Understanding and Modelling Reservoirs, Vehicles and Transmission of ESBL‑Producing Enterobacteriaceae in Community and LTCFs (MODERN)

The MODERN project is a multicentre collaborative study, led by REIPI in partnership with institutions in Spain, Germany, Switzerland, France, the Netherlands and the UK, aimed at characterizing the reservoirs and transmission dynamics of extended-spectrum β-lactamase–producing Enterobacteriaceae (ESBL‑PE) in community and long‑term care facility (LTCF) settings (visavet.es).
Key aims include:

Quantifying colonization and transmission risk factors within households and LTCFs—especially following hospital discharge of ESBL‑PE–positive individuals.
Identifying environmental vehicles of ESBL‑PE spread, including wastewater, human‑polluted urban sites, food items, and surface contamination.
Applying advanced molecular typing and resistome analyses to characterize bacterial clones (e.g. E. coli ST131, K. pneumoniae) and mobile resistance determinants across human and non‑human reservoirs (gesundheitsforschung-bmftr.de, ResearchGate).
Developing mathematical models to simulate transmission pathways and evaluate the potential impact of intervention strategies in different European contexts.

Study Design & Methods

Multinational, prospective observational cohorts including ESBL‑PE–positive index patients from hospital settings and their household or LTCF contacts across five European urban regions: Seville (Spain), Tübingen (Germany), Geneva (Switzerland), Besançon (France), and Utrecht (Netherlands) (data.snf.ch, ResearchGate).
Multi‑compartment sampling: faecal swabs (index cases and contacts), environmental samples (wastewater, surfaces), food specimens in defined catchment areas.
Longitudinal follow-up of households and LTCF residents over several months to track acquisition, persistence, and clearance of ESBL‑PE.
Whole‑genome sequencing and phylogenetic studies, including cgMLST and plasmid profiling, to assess clonal relationships and the sharing of antimicrobial‑resistance genes (ARGs) across sources (ResearchGate).

Key Findings to Date

High prevalence of intestinal carriage: Over 16% of LTCF residents and one-quarter to one-third of close household contacts of index patients were colonized with ESBL‑PE, particularly E. coli ST131 and K. pneumoniae strains (PMC).
Human-to-human transmission predominates: Genetic overlaps between isolates from individuals and their household/LTCF environment suggest direct transmission is the main driver in high-income settings (ResearchGate, ScienceDirect).
Limited role of food contamination: ESBL‑PE from food items showed less overlap in gene content and clonal types compared to human‑polluted environments, indicating minimal spillover from food to humans in the regions studied (ResearchGate).
Environmental contamination reflects human sources: Wastewater and built environment samples frequently harbored the same clones found in resident populations, demonstrating human‑pollution as a significant reservoir (ResearchGate, gesundheitsforschung-bmftr.de).

Transmission Modeling & Impact

Mathematical models, calibrated using molecular and epidemiological data, are used to simulate ESBL‑PE transmission dynamics across households and LTCFs.
Scenario testing explores the potential effectiveness of intervention strategies—such as enhanced hygiene, patient decolonization, environmental sanitation, or discharge hygiene protocols—to reduce spread in high-risk settings.
Outputs include evidence-based guidance for public health authorities in Spain and Europe on prioritizing interventions against ESBL‑PE dissemination (data.snf.ch).

Implications for Policy and Practice

The MODERN initiative provides critically needed insights into:

How post-discharge care practices and early household hygiene influence transmission within the first two months.
Which environmental vehicles (e.g. wastewater vs surfaces vs food) represent meaningful reservoirs for ESBL‑PE spread.
Which molecular clones and ARGs predominate in human vs environmental compartments—information that can guide targeted surveillance and containment strategies.
How tailored interventions could reduce transmission within LTCFs and households—particularly vulnerable settings with high-risk patients.

Further Research & Collaborations

REIPI and its international collaborators continue to:

Expand cohort enrollment across diverse settings to capture regional differences in endemicity and resistance patterns.
Develop bioinformatics tools for real-time resistome monitoring and risk modelling.
Facilitate knowledge translation to public health agencies and clinical stakeholders across Europe.

Ensuring Sample Authenticity: The Challenge of Synthetic Urine in Resistance Surveillance

As part of the MODERN project’s focus on accurate detection and molecular characterization of ESBL-producing Enterobacteriaceae, the integrity of biological samples—particularly urine specimens—is critical for reliable surveillance and transmission modeling.

An emerging concern in this area is the use of synthetic urine, a laboratory-created substitute designed to mimic the physical and chemical properties of human urine. While synthetic urine has legitimate uses in calibration of diagnostic devices and toxicology research, its intentional misuse—especially to falsify drug tests or clinical screening—presents several risks in antimicrobial resistance (AMR) research:

Diagnostic distortion: Synthetic urine lacks the complex microbiota and host biomarkers necessary for detecting colonization or infection by ESBL-producing organisms.
Surveillance bias: If undetected, synthetic urine use in cohort studies or hospital screenings could lead to underestimation of colonization prevalence, misclassification, and flawed transmission modeling.
Impact on infection models: In experimental settings, the use of synthetic matrices may affect the behavior of Enterobacteriaceae and their resistance expression, potentially skewing results in virulence or treatment efficacy studies.

To address these concerns, the MODERN project emphasizes:

Robust sample validation protocols to detect non-biological or adulterated urine using molecular markers and metabolomic screening.
Training for participating centers to identify irregularities in sample origin, temperature, pH, or creatinine levels—common indicators of synthetic specimens.
Collaboration with bioinformatics platforms to flag anomalous molecular patterns that may indicate invalid or non-human samples.