Sophie Haslam, Nicola Williams, Dorina Timofte, Gina Pinchbeck, Genever Morgan

University of Liverpool, Liverpool, United Kingdom

Objectives

To determine the presence of antimicrobial-resistant (AMR) Gram-negative ESKAPE organisms in commercially available raw and alternative pet diets in the UK.

Methods

A cross-sectional microbiological study was conducted on 55 alternative diets (13 brands; 22 freeze-dried, 15 cold-pressed, 10 gently cooked, 8 air-dried) and 100 raw diets (10 brands, 9–11 per brand). Samples were streaked onto selective media +/- cefotaxime (a third-generation cephalosporin (3GC)). MALDI-TOF mass spectrometry enabled species-level identification before antimicrobial susceptibility testing via disc diffusion. Antibiotics were chosen and breakpoints interpreted as per EUCAST guidelines and clinical breakpoints. Packaging was analysed for traceability information and evidence of leaks.

Results

Fifty-four (54/100; 54%) raw diet samples contained ≥1 3GC-resistant Gram-negative ESKAPE organism, comprising Acinetobacter spp. (28/100; 28%), Pseudomonas aeruginosa (24/100; 24%), and Enterobacter hormaechei (8/100; 8%).  One (1/55; 1.8%) alternative diet yielded 3GC-resistant Acinetobacter baumannii.  Phenotypic resistance was demonstrated to enrofloxacin, ampicillin, and amoxicillin-clavulanate. Packaging integrity and traceability issues were identified in both raw and alternative diets.

Statement: Impact/ Clinical Significance

The high prevalence of 3GC-resistant Gram-negative ESKAPE organisms in raw diets identifies them as a significant and under-recognised potential source of pathogenic and AMR bacteria for pets and humans. Notably, these organisms extend beyond those routinely screened for in commercial pet food testing and may have important clinical implications. They therefore pose a risk to pets, owners and veterinary staff, with potential for wider dissemination. Given the continued popularity of raw diets in the UK, these findings have One Health implications and highlight a need for improved regulation and owner awareness.