Serum amyloid A in monitoring clinical response to antimicrobial treatment

Utility of serum amyloid A in monitoring clinical response to antimicrobial treatment in horses with bacterial pneumonia

J Vet Intern Med. 2023 Jul 31.
Authors
Kate L Hepworth-Warren 1 , Krista Estell 2 , Bobby Cowles 3 , Deborah Amodie 3 , Mark Crisman 3
Affiliations

1 Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA.
2 Virginia Tech’s Marion duPont Scott Equine Medical Center, Leesburg, Virginia, USA.
3 Zoetis, Parsippany, New Jersey, USA.

PMID: 37522636
DOI: 10.1111/jvim.16818

Abstract

Background: Serum amyloid A (SAA) is a major acute phase protein in horses which could be a useful tool for assessing clinical response to treatment of bacterial pneumonia in adult horses.

Objectives: To monitor SAA concentration in response to treatment and identify associations among SAA concentration, WBC and neutrophil counts, and fibrinogen in bacterial pneumonia in adult horses.

Animals: Eighteen adult horses with bacterial pneumonia.

Methods: Prospective clinical study. Horses hospitalized with bacterial pneumonia were enrolled and SAA concentration and vital signs were assessed daily. SAA concentration was measured by a handheld meter. CBC and plasma fibrinogen were assessed on days 0, 1, and 2, then every 3 days until discharge. Data were not normally distributed and therefore were log transformed. Log-transformed data were analyzed and comparisons were performed on LSMeans by the 2-sided Student’s t-test at the 5% level of significance.

Results: Geometric mean SAA concentration on day 0 was 537 μg/mL (SE 383 μg/mL). Geometric mean SAA concentration decreased significantly over time (P = .0001), peaking at day 2 (geomean 1038 μg/mL, SE 261.7 μg/mL) and decreasing until discharge. Plasma concentration of fibrinogen (P = .06), neutrophil count (P = .48), and WBC count (P = .07) did not change significantly over time.

Conclusions and clinical importance: SAA concentration decreased significantly over the course of treatment and correlated with clinical improvement of pneumonia whereas fibrinogen, neutrophil, and WBC counts did not.

Keywords: acute phase; antimicrobials; equine; microbiology; pleuropneumonia; respiratory.

© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.