Comment on: ‘Epidemiology and treatment of endocarditis secondary to Enterobacterales other than Serratia spp ’

Dear Editor, We read with great interest the paper by Hausberger et al.1 a retrospective study describing 75 patients with infective endocarditis caused by Enterobacterales other than Serratia spp. This article addresses an open issue for which very limited evidence is currently available. However, we believe that the study’s findings do not adequately support the conclusions advanced by the authors. Although they acknowledge that larger studies are needed, the authors suggest in the conclusions of the abstract and in the final part of the discussion that their results would suggest that combination therapy may improve mortality. However, the difference in mortality between patients treated with monotherapy and those receiving combination therapies is not statistically significant. It is possible that the limited sample size compromised the ability to detect potential differences between the groups; nevertheless, in our view, this does not justify over-interpreting the apparent trend towards reduced mortality with combination therapy. Moreover, the authors allude to therapeutic success associated with the combination regimen including aminoglycosides (administered with a β-lactam for an average duration of 14 days). However, the clinical failure among the nine patients treated with the aminoglycoside-based combination regimen was 22% [2/9 patients; see Supplementary Materials], comparable to the overall clinical failure rate (24%) and with that of the monotherapy group (26%), with no statistical analysis provided to support this assumption.