Extended-spectrum beta-lactamase (ESBL)-producing Escherichia (E.) coli have been widely described as the cause of treatment failures in humans around the world. The origin of human infections with these microorganisms is discussed controversially and in most cases hard to identify. Since they pose a relevant risk to human health, it becomes crucial to understand their sources and the transmission pathways. In this study, we analyzed data from different studies in Germany and grouped ESBL-producing E. coli from different sources and human cases into subtypes based on their phenotypic and genotypic characteristics (ESBL-genotype, E. coli phylogenetic group and phenotypic antimicrobial resistance pattern). Then, a source attribution model was developed in order to attribute the human cases to the considered sources. The sources were from different animal species (cattle, pig, chicken, dog and horse) and also from patients with nosocomial infections. The human isolates were gathered from community cases which showed to be colonized with ESBL-producing E. coli. We used the attribution model first with only the animal sources (Approach A) and then additionally with the nosocomial infections (Approach B). We observed that all sources contributed to the human cases, nevertheless, isolates from nosocomial infections were more related to those from human cases than any of the other sources. We identified subtypes that were only detected in the considered animal species and others that were observed only in the human population. Some subtypes from the human cases could not be allocated to any of the sources from this study and were attributed to an unknown source. Our study emphasizes the importance of human-to-human transmission of ESBL-producing E. coli and the different role that pets, livestock and healthcare facilities may play in the transmission of these resistant bacteria. The developed source attribution model can be further used to monitor future trends. A One Health approach is necessary to develop source attribution models further to integrate also wildlife, environmental as well as food sources in addition to human and animal data.

No abstract

No abstract

Direct contact between humans and live broilers, as well as the consumption of chicken meat, have been suggested as pathways for transmission of extended-spectrum-β-lactamase (ESBL) and AmpC-β-lactamase (AmpC)-producing Escherichia coli. One approach to design intervention strategies to control the transmission of such bacteria between animals and humans is to study the transmission pathways of such bacteria between the animals themselves. The rationale is that controlling the process of the underlying source, here transmission between animals, can provide hints on how to control a higher-level process, here the transmission between animals and humans. The focus of this article is the transmission of the above-mentioned bacteria between broilers and broiler flocks in meat production with regards to the establishment of possible intervention strategies to reduce the transfer of these bacteria between animals. The objective of this work is to design a mathematical transmission model describing the effects of vertical and horizontal bacterial transmission in the broiler production chain, from the parent generation to the slaughterhouse level. To achieve this objective, an existing transmission model for Campylobacter was adapted for the case of E. coli. The model keeps track of prevalence among flocks (flock prevalence) and of prevalence among animals within one flock (animal prevalence). Flock and animal prevalences show different dynamics in the model. While flock prevalence increases mainly through horizontal transmission in hatcheries, animal prevalence increases mainly at the broiler-fattening farm. Transports have rather small effects just as the vertical transmission from parents to chicks.