Epidemiological and molecular characterization of multidrug-resistant <i>Corynebacterium striatum</i> in a tertiary hospital in China

ABSTRACT Corynebacterium striatum has emerged as an important opportunistic nosocomial infection; however, epidemiological and antimicrobial resistance data from China remain limited. This study explored the epidemiological distribution, antimicrobial susceptibility profiles, resistance genes, virulence genes, plasmid characteristics, and phylogenetic relationships of clinical C. striatum isolates from a tertiary hospital in northern China. A retrospective study was conducted on C. striatum isolates recovered between February 2019 and December 2021 from patients with respiratory tract infections, urinary tract infections, catheter-related infections, or sterile-sites infections in which C. striatum was the sole pathogen. Antimicrobial susceptibility testing was performed using the E-test method according to CLSI M45 guidelines. Next-generation sequencing was performed for 14 clinical isolates, followed by hybrid assembly, resistance and virulence gene annotation using the CARD and VFDB databases, and single nucleotide polymorphism (SNP) phylogenetic analysis. Plasmid analysis was performed on four bloodstream isolates using Oxford Nanopore sequencing. A total of 312 clinical isolates were identified. All isolates were resistant to penicillin, meropenem, ceftriaxone, and ciprofloxacin but remained susceptible to vancomycin and linezolid. High resistance rates were also observed for tetracycline (69.87%), clindamycin (78.85%), gentamicin (44.23%), and erythromycin (79.17%). Genomic analysis identified 11 antimicrobial resistance genes, including the erm(X ) gene, which was detected in all clinical isolates. In addition, resistance plasmids were identified, suggesting a potential role in the dissemination of antibiotic resistance. Multidrug-resistant C. striatum is prevalent in this hospital setting. Continuous surveillance is warranted, and vancomycin and linezolid remain reliable therapeutic options. IMPORTANCE This study addresses a critical gap in the understanding of the emerging hospital pathogen Corynebacterium striatum in China. The findings demonstrate that multidrug-resistant strains are already widespread in the clinical setting, with nearly all isolates showing resistance to multiple first-line antibiotics. The identification of resistance genes on mobile plasmids is particularly significant, as it suggests the potential for rapid dissemination to other bacteria. These findings are important for increasing awareness among clinicians and hospitals regarding this underrecognized threat. They also underscore the need for routine testing for accurate identification of this bacterium, support the preferential use of vancomycin or linezolid for treatment, and provide evidence for strengthening infection control measures to prevent outbreaks.