Refractory giardiasis: Exploring the contribution of bacterial community shifts.
Travel Med Infect Dis 2026; 71:102983.

Abstract

Giardia duodenalis infection is a common cause of diarrhoea in returning travellers from low-income regions. The increasing prevalence of resistance to nitroimidazoles, as first-line therapy, are of global concern. The interaction between Giardia and the host's gut microbiota plays a crucial role in the pathophysiology of giardiasis. Yet, longitudinal data assessing the course of the infection are scarce, and non-existent in patients refractory to treatment. Here, we provide the first longitudinal bacterial community study, carried out in two Giardia-infected Spanish adult patients refractory to treatment after travelling to India, a Giardia-hyperendemic country, which offers insights into the gut microbiota's response to infection and therapy over time. A significant reduction in alpha diversity was evidenced during and post-infection, accompanied by changes in bacterial taxa contribution, with an important individual effect. We evidenced microbial shifts that may be associated with infection, treatment effectiveness or microbial restoration after infection, which can potentially be used to monitor disease evolution and adjust the therapeutic strategy.

Authors+Show Affiliations

Alberca-Ballell MBiosciences Department, Bi-Squared Research Group, Faculty of Sciences, Technology and Engineering, Universitat de Vic - Universitat Central de Catalunya, Vic, Spain.
López-Siles MMicrobiology of Intestinal Diseases Group, Biology Department, Universitat de Girona, Girona, Spain.
Stensvold CRDepartment of Bacteria, Parasites, and Fungi, Statens Serum Institut, Copenhagen, Denmark.
Arenal-Andrés NDepartment of Microbiology and Parasitology, Complejo Asistencial de Segovia, Segovia, Spain.
San Miguel-Sebastián NDepartment of Microbiology and Parasitology, Santos Reyes Hospital, Aranda de Duero, Spain.
Köster PCParasitology Reference and Research Laboratory, National Centre for Microbiology, Institute of Health Carlos III, Majadahonda, Spain; Faculty of Health Sciences, Alfonso X El Sabio University (UAX), Villanueva de la Cañada, Spain.
Sánchez SParasitology Reference and Research Laboratory, National Centre for Microbiology, Institute of Health Carlos III, Majadahonda, Spain.
Martín-Galiano AJCore Scientific and Technical Units, Instituto de Salud Carlos III, Majadahonda, Spain.
Llirós-Dupré MBiosciences Department, Bi-Squared Research Group, Faculty of Sciences, Technology and Engineering, Universitat de Vic - Universitat Central de Catalunya, Vic, Spain. Electronic address: marc.lliros@uvic.cat.
Carmena DParasitology Reference and Research Laboratory, National Centre for Microbiology, Institute of Health Carlos III, Majadahonda, Spain; Centre for Biomedical Research Network (CIBER) in Infectious Diseases, Health Institute Carlos III, Madrid, Spain. Electronic address: dacarmena@isciii.es.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

42070714