Cefmetazole or flomoxef linked to higher 14-day mortality vs carbapenems in ESBL-PE bacteremiaTrial Shows Carbapenems May Outperform Other Antibiotics for Bacteremia

Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy Published July 3, 2026 Study authors: Imai Haruka, Suzuki Jun, Mizuno Tomoki, Takahashi Shota, Itagaki Hideya, Akaba Tomohiro, Yoshida Mak… PubMed ↗ DOI ↗ Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

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Key Takeaway

Consider that cefmetazole or flomoxef may be associated with higher 14-day mortality than carbapenems in ESBL-PE bacteremia, but selection bias limits certainty.

This meta-analysis pooled data from 975 adults with extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE) bacteremia to compare outcomes with cefmetazole or flomoxef versus carbapenems. The primary outcomes were 14-day and 30-day mortality.

For 14-day mortality, the cefmetazole/flomoxef group had significantly higher odds compared with carbapenems (OR 2.32; 95% CI 1.24-4.35; I²=30%). In subgroup analyses, flomoxef was associated with increased 14-day mortality (OR 2.50; 95% CI 1.32-4.73), while cefmetazole was associated with decreased 30-day mortality versus carbapenems (OR 0.34; 95% CI 0.14-0.84). For 30-day mortality overall, no significant difference was observed (OR 1.12; 95% CI 0.71-1.75; I²=69%).

The authors note that cefmetazole results may have been influenced by treatment-selection bias, including lower baseline severity and more controllable infection foci. Adverse events and follow-up duration were not reported. The clinical impacts of cefmetazole and flomoxef varied by agent and context, so a unified effect cannot be determined. Clinicians should interpret these findings cautiously given the observational nature and potential confounding.

How this fits prior evidence

This meta-analysis extends prior evidence on carbapenem alternatives for resistant Gram-negative infections. Earlier coverage showed carbapenems linked to higher clinical failure in OXA-48-PE infections, suggesting alternative agents may be preferred. The current findings contrast by showing higher 14-day mortality with cefmetazole/flomoxef versus carbapenems in ESBL-PE bacteremia, though selection bias may confound results. It also adds to reports of high antibiotic resistance in Klebsiella pneumoniae from Burkina Faso and high meropenem resistance in Acinetobacter baumannii, highlighting the need for agent-specific evidence.

Researchers analyzed 975 adults with a specific type of serious blood infection called ESBL-PE bacteremia. They compared the effectiveness of two types of antibiotics: cefmetazole and flomoxef versus carbapenems. The goal was to see which treatment led to better survival rates over 14 and 30 days.

The results showed a significant difference in early outcomes. Patients treated with cefmetazole or flomoxef had significantly higher mortality rates at the 14-day mark compared to those who received carbapenems. However, by the 30-day mark, there was no significant difference in survival between the groups.

It is important to note that these results may be influenced by how patients were selected for treatment. Some researchers believe the data for cefmetazole might be affected by factors like lower initial illness severity. Because of these complexities and the specific nature of the infection, doctors must consider each patient's unique situation when choosing an antibiotic.

What this means for you:

Carbapenems showed better 14-day survival rates than flomoxef or cefmetazole in this specific blood infection study.

Common questions

How did the two types of antibiotics compare in this study?

The study found that patients treated with cefmetazole or flomoxef had significantly higher 14-day mortality rates compared to those who received carbapenems. However, at the 30-day mark, there was no significant difference in survival between the groups.

What specific infection was studied?

The study focused on adults with a specific type of blood infection called ESBL-PE bacteremia. This involves bacteria that produce certain enzymes making them harder to treat with standard antibiotics.

Are there reasons to be cautious about the results for cefmetazole?

Yes, the study notes that results for cefmetazole might have been influenced by treatment-selection bias. This means patients given cefmetazole may have had less severe symptoms or more manageable infections at the start.

Study Details

Study typeMeta analysis

Sample sizen = 975

EvidenceLevel 1

PublishedJul 2026

PMID42217670

View Original Abstract ↓

BACKGROUND: Cefmetazole and flomoxef are alternative therapies for extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE) bacteremia in Asia; however, their comparative efficacy remains unclear. We evaluated their efficacy versus carbapenems in adults with ESBL-PE bacteremia. METHODS: We conducted a systematic review and meta-analysis of targeted therapy for ESBL-PE bacteremia in adults. Primary outcomes were 14-day and 30-day mortality. Odds ratios (ORs) were pooled using fixed- and random-effects models. RESULTS: Ten studies (975 patients) were included. Fourteen-day mortality (5 studies) was significantly higher in the cefmetazole/flomoxef group than in the carbapenem group (fixed-effect OR: 2.32; 95% CI: 1.24-4.35; I = 30%), primarily driven by flomoxef in high-risk populations. Conversely, 30-day mortality (6 studies), largely reflecting cefmetazole use, showed no significant difference between groups (fixed-effect OR: 1.12; 95% CI: 0.71-1.75; I = 69%). Subgroup analyses revealed flomoxef was associated with increased 14-day mortality (OR: 2.50; 95% CI: 1.32-4.73), whereas cefmetazole was associated with decreased 30-day mortality (OR: 0.34; 95% CI: 0.14-0.84) versus carbapenems. However, cefmetazole results may have been influenced by treatment-selection bias, including lower baseline severity and more controllable infection foci. CONCLUSIONS: The clinical impacts of cefmetazole and flomoxef varied by agent and clinical context. Flomoxef was associated with increased 14-day mortality in high-risk populations, whereas overall 30-day mortality with cefmetazole did not differ significantly from carbapenems after accounting for clinical heterogeneity. Given this variability, a unified effect cannot be determined. Randomized controlled trials stratified by agent and disease severity are needed to evaluate their potential as carbapenem-sparing therapies.

Cefmetazole or flomoxef linked to higher 14-day mortality vs carbapenems in ESBL-PE bacteremiaTrial Shows Carbapenems May Outperform Other Antibiotics for Bacteremia

How this fits prior evidence

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Cefmetazole or flomoxef linked to higher 14-day mortality vs carbapenems in ESBL-PE bacteremiaTrial Shows Carbapenems May Outperform Other Antibiotics for Bacteremia

How this fits prior evidence

Common questions

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Study Details

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Clinical research that matters. Delivered to your inbox.

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