New Microbes and New Infections · Published 2026-07-30 · DOI 10.1016/j.nmni.2026.101821
Sao Yoshinaga, Masahiro Watanabe, Hiroshi Ito, Shinji Hatakeyama, Yoshiharu Saitou, Ryuya Yamamura, Naoaki Hashimoto, Toru Nanmoku, Kiyofumi Ohkusu, Hiromichi Suzuki
Objectives: Clostridium butyricum is an anaerobic gram-positive bacillus widely used as a probiotic preparation in Japan. Although generally considered safe, C. butyricum has rarely been isolated from blood cultures, particularly in immunocompromised or medically complex patients. We aimed to describe the clinical characteristics, microbiological findings, treatment, and outcomes of patients with C. butyricum isolated from blood cultures at a single academic hospital and to summarize published cases. Methods: We retrospectively reviewed 16 patients with C. butyricum isolated from blood cultures at University of Tsukuba Hospital between 2015 and 2025. Clinical characteristics, microbiological findings, antimicrobial treatment, and outcomes were evaluated. Preserved institutional isolates were identified using mass spectrometry and polymerase chain reaction–based ribotyping. We also summarized 31 published cases descriptively. Results: Sixteen institutional cases were identified. The most common clinical characteristic was central venous catheter use (75.0%). In many cases, C. butyricum was isolated from a single anaerobic blood culture bottle. All preserved institutional isolates were confirmed as C. butyricum and showed type B ribotyping patterns; however, strain-level attribution was not possible. All patients received β-lactam antibiotics, and three patients (18.8%) died. The 31 published cases were heterogeneous in age, clinical context, and microbiological identification methods. Conclusions: C. butyricum is rarely isolated from blood cultures but may warrant clinical assessment in medically complex patients. A possible association with probiotic exposure requires further investigation using genomic methods.
Abstract from DOAJ. Public domain (CC0 1.0).
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Yoshinaga, S., Watanabe, M., Ito, H., et al. (2026). Clinical analysis of 16 patients with Clostridium butyricum isolated from blood cultures: A 10-year single-center case series and review of published cases. New Microbes and New Infections. https://doi.org/10.1016/j.nmni.2026.101821