The efficacy of amoxicillin sodium against streptococcosis in cultured olive flounder Paralichthys olivaceus and its pharmacokinetics

Abstract

The efficacy of amoxicillin sodium for controlling field and experimental Streptococcus iniae and S. parauberis infections in olive flounder (Paralichthys olivaceus) was evaluated after a single intramuscular administration. Furthermore, the minimal inhibitory concentrations (MIC) against 21 Streptococcus strains were determined. In addition, the pharmacokinetics and residue depletion in olive flounder were investigated. Single intramuscular doses of amoxicillin sodium at 20, 40, 80, and 160 mg/kg b.w. fish significantly reduced cumulative mortality rates to 18.8-31.3% (P < 0.05) for S. iniae and to 5.0-15.0% (P < 0.01) for S. parauberis, whereas the S. iniae- and S. parauberis-infected positive control groups showed cumulative mortality rates of 68.8% and 60.0%, respectively. In a S. parauberis outbreak, amoxicillin sodium reduced the cumulative mortality rate to 7.5% and 4.8% at 20 and 40 mg/kg b.w. fish, respectively, whereas that of the untreated control group was 35.2%. Peak plasma concentrations (C ) following a single intramuscular dose of 40 and 80 mg/kg b.w. fish were 62.64 (T , 1.59 h) and 87.61 (T , 3.02 h) μg/mL, respectively, with large AUC /MIC and C /MIC ratios, and sufficient T > MIC (time for maintaining plasma drug concentration greater than MICs) for S. iniae and S. parauberis. The estimated withdrawal period of amoxicillin sodium from muscle of olive flounder was about 8 days at 40 mg/kg b.w. fish (at 22 ± 1 °C). These results demonstrated a single intramuscular administration of amoxicillin sodium to be effective against streptococcosis in olive flounder.

Estimation of pharmacological properties of ceftiofur, an injectable cephalosporin antibiotic, for treatment of streptococcosis in cultured olive flounderParalichthys olivaceus

“…Parenteral administration of drugs in culture fish is mostly limited to specific agents like vaccines, reproduction controllers or anaesthetics due to technical difficulty and high labour costs (Black, 2000). In recent years, however, the application of some injectable drugs has been found feasible when they were administered intramuscularly in Korean culture farms, particularly for olive flounder (Lee & Park, 2015; Lim et al., 2017; Seo et al., 2015). This fish species is generally calm and can easily be handled without excess stress during injections.…”

“…For instance, Lim et al. (2017) found out that i.m. amoxicillin could effectively reduce the mortality caused by S. iniae and S. parauberis infections in olive flounder.…”

“…Surrogate markers of antibacterial efficacy, including the plasma concentration ( C max )/MIC 50 , area under the concentration–time curve (AUC 0‐ t or AUC 0‐inf )/ MIC 50 and the duration of time ( T > MIC 50 ) over MIC 50 , were determined using in vitro MIC 50 data and in vivo PK parameters (Lees et al., 2015; Lim et al., 2017; Park et al., 2016).…”

“…Diseased fish exhibit dark body discoloration, exophthalmos, fin haemorrhage, systemic septicaemia and eventual death (Harvie et al., 2013). Infected fish with highly pathogenic strains usually show mortality rates higher than 50%, with death generally occurring between 3 and 7 days after infection (Lim et al., 2017). Chronic infections, in which low daily mortality is observed over months, have also been reported (Lee et al., 2007).…”

Antibacterial Activities of Prenylated Isoflavones from Maclura tricuspidata against Fish Pathogenic Streptococcus: Their Structure-Activity Relationships and Extraction Optimization

“…Antibacterial activity was evaluated with a broth dilution method (approved guideline: M49-A) as described by the Clinical and Laboratory Standards Institute [25] with slight modifications [26,27]. Briefly, bacterial colonies taken directly from brain heart infusion agar (BHIA) plates were incubated into BHIB and cultured at 25 • C for 24 h. From this culture, a suspension equivalent to 0.5 McFarland standard in BHIB was prepared.…”