title: In vivo bactericidal effect of Melaleuca alternifolia essential oil against Aeromonas hydrophila: Silver catfish (Rhamdia quelen) as an experimental model.
abstract: Aeromonas hydrophila is one of the main causative agent of high mortality and significative economic losses in aquaculture and has become increasingly resistant to conventional antibiotics. One feasible alternative to control and treat it is the use of essential oils. This study aimed to evaluate A. hydrophila susceptibility to tea tree oil (TTO-Melaleuca alternifolia) in vivo, and the effect of this treatment. In vivo tests were performed using silver catfish (Rhamdia quelen) as the experimental model. Silver catfish were treated with TTO at 25 and 50 μL/L for seven days before infection. After seven days, the fish were inoculated with A. hydrophila via intramuscularly. Treatment with TTO at 50 μL/L was able to extend longevity of infected fish, and showed 88% of therapeutic success, even though it did not show curative efficacy. TTO treatment was not toxic under these tested concentrations, since biomarkers of hepatic and renal functions were not affected, and the concentration of 50 μL/L was able to prevent increased levels of aspartate aminotransferase. There was no significative differences regarding hematological parameters (p < 0.05). Treatment with TTO 50 μL/L was able to reduce histopathological alterations usually caused by this type of bacteria in the gills, but it was unable to reduce hepatic histopathological alterations. Our results showed, for the first time, that TTO has high activity against A. hydrophila and proved to be a natural alternative to prevent and control this pathogen.
authors.affiliation: Department of Physiology and Pharmacology, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil. Electronic address: carinedefs@yahoo.com.br.
authors.forename: Carine
authors.initials: C
authors.lastname: F Souza
authors.affiliation: Department of Microbiology and Parasitology, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Matheus D
authors.initials: MD
authors.lastname: Baldissera
authors.affiliation: Laboratory of Nanotechnology, Centro Universitário Franciscano, Santa Maria, RS, Brazil; Laboratory of Microbiology, Centro Universitário Franciscano, Santa Maria, RS, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: A Vaucher
authors.affiliation: Laboratory of Nanotechnology, Centro Universitário Franciscano, Santa Maria, RS, Brazil; Laboratory of Microbiology, Centro Universitário Franciscano, Santa Maria, RS, Brazil.
authors.forename: Leonardo Q S
authors.initials: LQ
authors.lastname: Lopes
authors.affiliation: Laboratory of Microbiology, Centro Universitário Franciscano, Santa Maria, RS, Brazil.
authors.forename: Bruno S
authors.initials: BS
authors.lastname: Vizzotto
authors.affiliation: Laboratory of Nanotechnology, Centro Universitário Franciscano, Santa Maria, RS, Brazil.
authors.forename: Renata P
authors.initials: RP
authors.lastname: Raffin
authors.affiliation: Laboratory of Nanotechnology, Centro Universitário Franciscano, Santa Maria, RS, Brazil; Laboratory of Microbiology, Centro Universitário Franciscano, Santa Maria, RS, Brazil.
authors.forename: Roberto C V
authors.initials: RC
authors.lastname: Santos
authors.affiliation: Laboratory of Experimental Morphophysiology, Department of Morphology, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: L da Veiga
authors.affiliation: Laboratory of Experimental Morphophysiology, Department of Morphology, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Maria Izabel
authors.initials: MI
authors.lastname: U M da Rocha
authors.affiliation: Department of Animal Science, Universidade do Estado de Santa Catarina (UDESC), Chapecó, SC, Brazil.
authors.forename: Lenita M
authors.initials: LM
authors.lastname: Stefani
authors.affiliation: Department of Physiology and Pharmacology, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Baldisserotto
mesh_terms: D016980:Aeromonas hydrophila / Q000187:drug effects*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000302:isolation & purification / Q000494:pharmacology*; D002397:Catfishes / Q000382:microbiology; D005393:Fish Diseases / Q000188:drug therapy / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control; D005880:Gills / Q000473:pathology; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D006651:Histocytochemistry; D007273:Injections, Intramuscular; D007677:Kidney Function Tests; D008099:Liver / Q000473:pathology / Q000503:physiopathology; D008111:Liver Function Tests; D031650:Melaleuca / Q000737:chemistry*; D008962:Models, Theoretical; D009822:Oils, Volatile / Q000008:administration & dosage* / Q000009:adverse effects / Q000302:isolation & purification / Q000494:pharmacology*; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D009822:Oils, Volatile
keywords: Aeromonas hydrophila; Antimicrobial action; Fish; TTO