Clostridioides difficile infection (CDI) remains a major global public health challenge because of high recurrence rates associated with spore germination, biofilm formation, and antibiotic resistance. Microplastics, including polystyrene microplastics (PS-MPs), are increasingly recognized as foodborne contaminants. This study investigated whether PS-MPs affect CD pathogenicity, biofilm dynamics, and antimicrobial susceptibility, exploring molecular and phenotypic changes induced by PS-MPs exposure.
Exposure of CD to PS-MPs across a tested range (0–400 μg/mL) caused intracellular oxidative stress. The authors report that this oxidative stress correlated with increased bacterial proliferation and enhanced biofilm formation. The study presents PS-MPs as a factor that can directly modulate CD physiology in vitro, promoting conditions that favour biofilm development, which is relevant to persistence and recurrence of CDI.
PS-MPs exposure upregulated quorum-sensing genes, specifically agrD and luxS, and increased secretion of the autoinducer AI-2. These quorum-sensing changes were associated with augmented bacterial motility. Together, the data indicate that PS-MPs can activate cell–cell communication pathways in CD, which likely contribute to coordinated behaviours such as biofilm assembly and dispersal.
The investigators observed increased expression of virulence-related and sporulation genes, including Spo0A, following PS-MPs exposure. Functionally, these transcriptional changes corresponded to intensified cytotoxic effects on human intestinal epithelial cell lines (HT-29 and Caco-2). Thus, PS-MPs not only altered CD regulatory networks but also increased measurable damage to intestinal epithelial cells in vitro.
Antimicrobial susceptibility testing demonstrated that both short-term (48 h) and long-term (20 d) exposure to PS-MPs significantly increased the half-inhibitory concentration (IC50) of CD against seven tested antibiotics. Of particular clinical note, long-term exposure to 100 μg/mL PS-MPs produced a 2.42-fold increase in the IC50 for vancomycin. This increased tolerance was accompanied by upregulation of resistance-associated genes, including tetW, gyrA, and gyrB. The authors conclude that PS-MPs exposure can attenuate antibiotic susceptibility in CD and promote expression of specific resistance determinants.
Taken together, the reported findings propose a mechanistic chain in which PS-MPs induce oxidative stress in CD, activating quorum-sensing systems and promoting biofilm formation. These changes amplify bacterial proliferation, motility, virulence expression, sporulation, and tolerance to multiple antibiotics. The study frames environmental microplastic pollution as both a physical vector and a direct modulator of CD pathogenicity and antimicrobial resistance, implying that microplastics in the food chain may increase CDI recurrence risk and complicate treatment outcomes.
The abstract provides robust summaries of experimental findings, but many methodological specifics are not reported in the source text provided here. The following details were not reported in the abstract and therefore cannot be restated from this source: exact experimental protocols (culture conditions, strains used, biofilm quantification methods), identities and concentrations of the seven antibiotics tested beyond vancomycin, statistical analyses, in vivo validation or clinical correlation data, and any detailed time-course or dose–response curves beyond the summary concentrations and time points noted (0–400 μg/mL; 48 h; 20 d; 100 μg/mL long-term). Readers should consult the full text for complete methods, raw data, and supplementary analyses.
This study reports that polystyrene microplastics promote intracellular oxidative stress in Clostridioides difficile, leading to activation of quorum-sensing pathways, enhanced biofilm formation, increased motility, upregulation of virulence and sporulation genes, greater cytotoxicity to intestinal epithelial cells, and reduced susceptibility to multiple antibiotics. Notably, long-term exposure to 100 μg/mL PS-MPs produced a 2.42-fold increase in vancomycin IC50 with concurrent upregulation of tetW, gyrA, and gyrB. The results link environmental microplastic contamination to potential increases in CDI recurrence risk and therapeutic challenges. For experimental details and full datasets, consult the original publication.