The application of injectable antibiotics has not been actively adopted in aquaculture despite some clear advantages over the oral administration under certain circumstances. This study aimed to assess the applicability of intramuscularly (i.m.) injectable ceftiofur sodium (CS), a cephalosporin, to treat streptococcal infection in olive flounder (Paralichthys olivaceus). The efficacy of CS was estimated in vitro with 48 different clinical isolates of Streptococcus parauberis: it was found that growth of 32 isolates (66.7%) was inhibited by 0.25 μg/ml and 47 isolates (97.9%) by 8 μg/ml CS. The in vivo laboratory efficacy showed that 20–40 mg/kg single CS (i.m.) injection completely prevented olive flounder from death while streptococcal infection led to 100% mortality without CS. In a field study, CS was administered at 10 or 20 mg/kg i.m. to naturally infected olive flounder in culture farms, and significant mortality prevention was observed by either dose. Plasma and muscle concentrations of CS were monitored in the laboratory following single CS injections at 10 and 20 mg/kg (i.m.) to estimate pharmacokinetic parameters. Peak plasma concentrations (C_max) were 7.61 and 13.34 µg/ml, respectively, after the two doses leading to large C_max/MIC₅₀ and T > MIC₅₀ (time period stayed at above MIC₅₀) values against S. parauberis. Analyses of residue depletion from the muscle demonstrated legitimate withdrawal times of 4.15 days after 10 mg/kg and 4.32 days after 20 mg/kg. These results collectively indicate that a single i.m. injection of CS above 10 mg/kg is acceptably efficacious with reasonable withdrawal periods in streptococcal infection of olive flounder.

中文翻译：

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头孢噻呋，头孢类抗生素注射剂，用于治疗养殖比目鱼的链球菌病的药理学特性评估

尽管在某些情况下与口服给药相比有明显的优势，但在水产养殖中并未积极采用可注射抗生素的应用。这项研究旨在评估肌注（im）头孢噻呋钠（CS），一种头孢菌素，在治疗比目鱼（Stralichthys olivaceus）中链球菌感染的适用性。CS的功效是在体外用48株副乳房链球菌临床分离株评估的：发现0.25μg/ ml抑制了32个菌株（66.7％）的生长，而8μg/ ml CS抑制了47个菌株（97.9％）的生长。体内实验室功效表明，单次CS（im）注射20–40 mg / kg完全可以防止橄榄比目鱼死亡，而链球菌感染导致没有CS时死亡率为100％。在一项田间研究中，在养殖场中对自然感染的比目鱼以10或20 mg / kg im的剂量施用CS，无论用哪种剂量均可观察到明显的死亡率预防作用。在实验室中以10和20 mg / kg（im）的单次CS注射后，监测CS的血浆和肌肉浓度，以估计药代动力学参数。两次剂量导致_最大C _max后，血浆峰值浓度（C _max）分别为7.61和13.34 µg / ml。/ MIC ₅₀和T  > MIC ₅₀（时间段保持在MIC ₅₀以上）相对于伞形葡萄球菌的值。从肌肉中清除残留物的分析显示，合法停药时间分别为10 mg / kg后4.15天和20 mg / kg后4.32天。这些结果共同表明，在比目鱼链球菌感染中，单次im注射CS剂量大于10 mg / kg并具有合理的停药期是可以接受的。