A world inside : Gastrointestinal microbiota in healthy Swedish children at day care centers and aspects on antibiotic resistance, enteric pathogens and transmission

Sammanfattning: Antibiotic resistance is a growing threat to human health and is defined by the World Health Organization as a crisis that must be managed with the utmost urgency. Antibiotic resistant bacteria increase both mortality and morbidity and have a great impact on the global economy. Resistance is not confined to human health care, but is present also among animals and in our environment at large. Indeed, resistant bacterial strains have now been found in virtually all parts of the world, even in locations without direct human contact.The human gastrointestinal tract is populated by a complex, dynamic, diverse and highly interactive collection of microorganisms, including bacteria, archaea, fungi, yeasts and viruses, which constitutes our gastrointestinal microbiota. This microbiota is an important reservoir of resistance genes (our gastrointestinal resistome) and a “melting pot” for transfer of resistance genes between microbes, including potential pathogens.In this thesis I investigated the prevalences of two clinically important kinds of antibiotic resistance: extended-spectrum β-lactamases (ESBL) and vancomycin-resistant enterococci (VRE), as well as asymptomatic carriage of potential enteropathogens among healthy preschool children in Uppsala. Fecal samples from unidentified, individual diapers were collected in 2010 (125+313 samples) and in 2016 (334 samples). In addition, 204 environmental samples from the children’s preschools were collected in autumn 2016.A prevalence of 2.9% ESBL-producing Enterobactericeae was demonstrated in the first samples from 2010. No VRE were found and the occurrence of enteropathogens were reassuringly low. Results on ESBL prevalence in 2016 and transmission of resistance between children will be presented when the manuscript is published and at the dissertation.