INITIAL DISEASE REPORT OF STREPTOCOCCUS-INIAE INFECTION IN HYBRID STRIPED (SUNSHINE) BASS AND SUCCESSFUL THERAPEUTIC INTERVENTION WITH THE FLUOROQUINOLONE ANTIBACTERIAL ENROFLOXACIN
Da. Stoffregen et al., INITIAL DISEASE REPORT OF STREPTOCOCCUS-INIAE INFECTION IN HYBRID STRIPED (SUNSHINE) BASS AND SUCCESSFUL THERAPEUTIC INTERVENTION WITH THE FLUOROQUINOLONE ANTIBACTERIAL ENROFLOXACIN, Journal of the World Aquaculture Society, 27(4), 1996, pp. 420-434
Streptococcal infection (Streptococcus iniae) was diagnosed sequential
ly in two tanks of hybrid striped bass Morone saxatilis male x M. chry
sops female (Sunshine bass) grown in a commercial freshwater recircula
tion facility in western Massachusetts. The pathogen was isolated in t
he laboratory, biochemically and morphologically characterized, and an
tibacterial sensitivities determined. Streptococcus iniae-induced lesi
ons in the Sunshine bass were characterized at the gross and histopath
ological levels. Initial treatment with oxytetracycline was unsuccessf
ul. Based on sensitivity results, enrofloxacin-medicated feed was dose
d at 10 mg/kg body weight for 10 d, while a subsequent trial was condu
cted at 5 mg/kg body weight for 10 d. Mortality of fish subsided promp
tly following initiation of enrofloxacin therapy, yielding a final mor
tality in the initial tank of 10.83% (control tank 55.5%) and in the s
econd tank of 16.97% (control tank 39.8%). Tissue enrofloxacin residue
s, detected via a microbiologic bioassay, revealed greater quantities
and longer duration of residues in various tissues from the 5-mg as co
mpared to the 10-mg trial, potentially the result of adverse feed pala
tability. Enrofloxacin appears to have excellent potential as an antib
acterial agent for treating susceptible bacterial diseases of Sunshine
bass.