Clinical characteristics and microbiota analysis of 44 patients with granulomatous mastitis.

Introduction: Granulomatous mastitis (GM) is a chronic inflammatory breast disease. In recent years, the role of in GM onset has received more and more attention. This study aims to detect the dominant bacterium in GM patients and analyze the association between clinical characteristics and infectious factors.

Methods: In this study, 88 samples from 44 GM patients, six acute lactation mastitis (ALM) patients, and 25 non-inflammatory breast disease (NIB) patients were divided into a GM pus group, a GM tissue group, an ALM pus group, and a NIB tissue group; then, 16S ribosomal DNA sequencing was used to explore their microbiota. The clinical data of all 44 GM patients were also retrospectively collected and analyzed to determine their relationship with infection.

Results: The median age of the 44 GM patients was 33 years, and 88.6% of patients had primary-onset cases, while 11.4% were recurrences; additionally, 89.5% of patients were postpartum and 10.5% were nulliparous. The serum prolactin level was abnormal in nine patients (24.3%). Samples from 15 GM patients (34.1%) had a abundance of >1% (1.08-80.08%), with eight (53.3%) displaying an abundance of >10%. was the only genus with significant differences between the GM pus group and the other three groups ( < 0.05). was the predominant species. Among clinical characteristics, a statistical difference in breast abscess formation was observed according to abundance in -positive and- negative patients ( < 0.05).

Discussion: This study explored the relationship between infection and GM, compared the clinical characteristics between -positive and- negative patients, and provided support for the role of species-in particular, -in the pathogenesis of GM. The detection of can predict GM onset, especially in patients with high prolactin levels or a history of recent lactation.