Epidemiology and treatment of endocarditis secondary to Enterobacterales other than Serratia spp

To investigate the epidemiology and outcomes of patients with non-Serratia Enterobacterales endocarditis.

Adult patients were identified at 14 hospitals between January 2000 and December 2024 with definite non-Serratia Enterobacterales endocarditis. Combination therapy was defined as receipt of ≥2 antimicrobial agents with documented in vitro activity against the primary pathogen for ≥72 hours. Clinical failure was defined as a composite of all-cause 42-day mortality or treatment-emergent resistance.

Seventy-five patients were included. The median (IQR) age was 67 (51-78) years, and 16% (12/75) were patients who inject drugs. The most common pathogens were E. coli [41% (31/75)] and Klebsiella spp. [37% (28/75)]. Klebsiella spp. were most commonly associated with septic emboli. Patients who experienced clinical failure were more likely to have a higher median (IQR) age [71 (66-79) versus 62 (43-76); P = 0.031], higher median (IQR) Charlson comorbidity index [4 (2-7) versus 3 (1-4); P = 0.026] and were less likely to receive surgery despite an indication [59% (10/17) versus 21% (10/47); P = 0.007]. After propensity score weighting, patients with valvular endocarditis treated with a combination regimen had a trend towards a lower 90-day mortality (HR = 0.39; 95% CI: 0.13-1.19; P = 0.098). However, patients who received combination therapy also had a proportionally higher rate of adverse events [33% (7/21) versus 13% (7/47); P = 0.054].

Use of combination treatment may improve mortality in patients with non-Serratia Enterobacterales endocarditis; however, larger studies are required. Adverse effects among patients who received combination therapy were common.