OBJECTIVE To understand the molecular epidemiological characteristics, antimicrobial sensitivity and resistance mechanisms of Clostridioides difficile in Xi′an region, and provide data support for the prevention and control of C. difficile infection and the rational clinical use of antibiotics.

METHODS A total of 87 strains of C. difficile, which were successfully isolated from stool samples collected from 6 hospitals from Oct. 2018 to Dec. 2022, were tested for virulence genes, population structure and genetic diversity were detected by Multilocus sequence typing (MLST) and Ribotyping (RT) methods, the drug sensitivity was detected by Etest, additionally, amino acid variations in the quinolone resistance-determining regions GyrA and GyrB were detected.

RESULTS There were 41 strains (62.12%) with the genotype A+B+CDT-, 23 strains (34.85%) with the genotype A-B+CDT-, and 2 strains (3.03%) with the genotype A+B+CDT+. MLST was divided into 25 ST types, and the main types were ST3, ST42 and ST39. There were 37 RT types, mainly were RT012, RT106 and RT001. All strains were sensitive to vancomycin and metronidazole, and the resistance rates to ciprofloxacin, levofloxacin and moxifloxacin were 90.80%, 28.73% and 21.84%, respectively. GyrA contains two amino acid variations at Thr82-Ile and Asp205-Glu, and GyrB contains 6 amino acid variations.

CONCLUSIONS The predominant toxin-producing strain of C. difficile in Xi′an is of A+B+CDT- genotype and the primary molecular types are ST54/RT012, ST42/RT106, ST3/RT001 and ST37/RT017. No strains resistant to vancomycin or metronidazole are detected. Amino acid variations in GyrA or GyrB of C. difficile are associated with quinolone resistance. To effectively prevent the outbreak of C. difficile infection, it is crucial to enhance molecular epidemiology studies and strengthen antimicrobial resistance surveillance efforts.