# Veterinary blood culture diagnostic testing: methodology and results from a German single-center study on dogs (2014-2022)

## TL;DR

This study analyzed blood culture results in dogs at a German hospital from 2014 to 2022, finding a 13.6% yield of clinically relevant bacteria and highlighting factors affecting diagnostic accuracy.

## Contribution

The study identifies management factors affecting blood culture yield and contamination in veterinary medicine, emphasizing antimicrobial resistance and processing delays.

## Key findings

- Blood culture yield was 13.6% with a contamination rate of 1.9%.
- Multidrug-resistant and methicillin-resistant bacteria were frequently isolated.
- Antimicrobial pretreatment increased the likelihood of multidrug-resistant isolates.

## Abstract

Blood cultures (BCs) are the gold standard for identifying bacterial bloodstream infections and are vital for directing antimicrobial treatment.

Characterize BC results and diagnostic testing in veterinary medicine. Pathogen identification (ID) results, antimicrobial susceptibility testing (AST) results, and management factors were investigated to identify optimization opportunities.

A total of 750 BCs from 687 dogs presented between January 2014 and September 2022 at a German teaching hospital, with 102 positive BCs from 101 dogs.

Retrospective analysis of historical data. A BC system suitable for aerobic and anaerobic pathogens was used.

Blood culture yield (clinically relevant growth in 102/750 BCs) was 13.6%, and the contamination rate was 1.9%. Commonly isolated pathogens were Enterobacterales (n = 15/25 multidrug-resistant), coagulase-positive staphylococci (n = 3/23 methicillin-resistant), beta-hemolytic streptococci (n = 19), and obligate anaerobes (n = 22). Polymicrobial growth occurred in 8 BCs (7.8%). Median duration of the preanalytical phase (sampling until receipt in laboratory) was 1 day (interquartile range [IQR], 1-2), from receipt in laboratory until ID results 1 day (IQR, 1-2), and until AST results 2 days (IQR, 2-4). The preanalytical phase of BCs taken on weekends was a median of 1 day longer (P < .001). Dogs treated with antimicrobials within 7 days before sampling were 10.74 times more likely to yield a multidrug-resistant isolate (95% confidence interval [CI], 3.62-31.86).

Improving BC processing requires addressing the management factors BC yield, contamination rate, weekend sampling, and antimicrobial pretreatment. Detection of resistant bacteria emphasizes the need for more rapid processing to shorten the time to optimized antimicrobial treatment.