Jarau Maureen, MacInnes Janet I, Lumsden John S
Fish Pathology Laboratory, University of Guelph, Guelph, Ontario, Canada.
Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada.
J Fish Dis. 2019 Mar;42(3):325-334. doi: 10.1111/jfd.12944. Epub 2019 Jan 11.
Flavobacterium psychrophilum is responsible for significant economic losses in rainbow trout aquaculture. Antimicrobial treatment remains the primary means of control; however, there are limited choices available for use. The objectives of the study were therefore to determine the minimum inhibitory concentrations for erythromycin and florfenicol in selected F. psychrophilum isolates and to evaluate their clinical treatment efficacy in experimentally infected rainbow trout. All isolates tested had moderate susceptibility to florfenicol and erythromycin except one isolate, which had low susceptibility to erythromycin. Two isolates (one with moderate and one with low susceptibility to erythromycin) were used in an experimental infection trial. Rainbow trout juveniles were injected intraperitoneally with 10 cfu/fish and after mortality had begun, fish were given erythromycin- and florfenicol-medicated feed at a rate of 75 mg kg day and 10 mg kg day fish body weight, respectively, for 10 consecutive days. The splenic F. psychrophilum load was determined using an rpoC quantitative PCR throughout the 30-day trial. Relative to antibiotic-free controls, erythromycin treatment significantly (p < 0.05) reduced mortality of rainbow trout juveniles infected with FPG101, even when treatment was initiated after clinical signs developed.
嗜冷黄杆菌会给虹鳟鱼养殖造成重大经济损失。抗菌治疗仍是主要的控制手段；然而，可用的选择有限。因此，本研究的目的是确定所选嗜冷黄杆菌分离株对红霉素和氟苯尼考的最低抑菌浓度，并评估它们在实验感染的虹鳟鱼中的临床治疗效果。除了一株对红霉素敏感性较低的分离株外，所有测试的分离株对氟苯尼考和红霉素均具有中等敏感性。在一项实验感染试验中使用了两株分离株（一株对红霉素敏感性中等，一株对红霉素敏感性较低）。对虹鳟幼鱼腹腔注射10 cfu/鱼，在开始出现死亡后，分别以75 mg/kg鱼体重·天和10 mg/kg鱼体重·天的剂量连续10天给鱼投喂含红霉素和氟苯尼考的药饵。在整个30天的试验中，使用rpoC定量PCR测定脾脏嗜冷黄杆菌载量。相对于无抗生素对照组，红霉素治疗显著（p<0.05）降低了感染FPG101的虹鳟幼鱼死亡率，即使在出现临床症状后开始治疗也是如此。
