Abstract: We thank Jean Christophe Lagier and Didier Raoult for their interest in our Review1Allegretti JR Mullish BH Kelly C Fischer M The evolution of the use of faecal microbiota transplantation and emerging therapeutic indications.Lancet. 2019; 394: 420-431Summary Full Text Full Text PDF PubMed Scopus (160) Google Scholar and for highlighting the growing interest in the use of faecal microbiota transplantation as a treatment option for recurrent urinary tract infections. The hypothesis for this potential treatment strategy is that bacteria within the family of Enterobacteriaceae, which includes pathogenic bacteria that commonly cause urinary tract infections, can migrate to the urinary tract from a reservoir within the gut microbiota. Notably, successful faecal microbiota transplantation for the treatment of recurrent Clostridioides difficile infection is associated with a marked reduction in the relative abundance of Enterobacteriaceae within the gut microbiota,2Mullish BH McDonald JAKK Pechlivanis A et al.Microbial bile salt hydrolases mediate the efficacy of faecal microbiota transplant in the treatment of recurrent Clostridioides difficile infection.Gut. 2019; 68: 1791-1800Crossref PubMed Scopus (124) Google Scholar and could therefore be a rational approach for intestinal decolonisation of these organisms. Many patients with recurrent urinary tract infections have infections caused by multidrug-resistant bacteria, a consequence of prolonged exposure to antimicrobials. The demonstration that successful faecal microbiota transplantation can be associated with loss of antibiotic resistance genes within the gut microbiota3Millan B Park H Hotte N et al.Fecal microbial transplants reduce antibiotic-resistant genes in patients with recurrent Clostridium difficile infection.Clin Infect Dis. 2016; 62: 1479-1486Crossref PubMed Scopus (128) Google Scholar has further fuelled interest in the potential use of faecal microbiota transplantation for this indication. However, it is important to temper enthusiasm, recognising that the evidence in this area remains at a nascent phase. Many studies in this field to date are case reports and small case series with limited follow-up. The only randomised study published to date of faecal microbiota transplantation for intestinal decolonisation of multidrug-resistant Enterobacteriaceae showed no significant difference in decolonisation rates between patients treated with faecal microbiota transplantation compared with those receiving no intervention; a high spontaneous decolonisation rate was also reported (29%).4Huttner BD de Lastours V Wassenberg M et al.A 5-day course of oral antibiotics followed by faecal transplantation to eradicate carriage of multidrug-resistant Enterobacteriaceae: a randomized clinical trial.Clin Microbiol Infect. 2019; 25: 830-838Summary Full Text Full Text PDF PubMed Scopus (94) Google Scholar As discussed in our Review,1Allegretti JR Mullish BH Kelly C Fischer M The evolution of the use of faecal microbiota transplantation and emerging therapeutic indications.Lancet. 2019; 394: 420-431Summary Full Text Full Text PDF PubMed Scopus (160) Google Scholar priorities for future research in this area, as well as others being explored, require randomised trials that are adequately powered, with appropriate controls and carefully considered endpoints, and patient follow-up to make meaningful conclusions about both clinical efficacy and safety. JRA consults for Pfizer, Takeda, Janssen, and Merck and Finch Therapeutics. BHM is the recipient of a National Institute for Health Research (NIHR) Academic Clinical Lectureship. The Department of Metabolism, Digestion, and Reproduction at Imperial College receives financial support from the NIHR Imperial Biomedical Research Centre based at Imperial College Healthcare National Health Service Trust and Imperial College London. Faecal microbiota transplantations and urinary tract infectionsWe read with interest the report by Jessica R Allegretti and colleagues1 on the different indications of the faecal microbiota transplantation. Nevertheless, in our opinion, the authors have neglected related discoveries, made serendipitously, during a faecal microbiota transplantation. Full-Text PDF The evolution of the use of faecal microbiota transplantation and emerging therapeutic indicationsDevelopments in high-throughput microbial genomic sequencing and other systems biology techniques have given novel insight into the potential contribution of the gut microbiota to health and disease. As a result, an increasing number of diseases have been characterised by distinctive changes in the composition and functionality of the gut microbiota; however, whether such changes are cause, consequence, or incidental to the disease in question remains largely uncertain. Restoration of the gut microbiota to a premorbid state is a key novel therapeutic approach of interest, and faecal microbiota transplantation—the transfer of prescreened stool from healthy donors into the gastrointestinal tract of patients—is gaining increasing importance in both the clinical and research settings. Full-Text PDF