Eggerthella lenta Bloodstream Infections: Increased Mortality Risk With Piperacillin-Tazobactam

Intravenous fluid drip, IV
Intravenous fluid drip, IV
Eggerthella lenta displays high minimal inhibitory concentrations to piperacillin-tazobactam (TZP), and empiric TZP monotherapy is a risk factor for 30-day mortality.

According to the results of a recent study published in Clinical Infectious Diseases, bloodstream infections with the anaerobic Eggerthella lenta were primarily shown to be from gastrointestinal sources, and increased 30-day mortality among patients with E lenta bloodstream infections was associated with empiric piperacillin-tazobactam (TZP) monotherapy.

In this retrospective population-based analysis of an Alberta, Canada, database, 107 cases of confirmed E lenta infections that occurred between 2009 and 2015 were evaluated. Antimicrobial susceptibility was reported for most cases with minimum inhibitory concentration (MIC) gradient strips. The appropriateness of antibiotic therapy was categorized on the basis of MIC breakpoints published by the European Committee on Antimicrobial Susceptibility Testing and the Clinical and Laboratory Standards Institute. Factors associated with 30-day mortality were assessed.

Of the 107 E lenta cases, 95 (89%) were bloodstream infections and 11 (10%) were skin and soft tissue infections. In addition, the researchers reported 1 intra-abdominal abscess infection. In 40% of cases, polymicrobial infections were identified.

The majority of isolates (72%) were from a gastrointestinal source, with 33% of cases attributed to appendicitis. Of those cases caused by appendicitis, 61.5% were associated with perforated appendicitis.

The mortality rate for patients with E lenta bloodstream infections within 30 days was 23%. The odds of mortality increased with empiric TZP monotherapy use (odds ratio, 4.4; P =.02) and intensive care unit stay (odds ratio, 6.2; P =.01).

The MICs for TZP for inhibition of 50% and 90% of bacteria were 32 and 64 μg/mL, respectively. The appropriateness of TZP monotherapy was associated with 30-day mortality based on TZP MIC breakpoints from the European Committee on Antimicrobial Susceptibility Testing (P =.01) and Clinical and Laboratory Standards Institute 2018 (P =.01) performance standards, but not for the Clinical and Laboratory Standards Institute 2011 standards (P =.19).

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The study authors concluded that “our analysis indicates that high TZP MIC’s are associated with significantly increased mortality with TZP monotherapy for empiric management of E lenta [bloodstream infections] and reflects the importance of appropriate empiric antimicrobial treatment guidelines and MIC breakpoints for anaerobes.”


Ugarte-Torres A, Gillrie MR, Griener TP, Church DL. Eggerthella lenta bloodstream infections are associated with increased mortality following empiric piperacillin-tazobactam (TZP) monotherapy: A population-based cohort study [published online January 24, 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy057