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Bond S, Léguillette R. A CONSORT-guided, randomized controlled clinical trial of nebulized administration of dexamethasone and saline on lower airway cytokine mRNA expression in horses with moderate asthma. J Vet Intern Med 2024; 38:1214-1223. [PMID: 38205666 PMCID: PMC10937472 DOI: 10.1111/jvim.16983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
BACKGROUND Nebulized administration of dexamethasone on cytokine regulation in horses with moderate asthma has not been investigated. OBJECTIVE To investigate the changes in expression of inflammatory cytokine mRNA after nebulized administration of dexamethasone treatment of horses with moderate asthma. ANIMALS Horses with naturally occurring moderate asthma (n = 16) and healthy control horses (n = 4). All horses were kept in a dusty environment during the study. METHODS Prospective, parallel, randomized, controlled, blinded clinical trial. Blood endogenous cortisol, tracheal mucus, and bronchoalveolar lavage (BAL) were sampled before and after 13 days treatment with either nebulized administration of dexamethasone (15 mg once daily) or 0.9% saline (3 mL). Treatment groups were randomly allocated via randomization function (Microsoft Excel). Amplification of target mRNA in BAL fluid (IL-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-17, IL-23, IFN-γ, Eotaxin-2, and TNF-α) was achieved by qPCR, and the relative expression software tool was used to analyze BAL inflammatory cytokine mRNA. RESULTS Horses treated with nebulized administration of dexamethasone had increased relative expression of IL-5 (1.70-fold), IL-6 (1.71-fold), IL-17 (3.25-fold), IL-12 (1.66-fold), and TNF-α (1.94-fold), and decreased relative expression of IL-23 (1.76-fold; P = .04) in samples collected on Day 14, in comparison to samples collected on Day 0 (all P < .05). Horses treated with nebulized administration of saline had no significant difference in the relative expression of any gene (all P > .05). CONCLUSIONS AND CLINICAL IMPORTANCE Nebulized administration of dexamethasone was associated with increased expression of inflammatory cytokine mRNA. There was no improvement in inflammatory airway cytology associated with either dexamethasone or saline treatment.
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Affiliation(s)
- Stephanie Bond
- Faculty of Veterinary MedicineUniversity of CalgaryCalgaryAlbertaCanada
- School of Veterinary Science, Faculty of ScienceUniversity of QueenslandGattonQueenslandAustralia
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Swink JM, Rings LM, Snyder HA, McAuley RC, Burns TA, Dembek KA, Gilsenan WF, Browne N, Toribio RE. Dynamics of androgens in healthy and hospitalized newborn foals. J Vet Intern Med 2020; 35:538-549. [PMID: 33277956 PMCID: PMC7848305 DOI: 10.1111/jvim.15974] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 01/25/2023] Open
Abstract
Background Information on steroids derived from the adrenal glands, gonads, or fetoplacental unit is minimal in newborn foals. Objective To measure androgen concentrations in serum and determine their association with disease severity and outcome in hospitalized foals. Animals Hospitalized (n = 145) and healthy (n = 80) foals. Methods Prospective, multicenter, cross‐sectional study. Foals of ≤3 days of age from 3 hospitals and horse farms were classified as healthy and hospitalized (septic, sick nonseptic, neonatal maladjustment syndrome [NMS]) based on physical exam, medical history, and laboratory findings. Serum androgen and plasma ACTH concentrations were measured with immunoassays. Data were analyzed by nonparametric methods and univariate analysis. Results Serum dehydroepiandrosterone (DHEA), androstenedione, testosterone, and dihydrotestosterone (DHT) concentrations were higher upon admission in hospitalized foals (P < .05), were associated with nonsurvival, decreased to 4.9‐10.8%, 5.7‐31%, and 30.8‐62.8% admission values in healthy, SNS, and septic foals, respectively (P < .05), but remained unchanged or increased in nonsurviving foals. ACTH:androgen ratios were higher in septic and NMS foals (P < .05). Foals with decreased androgen clearance were more likely to die (odds ratio > 3; P < .05). Conclusions and Clinical Importance Similar to glucocorticoids, mineralocorticoids, and progestagens, increased serum concentrations of androgens are associated with disease severity and adverse outcome in hospitalized newborn foals. In healthy foals, androgens decrease over time, however, remain elevated longer in septic and nonsurviving foals. Androgens could play a role in or reflect a response to disorders such as sepsis or NMS in newborn foals.
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Affiliation(s)
- Jacob M Swink
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Lindsey M Rings
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA.,Rood and Riddle Equine Hospital, Lexington, Kentucky, USA
| | - Hailey A Snyder
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Rachel C McAuley
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Teresa A Burns
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Katarzyna A Dembek
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | | | - Nimet Browne
- Hagyard Equine Medical Institute, Lexington, Kentucky, USA
| | - Ramiro E Toribio
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
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Sierra-Rodriguez T, Groover ES, Lascola KM, Mora-Pereira M, Lee YH, Duran SH, Ravis WR, Spangler E, Hathcock T, Wooldridge AA. Clinical Feasibility and Airway Deposition of Nebulized Voriconazole in Healthy Horses. J Equine Vet Sci 2020; 94:103246. [PMID: 33077094 DOI: 10.1016/j.jevs.2020.103246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/05/2020] [Accepted: 08/24/2020] [Indexed: 10/23/2022]
Abstract
Voriconazole (VRC) is a potential treatment for pneumomycosis in horses. The objectives of this study were to determine if the delivery of Vfend using a Flexineb nebulizer produced clinically significant [VRC] in lower airways. The hypothesis was that [VRC] after delivery by nebulization would be greater in the pulmonary epithelial lining fluid than plasma. A secondary objective was to determine [VRC] in upper airways through the collection of nasopharyngeal wash (NPW) samples. Voriconazole solution [Vfend-6.25 mg/mL, 100 (n = 2), 200 (n = 3), 500 (n = 1) mg] was nebulized once in 6 healthy geldings. Clinical responses, duration of nebulization, and [VRC] at various time points (up to 8 hours) in plasma, bronchoalveolar lavage fluid (BALF) supernatant and cell pellet, and NPW samples were recorded. Voriconazole (Vfend-6.25 mg/mL, 200 mg) was nebulized in 5 additional, healthy geldings, and [VRC] was measured in NPW samples pre- and postnebulization at time points up to 8 hours. The antifungal activity of BALF and NPW samples was determined using agar disk diffusion. Concentrations of voriconazole were below detection in plasma, BALF supernatant, and cell pellets for all time points and doses except the BALF cell pellet (0.4 μg/g) immediately after nebulization of 500 mg. For 5 horses, administered 200 mg of Vfend, mean [VCR] in NPW at the end of nebulization and 1, 6, and 8 hours postnebulization were: 30.8 ± 29, 1.0 ± 0.84, 0.2 ± 0.19, and 0.34 ± 0.67 μg/mL, respectively. Only NPW samples obtained immediately postnebulization showed antifungal activity. A nebulized Vfend solution is not recommended for the treatment of pneumomycosis in horses.
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Affiliation(s)
- Tamara Sierra-Rodriguez
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Erin S Groover
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Kara M Lascola
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Mariano Mora-Pereira
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Yann H Lee
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL
| | - Sue H Duran
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - William R Ravis
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL
| | - Elizabeth Spangler
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Terri Hathcock
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL
| | - Anne A Wooldridge
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL.
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Abstract
The management of difficult-to-treat acute and chronic respiratory infections (infections in cystic fibrosis, non-cystic fibrosis bronchiectasis, immunocompromised and mechanically ventilated patients) and difficult-to-treat pathogens (including multidrug-resistant strains) has become a challenge in clinical practice. The arsenal of conventional antibiotic drugs can be limited by tissue penetration, toxicities, or increasing antibiotic resistance. Inhaled antimicrobials are an interesting therapeutic approach for optimizing the management of respiratory infections. Due to extensive developments in liposome technology, a number of inhaled liposome-based antibiotic and antifungal formulations are available for human use and many products are undergoing clinical trials. Liposomes are biocompatible, biodegradable, and nontoxic vesicles able to encapsulate and carry antimicrobials, enhancing the therapeutic index of various agents and retention at the desired target within the lung. Liposomes reduce drug toxicity and improve tolerability, leading to better compliance and to decreased respiratory side effects. The aim of this article was to provide an up-to-date overview of nebulized liposomal antimicrobials for lung infections (with a special focus on liposomal amikacin, tobramycin, ciprofloxacin, and amphotericin B for inhalation), discussing the feasibility and therapeutic potential of these new strategies of preventing and treating bacteria, mycobacterial and fungal infections.
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Affiliation(s)
- Matteo Bassetti
- Infectious Diseases Unit, Ospedale Policlinico San Martino, IRCCS, Genoa, Italy.
- Department of Health Sciences, University of Genoa, Genoa, Italy.
| | - Antonio Vena
- Infectious Diseases Unit, Ospedale Policlinico San Martino, IRCCS, Genoa, Italy
| | - Alessandro Russo
- Division of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Maddalena Peghin
- Infectious Diseases Clinic, Department of Medicine, University of Udine and Azienda Sanitaria Universitaria Integrata, Udine, Italy
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Morgane Canonne A, Roels E, Menard M, Desquilbet L, Billen F, Clercx C. Clinical response to 2 protocols of aerosolized gentamicin in 46 dogs with Bordetella bronchiseptica infection (2012-2018). J Vet Intern Med 2020; 34:2078-2085. [PMID: 32790103 PMCID: PMC7517846 DOI: 10.1111/jvim.15843] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/13/2020] [Accepted: 06/13/2020] [Indexed: 11/30/2022] Open
Abstract
Background Bordetella bronchiseptica (Bb) infection commonly causes respiratory disease in dogs. Gentamicin delivered by aerosol maximizes local drug delivery without systemic absorption but clinical response to protocols remains undetermined. Objectives To compare the clinical response to 2 protocols of aerosolized delivery of gentamicin in bordetellosis. Animals Forty‐six dogs with Bb infection confirmed by culture or quantitative polymerase chain reaction on bronchoalveolar lavage. Methods Retrospective study. Administration of aerosolized gentamicin for ≥10 minutes q12h for ≥3 weeks using 4 mg/kg diluted with saline (group 1) or undiluted 5% solution (group 2). Clinical response firstly assessed after 3‐4 weeks and treatment pursued by 3‐weeks increments if cure not reached. Cure defined as absence of cough persisting at least a week after treatment interruption. Results Demographic data were similar between both groups. Clinical cure at 3‐4 weeks was more frequently observed with the use of undiluted solution (19/33 vs 3/13 dogs, P = .03) in association with a shorter median duration of treatment (4 vs 6 weeks, P = .01). Dogs from group 2 having less than 1000 cells/μL in lavage were also more likely to be cured at 3‐4 weeks than dogs with more than 1000 cells/μL [9/9 vs 10/19, P = .006] and median duration of treatment in that subgroup of animals was reduced (3 vs 5 weeks, P = .02). Conclusion and Clinical Importance Aerosolized delivery of gentamicin seems effective for inducing clinical cure in Bb infection. Clinical response appears better using undiluted 5% solution, particularly in the subgroup of dogs having less than 1000 cells/μL in lavage.
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Affiliation(s)
- Aude Morgane Canonne
- Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, Liège, Belgium.,Small Animals Internal Medicine Unit, National Veterinary School of Alfort, Maisons-Alfort, France
| | - Elodie Roels
- Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
| | - Maud Menard
- Small Animals Internal Medicine Unit, National Veterinary School of Alfort, Maisons-Alfort, France
| | - Loïc Desquilbet
- Unit of Biostatistics, National Veterinary School of Alfort, Maisons-Alfort, France
| | - Frédéric Billen
- Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
| | - Cécile Clercx
- Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
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Haspel AD, Giguère S, Hart KA, Berghaus LJ, Davis JL. Bioavailability and tolerability of nebulised dexamethasone sodium phosphate in adult horses. Equine Vet J 2017; 50:85-90. [PMID: 28719014 DOI: 10.1111/evj.12724] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022]
Abstract
BACKGROUND Nebulisation of the injectable dexamethasone sodium phosphate (DSP) would offer an inexpensive way of delivering a potent corticosteroid directly to the lungs of horses with asthma. However, this approach would be advantageous only if systemic absorption is minimal and if the preservatives present in the formulation do not induce airway inflammation. OBJECTIVE To investigate the bioavailability of nebulised DSP and determine whether it induces airway inflammation or hypothalamic-pituitary-adrenal (HPA) axis suppression in healthy adult horses. STUDY DESIGN Randomised crossover experiment. METHODS Dexamethasone sodium phosphate was administered to six healthy adult horses at a dose of 5 mg q. 24 h for 5 days via nebulised, or intravenous (i.v.) routes. Plasma dexamethasone concentrations were measured by UPLC/MS-MS to calculate bioavailability. Cytological examination of bronchoalveolar fluid was performed at baseline and after the last dose of DSP. A validated chemiluminescent immunoassay was used to measure basal serum cortisol concentrations. RESULTS After nebulisation to adult horses, dexamethasone had a mean (±s.d.) maximum plasma concentration of 0.774 ± 0.215 ng/mL and systemic bioavailability of 4.3 ± 1.2%. Regardless of route of administration, there was a significant decrease in the percentage of neutrophils in bronchoalveolar lavage fluid over time. During i.v. administration, basal serum cortisol concentration decreased significantly from baseline to Day 3 and remained low on Day 5. In contrast, basal serum cortisol concentration did not change significantly during administration via nebulisation. MAIN LIMITATIONS Small sample size and short period of drug administration. CONCLUSIONS Dexamethasone sodium phosphate administered via nebulisation had minimal systemic bioavailability and did not induce lower airway inflammation or HPA axis suppression in healthy horses.
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Affiliation(s)
- A D Haspel
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - S Giguère
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - K A Hart
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - L J Berghaus
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - J L Davis
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Blacksburg, Virginia, USA
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7
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Magdesian KG. Antimicrobial Pharmacology for the Neonatal Foal. Vet Clin North Am Equine Pract 2017; 33:47-65. [DOI: 10.1016/j.cveq.2016.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Giguère S. Treatment of Infections Caused by Rhodococcus equi. Vet Clin North Am Equine Pract 2017; 33:67-85. [DOI: 10.1016/j.cveq.2016.11.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Rocha JN, Cohen ND, Bordin AI, Brake CN, Giguère S, Coleman MC, Alaniz RC, Lawhon SD, Mwangi W, Pillai SD. Oral Administration of Electron-Beam Inactivated Rhodococcus equi Failed to Protect Foals against Intrabronchial Infection with Live, Virulent R. equi. PLoS One 2016; 11:e0148111. [PMID: 26828865 PMCID: PMC4735123 DOI: 10.1371/journal.pone.0148111] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 01/13/2016] [Indexed: 02/07/2023] Open
Abstract
There is currently no licensed vaccine that protects foals against Rhodococcus equi–induced pneumonia. Oral administration of live, virulent R. equi to neonatal foals has been demonstrated to protect against subsequent intrabronchial challenge with virulent R. equi. Electron beam (eBeam)-inactivated R. equi are structurally intact and have been demonstrated to be immunogenic when administered orally to neonatal foals. Thus, we investigated whether eBeam inactivated R. equi could protect foals against developing pneumonia after experimental infection with live, virulent R. equi. Foals (n = 8) were vaccinated by gavaging with eBeam-inactivated R. equi at ages 2, 7, and 14 days, or gavaged with equal volume of saline solution (n = 4), and subsequently infected intrabronchially with live, virulent R. equi at age 21 days. The proportion of vaccinated foals that developed pneumonia following challenge was similar among the vaccinated (7/8; 88%) and unvaccinated foals (3/4; 75%). This vaccination regimen did not appear to be strongly immunogenic in foals. Alternative dosing regimens or routes of administration need further investigation and may prove to be immunogenic and protective.
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Affiliation(s)
- Joana N. Rocha
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, 77843–4475, United States of America
| | - Noah D. Cohen
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, 77843–4475, United States of America
- * E-mail: (NDC); (SDP)
| | - Angela I. Bordin
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, 77843–4475, United States of America
| | - Courtney N. Brake
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, 77843–4475, United States of America
| | - Steeve Giguère
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, 30602–7385, United States of America
| | - Michelle C. Coleman
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, 77843–4475, United States of America
| | - Robert C. Alaniz
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, Texas, 77843, United States of America
| | - Sara D. Lawhon
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, 77843–4467, United States of America
| | - Waithaka Mwangi
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, 77843–4467, United States of America
| | - Suresh D. Pillai
- National Center for Electron Beam Research–IAEA Collaborative Centre for Electron Beam Technology, Texas A&M University, College Station, Texas, 77843, United States of America
- * E-mail: (NDC); (SDP)
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10
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Cohen ND, Giguère S, Burton AJ, Rocha JN, Berghaus LJ, Brake CN, Bordin AI, Coleman MC. Use of Liposomal Gentamicin for Treatment of 5 Foals with Experimentally Induced Rhodococcus equi Pneumonia. J Vet Intern Med 2015; 30:322-5. [PMID: 26692327 PMCID: PMC4913631 DOI: 10.1111/jvim.13810] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 10/26/2015] [Accepted: 11/16/2015] [Indexed: 02/02/2023] Open
Abstract
Background 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. Hypothesis Liposomal gentamicin is safe and effective for treating foals with R. equi pneumonia. Animals 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 and Clinical Importance 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.
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Affiliation(s)
- N D Cohen
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX
| | - S Giguère
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - A J Burton
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - J N Rocha
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX
| | - L J Berghaus
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - C N Brake
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX
| | - A I Bordin
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX
| | - M C Coleman
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX
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Burton AJ, Giguère S, Berghaus LJ, Hondalus MK, Arnold RD. 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. [PMID: 25666452 DOI: 10.1016/j.vetmic.2015.01.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 01/16/2015] [Accepted: 01/19/2015] [Indexed: 11/24/2022]
Abstract
Rhodococcus equi, a facultative intracellular pathogen and an important cause of pneumonia in foals, is highly susceptible to killing by gentamicin in vitro. However, gentamicin is not effective in vivo, due to its poor cellular penetration. Encapsulation of drugs in liposomes enhances cellular uptake. The objectives of this study were to compare liposomal gentamicin and free gentamicin with respect to their uptake by equine macrophages and intracellular colocalization with R. equi and to compare the efficacies of liposomal gentamicin, free gentamicin and clarithromycin with rifampin for the reduction of R. equi CFU in a mouse model of infection. After ex vivo exposure, a significantly higher mean (±SD) percentage of equine alveolar macrophages contained liposomal gentamicin (91.9±7.6%) as opposed to free gentamicin (16.8±12.5%). Intracellular colocalization of drug and R. equi, as assessed by confocal microscopy, occurred in a significantly higher proportion of cells exposed to liposomal gentamicin (81.2±17.8%) compared to those exposed to free gentamicin (10.4±8.7%). The number of R. equi CFU in the spleen was significantly lower in mice treated with liposomal gentamicin compared to that of mice treated with free gentamicin or to untreated control mice. Treatment with liposomal gentamicin also resulted in a significantly greater reduction in the number of R. equi CFU in the liver compared to treatment with clarithromycin in combination with rifampin. These results support further investigation of liposomal gentamicin as a new treatment for infections caused by R. equi.
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Affiliation(s)
- Alexandra J Burton
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Steeve Giguère
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, United States.
| | - Londa J Berghaus
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Mary K Hondalus
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Robert D Arnold
- Department of Drug Discovery & Development, Harrison School of Pharmacy, Auburn University, Auburn, AL, United States
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