Abstract
Clostridioides difficile (formerly called Clostridium difficile, C. difficile) infection (CDI) is listed as an urgent threat on the 2019 antibiotic resistance threats report in the United States by the Centers for Disease Control and Prevention. Early detection and appropriate disease management appear to be essential. Meanwhile, although the majority of cases are hospital-acquired CDI, community-acquired CDI cases are also on the rise, and this vulnerability is not limited to immunocompromised patients. Gastrointestinal treatments and/or gastrointestinal tract surgeries may be required for patients diagnosed with digestive diseases. Such treatments could suppress or interfere with the patient's immune system and disrupt gut flora homeostasis, creating a suitable microecosystem for C. difficile overgrowth. Currently, stool-based non-invasive screening is the first-line approach to CDI diagnosis, but the accuracy is varied due to different clinical microbiology detection methods; therefore, improving reliability is clearly required. In this review, we briefly summarised the life cycle and toxicity of C. difficile, and we examined existing diagnostic approaches with an emphasis on novel biomarkers such as microRNAs. These biomarkers can be easily detected through non-invasive liquid biopsy and can yield crucial information about ongoing pathological phenomena, particularly in CDI.