Genomic Epidemiology and Antimicrobial Resistance Profiles of

Clostridioides difficile is an important pathogen causing approximately 20-30% of the cases-with antibiotic-associated diarrhea and 90% of those with Pseudomembranous enteritis. However, limited surveillance of C. difficile infections (CDI) in China is done at present, especially in terms of multi-hospital epidemiological reports.

Between June 2020 and November 2020, we conducted a prospective study addressing antimicrobial susceptibility profiles and genomic epidemiology of C. difficile strains isolated from inpatients with diarrhea in seven tertiary hospitals in the same city.

In total, 177 strains of toxin-producing C. difficile were isolated, and the dominant toxin gene profiles were tcdA+tcdB+ (84.2%, 149/177) and tcdA-tcdB+ (15.8%, 28/177). Furthermore, 130 isolates were successfully analyzed for antimicrobial susceptibility phenotype in which the rates of resistance to clindamycin, erythromycin, levofloxacin, and moxifloxacin were higher than to other antibiotics. All strains were susceptible to metronidazole and vancomycin. Fluoroquinolone-associated mutations (such as gyrA) were the most frequently found ones in the analyzed genomes. Moreover, 24 different sequence types (STs) were identified in the 130 isolates, and the most prevalent types were ST3 (26.2%, 34/130) followed by ST54 (16.9%, 22/130) and ST2 (10%, 13/130). The so-called highly virulent strain ribotyping 027 (B1/NAP1/ST1) was not identified. In addition, we also compared single nucleotide polymorphisms (SNPs) among the isolates and carried out genomic epidemiological studies on the isolates. We found that ST3 and ST54 could cause transmission in both intra- and inter-hospital settings.

Although it is the so-called hypervirulent epidemic strain, ribotyping 027 (ST1), was not detected. ST3 and ST54 can be transmitted through different hospitals. Therefore, it is necessary to conduct further molecular epidemiological monitoring of C. difficile and screening of patients admitted to key departments.