34.51 h; P < 0.001), the hospital LOS (15.40 versus 7.90 days; P = 0.027), and the intensive care unit LOS (5.55 versus 1.19 days; P = 0.035) were reduced. To achieve optimal outcomes, rapid identification with MALDI-TOF MS combined with real-time AMS intervention is more impactful than MALDI-TOF MS alone.

The Food and Drug Administration's (FDA's) Drug Safety Surveillance During the COVID-19 Pandemic.

INTRODUCTION: On 4 February, 2020, the Secretary of the Department of Health and Human Services declared a public health emergency related to coronavirus disease 2019 (COVID-19), and on 27 March, 2020 declared circumstances existed to justify the authorization of the emergency use of drug and biological products (hereafter, "drugs") for COVID-19. At the outset of the pandemic with uncertainty relating to the virus, many drugs were being used to treat or prevent COVID-19, resulting in the US Food and Drug Administration's (FDA's) need to initiate heightened surveillance across these drugs. OBJECTIVE: We aimed to describe the FDA's approach to monitoring the safety of drugs to treat or prevent COVID-19 across multiple data sources and the subsequent actions taken by the FDA to protect public health. METHODS: The FDA conducted surveillance of adverse event and medication error data using the FDA Adverse Event Reporting System, biomedical literature, FDA-American College of Medical Toxicology COVID-19 Toxicology Investigators Consortium Pharmacovigilance Project Sub-registry, and the American Association of Poison Control Centers National Poison Data System. RESULTS: From 4 February, 2020, through 31 January, 2022, we identified 22,944 unique adverse event cases worldwide and 1052 unique medication error cases domestically with drugs to treat or prevent COVID-19. These were from the FDA Adverse Event Reporting System (22,219), biomedical literature (1107), FDA-American College of Medical Toxicology COVID-19 Toxicology Investigator's Consortium Sub-registry (638), and the National Poison Data System (32), resulting in the detection of several important safety issues. CONCLUSIONS: Safety surveillance using near real-time data was critical during the COVID-19 pandemic because the FDA monitored an unprecedented number of drugs to treat or prevent COVID-19. Additionally, the pandemic prompted the FDA to accelerate innovation, forging new collaborations and leveraging data sources to conduct safety surveillance to respond to the pandemic.

Identification of a bacteria-produced benzisoxazole with antibiotic activity against multi-drug resistant Acinetobacter baumannii.

The emergence of multi-drug resistant pathogenic bacteria represents a serious and growing threat to national healthcare systems. Most pressing is an immediate need for the development of novel antibacterial agents to treat Gram-negative multi-drug resistant infections, including the opportunistic, hospital-derived pathogen, Acinetobacter baumannii. Herein we report a naturally occurring 1,2-benzisoxazole with minimum inhibitory concentrations as low as 6.25 µg ml-1 against clinical strains of multi-drug resistant A. baumannii and investigate its possible mechanisms of action. This molecule represents a new chemotype for antibacterial agents against A. baumannii and is easily accessed in two steps via de novo synthesis. In vitro testing of structural analogs suggest that the natural compound may already be optimized for activity against this pathogen. Our results demonstrate that supplementation of 4-hydroxybenzoate in minimal media was able to reverse 1,2-benzisoxazole's antibacterial effects in A. baumannii. A search of metabolic pathways involving 4-hydroxybenzoate coupled with molecular modeling studies implicates two enzymes, chorismate pyruvate-lyase and 4-hydroxybenzoate octaprenyltransferase, as promising leads for the target of 3,6-dihydroxy-1,2-benzisoxazole.

Impact of Mandatory Infectious Diseases Consultation and Real-time Antimicrobial Stewardship Pharmacist Intervention on Staphylococcus aureus Bacteremia Bundle Adherence.

BACKGROUND: The purpose of this study was to evaluate the impact of infectious diseases consultation (IDC) and a real-time antimicrobial stewardship (AMS) review on the management of Staphylococcus aureus bacteremia (SAB). METHODS: This retrospective study included adult inpatients with SAB from January 2016 to December 2018 at 7 hospitals. Outcomes were compared between 3 time periods: before mandatory IDC and AMS review (period 1), after mandatory IDC and before AMS review (period 2), and after mandatory IDC and AMS review (period 3). The primary outcome was bundle adherence, defined as appropriate intravenous antimicrobial therapy, appropriate duration of therapy, appropriate surveillance cultures, echocardiography, and removal of indwelling intravenous catheters, if applicable. Secondary end points included individual bundle components, source control, length of stay (LOS), 30-day bacteremia-related readmission, and in-hospital all-cause mortality. RESULTS: A total of 579 patients met inclusion criteria for analysis. Complete bundle adherence was 65% in period 1 (n = 241/371), 54% in period 2 (n = 47/87), and 76% in period 3 (n = 92/121). Relative to period 3, bundle adherence was significantly lower in period 1 (odds ratio [OR], 0.58; 95% confidence interval [CI], 0.37-0.93; P = .02) and period 2 (OR, 0.37; 95% CI, 0.20-0.67; P = .0009). No difference in bundle adherence was noted between periods 1 and 2. Significant differences were seen in obtaining echocardiography (91% vs 83% vs 100%; P < .001), source control (34% vs 45% vs 45%; P = .04), and hospital LOS (10.5 vs 8.9 vs 12.0 days; P = .01). No differences were noted for readmission or mortality. CONCLUSIONS: The addition of AMS pharmacist review to mandatory IDC was associated with significantly improved quality care bundle adherence.

Predictors of Time to Effective and Optimal Antimicrobial Therapy in Patients With Positive Blood Cultures Identified via Molecular Rapid Diagnostic Testing.

Antimicrobial stewardship (AMS) programs integrated with rapid diagnostic tests optimize patient outcomes and reduce time to effective therapy (TTET) and time to optimal therapy (TTOT). This study identifies predictors of TTET and TTOT among patients with positive blood cultures and identifies limitations to current TTOT definitions and outcomes.

Comparative Effectiveness of Exclusive Exposure to Nafcillin or Oxacillin, Cefazolin, Piperacillin/Tazobactam, and Fluoroquinolones Among a National Cohort of Veterans With Methicillin-Susceptible Staphylococcus aureus Bloodstream Infection.

OBJECTIVE: Beta-lactam antibiotics are recommended as first-line for treatment of methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia. The objective of this study was to compare effectiveness of anti-MSSA therapies among bacteremia patients exclusively exposed to 1 antimicrobial. METHOD: This was a national retrospective cohort study of patients hospitalized in Veterans Affairs medical centers with MSSA bacteremia from January 1, 2002, to October 1, 2015. Patients were included if they were treated exclusively with nafcillin, oxacillin, cefazolin, piperacillin/tazobactam, or fluoroquinolones (moxifloxacin and levofloxacin). We assessed 30-day mortality, time to discharge, inpatient mortality, 30-day readmission, and 30-day S. aureus reinfection. Hazard ratios (HRs) and 95% confidence intervals (CI) were calculated using propensity-score (PS) matched Cox proportional hazards regression model. RESULTS: When comparing nafcillin/oxacillin (n = 105) with cefazolin (n = 107), 30-day mortality was similar between groups (PS matched n = 44; HR, 0.67; 95% CI, 0.11-4.00), as were rates of the other outcomes assessed. As clinical outcomes did not vary between nafcillin/oxacillin and cefazolin, they were combined for comparison with piperacillin/tazobactam (n = 113) and fluoroquinolones (n = 103). Mortality in the 30 days after culture was significantly lower in the nafcillin/oxacillin/cefazolin group compared with piperacillin/tazobactam (PS matched n = 48; HR, 0.10; 95% CI, 0.01-0.78), and similar when compared with fluoroquinolones (PS matched n = 32; HR, 1.33; 95% CI, 0.30-5.96). CONCLUSIONS: In hospitalized patients with MSSA bacteremia, no difference in mortality was observed between nafcillin/oxacillin and cefazolin or fluoroquinolones. However, higher mortality was observed with piperacillin/tazobactam as compared with nafcillin/oxacillin/cefazolin, suggesting it may not be as effective as a monotherapy in MSSA bacteremia.

Predictors of Clostridioides difficile recurrence across a national cohort of veterans in outpatient, acute, and long-term care settings.

PURPOSE: The greatest challenge in treating Clostridioides difficile infection (CDI) is disease recurrence, which occurs in about 20% of patients, usually within 30 days of treatment cessation. We sought to identify independent predictors of first recurrence among a national cohort of veterans with CDI. METHODS: We conducted a case-control study among acute and long-term care Veterans Affairs (VA) inpatients and outpatients with a first CDI episode (positive stool sample for C. difficile toxin[s] and receipt of at least 2 days of CDI treatment) between 2010 and 2014. Cases experienced first recurrence within 30 days from the end of treatment. Controls were those without first recurrence matched 4:1 to cases on year, facility, and severity. Multivariable conditional logistic regression was used to identify predictors of first recurrence. RESULTS: We identified 32 predictors of first recurrence among 974 cases and 3,896 matched controls. Significant predictors included medication use prior to (probiotics, fluoroquinolones, laxatives, third- or fourth-generation cephalosporins), during (first- or second-generation cephalosporins, penicillin/amoxicillin/ampicillin, third- and fourth-generation cephalosporins), and after CDI treatment (probiotics, any antibiotic, proton pump inhibitors [PPIs], and immunosuppressants). Other predictors included current biliary tract disease, malaise/fatigue, cellulitis/abscess, solid organ cancer, medical history of HIV, multiple myeloma, abdominal pain, and ulcerative colitis. CONCLUSION: In a large national cohort of outpatient and acute and long-term care inpatients, treatment with certain antibiotics, PPIs, immunosuppressants, and underlying disease were among the most important risk factors for first CDI recurrence.

Biofilm prevention concentrations (BPC) of minocycline compared to polymyxin B, meropenem, and amikacin against Acinetobacter baumannii.

Infections caused by Acinetobacter baumannii are difficult to treat as they are often multidrug resistant (MDR) and frequently form biofilms. We investigated the activities of minocycline, polymyxin B, meropenem, and amikacin against diverse Acinetobacter baumannii strains with biofilm formation classified as weak versus moderate/strong. At clinically achievable concentrations, minocycline prevented biofilm formation for 96% of isolates versus 54% for polymyxin B, 29% for meropenem and 29% for amikacin. Minocycline and polymyxin B demonstrated highest in vitro activity against A. baumannii and prevented biofilm formation for a majority of isolates.

Interplay between Rapid Diagnostic Tests and Antimicrobial Stewardship Programs among Patients with Bloodstream and Other Severe Infections.

BACKGROUND: Antimicrobial stewardship programs (ASPs) aim to provide optimal antimicrobial therapy to patients quickly to improve the likelihood of overcoming infection while reducing the risk of adverse effects. Rapid diagnostic tests (RDTs) for infectious diseases have become an integral tool for ASPs to achieve these aims. CONTENT: This review explored the demonstrated clinical value of longer-standing technologies and implications of newer RDTs from an antimicrobial stewardship perspective. Based on available literature, the focus was on the use of RDTs in bloodstream infections (BSIs), particularly those that perform organism identification and genotypic resistance detection, phenotypic susceptibility testing, and direct specimen testing. Clinical implications of rapid testing among respiratory, central nervous system, and gastrointestinal infections are also reviewed. SUMMARY: Coupling RDTs with ASPs facilitates the appropriate and timely use of test results, translating into improved patient outcomes through optimization of antimicrobial use. These benefits are best demonstrated in the use of RDT in BSIs. Rapid phenotypic susceptibility testing offers the potential for early pharmacokinetic/pharmacodynamic optimization, and direct specimen testing on blood may allow ASPs to initiate appropriate therapy and/or tailor empiric therapy even sooner than other RDTs. RDTs for respiratory, central nervous system, and gastrointestinal illnesses have also shown significant promise, although more outcome studies are needed to evaluate their full impact.

Communicating with Facility Leadership; Metrics for Successful Antimicrobial Stewardship Programs (Asp) in Acute Care and Long-Term Care Facilities.

Up to 50% of hospital-administered and 70% of nursing home-administered antimicrobials are inappropriately prescribed. There is a great need to focus local, national and global efforts on appropriate antibiotic use. Formal programs dedicated to appropriate antibiotic use have been established in most US hospitals. These antimicrobial stewardship programs (ASP) exist to ensure that the correct drug, dose and duration of an antimicrobial is given, and only when there is a true bacterial infection (as opposed to bacterial colonization or a viral infection). These programs increase patient safety and reduce unintended consequences including Clostridium difficile infections, medication-related adverse effects, and antimicrobial resistance. Most of these programs are co-lead by an interdisciplinary team consisting of an infectious diseases (ID) pharmacist and an ID physician. However, consistent and meaningful metrics to study the impact of ASPs have not been elucidated. With the Joint Commission Standards for Acute Care facilities, and Centers for Medicare and Medicare (CMS) for long-term care facilities making antimicrobial stewardship (AMS) a condition of participation, both facilities will be scrambling to create appropriate quality care indicators to measure program success. One major theme across all healthcare settings is that ASPs must collaborate with facility leadership and key stakeholders at each institution in order to have an impactful benefit on patient quality of care, and safety. It is the purpose of this review to offer several economic, process, and patient-outcome measurements for ASP to optimally communicate with facility leadership.

Predictors of Mortality Among a National Cohort of Veterans With Recurrent Clostridium difficile Infection.

BACKGROUND: Though recurrent Clostridium difficile infection (CDI) is common and poses a major clinical concern, data are lacking regarding mortality among patients who survive their initial CDI and have subsequent recurrences. Risk factors for mortality in patients with recurrent CDI are largely unknown. METHODS: Veterans Affairs patients with a first CDI (stool sample with positive C. difficile toxin(s) and ≥2 days CDI treatment) were included (2010-2014). Subsequent recurrences were defined as additional CDI episodes ≥14 days after the stool test date and within 30 days of the end of treatment. A matched (1:4) case-control analysis was conducted using multivariable conditional logistic regression to identify predictors of all-cause mortality within 30 days of the first recurrence. RESULTS: Crude 30-day all-cause mortality rates were 10.6% for the initial CDI episode, 8.3% for the first recurrence, 4.2% for the second recurrence, and 5.9% for the third recurrence. Among 110 cases and 440 controls, 6 predictors of mortality were identified: use of proton pump inhibitors (PPIs; odds ratio [OR], 3.86; 95% confidence interval [CI], 2.14-6.96), any antibiotic (OR, 3.33; 95% CI, 1.79-6.17), respiratory failure (OR, 8.26; 95% CI, 1.71-39.92), congitive dysfunction (OR, 2.41; 95% CI, 1.02-5.72), nutrition deficiency (OR, 2.91; 95% CI, 1.37-6.21), and age (OR, 1.04; 95% CI, 1.01-1.07). CONCLUSIONS: In our national cohort of Veterans, crude mortality decreased by 44% from the initial episode to the third recurrence. Treatment with antibiotics, use of PPIs, and underlying comorbidities were important predictors of mortality in recurrent CDI. Our study assists health care providers in identifying patients at high risk of death after CDI recurrence.

Assessments of Opportunities to Improve Antibiotic Prescribing in an Emergency Department: A Period Prevalence Survey.

INTRODUCTION: Approximately 30% of all outpatient antimicrobials are inappropriately prescribed. Currently, antimicrobial prescribing patterns in emergency departments (ED) are not well described. Determining inappropriate antimicrobial prescribing patterns and opportunities for interventions by antimicrobial stewardship programs (ASP) are needed. METHODS: A retrospective chart review was performed among a random sample of non-admitted, adult patients who received an antimicrobial prescription in the ED from January 1 to December 31, 2015. Appropriateness was measured using the Medication Appropriateness Index, and was based on provider adherence to local guidelines. Additional information collected included patient characteristics, initial diagnoses, and other chronic medication use. RESULTS: Of 1579 ED antibiotic prescriptions in 2015, we reviewed a total of 159 (10.1%) prescription records. The most frequently prescribed antimicrobial classes included penicillins (22.6%), macrolides (20.8%), cephalosporins (17.6%), and fluoroquinolones (17.0%). The most common indications for antibiotics were bronchitis or upper respiratory tract infection (URTI) (35.1%), followed by skin and soft tissue infection (SSTI) (25.0%), both of which were the most common reason for unnecessary prescribing (28.9% of bronchitis/URTIs, 25.6% of SSTIs). Of the antimicrobial prescriptions reviewed, 39% met criteria for inappropriateness. Among 78 prescriptions with a consensus on appropriate indications, 13.8% had inappropriate dosing, duration, or expense. CONCLUSION: Consistent with national outpatient prescribing, inappropriate antibiotic prescribing in the ED occurred in 39% of cases with the highest rates observed among patients with bronchitis, URTI, and SSTI. Antimicrobial stewardship programs may benefit by focusing on initiatives for these conditions among ED patients. Moreover, creation of local guideline pocketbooks for these and other conditions may serve to improve prescribing practices and meet the Core Elements of Outpatient Stewardship recommended by the Centers for Disease Control and Prevention.