Commonly prescribed durations of therapy for many, if not most, bacterial infections are not evidence-based. Misunderstandings by clinicians and patients alike influence perspectives on antibiotic use, including duration of therapy and its role in antibiotic resistance. To demonstrate that shorter durations of antibiotic therapy are as efficacious as longer durations for many infections, a systematic review was undertaken of English-language articles by using PubMed to identify articles for inclusion. Additionally, infection-specific guidelines were identified for review of recommendations. Search terms included specific infection types, randomized controlled trial (RCT), duration of therapy, treatment duration, short course, and long course. Only RCTs of single-agent antibiotic therapy for the treatment of bacterial infections in adults were included. Independent data extraction of articles was conducted by two authors by using predefined guidance for article inclusion. In total, 23 RCTs met our criteria for inclusion. All trials compared single-agent antibiotics for a short and long antibiotic course in six common infections: community-acquired pneumonia, ventilator-associated pneumonia, intraabdominal infections, skin and soft tissue infections, uncomplicated cystitis, and complicated cystitis or pyelonephritis. Clinicians can decrease net antibiotic use by recommending shorter courses where evidence supports them. Antimicrobial stewardship programs that systematically address treatment duration may significantly affect institutional antibiotic use without negatively affecting patient care.

Meropenem‐vaborbactam is a new β‐lactam/β‐lactamase inhibitor combination designed to target Klebsiella pneumoniae carbapenemase (KPC)‐producing Enterobacteriaceae. Meropenem‐vaborbactam was United States Food and Drug Administration–approved for complicated urinary tract infections in patients 18 years of age or older. An understanding of the pharmacokinetics of meropenem when given in combination with vaborbactam is important to understanding the dosing of meropenem‐vaborbactam. In addition, the safety and efficacy of meropenem‐vaborbactam in a pediatric patient have yet to be described in the literature. The authors conducted a retrospective single‐patient chart review for a 4‐year‐old male patient with short bowel syndrome, colostomy and gastrojejunal tube, bronchopulmonary dysplasia, and a central line for chronic total parenteral nutrition and hydration management, complicated with multiple central line–associated bloodstream infections (BSIs). The patient was brought to our medical center with fever concerning for a BSI. On day 2, the patient was started on meropenem‐vaborbactam at a dosage of 40 mg/kg every 6 hours infused over 3 hours for KPC‐producing K. pneumoniae BSI. Meropenem serum concentrations obtained on day 5 of meropenem‐vaborbactam therapy, immediately following the completion of the infusion and 1 hour after the infusion, were 51.3 and 13.6 μg/ml, respectively. Serum concentrations correlated to a volume of distribution of 0.59 L/kg and a clearance of 13.1 ml/min/kg. Repeat blood cultures remained negative, and meropenem‐vaborbactam was continued for a total of 14 days. A meropenem‐vaborbactam regimen of 40 mg/kg every 6 hours given over 3 hours was successful in providing a target attainment of 100% for meropenem serum concentrations above the minimum inhibitory concentration for at least 40% of the dosing interval and was associated with successful bacteremia clearance in a pediatric patient.

A 22-year-old woman with cystic fibrosis developed QTc interval prolongation following lung transplantation in the setting of voriconazole therapy. After the discontinuation of voriconazole and initiation of isavuconazole, her QTc interval normalized. This case highlights the unique property of QTc interval shortening by isavuconazole among the triazole antifungals.

OBJECTIVES To describe the pharmacokinetics of levofloxacin in an obese adolescent patient in the pediatric intensive care unit. METHODS A single-patient medical record review was conducted. RESULTS A 168-kg, 15-year-old female with past medical history of Prader-Willi syndrome and asthma initially presented with respiratory distress secondary to asthma exacerbation. She failed non-invasive ventilation and was subsequently intubated for respiratory failure and progressed to high-frequency oscillatory ventilation. On hospital day 1 )HD 1( an infectious workup was begun because of a fever, worsening clinical status, and initiation of vasopressors and an empiric antimicrobial regimen of cefepime and clindamycin. The urine culture subsequently grew Escherichia coli and the respiratory culture grew Pseudomonas aeruginosa. She continued to be febrile, which was thought to be due to an intra-abdominal abscess. On HD 14, the antimicrobial regimen was changed to levofloxacin because of continued fevers and no significant clinical improvement. Levofloxacin was initiated at 1000 mg IV every 24 hours. Levofloxacin serum levels were obtained at 0.5, 3.5, and 11.5 hours after infusion, which were 8.61, 5.76, and 2.7 mg/L, respectively. These concentrations translated into a peak level of 8.79 mg/L, a half-life of 6.4 hours, and an AUC of 80 mg·hr/L, which are discordant from the expected peak of 16 mg/L, a half-life of 8 hours, and an AUC of 120 mg·hr/L. Based on these values, the levofloxacin regimen was adjusted to 1000 mg IV every 12 hours, and repeat levels 0.5, 3.5, and 11.5 hours after infusion were 9.91, 6.56, and 3.27 mg/L, respectively, corresponding to a peak of 10.5 mg/L, a half-life of 5.18 hours, and an AUC of 200 mg·hr/L. After the adjustment in levofloxacin regimen, she became afebrile, WBC resolution and improvement in her overall clinical status, and she received a total duration for levofloxacin of 21 days. CONCLUSION A levofloxacin regimen of 1000 mg IV every 12 hours was successful in providing for an appropriate AUC exposure and was associated with a successful clinical outcome in this morbidly obese adolescent.

Background The incidence of organisms with extended-spectrum beta-lactamases (ESBLs) is increasing. The data for using cefepime in ESBL-producing Enterobacterales infections is conflicting. More favorable outcomes are likely if minimum inhibitory concentrations (MICs) < 2 mcg/mL. The aim of this study is to compare the efficacy of cefepime versus carbapenems for ESBL-producing, non-bloodstream Enterobacterales infections. Methods This study was a single-center retrospective cohort study of patients who received cefepime or a carbapenem for at least 72 hours for the definitive treatment of an ESBL-producing Enterobacterales non-bloodstream infection between Jan. 1, 2011 and Sept. 30, 2021. ESBL production was identified if the isolate either had a positive confirmatory ESBL test from VITEK 2 (bioMérieux) or phenotypic resistance to ceftriaxone. Isolates had to have a MIC < 2 mcg/mL to cefepime or be susceptible to carbapenems. Isolates with a cefepime MIC 4-8 mcg/mL were not included due to likely higher rates of treatment failure. The primary endpoint was clinical failure, defined as persistence of symptoms requiring escalation of therapy or death. Descriptive statistics were used to compare groups. A univariate analysis and odds ratio was calculated for clinical outcomes. Results One hundred patients were included. Twenty-two patients received cefepime and 78 received a carbapenem. Table 1 describes patient characteristics and clinical outcomes. Most patients had a urinary tract infection (UTI) (94%). More patients receiving cefepime were admitted to the intensive care unit (40.9% versus 15.4%). Treatment with cefepime displayed higher rates of clinical failure when compared to treatment with carbapenems (13.6% versus 6.4%). Cohen’s d-test for clinical failure was 0.46, indicating a medium effect. Conclusion Based on our analysis, cefepime may have higher rates of clinical failure when compared to carbapenem treatment for ESBL-producing Enterobacterales. Most of our patients were treated for UTIs and the sample size for both arms were limited, particularly for the cefepime arm. Further research is needed to confirm the role of cefepime as a carbapenem-sparing option in the treatment of these drug-resistant infections. Disclosures Madeline King, PharmD, Shionogi: Honoraria|Tetraphase: speakers' bureau.