Clinical and microbiological characteristics of granulomatous mastitis caused by Corynebacterium species: a case series

Toshinori Hara; Hiroki Kitagawa; Kayoko Tadera; Rie Nagaoka; Yumiko Koba; Seiya Kashiyama; Yuta Kuhara; Takuji Omoto; Toshihito Nomura; Keitaro Omori; Norifumi Shigemoto; Sho Mokuda; Hiroki Ohge

doi:10.1016/j.jiac.2025.102605

Clinical and microbiological characteristics of granulomatous mastitis caused by Corynebacterium species: a case series

J Infect Chemother. 2025 Jan 3:102605. doi: 10.1016/j.jiac.2025.102605. Online ahead of print.

Authors

Affiliations

¹ Section of Clinical Laboratory, Division of Clinical Support, Hiroshima University Hospital, Hiroshima, 734-8551, Japan; Division of Laboratory Medicine, Hiroshima University Hospital, Hiroshima, 734-8551, Japan.
² Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, 734-8551, Japan; Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, 734-8551, Japan. Electronic address: hkitaga@hiroshima-u.ac.jp.
³ Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, 734-8551, Japan; Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, 734-8551, Japan.
⁴ Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, 734-8551, Japan.
⁵ Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, 734-8551, Japan; Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, 734-8551, Japan; Translational Research Center, Hiroshima University, Hiroshima, 734-8551, Japan.
⁶ Division of Laboratory Medicine, Hiroshima University Hospital, Hiroshima, 734-8551, Japan.

PMID: 39756677
DOI: 10.1016/j.jiac.2025.102605

Abstract

Corynebacterium species are an important cause of granulomatous mastitis (GM). Although there have been worldwide reports of infections caused by Corynebacterium kroppenstedtii, few cases of C. tuberculostearicum GM have been reported. We conducted a retrospective study to investigate the clinical and microbiological characteristics of GM caused by Corynebacterium spp. between January 1, 2014, and May 31, 2024. During the study period, six patients with GM were identified, including four cases of C. kroppenstedtii GM and two cases of C. tuberculostearicum GM. All patients were female with a median age of 32 years (range: 18-50 years). All patients underwent surgical drainage and were treated with clarithromycin. The minimum inhibitory concentration (MIC) values for various antimicrobial agents, including azithromycin, clarithromycin, ciprofloxacin, clindamycin, and trimethoprim-sulfamethoxazole, were higher for C. tuberculostearicum than for C. kroppenstedtii. Additionally, MALDI-TOF MS and 16s rRNA gene sequencing accurately identified C. kroppenstedtii and C. tuberculostearicum. Accurate identification of lipophilic Corynebacterium spp. is important for antibiotic treatment selection. If clinicians suspect lipophilic Corynebacterium spp. infection, particularly GM, they should ask the microbiology laboratory to test for lipophilic Corynebacterium spp.

Keywords: 16s rRNA sequencing; Corynebacterium; MALDI-TOF MS; granulomatous mastitis.

Copyright © 2025 Japanese Society of Chemotherapy, Japanese Association for Infectious Diseases, and Japanese Society for Infection Prevention and Control. Published by Elsevier Ltd. All rights reserved.