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Journal of veterinary internal medicine2026; 40(3); aalag112; doi: 10.1093/jvimsj/aalag112

Retrospective study of blood culture isolates, antimicrobial sensitivity, and survival factors from 243 neonatal foals in Normandy (France).

Abstract: Identifying causative bacterial species in neonatal foal bacteremia and their antimicrobial susceptibility profiles is essential for guiding appropriate antibiotic therapy. Objective: To describe bacterial isolates from blood culture and their antimicrobial susceptibility patterns in neonatal foals from two French institutes, and to assess associations between pretreatment and blood culture positivity, and between in-hospital death (euthanasia or natural death) and the presence of multidrug-resistant (MDR) bacteria. Methods: Two hundred forty-three foals (<7 days old) admitted to two equine intensive care units in Normandy with blood cultures. Methods: Retrospective cohort study. Associations were assessed using chi-square test. Results: Blood cultures were positive in 43% of foals. Pretreatment was not significantly associated with blood culture positivity (P = .62). Gram-positive isolates predominated (65%). The most common isolates were Staphylococcus spp. (25%), Escherichia coli (11%), and Streptococcus spp. (11%). MDR bacteria represented 26% of isolates, predominantly Gram-positive. Low resistance to aminoglycosides, particularly amikacin (17%) and gentamicin (19%), was observed, whereas resistance to penicillin (53%) and ceftiofur (33%) was more common. Moderate resistance to tetracyclines (between 22% and 31%) was measured within overall bacteria. Similar resistance rates to trimethoprim-sulfamethoxazole and ceftiofur were observed among Gram-positive (≈ 35%) and Gram-negative isolates (26%). Presence (vs absence) of MDR isolates was not significantly associated with in-hospital death (P = .52). Conclusions: Consistent with recent reports, Gram-positive bacteria predominated among neonatal foal blood isolates in our sample. Despite its designation as a critically important human antibiotic, resistance to ceftiofur in our study necessitates utmost restraint in its use.
© The Author(s) 2026. Published by Oxford University Press on behalf of the American College of Veterinary Internal Medicine.
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Publication Date: 2026-06-17 PubMed ID: 42302765PubMed Central: PMC13271365DOI: 10.1093/jvimsj/aalag112Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study analyzed bacteria found in the blood of newborn foals in Normandy, France, focusing on which bacteria were present, how resistant they were to antibiotics, and whether these factors influenced survival.

Study Purpose and Importance

  • The research aimed to identify the specific bacteria causing bloodstream infections (bacteremia) in neonatal foals (under 7 days old).
  • Understanding bacterial species and their antibiotic resistance helps veterinarians choose appropriate treatments for sick foals.
  • The study also evaluated whether prior antibiotic treatment affected the likelihood of detecting bacteria in blood cultures and if infections with multidrug-resistant (MDR) bacteria influenced foal survival.

Methods

  • Data was collected retrospectively from 243 neonatal foals admitted to two equine intensive care units in Normandy, France.
  • Blood cultures were taken to detect the presence of bacteria in the bloodstream.
  • Statistical analyses, specifically chi-square tests, were used to explore associations between antibiotic pretreatment and culture positivity, as well as between MDR presence and in-hospital death.

Key Findings

  • Bacterial Culture Positivity: 43% of the foals had positive blood cultures indicating bacterial infection.
  • Pretreatment Impact: Prior antibiotic treatment did not significantly influence whether blood cultures were positive (P = 0.62).
  • Bacterial Types:
    • Gram-positive bacteria dominated, making up 65% of isolates.
    • The most frequent bacteria found were:
  • Antibiotic Resistance:
    • Multidrug-resistant (MDR) bacteria accounted for 26% of isolates, mostly Gram-positive.
    • Resistance rates were low for aminoglycosides like amikacin (17%) and gentamicin (19%).
    • Resistance was higher for penicillin (53%) and ceftiofur (33%).
    • Moderate resistance to tetracyclines was observed (22%-31%).
    • Similar resistance to trimethoprim-sulfamethoxazole and ceftiofur was seen in both Gram-positive (~35%) and Gram-negative bacteria (26%).
  • Survival Associations: Presence of MDR bacteria did not significantly associate with in-hospital death or euthanasia (P = 0.52).

Conclusions and Implications

  • This study confirmed that Gram-positive bacteria are the predominant cause of blood infections in neonatal foals in this region, consistent with recent trends.
  • Antibiotic resistance patterns raise concern, particularly the notable resistance to ceftiofur, a critically important antibiotic in human medicine, suggesting that its use in foals should be done with great caution.
  • The lack of association between MDR bacteria and survival indicates factors other than resistance may play significant roles in outcomes of bacteremia in neonatal foals.
  • Results highlight the importance of continuous monitoring of bacterial species and resistance patterns to guide effective and responsible antibiotic use in veterinary medicine.

Cite This Article

APA
Vigneau M, Picandet V, Polle F, Guérin V, Petry S, Desquilbet L, Quéré E. (2026). Retrospective study of blood culture isolates, antimicrobial sensitivity, and survival factors from 243 neonatal foals in Normandy (France). J Vet Intern Med, 40(3), aalag112. https://doi.org/10.1093/jvimsj/aalag112

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: England
Language: English
Volume: 40
Issue: 3
PII: aalag112

Researcher Affiliations

Vigneau, Marion
  • École Nationale Vétérinaire d'Alfort, Université Paris Est Créteil, INSERM, IMRB, Maisons-Alfort F-94700, France.
Picandet, Valérie
  • Centre Hospitalier Vétérinaire de Livet, Livarot-Pays-d'Auge F-14140, France.
Polle, Florence
  • Clinique Vétérinaire de Méheudin, Écouché-les-Vallées F-61150, France.
Guérin, Virginie
  • École Nationale Vétérinaire d'Alfort, Université Paris Est Créteil, INSERM, IMRB, Maisons-Alfort F-94700, France.
Petry, Sandrine
  • Physiopathology and Epidemiology of Equine Diseases Unit, ANSES Laboratory for Animal Health, Goustranville F-14430, France.
Desquilbet, Loic
  • École Nationale Vétérinaire d'Alfort, Université Paris Est Créteil, INSERM, IMRB, Maisons-Alfort F-94700, France.
Quéré, Emilie
  • École Nationale Vétérinaire d'Alfort, Université Paris Est Créteil, INSERM, IMRB, Maisons-Alfort F-94700, France.

MeSH Terms

  • Animals
  • Horses
  • Retrospective Studies
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Animals, Newborn
  • France / epidemiology
  • Horse Diseases / microbiology
  • Horse Diseases / mortality
  • Horse Diseases / drug therapy
  • Horse Diseases / blood
  • Female
  • Bacteremia / veterinary
  • Bacteremia / microbiology
  • Bacteremia / mortality
  • Bacteremia / drug therapy
  • Bacteremia / epidemiology
  • Microbial Sensitivity Tests / veterinary
  • Drug Resistance, Multiple, Bacterial
  • Male
  • Blood Culture / veterinary

Conflict of Interest Statement

Authors declare no conflicts of interest.

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