# Characterization of the clade 4 non-toxigenic C. difficile isolate L-NTCD03 carrying the cfr(B) gene

## TL;DR

This study characterizes a non-toxigenic strain of Clostridioides difficile, L-NTCD03, which could be useful for developing new therapies.

## Contribution

The study provides a detailed genomic and functional analysis of a non-toxigenic C. difficile strain carrying the cfr(B) gene.

## Key findings

- L-NTCD03 is a non-toxigenic C. difficile strain resistant to multiple antimicrobials.
- The cfr(B) gene in L-NTCD03 confers resistance to clindamycin, linezolid, retapamulin, and streptogramin A.
- L-NTCD03 is a potential candidate for developing live biotherapeutic products.

## Abstract

Clostridioides difficile infection (CDI) is a toxin-mediated gastro-intestinal disease. Yet, C. difficile is a phylogenetically diverse species that includes many non-toxigenic strains. In general, these are understudied, despite having significant potential impact for our understanding of the colonization process and as therapeutic modalities. Here, we present an in-depth characterization—including the complete genome sequence—of the non-toxigenic C. difficile strain L-NTCD03. This strain belongs to PCR ribotype 416, clade 4 and multilocus sequence type 39. It is resistant to multiple antimicrobials, but not those used for treatment of CDI. We validated the relevance of the cfr(B) gene from this strain in antimicrobial resistance to clindamycin, linezolid, retapamulin, and streptogramin A. We found the L-NTCD03 strain to be non-toxic in various assays. Altogether, L-NTCD03 is a promising candidate for developing into a live biotherapeutic product.

This manuscript describes characteristics of the clade 4 non-toxigenic Clostridioides difficile isolate L-NTCD03.