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Journal of veterinary internal medicine2019; 34(1); 300-306; doi: 10.1111/jvim.15685

Antimicrobial susceptibility of bacterial isolates from ambulatory practice and from a referral hospital.

Abstract: Responsible use of antimicrobials in equine practice relies on knowledge of common bacterial isolates and their antimicrobial sensitivities. Objective: To assess the frequency of bacterial resistance to a combination of parenteral penicillin and gentamicin and to trimethoprim and sulfamethoxazole for PO use in a selection of clinical isolates, and subsequently to determine the prevalence of resistance to antimicrobials that might then be used as alternatives to first-line antimicrobials for the same isolates. Methods: Retrospective analysis of minimal inhibitory concentrations (MICs) of antimicrobials for 6354 bacterial isolates from 365 ambulatory practices and 519 isolates from a referral hospital. The MICs were used to indicate sensitivity or resistance to commonly used antimicrobials and the prevalences of resistance were compared between origin of the isolates, and among antimicrobial drugs. Results: Isolates from the referral hospital were significantly (P < .05) more likely to be resistant to the antimicrobials tested than those derived from ambulatory practice. Overall, 91% of the ambulatory isolates and 64% of the hospital isolates were sensitive to penicillin-gentamicin. For trimethoprim-sulfamethoxazole combination, 82% of the ambulatory practice isolates and 56% of the referral hospital isolates were sensitive. Conclusions: Most isolates were sensitive to penicillin and gentamicin as well as trimethoprim-sulfamethoxazole. No predictable efficacious second choice antimicrobial was identified for those isolates resistant to the first-line antimicrobials. The likelihood of isolates being sensitive to second choice antimicrobials was variable but generally higher for ambulatory isolates compared to referral isolates. Bacterial identification and measurement of MIC are essential to make the appropriate antimicrobial choice.
© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
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Publication Date: 2019-12-17 PubMed ID: 31849110PubMed Central: PMC6979268DOI: 10.1111/jvim.15685Google 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.

The research article discusses the evaluation of bacterial resistance to common antimicrobial drugs used in equine practice. It found that a majority of bacterial isolates were sensitive to the primary antimicrobial, with a higher resistance observed in organisms originating from a referral hospital compared to those from ambulatory practices.

Objective and Methodology

  • The primary purpose of the study was to assess the resistance of common bacterial isolates to popular antimicrobials used in equine care, thereby informing sound antimicrobial utilization.
  • It aimed to gauge the effectiveness of combination drugs such as parenteral penicillin and gentamicin, and trimethoprim with sulfamethoxazole. It also sought to determine suitable alternative antimicrobials in case of resistance to the first-line drugs.
  • The investigation executed a retrospective analysis of antimicrobial minimal inhibitory concentrations (MICs) for bacterial isolates measures the amount of an antimicrobial substance that inhibits growth of these organisms.
  • A vast range of isolates were tested – 6354 from 365 ambulatory practices and 519 from a referral hospital. These MIC figures were then deployed to deduce resistance or sensitivity to the drugs in question.

    Results

    • The study discovered that isolates originating from the referral hospital were noticeably more resistant to the tested antimicrobials than those from ambulatory practices, with the difference in resistance levels being statistically significant.
    • In terms of sensitivity to the penicillin-gentamicin combo, about 91% of the isolates from ambulatory practices and 64% from the hospital showed a positive response.
    • When switching to the use of trimethoprim with sulfamethoxazole, the sensitivity rates stood at 82% (ambulatory practices) and 56% (referrals).

      Conclusions

      • The authors found most of the bacterial isolates to be sensitive to primary antimicrobials i.e. penicillin and gentamicin, and trimethoprim-sulfamethoxazole.
      • However, they were unable to identify a consistently effective second-choice antimicrobial for those isolates that proved resistant to first-line antimicrobials.
      • The prospect of isolate sensitivity to secondary antimicrobials was found to be variable, with a typically higher likelihood in ambulatory specimens than referral specimens.
      • The research underlines the critical importance of bacterial identification and accurate MIC measurement for making the most suitable choice of antimicrobial.

Cite This Article

APA
Potier JFN, Durham AE. (2019). Antimicrobial susceptibility of bacterial isolates from ambulatory practice and from a referral hospital. J Vet Intern Med, 34(1), 300-306. https://doi.org/10.1111/jvim.15685

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 34
Issue: 1
Pages: 300-306

Researcher Affiliations

Potier, Julie F N
  • The Liphook Equine Hospital, Hampshire, United Kingdom.
Durham, Andy E
  • The Liphook Equine Hospital, Hampshire, United Kingdom.

MeSH Terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Bacteria / drug effects
  • Drug Resistance, Bacterial
  • Hospitals, Animal
  • Retrospective Studies

Conflict of Interest Statement

Authors declare no conflict of interest.

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Citations

This article has been cited 2 times.
  1. Garland A, van Doorn DA, van den Boom R, Roelfsema E, Jung L, Boast M, Papadakis K, Margiotta M, Wafelbakker S, Briggs M, McCrae P, Pearson W. Morphometric changes in overweight horses following 10-week weight loss programs. BMC Vet Res 2025 Oct 10;21(1):596.
    doi: 10.1186/s12917-025-05032-zpubmed: 41068901google scholar: lookup
  2. Hallowell KL, Hepworth-Warren KL, Dembek K. An updated description of bacterial pneumonia in adult horses and factors associated with death. J Vet Intern Med 2024 Sep-Oct;38(5):2766-2775.
    doi: 10.1111/jvim.17141pubmed: 39005215google scholar: lookup
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