Local outbreak of Clostridioides difficile PCR-Ribotype 018 investigated by multi locus variable number tandem repeat analysis, whole genome multi locus sequence typing and core genome single nucleotide polymorphism typing.

The prevalence of Clostridioides difficile PCR-ribotype (RT) 018 is low in Europe but variations are observed across countries. We report here the first RT 018-related outbreak in France that took place in 4 geriatric units (GU) in Strasbourg, France. From January to December 2017, 38 patients were diagnosed with C. difficile infection (CDI). Strains were first characterized by PCR ribotyping: 19 out of 38 (50%) strains belonged to RT 018. These strains as well as 12 RT 018 isolated in other French healthcare facilities and 2 strains of RT 018 isolated in the GU in 2015 were characterized by multi locus variable-number tandem repeat (VNTR) analysis (MLVA), whole genome multi locus sequence typing (wgMLST) and core genome single nucleotide polymorphism typing (cgSNP). The MLVA indicated that 15 out of 19 epidemic strains of RT 018 were included in 2 Clonal Complexes (CC). Four RT 018 strains from the outbreak did not belong to the CC. The wgMLST and cgSNP typing analysis revealed a single CC that included 19 strains from the geriatric unit (17 from GU in 2017 and 2 from GU in 2015) and 4 strains (33%) from other healthcare facilities (HCF). Our results suggest that a specific RT 018 clone has spread in the geriatric unit and has evolved slowly over time. MLVA, wgMLST and cgSNP typing results provided fairly consistent information but wgMLST and cgSNP typing better separated epidemic strains from non-epidemic strains. Compared to wgMLST, the cgSNP typing did not provide additional information.

Characterization of Non-Toxigenic Clostridioides difficile Strains Isolated from Preterm Neonates and In Vivo Study of Their Protective Effect.

In a previous monocentric study in preterm neonates (PN), we described a high Clostridioides difficile colonization rate (74%) with two uncommon non-toxigenic strains (NTCD) belonging to PCR-ribotype (RT) (CE)847 and (CE)032. To determine the extent of carriage of both NTCD in other spatio-temporal settings, strains isolated in PN stools from two multicenter cohorts were characterized by PCR-ribotyping, MLVA and MLST. We also evaluated the protective role of two NTCD from these RT against C. difficile infection in a hamster caecitis model. Animals were administered either each NTCD alone (n = 7), or followed by a 027 strain (n = 9). A control group received only the 027 strain (n = 8). Clinical activity and colonization by C. difficile in stools were monitored daily until death or sacrifice at D20. We isolated 18 RT(CE)032 (ST-83) strains and 2 RT(CE)847 (ST-26) strains among 247 PN from both cohorts. Within each RT, strains were genetically related. The survival rate was significantly increased when animals received a RT(CE)847 or (CE)032 strain before the 027 strain (4/9 deaths, p = 0.029; 1/9 death, p = 0.0004, respectively). We describe two predominant uncommon NTCD strains, in a PN population from different healthcare facilities. Both NTCD provide a potential protection against C. difficile infection.