Florfenicol e biciclomicina: eficÃcia in vitro contra bactÃrias patogÃnicas de peixes de Ãgua doce. / In vitro efficacy of florfenicol e bicyclomycin to pathogenic bacteria from freshwater fish.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The Streptococcus agalactiae and the motile aeromonads are major pathogens for several tropical fish species, causing encephalitis and septicemia outbreaks, respectively, with high mortality in intensive culture systems. The use of antibiotic is the main control measure. The objective of this work was to determine the minimum inhibitory concentration (MIC) of florfenicol (FLO) and bicyclomycin (BCM) for motile aeromonads isolated of diseased fish and pond water, and S. agalactiae isolated from fish. One hundred eighteen strains of motile aeromonads and 27 strains of S. agalactiae were selected from different Brazilian states. The methodology used for determination of the MIC was the microdilution in broth, in accordance with âMethod for Broth Dilution Susceptibility Testing of Bacteria Isolated from Aquatic Animalsâ, established for the Clinical and Laboratory Standards Institute (CLSI, 2006). All test were carried out with an incubation temperature of 28ÂC and serial two-fold dilution of florfenicol (0,06 â 64 mg mL-1) and bicyclomycin (0,195 â 200mg mL-1) were used. All strains were classified as susceptible or resistant according to the profile of data distribution (continuous or modal). To S. agalactiae, the MIC values to FLO ranged from 1 mg mL-1 to 16 mg mL-1 and to BCM from 3.12 mg mL-1 to 12.5 mg mL-1. In both cases it was observed the distribution of values in one cluster and all strains analyzed were classified as susceptible to FLO and BCM. To motile aeromonads, the MIC values to FLO ranged from 0.5 mg mL-1 to 16 mg mL-1 and to BCM from 0.78 mg mL-1 to 100 mg mL-1. To the both antibiotics the MIC values presented a continuous distribution. In the motile aeromonads isolated from pond water it was observed a bimodal profile for MIC values of BCM, characterizing a susceptible population (MIC <6.25 mg mL-1) and other resistant (MIC >50 mg mL-1) to the antibiotic. Both antibiotics presented a high effectivity in vitro against motile aeromonads and S. agalactiae strains.

ASSUNTO(S)

minimum inhibitory concentration. medicina veterinaria preventiva motile aeromonads bicyclomycin florfenicol biciclomicina concentraÃÃo inibitÃria mÃnima florfenicol fish streptococcus agalactiae. streptococcus agalactiae aeromonas mÃveis

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