It may not be necessary to administer IV antibiotics before beginning oral therapy for acute pyelonephritis, according to a presentation at the Critical Care Congress 2026 by pharmacists at the Charleston Area Medical Center (CAMC), in West Virginia.

“The findings challenge current Infectious Diseases Society of America [IDSA] guidelines, which recommend IV antibiotics in certain cases, particularly when fluoroquinolone resistance is high. These results highlight the need for further research to better define which patient populations, if any, may benefit from IV antibiotics, and support a more personalized treatment approach,” said Dellani Fix, PharmD, a PGY-2 critical care pharmacy resident at CAMC.

The IDSA generally recommends an initial dose of an IV antibiotic before switching to oral therapy when treating pyelonephritis, Dr. Fix noted.

Similar Results With IV, Oral Abx

Researchers analyzed 4,398 emergency department (ED) charts from January 2022 to June 2023, comprising adult patients with acute pyelonephritis identified by ICD-10 code or clinical criteria (urine culture ≥100,000 colony-forming units [CFUs]/mL or white blood cells >10,000 cells/mcL plus two symptoms). Pregnancy, catheter placement, urinary obstruction, renal transplants, antibiotic use within seven days, and an immunocompromised status were all exclusion criteria.

The final analysis included 179 patients with acute pyelonephritis, with the primary outcome the proportion of ED revisits within 14 days of discharge. These revisits sometimes led to a new hospital admission.

Of the 179 patients, 79 received IV antibiotics; the remainder received oral therapy. ED revisits were more frequent in the IV group (15.2%) than the non-IV group (10%; P=0.29).

Admissions (2.5% vs. 1%) and urinary tract infections (8.9% vs. 6%) were also more frequent in the IV group. There were no significant differences by antibiotic class or sex.

Dr. Fix acknowledged the study’s limited generalizability, as it comes from just one institution, and called for large randomized controlled trials to test the premise that IV antibiotics could be dispensable when treating acute pyelonephritis.

“Ultimately, this study advocates optimizing antibiotic stewardship and reconsidering the routine use of IV antibiotics in outpatient management of pyelonephritis,” Dr. Fix and colleagues said.

Dr. Fix reported no relevant financial disclosures.