Chemoprophylactic effects of azithromycin against Rhodococcus equi-induced pneumonia among foals at equine breeding farms with endemic infections.
Abstract: To determine the effect of azithromycin chemoprophylaxis on the cumulative incidence of pneumonia caused by Rhodococcus equi, age at onset of pneumonia, and minimum inhibitory concentration (MIC) of azithromycin for R equi isolates cultured from fecal and clinical samples. Methods: Controlled, randomized clinical trial. Methods: 338 foals born and raised at 10 equine breeding farms; each farm had a history of endemic R equi infections. Methods: Group 1 foals were control foals, and group 2 foals were treated with azithromycin (10 mg/kg [4.5 mg/lb], PO, q 48 h) during the first 2 weeks after birth. Foals were monitored for development of pneumonia attributable to R equi infection and for adverse effects of azithromycin. Isolates of R equi were tested for susceptibility to azithromycin. Results: The proportion of R equi-affected foals was significantly higher for control foals (20.8%) than for azithromycin-treated foals (5.3%). Adverse effects of azithromycin treatment were not detected, and there were no significant differences between groups for the MICs of azithromycin for R equi isolates cultured from fecal or clinical samples. Conclusions: Azithromycin chemoprophylaxis effectively reduced the cumulative incidence of pneumonia attributable to R equi among foals at breeding farms with endemic R equi infections. There was no evidence of resistance to azithromycin. Nonetheless, caution must be used because it is possible that resistance could develop with widespread use of azithromycin as a preventative treatment. Further investigation is needed before azithromycin chemoprophylaxis can be recommended for control of R equi infections.
Publication Date: 2008-04-03 PubMed ID: 18380623DOI: 10.2460/javma.232.7.1035Google Scholar: Lookup
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- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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The research investigates the potential benefits of using azithromycin to prevent pneumonia caused by Rhodococcus equi infection in young horses on farms with a history of this infection.
Research Design and Methods
- The study was a controlled, randomized clinical trial performed on 338 foals born and raised at ten different equine breeding farms with a history of endemic Rhodococcus equi infections.
- The young horses were split into two groups; the control group (Group 1) which did not receive any treatment and the second group (Group 2) which was treated with azithromycin. The dosage was 10 mg/kg administered orally every 48 hours during the first two weeks after birth.
- The development of pneumonia in the foals due to the R equi infection and any adverse effects from the azithromycin treatment were closely monitored. The R equi isolates cultured from the foals’ fecal and clinical samples were tested for susceptibility to azithromycin.
Research Findings
- The results indicated a significantly lower percentage of R equi infections among the azithromycin-treated foals (5.3%) compared to the control group (20.8%).
- No adverse effects from the azithromycin treatment were identified.
- There were no significant differences between the Minimum Inhibitory Concentrations (MICs – a measure of the effectiveness of an antimicrobial agent) of azithromycin for the R equi isolates cultured from either fecal or clinical samples among the two different groups of foals.
Conclusions and Recommendations
- The researchers concluded that using azithromycin as a preventative measure can effectively reduce the cumulative incidence of pneumonia caused by R equi infections among young horses at breeding farms with a history of these infections.
- There was no evidence found that suggested any resistance to the azithromycin drug.
- However, the study urges caution as resistance could develop with widespread use of azithromycin as a preventative measure. Consequently, further investigation is needed before it can be recommended for controlling R equi infections.
Cite This Article
APA
Chaffin MK, Cohen ND, Martens RJ.
(2008).
Chemoprophylactic effects of azithromycin against Rhodococcus equi-induced pneumonia among foals at equine breeding farms with endemic infections.
J Am Vet Med Assoc, 232(7), 1035-1047.
https://doi.org/10.2460/javma.232.7.1035 Publication
Researcher Affiliations
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4475, USA.
MeSH Terms
- Actinomycetales Infections / epidemiology
- Actinomycetales Infections / prevention & control
- Actinomycetales Infections / veterinary
- Animals
- Animals, Newborn
- Anti-Bacterial Agents / therapeutic use
- Antibiotic Prophylaxis / veterinary
- Azithromycin / therapeutic use
- Dose-Response Relationship, Drug
- Drug Resistance, Bacterial
- Female
- Horse Diseases / epidemiology
- Horse Diseases / prevention & control
- Horses
- Male
- Microbial Sensitivity Tests / veterinary
- Pneumonia, Bacterial / epidemiology
- Pneumonia, Bacterial / prevention & control
- Pneumonia, Bacterial / veterinary
- Rhodococcus equi / drug effects
- Rhodococcus equi / pathogenicity
- Treatment Outcome
Citations
This article has been cited 15 times.- Kahn SK, Cywes-Bentley C, Blodgett GP, Canaday NM, Turner-Garcia CE, Flores-Ahlschwede P, Metcalfe LL, Nevill M, Vinacur M, Sutter PJ, Meyer SC, Bordin AI, Pier GB, Cohen ND. Randomized, controlled trial comparing Rhodococcus equi and poly-N-acetyl glucosamine hyperimmune plasma to prevent R equi pneumonia in foals.. J Vet Intern Med 2021 Nov;35(6):2912-2919.
- Kahn SK, Cywes-Bentley C, Blodgett GP, Canaday NM, Turner-Garcia CE, Vinacur M, Cortez-Ramirez SC, Sutter PJ, Meyer SC, Bordin AI, Vlock DR, Pier GB, Cohen ND. Antibody activities in hyperimmune plasma against the Rhodococcus equi virulence -associated protein A or poly-N-acetyl glucosamine are associated with protection of foals against rhodococcal pneumonia.. PLoS One 2021;16(8):e0250133.
- Cohen ND, Kahn SK, Cywes-Bentley C, Ramirez-Cortez S, Schuckert AE, Vinacur M, Bordin AI, Pier GB. Serum Antibody Activity against Poly-N-Acetyl Glucosamine (PNAG), but Not PNAG Vaccination Status, Is Associated with Protecting Newborn Foals against Intrabronchial Infection with Rhodococcus equi.. Microbiol Spectr 2021 Sep 3;9(1):e0063821.
- Álvarez-Narváez S, Huber L, Giguère S, Hart KA, Berghaus RD, Sanchez S, Cohen ND. Epidemiology and Molecular Basis of Multidrug Resistance in Rhodococcus equi.. Microbiol Mol Biol Rev 2021 May 19;85(2).
- Bordin AI, Cohen ND, Giguère S, Bray JM, Berghaus LJ, Scott B, Johnson R, Hook M. Host-directed therapy in foals can enhance functional innate immunity and reduce severity of Rhodococcus equi pneumonia.. Sci Rep 2021 Jan 28;11(1):2483.
- Rakowska A, Cywinska A, Witkowski L. Current Trends in Understanding and Managing Equine Rhodococcosis.. Animals (Basel) 2020 Oct 18;10(10).
- Álvarez-Narváez S, Berghaus LJ, Morris ERA, Willingham-Lane JM, Slovis NM, Giguere S, Cohen ND. A Common Practice of Widespread Antimicrobial Use in Horse Production Promotes Multi-Drug Resistance.. Sci Rep 2020 Jan 22;10(1):911.
- Álvarez-Narváez S, Giguère S, Anastasi E, Hearn J, Scortti M, Vázquez-Boland JA. Clonal Confinement of a Highly Mobile Resistance Element Driven by Combination Therapy in Rhodococcus equi.. mBio 2019 Oct 15;10(5).
- Rocha JN, Dangott LJ, Mwangi W, Alaniz RC, Bordin AI, Cywes-Bentley C, Lawhon SD, Pillai SD, Bray JM, Pier GB, Cohen ND. PNAG-specific equine IgG(1) mediates significantly greater opsonization and killing of Prescottella equi (formerly Rhodococcus equi) than does IgG(4/7).. Vaccine 2019 Feb 21;37(9):1142-1150.
- 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(2):e0148111.
- Madrigal RG, Shaw SD, Witkowski LA, Sisson BE, Blodgett GP, Chaffin MK, Cohen ND. Use of Serial Quantitative PCR of the vapA Gene of Rhodococcus equi in Feces for Early Detection of R. equi Pneumonia in Foals.. J Vet Intern Med 2016 Mar-Apr;30(2):664-70.
- Whitfield-Cargile CM, Cohen ND, Suchodolski J, Chaffin MK, McQueen CM, Arnold CE, Dowd SE, Blodgett GP. Composition and Diversity of the Fecal Microbiome and Inferred Fecal Metagenome Does Not Predict Subsequent Pneumonia Caused by Rhodococcus equi in Foals.. PLoS One 2015;10(8):e0136586.
- Bordin AI, Pillai SD, Brake C, Bagley KB, Bourquin JR, Coleman M, Oliveira FN, Mwangi W, McMurray DN, Love CC, Felippe MJ, Cohen ND. Immunogenicity of an electron beam inactivated Rhodococcus equi vaccine in neonatal foals.. PLoS One 2014;9(8):e105367.
- Bordin AI, Suchodolski JS, Markel ME, Weaver KB, Steiner JM, Dowd SE, Pillai S, Cohen ND. Effects of administration of live or inactivated virulent Rhodococccus equi and age on the fecal microbiome of neonatal foals.. PLoS One 2013;8(6):e66640.
- Kachroo P, Ivanov I, Seabury AG, Liu M, Chowdhary BP, Cohen ND. Age-related changes following in vitro stimulation with Rhodococcus equi of peripheral blood leukocytes from neonatal foals.. PLoS One 2013;8(5):e62879.
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