Fecal Microbiota Transplantation for Recurrent Clostridioides difficile Infections in a Cystic Fibrosis Child Previously Screen Positive, Inconclusive Diagnosis (CFSPID): A Case Report

<i>Clostridioides difficile</i> infection (CDI) is generally treated with vancomycin, metronidazole or fidaxomicin, although fecal microbiota transplantation (FMT) represents a promising therapeutic option for antibiotic-resistant recurrent <i>C. difficile</i> infections (rCDIs) in adults. In pediatric cystic fibrosis (CF) patients, CDIs are generally asymptomatic and respond to treatment. Here, we present the case of an 8-year-old female, initially diagnosed as "CFTR-related metabolic syndrome/cystic fibrosis screen positive, inconclusive diagnosis" (CMRS/CFSPID), who then progressed to CF at 12 months. In the absence of CF-related symptoms, she presented multiple and disabling episodes of bloody diarrhoea with positive tests for <i>C. difficile</i> antigen and A/B toxin. After conventional treatments failed and several CDI relapses, FMT was proposed. Donor screening and GM donor-receiver matching identified her mother as a donor. Metataxonomy and targeted metabolomics provided, through a pre- and post-FMT time course, gut microbiota (GM) profiling to assess GM engraftment. At first, the GM map revealed severe dysbiosis, with a prevalence of Bacteroidetes and Proteobacteria (i.e., <i>Klebsiella</i> spp., <i>Escherichia coli</i>), a reduction in Firmicutes, a GM nearly entirely composed of Enterococcaceae (i.e., <i>Enterococcus</i>) and an almost complete depletion of Verrucomicrobia and Actinobacteria, mostly represented by <i>Veillonella dispar</i>. Post FMT, an increment in <i>Bifidobacterium</i> spp. and <i>Collinsella</i> spp. with a decrease in <i>V. dispar</i> restored intestinal eubiosis. Consistently, four weeks after FMT treatment, the child's gut symptoms cleared, without CDI recurrence.