Abstract
BACKGROUND: Despite being normal flora, and sometimes considered a contaminant, there are reports of Lactobacillus endovascular infections. However, large case series are lacking. We evaluated patient characteristics, antimicrobial susceptibility testing (AST), and all-cause mortality among patients with Lactobacillus bacteremia and/or endovascular infections managed in the Mass General Brigham (MGB) healthcare system. [Figure: see text] METHODS: The MGB Research Patient Data Registry and Massachusetts General Hospital microbiology database were queried to identify adults with blood, central line, or endovascular device culture(s) positive for Lactobacillus obtained at in-network hospitals between 1/1/00 and 9/1/22. Patient demographics, comorbidities, antibiotic regimens, 90- and 365-day all-cause mortality, and AST data for Lactobacillus isolates were extracted from charts when available. When echocardiography was available, potential endocarditis was classified according to the 2000 Duke criteria. Summary statistics were performed. [Figure: see text] RESULTS: We identified 333 patients with Lactobacillus bacteremia and/or endovascular infections. The mean age was 56 years, 42% (140/333) were female, and 36% (120/333) were immunocompromised (Table 1). Possible or definite endocarditis was identified in 19% (64/333), and 36% (121/333) had ≥1 additional organism(s) isolated in culture(s) growing Lactobacillus. The most common intended treatment duration was 1-2 weeks (91/209; 44%). Overall, 59/333 (18%) patients did not receive antibiotics active against Lactobacillus (Table 2). For patients with data available, all-cause mortality was 27% (85/316) at 90 days and 43% (130/301) at 365 days. For isolates with AST data, susceptibility to penicillin, ampicillin, and linezolid was reported for 96% (82/85), 99% (76/77), and 100% (66/66), respectively. Most isolates were resistant to meropenem (40/49; 82%) (Table 3). [Figure: see text] n reflects number of unique Lactobacillus isolates that were tested against each antimicrobial CONCLUSION: Among 333 patients with Lactobacillus bacteremia and/or endovascular infections, 1-year all-cause mortality was high. When Lactobacillus is isolated in blood cultures, clinicians should consider its relevance to the clinical scenario before labeling the organism as a contaminant. DISCLOSURES: Melis N. Anahtar, MD, PhD, Day Zero Diagnostics: Advisor/Consultant|Day Zero Diagnostics: Ownership Interest Elizabeth Hohmann, MD, Astra Zeneca: Grant/Research Support|Laguna Biotherapeutics: Grant/Research Support|MicrobiomeX/Tend: Grant/Research Support Sarah Turbett, MD, UpToDate: Author