Use of phenotypic and genomic tools to study the prevalence and transmission of antibiotic resistance in a One Health concept
Multidrug resistance is increasingly observed in human and veterinary medicine worldwide. This major public health challenge is a One Health issue connecting humans, animals and the environment. Insights into the levels of antibiotic resistance in One Health sectors and the pathways that lead to the spread of antibiotic resistance will guide control strategies leading to improved patient care as well as public and animal health. We employed both phenotypic methods and genomics to investigate the occurrence of antibiotic resistance, the antibiotic use and the dynamics of transmissible resistance genes or isolates within the human and veterinary sectors in Belgium and the Netherlands using a One Health approach. In this work, we identified and characterized extended-spectrum beta-lactamase (ESBL)-producing, ciprofloxacin-resistant and colistin-resistant Enterobacterales from animals and humans. The carriage of colistin-resistant bacteria by hospitalized patients, healthy individuals from the community and livestock showed that resistance is present in all sectors examined. However, remarkable differences in antibiotic use and resistance were observed between countries and farms. Livestock is a reservoir for a large variety of antimicrobial resistance genes, virulence genes and plasmids. Resistance was spread within a multifaceted landscape of transmission pathways involving both dissemination or a common source of resistant clones and horizontal transfer of plasmids. The complex epidemiology of antibiotic resistance in farms makes it difficult to translate these findings to the impact on human health. However, the pandemic multidrug-resistant clone E. coli ST131 and blaCTX M-15 commonly associated with human infections was rarely found in livestock. Additionally, animal-to-human transmission or vice versa was not detected. Genomic analysis of a global collection of K. pneumoniae ST101 identified ICEKp harboring the yersiniabactin siderophore as a key virulence factor present in hospital-associated isolates. The absence of this siderophore in livestock-associated, community-associated, and food-associated isolates indicates a lower virulence capacity compared to hospital-associated isolates. Taken together, the presence of resistant bacteria in the examined One Health sectors seems to reflect the antibiotic pressure in each sector rather than transmission of resistant isolates between sectors. In conclusion, this thesis provides insights into the carriage of antibiotic-resistant Gram-negative bacteria by humans and animals and contributes to an improved understanding of the underlying resistance mechanisms and spread of resistance in all One Health sectors involved.
Antwerp : University of Antwerp, Faculty of Medicine and Health Sciences , 2023
XXX, 250 p.
Supervisor: Goossens, Herman [Supervisor]
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Creation 19.09.2023
Last edited 29.09.2023
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