title: Use of Liposomal Gentamicin for Treatment of 5 Foals with Experimentally Induced Rhodococcus equi Pneumonia.
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.
  
  
  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.
authors.affiliation: Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
authors.forename: N D
authors.initials: ND
authors.lastname: Cohen
authors.affiliation: Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA.
authors.forename: S
authors.initials: S
authors.lastname: Giguère
authors.affiliation: Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Burton
authors.affiliation: Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
authors.forename: J N
authors.initials: JN
authors.lastname: Rocha
authors.affiliation: Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Berghaus
authors.affiliation: Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
authors.forename: C N
authors.initials: CN
authors.lastname: Brake
authors.affiliation: Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
authors.forename: A I
authors.initials: AI
authors.lastname: Bordin
authors.affiliation: Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX.
authors.forename: M C
authors.initials: MC
authors.lastname: Coleman
mesh_terms: D000193:Actinomycetales Infections / Q000382:microbiology / Q000662:veterinary*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use; D017291:Clarithromycin / Q000008:administration & dosage / Q000627:therapeutic use; D005839:Gentamicins / Q000008:administration & dosage / Q000627:therapeutic use*; D006734:Horse Diseases / Q000188:drug therapy / Q000382:microbiology*; D006736:Horses; D008081:Liposomes; D016929:Rhodococcus equi; D012293:Rifampin / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D008081:Liposomes; D017291:Clarithromycin; D012293:Rifampin
keywords: Adverse effects; Antibiotic choices; Macrolides; Nephrotoxicity