Work

Emerging mastitis-associated Corynebacterium parakroppenstedtii and Corynebacterium pseudokroppenstedtii: clinical, microbiological, and epidemiological features from a two-year study in Guangdong, China

Year: 2026

Type: article

Abstract: Background Corynebacterium parakroppenstedtii , and C . pseudokroppenstedtii are emerging as significant pathogens in mastitis. Despite its clinical significance, data on its epidemiological, microbiological, and clinical features remain limited. Methods We conducted a comprehensive study on mastitis cases associated with Corynebacterium kroppenstedtii complex (CKC) in Guangdong, China (September 2021–September 2023). A total of 101 bacterial isolates were collected and initially identified as CKC using MALDI-TOF MS. Species-level confirmation was achieved through partial sequencing of the 16S rRNA, ropB , and fusA genes. Unclassified isolates were further characterized by whole genome sequencing (WGS). Clinical information was collected, and antimicrobial susceptibility testing was performed. Results Among the 101cases, C . parakroppenstedtii accounted for 86% of infections, while C . pseudokroppenstedtii for 12%, and a potential novel species for the remaining 2%. Notably, no C . kroppenstedtii infections were detected. Granulomatous lobular mastitis (GLM) was the predominant presentation, occurring in 72% of all cases. Comparative analysis revealed that C . pseudokroppenstedtii infections were associated with higher rates of pus formation and recurrence, whereas C . parakroppenstedtii infections were more prevalent among parous women. Moreover, C . pseudokroppenstedtii exhibited higher resistance rates to ceftriaxone (32.15% vs. 20.00%) and ciprofloxacin (75.00% vs. 19.09%) compared with C . parakroppenstedtii . Conclusions These findings challenge the prevailing understanding that C . kroppenstedtii is the main pathogen in mastitis and underscore the need for species-level identification to guide diagnosis and optimize antibiotic therapy for CKC-related mastitis. These insights are vital for improving clinical management and informing treatment strategies.

Source: Frontiers in Cellular and Infection Microbiology

DOI: 10.3389/fcimb.2025.1723551