RESUMEN
The intraspecific variability of E. ictaluri isolates from different origins was investigated. Isolates were recovered from farm-raised catfish (Ictalurus punctatus) in Mississippi, USA, tilapia (Oreochromis niloticus) cultured in the Western Hemisphere and zebrafish (Danio rerio) propagated in Florida, USA. These isolates were phenotypically homologous and antimicrobial profiles were largely similar. Genetically, isolates possessed differences that could be exploited by repetitive-sequence-mediated PCR and gyrB sequence, which identified three distinct E. ictaluri genotypes: one associated with catfish, one from tilapia and a third from zebrafish. Plasmid profiles were also group specific and correlated with rep-PCR and gyrB sequences. The catfish isolates possessed profiles typical of those described for E. ictaluri isolates; however, plasmids from the zebrafish and tilapia isolates differed in both composition and arrangement. Furthermore, some zebrafish and tilapia isolates were PCR negative for several E. ictaluri virulence factors. Isolates were serologically heterogenous, as serum from a channel catfish exposed to a catfish isolate had reduced antibody activity to tilapia and zebrafish isolates. This work identifies three genetically distinct strains of E. ictaluri from different origins using rep-PCR, 16S, gyrB and plasmid sequencing, in addition to antimicrobial and serological profiling.
Asunto(s)
Cíclidos , Edwardsiella ictaluri/clasificación , Edwardsiella ictaluri/genética , Infecciones por Enterobacteriaceae/veterinaria , Enfermedades de los Peces/microbiología , Ictaluridae , Pez Cebra , Animales , Proteínas Bacterianas/genética , Girasa de ADN/genética , Infecciones por Enterobacteriaceae/microbiología , Florida , Genotipo , Geografía , Mississippi , Filogenia , Plásmidos/genética , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Alineación de Secuencia/veterinaria , Factores de Virulencia/genéticaRESUMEN
Plasma disposition of florfenicol in channel catfish was investigated after an oral multidose (10 mg/kg for 10 days) administration in freshwater at water temperatures ranging from 24.7 to 25.9 °C. Florfenicol concentrations in plasma were analyzed by means of liquid chromatography with MS/MS detection. After the administration of florfenicol, the mean terminal half-life (t(1/2)), maximum concentration at steady-state (Css (max)), time of Css (max) (T(max)), minimal concentration at steady-state (Css (min)), and Vc /F were 9.0 h, 9.72 µg/mL, 8 h, 2.53 µg/mL, and 0.653 L/kg, respectively. These results suggest that florfenicol administered orally at 10 mg/kg body weight for 10 days could be expected to control catfish bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of <2.5 µg/mL.
Asunto(s)
Antibacterianos/farmacocinética , Ictaluridae/metabolismo , Tianfenicol/análogos & derivados , Administración Oral , Animales , Antibacterianos/administración & dosificación , Antibacterianos/sangre , Cromatografía Líquida de Alta Presión/métodos , Cromatografía Líquida de Alta Presión/veterinaria , Ictaluridae/sangre , Espectrometría de Masas en Tándem/métodos , Espectrometría de Masas en Tándem/veterinaria , Tianfenicol/administración & dosificación , Tianfenicol/sangre , Tianfenicol/farmacocinéticaRESUMEN
Francisella noatunensis subsp. orientalis (Fno) (syn. F. asiatica) is an emergent Gram-negative facultative intracellular bacterium. Although it is considered one of the most pathogenic bacteria in fish, there are no commercially available treatments or vaccines. The objective of this project was to determine the most efficacious concentration of florfenicol (FFC) [10, 15 or 20 mg FFC kg(-1) body weight (bw) per days for 10 days] administered in feed to control experimentally induced infections of Fno in Nile tilapia, Oreochromis niloticus (L.), reared in a recirculating aquaculture system. The cumulative mortality of fish that received 0, 10, 15 or 20 mg FFC kg(-1) bw per day was 60, 37, 14 and 16%, respectively. Francisella noatunensis subsp. orientalis genome equivalents were detected in water from all challenged groups with slight reduction in the concentration in the florfenicol-treated groups 4 days after treatment. The mean LOG of CFU Fno mg(-1) spleen was 3-5 and was present in all challenged groups at necropsy 11 days after treatment (21 days after challenge). Results show that florfenicol administered at doses of 15 and 20 mg FFC kg(-1) bw per days for 10 days significantly reduced mortality associated with francisellosis in Nile tilapia.
Asunto(s)
Antibacterianos/uso terapéutico , Cíclidos , Enfermedades de los Peces/tratamiento farmacológico , Francisella/clasificación , Infecciones por Bacterias Gramnegativas/veterinaria , Tianfenicol/análogos & derivados , Alimentación Animal , Animales , Esquema de Medicación , Ingestión de Alimentos , Enfermedades de los Peces/microbiología , Enfermedades de los Peces/mortalidad , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Infecciones por Bacterias Gramnegativas/microbiología , Tianfenicol/uso terapéuticoRESUMEN
Plasma distribution and elimination of florfenicol in channel catfish were investigated after a single dose (10 mg/kg) of intravenous (i.v.) or oral administration in freshwater at a mean water temperature of 25.4 °C. Florfenicol concentrations in plasma were analyzed by means of liquid chromatography with MS/MS detection. After i.v. florfenicol injection, the terminal half-life (t(1/2)), volume of distribution at steady state (V(ss)), and central volume of distribution (V(c)) were 8.25 h, 0.9 and 0.381 L/kg, respectively. After oral administration of florfenicol, the terminal t(1/2), C(max), T(max), and oral bioavailability (F) were 9.11 h, 7.6 µg/mL, 9.2 h, and 1.09, respectively. There was a lag absorption time of 1.67 h in oral dosing. Results from these studies support that 10 mg florfenicol/kg body weight in channel catfish is an efficacious dosage following oral administration.