# P-1309. Comparative Treatment Outcomes of Non-Extended-Spectrum Beta-Lactamase (ESBL), Ceftriaxone Non-Susceptible, Enterobacterales Bacteremia with Piperacillin/Tazobactam, Cefepime, Carbapenem or Other Antibiotic Treatment

## TL;DR

This study compares treatment outcomes for a specific type of antibiotic-resistant bacterial infection and finds no significant difference between carbapenem and other antibiotics.

## Contribution

The study provides insights into optimal treatment for non-ESBL, ceftriaxone-resistant Enterobacterales bacteremia, an understudied infection subset.

## Key findings

- No significant difference in 30-day mortality between carbapenem and non-carbapenem treatments.
- Most common infection source was genitourinary, and most patients were elderly females.
- Collaboration with other systems is suggested to increase sample size for future studies.

## Abstract

Treatment of ceftriaxone-resistant Enterobacterales is largely focused on ESBLs, with a carbapenem being the preferred treatment. A subset of ceftriaxone resistant Enterobacterales are non-ESBLs. These organisms test negative for both genotypic and phenotypic detection of ESBLs. There is a paucity of data surrounding optimal management of this unique infection.

This retrospective observational chart review evaluated adult patients admitted between January 2016 and November 2024 with a bacteremia caused by a non-ESBL, ceftriaxone-resistant, piperacillin/tazobactam (TZP)-sensitive, cefepime (FEP)-sensitive Escherichia coli, Klebsiella oxytoca, Proteus mirabilis, or Klebsiella pneumoniae. Exclusion criteria included bacteremias caused by the same organism within 6 months prior to the index blood culture, polymicrobial bacteremia, treatment without intent to cure, carbapenem resistance, antibiotics with Gram-negative bacterial coverage for another indication, pregnancy or lactation, or patients who expired within 48 hours of positive cultures. Patients were stratified into 3 groups depending on the administered targeted treatment (FEP or TZP vs. carbapenem vs. other).

Of the 76 patients who were screened, 44 met the inclusion criteria. Four patients received a resistant cephalosporin for targeted treatment and were excluded from the analysis. There were 28 patients in the FEP or TZP group, 8 patients in the carbapenem group, and 4 patients in the other antibiotics group. The median age of the cohort was 77 years, most patients were female, and 30% of patients were in septic shock. The most common source of infection was genitourinary (63%). Thirty-day mortality was 3.8% in the FEP or TZP group, 14.3% in the carbapenem group, and 0% in the other antibiotic group (p=0.611). There was no significant difference in any of the secondary outcomes.

In this retrospective chart review study, there was no difference between carbapenem and non-carbapenem treatment for ceftriaxone-resistant, non-ESBL Enterobacterales bacteremia. Collaboration with other healthcare systems to increase sample size may help assess optimal treatment of these organisms.

All Authors: No reported disclosures