2026 Southeastern Residency Conference

Title: Evaluation of Early Onset Severe Treatment-related Adverse Events for Fluoropyrimidine-based Chemotherapy
Authors: Alexandria Rakestraw, Alex Balkcom, Rodna Larson
Background:
Fluoropyrimidines such as 5-fluorouracil (5-FU) and capecitabine are commonly used in the treatment of solid tumors. Fluoropyrimidines work by inhibiting thymidylate synthase and incorporating the metabolites into DNA synthesis, disrupting the creation of cancerous cells.
The toxicities of fluoropyrimidines are typically seen within the first few cycles of treatment. Toxicities can occur due to the mechanism of action of fluoropyrimidines or can occur due to genetic mutations but can be enhanced by genetic mutations. Fluoropyrimidines are metabolized by dihydropyrimidine dehydrogenase. Dose reductions are based on variants to avoid potential accumulation and therefore potential toxicities.
This retrospective chart review was designed to identify CTCAE grade 3-5 toxicities in patients receiving fluoropyrimidine-based treatments, explain dose modifications secondary to genotypic variation, and understand the current practice of genotype testing prior to receiving these chemotherapeutic agents.
Methods:
This single-center, retrospective, observational chart-review was conducted at our institution from January 1, 2023, to February [RA1] 1, 2026. Adults >18 were eligible to be included in this study if they received 5-FU or capecitabine for any solid tumor and if the first dose of either medication was given within the study period. Patients were excluded from the study if the patient was being treated in a clinical trial.
The primary objective of the study was to determine the incidence and onset of grade 3-5 fluoropyrimidine-related toxicity within the first three cycles of treatment in correlation with DPYD genotype status. The specified narrowed toxicities include diarrhea, mucositis, cardiotoxicity, palmar plantar erythrodysesthesia, and pancytopenia (thrombocytopenia and neutropenia). Secondary endpoints included identification of genotypic variants, retrospective dose adjustments, time to death, and genotype testing turnaround times.
Results:
Among 85 patients treated with fluoropyrimidine-based chemotherapy (5-FU, n=51; capecitabine, n=34), DPYD genetic testing rates were low overall, yet patients tested prior to treatment initiation experienced a 59% reduction in grade 3+ toxicity events compared to untested patients (10.0% vs 24.6%, RR=0.41).
Conclusions: 
These data suggest that pre-treatment DPYD screening may reduce severe fluoropyrimidine-related toxicity, though the difference did not reach statistical significance given the limited sample size. Testing is available as a blood draw that has an average 9-day turnaround time.
  

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Title: Patient-Reported Outcomes with Semaglutide Sublingual Suspension for Wellness: A Prospective Observational Study.  

Authors: Jonathan Reynolds; Brandon Sucher  

Background:  
Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have increased in use for the treatment of obesity. This class of medications is associated with weight loss through activation of GLP-1 receptors, which delays gastric emptying and increases satiety. While effective for weight loss, injectable GLP-1 RAs are associated with gastrointestinal side effects, high cost, and the need for subcutaneous injections. In December 2025, semaglutide 25 mg oral tablets were approved by the FDA for the treatment of obesity, providing an alternative formulation for patients. The OASIS-4 clinical trial evaluated the use of semaglutide 25 mg oral tablets dosed once daily for 64 weeks in overweight or obese adults.  At the conclusion of this study, the mean percent change in body weight from baseline to week 64 was -13.9%, and the proportion of patients with a weight loss greater than 5% was 79.2%. The most common adverse effects were nausea (46.6%), vomiting (30.9%), constipation (20.1%), dyspepsia (18.1%), and diarrhea (17.6%).  Allergic reactions occurred in 3.9% of patients. Health care providers have prescribed compounded semaglutide sublingual (SL) suspension as an alternative to injectable GLP-1 RAs.  This study aims to evaluate patient-reported outcomes from patients prescribed compounded semaglutide SL suspension.  

Methods:  
This prospective observational study utilized patient reported outcomes obtained from patients prescribed compounded semaglutide SL suspension from March 2025 to February 2026.  All adult patients who received a prescription for compounded semaglutide SL suspension within a network of 20 compounding pharmacies were eligible. Eligible patients were emailed a link to complete a patient-reported outcome measure (PROM). Patients who did not initially complete the PROM received up to two reminder emails. There were no exclusion criteria for this study. The primary endpoint was the mean percent change in body weight from baseline. Secondary endpoints included overall satisfaction, post-meal fullness, adverse drug reactions, allergic reactions, and the proportion of patients achieving weight loss greater than 5%. Descriptive statistics were used to report data. 

Results:
A total of 382 PROMs were emailed to patients, and 47 responses were received (12.3% response rate). The median dose reported was 4 mg SL once daily, and the median duration of therapy was 2 to 3 months.  The mean percent change in weight was -1.9%.  The median overall satisfaction reported was “somewhat satisfied,” and the median post-meal fullness was “moderately full.” Of the 47 patients, 8 (17%) achieved a weight loss greater than 5%. Two patients (4%) reported adverse reactions. One patient experienced constipation, headache, and fatigue, while the second patient experienced tooth sensitivity. Two patients experienced allergic reactions (4%), with one resulting in treatment discontinuation. One patient reported difficulty performing daily activities. The allergic reactions reported were not life-threatening and did not require hospitalization.  

Conclusion: 
Compounded semaglutide SL suspension at a median dose of 4 mg once daily was associated with a weight loss of 1.9% over a median duration of 2 to 3 months. The proportion of patients achieving weight loss greater than 5% was 17%. Patients reported a median level of overall satisfaction as “somewhat satisfied,” and a median post-meal fullness of feeling “moderately full.” Compounded semaglutide SL suspension demonstrated a favorable safety profile with a low incidence of reported adverse effects (4%) and allergic reactions (4%). While some benefit was seen, higher doses and a longer duration of compounded semaglutide SL suspension may demonstrate more favorable patient-reported outcomes.

Clinical Management and Outcomes in Patients with Coagulase-negative Staphylococcus spp. in Lone Blood Culture Sets
Benjamin K Battle, Andrew B. Watkins
FMOL Health | St. Dominic
Background/Purpose:
Blood cultures remain the standard for diagnosis of bloodstream infections, but blood culture contamination may lead to inappropriate antimicrobial use and increased risk to patients. Contaminants are often skin flora organisms, and coagulase-negative staphylococci (CoNS) are the most commonly identified microorganisms found in contaminated blood cultures. Differentiating contaminants from true pathogens proves a challenge as these microorganisms could potentially cause true infection. This diagnostic uncertainty and desire to treat may lead to unnecessary or inappropriate antibiotic use and/or Infectious Diseases (ID) consults, which result in clinical and economic burdens for the patient and hospital. St. Dominic Hospital has placed an emphasis on reducing blood culture contamination based on an increase in contamination rates over the last year. This study seeks to characterize the clinical management and outcomes of patients with CoNS growing in lone blood culture sets at St. Dominic Hospital, as well as to analyze overall contamination trends and financial impacts of these potential contamination events.
Methodology:
This single-center retrospective observational cohort study includes patients admitted to St. Dominic Hospital from January 1, 2025, to August 31, 2025, that are of at least eighteen years of age with CoNS on one set of blood cultures. Patients with blood cultures positive for Staphylococcus lugdunensis or prior blood cultures with CoNS in multiple sets during admission are excluded. The primary objective is to evaluate the use of antibiotics in patients with CoNS in lone blood culture sets. The secondary outcomes include reviewing the overall trend in hospital blood culture contamination rates, frequency of infectious diseases consults, costs attributable to potential contamination events, impact of contamination on pharmacist workload, and outcomes between patients receiving antibiotics for greater than three days compared to those receiving antibiotics for less than three days.
Results:
A total of 100 patients were included for analysis, with 56 (56%) receiving antibiotics for coagulase-negative Staphylococci spp. in lone blood culture sets, vancomycin serving as the most prevalent antibiotic administered. In the scope of hospital contamination rates, a total of 409 blood cultures in 2025 were characterized as contaminants, accounting for 2.22% of the total blood culture collections. There was no significant difference in mortality regarding patients that received antibiotics for three days or less when compared to patients that received a duration of antibiotics exceeding three days; however, patients receiving a short duration of antibiotics had a significantly shorter length of stay. Infectious disease consults were ordered in 39 patients, with recommendations for ceasing antibiotic use in 19 of the 39 consults. Costs attributable to contamination events were approximately $107,000 per year for the hospital. The increase in pharmacist workload on vancomycin management for patients with potential contaminations neared 18 pharmacist hours per year.
Conclusions:
Of the patients with CoNS in one of two blood culture sets, vancomycin was the primary agent utilized. The estimated costs attributable to contaminated blood culture sets were primarily driven by laboratory costs. Extended duration of antibiotics did not show improvement in mortality, and shorter treatment durations were associated with overall decreased lengths of stay. Future considerations will be educating on identify potentially contaminated blood cultures, and informing care providers on the outcomes of this study in regards to length of stay and mortality.

Background: Methicillin- resistant Staphylococcus aureus (MRSA) nasal Polymerase Chain Reaction (PCR) screening is an evidenced based diagnostic tool that can guide decisions regarding the need for anti-MRSA therapy. This evaluation aims to assess the correlation between positive nasal PCR results and culture confirmed Staphylococcus aureus infections. The utility of this screening method will be assessed for skin and soft tissue infections (SSTIs), bacteremia, wound, and urine cultures. These findings may help determine if the use of nasal PCR can be expanded beyond pneumonia to serve as a tool for guiding antimicrobial therapy in suspected MRSA infections at our institution.   

Methods: This is a single-center, retrospective study conducted at a 312-bed academic teaching hospital. Hospitalized patients 18 years of age and older who had a positive nasal PCR screening with a corresponding blood, urine, and wound culture outcomes. The primary outcome is to evaluate whether nasal PCR screening demonstrates a predictive value in relation to culture-confirmed Staphylococcus aureus infections. The data will be grouped for each set of cultures and will determine a negative predictive value. The study protocol is designated exempt from review by the Hospital Corporation of America (HCA) Institutional Review Board (IRB).  
 
Results: Based on the blood, urine, and wound culture data, the wound data had the greatest negative predictive value. Overall, 1000 patients were screened, 495 patients were excluded due to the lack of additional body sources. Out of the 505 patients, 52 were excluded due to lacking a blood, urine, or wound culture. There were 453 patients that were then included overall in the data collection. Blood cultures had a negative predictive value of 68.5%, urine cultures 66.1%, and wound cultures 76.2%. 
 
Conclusion: Based on the results from our institution there is correlation that having a negative MRSA Nasal PCR would likely result in negative MRSA/MSSA blood, wound, or urine cultures. The highest NPV was for wound cultures at 76.2%. Further research is needed to assess a larger population and potential impact of antimicrobial agents initiated prior to MRSA Nasal PCR for future studies. 

Title: Micafungin Treatment Failure in Obese Patients: Standard versus Body Mass Index-Adjusted Dosing Regimens

Authors: Helene Gao, Zachary Halbig, Caroline Gresham, Qian Zhong
Piedmont Athens Regional Medical Center - Athens, GA

Background: Obesity (BMI ≥30 kg/m²) affects more than 40% of adults in the United States and is associated with altered pharmacokinetics, creating uncertainty around optimal antifungal dosing. Micafungin, an echinocandin, is commonly used for invasive Candida infections, with standard dosing recommendations of 100-150 mg daily. However, pharmacokinetic and pharmacodynamic studies suggest that higher doses may be necessary in obese patients to achieve adequate drug exposure. Despite these findings, clinical outcome data supporting dose adjustments remain limited. Existing studies have largely been small, model‑based, or lacking comparison groups, leaving the real-world clinical impact of higher micafungin dosing unclear. This study aimed to compare clinical outcomes in obese adults receiving BMI-adjusted micafungin dosing (150-200 mg daily) versus standard dosing, with a primary focus on treatment failure.

Methods: This IRB-exempt, single-center, retrospective study evaluated obese adult patients admitted to Piedmont Athens Regional who received micafungin for ≥3 days as empiric or definitive antifungal therapy. The BMI-dose-adjusted group consisted of 19 randomly selected patients admitted between October 1, 2020, and October 30, 2025, with a cohort of 19 obese patients receiving standard micafungin dosing. Exclusion criteria included outpatient micafungin initiation, missing weight data, dose changes after ≥2 days, or <3 days of therapy. Data collected included demographics, comorbidities,infection‑related risk factors, key laboratory values, and micafungin treatment characteristics. Clinical variables evaluated included critical‑care interventions, hemodynamic support, and the presence of polymicrobial infection. The primary outcome was treatment failure, defined as all‑cause inpatient mortality or transition to comfort care before discharge. Secondary outcomes included micafungin duration, total hospital length of stay, and occurrence of adverse drug events involving hepatic, renal, or hematologic function. Categorical variables were analyzed using Chi‑squared or Fisher’s exact testing as appropriate, and continuous variables were analyzed using the Mann‑Whitney U test. A multivariable logistic regression was performed to adjust for confounders.

Results: Unadjusted outcomes revealed that treatment failure occurred in 36.8% of patients in the BMI-adjusted group and 42.1% in the standard-dose group (OR=1.25, 95% CI=0.34-4.59; p=0.74). The median duration of micafungin therapy was 5 days in the BMI-adjusted group and 7 days in the standard-dose group (p=0.12), while median hospital length of stay was 16 versus 23 days, respectively (p=0.11). Adverse drug reactions occurred in 36.8% of BMI-adjusted patients and 26.3% of standard-dose patients (p = 0.49). After adjusting for confounders, including SOFA score, number of comorbidities, and polymicrobial infection, there was a trend toward fewer treatment failures in the BMI-adjusted dosing group (OR=0.22, 95% CI=0.03-1.58;p=0.13). Within the observed range of SOFA scores, each 1-point increase within 24 hours of micafungin initiation was associated with approximately 40% increased odds of treatment failure (OR=1.40, 95%CI=1.12-2.47; p=0.002). In exploratory subgroup analyses, BMI-adjusted dosing was associated with 45% lower odds of treatment failure in ICU patients (OR=0.55, 95% CI=0.12-2.47; p=0.43) and 44% lower odds in patients with candidiasis (OR=0.56, 95% CI=0.07-4.76; p=0.59).

Conclusions: In obese adults receiving micafungin, BMI-adjusted dosing was not associated with a statistically significant difference in treatment failure compared with standard dosing. However, accounting for confounders, the analysis demonstrated numerically lower odds of treatment failure with BMI-adjusted dosing, with only SOFA score remaining significantly associated with treatment failure. Furthermore, exploratory subgroup analyses showed a consistent directional association favoring BMI-adjusted therapy. Limitations include the retrospective design, small sample size, and limited power to detect differences in outcomes. Larger, prospective studies are warranted to further evaluate the clinical effectiveness and safety of BMI-adjusted micafungin dosing, particularly in ICU patients.

Title: Effectiveness of Amoxicillin-Clavulanate for the Treatment of Extended-Spectrum β-Lactamase-producing Enterobacterales (ESBL-E) Urinary Tract Infection

Author: Haseeb Ahmed, Nicholas Rosen, Ryan Tilton, Olivia Randazza, John Williamson, Charles Hartis, Michael E DeWitt, Alexandria Taylor, Jennifer J Wenner, Mary Banoub

Background: Urinary tract infections (UTIs) are among the most common bacterial infections worldwide, with Enterobacterales being the predominant pathogens. The rise in prevalence of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) has led to increased antimicrobial resistance and recurrence rates. This prompts evaluation of alternative treatments such as amoxicillin-clavulanate, in which clavulanate may restore amoxicillin activity against common ESBL enzymes. The IDSA 2024 Antimicrobial-Resistant Gram-Negative guidelines recommend against its use but fail to cite high-quality evidence studying its efficacy in UTI caused by ESBL-E. Other studies, limited by small sample size, suggest clinical efficacy of amoxicillin-clavulanate in the treatment of UTI caused by ESBL-E. This study attempts to bolster the pool of data showing amoxicillin-clavulanate can be as effective as standard of care (SOC) antibiotics for treatment of UTI caused by ESBL-E.

Methods: This multi-site, retrospective cohort study is approved by the Institutional Review Board. Adult patients (≥18 years) with either uncomplicated or complicated UTI with a urine culture positive for ESBL-E (confirmed with susceptibility testing) treated between April 1, 2024, and July 1, 2025, at Atrium Health Wake Forest Baptist facilities were included. Patients must have received at least 72 hours of amoxicillin-clavulanate or SOC therapy. Patients were excluded if they had concurrent bacterial infections, polymicrobial urine cultures, a previous UTI within 90 days already captured in the dataset, anatomic urinary tract abnormalities or instrumentation, renal abscesses, prostatitis, receive in-vitro active antibiotic lead-in therapy for >50% of treatment duration, were immunosuppressed or use methenamine or antibiotics for prophylaxis. The primary endpoint is clinical failure within 90 days, defined as retreatment with antibiotics and either recurrence of UTI symptoms or a repeat urine culture positive for the same organism as the index infection. Secondary endpoints include time to clinical failure and recurrence of resistant organisms (carbapenem-resistant Enterobacterales, SOC-resistant, or amoxicillin-clavulanate-resistant strains) within 90 days. Chi-square or Fisher’s exact tests tested categorical variables, and t-tests or Mann-Whitney U tests will test continuous variables. Kaplan-Meier survival analysis and Cox regression modeling will assess time-to-event outcomes, and multivariable analysis will be used to identify patient factors associated with clinical failure.

Results: A total of 447 patients were screened, of whom 274 patients met inclusion criteria and were analyzed. Fifty-four patients were included in the amoxicillin-clavulanate group, while 220 patients were included in the SOC group. No statistically significant difference was observed in the primary outcome of treatment failure between the SOC and amoxicillin-clavulanate groups (p = 0.11). Patients with prior history of ESBL infection had more than twice the odds of treatment failure (OR 2.09; p = 0.04), a finding that remained significant after adjustment for antibiotic selection and type of UTI (OR 2.11, p = 0.047). Additionally, the use of sulfamethoxazole-trimethoprim for treatment of the index infection was associated with an 82% reduction in clinical failure compared to amoxicillin-clavulanate (p = 0.01).

Conclusions: Among patients treated with antibiotics for urinary tract infection caused by ESBL-producing Enterobacterales species, we were unable to detect a difference in treatment failure within 90 days between amoxicillin-clavulanate and SOC. This indicates that within the limits of this study, amoxicillin-clavulanate may have comparable effectiveness to other agents used to treat urinary tract infections caused by these resistant organisms.

Authors: Emily Gunselman; Linda Johnson; Rachel Anderson; Bradley Proctor


Background/Purpose: Asymptomatic bacteriuria (ASB) is defined as “the presence of one or more species of bacteria growing in the urine at specified quantitative counts (>105 colon-forming units [CFU]/mL or >108 CFU/L), irrespective of the presence of pyuria, in the absence of signs or symptoms attributable to urinary tract infection (UTI).”.1 Urinary tract infections (UTIs) are a clinical syndrome that should be diagnosed based on symptoms such as dysuria, urgency, frequency, suprapubic pain, flank pain, and costovertebral angle tenderness  with or without systemic signs of infection such as fever, chills, rigors or hemodynamic instability.2 The Infectious Diseases Society of America (IDSA) recommends against screening for and treating ASB, except in pregnant patients or prior to a planned urologic procedure.1 Treating ASB in patients, aside from the aforementioned exceptions, has shown lack of benefit and has also lead to increased risk of harm including: development of symptomatic UTI, colonization with multi-drug resistant gram negative rods, and increased risk of developing Clostridiodes difficile infection (CDI).3,4,5 The Emergency Department (ED) is the most common location for the ordering of urine cultures and early treatment for a suspected UTI. In August of 2025, CHI Memorial Hospital approved an Expected Practice document providing leadership support to not treat ASB.6 Additionally, a guidance document on the management of UTIs was created which detailed empiric treatment recommendations with regards to drug, route, dose, and duration based on national guidelines as well as local antibiogram data for both patients discharging from the ED and those being admitted. Didactic education was provided to the ED clinicians and the guidance documents were made available. The goal of this project was to evaluate appropriateness of ED antibiotic use for ASB and suspected urinary tract infections pre- and post- stewardship intervention. 


Methods: This is a single-center, IRB approved, quasi-experimental study. Adult patients seen in the ED with positive urine cultures showing a uropathogen were included. Patients were excluded if they had an outpatient diagnosis of UTI, another suspected source of infection, or neutropenic fever. The primary outcome of this study is to evaluate the appropriateness of empiric antibiotic therapy pre- and post- intervention. Secondary outcomes include safety of intervention, new positive cultures showing resistant organism growth, CDI, and re-presentation to the ED with the same diagnosis within 30 days.

Results:
Primary Outcome: Appropriateness of empiric antibiotic treatment choice for UTI did not improve post-intervention. However, the number of patients who had ASB and received antibiotics did decrease post-intervention.
Secondary Outcomes: There was no shown difference in development of symptomatic UTI, development of CDI, or re-presentation to the ED within 30 days for the same diagnosis between patients that were appropriately treated vs not. However, more patients developed new resistant organism growth in subsequent urine cultures in the group of patients that were not appropriately treated.
No values were found to be statistically significant.

Conclusion: 

• The educational intervention was not effective at guiding provider empiric antibiotic choice in the ED

• ASB was often treated in the pre- and post-intervention periods

• The expected practice document was not an effective tool in altering clinical behavior in the ED

Title:
Daptomycin Combination Therapy with Ceftaroline versus Anti-Staphylococcal Beta-Lactams for the Treatment of Persistent Methicillin-Resistant Staphylococcus aureus Bacteremia

Authors:
Christopher Staten, PharmD
Kelvin Gandhi, PharmD, BCIDP
Lindsey Moeller, PharmD, BCPS

Background:
Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is poorly defined and not well established; recent literature characterizes it as a bloodstream infection with ongoing positive blood cultures for two or more days despite receipt of targeted therapy against MRSA. Persistent bacteremia may occur in up to 39% of S. aureus bacteremia cases, and has been associated with increased mortality, risk of metastasis, and incidence of microbiologic relapse. Traditional pharmacotherapy includes either vancomycin or daptomycin, however when persistent MRSA bacteremia is present, synergistic therapy is oftentimes explored to assist in microbiological eradication. Combination therapies of beta-lactams with daptomycin are currently being clinically evaluated due to their theorized enhancement of daptomycin binding based on data from in vitro studies. Beta-lactam synergy with daptomycin may increase depolarization of the bacterial cell wall to improve daptomycin efficacy and bactericidal activity. Despite strong in vitro data, the in vivo data is inconsistent when demonstrating impact on clinical outcomes. Ceftaroline is most commonly utilized in clinical practice as the synergistic adjunctive agent of choice with daptomycin due to its strong in vitro data, however it is more costly compared to other studied adjunctive agents such as anti-staphylococcal beta-lactams (ASBL).

Methods: 
This was a retrospective multicenter cohort study that included hospitalized adult patients with at least one blood culture positive for MRSA from September 1, 2022 to October 31, 2025 at AdventHealth East Florida Division hospitals. Patients were allocated into two groups, either daptomycin plus ceftaroline (DPT/CFT), or daptomycin plus an ASBL (DPT/ASBL), which included cefazolin and oxacillin. Patients were included if they received 72 hours of combination therapy in either group. Excluded patients were those under 18 years of age, pregnant, or received less than 72 hours of combination therapy. The primary outcome was composite clinical failure; composed of 60-day mortality, 60-day recurrence, and persistent bacteremia at day five of combination therapy. A non-inferiority threshold was set at 10.0% based on incidence rates demonstrated by pertinent literature. A multivariate logistic regression was performed on the primary outcome to assess possible confounding variables.

Results: 
A total of 53 patients were investigated in this study, 41 in DPT/CFT and 12 in DPT/ASBL. The primary outcome of composite clinical failure was met in 13 (31.7%) in the DPT/CFT group and 3 (25.0%) patients in the DPT/ASBL group (ARD 6.71). The difference of 6.71% did reach the threshold set for non-inferiority of 10% difference. A multivariate logistic regression analysis showed no statistically significant associations identified for the primary outcome by ICU admission, Charlson Comorbidity Index (CCI), time to source control, and duration of combination therapy.

Discussion:
This retrospective analysis comparing daptomycin plus ceftaroline (DPT/CFT) to daptomycin plus ASBL (DPT/ASBL) for persistent MRSA bacteremia, demonstrated that DPT/ASBL was non-inferior to DPT/CFT. Of note, patients in the DPT/CFT arm were generally more critically ill; though not reflected in the differences in APACHE II score, CCI, or Pitt Bacteremia Score, they had more complicated sources of infection, higher ICU admission rates, and increased clinical instability, potentially impacting outcomes.

Conclusion: 
Nonetheless, our findings ultimately suggest that DPT/ASBL combination may be an alternative regimen to DPT/CFT in a select clinical context. This combination could provide an alternative option for persistent MRSA bacteremia, but prospective studies are needed to better define the comparative clinical efficacy and safety in different patient populations.

Oral Beta-lactam (BL) Versus Fluoroquinolone (FQ) or Sulfamethoxazole-Trimethoprim (SMXTMP) in Uncomplicated Gram-Negative Bacteremia (uGNB) Jared Robbins, Tyler Baumeister, Tracey Bastian Williamson Medical Center - Franklin, TN

Background/Purpose: Gram negative bacteremia is associated with significant morbidity and mortality. Historically, uncomplicated gram-negative bacteremia (uGNB) has been treated with highly bioavailable oral options like fluoroquinolones (FQ) or sulfamethoxazole/trimethoprim (SMX-TMP). This is primarily due to pharmacokinetic concerns and questionable bioavailability of other agents such as beta-lactam (BL) antibiotics. Therefore, optimal oral step-down agents for uGNB remains highly debated. The unfavorable safety profiles of FQs and SMX-TMP have sparked interest in investigating safer alternatives. Current literature including systematic reviews, meta-analyses, and cohort studies suggest beta-lactams may be an efficacious and safe alternative for uGNB. This study aims to compare the efficacy and safety of BLs versus FQs/SMX-TMP for oral step-down therapy in uGNB in a community hospital setting.

Methodology: This was a single-center, IRB-approved, retrospective study conducted at a 337- bed hospital in Franklin, Tennessee that evaluated clinical failure rates of 100 patients receiving either BLs or FQs/SMX-TMP for the treatment of uGNB. Eligible patients admitted between August 1, 2023, and August 1, 2025, who met inclusion and exclusion criteria were identified for analysis. Baseline characteristics included age, sex, weight, Charlson comorbidity score (CCS), and PITT bacteremia score. The primary outcome was a composite of clinical failure, defined by having 1 of the following; 30-day hospital readmission due to antibiotic intolerance, 30-day recurrent bacteremia caused by the same microorganism, or escalation in therapy. Secondary outcomes included individual components of the primary outcome at 90 days, 90-day incidence of Clostridioides difficile infection (CDI), duration of therapy (summative and breakdown components of IV/PO groups), and hospital length of stay. Safety outcomes included rates of hyponatremia, acute kidney injury, and hyperkalemia as primary cause of re-admission at 30 and 90 days, and a composite of these components.

Results: This trial included 100 total patients, 58 designated in the BL group, and 42 designated in the FQ/SMX-TMP group. Baseline characteristics were comparable between groups, with the exception of age (78.8 years vs 71.3 years, in the BL vs FQ/SMX-TMP groups, respectively; p=0.004) and CCS (5.2 vs 4.2, in the BL vs FQ/SMX-TMP groups, respectively; p=0.04). The primary outcome of 30-day composite clinical failure occurred in 4/58 patients (6.9%) in the BL group, and 4/42 patients (9.5%) in the FQ/SMX-TMP group. (RR 0.72; CI 0.19-2.73; p=0.72). For secondary outcomes, the 90-day clinical failure composite outcome occurred in 3/58 (5.2%) of patients in the BL group, and 4/42 (9.5%) in the FQ/SMX-TMP group. (RR 0.54; CI 0.13-2.3; p=0.449). Average length of stay, IV antimicrobial duration, and oral antimicrobial duration were similar between the two treatment groups. CDI did not occur in either treatment group. The 90-day composite safety outcomes occurred in 0/58 (0%) patients in the BL group, and 2/42 (4.8%) in the FQ/SMX-TMP group (RR 0.15; CI 0.007-3.02; p=0.174). Of the two events in the FQ/SMX-TMP group, both were due to hyponatremia leading to re-admission and occurred within 30 days post-discharge.

Background

A significant portion of hospitalized adults presenting to a hospital may require treatment with broad spectrum antibiotics. Cases involving suspected infections and sepsis are frequent occurrences in which empiric antibiotic use is warranted. Vancomycin and piperacillin/tazobactam (pip/tazo) comprise a widely used antibiotic regimen incorporating a glycopeptide antibiotic and a β-lactam/β-lactamase inhibitor respectively. This regimen provides broad-spectrum activity against Gram-positive, Gram-negative, and anaerobic pathogens including methicillin resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. The aim of this study is to determine the relationship between differing doses of pip/tazo and the incidence of AKI in patients treated with concomitant vancomycin and pip/tazo. By identifying whether higher doses of pip/tazo are associated with increased AKI rates, this research seeks to inform antimicrobial stewardship efforts and optimize patient safety while preserving therapeutic efficacy.

Methods

This retrospective cohort study was conducted to assess the impact of different piperacillin/tazobactam dosing regimens on the incidence of nephrotoxicity for patients receiving concomitant vancomycin therapy. The research site for this study is a 700-bed, not-for-profit, public hospital system in a rural Georgia. In March 2024, the site for this study changed protocol regarding piperacillin/tazobactam administration from 3.375gm to 4.5gm IV extended-infusion. Patients receiving concomitant vancomycin and piperacillin/tazobactam were split into 2 groups based on which piperacillin/tazobactam dosing regimen they received. The Institutional Review Board at the research site approvedwill review the methodology of this study for approval prior to any patient data collection.

Results - Vancomycin + Piperacillin/Tazobactam 3.375g ( n=105): 13 (12.4%) experienced AKI.
                Vancomycin +Piperacillin/Tazobactam 4.5g ( n=105) : 16 (15.2%) experienced AKI. 
                 p-value = 0.55


Conclusion - Currently, there is not evidence to suggest that the change in piperacillin/tazobactam extended infusion dosing at the primary site had an impact on nephrotoxic risk for patients being treated with concomitant VPT therapy.

Background/Purpose: 
Hepatic encephalopathy (HE) is a common and burdensome complication of cirrhosis, associated with significant morbidity, mortality, and frequent hospitalizations. Lactulose remains the cornerstone of therapy; however, its use is often limited by poor tolerability and adherence. Rifaximin is recommended as add-on therapy for prevention of recurrence, but in clinical practice, it is increasingly used as monotherapy, particularly in patients who are unable to tolerate lactulose. 

Despite this shift, there is limited real-world data evaluating the effectiveness of rifaximin monotherapy in the inpatient setting. The purpose of this study was to compare clinical outcomes between patients treated with rifaximin monotherapy and those treated with rifaximin in combination with lactulose for the treatment of overt HE across the Wellstar Health System. 
 
Methodology: 
Adult patients (≥18 years) with cirrhosis who had been hospitalized for an episode of overt hepatic encephalopathy (HE; ICD-10 K76.82) between January 1, 2015, and July 31, 2025, were enrolled into this retrospective cohort study. These patients were categorized according to the treatment they received while hospitalized: those treated with rifaximin as monotherapy, and those treated with rifaximin + lactulose. Patients with acute liver failure, active infection, intensive care unit admissions, or hospitalizations of < 24 hours were excluded. The primary outcome was improvement in hepatic encephalopathy, defined as a reduction of one or more points in the West Haven Score grade during hospitalization. Secondary outcome measures include changes in serum ammonia levels, length of stay (LOS), acute kidney injury (AKI) events, in-hospital mortality, 30-day mortality, and 30-day readmissions due to HE. The continuous data collected were compared using two-sample t-tests. Categorical data collected were compared using chi-squared analyses. A p-value of ≤ .05 was used to determine if observed differences are statistically significant. 
 
Results: 
A total of 104 patients were included, with 52 patients in each group. Baseline characteristics were well balanced between groups, including age (57.3 vs 56.8 years, p=0.84), Charlson Comorbidity Index (4.94 vs 4.79, p=0.48), and MELD score (~20 in both groups, p=0.91). 

Both treatment groups demonstrated meaningful reduction in WHS grade during hospitalization. The mean WHS decreased from 2.94 to 0.96 in the lactulose + rifaximin group and from 2.87 to 0.88 in the rifaximin monotherapy group. The degree of improvement was similar between groups (mean change: 1.98 vs 1.99, p=0.96).  

Ammonia levels decreased in both groups as well, from 75.7 to 53.9 µmol/L in the lactulose + rifaximin group and from 71.3 to 52.3 µmol/L in the rifaximin group, with no significant difference observed (p=0.61). 

Hospital length of stay was numerically shorter in the rifaximin monotherapy group (5.38 vs 6.85 days), though this did not reach statistical significance (p=0.17). 

Rates of AKI, 30-day readmission, and mortality were low and comparable between groups. AKI occurred in 3.8% vs 5.8% of patients (p=0.65), and 30-day readmission occurred in 0% vs 3.8% (p=0.15) in the lactulose + rifaximin and rifaximin groups, respectively. In-hospital mortality occurred in 0% of patients in the lactulose + rifaximin group and 5.8% in the rifaximin group; however, this difference was not statistically significant (p=0.08). 

Conclusions: 
Rifaximin monotherapy demonstrated similar effectiveness to combination therapy with lactulose in reducing WHS grade and reducing ammonia levels during hospitalization. 

No meaningful differences were observed in readmissions, AKI, or overall safety outcomes. While not statistically significant, the shorter LOS observed in the monotherapy group may suggest a potential advantage that warrants further investigation. 

These findings support the idea that rifaximin monotherapy may be a reasonable alternative in select patients, particularly those who are unable to tolerate lactulose. Given the limitations of retrospective data and potential confounding factors, larger prospective studies are needed to better define the role of rifaximin monotherapy in the management of hepatic encephalopathy. 

Title: Evaluation of Antibiotic Duration Between Concordant vs Discordant Multiplex Pneumonia PCR and Respiratory Culture Results 
Authors: Kala Eliacin, Rachel Tendler, Haodi Ruan  
Background/Purpose: Multiplex pneumonia PCR panels provide rapid identification of respiratory pathogens; however, discrepancies between PCR results and conventional respiratory cultures can introduce uncertainty in antimicrobial decision-making. The purpose of this study is to evaluate PCR-culture concordance vs discordance and their implications  on antibiotic duration in critically ill patients with suspected pneumonia.
Methodology: This was a single-center, retrospective chart review of adult patients admitted to the intensive care units at Emory Saint Joseph’s Hospital between January 1, 2023 and December 31, 2025 . Patients were included if they had suspected pneumonia and underwent both a multiplex pneumonia pathogen panel (PPP) and respiratory culture during the same hospitalization. Patients were excluded if they had a concurrent infection, died within 5 days of specimen collection, or had concordant negative PCR and culture results. The primary outcome was total duration of antibiotic therapy within 14 days of PPP and culture collection. Secondary outcomes included antibiotic regimens eligible for change, antibiotic regimens changed, ICU length of stay (LOS), hospital LOS, and pathogen identification. Continuous variables were reported using descriptive statistics and compared between groups using an unpaired t-test.
Results: A total of 70 patients were included, with 36 (51.4%) concordant results and 34 (48.6%) discordant results. Average age was around 62.3 years in the concordant group and 61.3 years in the discordant group and average weight was about 75 kg in both groups. Overall, the majority type of pneumonia identified in patients for both groups was community acquired pneumonia (CAP) with 41.7% in the concordant group and 47.1% in the discordant group. The mean total days of antimicrobial therapy within 14 days of index testing were 7.8 days in the concordant group compared with 8.0 days in the discordant group (p = 0.8303). ICU LOS was 13.8 days in the concordant group versus 13.2 days in the discordant group. Hospital LOS for the concordant and discordant group was 26.4 days versus 18.5 days, respectively. Antibiotic regimens were eligible for modification in 48 patients (68.6%), including 23 (63.9%) in the concordant group and 25 (73.5%) in the discordant group. Antibiotic regimens were changed in 37 patients (52.9%) overall following PPP results. Multiplex PCR detected more pathogens than respiratory culture, with common organisms including Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Overall, resistance genes were detected in 9.7% of cases with mecA/C being the most common in both the concordant group (13.5%) and discordant group (25.7%).
Conclusions: There was no difference in antibiotic duration of treatment or ICU LOS between concordant and discordant PPP and respiratory culture results. Hospital LOS, however, was shorter in the discordant group but may have been due to confounding factors. PPP results frequently identified opportunities for antimicrobial optimization, and antibiotic regimens were modified in over half of patients. These findings show that concordance vs discordance between multiplex PCR and culture results were not associated with a difference in antibiotic duration in critically ill patients with suspected pneumonia.

Title: Antimicrobial Prescribing Practices for Community-Acquired Pneumonia (CAP) in a Community, Teaching Health System
Authors: Anna Collins, Chris Whitman, Rachel L. Foster, Jeff Bruni, Cherie Abernathy
Background: Community-acquired pneumonia (CAP) is a major U.S. health concern, particularly in adults aged 65 years and older. Many antibiotic prescriptions may deviate from guidelines, with frequent overuse of broad-spectrum antibiotics, failure to de-escalate therapy, and prolonged durations of therapy. This project aims to evaluate prescribing patterns for the treatment of community-acquired pneumonia (CAP) within Infirmary Health (IH). Antibiotic selection and treatment durations were compared to current national guideline recommendations to determine guideline concordance and appropriateness of current inpatient CAP treatment within IH. These findings will support data-driven antimicrobial stewardship efforts by identifying specific areas for improvement in prescribing practices to enhance patient care and reduce antimicrobial resistance within the community.
Methods: This study is a retrospective chart review of adult inpatients who were diagnosed with and treated for CAP within IH in 2024. International Classification of Diseases (ICD-10) codes and Diagnosis Related Groups for CAP were used to obtain patients. Patients were then randomized and 270 patients were reviewed. The first admission in 2024 was included per patient. The primary outcome was to determine the prevalence of Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) guideline-concordant CAP treatment according to disease severity and risk factors. The primary outcome was assessed at three different timepoints: day one of CAP therapy, day two of CAP therapy, and the last day of inpatient CAP therapy. Secondary outcomes included comparing baseline characteristics, length of stay, 30-day readmission, and 30-day all-cause mortality between patients treated according to IDSA/ATS guidelines and those that were not. Patients were excluded if they received less than 72 hours of antibiotics for CAP treatment, had a concurrent infection requiring a longer length of therapy or alternative drug selection, any hospital-acquired or ventilator-associated pneumonia, had a diagnosis of cystic fibrosis or other advanced structural lung disease, had conditions predisposing to noncommunity-acquired pathogens, patients who left against medical advice, expired, or transitioned to hospice during the CAP treatment course, history of lung transplant, pregnant or breastfeeding, incarcerated, those transferring from an outside hospital, and patients with a pneumonia-related complication.
Results: There were 2,576 unique patients identified. Of these, 270 charts were reviewed and 130 patients were included in the final analysis. The median age was 71 and 68 years in the guideline concordant and discordant groups, respectively, and baseline characteristics were similar between the two groups. Recent healthcare exposure in the prior 90 days was more common among patients receiving guideline-discordant therapy: 19% had received intravenous (IV) antibiotics compared with 2% in the guideline-concordant group, and 29% had a hospital admission compared with 9%, respectively. Overall, 64% of patients received guideline discordant therapy. Rates of guideline discordance were similar across the three timepoints assessed. Notably, 36% of patients received empiric MRSA or Pseudomonas therapy when it was not indicated. The antibiotic lengths of therapy were 8 and 9 days in the guideline concordant and discordant groups, respectively. There were no significant differences in length of stay, 30-day readmission, or 30-day mortality between the two groups.
Conclusions: The majority of patients in this population received guideline discordant therapy for the treatment of CAP, with trends toward overly broad antibiotic selection and longer than recommended durations of therapy. Patients receiving guideline discordant therapy were more likely to have an admission and receipt of IV antibiotics in the prior 90 days. These findings highlight an opportunity to optimize antibiotic selection and duration of therapy for CAP treatment within Infirmary Health.

Title: 
Safety Outcomes of Empiric Linezolid versus Vancomycin in Patients with Pneumonia and Risk Factors for Methicillin-Resistant Staphylococcus aureus Infection

Purpose:
Vancomycin and linezolid are primary agents recommended for treating methicillin resistant Staphylococcus aureus pneumonia¹. However, linezolid tends to become the secondary agent during therapy selection due to lack of familiarity, cost, or concern for adverse effects of myelosuppression or serotonin syndrome. The purpose of this study is to investigate key safety outcomes in use of intravenous linezolid and vancomycin for the purpose of inpatient treatment of pneumonia.

Methods:
The study was conducted as a single-center, Institutional Review Board (IRB)-approved, retrospective observational cohort study. Patients were identified from clinical data already available in the Ascension central data repository (across 11 practice sites) and screened based on inclusion and exclusion criteria. Encounters were then categorized by receipt of either “vancomycin” or “linezolid,” with further stratification for the various primary and secondary outcomes. The primary outcome is defined as composite safety outcomes, defined as incidences of acute kidney injury, cytopenias, serotonin syndrome, infusion reactions, and suspected or confirmed Clostridioides difficile infection. This data was collected from the facilities’ respective electronic health records for patients admitted between January 1, 2020 to September 30, 2025. Data was analyzed using Student’s t-test or Wilcoxon rank sum test or Chi-square or Fisher’s exact test, as appropriate for the data type. Alpha was set as 0.05 with 80% power.

Results:
14 patients were included in the study from a single site of the 11 sites. The remaining sites are assessed in a separate analysis. 7 patients were in each of the two groups, vancomycin and linezolid. Baseline characteristics were similar between groups. There was no significant difference found between the composite safety outcomes in either treatment group. Within the secondary outcomes, vancomycin patients had a statistically significant increased rate of 30-day all-cause mortality when compared to those of the linezolid group.

Discussion:
In this study, we found no significant difference in composite safety outcomes between patients with pneumonia being treated with vancomycin or linezolid. This may represent comparable safety profiles between the agents. It is important to consider the increase in 30-day all-cause mortality rate and apply it to a patient’s full clinical picture. More research is warranted with a larger sample size.

Authors: Shannon R. Mayberry, Cristina Martinez, Benjamin Albrecht, Sujit Suchindran, Sarah B. Green  

Resident e-mail for contact: [email protected] 


Purpose/Background: 
Treatment of low-risk AmpC-inducible organisms should rely on antimicrobial susceptibility testing (AST) to guide treatment of infection. Current Infectious Diseases Society of America (IDSA) guidelines identify Serratia marcesens, Morganella morganii, and Providencia spp. as low-risk species. Per this guidance, when susceptibility to agents such as ceftriaxone and piperacillin-tazobactam is demonstrated, treatment with that antibiotic is considered appropriate. However, infections with high bacterial burden, including endocarditis and central nervous system (CNS) infections, pose an additional challenge for optimal treatment selection. The IDSA guidelines state cefepime may be reasonable to utilize for high-inoculum infections despite susceptibility to ceftriaxone, due to less risk of AmpC hydrolysis. However, efficacy to cefepime in this setting is uncertain given potential for an inoculum effect, while carbapenems appear less affected. Clinical evidence remains limited, and treatment guidance for high-inoculum AmpC infections is unclear. In this retrospective case series, we describe the clinical outcomes of patients treated with a carbapenem, cefepime, or an alternative beta-lactam agent for deep-seated endovascular and CNS infections due to low-risk AmpC-inducible organisms.  

Methods: 

This IRB approved, retrospective case series included adults (≥18 years) admitted to Emory Healthcare acute care hospitals between January 1, 2023, and January 31, 2025, with endocarditis, endovascular, or CNS infection due to a low-risk AmpC-inducible organism (Serratia marcescens, Morganella morganii, or Providencia spp.). Patients were identified through diagnosis codes (e.g. endocarditis, endovascular infection, CNS infection) and a positive blood or CNS culture for a low-risk AmpC organism. A total of 28 patients were identified for review. Further exclusion criteria were polymicrobial cultures, switch of therapy after 72 hours, or definitive non–β-lactam or combination therapy. Of this, 10 patients were included for final evaluation.  Case data collected included patient demographics, comorbidities, infection characteristics, microbiology, antimicrobial therapy, 30-day all-cause mortality, 90-day infection recurrence, 90-day readmission, and adverse events. 

Results: 

Ten patients with high-inoculum infections due to low-risk, high inoculum AmpC-inducible organisms were included. Nine infections were caused by Serratia marcescens and one by Morganella morganii. Infection types included endovascular infections (n=6), central nervous system infections (n=3), and infective endocarditis (n=1). Initial antimicrobial regimens varied and included ceftriaxone, cefepime, ceftazidime, and piperacillin/tazobactam, with several patients undergoing antibiotic escalation after organism identification. All but one patient had infectious diseases consultation. Antibiotic modifications were common, ranging from zero to eight changes during admission. One patient experienced inpatient mortality. A single patient had a 90-day infection-related readmission. No consistent signal of clinical failure was observed among patients treated with ceftriaxone compared with cefepime or carbapenems. Despite frequent antimicrobial adjustments, most patients achieved clinical stability without recurrent infection or excess mortality within 90 days. 

Conclusions:  

In this small retrospective case series, clinical outcomes were similar among patients receiving ceftriaxone, cefepime, or carbapenems for high-inoculum infections caused by low-risk AmpC-inducible organisms. Rates of inpatient mortality and 90-day readmission were low, and no clear outcome advantage was observed with broader-spectrum therapy. These findings suggest that carefully selected non-carbapenem β-lactams may be a reasonable option in certain deep-seated infections when supported by susceptibility data and close clinical monitoring. However, frequent antibiotic escalation highlights ongoing clinician concern regarding inducible resistance and the inoculum effect. Given the limited sample size and descriptive design, definitive comparative conclusions cannot be drawn. Larger, multicenter studies are needed to better define optimal therapy in this high-risk population. Until additional data are available, antimicrobial stewardship decisions should balance theoretical resistance risks with the goal of preserving carbapenem activity. 

Multidrug resistant organisms can be difficult to treat due to limited options and are a public health threat. Increasing rates of antimicrobial resistance have led to high rates of mortality and greater costs for the healthcare system. Isolates are labeled as carbapenem-resistant Enterobacteriaceae (CRE) if noted to have resistance to at least one carbapenem agent or produce a carbapenemase. There are multiple mechanisms of carbapenem resistance including carbapenemase production, porin channel mutations, and overexpression of efflux pumps. The literature suggests that the risk of carbapenemase production is less than 3% in isolates that are resistant to ertapenem but susceptible to meropenem and imipenem-cilastatin. A study by Wang et al showed that ertapenem-mono-resistant isolates were more likely to be susceptible or intermediate to beta-lactams and beta-lactam/beta-lactamase inhibitor combination agents when compared to meropenem and imipenem-cilastatin resistant isolates. However, current Infectious Diseases Society of America (IDSA) guidelines recommend that they be treated with extended infusion of meropenem or imipenem-cilastatin.  
The Clinical and Laboratory Standards Institute (CLSI) recently lowered the susceptibility breakpoint of ertapenem from a mean inhibitory concentration (MIC) of <2 to <0.5 µg/mL, increasing the number of isolates that would be labeled as CRE. The purpose of this study was to describe the outcomes in patients with ertapenem mono-resistant Enterobacteriaceae infections, and to compare the use of carbapenem and non-carbapenem antibiotics in ertapenem mono-resistant isolates.  
This study was a single-center, retrospective chart review of mono-resistant Enterobacterales isolates from January 1st, 2023 to December 31st, 2024. Mono-resistance is defined as having an ertapenem MIC of > 1 mg/L and meropenem MIC of < 1 mg/L. Patients were included if they were > 18 years old at time of culture collection, were inpatient, and completed an antibiotic course for an infection with a positive culture. At our institution, genotyping data was only available for some blood cultures. Patients were excluded from analysis if cultures were collected at an outside facility, belonged to protected population, and did not receive antibiotic treatment. The comparative groups were patients treated with carbapenems, non-carbapenem beta-lactams, and non-beta-lactam antibiotics. The primary outcome was clinical cure of infection. To strengthen our analysis of the primary outcome, an infectious diseases physician validated the primary outcome. Secondary outcomes included microbiological cure, in-house mortality, and inpatient length of stay. For statistical analysis, chi-square tests and student t-tests were conducted when appropriate.  
Ninety-eight isolates were reviewed: 25 (26%) were treated with a carbapenem, 51 (52%) were treated with a non-carbapenem beta-lactam, and 22 (22%) were treated with a non-beta-lactam. Most isolates came from a respiratory (34%) or urinary (20%) sample. Clinical cure rates were similar across three groups, 76% vs 80% vs 77%, respectively (p=0.8955). A multivariable regression analysis adjusted for sex, age, bed-type, polymicrobial culture status, and specimen type revealed no difference in clinical cure between antibiotic groups. When comparing carbapenem and non-carbapenem treated patients, the portion of patients who died was significantly smaller in the non-carbapenem group, (7 patients [28%] vs 4 patients [6%], p=0.006). Length of stay was longer in the carbapenem group when compared to the non-carbapenem group, but this difference was not statistically significant (76 days vs 32 days, p=0.184).  
Similar rates of clinical cure were observed in the three different groups (carbapenem, non-carbapenem beta-lactam, and non-beta lactam antibiotics), despite the current IDSA recommendation to use extended-infusion carbapenems for these mono-resistant isolates. Longer rates of length of stay in the carbapenem-treated group may cause a significant burden on our healthcare system. This suggests that most mono-resistant isolates are not carbapenemase producing and could be treated with beta-lactam therapy, if reported as susceptible.  

Title: Evaluation of Pediatric Pharmacy Driven Methicillin Resistant 
Staphylococcus Aureus (MRSA) Nasal Polymerase Chain Reaction (PCR) protocol 
Authors: Beth Addington, PharmD, BCPPS, Sarah Withers, PharmD, MS, BCIDP, Rachel Samples, PharmD, MBA 
Objective: To evaluate the impact of a pediatric pharmacy-driven MRSA nasal PCR protocol on the duration of anti-MRSA antibiotic therapy in pediatric patients before and after protocol implementation.
Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of pediatric infections. Current Infectious Diseases Society of America guidelines recommend MRSA nasal polymerase chain reaction (PCR) screening as a de-escalation tool for anti-MRSA therapy, given its high negative predictive value. While pharmacist involvement in antimicrobial stewardship has demonstrated benefits, limited data exist on pediatric pharmacy-driven MRSA nasal PCR protocols.
Methods: A single-center, pre- and post-interventional, retrospective cohort study included pediatric patients who received MRSA nasal PCR testing during two study periods: March 1–July 31, 2024 (pre-implementation) and March 1–July 31, 2025 (post-implementation). The primary outcome was the median duration of anti-MRSA antibiotic therapy before versus after protocol implementation. Secondary outcomes included pharmacist-ordered or documented MRSA PCRs, duration of intravenous antibiotic therapy, hospital length of stay, escalation of care, suspected or confirmed infection types, empiric and oral antibiotic selection, culture acquisition and results, and diagnostic performance of MRSA nasal PCRs, including sensitivity, specificity, positive predictive value, and negative predictive value.
Results: A total of 283 patients were included (pre-intervention n=134; post-intervention n=149). Median duration of intravenous anti-MRSA therapy was unchanged (1 [IQR 1–2] vs 1 [1–1] days; p=0.90). However, total MRSA antibiotic duration decreased (2 [1–6] vs 1 [1–5] days; p=0.01), as did total antibiotic duration (9 [7–14] vs 8 [6–12] days; p=0.02). Hospital length of stay was also reduced (median 3 vs 2 days; p<0.01). No significant differences were observed in culture acquisition, MRSA isolation rates, surgical interventions, or rates of therapy de-escalation. The MRSA PCR demonstrated high NPV (93.2% overall; 96.7% for pneumonia) but lower positive predictive value (PPV) (66.6% for SSTI; 20.0% for pneumonia).
Conclusion: Implementation of a pediatric pharmacy-driven MRSA nasal PCR protocol was associated with reductions in total MRSA and overall antibiotic duration, as well as shorter hospital length of stay, without adversely affecting clinical outcomes. These findings support the role of pharmacists in antimicrobial stewardship initiatives and highlight the clinical utility of MRSA PCR testing in pediatric populations.

BACKGROUND 
Linezolid is an oxazolidinone antibiotic with activity against drug-resistant gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus. The typical duration of linezolid therapy is approximately two weeks, with a maximum recommended duration of 28 days per the package insert. Bone and joint infections often require prolonged courses of antimicrobial therapy of 4 to 6 weeks. Linezolid is an ideal agent for treatment of bone and joint infections due to its reliable oral bioavailability and activity against resistant organisms. However, concerns regarding hematologic and neurologic toxicity often limit extended use beyond recommended durations. Real-world data describing tolerability during prolonged outpatient therapy remains limited. This study evaluated treatment completion and adverse effects associated with extended-duration linezolid therapy in an outpatient cohort. 
METHODS 
We conducted a retrospective cohort study at a large academic medical center evaluating adults prescribed oral linezolid 600 mg every 12 hours for more than 14 days for bone and joint infections between January 2022 and December 2024. Laboratory data were evaluated at two-week intervals. Patients lacking follow up laboratory data after the first 14 days of therapy or who were lost to follow up were excluded. Baseline demographics, laboratory values, duration of therapy, and adverse effects were collected from electronic health records. The primary outcome was the completion of prescribed therapy. Secondary outcomes included incidence of hematologic toxicity, defined as thrombocytopenia (platelet count < 150 x 103/ mcL or 50% decrease from baseline) or anemia (hemoglobin ≤ 10 g/dL or 2 g/dL decrease from baseline), and neurologic toxicity defined by documented new-onset neuropathic or visual symptoms. Time to adverse events was also assessed.