AUTHOR=Eddoubaji Yasmine , Aldeia Claudia , Campos-Madueno Edgar I. , Moser Aline I. , Kundlacz Cindy , Perreten Vincent , Hilty Markus , Endimiani Andrea 

TITLE=A new in vivo model of intestinal colonization using Zophobas morio larvae: testing hyperepidemic ESBL- and carbapenemase-producing Escherichia coli clones

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1381051

DOI=10.3389/fmicb.2024.1381051

ISSN=1664-302X

ABSTRACT=<p>Finding strategies for decolonizing gut carriers of multidrug-resistant <italic>Escherichia coli</italic> (MDR-<italic>Ec</italic>) is a public-health priority. In this context, novel approaches should be validated in preclinical <italic>in vivo</italic> gut colonization models before being translated to humans. However, the use of mice presents limitations. Here, we used for the first time <italic>Zophobas morio</italic> larvae to design a new model of intestinal colonization (28-days duration, T28). Three hyperepidemic MDR-<italic>Ec</italic> producing extended-spectrum β-lactamases (ESBLs) or carbapenemases were administered via contaminated food to larvae for the first 7 days (T7): <italic>Ec</italic>-4901.28 (ST131, CTX-M-15), <italic>Ec</italic>-042 (ST410, OXA-181) and <italic>Ec</italic>-050 (ST167, NDM-5). Growth curve analyses showed that larvae became rapidly colonized with all strains (T7, ~10<sup>6–7</sup> CFU/mL), but bacterial load remained high after the removal of contaminated food only in <italic>Ec</italic>-4901.28 and <italic>Ec</italic>-042 (T28, ~10<sup>3–4</sup> CFU/mL). Moreover, larvae receiving a force-feeding treatment with <italic>INTESTI bacteriophage</italic> cocktail (on T7 and T10 via gauge needle) were decolonized by <italic>Ec</italic>-4901.28 (<italic>INTESTI</italic>-susceptible); however, <italic>Ec</italic>-042 and <italic>Ec</italic>-050 (<italic>INTESTI</italic>-resistant) did not. Initial microbiota (before administering contaminated food) was very rich of bacterial genera (e.g., <italic>Lactococcus</italic>, <italic>Enterococcus, Spiroplasma</italic>), but patterns were heterogeneous (Shannon diversity index: range 1.1–2.7) and diverse to each other (Bray–Curtis dissimilarity index ≥30%). However, when larvae were challenged with the MDR-<italic>Ec</italic> with or without administering bacteriophages the microbiota showed a non-significant reduction of the diversity during the 28-day experiments. In conclusion, the <italic>Z. morio</italic> larvae model promises to be a feasible and high-throughput approach to study novel gut decolonization strategies for MDR-<italic>Ec</italic> reducing the number of subsequent confirmatory mammalian experiments.</p>