# Antimicrobial Resistant Isolates in Surgical and Bite Wounds in Dogs and Cats: A 12-Year Retrospective Analysis

## TL;DR

This study found high antibiotic resistance in surgical and bite wound infections in dogs and cats, emphasizing the need for careful antibiotic use in veterinary medicine.

## Contribution

The study provides a 12-year retrospective analysis of antimicrobial resistance in surgical and bite wound infections in companion animals in Italy.

## Key findings

- High resistance rates were observed for commonly prescribed antibiotics like amoxicillin–clavulanate and enrofloxacin.
- Resistance to last-resort antibiotics like carbapenems remained low, indicating their continued effectiveness.
- Methicillin resistance and ESBL-producing bacteria were identified in several isolates.

## Abstract

Antimicrobial resistance is one of the major health challenges of this century, affecting both animals and humans and making it a true One Health issue. Using antibiotics carefully and only when needed is essential to slow the spread of resistant bacteria and to preserve the effectiveness of these drugs. This study investigated antibiotic resistance in dogs and cats with infected surgical wounds or bite wounds—two of the most common reasons pets receive antibiotics—in a veterinary hospital located in northeastern Italy. The findings reveal a concerning situation: many of the antibiotics most frequently prescribed in small-animal practice showed high resistance rates, and a large proportion of treatments were empirical, meaning they were not guided by laboratory testing of bacterial susceptibility. Despite this, the data also highlighted an encouraging point: resistance to “last-resort” antibiotics remained low, suggesting that these critically important drugs are still effective when needed. Antibiotic resistance is now a widespread and growing problem worldwide. Responsible, well-targeted, and protocol-driven antimicrobial use is essential to limit its expansion, reduce the selective pressure that favors resistant bacteria, and protect the therapeutic value of antibiotics for both animals and humans.

Antimicrobial resistance (AMR) is an increasingly concern in both human and veterinary medicine, complicating the management of common clinical infections. Surgical site infections (SSIs) and bite wounds in pets are especially challenging due to their polymicrobial nature and multidrug-resistant strains. Laboratory records from a referral veterinary hospital in northwestern Italy were retrospectively analyzed. Bacterial cultures and antimicrobial susceptibility testing results from canine and feline surgical and bite wounds collected between 2013 and 2024 were reviewed. Data were analyzed descriptively to identify bacterial distribution and resistance trends. A total of 35 isolates (23 dogs; 12 cats) were obtained from 26 surgical and 9 bite wounds. In dogs, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus pseudintermedius were most frequently identified. In cats, Enterobacter cloacae, Escherichia coli, and Pasteurella multocida predominated. High resistance rates were recorded for amoxicillin–clavulanate, cephalexin, enrofloxacin, and marbofloxacin. Methicillin resistance emerged in most Staphylococcus aureus and several S. pseudintermedius isolates, while subsets of E. coli and K. pneumoniae were ESBL. Resistance to carbapenems remained low. Although samples were limited, these findings underscore the ongoing impact of AMR in surgical and bite wounds and highlight the importance of implementing rigorous antimicrobial stewardship practices in veterinary medicine.