Resistant UTIs: When Can Cefepime–Enmetazobactam Help?

Why does pandemic-era antibiotic resistance matter for urinary infections?

The CDC reports that hospital-onset resistant infections and associated deaths increased by at least 15% between 2019 and 2020 across seven tracked pathogens. Longer hospital stays, greater use of invasive devices, staffing pressures, and disrupted prevention practices contributed to the problem. These are historical surveillance findings, rather than newly measured October figures, but they provide context for evaluating treatments for difficult bacterial infections. [CDC overview](https://www.cdc.gov/antimicrobial-resistance/data-research/threats/covid-19.html).

One such treatment is Exblifep, which combines cefepime with enmetazobactam. Its February 2024 FDA approval covers adults with complicated urinary tract infections, including pyelonephritis, an infection involving the kidneys, caused by specified susceptible bacteria. The approval provides an additional treatment option; it does not establish that every urinary infection requires this combination. [FDA approval and trial summary](https://www.fda.gov/drugs/drug-trials-snapshots/drug-trials-snapshots-exblifep).

What did the cefepime–enmetazobactam clinical trial actually show?

The randomized, double-blind ALLIUM trial enrolled 1,041 adults. In the primary efficacy population of 678 participants, 79.1% receiving cefepime–enmetazobactam achieved both clinical cure and the required reduction in urinary bacteria, compared with 58.9% receiving piperacillin–tazobactam. Clinical cure alone occurred in 92.5% and 88.9%, respectively. The distinction matters: the larger difference in the combined outcome reflected better bacterial clearance, rather than a comparably large improvement in symptoms. [FDA trial results](https://www.fda.gov/drugs/drug-trials-snapshots/drug-trials-snapshots-exblifep).

Published in JAMA in 2022, the study was funded by Allecra Therapeutics, whose role included study design and data analysis. Most participants in the primary analysis did not have bacteria producing extended-spectrum beta-lactamases, or ESBLs, limiting conclusions specifically about resistant infections. The trial also required intravenous treatment without switching to oral antibiotics. Because the comparator was piperacillin–tazobactam, the results do not establish superiority over carbapenem antibiotics such as meropenem. [ALLIUM trial publication](https://jamanetwork.com/journals/jama/fullarticle/2796946).

How does Exblifep overcome resistance, and what limits its use?

Cefepime kills susceptible bacteria by interfering with cell-wall construction. Some bacteria defend themselves using enzymes that break down antibiotics. Enmetazobactam blocks certain enzymes, including ESBLs, helping preserve cefepime's activity. Other resistance mechanisms remain effective: the prescribing information identifies bacteria producing KPC or metallo-beta-lactamases among those the combination does not cover. Culture and susceptibility results therefore help determine whether this particular drug can work. [FDA prescribing information](https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/216165s000lbl.Pdf).

Kidney function also influences prescribing because reduced clearance can increase drug exposure. Cefepime-associated neurological toxicity can include confusion and seizures, particularly when kidney impairment is accompanied by inadequate dose adjustment, although cases can occur despite adjustment. Other concerns include serious allergic reactions and Clostridioides difficile-associated diarrhea. The clinical decision must consider both the organism's susceptibility and the patient's ability to receive treatment safely. [FDA safety information](https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/216165s000lbl.Pdf).