D_6_(-)2.itmx3D OrbiSIMS Metabolic Profiling of E. coli Reveals Effects of FMT- Derived Faecal Filtrate and Phage-Azithromycin on Amino Acids and Lipid Pathways.

Antimicrobial resistance (AMR) represents a pressing global health threat, necessitating innovative alternatives to traditional antibiotics. Among these, bacteriophage therapy and faecal microbiota transplantation (FMT)-based interventions have emerged as promising strategies. However, the metabolic responses of multidrug-resistant (MDR) pathogens to these therapies remain poorly understood. In this study, we applied advanced 3D Orbitrap Secondary Ion Mass Spectrometry (3D OrbiSIMS) metabolomics, offering ultra-high mass resolution (>240,000) and sub-2 ppm mass accuracy, to profile metabolic alterations in pathogenic Escherichia coli strains, Enteroaggregative (EAEC) and Enteroinvasive (EIEC), following treatment with lytic phage vB_EcoM_SVMS_56, phage–azithromycin combination therapy, and sterile faecal filtrates from healthy FMT donors (n = 4; mean age 33.75 ± 2.38 years).