The characteristics of Clostridium difficile ST81, a new PCR ribotype of toxin A- B+ strain with high-level fluoroquinolones resistance and higher sporulation ability than ST37/PCR ribotype 017

Abstract

Antibiotic exposure, Clostridium difficile toxins, and spore formation are key factors involved in the pathogenesis of Clostridium difficile infection (CDI). A high incidence of CDI due to toxin A- B+ strains, which were classified into two genotypes (ST81 and ST37) by multilocus sequence typing, was identified in Beijing Friendship Hospital in 2016-2017. ST81 was the most prevalent type, accounting for 81.25% of toxin A- B+ strains. ST81 corresponded to a novel PCR ribotype, PKI-017, with one less band than ST37/ribotype 017 in PCR ribotyping. All ST81 strains showed a high level of ciprofloxacin resistance (MICs ≥ 64 μg mL-1) and moxifloxacin resistance (MICs ≥ 128 μg mL-1) with the amino acid substitutions Thr82 to Ile in GyrA and Ser416 to Ala in GyrB. There was either no mutation or only the single amino acid mutation Thr82 to Ile in the GyrA subunit of ST37/ribotype 017 strains, which had lower MICs of ciprofloxacin (4-64 μg mL-1) and moxifloxacin (4-16 μg mL-1). In addition, ST81 strains exhibited higher spore formation ability than ST37/ribotype 017 strains. Overall, our results indicated that ST81 strains had unique characteristics distinguishable from ST37 strains and emphasized the importance of ongoing surveillance for this new genotype.

Global Evolution of Pathogenic Bacteria With Extensive Use of Fluoroquinolone Agents

“…The recently observed widespread dissemination of the ribotype 017 clone of C. difficile in Asia (Imwattana et al, 2019) may also be associated with the "fluoroquinolone influence". Ribotype 017 and other expanding-clone strains were reported to mostly carry the favorable gyrA Thr82Ile mutation in various Asian countries (Lee et al, 2014;Wang et al, 2018).…”

Clostridium difficile ribotype 017 – characterization, evolution and epidemiology of the dominant strain in Asia

“…Interestingly, in 2001, there was an outbreak of CDI caused by an A-B+ strain of C. difficile with an RT pattern resembled C. difficile RT 017 [91]. This strain was later identified as the novel C. difficile RT 369, a strain that is closely related to C. difficile RT 017 [36], and that was recently identified in China as ST 81, a single loci variant of ST 37 [92]. To date, RT 369 remains among the most common toxigenic strains isolated in Japan while only a small number of C. difficile strains belonging to RT 017 have been detected [93].…”

Clostridium difficile in Asia: Opportunities for One Health Management

“…RT 369 has since been reported in studies from China as the cause of a nosocomial outbreak among hospital patients in Shanghai in 2014 and 2015 where it was the most common strain in circulation. RT 369/ST81 strains are also reported to have higher rates of resistance to clindamycin, ciprofloxacin and moxifloxacin compared with other strains, and a higher sporulation rate than RT 017/ST37 strains [63,64].…”