Use of Liposomal Gentamicin for Treatment of 5 Foals with Experimentally Induced Rhodococcus equi Pneumonia.
Abstract: Adverse effects of, and bacterial resistance to, macrolides used to treat Rhodococcus equi infections have prompted search for clinically effective alternative antimicrobials. Liposomal gentamicin (LG) is effective against R. equi in vitro and decreases tissue concentrations of R. equi in experimentally infected mice. Effectiveness of LG treatment of foals with R. equi pneumonia, however, has not been described. Objective: Liposomal gentamicin is safe and effective for treating foals with R. equi pneumonia. Methods: Ten foals with experimentally induced R. equi pneumonia. Methods: Pilot treatment trial. Foals with pneumonia induced by intrabronchial instillation of R. equi were randomly allocated to receive either clarithromycin combined with rifampin (CLR + RIF) PO or LG IV, and followed by daily physical examinations and weekly thoracic ultrasonography and serum creatinine concentration determinations until the resolution of clinical signs. Treatment success was defined as the resolution of clinical signs and ultrasonographically identified pulmonary abscesses. Results: All 10 foals were successfully treated. Two of 5 foals treated with LG developed azotemia within 1 week; LG was discontinued and treatment switched to CLR + RIF for these foals. None of the CLR + RIF treated foals developed azotemia. Conclusions: Liposomal gentamicin IV can be effective for treatment of R. equi pneumonia, but nephrotoxicity indicates that an alternative dosing interval or route (such as nebulization) will be needed before LG is adequately safe for clinical use. Larger comparative trials will be needed to evaluate the relative efficacy of a safer LG dosage regimen.
Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
Publication Date: 2015-12-22 PubMed ID: 26692327PubMed Central: PMC4913631DOI: 10.1111/jvim.13810Google Scholar: Lookup
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- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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This research examines the effectiveness of a drug called Liposomal Gentamicin in treating pneumonia in foals caused by Rhodococcus equi bacteria. The study found the treatment successful but highlighted a problem with potential kidney toxicity (nephrotoxicity), suggesting that further research is needed to find a safer dosage or delivery method for the drug.
Objective and Methods
- The researchers aimed to explore the potency of Liposomal Gentamicin (LG), an alternative antimicrobial treatment for R. equi pneumonia in foals. The traditional treatments, macrolides, have found issues with bacterial resistance and adverse side effects.
- The study involved ten foals with pneumonia induced deliberately for the sake of the research. The pneumonia was caused through an intrabronchial instillation of R. equi bacteria.
- The foals were randomly assigned to one of two treatment groups: one received an oral dosage of clarithromycin combined with rifampin (CLR + RIF), while the other was treated with intravenous LG.
- The condition of the foals was monitored by daily physical exams, weekly thoracic ultrasonography, and serum creatinine concentration determinations until all clinical symptoms had resolved.
- Success in treatment was defined as the complete resolution of clinical signs and the disappearance of pulmonary abscesses identifiable by ultrasonography.
Results
- The study found that all ten foals recovered from their R. equi pneumonia after treatment.
- However, two of the five foals who received the LG treatment developed azotemia (excess of nitrogen compounds in the blood) within a week. These two were subsequently switched to the CLR + RIF treatment.
- None of the foals that received the CLR + RIF treatment developed azotemia.
Conclusions and Future Directions
- The study concluded that intravenous liposomal gentamicin can be effective in treating R. equi pneumonia in foals.
- However, the development of azotemia in two of the LG-treated foals points to potential nephrotoxicity. This suggests that an alternative dosing schedule or administration route (such as nebulization) may be needed to ensure the safe use of this drug.
- The researchers recommend larger, comparative trials to evaluate the relative effectiveness of a safer LG dosage regimen.
Cite This Article
APA
Cohen ND, Giguère S, Burton AJ, Rocha JN, Berghaus LJ, Brake CN, Bordin AI, Coleman MC.
(2015).
Use of Liposomal Gentamicin for Treatment of 5 Foals with Experimentally Induced Rhodococcus equi Pneumonia.
J Vet Intern Med, 30(1), 322-325.
https://doi.org/10.1111/jvim.13810 Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA.
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA.
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA.
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
MeSH Terms
- Actinomycetales Infections / microbiology
- Actinomycetales Infections / veterinary
- Animals
- Anti-Bacterial Agents / administration & dosage
- Anti-Bacterial Agents / therapeutic use
- Clarithromycin / administration & dosage
- Clarithromycin / therapeutic use
- Gentamicins / administration & dosage
- Gentamicins / therapeutic use
- Horse Diseases / drug therapy
- Horse Diseases / microbiology
- Horses
- Liposomes
- Rhodococcus equi
- Rifampin / administration & dosage
- Rifampin / therapeutic use
References
This article includes 10 references
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- Giguѐre S, Jordan LM, Glass K, Cohen ND. Relationship of mixed bacterial infection to prognosis in foals with pneumonia caused by Rhodococcus equi. J Vet Intern Med 2012;26:1443–1448.
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- Swenson CE, Stewart KA, Hammett JL. Pharmacokinetics and in vivo activity of liposome‐encapsulated gentamicin.. Antimicrob Agents Chemother 1990;34:235–240.
- Klemens SP, Cynamon MH, Swenson CE, Ginsberg RS. Liposome‐encapsulated‐gentamicin therapy of Mycobacterium avium complex infection in beige mice.. Antimicrob Agents Chemother 1990;34:967–970.
- Burton AJ, Giguère S, Arnold RD. Pharmacokinetics, pulmonary disposition and tolerability of liposomal gentamicin and free gentamicin in foals.. Equine Vet J 2015;47:467–472.
- Burton AJ, Giguère S, Berghaus LJ. Efficacy of liposomal gentamicin against Rhodococcus equi in a mouse infection model and colocalization with R. equi in equine alveolar macrophages.. Vet Microbiol 2015;176:292–300.
- Hildebrand F, Venner M, Giguère S. Efficacy of gamithromycin for the treatment of foals with mild to moderate bronchopneumonia.. J Vet Intern Med 2015;29:333–338.
Citations
This article has been cited 3 times.- Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
- Rakowska A, Cywinska A, Witkowski L. Current Trends in Understanding and Managing Equine Rhodococcosis. Animals (Basel) 2020 Oct 18;10(10).
- Mourenza Á, Gil JA, Mateos LM, Letek M. A Novel Screening Strategy Reveals ROS-Generating Antimicrobials That Act Synergistically against the Intracellular Veterinary Pathogen Rhodococcus equi. Antioxidants (Basel) 2020 Jan 28;9(2).
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