Long-Term Antibiotic-Driven Gut Microbiota Disruption Promotes Toxigenic Clostridioides difficile Proliferation: A Four-Year Retrospective Study of a Single ICU Patient

Xinrong Jiang,1 Lechi Wu,1 Simiao Duan,1 Junyu Bian,1 Tao Lv,1 Lisi Zheng,1 Yuhong Zhao,2 Ping Shen,1 Jianqin He,1 Yunbo Chen1 1State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People’s Republic of China; 2Department of Blood Transfusion, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People’s Republic of ChinaCorrespondence: Jianqin He; Yunbo Chen, Email [email protected]; [email protected]: This four-year longitudinal study of a single critically ill patient leverages deep temporal profiling to unravel the dynamic interplay between antibiotic pressure, gut microbiota, and Clostridioides difficile (C. difficile) colonization, providing temporal insights unattainable through cross-sectional designs.Methods: We performed a retrospective analysis of one critically ill patient (2015– 2019). Sixty-four fecal samples were subjected to toxigenic C. difficile culture and metagenomic sequencing. To isolate short-term effects, we implemented a 7-day retrospective window, categorizing each sample based on antibiotic exposure in the preceding week: no antibiotics, monotherapy, or polypharmacy.Results: Antibiotic exposure significantly reduced microbial diversity and promoted dysbiosis. Crucially, we identified a transitional C. difficile colonization state (Tcd±) that potentially determines progression to toxigenic (Tcd+) or non-toxigenic (Tcd-) outcomes. Analysis using the 7-day window revealed that intensive antibiotic pressure was strongly associated with successional progression towards toxigenic dominance. Conversely, brief antibiotic-free intervals were linked to partial restoration of microbial network complexity and a competitive landscape favoring non-toxigenic strains.Conclusion: This deep temporal profiling of a single case provides novel, hypothesis-generating insights. The identification of a transitional colonization state and the association between short-term antibiotic pressure and colonization outcomes define critical dynamics for future validation. These findings highlight the potential of longitudinal data to inform precise antibiotic stewardship strategies in high-risk, critically ill populations.Keywords: Clostridioides difficile, antibiotics use, gut microbiota, metagenomic, critically ill patient