Molecular characterization and genotyping of isolates from cancer patients with Clostridioides difficile infection or asymptomatic colonization

Introduction. Cancer patients with Clostridioides difficile infection (CDI) are at a higher risk for adverse outcomes. In addition, a high prevalence of Clostridioides difficile asymptomatic colonization (CDAC) has been reported in this vulnerable population. Gap Statement. The molecular characteristics and potential role of CDAC in healthcare-related transmission in the cancer population have been poorly explored. Aim. We aimed to compare the molecular and genotypic characteristics of C. difficile isolates from cancer patients with CDAC and CDI. Method. We conducted a prospective cohort study of cancer patients with CDAC or CDI from a referral centre. Molecular characterization, typification and tcdC gene expression of isolates were performed. Results. The hospital-onset and community-onset healthcare facility-associated CDI rates were 4.5 cases/10000 patient-days and 1.4 cases/1 000 admissions during the study period. Fifty-one C. difficile strains were isolated: 37 (72%) and 14 (28 %) from patients with CDI or CDAC, respectively. All isolates from symptomatic patients were tcdA+/tcdB+, and four (10 %) were ctdA+/ctdB+. In the CDAC group, 10 (71 %) isolates were toxigenic, and none were ctdA+/ctdB+. The Delta 18 in-frame tcdC deletion and two transition mutations were found in five isolates. After bacterial typing, 60% of toxigenic isolates from asymptomatic carriers were clonal to those from patients with C. difficile-associated diarrhoea. No NAP1/027/BI strains were detected. Conclusions. We found a clonal association between C. difficile isolates from patients with CDAC and CDI. Studies are needed to evaluate the potential role of asymptomatic carriers in the dynamics of nosocomial transmission to support infection control measures and reduce the burden of CDI in high-risk groups.