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Background <p><i>Corynebacterium striatum</i> is an opportunistic pathogen associated with a wide range of hospital-acquired infections, in which biofilm production plays a critical role in nosocomial transmission and pathogenicity. Although genotypic heterogeneity among <i>C. striatum</i> clinical isolates has been increasingly recognized, factors influencing isolate-specific biofilm formation, particularly host-derived factors, remain poorly understood. This study investigated the biofilm formation characteristics of <i>C. striatum</i> isolates with distinct genotypic and phenotypic profiles under exposure to human plasma proteins.</p> Methods <p>Sixty clinical <i>C. striatum</i> isolates were collected from inpatients at the Affiliated Hospital of Inner Mongolia Medical University between December 2013 and August 2022. The isolates, subcultured onto blood agar plates and the single colonies, were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antimicrobial susceptibility testing was conducted using the microbroth dilution method. Whole-genome sequencing was performed to assess genetic relatedness and to identify virulence and antibiotic resistance genes. Biofilm formation was evaluated using Congo red agar and crystal violet assays in the presence or absence of fibronectin or fibrinogen.</p> Results <p>Phylogenomic analysis classified the 60 <i>C. striatum</i> isolates into five evolutionary clades (I–V), with Clade I as the dominant lineage (45%, 27/60). Biofilm assays showed that 95% (57/60) of <i>C. striatum</i> isolates were biofilm producers, of which 56.14% (32/57) were moderate or strong producers. Notably, 92.59% (25/27) of Clade I isolates exhibited moderate or strong biofilm formation. Multidrug resistance was observed in 95% (57/60) of isolates, with high resistance rates to ciprofloxacin, cefepime, and ceftriaxone. Virulence gene distribution varied significantly across clades, with <i>spaDEF</i> (96.30%) and <i>whiB3</i> (100%) being highly prevalent in Clade I. Proteinase K showed the strongest biofilm-degrading activity. Exposure to fibronectin or fibrinogen (50&#xa0;µg/mL) enhanced biofilm formation in 47.37% (27/57) of isolates, whereas biofilm density decreased significantly in most strong biofilm-producing Clade I isolates.</p> Conclusions <p>This study reveals significant genomic heterogeneity among <i>C. striatum</i> clinical isolates and their association with biofilm formation. Importantly, it demonstrates isolate- and genotype-dependent effects of human plasma proteins on <i>C. striatum</i> biofilm production, highlighting the potential roles of <i>spaDEF</i> and <i>whiB3</i> in pathogenicity.</p>

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Phenotypic-genotypic characteristics of Corynebacterium striatum clinical isolates and diversified biofilm production capabilities in the presence of plasma proteins

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月6日

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  • Jiajia Su,
  • Juan Wen,
  • Wenqi Zheng,
  • Junrui Wang

摘要

Background

Corynebacterium striatum is an opportunistic pathogen associated with a wide range of hospital-acquired infections, in which biofilm production plays a critical role in nosocomial transmission and pathogenicity. Although genotypic heterogeneity among C. striatum clinical isolates has been increasingly recognized, factors influencing isolate-specific biofilm formation, particularly host-derived factors, remain poorly understood. This study investigated the biofilm formation characteristics of C. striatum isolates with distinct genotypic and phenotypic profiles under exposure to human plasma proteins.

Methods

Sixty clinical C. striatum isolates were collected from inpatients at the Affiliated Hospital of Inner Mongolia Medical University between December 2013 and August 2022. The isolates, subcultured onto blood agar plates and the single colonies, were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antimicrobial susceptibility testing was conducted using the microbroth dilution method. Whole-genome sequencing was performed to assess genetic relatedness and to identify virulence and antibiotic resistance genes. Biofilm formation was evaluated using Congo red agar and crystal violet assays in the presence or absence of fibronectin or fibrinogen.

Results

Phylogenomic analysis classified the 60 C. striatum isolates into five evolutionary clades (I–V), with Clade I as the dominant lineage (45%, 27/60). Biofilm assays showed that 95% (57/60) of C. striatum isolates were biofilm producers, of which 56.14% (32/57) were moderate or strong producers. Notably, 92.59% (25/27) of Clade I isolates exhibited moderate or strong biofilm formation. Multidrug resistance was observed in 95% (57/60) of isolates, with high resistance rates to ciprofloxacin, cefepime, and ceftriaxone. Virulence gene distribution varied significantly across clades, with spaDEF (96.30%) and whiB3 (100%) being highly prevalent in Clade I. Proteinase K showed the strongest biofilm-degrading activity. Exposure to fibronectin or fibrinogen (50 µg/mL) enhanced biofilm formation in 47.37% (27/57) of isolates, whereas biofilm density decreased significantly in most strong biofilm-producing Clade I isolates.

Conclusions

This study reveals significant genomic heterogeneity among C. striatum clinical isolates and their association with biofilm formation. Importantly, it demonstrates isolate- and genotype-dependent effects of human plasma proteins on C. striatum biofilm production, highlighting the potential roles of spaDEF and whiB3 in pathogenicity.