Monitoring the Prevalence of Antimicrobial Resistance in Companion Animals: Results from Clinical Isolates in an Italian University Veterinary Hospital

The role of companion animals in the spread of antimicrobial resistance (AMR) is still not well known. As part of a wider surveillance system, this study aimed to provide data about AMR in bacterial isolates from infections in companion animals referred to an Italian University Veterinary Hospital (VUH) from November 2020 to September 2022. A total of 940 isolates were identified with MALDI-TOF MS and subsequently the antimicrobial susceptibility test (AST) for 12 antimicrobials was performed. Urine was the most commonly submitted specimen (54.92%) and Escherichia coli was the most common bacterial species isolated (36.06%). Out of the 940 isolates, 747 (79.47%) were nonsusceptible to at least one drug (AMR), while 420 (44.68%) were considered multidrug resistant (MDR). The highest nonsusceptibility percentages were recorded for clindamycin (59.65 %), erythromycin (58.96 %), ampicillin (52.85%), and enrofloxacin (48.19%). Alarming percentages were recorded also for ceftiofur (25.51%), amoxicillin–clavulanate (22.99%), and piperacillin–tazobactam (15.85%). In multivariable risk factors analysis, previous use of invasive devices ( in both cases) and previous use of antimicrobials ( in both cases) were statistically related with higher AMR and MDR percentages. Apart from a general evaluation, the study focused on specific bacterial species (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) and specimens (blood cultures, urine from suspected healthcare-associated urinary tract infections, and surgical site infections), showing in both cases higher AMR and MDR percentages compared to average. These data highlight the urgency to further investigate AMR spread in pets and how passive surveillance systems can be effective tools to monitor AMR and to optimize antimicrobial use.