# Investigating Bacterial Bloodstream Infections in Dogs and Cats: A 4-Year Surveillance in an Italian Veterinary University Hospital

## TL;DR

A 4-year study in Italy found that bacterial bloodstream infections in dogs and cats are often caused by drug-resistant bacteria, stressing the need for better surveillance and targeted antibiotic use.

## Contribution

The study provides new insights into the prevalence of multidrug-resistant bacteria in veterinary bloodstream infections and their association with healthcare-associated risk factors.

## Key findings

- Escherichia coli was the most common bloodstream infection isolate in dogs and cats.
- Multidrug resistance was observed in 29.2% of cases, primarily among Gram-negative bacteria.
- Healthcare-associated infections were linked to invasive devices and were present in nearly half of the cases.

## Abstract

This 4-year prospective study investigated bacterial bloodstream infections (BSIs) in dogs and cats hospitalized at an Italian Veterinary University Hospital. From 96 positive blood cultures, Escherichia coli was the most common isolate, followed by Streptococcus canis. Multidrug resistance (MDR) was observed in 29.2% of cases, mainly among Gram-negative bacteria. Healthcare-associated infections were identified in 46.9% of cases, significantly linked to the use of invasive devices. Empirical antibiotic therapy was initiated in 94.8% of cases, achieving 76.9% in vitro appropriateness; in vitro inappropriate empirical treatment was correlated with MDR. Thirty-day mortality was 36.5%, significantly associated with antibiotic escalation. These findings emphasize the need for continuous blood culture surveillance, targeted antimicrobial stewardship, and infection control measures to optimize therapy and reduce MDR spread in veterinary practice.

In small animal practice, blood cultures (BCs) are essential for diagnosing bacterial bloodstream infections (BSIs) and guiding targeted antimicrobial therapy, particularly in relation to the rise of multidrug-resistant (MDR) pathogens. This study analyzed 96 positive BCs from dogs and cats at the Veterinary University Hospital (VUH) of Bologna (2020–2024), assessing bacterial prevalence, antimicrobial resistance, and associated risk factors. Escherichia coli was the most common isolate (29/96), followed by Streptococcus canis (11/96). MDR percentage was 29.2% (28/96), with Gram-negatives associated with higher rates (p = 0.040). Nearly half of the cases (46.9%, 45/96) were suspected healthcare-associated infections (HAIs) significantly associated with the number of invasive devices used (p = 0.008) and with the absence of co-positive samples (p = 0.012). Empirical antibiotic therapy was administered in 94.8% (91/96) of cases, with ampicillin–sulbactam and marbofloxacin as the most used drugs. In vitro empirical therapy appropriateness was 76.9% (70/91). MDR was associated with inappropriate empirical therapy (p < 0.001). Mortality within 30 days was 36.5% (35/96), significantly linked to antibiotic escalation (p = 0.006). The findings highlight the need for systematic BC surveillance in veterinary settings to optimize treatment strategies (especially in countries with restrictions on antibiotic use in animals) to mitigate MDR spread and to protect public health.