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.

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

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